Monitoring the switch: The warburg effect and targeted proteomic analysis of cancer metabolism - Murphy, J.P.; Côté, P.D.; Pinto, D.M. (Current Proteomics, 2012)
Cancer cells dramatically alter their metabolism in order to increase the production rate of intermediates required for nucleic and fatty acid biosynthesis in rapidly proliferating cells. While not well understood, dysregulation of oncogenes and tumour suppressors appears to result in the altered expression of specific isoforms of glycolysis proteins. A full understanding of glycolytic alterations in cancer through a systems biology approach requires tools to observe changes in the set of proteins that make up the glycolytic proteome. We propose that a targeted proteomics approach employing multiple reaction monitoring (MRM) is an excellent strategy to quantitatively monitor sets of proteins, such as those making up the glycolytic proteome. MRM is particularly well suited to proteins of glycolysis as they are of moderate to high abundance. Such systems-based efforts provide a means to understand the mechanisms for an altered glycolytic proteome in cancer, perhaps leading to novel drug targets and metabolic signatures for use in cancer prognosis. ©2012 Bentham Science Publishers.
Keywords: glucose; glucose 6 phosphate dehydrogenase; hexokinase; hexokinase 2; hypoxia inducible factor 1; immunoglobulin enhancer binding protein; mammalian target of rapamycin; Myc protein; phosphatidylinositol 3 kinase; phosphatidylinositol 3,4,5 trisphosphate 3 phosphatase; protein kinase B; protein p53; pyruvate kinase; pyruvate kinase M2; reduced nicotinamide adenine dinucleotide phosphate; unclassified drug; alternative RNA splicing; apoptosis; article; cancer metabolism; cancer prognosis; cell metabolism; cell proliferation; computer model; computer prediction; fatty acid synthesis; functional proteomics; gene expression regulation; gene overexpression; gene targeting; glucose transport; glycolysis; human; liquid chromatography; liquid chromatography multiple reaction monitoring; malignant neoplastic disease; metabolic rate; metabolism; monitoring; nonhuman; nucleic acid synthesis; priority journal; protein protein interaction; tumor microenvironment; Warburg effect

Metal mesh heating element size effect in resistance welding of thermoplastic composites - Dubé, M.; Hubert, P.; Gallet, J.N.A.H.; Stavrov, D.; Bersee, H.E.N.; Yousefpour, A. (Journal of Composite Materials, 2012)
The objective of this work is to determine the effects of metal mesh heating element size on resistance welding of thermoplastic composites. The materials to be resistance-welded consisted of carbon fiber/poly-ether-ketone- ketone (CF/PEKK), carbon fiber/poly-ether-imide (CF/PEI) and glass fiber/PEI (GF/PEI). Four different metal mesh sizes were used as heating elements. The samples were welded in a lap shear joint configuration and mechanically tested. Maximum Lap Shear Strengths of 52, 47 and 33 MPa were obtained for the CF/PEKK, CF/PEI and GF/PEI specimens, respectively. The ratio of the heating element's fraction of open area and wire diameter was shown to be the most important parameter to be considered when selecting an appropriate heating element size. © The Author(s) 2011.
Keywords: Joints/joining; Lap shear; Lap shear strength; Metal mesh; Size effects; Thermoplastic composite; Wire diameter; Composite materials; Ethers; Ketones; Organic compounds; Polymer matrix composites; Resistance welding; Thermoplastics; Welding; Electric heating elements; Composites; Electric Heating; Ethers; Joining; Joints; Ketones; Thermoplastics; Welding

Impact of initial surface parameters on the final quality of laser micro-polished surfaces - Chow, M.; Bordatchev, E.V.; Knopf, G.K. (Progress in Biomedical Optics and Imaging - Proceedings of SPIE, 2012)
Laser micro-polishing (LμP) is a new laser-based microfabrication technology for improving surface quality during a finishing operation and for producing parts and surfaces with near-optical surface quality. The LμP process uses low power laser energy to melt a thin layer of material on the previously machined surface. The polishing effect is achieved as the molten material in the laser-material interaction zone flows from the elevated regions to the local minimum due to surface tension. This flow of molten material then forms a thin ultra-smooth layer on the top surface. The LμP is a complex thermo-dynamic process where the melting, flow and redistribution of molten material is significantly influenced by a variety of process parameters related to the laser, the travel motions and the material. The goal of this study is to analyze the impact of initial surface parameters on the final surface quality. Ball-end micromilling was used for preparing initial surface of samples from H13 tool steel that were polished using a Q-switched Nd:YAG laser. The height and width of micromilled scallops (waviness) were identified as dominant parameter affecting the quality of the LμPed surface. By adjusting process parameters, the Ra value of a surface, having a waviness period of 33 μm and a peak-to-valley value of 5.9 μm, was reduced from 499 nm to 301 nm, improving the final surface quality by 39.7%. © 2012 SPIE.
Keywords: Experimental analysis; Finishing operation; H13 tool steel; Initial surface microgeometry; Laser-material interactions; Local minimums; Low power laser; Machined surface; Micro milling; Micro-fabrication technology; Polishing effects; Process parameters; Q switched Nd:YAG laser; Surface parameter; Thin layers; Top surface; Waviness; Composite micromechanics; Microanalysis; Microfabrication; Micromachining; Molten materials; Polishing; Surface roughness; Surface tension; Tool steel; Surfaces

Solubility and stability engineering of human VH domains - Kim, D.Y.; Ding, W.; Tanha, J. (Methods in Molecular Biology, 2012)
Solubility and stability are amongst the factors contributing to the therapeutic efficacy of biologics. Human antibody heavy chain variable domains, VHs, are one class of biologics; improving VH biophysical properties is the focus of significant protein engineering efforts. Here, we describe an efficacy engineering approach which involves the introduction of a disulfide linkage in the VH core and which improves both VH solubility and stability. More specifically, we describe protocols for generation of disulfide engineered human VHs and their characterization in terms of disulfide linkage formation, non-aggregation, and stability. Our solubility/stability engineering approach may be applied to other VHs. © 2012 Springer Science+Business Media, LLC.
Keywords: antibody; unclassified drug; vh antibody; disulfide; nanobody; article; priority journal; protein engineering; protein stability; solubility; amino acid sequence; chemistry; complementarity determining region; gene expression; genetics; human; isolation and purification; molecular cloning; molecular genetics; mutation; plasmid; protein engineering; temperature; Amino Acid Sequence; Cloning, Molecular; Complementarity Determining Regions; Disulfides; Gene Expression; Humans; Molecular Sequence Data; Mutation; Plasmids; Protein Engineering; Protein Stability; Single-Domain Antibodies; Solubility; Temperature

On liquation and liquid phase oxidation during linear friction welding of nickel-base in 738 and CMSX 486 superalloys - Amegadzie, M.Y.; Ola, O.T.; Ojo, O.A.; Wanjara, P.; Chaturvedi, M.C. (Proceedings of the International Symposium on Superalloys, 2012)
A systematic study of the microstructural response of conventionally cast IN 738 and single crystal CMSX 486 superalloys during linear friction welding was performed. The results revealed that, aside from a significant liquation of various phases that occurred during joining, continuous oxide films formed on the weld lines in both materials. The weld line oxides consisted of aluminum-rich and hafnium-base oxides in IN 738 and CMSX 486 superalloys, respectively, which can be deleterious to the mechanical properties of the weld joint. Gleeble thermo-mechanical simulation showed that the oxides were produced by the oxidation of some liquid exposed to atmospheric oxygen at the mating surfaces of the work pieces. A practicable method of eliminating liquid phase oxidation during linear friction welding of nickel-base superalloys is discussed.
Keywords: Atmospheric oxygen; Conventionally casts; Linear friction welding; Liquation; Liquid-phase oxidation; Micro-structural; Nickel base superalloy; Thermomechanical simulation; Compressive stress; Friction welding; Liquids; Mechanical properties; Nickel; Oxidation; Oxide films; Thermomechanical treatment; Welds; Superalloys

A novel method to prepare pet nanocomposites by water-assisted melt compounding - Dini, M.; Carreau, P.J.; Mousavand, T.; Kamal, M.R.; Ton-That, M.-T. (Annual Technical Conference - ANTEC, Conference Proceedings, 2012)
Polyethylene terephthalate (PET) nanocomposites were prepared via melt compounding of PET using a twin screw extruder. Water was fed to the extruder to assist in intercalation/exfoliation. The ratio between the water and PET feed rates was varied and Cloisite Na +, Cloisite 30B and Nanomer I.238E were used. Wide angle x-ray diffraction (XRD), scanning electron microscopy (SEM), differential scanning calorimetry (DSC) and rheometry were used to characterize the PET nanocomposites.
Keywords: Cloisite; Feed-rates; Melt-compounding; Rheometry; Twin screw extruders; Wide angle Xray diffraction; Differential scanning calorimetry; Plastic products; Polyethylene terephthalates; Scanning electron microscopy; Sodium; X ray diffraction; Nanocomposites

Herzberg Institute of Astrophysics' vibration measurement capabilities with applications to astronomical instrumentation - Byrnes, P. W. G. (Ground-Based and Airborne Telescopes IV, 2012)
The Herzberg Institute of Astrophysics, Astronomy Technology Research Group's vibration measurement capabilities include modal test via impulse hammer or electrodynamic exciter, structural response monitoring via piezoelectric accelerometers, and data acquisition via LabVIEW virtual instruments. This paper will review our existing capabilities, and give examples of past and future applications relevant to astronomical instrumentation. © 2012 SPIE.
Keywords: Astronomical instrumentation; Electrodynamic exciters; Future applications; Impulse hammers; LabVIEW virtual instrument; Modal test; Piezo-electric accelerometers; Structural response; Technology research; Vibration test; Airborne telescopes; Instruments; Modal analysis; Vibration measurement; Astrophysics

Functional control of the Candida albicans cell wall by catalytic protein kinase A subunit Tpk1 - Fanning, S.; Xu, W.; Beaurepaire, C.; Suhan, J.P.; Nantel, A.; Mitchell, A.P. (Molecular Microbiology, 2012)
The cyclic AMP protein kinase A pathway governs numerous biological features of the fungal pathogen Candida albicans. The catalytic protein kinase A subunits, Tpk1 (orf19.4892) and Tpk2 (orf19.2277), have divergent roles, and most studies indicate a more pronounced role for Tpk2. Here we dissect two Tpk1-responsive properties: adherence and cell wall integrity. Homozygous tpk1/tpk1 mutants are hyperadherent, and a Tpk1 defect enables biofilm formation in the absence of Bcr1, a transcriptional regulator of biofilm adhesins. A quantitative gene expression-based assay reveals that tpk1/tpk1 and bcr1/bcr1 genotypes show mixed epistasis, as expected if Tpk1 and Bcr1 act mainly in distinct pathways. Overexpression of individual Tpk1-repressed genes indicates that cell surface proteins Als1, Als2, Als4, Csh1 and Csp37 contribute to Tpk1-regulated adherence. Tpk1 is also required for cell wall integrity, but has no role in the gene expression response to cell wall inhibition by caspofungin. Interestingly, increased expression of the adhesin gene ALS2 confers a cell wall defect, as manifested in hypersensitivity to the cell wall inhibitor caspofungin and a shallow cell wall structure. Our findings indicate that Tpk1 governs C.albicans cell wall properties through repression of select cell surface protein genes. © 2012 Blackwell Publishing Ltd.
Keywords: caspofungin; cell protein; cell surface protein; cyclic AMP dependent protein kinase catalytic subunit; protein Als1; protein Als2; protein Als4; protein Csh1; protein Csp37; protein Tpk1; unclassified drug; antibiotic sensitivity; article; bacterial cell wall; bacterium adherence; biofilm; Candida albicans; cell adhesion; cell wall; controlled study; gene expression; gene function; gene identification; gene repression; genetic epistasis; genetic regulation; homozygosity; nonhuman; nucleotide sequence; priority journal; repressor gene; Tpk1 gene; transcription regulation; Biofilms; Candida albicans; Cell Wall; Cyclic AMP-Dependent Protein Kinase Catalytic Subunits; Fungal Proteins; Gene Expression Regulation, Fungal; Candida albicans

Extrusion foaming behavior of pet - Barzegari, M.R.; Hossieny, N.; Keshkar, M.; Chapleau, N.; Park, C.B. (Annual Technical Conference - ANTEC, Conference Proceedings, 2012)
The extrusion foaming behavior of polyethylene terephthalate (PET) with CO 2 was evaluated. The foaming morphologies of PET/nanocomposites and PET/chain extenders were also assessed. The foamed extrudates were analyzed for expansion ratio, cell structure, and degree of crystallinity using scanning electron microscopy (SEM) and differential scanning calorimetry (DSC). Finally, the effect of the die temperature on the cell structure of the PET foam samples was studied.
Keywords: Cell structure; Chain extenders; Degree of crystallinity; Die temperatures; Expansion ratio; Extrudates; Extrusion foaming; Carbon dioxide; Differential scanning calorimetry; Nanocomposites; Plastic products; Polyethylene terephthalates; Scanning electron microscopy; Foams

Blunted epidermal L-tryptophan metabolism in vitiligo affects immune response and ROS scavenging by Fenton chemistry, Part 2: Epidermal H 2O2/ONOO--mediated stress in vitiligo hampers indoleamine 2,3-dioxygenase and aryl hydrocarbon receptor-mediated immune response signaling - Schallreuter, K.U.; Salem, M.A.E.L.; Gibbons, N.C.J.; Maitland, D.J.; Marsch, E.; Elwary, S.M.A.; Healey, A.R. (FASEB Journal, 2012)
Vitiligo is characterized by a mostly progressive loss of the inherited skin color. The cause of the disease is still unknown, despite accumulating in vivo and in vitro evidence of massive oxidative stress via hydrogen peroxide (H2O2) and peroxynitrite (ONOO-) in the skin of affected individuals. The most favored hypothesis is based on autoimmune mechanisms. Since depletion of the essential amino acid L-tryptophan (Trp) severely affects various immune responses, we here looked at Trp metabolism and signaling in these patients. Our in vivo and in vitro data revealed total absence of epidermal Trp hydroxylase activities and the presence of H 2O2/ONOO- deactivated indoleamine 2,3-dioxygenase. Aryl hydrocarbon receptor signaling is severely impaired despite the ligand (Trp dimer) being formed, as shown by mass spectrometry. Loss of this signal is supported by the absence of downstream signals (COX-2 and CYP1A1) as well as regulatory T-lymphocytes and by computer modeling. In vivo Fourier transform Raman spectroscopy confirmed the presence of Trp metabolites together with H2O2 supporting deprivation of the epidermal Trp pool by Fenton chemistry. Taken together, our data support a long-expressed role for in loco redox balance and a distinct immune response. These insights could open novel treatment strategies for this disease. © FASEB.
Keywords: aromatic hydrocarbon receptor; cyclooxygenase 2; cytochrome P450 1A1; hydrogen peroxide; indoleamine 2,3 dioxygenase; peroxynitrite; reactive oxygen metabolite; tryptophan; tryptophan hydroxylase; adult; article; clinical article; controlled study; Fenton reaction; Fourier transform mass spectrometry; human; immune response; in vitro study; in vivo study; mass spectrometry; priority journal; Raman spectrometry; regulatory T lymphocyte; stress; vitiligo; Computer Simulation; Epidermis; Humans; Hydrogen Peroxide; Indoleamine-Pyrrole 2,3,-Dioxygenase; Oxidative Stress; Peroxynitrous Acid; Receptors, Aryl Hydrocarbon; Signal Transduction; T-Lymphocytes, Regulatory; Tryptophan; Vitiligo

Unfolding linac photon spectra and incident electron energies from experimental transmission data, with direct independent validation - Ali, E.S.M.; McEwen, M.R.; Rogers, D.W.O. (Medical Physics, 2012)
Purpose: In a recent computational study, an improved physics-based approach was proposed for unfolding linac photon spectra and incident electron energies from transmission data. In this approach, energy differentiation is improved by simultaneously using transmission data for multiple attenuators and detectors, and the unfolding robustness is improved by using a four-parameter functional form to describe the photon spectrum. The purpose of the current study is to validate this approach experimentally, and to demonstrate its application on a typical clinical linac. Methods: The validation makes use of the recent transmission measurements performed on the Vickers research linac of National Research Council Canada. For this linac, the photon spectra were previously measured using a NaI detector, and the incident electron parameters are independently known. The transmission data are for eight beams in the range 10-30 MV using thick Be, Al and Pb bremsstrahlung targets. To demonstrate the approach on a typical clinical linac, new measurements are performed on an Elekta Precise linac for 6, 10 and 25 MV beams. The different experimental setups are modeled using EGSnrc, with the newly added photonuclear attenuation included. Results: For the validation on the research linac, the 95 confidence bounds of the unfolded spectra fall within the noise of the NaI data. The unfolded spectra agree with the EGSnrc spectra (calculated using independently known electron parameters) with RMS energy fluence deviations of 4.5. The accuracy of unfolding the incident electron energy is shown to be ∼3. A transmission cutoff of only 10 is suitable for accurate unfolding, provided that the other components of the proposed approach are implemented. For the demonstration on a clinical linac, the unfolded incident electron energies and their 68 confidence bounds for the 6, 10 and 25 MV beams are 6.1 ± 0.1, 9.3 ± 0.1, and 19.3 ± 0.2 MeV, respectively. The unfolded spectra for the clinical linac agree with the EGSnrc spectra (calculated using the unfolded electron energies) with RMS energy fluence deviations of 3.7. The corresponding measured and EGSnrc-calculated transmission data agree within 1.5, where the typical transmission measurement uncertainty on the clinical linac is 0.4 (not including the uncertainties on the incident electron parameters). Conclusions: The approach proposed in an earlier study for unfolding photon spectra and incident electron energies from transmission data is accurate and practical for clinical use. © 2012 American Association of Physicists in Medicine.
Keywords: article; electron; human; methodology; Monte Carlo method; photon; reproducibility; spectroscopy; statistics; Electrons; Humans; Monte Carlo Method; Photons; Reproducibility of Results; Spectrum Analysis; Statistics as Topic

Evaluation of brain tumor vessels specific contrast agents for glioblastoma imaging - Tomanek, B.; Iqbal, U.; Blasiak, B.; Abulrob, A.; Albaghdadi, H.; Matyas, J.R.; Ponjevic, D.; Sutherland, G.R. (Neuro-Oncology, 2012)
A mouse model of glioblastoma multiforme was used to determine the accumulation of a targeted contrast agent in tumor vessels. The contrast agent, consisting of superparamagnetic iron oxide coated with dextran, was functionalized with an anti-insulin-like-growth-factor binding protein 7 (anti-IGFBP7) single domain antibody. The near infrared marker, Cy5.5, was also attached for an in vivo fluorescence study. A 9.4T magnetic resonance imaging (MRI) system was used for in vivo studies on days 10 and 11 following tumor inoculation. T2 relaxation time was used to measure the accumulation of the contrast agent in the tumor. Changes in tumor to brain contrast because of active targeting were compared with a nontargeted contrast agent. Effective targeting was confirmed with near infrared measurements and fluorescent microscopic analysis. The results showed that there was a statistically significant (P < .01) difference in normalized T2 between healthy brain and tumor tissue 10 min, 1 h, and 2 h point postinjection of the anti-IGFBP7 single domain antibody targeted and nontargeted iron oxide nanoparticles. A statistical difference remained in animals treated with targeted nanoparticles 24 h postinjection only. The MRI, near infrared imaging, and fluorescent microscopy studies showed corresponding spatial and temporal changes. We concluded that the developed anti-IGFBP7-iron oxide single domain antibodytargeted MRI contrast agent selectively binds to abnormal vessels within a glioblastoma. T2-weighted MRI and near infrared imaging are able to detect the targeting effects in brain tumors. © The Author(s) 2011.
Keywords: binding protein; contrast medium; dextran; growth factor; nuclear magnetic resonance imaging agent; superparamagnetic iron oxide; vascular targeting agent; animal experiment; animal model; animal tissue; article; brain blood vessel; brain tumor; cancer tissue; controlled study; fluorescence microscopy; glioblastoma; in vivo study; infrared radiation; inoculation; male; mouse; near infrared spectroscopy; nonhuman; nuclear magnetic resonance imaging; relaxation time; Animals; Antibodies; Brain Neoplasms; Cell Line, Tumor; Contrast Media; Dextrans; Ferric Compounds; Glioblastoma; Humans; Insulin-Like Growth Factor Binding Proteins; Magnetic Resonance Imaging; Male; Mice; Mice, Nude; Microscopy, Fluorescence; Nanoparticles

In Vitro and in Vivo biological activities of iron chelators and gallium nitrate against Acinetobacter baumannii - De Léséleuc, L.; Harris, G.; KuoLee, R.; Chen, W. (Antimicrobial Agents and Chemotherapy, 2012)
We investigated the ability of compounds interfering with iron metabolism to inhibit the growth of Acinetobacter baumannii. Iron restriction with transferrin or 2,2-bipyridyl significantly inhibited A. baumannii growth in vitro. Gallium nitrate alone was moderately effective at reducing A. baumannii growth but became bacteriostatic in the presence of serum or transferrin. More importantly, gallium nitrate treatment reduced lung bacterial burdens in mice. The use of gallium-based therapies shows promise for the control of multidrug-resistant A. baumannii. Copyright © 2012, American Society for Microbiology. All Rights Reserved.
Keywords: 2,2' bipyridine; chelating agent; gallium nitrate; transferrin; Acinetobacter baumannii; animal experiment; article; bacterial growth; bacterial load; bacteriostasis; controlled study; growth inhibition; in vitro study; in vivo study; iron metabolism; iron restriction; mouse; nonhuman; priority journal; 2,2'-Dipyridyl; Acinetobacter baumannii; Acinetobacter Infections; Animals; Gallium; Iron Chelating Agents; Mice; Transferrin

Dopant depletion in the near surface region of thermally prepared silicon (100) in UHV - Pitters, J.L.; Piva, P.G.; Wolkow, R.A. (Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, 2012)
Degenerately doped (arsenic) n-type hydrogen terminated silicon (100) samples were prepared using various heat treatments for ultrahigh vacuum scanning tunneling microscopy (STM) and spectroscopy (STS) analysis. Samples heat treated to 1050 C were found to have a consistent level of doping throughout the bulk and near surface regions. STS revealed tunneling through dopant states consistent with degenerately doped samples. SIMS profiling and HREELS measurements confirmed dopant and carrier concentrations, respectively. Samples heated to 1250 C were found to have a reduced concentration of dopants in the near surface region. STS measurements showed shifted I/V curves and the loss of tunneling through dopant states in the band gap, indicating reduced dopant concentrations. Observations were confirmed by SIMS and HREELS where depleted dopants and reduced carrier concentrations were measured. The effect of the varying surface dopant concentrations on the STM imaging characteristics of dangling bonds on hydrogen terminated surfaces was also investigated. Understanding the effect of thermal processing on near surface dopant atom concentrations will permit better control over equilibrium charge occupation and charging characteristics of dangling bond midgap states on H:silicon. © 2012 American Vacuum Society.
Keywords: Charging characteristics; Dopant atoms; Dopant concentrations; Dopant state; Doped sample; Hydrogen-terminated silicon; Hydrogen-terminated surfaces; Imaging characteristics; Near surface regions; Near-surface; Silicon (100); Ultrahigh vacuum scanning tunneling microscopies; Arsenic; Carrier concentration; Dangling bonds; Electric charge; Hydrogen; Scanning tunneling microscopy; Semiconductor doping

Optical and infrared photometry of globular clusters in NGC1399: Evidence for color-metallicity nonlinearity - Blakeslee, J.P.; Cho, H.; Peng, E.W.; Ferrarese, L.; Jordn, A.; Martel, A.R. (The Astrophysical Journal, 2012)
We combine new Wide Field Camera 3 IR Channel (WFC3/IR) F160W (H 160) imaging data for NGC1399, the central galaxy in the Fornax cluster, with archival F475W (g 475), F606W (V 606), F814W (I 814), and F850LP (z 850) optical data from the Advanced Camera for Surveys (ACS). The purely optical g 475 - I 814, V 606 - I 814, and g 475 - z 850 colors of NGC1399's rich globular cluster (GC) system exhibit clear bimodality, at least for magnitudes I 814 > 21.5. The optical-IR I 814 - H 160 color distribution appears unimodal, and this impression is confirmed by mixture modeling analysis. The V 606 - H 160 colors show marginal evidence for bimodality, consistent with bimodality in V 606 - I 814 and unimodality in I 814 - H 160. If bimodality is imposed for I 814 - H 160 with a double Gaussian model, the preferred blue/red split differs from that for optical colors; these "differing bimodalities" mean that the optical and optical-IR colors cannot both be linearly proportional to metallicity. Consistent with the differing color distributions, the dependence of I 814 - H 160 on g 475 - I 814 for the matched GC sample is significantly nonlinear, with an inflection point near the trough in the g 475 - I 814 color distribution; the result is similar for the I 814 - H 160 dependence on g 475 - z 850 colors taken from the ACS Fornax Cluster Survey. These g 475 - z 850 colors have been calibrated empirically against metallicity; applying this calibration yields a continuous, skewed, but single-peaked metallicity distribution. Taken together, these results indicate that nonlinear color-metallicity relations play an important role in shaping the observed bimodal distributions of optical colors in extragalactic GC systems. © 2012. The American Astronomical Society. All rights reserved.

Variability and change in the Canadian cryosphere - Derksen, C.; Smith, S.L.; Sharp, M.; Brown, L.; Howell, S.; Copland, L.; Mueller, D.R.; Gauthier, Y.; Fletcher, C.G.; Tivy, A.; Bernier, M.; Bourgeois, J.; et al. (Climatic Change, 2012)
During the International Polar Year (IPY), comprehensive observational research programs were undertaken to increase our understanding of the Canadian polar cryosphere response to a changing climate. Cryospheric components considered were snow, permafrost, sea ice, freshwater ice, glaciers and ice shelves. Enhancement of conventional observing systems and retrieval algorithms for satellite measurements facilitated development of a snapshot of current cryospheric conditions, providing a baseline against which future change can be assessed. Key findings include: 1. surface air temperatures across the Canadian Arctic exhibit a warming trend in all seasons over the past 40 years. A consistent pan-cryospheric response to these warming temperatures is evident through the analysis of multi-decadal datasets; 2. in recent years (including the IPY period) a higher rate of change was observed compared to previous decades including warming permafrost, reduction in snow cover extent and duration, reduction in summer sea ice extent, increased mass loss from glaciers, and thinning and break-up of the remaining Canadian ice shelves. These changes illustrate both a reduction in the spatial extent and mass of the cryosphere and an increase in the temporal persistence of melt related parameters. The observed changes in the cryosphere have important implications for human activity including the close ties of northerners to the land, access to northern regions for natural resource development, and the integrity of northern infrastructure. © 2012 UKCrown: Environment Canada; © Her Majesty the Queen in Right of Canada.
Keywords: Canadian Arctic; Changing climate; Cryosphere; Data sets; Freshwater ice; Human activities; Ice shelves; International polar year; Mass loss; Northern regions; Observational research; Observing systems; Rate of change; Resource development; Retrieval algorithms; Satellite measurements; Sea ice extent; Snow cover extents; Spatial extent; Surface air temperatures; Temporal persistence; Permafrost; Sea ice; Snow; air temperature; algorithm; cryosphere; data set; human activity; ice breakup; ice shelf; natural resource; permafrost; research program; resource development; satellite imagery; sea ice; snow cover; Canada

Expression of single-domain antibodies in bacterial systems - Baral, T.N.; Arbabi-Ghahroudi, M. (Methods in Molecular Biology, 2012)
In this chapter we describe in detail the current protocols that are used to express single-domain antibodies in bacteria. Bacteria are among the most common expression systems for expressing recombinant proteins. We present different approaches for carrying out periplasmic and cytoplasmic expression, as well as small-scale and large-scale expression. In addition, we discuss the advantages and possible drawbacks of each protocol. We present data related to expression vectors, expression conditions, methods of protein extraction and purification, and yield and purity analysis of sdAbs. We also highlight important points that need to be considered before sdAbs that have been expressed in bacteria are used either in vitro or in vivo. © 2012 Springer Science+Business Media, LLC.
Keywords: nanobody; recombinant antibody; hybrid protein; antibody library; antibody production; article; bacterium; culture medium; cytoplasm; Escherichia coli; expression vector; gene expression system; heavy chain; molecular cloning; nonhuman; phage display; priority journal; procedures; protein domain; protein expression; protein isolation; protein purification; reproducibility; antibody affinity; gene expression; gene library; gene vector; genetics; immunology; isolation and purification; metabolism; Antibody Affinity; Bacteria; Cloning, Molecular; Escherichia coli; Gene Expression; Gene Library; Genetic Vectors; Recombinant Fusion Proteins; Single-Domain Antibodies

New concepts in silicon component design using sub wavelength structures - Molina-Fernandez, Iñigo; Halir, Robert; Ortega-Moñux, Alejandro; Zavargo-Peche, Luis; García, Sebastian Romero; Maese-Novo, Alejandro; Perez-Galacho, Diego; Wanguemert-Perez, Gonzalo; Cheben, Pavel; Xu, Dan-Xia (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Subwavelength gratings (SWG) are periodically segmented waveguides with a pitch small enough to suppress diffraction. These waveguides can be engineered to implement almost any refractive between the refractive indices of the material that compose the waveguide, thereby opening novel design possibilities. In this communication we explore the use of SWGs in the design and optimization of a variety of integrated optical devices in the silicon-on-insulator platform: fiber-to-chip grating couplers, polarization splitters and high performance multimode interference couplers. We furthermore show that the dispersion properties of SWGs enable the design of novel filters, and discuss the design of low transitions between SWG waveguides of different characteristics. © 2012 SPIE.
Keywords: Grating couplers; Multimode interference couplers; Polarization splitters; Silicon on insulator; Sub-wave length grating; SWG tapers; Design; Integrated optics; Optical filters; Photonic devices; Polarization; Refractive index; Waveguides; Waveguide filters

Impact of room supply register location on predicted thermal comfort and IAQ - Ouazia, B.; MacDonald, I.; Thompson, A.; Booth, D. (International Journal of Ventilation, 2012)
For residential forced air heating and cooling systems conventional thinking is that air supply registers should be located under exterior windows. There were good reasons for this in the past (primarily to counteract the cold downdraught from the window) but new construction standards (well-insulated walls, better glazing and air tight wall/window interface) mean that there is now less downdraught. Positioning the supply air register away from a window could have a large impact for new construction as duct lengths could be shortened (saving materials and construction time). This could also allow greater architectural freedom as the forced air system would not need to be ducted to the building perimeter. This paper presents results from experiments conducted in a new, well-constructed building to evaluate whether the supply registers can be moved away from the traditional location without impacting indoor air quality or predicted thermal comfort. The physical experiments showed that in both traditional and non-traditional placement: (1) there are minimal changes in predicted thermal comfort (a measure of thermal discomfort - vertical air temperature difference much lower than 3K), and (2) contaminant-removal effectiveness (a measure of indoor air quality) values were in the same range.
Keywords: Air heating; Air supply; Air Systems; Air temperature; Construction time; IAQ; Indoor air quality; New constructions; Residential; Tracer gas; Indoor air pollution; Thermal comfort; Phase interfaces

The effect of total spinal anesthesia on cardiac function in a large animal model of brain death - Almoustadi, W.A.; Lee, T.W.R.; Klein, J.; Kumar, K.; Arora, R.C.; Tian, G.; Freed, D.H. (Canadian Journal of Physiology and Pharmacology, 2012)
Brain death (BD) causes cardiac dysfunction in organ donors, attributable to the catecholamine storm that occurs with raised intracerebral pressure (ICP). However the direct contribution of the spinal sympathetics has not been well described. We examined the effect of total spinal anesthesia (TSA) on cardiac function in a large animal model of BD. Eighteen pigs were allocated to 3 experimental groups: Group 1, the saline-treated control group; Group 2, TSA administered prior to BD; and Group 3, TSA administered 30 min after BD. Inflation of an intracerebral balloon-tipped catheter was used to induce BD. Ventricular function was assessed using a pressure-volume loop catheter and magnetic resonance imaging. Serum catecholamine levels were assessed with high performance liquid chromatography. Inflation of the intracerebral balloon-tipped catheter was associated with a dramatic rise in heart rate and blood pressure, along with increased concentrations of serum epinephrine and norepinephrine. This phenomenon was not observed in Group 2. In Group 1, there was a significant decline in contractility, whereas groups 2 and 3 saw no change. Group 2 had greater contractile reserve than groups 1 and 3. Our data demonstrate the central role of spinal sympathetics in the hemodynamic response to raised ICP. Further work is required to determine the utility of TSA in reversing cardiac dysfunction in BD donors.
Keywords: adrenalin; catecholamine; noradrenalin; sodium chloride; adrenalin blood level; animal experiment; animal model; article; balloon catheter; blood pressure; brain death; catecholamine blood level; controlled study; heart function; heart rate; high performance liquid chromatography; intracerebral balloon tipped catheter; nonhuman; noradrenalin blood level; nuclear magnetic resonance imaging; priority journal; spinal anesthesia; swine; total spinal anesthesia

Extracting functionally feed forward networks from a population of spiking neurons - Vincent, K.; Tauskela, J.S.; Thivierge, J.-P. (Frontiers in Computational Neuroscience, 2012)
Neuronal avalanches are a ubiquitous form of activity characterized by spontaneous bursts whose size distribution follows a power-law. Recent theoretical models have replicated power-law avalanches by assuming the presence of functionally feedforward connections (FFCs) in the underlying dynamics of the system. Accordingly, avalanches are generated by a feedforward chain of activation that persists despite being embedded in a larger, massively recurrent circuit. However, it is unclear to what extent networks of living neurons that exhibit power-law avalanches rely on FFCs. Here, we employed a computational approach to reconstruct the functional connectivity of cultured cortical neurons plated on multielectrode arrays, and investigated whether pharmacologically-induced alterations in avalanche dynamics are accompanied by changes in FFCs. This approach begins by extracting a functional network of directed links between pairs of neurons, and then evaluates the strength of FFCs using Schur decomposition. In a first step, we examined the ability of this approach to extract FFCs from simulated spiking neurons. The strength of FFCs obtained in strictly feedforward networks diminished monotonically as links were gradually rewired at random. Next, we estimated the FFCs of spontaneously active cortical neuron cultures in the presence of either a control medium, a GABAA receptor antagonist (PTX), or an AMPA receptor antagonist combined with an NMDA receptor antagonist (APV/DNQX). The distribution of avalanche sizes in these cultures was modulated by this pharmacology, with a shallower power-law under PTX (due to the prominence of larger avalanches) and a steeper power-law under APV/DNQX (due to avalanches recruiting fewer neurons) relative to control cultures. The strength of FFCs increased in networks after application of PTX, consistent with an amplification of feed forward activity during avalanches. Conversely, FFCs decreased after application of APV/DNQX, consistent with fading feed forward activation. The observed alterations in FFCs provide experimental support for recent theoretical work linking power-law avalanches to the feed forward organization of functional connections in local neuronal circuits. © 2012 Vincent, Tauskela and Thivierge.
Keywords: AMPA-receptor; AS-links; Avalanche dynamics; Computational approach; Control cultures; Control mediums; Cortical neurons; Cultured cortical neurons; Directed links; Feed forward; Feed-forward network; Feedforward connections; Functional connection; Functional connectivity; Functional network; GABAA receptors; Multielectrode arrays; Neuronal circuits; NMDA receptor; Poisson model; Power-law; Schur decomposition; Spiking neuron; Theoretical models; Underlying dynamics; Dynamics; Neurons; Neural networks; animal cell; animal experiment; article; artificial neural network; cell structure; cellular distribution; controlled study; feedforward network; mathematical computing; mathematical model; nerve cell culture; nerve stimulation; nervous system function; neuromodulation; nonhuman; rat; spike wave

Transition path times for nucleic acid folding determined from energy-landscape analysis of single-molecule trajectories - Neupane, K.; Ritchie, D.B.; Yu, H.; Foster, D.A.N.; Wang, F.; Woodside, M.T. (Physical Review Letters, 2012)
The duration of structural transitions in biopolymers is only a fraction of the time spent searching diffusively over the configurational energy landscape. We found the transition time, τ TP, and the diffusion constant, D, for DNA and RNA folding using energy landscapes obtained from single-molecule trajectories under tension in optical traps. DNA hairpins, RNA pseudoknots, and a riboswitch all had τ TP∼10μs and D∼10 -13 -14m2/s, despite widely differing unfolding rates. These results show how energy-landscape analysis can be harnessed to characterize brief but critical events during folding reactions. © 2012 American Physical Society.
Keywords: Configurational energy; Critical events; Diffusion constant; DNA hairpin; Energy landscape; Folding reactions; Optical trap; Pseudo-knots; Riboswitches; RNA folding; Single-molecule; Structural transitions; Time spent; Transition paths; Transition time; Biopolymers; RNA; Molecules

Theory untangles the high-resolution infrared spectrum of the ortho-H 2-CO van der Waals complex - Jankowski, P.; McKellar, A.R.W.; Szalewicz, K. (Science, 2012)
Rovibrational spectroscopy of molecules boasts extremely high precision, but its usefulness relies on the assignment of spectral features to corresponding quantum mechanical transitions. In the case of ortho-H 2-CO, a weakly bound complex abundant in the interstellar medium (although not yet observed there), the rather complex spectrum has been unexplained for more than a decade. We assigned this spectrum by comparison with a purely ab initio calculation. For most lines, agreement to within 0.01 centimeter-1 between experiment and theory was achieved. Our results show that the applicability of rovibrational spectroscopy can be extended with the assistance of high-accuracy quantum mechanical computations.
Keywords: computer; infrared radiation; infrared spectroscopy; precision; quantum mechanics; spectrum; article; energy; infrared spectroscopy; priority journal; quantum mechanics; theory validation; vibration

Wavelength conversion via FWM in a silicon ring resonator at 10 Gb/s for DPSK signals - Li, F.; Pelusi, M.; Xu, D.-X.; Ma, R.; Janz, S.; Eggleton, B.J.; Moss, D.J. (2012 Conference on Lasers and Electro-Optics, CLEO 2012, 2012)
We demonstrate all-optical wavelength conversion at 10 Gb/s for differential phase-shift keyed (DPSK) data in the C-band, based on four-wave mixing (FWM) in a silicon ring resonator. Error-free operation with a system penalty of ∼ 4.1 dB at 10-9 BER is achieved. © 2012 OSA.
Keywords: 10 Gb/ S; All-optical wavelength conversion; DPSK signals; Error free operations; Silicon ring resonator; System penalty; Lasers; Light modulation; Optical frequency conversion; Four wave mixing

METAGENassist: A comprehensive web server for comparative metagenomics - Arndt, D.; Xia, J.; Liu, Y.; Zhou, Y.; Guo, A.C.; Cruz, J.A.; Sinelnikov, I.; Budwill, K.; Nesbø, C.L.; Wishart, D.S. (Nucleic Acids Research, 2012)
With recent improvements in DNA sequencing and sample extraction techniques, the quantity and quality of metagenomic data are now growing exponentially. This abundance of richly annotated metagenomic data and bacterial census information has spawned a new branch of microbiology called comparative metagenomics. Comparative metagenomics involves the comparison of bacterial populations between different environmental samples, different culture conditions or different microbial hosts. However, in order to do comparative metagenomics, one typically requires a sophisticated knowledge of multivariate statistics and/or advanced software programming skills. To make comparative metagenomics more accessible to microbiologists, we have developed a freely accessible, easy-to-use web server for comparative metagenomic analysis called METAGENassist. Users can upload their bacterial census data from a wide variety of common formats, using either amplified 16S rRNA data or shotgun metagenomic data. Metadata concerning environmental, culture, or host conditions can also be uploaded. During the data upload process, METAGENassist also performs an automated taxonomic-to-phenotypic mapping. Phenotypic information covering nearly 20 functional categories such as GC content, genome size, oxygen requirements, energy sources and preferred temperature range is automatically generated from the taxonomic input data. Using this phenotypically enriched data, users can then perform a variety of multivariate and univariate data analyses including fold change analysis, t-tests, PCA, PLS-DA, clustering and classification. To facilitate data processing, users are guided through a step-by-step analysis workflow using a variety of menus, information hyperlinks and check boxes. METAGENassist also generates colorful, publication quality tables and graphs that can be downloaded and used directly in the preparation of scientific papers. METAGENassist is available at http://www.metagenassist.ca. © 2012 The Author(s).
Keywords: RNA 16S; article; automation; bacterial genome; bacterium culture; classification; cluster analysis; comparative metagenomics; comparative study; computer program; controlled study; data processing; energy resource; environment; genetic database; genome size; host; intermethod comparison; Internet; metagenomics; nonhuman; nucleotide sequence; oxygen consumption; phenotype; population genetics; priority journal; publication; statistical analysis; taxonomy; temperature; web server; Bacteria; Data Interpretation, Statistical; Internet; Metagenomics; Phenotype; Software; Bacteria (microorganisms)

The instrumentation program for the Thirty Meter Telescope - Simard, L.; Crampton, D.; Ellerbroek, B.; Boyer, C. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
An overview of the current status of the Thirty Meter Telescope (TMT) instrumentation program is presented. Science cases and operational concepts as well as their links to the instruments are continually revisited and updated through a series of workshops and conferences. Work on the three first-light instruments (WFOS IRIS, and IRMS) has made significant progress, and many groups in TMT partner communities are developing future instrument concepts. Other instrument-related subsystems are also receiving considerable attention given their importance to the scientific end-toend performance of the Observatory. As an example, we describe aspects of the facility instrument cooling system that are crucially important to successful diffraction-limited observations on an extremely large telescope. © 2012 SPIE.
Keywords: Current status; Diffraction limited; Extremely Large Telescopes; Instrumentation programs; Observation planning; Operational concepts; Thirty Meter Telescope; Adaptive optics; Astronomy; Telescopes; Optical telescopes

Dark hole and planet detection: Laboratory results using the Self-Coherent Camera - Baudoz, P.; Mazoyer, J.; Mas, M.; Galicher, R.; Rousset, G. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Direct imaging and low-resolution spectroscopy of extrasolar planets are exciting but challenging scientific applications of coronagraphy. While the angular separation is well within the reach of actual telescope in the near IR or visible, the planet-star contrast (from 10-6 to 10-10) requires wavefront quality and stability hard to reach even with a well-polished space telescope. Several solutions have been proposed to tackle the speckle noise introduced by the residual optical defects. While some concepts rely only on active wavefront correction using deformable mirror, other techniques are based on post-processing and subtract a reference image recorded sometimes simultaneously with the science image. One interesting solution is to choose a concept that allows both active correction and post-processing of high contrast coronagraphic images. This is the case of the Self Coherent Camera (SCC), which has been proposed for the project of space coronagraph SPICES and for the ground-based planet finder EPICS studied for the European Extremely Large Telescope. After recalling the SCC principle, we present both monochromatic and modest bandwidth (2%) experimental results of Dark Hole in the focal plane using a SCC. Example of a post-processing result with SCC is also given to emphasize the interest of combining it with active correction. © 2012 SPIE.
Keywords: Active correction; Angular separation; Coronagraph; Coronagraphy; Deformable mirrors; Direct imaging; Exoplanet; Extra solar planets; Extremely Large Telescopes; Focal Plane; Ground based; High contrast; High contrast imaging; Near-IR; Optical defects; Planet detection; Planet finders; Post processing; Reference image; Scientific applications; Speckle noise; Wavefront correction; Wavefront quality; Astronomy; Cameras; Laser pulses; Optical telescopes; Image processing

Gemini high-resolution optical spectrograph conceptual design - Szeto, K.; McConnachie, A.; Anthony, A.; Bohlender, D.; Crampton, D.; Desaulniers, P.; Dunn, J.; Hardy, T.; Hill, A.; Monin, D.; Pazder, J.; Schwab, C.; et al. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
A multiplexed moderate resolution (R = 34,000) and a single object high resolution (R = 90,000) spectroscopic facility for the entire 340-950nm wavelength region has been designed for Gemini. The result is a high throughput, versatile instrument that will enable precision spectroscopy for decades to come. The extended wavelength coverage for these relatively high spectral resolutions is achieved by use of an Echelle grating with VPH cross-dispersers and for the R = 90,000 mode utilization of an image slicer. The design incorporates a fast, efficient, reliable system for acquiring targets over the7 arcmin field of Gemini. This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study instrument group of the Herzberg Institute of Astrophysics has been commissioned by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the science case development and requirements flow-down process that leads to the configuration of the HIA instrument and describes the overall GHOS conceptual design. In addition, this paper discusses design trades examined during the conceptual design study. © 2012 SPIE.
Keywords: CCD detectors; Design trades; Echelle; Instrument software; Pick-off; White pupil relay; Astrophysics; Commerce; Conceptual design; Fibers; Motion control; Optical resolving power; Spectrographs; Instruments

Nonlinear behaviour of steel-concrete composite bridges: Finite element modelling and experimental verification - Razaqpur, A.G.; Nofal, M.; Shedid, M.; Esfandiari, A. (Canadian Journal of Civil Engineering, 2012)
To ensure public safety, existing bridges are often evaluated for their load-bearing capacity. Realistic evaluation must take into account the actual nonlinear stress-strain characteristics of the bridge materials and the interaction among its structural components at all stages of loading up to failure. The finite element method is particularly suitable for this type of analysis, but nonlinear finite element formulations involve many assumptions that must be verified before any practical application. In this study, the accuracy of a nonlinear finite element program developed by the authors for the analysis of composite steel-concrete bridges is checked by comparing its results with experimental data from simply supported and continuous beams tested by others and from a 1/3 scale multi-girder composite bridge tested by the authors. Good agreement is observed between the measured and the computed load-deflection responses and strains at all stages of loading up to the maximum load, which demonstrates the accuracy of the finite element formulation and the validity of its assumptions.
Keywords: Analysis; Composite; Finite Element; Load distributions; Reinforced; Bridges; Composite bridges; Concretes; Loading; Nonlinear analysis; Software testing; Steel; Finite element method; accuracy assessment; bridge; finite element method; loading; nonlinearity; reinforced concrete; steel structure; structural analysis

Development of robust control law for active buffeting load alleviation of smart fin structures - Chen, Y.; Ulker, F.D.; Wickramasinghe, V.; Zimcik, D. (23rd International Conference on Adaptive Structures and Technologies, ICAST 2012, 2012)
Aerodynamic buffeting load can lead to pre-mature fatigue damage of aircraft vertical fin structures. This paper presents a robust control law development strategy for active buffeting load alleviation of a smart fin structure. The impact of aerodynamic loads on the modeling uncertainties of the smart fin was investigated through extensive wind tunnel tests. Test results revealed that the airflow introduced higher damping ratio and caused frequency shift to the vibration modes. These aerodynamic effects may adversely affect the performance and robustness of active control laws. Based on the observations, the structured singular value synthesis technique was used to develop a robust control law for the smart fin using a truncated baseline dynamic model. A parametric uncertainty block was introduced to account for the changes in the modal parameters of the baseline dynamic model due to the aerodynamic effects. An additive uncertainty block was included to account for the un-modeled higher order vibration modes as well as the modeling errors in the low frequency range. The robust performance of the control law was demonstrated through simulations as well as extensive closed-loop control experiments in the wind tunnel using various free airstreams and vortical airflows. This provided a verified control law design strategy for active buffeting alleviation applications.
Keywords: Buffeting load; Development strategies; Low frequency range; Model uncertainties; Parametric uncertainties; Structured singular values; Synthesis techniques; Vertical fin; Buffeting; Dynamic models; Fins (heat exchange); Modal analysis; Robust control; Uncertainty analysis; Vibration control; Vertical stabilizers

Flocculation of cellulose nanocrystals by adsorbing and non-adsorbing polymers - Boluk, Y.; Danumah, C.; Khalili, Z. (TAPPI International Conference on Nanotechnology for Renewable Materials 2012, 2012)

Residual strain distribution around a fatigue-crack tip determined by neutron diffraction - Huang, E.-W.; Li, K.-W.; Lee, S.Y.; Woo, W.; Ding, Y.-S.; Tsay, L.-W.; Chen, C.-H. (Materials Science Forum, 2012)
An analysis of residual stress, one of the contributory factors to the crack tip driving force, is extremely important to probe the fatigue crack growth mechanism and to further develop the life prediction methodology. Since fatigue crack growth is governed by crack-tip plasticity and crack closure in the wake of the crack tip, the investigation of residual stain/stress field in both behind and in front of the crack tip is crucial. In the current work, a 304L stainless steel compact-tension specimen is pre-cracked under constant-amplitude cyclic loading. Neutron diffraction is employed to directly measure the three orthogonal residual strain fields with 1-mm spatial resolution as a function of distance from the crack tip. The mapping results show that the three orthogonal residual-strain distributions around the crack tip depend on the stress multiaxiality, not following a single Poisson relationship to each axis. © 2012 Trans Tech Publications, Switzerland.
Keywords: 304L stainless steel; Compact tension; Cyclic loadings; Driving forces; Fatigue crack growth mechanism; Life-prediction methodology; Multiaxiality; Residual strains; Spatial resolution; Crack propagation; Crack tips; Fatigue crack propagation; Fatigue of materials; Growth (materials); Neutron diffraction; Neutrons; Orthogonal functions; Plasticity testing; Poisson distribution; Stainless steel; Strain; Factor analysis; Crack closure; Crack tips

Application of dielectric barrier discharge to improve the flashback limit of a lean premixed dump combustor - Versailles, P.; Chishty, W.A.; Vo, H.D. (Journal of Engineering for Gas Turbines and Power, 2012)
In recent years, lean-premixed (LP) combustors have been widely studied due to their potential to reduce NO x emissions in comparison to diffusion type combustors. However, the fact that the fuels and oxidizers are mixed upstream of the combustion zone makes LP type of combustors a candidate for upstream flame propagation (i.e., flashback) in the premixer that is typically not designed to sustain high temperatures. Moreover, there has been a recent demand for fuel-flexible gas turbines that can operate on hydrogen-enriched fuels like Syngas. Combustors originally designed for slower kinetics fuels like natural gas can potentially encounter flashback if operated with faster burning fuels like those containing hydrogen as a constituent. There exists a clear need in fuel-flexible lean-premixed combustors to control flashback that will not only prevent costly component damage but will also enhance the operability margin of engines. A successful attempt has been made to control flashback in an atmospheric LP combustor, burning natural gas-air mixtures, via the application of dielectric barrier discharge (DBD). A low-power DBD actuator was designed, fabricated and integrated into a premixer made out of quartz. The actuator was tuned to produce a low magnitude ionic wind with an intention to modify the velocity profile in the premixer. Flashback conditions were created by decreasing the air flow rate while keeping the fuel flow rate constant. Within this experimental setup, flashback happened in the core flow along the axis of the cylindrical premixer. Results show that the utilization of the DBD delays the occurrence of flashback to higher equivalence ratios. Improvements as high as about 5 of the flashback limit have been obtained without compromising the blowout limit. It is anticipated that this novel application of DBD will lead to future demonstrations of the concept under realistic gas turbine operating conditions. © 2012 Her Majesty the Queen in Right of Canada.
Keywords: Air flow-rate; Combustion zones; Core flow; Dielectric barrier discharges; Dump combustor; Equivalence ratios; Experimental setup; Flame propagation; High temperature; Ionic wind; Low Power; Natural gas-air mixture; Novel applications; Operating condition; Premixed; Syn-gas; Velocity profiles; Actuators; Combustion; Dielectric devices; Flow control; Flow rate; Fuels; Gas turbines; Hydrogen; Natural gas; Quartz; Rate constants; Synthesis gas; Combustors

A literature review of the numerical analysis of abdominal aortic aneurysms treated with endovascular stent grafts - Roy, D.; Kauffmann, C.; Delorme, S.; Lerouge, S.; Cloutier, G.; Soulez, G. (Computational and Mathematical Methods in Medicine, 2012)
The purpose of this paper is to present the basic principles and relevant advances in the computational modeling of abdominal aortic aneurysms and endovascular aneurysm repair, providing the community with up-to-date state of the art in terms of numerical analysis and biomechanics. Frameworks describing the mechanical behavior of the aortic wall already exist. However, intraluminal thrombus nonhomogeneous structure and porosity still need to be well characterized. Also, although the morphology and mechanical properties of calcifications have been investigated, their effects on wall stresses remain controversial. Computational fluid dynamics usually assumes a rigid artery wall, whereas fluid-structure interaction accounts for artery compliance but is still challenging since arteries and blood have similar densities. We discuss alternatives to fluid-structure interaction based on dynamic medical images that address patient-specific hemodynamics and geometries. We describe initial stresses, elastic boundary conditions, and statistical strength for rupture risk assessment. Special emphasis is accorded to workflow development, from the conversion of medical images into finite element models, to the simulation of catheter-aorta interactions and stent-graft deployment. Our purpose is also to elaborate the key ingredients leading to virtual stenting and endovascular repair planning that could improve the procedure and stent-grafts. © 2012 David Roy et al.
Keywords: abdominal aorta aneurysm; aneurysm rupture; aorta wall; artery calcification; artery compliance; biomechanics; blood flow; blood rheology; endovascular aneurysm repair; finite element analysis; laminar flow; mathematical computing; mathematical model; review; shear stress; stress strain relationship; virtual reality; viscoelasticity; Young modulus; aorta; biological model; blood vessel; blood vessel transplantation; calcinosis; catheter; computer simulation; flow kinetics; hemodynamics; human; instrumentation; mechanical stress; methodology; pathology; risk; stent; theoretical model; Aorta; Aortic Aneurysm, Abdominal; Biomechanics; Blood Vessel Prosthesis Implantation; Blood Vessels; Calcinosis; Catheters; Computer Simulation; Finite Element Analysis; Hemodynamics; Humans; Models, Cardiovascular; Models, Theoretical; Rheology; Risk; Stents; Stress, Mechanical

A blind detection of a large, complex, Sunyaev-Zel'dovich structure - Shimwell, T.W.; Barker, R.W.; Biddulph, P.; Bly, D.; Boysen, R.C.; Brown, A.R.; Brown, M.L.; Clementson, C.; Crofts, M.; Culverhouse, T.L.; Czeres, J.; Dace, R.J.; et al. (Monthly Notices of the Royal Astronomical Society, 2012)
We present an interesting Sunyaev-Zel'dovich (SZ) detection in the first of the Arcminute Microkelvin Imager (AMI) 'blind', degree-square fields to have been observed down to our target sensitivity of. In follow-up deep pointed observations the SZ effect is detected with a maximum peak decrement greater than eight times the thermal noise. No corresponding emission is visible in the ROSAT all-sky X-ray survey and no cluster is evident in the Palomar all-sky optical survey. Compared with existing SZ images of distant clusters, the extent is large (≈10arcmin) and complex; our analysis favours a model containing two clusters rather than a single cluster. Our Bayesian analysis is currently limited to modelling each cluster with an ellipsoidal or spherical β model, which does not do justice to this decrement. Fitting an ellipsoid to the deeper candidate we find the following. (a) Assuming that the Evrard et al. approximation to Press & Schechter correctly gives the number density of clusters as a function of mass and redshift, then, in the search area, the formal Bayesian probability ratio of the AMI detection of this cluster is 7.9 × 10 4:1; alternatively assuming Jenkins et al. as the true prior, the formal Bayesian probability ratio of detection is 2.1 × 10 5:1. (b) The cluster mass is (c) Abandoning a physical model with number density prior and instead simply modelling the SZ decrement using a phenomenological β model of temperature decrement as a function of angular distance, we find a central SZ temperature decrement of K - this allows for cosmic microwave background primary anisotropies, receiver noise and radio sources. We are unsure if the cluster system we observe is a merging system or two separate clusters. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Optical design of a Cassegrain mounted AO relay for Imaka - Pazder, J. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
The Imaka project is a ground layer adaptive optics system proposed for the Canada-France-Hawaii Telescope. This paper presents the optical design of a Cassegrain mounted ground layer adaptive optics system with a 0.8 degree field of view for Imaka. The design incorporates a Takeshi concentric ADC and a f/8 to f/5.7 reducer. This is followed with a novel double pass system to image the pupil on a 300mm mildly concave deformable mirror and re-image the system on the detector. The design meets the required 0.15" 80% encircled energy image performance, including correction for atmospheric dispersion. The optical design is presented with the predicted imaging performance. © 2012 SPIE.
Keywords: Astronomical instrumentation; Atmospheric dispersion; Deformable mirrors; Double pass; Encircled energy; Field of views; Ground-layer adaptive optics; Image performance; Imaging performance; Takeshi ADC; Adaptive optics; Atmospheric movements; Optical telescopes; Telescopes; Optical design

Preserving the photometric integrity of companions in high-contrast imaging observations using locally optimized combination of images - Maire, J.; Gagné, J.; Lafrenière, D.; Doyon, R.; Graham, J.R.; Véran, J.-P.; Poyneer, L.A. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Direct imaging and spectroscopy can advance our understanding of planet formation and migration through the detection and characterization of extrasolar planets on wide orbits. Accurate photometry and astrometry of detected companions are of crucial importance to derive the planet physical properties.We present an extension of the Locally optimized combination of images (LOCI) method to measure the highest-fidelity photometry as well as accurate astrometry of detected companions. This algorithm is also generalized to Integral-Field Spectrograph (IFS) data processing, giving advantages of a simultaneous angular and spectral differential imaging reduction, retrieving high-fidelity spectra from PSF-subtracted cubes. © 2012 SPIE.
Keywords: Direct imaging; Exo-planets; Extra solar planets; High contrast imaging; Planet formation; Speckle suppression; Techniques; Data processing; Image processing; Optimization; Photometry

The JWST Fine Guidance Sensor (FGS) and Near-Infrared Imager and Slitless Spectrograph (NIRISS) - Doyon, R.; Hutchings, J.; Beaulieu, M.; Albert, L.; Lafrenière, D.; Willott, C.; Touahri, D.; Rowlands, N.; Maszkiewicz, M.; Fullerton, A.; Volk, K.; Martel, A.; et al. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
The Fine Guidance Sensor (FGS) is one of the four science instruments on board the JamesWebb Space Telescope (JWST). FGS features two modules: an infrared camera dedicated to fine guiding of the observatory and a science camera module, the Near-Infrared Imager and Slitless Spectrograph (NIRISS) covering the wavelength range between 0.7 and 5.0 μm with a field of view of 2.2'×2.2'. NIRISS has four observing modes: 1) broadband imaging featuring seven of the eight NIRCam broadband filters, 2) wide-field slitless spectroscopy at a resolving power of ̃150 between 1 and 2.5 μm, 3) single-object cross-dispersed slitless spectroscopy enabling simultaneous wavelength coverage between 0.7 and 2.5 μm at R ̃ 660, a mode optimized for transit spectroscopy of relatively bright (J > 7) stars and, 4) sparse aperture interferometric imaging between 3.8 and 4.8 μm enabling high- contrast (̃ 10-4) imaging of M < 8 point sources at angular separations between 70 and 500 milliarcsec. This paper presents an overview of the FGS/NIRISS design with a focus on the scientific capabilities and performance offered by NIRISS. © 2012 SPIE.
Keywords: Angular separation; Broadband filters; Broadband imaging; Exo-planets; Field of views; Fine guidance sensors; High contrast imaging; Infra-red cameras; Interferometric imaging; JWST instrumentation; Near Infrared; Point sources; Sparse aperture; Wavelength coverage; Wavelength ranges; Wide-field; Infrared devices; Interferometry; Millimeter waves; Sensors; Source separation; Space telescopes; Spectrographs; Spectroscopy; Instruments

Stable hydrogen storage cycling in magnesium hydride, in the range of room temperature to 300°C, achieved using a new bimetallic Cr-V nanoscale catalyst - Zahiri, B.; Danaie, M.; Tan, X.; Amirkhiz, B.S.; Botton, G.A.; Mitlin, D. (The Journal of Physical Chemistry C, 2012)
We created a bimetallic chromium vanadium hydrogen sorption catalyst for magnesium hydride (MgH 2). The catalyst allows for significant room-temperature hydrogen uptake, over 10 cycles, at absorption pressures as low as 2 bar. This is something that has never been previously achieved. The catalyst also allowed for ultrarapid and kinetically stable hydrogenation cycling (over 225 cycles) at 200 and at 300 °C. Transmission electron microscopy analysis of the postcycled samples revealed a nanoscale dispersion of Cr-V nanocrystallites within the Mg or MgH 2 matrix. TEM analysis of the partially absorbed specimens revealed that even at a high absorption pressure, that is, a high driving force, relatively few hydride nuclei are formed at the surface of the pre-existing magnesium, ruling out the presence of any contracting volume (also termed contracting envelope or core shell) type growth. HRTEM of the cycled and desorbed powder sample demonstrated that the bcc Cr-V phase is crystalline and nanoscale. We experimentally demonstrated that the activation energy for hydrogen absorption is not constant but rather evolves with the driving force. This finding sheds new insight regarding the origins of the wide discrepancy in the literature - reported values of the hydrogenation activation energy in magnesium hydride and in related metal hydride systems. © 2011 American Chemical Society.
Keywords: Core shell; Driving forces; Hydrogen absorption; Hydrogen sorption; Hydrogen uptake; Magnesium hydride; matrix; Metal hydride systems; Nano scale; Nanoscale catalysts; Nanoscale-dispersion; Powder samples; Room temperature; TEM analysis; Transmission electron; Activation energy; Catalysts; Desorption; Hydrides; Hydrogen; Hydrogen storage; Hydrogenation; Magnesium; Nanotechnology; Transmission electron microscopy; Vanadium; Chromium

A large group of asymptotic giant branch stars in the disk of M31: A missing piece of the puzzle? - Davidge, T.J. (The Astrophysical Journal Letters, 2012)
We examine the properties of a stellar grouping that is ∼3.5kpc to the northeast of the center of M31. This structure has (1) a surface brightness that is lower than the surrounding disk, (2) a more-or-less round appearance, (3) a size of ∼300 arcsec (∼1kpc), and (4) an integrated brightness K = 6.5. It is populated by stars with ages ≥100Myr and J - K colors that tend to be bluer than those of stars in the surrounding disk. Comparisons with model luminosity functions suggest that the star formation rate in this object has changed twice in the past few hundred Myr. Fitting a Sérsic function to the light profile reveals a power-law index and effective surface brightness that are similar to those of dwarf galaxies with the same integrated brightness. Two possible origins for this object are considered: (1) it is a heretofore undiscovered satellite of M31 that is seen against/in/through the M31 disk or (2) it is a fossil star-forming region in the M31 disk. © 2012. The American Astronomical Society. All rights reserved.

Electro-deposition and dissolution of MnO2 on a graphene composite electrode for its utilization in an aqueous based hybrid supercapacitor - Perret, P.G.; Malenfant, P.R.L.; Bock, C.; MacDougall, B. (Journal of the Electrochemical Society, 2012)
The electro-deposition and dissolution of MnO2 is studied for its potential utilization in hybrid supercapacitors. A commercially available graphene powder is used as high surface area substrate and capacitive type electrode. An aqueous electrolyte composed of 0.5 M H2SO4 + 0.5 M MnSO4 is used. The deposition-dissolution reaction of MnO2 is shown to provide the bulk of the charge storable in the battery type electrode. Furthermore, the potential window of stability of this electrode reaction is compatible with the aqueous electrolyte. Two complete systems were assembled and tested for their charge/discharge behavior. It is shown that energy and power densities of 25 Wh kg-1 and 980 W kg -1, respectively, can be achieved for at least 5000 cycles. Limitations of the system in terms of cycle numbers and electrolyte volume are discussed in more detail. The electrolyte volume to electrode mass ratio is shown to be a critical factor in determining the charge/discharge cycle number of the device. This is believed to be due to the fact that the efficiency of the MnO2 electro-dissolution/deposition process is less than 100%. This, in turn, could result in gradual pH changes and a lower Mn2+ concentration in the electrolyte during continues charging and discharging. This eventually results in lowering the energy and power density of the system. However, it is shown that an energy density of 25 Wh kg-1 is achievable, thus being comparable with similar hybrid systems. © 2012 The Electrochemical Society. All right reserved.
Keywords: Aqueous electrolyte; Charge/discharge cycle; Electrode reactions; Electrodissolution; Graphene composites; High surface area; Hybrid supercapacitors; Potential windows; Capacitors; Deposition; Dissolution; Electrolytes; Graphene; Hybrid systems; Manganese oxide

Comparison of spatial working memory in children with prenatal alcohol exposure and those diagnosed with ADHD; A functional magnetic resonance imaging study - Malisza, K.L.; Buss, J.L.; Bruce Bolster, R.; de Gervai, P.D.; Woods-Frohlich, L.; Summers, R.; Clancy, C.A.; Chudley, A.E.; Longstaffe, S. (Journal of Neurodevelopmental Disorders, 2012)
Background Alcohol related neurodevelopmental disorder (ARND) falls under the umbrella of fetal alcohol spectrum disorder (FASD), but individuals do not demonstrate the facial characteristics associated with fetal alcohol syndrome (FAS), making diagnosis difficult. While attentional problems in ARND are similar to those found in attentiondeficit/ hyperactivity disorder (ADHD), the underlying impairment in attention pathways may be different. Methods Functional magnetic resonance imaging (fMRI) of a working memory (1-back) task of 63 children, 10 to 14 years old, diagnosed with ARND and ADHD, as well as typically developing (TD) controls, was conducted at 3 T. Diffusion tensor imaging (DTI) data were also acquired. Results Activations were observed in posterior parietal and occipital regions in the TD group and in dorsolateral prefrontal and posterior parietal regions in the ARND group, whereas the ADHD group activated only dorsolateral prefrontal regions, during the working memory component of the task (1-back minus 0-back contrast). The increases in frontal and parietal activity were significantly greater in the ARND group compared to the other groups. This increased activity was associated with reduced accuracy and increased response time variability, suggesting that ARND subjects exert greater effort to manage short-term memory load. Significantly greater intra-subject variability, demonstrated by fMRI region-of-interest analysis, in the ADHD and ARND groups compared to the TD group suggests that momentto- moment lapses in attention contributed to their poorer task performance. Differences in functional activity in ARND subjects with and without a diagnosis of ADHD resulted primarily from reduced activation by the ARND/ADHD + group during the 0-back task. In contrast, children with ADHD alone clearly showed reduced activations during the 1-back task. DTI analysis revealed that the TD group had significantly higher total tract volume and number of fibers than the ARND group. These measures were negatively correlated with errors on the 1-back task, suggesting a link between white matter integrity and task performance. Conclusions fMRI activations suggest that the similar behavior of children with ARND and ADHD on a spatial working memory task is the result of different cognitive events. The nature of ADHD in children with ARND appears to differ from that of children with ADHD alone. © 2012 Malisza et al.
Keywords: atomoxetine; fluoxetine; olanzapine; quetiapine; risperidone; adolescent; alcohol related neurodevelopmental disorder; article; attention deficit disorder; child; comorbidity; conduct disorder; controlled study; depression; developmental disorder; diffusion tensor imaging; female; fetal alcohol syndrome; functional magnetic resonance imaging; human; learning disorder; major clinical study; male; neuropsychological test; occipital cortex; oppositional defiant disorder; posterior parietal cortex; prefrontal cortex; prenatal exposure; psychologic assessment; psychosocial disorder; school child; spatial memory; task performance; white matter; working memory

Trajectory learning for robot programming by demonstration using hidden markov model and dynamic time warping - Vakanski, A.; Mantegh, I.; Irish, A.; Janabi-Sharifi, F. (IEEE Transactions on Systems, Man, and Cybernetics, Part B: Cybernetics, 2012)
The main objective of this paper is to develop an efficient method for learning and reproduction of complex trajectories for robot programming by demonstration. Encoding of the demonstrated trajectories is performed with hidden Markov model, and generation of a generalized trajectory is achieved by using the concept of key points. Identification of the key points is based on significant changes in position and velocity in the demonstrated trajectories. The resulting sequences of trajectory key points are temporally aligned using the multidimensional dynamic time warping algorithm, and a generalized trajectory is obtained by smoothing spline interpolation of the clustered key points. The principal advantage of our proposed approach is utilization of the trajectory key points from all demonstrations for generation of a generalized trajectory. In addition, variability of the key points' clusters across the demonstrated set is employed for assigning weighting coefficients, resulting in a generalization procedure which accounts for the relevance of reproduction of different parts of the trajectories. The approach is verified experimentally for trajectories with two different levels of complexity. © 2012 IEEE.
Keywords: Complex trajectories; Dynamic time warping; Dynamic time warping algorithms; Keypoints; Programming by demonstration; Robot programming by demonstration; Smoothing spline; Weighting coefficient; Hidden Markov models; Programmable robots; Robot programming; Robotics; Trajectories

GPU-based visualization and synchronization of 4-D cardiac MR and ultrasound images - Zhang, Q.; Eagleson, R.; Peters, T.M. (IEEE Transactions on Information Technology in Biomedicine, 2012)
In minimally invasive image-guided interventions, different imaging modalities, such as magnetic resonance imaging (MRI), computed tomography (CT), and 3-D ultrasound (US), can provide complementary, multispectral image information. Dynamic image registration is a well-established approach that permits real-time diagnostic information to be enhanced by placing lower-quality real-time images within a high quality anatomical context. For the guidance of cardiac interventions, it would be valuable to register dynamic MRI or CT with intra-operative US. However, in practice, either the high computational cost prohibits such real-time visualization, or else the resulting image quality is not satisfactory for accurate interventional guidance. Modern graphics processing units (GPUs) provide the programmability, parallelism and increased computational precision to address this problem. In this paper, we first outline our research on dynamic 3-D cardiac MR and US image acquisition, real-time dual-modality registration and US tracking. Next, we describe our contributions on image processing and optimization techniques for 4-D (3-D + time) cardiac image rendering, and our GPU-accelerated methodologies for multimodality 4-D medical image visualization and optical blending, along with real-time synchronization of dual-modality dynamic cardiac images. Finally, multiple transfer functions, various image composition schemes, and an extended window-level setting and adjustment approach are proposed and applied to facilitate the dynamic volumetric MR and US cardiac data exploration and enhance the feature of interest of US image that is usually restricted to a narrow voxel intensity range. © 2012 IEEE.
Keywords: Cardiac imaging; Dynamic textures; extended window-level; GPU; Image compositing; Real time visualization; Blending; Computerized tomography; Heart; Image registration; Magnetic resonance imaging; Optical data processing; Program processors; Synchronization; Three dimensional computer graphics; Transfer functions; Ultrasonics; Visualization; Three dimensional; algorithm; article; computer graphics; computer simulation; factual database; four dimensional echocardiography; human; image processing; methodology; nuclear magnetic resonance imaging; Algorithms; Computer Graphics; Computer Simulation; Databases, Factual; Echocardiography, Four-Dimensional; Humans; Image Processing, Computer-Assisted; Magnetic Resonance Imaging, Cine

Electrochemical performance of carbon-supported co-phthalocyanine modified with co-added metals (M = Fe, Co, Ni, V) for oxygen reduction reaction - Ding, L.; Dai, X.; Lin, R.; Wang, H.; Qiao, J. (Journal of the Electrochemical Society, 2012)
Carbon-supported CoPc-M (where M = Fe, Co, Ni, V as the second active component) nanoparticle catalysts have been synthesized via a combined solvent-impregnation and milling procedure along with the high-temperature treatment. The effects of metal addition and metal loading on the electrocatalytic activity of carbon-supported CoPc were studied. Both heated and unheated catalysts were characterized by means of cyclic voltammetry (CV) and linear sweep voltammetry (LSV) employing a rotating disk electrode (RDE) in both acid and alkaline solutions to quantitatively obtain the oxygen reduction reaction (ORR) kinetic constants and the reaction mechanisms. The resulting CoPc-Fe/C of 40:60 ratio, heat-treated at 600°C, exhibited promising catalytic performance in terms of the ORR. The optimal loading of Fe was found to be 5 wt% when Fe loading was varied from 1 wt% to 8 wt% nominal. The transferred electron number, n, per oxygen molecule on CoPc-5%Fe/C electrode is in the range of 2.62-2.66 in acid solution and of 3.03-3.54 in alkaline solution compared to pure CoPc/C with the value of n in the range of 2.01-2.14 in acid solution and of 2.7-3.14 in alkaline solution, respectively. XRD, TEM and XPS analysis revealed that dispersion of the particle size of these carbon-supported catalysts is highly improved after modification of 5%Fe, thus the enhanced catalytic activities due to the increase in active centers which might be from the synergistic effect of Co-Nx and Fe-Nx. © 2012 The Electrochemical Society. All right reserved.
Keywords: Carbon-supported catalysts; Electrocatalytic activity; Electrochemical performance; Enhanced catalytic activity; High-temperature treatment; Oxygen reduction reaction; Oxygen reduction reaction kinetics; Rotating disk electrodes; Catalyst activity; Cyclic voltammetry; Electrolytic reduction; Nickel; Rate constants; Rotating disks; Synthesis (chemical); Carbon

AlGaN-free laser diodes by plasma-assisted molecular beam epitaxy - Skierbiszewski, C.; Siekacz, M.; Turski, H.; Muzioł, G.; Sawicka, M.; Feduniewicz-Zmuda, A.; Cywiński, G.; Cheze, C.; Grzanka, S.; Perlin, P.; Wiśniewski, P.; Wasilewski, Z.R.; et al. (Applied Physics Express, 2012)
Room-temperature continuous wave lasing at 432nm with a threshold current of 7.6 kA/cm2 for nitride-based laser diodes (LDs) grown by plasma-assisted molecular beam epitaxy is reported. The diodes were grown on c-plane GaN substrates with a threading dislocation density of 5 × 107 cm -2. We used a simplified laser structure design with GaN claddings where the optical modes were confined by the thick 120nm In 0:08Ga 0:92N waveguide. Our LDs show a high optical output power of 130mW, a differential gain of 0.5 W/A, and a lifetime of 50 h. © 2012 The Japan Society of Applied Physics.
Keywords: Continuous wave lasing; Differential gain; GaN substrate; Laser structures; Optical modes; Optical output power; Plasma-assisted molecular beam epitaxy; Room temperature; Threading dislocation densities; Threshold currents; Gallium nitride; Molecular beam epitaxy; Epitaxial growth

Physical simulations of seabed scouring by ice: Review and database - Barrette, P.; Sudom, D. (Proceedings of the International Offshore and Polar Engineering Conference, 2012)
This paper summarizes the compilation of information on physical simulations of seabed scouring by ice keels, and the resulting database. Physical simulations are critical for a proper understanding of ice scouring phenomena. A total of 487 scour simulations from twentyeight studies are reported. General information about test facility, soil, keel type, model pipeline, test conditions and results are outlined. The database can be used as a tool to identify knowledge gaps and guide future testing programs, to generate empirical relationships between the parameters involved during this interaction, or to validate numerical models. Copyright © 2012 by the International Society of Offshore and Polar Engineers (ISOPE).
Keywords: Empirical relationships; General information; Keel; Knowledge gaps; Physical simulation; Seabed; Simulation; Test condition; Testing programs; Database systems; Geologic models; Pipe; Pipelines; Scour; Ice

Deep-depletion Hamamatsu CCDs for the Gemini multi-object spectrograph - Hardy, T.; Hanna, K.; Szeto, K.; Burley, G. (High Energy, Optical, and Infrared Detectors for Astronomy V, 2012)
The instrumentation group of the Herzberg Institute of Astrophysics was commissioned by the Gemini Observatory to develop a new focal plane assembly for the Gemini Multi-Object Spectrograph with an array of three deep-depletion Hamamatsu CCDs. The main objective of the upgrade is to improve the sensitivity of the instrument in the red and nearinfrared wavelengths, with the additional benefits of reduced fringing, faster readout, and better performance in the "nod and shuffle" mode. We describe what we learned about these relatively new CCDs, including several problems encountered during testing, and report on the performance of the system. © 2012 SPIE.
Keywords: Deep-depletion; ESD; Focal plane assemblies; Hamamatsu; High-resistivity; Multi-object spectrograph; Near-infrared wavelength; Astrophysics; Charge coupled devices; Infrared detectors; Spectrographs

Brassica crop species : improving water use efficiency : challenges and opportunities - Palmer, Constantine Don; Keller, Wilf; Singh, Jas; Datla, Raju (Improving Crop Resistance to Abiotic Stress, 2012)
The Brassica species occupies a large portion of the world's economically important cultivated crops. These include vegetables, oilseeds, condiments, and forages. These crops are grown globally under a wide range of climatic conditions. With current concerns for food and energy security, expanded use of crop products, and environmental stewardship, there is a pressing need to improve yield through greater efficiency of resource utilization. Water availability is the most limiting factor to crop productivity and with the predicted scarcity, due to climate change and increased nonagricultural demand, improving water use efficiency (WUE) in crop production is an imperative. Consequently, increased carbon assimilation per unit of water used by Brassica crops must not only be realized but this carbon must also be efficiently partitioned into the harvested product. Thus, these plants need to be equipped with the genetic capacity to extract more water from the soil under water-limited conditions, fix more carbon, and transpire less water. There is natural genetic variability for WUE and this can be used for screening germplasm to identify better genotypes. Evaporative demand is the driving force for water loss and WUE can be improved by increasing transpiration efficiency (TE), alteration in crop phenology, increased carbon fixation, and increased harvest index (HI) by greater partitioning of assimilates into harvestable product. Modification of root architecture, leaf morphology, and stomata conductance are important targets for developing cultivars with improved WUE. Drought tolerance is closely associated with WUE and factors contributing to maintenance of metabolic function under water-limited conditions contribute to improved WUE. Studies on Arabidopsis have contributed to significant advances in our understanding of WUE and drought tolerance. The use of genetic engineering and genomic tools has allowed for the incorporation of identified genetic factors for improving WUE and drought tolerance traits and will be vital to the development of new Brassica cultivars. The carbon fixation machinery, a vital component in yield, will require adjustments to deal with anticipated water deficits in order to take advantage of increases in atmospheric carbon dioxide as a result of climate change. Manipulation of assimilate partitioning and selection of genotypes with capacity to store water-soluble carbohydrates in stems that can be remobilized to harvestable structures are targets for improving WUE. To maintain high yields of Brassica crops with economic use of water will require substantial increases in our understanding of the biological processes associated with growth under water-limited conditions. The availability of potential gene targets from the present and future discoveries including rapid advances coming from application of genomic technologies may provide a valuable resource base for development of superior WUE Brassica crops in the coming years.
Keywords: brassica; breeding; drought tolerance; transpiration efficiency; water use efficiency; yield

Crack growth behavior in ATI 718Plus® alloy - McDevitt, E.T.; Oppenheimer, S.M.; Kearsey, R.M.; Tsang, J. (Materials Science Forum, 2012)
ATI 718Plus® alloy is a new, cast and wrought, Ni-base superalloy with a maximum use temperature approximately 55°C higher than alloy 718. The mechanical properties have been well characterized by turbine engine OEM's and the alloy has been specified for use as static components and blades in gas turbine engines. Broader use of ATI 718Plus alloy in engine disk applications requires detailed understanding of the damage tolerance under creep and cyclic loading conditions. The results of a large testing program to evaluate the crack growth behavior of ATI 718Plus alloy at temperatures between 649°C and 704°C under conditions of fatigue, dwell-fatigue, and creep are presented. Crack growth rates in ATI 718Plus alloy in this temperature range are lower than alloy 718 and comparable to Waspaloy under non-dwell-fatigue conditions, and comparable to alloy 720 in dwell-fatigue tests. © 2012 Trans Tech Publications, Switzerland.
Keywords: Alloy 718; ATI 718Plus; Cast and wrought; Crack growth behavior; Creep crack growth; Cyclic loading conditions; Engine disk; Ni-base alloys; Ni-base superalloys; Temperature range; Testing programs; Turbine disks; Turbine engine; Waspaloy; Cracks; Creep; Fatigue crack propagation; Fatigue testing; Gas turbines; Growth (materials); Mechanical properties; Software testing; Superalloys; Testing; Turbomachine blades; Alloys; Crack propagation; Nickel; Cerium alloys

Theory of optical properties of II-VI semiconductor quantum dots containing a single magnetic ion in a strong magnetic field - Trojnar, A.H.; Korkusiński, M.; Potemski, M.; Hawrylak, P. (Physical Review B - Condensed Matter and Materials Physics, 2012)
We present a microscopic theory of the magnetic field dependence of the optical properties of II-VI semiconductor quantum dots containing a single magnetic (Mn) impurity. The single-particle electron and heavy-hole states are described exactly by two-dimensional harmonic oscillators in a magnetic field, the Mn ion is treated as a spin of an isoelectronic impurity, and the quantum dot anisotropy is included perturbatively. The electron-hole direct, short-, and long-range exchange electron-hole Coulomb interactions, as well as the short-range spin-spin contact exchange interaction of the electron and the hole with the magnetic impurity is included. The electron-hole-Mn states are expanded in a finite number of configurations controlled by the number of confined electronic quantum dot shells and the full interacting Hamiltonian is diagonalized numerically in this basis. The absorption and emission spectrum is predicted as a function of photon energy, magnetic field, number of confined shells, and anisotropy. It is shown that the magnetic-field-induced enhancement of the exchange interaction of the Mn spin with the exciton is largely canceled by increased electron-hole Coulomb interactions. The predicted weak magnetic field dependence of the spacing of emission lines agrees well with the results of the spin model at low magnetic fields but differs at higher magnetic fields. Correlations in the exciton-Mn complex are predicted to determine absorption spectra. © 2012 American Physical Society.

99 Herculis: Host to a circumbinary polar-ring debris disc - Kennedy, G.M.; Wyatt, M.C.; Sibthorpe, B.; Duchêne, G.; Kalas, P.; Matthews, B. C.; Greaves, J.S.; Su, K.Y.L.; Fitzgerald, M.P. (Monthly Notices of the Royal Astronomical Society, 2012)
We present resolved Herschel images of a circumbinary debris disc in the 99 Herculis system. The primary is a late F-type star. The binary orbit is well characterized and we conclude that the disc is misaligned with the binary plane. Two different models can explain the observed structure. The first model is a ring of polar orbits that move in a plane perpendicular to the binary pericentre direction. We favour this interpretation because it includes the effect of secular perturbations and the disc can survive for Gyr time-scales. The second model is a misaligned ring. Because there is an ambiguity in the orientation of the ring, which could be reflected in the sky plane, this ring either has near-polar orbits similar to the first model or has a 30° misalignment. The misaligned ring, interpreted as the result of a recent collision, is shown to be implausible from constraints on the collisional and dynamical evolution. Because disc+star systems with separations similar to 99 Herculis should form coplanar, possible formation scenarios involve either a close stellar encounter or binary exchange in the presence of circumstellar and/or circumbinary discs. Discovery and characterization of systems like 99 Herculis will help understand processes that result in planetary system misalignment around both single and multiple stars. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

A deep, wide-field, and panchromatic view of 47 Tuc and the SMC with HST: Observations and data analysis methods - Kalirai, J.S.; Richer, H.B.; Anderson, J.; Dotter, A.; Fahlman, G.G.; Hansen, B.M.S.; Hurley, J.; King, I.R.; Reitzel, D.; Rich, R.M.; Shara, M.M.; Stetson, P.B.; et al. (Astronomical Journal, 2012)
In Hubble Space Telescope (HST) Cycle 17, we imaged the well-known globular star cluster 47 Tucanae for 121 orbits using the Wide Field Channel of the Advanced Camera for Surveys (ACS) and both the UV/visible (UVIS) and IR channels of the newly installed Wide Field Camera 3 (WFC3) instrument (GO-11677, PI: H. Richer). This unique data set was obtained to address many scientific questions that demand a very deep, panchromatic, and panoramic view of the cluster's stellar populations. In total, the program obtained over 0.75Ms of imaging exposure time with the three HST cameras, over a time span of 9 months in 2010. The primary ACS field was imaged in the two broadband filters F606W and F814W, at 13 orientations, for all 121 orbits. The parallel WFC3 imaging provides a panchromatic (0.4-1.7 μm) and contiguous imaging swath over a 250° azimuthal range at impact radii of 6.5-17.9 pc in 47 Tuc. This imaging totals over 60 arcmin2 in area and utilizes the F390W and F606W broadband filters on WFC3/UVIS and the F110W and F160W broadband filters on WFC3/IR. In this paper, we describe the observational design of the new survey and one of the methods used to analyze all of the imaging data. This analysis combines over 700 full-frame images taken with the three HST cameras into a handful of ultra-deep, well-sampled combined images in each of the six filters. We discuss in detail the methods used to calculate accurate transformations that provide optimal alignment of the input images, the methods used to perform sky background offsets in the input stack and the flagging of deviant pixels, and the balance reached between the input-pixel drop size onto an output supersampled pixel grid. Careful photometric, morphological, and astrometric measurements are performed on the stacks using iterative PSF-fitting techniques, and reveal unprecedented color-magnitude diagrams of the cluster extending to >30th magnitude in the optical, 29th magnitude in the UV, and 27th magnitude in the IR. The data set provides a characterization of the complete stellar populations of 47 Tuc, extending from the faintest hydrogen-burning dwarfs through the main-sequence and giant branches down to very cool white dwarf remnants in the cluster. The imaging also provides the deepest probe of the stellar populations of the background Small Magellanic Cloud galaxy, resolving low-mass main-sequence dwarfs with M ≲ 0.2 M ⊙.

VLBI for Gravity Probe B. III. A limit on the proper motion of the "core" of the quasar 3C454.3 - Bartel, N.; Bietenholz, M.F.; Lebach, D.E.; Lederman, J.I.; Petrov, L.; Ransom, R.R.; Ratner, M.I.; Shapiro, I.I. (Astrophysical Journal, Supplement Series, 2012)
We made very long baseline interferometry observations at 8.4GHz between 1997 and 2005 to estimate the coordinates of the "core" component of the superluminal quasar, 3C454.3, the ultimate reference point in the distant universe for the NASA/Stanford Gyroscope Relativity Mission, Gravity Probe B (GP-B). These coordinates are determined relative to those of the brightness peaks of two other compact extragalactic sources, B2250+194 and B2252+172, nearby on the sky, and within a celestial reference frame (CRF), defined by a large suite of compact extragalactic radio sources, and nearly identical to the International Celestial Reference Frame 2 (ICRF2). We find that B2250+194 and B2252+172 are stationary relative to each other, and also in the CRF, to within 1σ upper limits of 15 and 30 μasyr -1 in α and δ, respectively. The core of 3C454.3 appears to jitter in its position along the jet direction over 0.2mas, likely due to activity close to the putative supermassive black hole nearby, but on average is stationary in the CRF within 1σ upper limits on its proper motion of 39 μasyr -1 (1.0c) and 30 μasyr -1 (0.8c) in α and δ, respectively, for the period 2002-2005. Our corresponding limit over the longer interval, 1998-2005, of more importance to GP-B, is 46 and 56 μasyr -1 in α and δ, respectively. Some of 3C454.3's jet components show significantly superluminal motion with speeds of up to 200 μasyr -1 or 5c in the CRF. The core of 3C454.3 thus provides for GP-B a sufficiently stable reference in the distant universe. © 2012. The American Astronomical Society. All rights reserved..

Lipid-sensing high-throughput ApoA-I assays - Niedziela-Majka, A.; Lad, L.; Chisholm, J.W.; Lagpacan, L.; Schwartz, K.; Hung, M.; Jin, D.; Fung, W.; Brendza, K.M.; Liu, X.; Pagratis, N.; Sakowicz, R. (Journal of Biomolecular Screening, 2012)
Apolipoprotein A-I (ApoA-I), a primary protein component of high-density lipoprotein (HDL), plays an important role in cholesterol metabolism mediating the formation of HDL and the efflux of cellular cholesterol from macrophage foam cells in arterial walls. Lipidation of ApoA-I is mediated by adenosine triphosphate (ATP) binding cassette A1 (ABCA1). Insufficient ABCA1 activity may lead to increased risk of atherosclerosis due to reduced HDL formation and cholesterol efflux. The standard radioactive assay for measuring cholesterol transport to ApoA-I has low throughput and poor dynamic range, and it fails to measure phospholipid transfer. We describe the development of two sensitive, nonradioactive high-throughput assays that report on the lipidation of ApoA-I: a homogeneous assay based on time-resolved fluorescence resonance energy transfer (TR-FRET) and a discontinuous assay that uses the label-free Epic platform. The TR-FRET assay employs HiLyte Fluor 647-labeled ApoA-I with N-terminal biotin bound to streptavidin-terbium. When fluorescent ApoA-I was incorporated into HDL, TR-FRET decreased proportionally to the increase in the ratio of lipids to ApoA-I, demonstrating that the assay was sensitive to the amount of lipid bound to ApoA-I. In the Epic assay, biotinylated ApoA-I was captured on a streptavidin-coated biosensor. Measured resonant wavelength shift was proportional to the amount of lipids associated with ApoA-I, indicating that the assay senses ApoA-I lipidation. © 2012 Society for Laboratory Automation and Screening.
Keywords: ABC transporter A1; apolipoprotein A1; biotin; high density lipoprotein cholesterol; lipid; streptavidin; terbium; amino terminal sequence; artery wall; article; atherosclerosis; biotinylation; cholesterol metabolism; cholesterol transport; controlled study; fluorescence resonance energy transfer; foam cell; high throughput screening; human; human cell; lipid analysis; phospholipid transfer; priority journal; protein determination; radioactivity; risk assessment; Apolipoprotein A-I; Atherosclerosis; ATP-Binding Cassette Transporters; Biotin; Cells, Cultured; Cholesterol; Fluorescence Resonance Energy Transfer; Fluorescent Dyes; High-Throughput Screening Assays; Humans; Lipid Metabolism; Lipids; Lipoproteins, HDL; Macrophages; Streptavidin

Motor protein Myo5p is required to maintain the regulatory circuit controlling WOR1 expression in Candida albicans - Kachurina, N.; Turcotte, B.; Whiteway, M. (Eukaryotic Cell, 2012)
The Candida albicans MYO5 gene encodes myosin I, a protein required for the formation of germ tubes and true hyphae. Because the polarized growth of opaque-phase cells in response to pheromone results in mating projections that can resemble germ tubes, we examined the role of Myo5p in this process. We localized green fluorescent protein (GFP)-tagged Myo5p in opaquephase cells of C. albicans during both bud and shmoo formation. In vegetatively growing opaque cells, Myo5p is found at sites of bud emergence and bud growth, while in pheromone-stimulated cells, Myo5p localizes at the growing tips of shmoos. Intriguingly, cells homozygous for MTLa in which the MYO5 gene was deleted failed to switch efficiently from the white phase to the opaque phase, although ectopic expression of WOR1 from the MET3 promoter can convert myo5 mutants into mating-competent opaque cells. However, when WOR1 expression was shut off, the myo5-defective cells rapidly lost both their opaque phenotype and mating competence, suggesting that Myo5p is involved in the maintenance of the opaque state. When MYO5 is expressed conditionally in opaque cells, the opaque phenotype, as well as the mating ability of the cells, becomes unstable under repressive conditions, and quantitative real-time PCR demonstrated that the shutoff of MYO5 expression correlates with a dramatic reduction in WOR1 expression. It appears that while myosin I is not directly required for mating in C. albicans, it is involved in WOR1 expression and the white-opaque transition and thus is indirectly implicated in mating. © 2012, American Society for Microbiology. All Rights Reserved.
Keywords: fungal protein; green fluorescent protein; myosin I; transcription factor; allele; article; Candida albicans; culture medium; fungal gene; gene expression regulation; gene inactivation; gene regulatory network; genetic transcription; genetics; metabolism; phenotype; physiology; promoter region; real time polymerase chain reaction; regulator gene; Alleles; Candida albicans; Culture Media; Fungal Proteins; Gene Expression Regulation, Fungal; Gene Knockout Techniques; Gene Regulatory Networks; Genes, Mating Type, Fungal; Genes, Switch; Green Fluorescent Proteins; Myosin Type I; Phenotype; Promoter Regions, Genetic; Real-Time Polymerase Chain Reaction; Transcription Factors; Transcription, Genetic; Candida albicans

The Next Generation Virgo Cluster Survey (NGVS). I. Introduction to the survey - Ferrarese, L.; Côté, P.; Cuillandre, J.-C.; Gwyn, S.D.J.; Peng, E.W.; MacArthur, L.A.; Duc, P.-A.; Boselli, A.; Mei, S.; Erben, T.; McConnachie, A.W.; Durrell, P.R.; et al. (Astrophysical Journal, Supplement Series, 2012)
The Next Generation Virgo Cluster Survey (NGVS) is a program that uses the 1 deg 2 MegaCam instrument on the Canada-France-Hawaii Telescope to carry out a comprehensive optical imaging survey of the Virgo cluster, from its core to its virial radius - covering a total area of 104 deg 2 - in the u*griz bandpasses. Thanks to a dedicated data acquisition strategy and processing pipeline, the NGVS reaches a point-source depth of g 25.9 mag (10σ) and a surface brightness limit of μ g 29 mag arcsec -2 (2σ above the mean sky level), thus superseding all previous optical studies of this benchmark galaxy cluster. In this paper, we give an overview of the technical aspects of the survey, such as areal coverage, field placement, choice of filters, limiting magnitudes, observing strategies, data processing and calibration pipelines, survey timeline, and data products. We also describe the primary scientific topics of the NGVS, which include: the galaxy luminosity and mass functions; the color-magnitude relation; galaxy scaling relations; compact stellar systems; galactic nuclei; the extragalactic distance scale; the large-scale environment of the cluster and its relationship to the Local Supercluster; diffuse light and the intracluster medium; galaxy interactions and evolutionary processes; and extragalactic star clusters. In addition, we describe a number of ancillary programs dealing with "foreground" and "background" science topics, including the study of high-inclination trans-Neptunian objects; the structure of the Galactic halo in the direction of the Virgo Overdensity and Sagittarius Stream; the measurement of cosmic shear, galaxy-galaxy, and cluster lensing; and the identification of distant galaxy clusters, and strong-lensing events. © 2012. The American Astronomical Society. All rights reserved..

Fuel property effects on PCCI combustion in a heavy-duty diesel engine - Dumitrescu, C.E.; Stuart Neill, W.; Guo, H.; Hosseini, V.; Chippior, W.L. (Journal of Engineering for Gas Turbines and Power, 2012)
An experimental study was performed to investigate fuel property effects on premixed charge compression ignition (PCCI) combustion in a heavy-duty diesel engine. A matrix of research diesel fuels designed by the Coordinating Research Council, referred to as the Fuels for Advanced Combustion Engines (FACE), was used. The fuel matrix design covers a wide range of cetane numbers (30 to 55), 90% distillation temperatures (270 to 340° C) and aromatics content (20 to 45%). The fuels were tested in a single-cylinder Caterpillar diesel engine equipped with a common-rail fuel injection system. The engine was operated at 900 rpm, a relative air/fuel ratio of 1.2 and 60% exhaust gas recirculation (EGR) for all fuels. The study was limited to a single fuel injection event starting between -30° and 0° CA after top dead center (aTDC) with a rail pressure of 150 MPa. The brake mean effective pressure (BMEP) ranged from 2.6 to 3.1 bar depending on the fuel and its injection timing. The experimental results show that cetane number was the most important fuel property affecting PCCI combustion behavior. The low cetane number fuels had better brake specific fuel consumption (BSFC) due to more optimized combustion phasing and shorter combustion duration. They also had a longer ignition delay period available for premixing, which led to near-zero soot emissions. The two fuels with high cetane number and high 90 distillation temperature produced significant soot emissions. The two fuels with high cetane number and high aromatics produced the highest brake specific NO x emissions, although the absolute values were below 0.1 g/kW-h. Brake specific HC and CO emissions were primarily a function of the combustion phasing, but the low cetane number fuels had slightly higher HC and lower CO emissions than the high cetane number fuels. © 2012 American Society of Mechanical Engineers.
Keywords: Absolute values; Air/fuel ratio; Brake mean effective pressures; Brake specific fuel consumption; CO emissions; Combustion duration; Combustion engines; Combustion phasing; Common rail; Distillation temperature; experimental; Experimental studies; Fuel injection systems; Fuel matrix; Fuel properties; Heavy-duty diesel engine; Ignition delays; Injection timing; matrix; PCCI combustion; Premixed charge compression ignition; Premixing; Rail pressures; Soot emissions; Top dead center; Antiknock rating; Brakes; Design; Diesel engines; Diesel fuels; Distillation; Fuel injection; Ignition; Internal combustion engines; Soot; Fuels

Dyson norms in XUV and strong-field ionization of polyatomics: Cytosine and uracil - Spanner, M.; Patchkovskii, S.; Zhou, C.; Matsika, S.; Kotur, M.; Weinacht, T.C. (Physical Review A - Atomic, Molecular, and Optical Physics, 2012)
The extreme-ultraviolet (XUV) and strong-field valence ionization of cytosine and uracil is considered. We examine some simple estimates of the relative yields of the cation states populated following ionization and compare these to the results of a recently developed ab initio-type numerical model designed to compute strong-field ionization of molecules, the so-called time-dependent resolution in ionic states (TD-RIS) method. In analogy with one-photon XUV ionization, where the photoionization matrix elements can be related to the Dyson orbitals, we construct estimates for the yield of strong-field ionization (SFI) to different cation states based on the Dyson orbital norms and the Keldysh tunneling ionization rate. In the case of XUV ionization, the Dyson norms are shown to be good predictors of the relative cation yields when compared with the TD-RIS yields. The Dyson- and Keldysh-based models underestimate the yield to excited cation states in the case of SFI. The increased yield to the excited cation states in the TD-RIS results is attributed to the inclusion of multielectron effects and continuum structure not present in the simple models. The molecular Ammosov-Delone-Krainov (MO-ADK) method of calculating SFI is also considered. This later method is seen to agree more closely with the Dyson- and Keldysh-based estimates as it also fails to capture the multielectron effects and continuum structure included in the TD-RIS approach. ©2012 American Physical Society.
Keywords: Ammosov-Delone-Krainov; Continuum structures; Dyson orbital; Extreme ultraviolets; Ionic state; Matrix elements; Multi-electron; Polyatomics; Strong field ionization; Time-dependent; Tunneling ionization; Valence ionization; Aromatic compounds; Estimation; Interlocking signals; Positive ions; Photoionization

The structure of the extracellular teichoic acids from the allergy-protective bacterium Lactococcus lactis G121 - Fischer, K.; Vinogradov, E.; Lindner, B.; Heine, H.; Holst, O. (Biological Chemistry, 2012)
The Gram-positive bacterium Lactococcus lactis G121 is a farm isolate that protects mice from ovalbumin-induced asthma. To understand the molecular mechanisms of such allergy-protective properties, the isolation and characterization of cell envelope constituents is crucial. Here, structural analyses of the extracellular teichoic acid (EC TA) from L. lactis G121 are presented. Extraction with 0.9 % saline afforded a crude TA fraction. Consecutive size exclusion chromatography on Biogel P60 and P10 matrix was performed to purify the sample. Chemical component analyses, high-resolution electrospray ionization Fourier-transformed ion cyclotron mass spectrometry, and nuclear magnetic resonance spectroscopy were conducted for structural elucidation. The EC TA was a poly(glycosylglycerol phosphate) molecule with a repeating unit of -6)-[β- d-Glcp -(1→3)-][α- d-Glcp NAc-(1→4)-]α- d-Galp NAc-(1→3)-β-d-Glcp NAc-(1→2)-glycerol-(1- P -). Copyright © by Walter de Gruyter • Berlin • Boston.
Keywords: antiallergic agent; extracellular teichoic acid; sodium chloride; teichoic acid; unclassified drug; allergic asthma; article; chemical structure; controlled study; electrospray mass spectrometry; extraction; gel permeation chromatography; ion cyclotron resonance mass spectrometry; Lactococcus lactis; nonhuman; priority journal; proton nuclear magnetic resonance; Animals; Carbohydrate Sequence; Hypersensitivity; Lactococcus lactis; Mice; Molecular Sequence Data; Nuclear Magnetic Resonance, Biomolecular; Spectrometry, Mass, Electrospray Ionization; Teichoic Acids

Development of a tissue-mimicking neck model for medical education - Xu, J.J.; Fung, K.; Glicksman, J.D.; Brandt, M.G.; Campbell, G. (Journal of Otolaryngology - Head and Neck Surgery, 2012)
Background: The ability to palpate neck masses and lymph nodes and appreciate qualities such as size, location, and consistency is critical for patient care and an important clinical skill for all physicians. Medical students currently learn neck palpation by practicing on healthy, standardized patients; however, studies of similar procedures have shown that educational models with simulated pathology help improve technique and confidence. Objective: Our goal was to create a tissue-mimicking neck model with palpable masses. Methods: Iterative design and development of a high-fidelity neck model using polyvinyl alcohol-cryogel (PVA-C), a nontoxic and biocompatible polymer that exhibits favourable tissue-mimicking elastic properties. Model geometries were digitally reconstructed from high-resolution cadaveric magnetic resonance imaging sections to create physical moulds through stereolithography. PVA-C was formulated to mimic the characteristics of human tissue. Results: A life-like neckmodelwas built and consists of these components: muscle, larynx, spine, soft tissue, pathologic nodes, and skin. Discussion: A final neck model prototype has been completed and will be evaluated by otolaryngology consultants and residents for face and construct validity and assessed in a randomized, controlled trial to evaluate how it impacts students' ability to detect neck masses. © 2012 The Canadian Society of Otolaryngology-Head & Neck Surgery.
Keywords: polyvinyl alcohol; article; cryogel; elasticity; geometry; image reconstruction; lymph node; medical education; neck; neck tumor; nuclear magnetic resonance imaging; palpation; priority journal; simulation; stereolithography; Education, Medical; Head and Neck Neoplasms; Humans; Imaging, Three-Dimensional; Lymph Nodes; Magnetic Resonance Imaging; Models, Anatomic; Neck; Palpation; Reproducibility of Results; Tomography, X-Ray Computed

Athermal silicon waveguides with bridged subwavelength gratings for TE and TM polarizations - Ibrahim, Marc; Schmid, Jens H.; Aleali, Alireza; Cheben, Pavel; Lapointe, Jean; Janz, Siegfried; Bock, Przemek J.; Densmore, Adam; Lamontagne, Boris; Ma, Rubin; Xu, Dan-Xia; Ye, Winnie N. (Optics Express, 2012)
In this paper, athermal silicon waveguides using bridged subwavelength grating (BSWG) structures are proposed and investigated. The realization of temperature-independent BSWG waveguides for both polarizations is demonstrated numerically and experimentally. SU-8 polymer is used as the cladding material to compensate for the positive thermo-optic (TO) coefficient (dn/dT) of silicon. We investigate the dependence of the effective TO coefficient of BSWG waveguides on both the bridge width and grating duty cycle. The BSWG waveguides have a width of 490 nm, a height of 260 nm, and a grating pitch of 250 nm. Athermal behavior is achieved for both the transverse-magnetic (TM) and the transverse-electric (TE) polarized light for a variety of bridge width and duty cycle combinations. Furthermore, the BSWGs can be designed to be athermal for both TE and TM polarization simultaneously. © 2012 Optical Society of America.
Keywords: Cladding material; Duty cycles; Grating pitch; Silicon waveguide; SU-8 polymer; Sub-wave length grating; Thermooptic coefficients; TM polarization; Cladding (coating); Polarization; Waveguides

Temperature-independent silicon waveguides comprising bridged subwavelength gratings - Ibrahim, M.; Aleali, A.; Schmid, J.H.; Cheben, P.; Lapointe, J.; Janz, S.; Bock, P.J.; Densmore, A.; Lamontagne, B.; Ma, R.; Xu, D.-X.; Ye, W.N. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Athermal operation of silicon waveguides for the TM and TE mode is achieved using the bridged subwavelength grating (BSWG) waveguide geometry. For the TM mode the experimental results show that the temperature-induced wavelength shift (dλ/dT) is an order of magnitude smaller for the BSWG waveguides with grating duty cycle, waveguide and bridge widths of 42%, 490 nm and 220 nm, respectively, as compared to standard photonics wires (PW). For the TE mode similar results are achieved by using the bridge width of 200 nm and similar duty cycle and waveguide width. A temperature-induced shift of only -2.5 pm/°C is reported for the TM polarized light. Propagation losses of BSWG waveguides for both polarizations were measured to be about 8 dB/cm, comparable to that of PWs. © 2012 SPIE.
Keywords: Athermal; Grating duty cycle; Silicon photonics; Sub-wave length grating; Thermo-optic coefficients; Electric losses; Photonics; Silicon; Waveguides

Silicon and silicon oxide surface modification using thiamine-catalyzed benzoin condensations - Hoop, K.A.; Kennedy, D.C.; Mishki, T.; Lopinski, G.P.; Pezacki, J.P. (Canadian Journal of Chemistry, 2012)
The benzoin condensation that involves the umpolung coupling of two aldehyde groups has been applied to the formation of functionalized silicon and silicon oxide surfaces using thiamine and other N-heterocyclic carbene (NHC) catalysis in water. This bioorthogonal conjugation of an aldehyde to a modified silicon or silicon oxide surface has been monitored and characterized using X-ray photoelectron spectroscopy and IR spectroscopy. NHC catalysis was found to be efficient in water mediating full conversion of the aldehyde functionalized silicon oxide surfaces at the interface. © 2012 Published by NRC Research Press.
Keywords: Benzoin condensation; Catalysis in water; Functionalized; N-heterocyclic carbenes; Silicon oxide surfaces; Surface functionalization; Umpolung; Aldehydes; Catalysis; Condensation; Functional groups; Silicon; Silicon compounds; X ray photoelectron spectroscopy; Silicon oxides

Persistence and eventual demise of oxygen molecules at terapascal pressures - Sun, J.; Martinez-Canales, M.; Klug, D.D.; Pickard, C.J.; Needs, R.J. (Physical Review Letters, 2012)
Computational searches for structures of solid oxygen under high pressures in the multi-TPa range are carried out using density-functional-theory methods. We find that molecular oxygen persists to about 1.9 TPa at which it transforms into a semiconducting square-spiral-like polymeric structure (I4 1/acd) with a band gap of ∼3.0eV. Solid oxygen forms a metallic zigzag chainlike structure (Cmcm) at about 3.0 TPa, but the chains in each layer gradually merge as the pressure is increased and a structure of Fmmm symmetry forms at about 9.3 TPa in which each atom has four nearest neighbors. The superconducting properties of molecular oxygen do not vary much with compression, although the structure becomes more symmetric. The electronic properties of oxygen have a complex evolution with pressure, swapping between insulating, semiconducting, and metallic. © 2012 American Physical Society.
Keywords: Chainlike structure; Complex evolutions; High pressure; Nearest neighbors; Oxygen molecule; Polymeric structures; Solid oxygen; Superconducting properties; Density functional theory; Electronic properties; Molecular oxygen

Solid state spectroelectrochemistry of redox reactions in polypyrrole/oxide molecular heterojunctions - Bonifas, A.P.; McCreery, R.L. (Analytical Chemistry, 2012)
To understand the mechanism of bias-induced resistance switching observed in polypyrrole (PPy) based solid state junctions, in situ UV-vis absorption spectroscopy was employed to monitor oxidation states within PPy layers in solution and in PPy/metal oxide junctions. For PPy layers in acetonitrile, oxidation led primarily to cationic polaron formation, while oxidation in 0.1 M NaOH in H 2O resulted in imine formation, caused by deprotonation of polarons. On the basis of these results in solution, spectroelectrochemistry was used to monitor bias-induced formation of polarons and imines in PPy layers incorporated into solid state carbon/PPy/Al 2O 3/Pt junctions. A positive bias on the carbon electrode caused PPy oxidation, with the formation of polaron and imine species strongly dependent on the surrounding environment. The spectral changes associated with polarons or imines were stable for at least several hours after the applied bias, while a negative bias reversed the absorbance changes back to the initial PPy spectrum. These results indicate that PPy can be oxidized in nominally solid state devices, and the formation of stable polarons is dependent on the tendency for deprotonation of the polaron to the imine. Since PPy conductivity depends strongly on the polaron concentration, monitoring its concentration is critical to determining resistance switching mechanisms. Furthermore, the importance of ion mobility and OH - generation through H 2O reduction at the Pt contact are discussed. © 2012 American Chemical Society.
Keywords: Absorbance change; Applied bias; Carbon electrode; Imine formation; In-situ; Ion Mobility; Negative bias; Oxidation state; Oxide junction; Polaron formation; Polypyrrole (PPy); Positive bias; Resistance switching; Solid-state carbon; Spectral change; Surrounding environment; Acetonitrile; Electric resistance; Heterojunctions; Nitrogen compounds; Oxidation; Platinum; Polypyrroles; Redox reactions; Solid state devices; Spectroelectrochemistry; Ultraviolet spectroscopy; Polarons

A measurement system with contour tracking for repair of components - Li, Y.; Xue, L. (International Journal of Manufacturing Research, 2012)
The repair of worn-out components requires the extraction of their actual geometry. To acquire the surface contour, a laser displacement sensor and a CNC motion system are typically used. One of the factors that affect the measuring accuracy is the sensor's resolution. A high resolution sensor usually has a short measuring range. Therefore, a contour with a large peak-to-valley height cannot usually be measured using a short range sensor. In this research, a measurement system of tracking target surface was developed. The proposed measurement system has been used for repair of worn-out components using laser cladding. Copyright © 2012 Inderscience Enterprises Ltd.
Keywords: Contour tracking; Displacement sensor; High resolution sensors; Laser displacement sensors; Measurement system; Measuring accuracy; Motion system; Range sensors; Surface contour; Target surface; Contour measurement; Laser cladding; Measurements; Repair; Sensors; Displacement measurement

Insights into semiconductor nanowire conductivity using electrodeposition - Liu, C.; Salehzadeh, O.; Poole, P.J.; Watkins, S.P.; Kavanagh, K.L. (Semiconductor Science and Technology, 2012)
Copper (Cu) and iron (Fe) electrical contacts to gallium arsenide (GaAs) and indium arsenide (InAs) nanowires (NWs) have been fabricated via electrodeposition. For undoped or low carbon-doped (10 17/cm 3), p-type GaAs NWs, Cu or Fe nucleate and grow only on the gold catalyst at the NW tip, avoiding the sidewalls. Metal growth is limited by the Au contact resistance due to thick sidewall depletion layers. For InAs NWs and heavier-doped, core-shell (undoped core-C-doped shell) GaAs NWs, metal nucleation and growth occurs on the sidewalls as well as on the gold catalyst limited now by the ion electrolyte diffusivity. © 2012 IOP Publishing Ltd.
Keywords: Core-shell; Depletion layer; Electrical contacts; GaAs; Gold catalysts; InAs; Metal growth; Nucleation and growth; P-type GaAs; Semiconductor nanowire; Catalysts; Electrodeposition; Gold; Indium arsenide; Nanowires; Semiconducting gallium; Gallium arsenide

Microindentation creep of secondary hydrated cement phases and C-S-H - Nguyen, D.-T.; Alizadeh, R.; Beaudoin, J.J.; Raki, L. (Materials and Structures/Materiaux et Constructions, 2012)
Microindentation creep measurements were obtained on compacted specimens of several secondary hydrated cement phases in equilibrium with water vapor at 11%RH. Values of creep modulus, indentation modulus and indentation hardness for calcium hydroxide, ettringite, gypsum and calcium carbonate are reported. The porosity dependence of these parameters was established and the significance of porosity on the time-dependent deformation of these materials was discussed. In addition the microindentation creep behavior of pure C-S-H and C3S paste hydrated 32 years was determined. The discussion focuses on the relative importance of the contribution of the secondary phases in hydrated cement-based materials to creep with respect to the more 'active' C-S-H phase. © 2012 RILEM.

The multielectron ionization dynamics underlying attosecond strong-field spectroscopies - Boguslavskiy, A.E.; Mikosch, J.; Gijsbertsen, A.; Spanner, M.; Patchkovskii, S.; Gador, N.; Vrakking, M.J.J.; Stolow, A. (Science, 2012)
Subcycle strong-field ionization (SFI) underlies many emerging spectroscopic probes of atomic or molecular attosecond electronic dynamics. Extending methods such as attosecond high harmonic generation spectroscopy to complex polyatomic molecules requires an understanding of multielectronic excitations, already hinted at by theoretical modeling of experiments on atoms, diatomics, and triatomics. Here, we present a direct method which, independent of theory, experimentally probes the participation of multiple electronic continua in the SFI dynamics of polyatomic molecules. We use saturated (n-butane) and unsaturated (1,3-butadiene) linear hydrocarbons to show how subcycle SFI of polyatomics can be directly resolved into its distinct electronic-continuum channels by above-threshold ionization photoelectron spectroscopy. Our approach makes use of photoelectron-photofragment coincidences, suiting broad classes of polyatomic molecules.
Keywords: hydrocarbon; electron; hydrocarbon; ionization; spectroscopy; timescale; absorption; absorption spectroscopy; article; chemical structure; electron; geometry; ionization; laser; multielectron ionization dynamics; photon; priority journal; spectroscopy

Nickel nanoparticles synthesized by a modified polyol method for the purification of histidine-tagged single-domain antibody ToxA5.1 - Parisien, A.; Al-Zarka, F.; Hussack, G.; Baranova, E.A.; Thibault, J.; Qingdao Lan, C. (Journal of Materials Research, 2012)
Nickel nanoparticles (NNPs) synthesized by a modified polyol method using ethylene glycol as a reducing agent, palladium chloride as a nucleating agent, and polyvinylpyrrolidone (PVP) as a protective agent were investigated as a potential magnetic adsorbent for the purification of hexahistidine-tagged (His6-tagged) recombinant proteins. The synthesis resulted in nanoparticles having an average diameter of 6828 nm. The x-ray diffraction pattern confirmed the presence of nickel metal, as well as the presence of unreacted nickel (II) hydroxide Ni(OH)2. Magnetic characterization showed that a magnetization saturation of 39.3 electromagnetic unit (emu)/g at 20,000 Oersted (Oe) was reached rapidly and that the material exhibited ferromagnetic behavior. Protein purification results showed that the synthesized NNPs were highly selective for binding to a His6-tagged recombinant protein single-domain antibody ToxA5.1. In addition, NNPs were used for four adsorption cycles without significant binding capacity losses. These particles have shown great potential such as being easily synthesized, cost-effective, and highly selective magnetic adsorbents for the purification of His6-tagged recombinant proteins. © Copyright © Materials Research Society 2012.
Keywords: Adsorption cycle; Average diameter; Binding capacities; Ferromagnetic behaviors; magnetic; Magnetic adsorbents; Magnetic characterization; Magnetization-saturation; Modified polyol method; Nickel nanoparticles; Nucleating agents; Palladium chloride; Polyvinyl pyrrolidone; Protective agents; Protein purification; Single domains; Adsorbents; Adsorption; Alcohols; Amino acids; Antibodies; Chlorine compounds; Ethylene glycol; Magnetic domains; Nanomagnetics; Nanoparticles; Nickel; Nickel compounds; Palladium; Purification; Recombinant proteins; Saturation magnetization; X ray diffraction; Biosynthesis

Debris discs at centimetre wavelengths: Planetesimal populations in young extrasolar Kuiper belts - Greaves, J.S.; Hales, A.S.; Mason, B.S.; Matthews, B.C. (Monthly Notices of the Royal Astronomical Society: Letters, 2012)
Two luminous debris discs around 100 Myr old have been searched for 1 cm dust emission, to a depth three times greater than in any such previous study. Very low limits were set towards both HD 377 and HD 104860 (noise levels of 12-14 μJy), extending the spectral range from 70 μm to 3mm where cool dust has previously been sought. The almost-identical fluxes of the two systems were merged into an average spectral energy distribution, which was then fitted using a distribution of grain sizes. The canonical infinite collisional cascade, with numbers of particles n(D)∝D -3.5 for diameter D, overpredicts the 1-cm flux, which should have been detected at over 3σ for the merged system. Preferred solutions have truncated grain populations with largest particles around 1.5-4mm in diameter, and slightly flatter distributions, up to n(D)∝D -3.1. The lack of cm-sized and larger particles is reminiscent of the similar deficit inferred around comets from spacecraft encounters. Such departures from simple power-law distributions of particles have been predicted in recent models where some size regimes are more readily broken up than others. A deficit of cm-scale particles can explain the fits we obtain, and reduces the total masses inferred for the comet belts of these stars. © 2012 The Authors. Monthly Notices of the Royal Astronomical Society. © 2012 RAS.

Single-walled carbon nanotube-modified epoxy thin films for continuous crack monitoring of metallic structures - Ashrafi, B.; Johnson, L.; Martinez-Rubi, Y.; Martinez, M.; Mrad, N. (Structural Health Monitoring, 2012)
Cracks are one of the primary forms of damage that can lead to the catastrophic failure of metallic structures. This study focuses on the application of epoxy nanocomposite thin film sensors for continuous monitoring of crack evolution in metallic structures. The core approach was to monitor the current (or resistance) change in these nanocomposite films, as cracks develop and propagate in the metallic host structure. Based on optical, electrical, and mechanical properties of epoxy resins modified with different contents of single-walled carbon nanotubes, two different nanocomposites (with 0.3 and 1.0 wt%) were chosen for the development of a crack sensor. The performance of the nanocomposite sensors was evaluated under tension-tension fatigue tests, on aluminum coupons with centrally located through thickness electrical discharge machining notches. Crack growth in the aluminum was found to transfer to the nanocomposite films in a stable mode. Once the crack was established, a linear correlation was found between the measured current and crack length with a slope of -10 -11 and -10 -8 A/mm for 0.3 and 1.0 wt% nanocomposites, respectively. Contact between the asperities formed on the crack surfaces in the nanocomposite film while the crack was closed at small loads (<30% of maximum load) was found to be an important limiting factor causing a large variation in measured currents during each fatigue cycle. Hence, a normalized variable based upon current change during each cycle was defined, providing a more accurate measurement of the crack size, with a crack gauge factor of ~0.04 mm -1. In summary, the nanocomposite thin film sensor developed in this study offers both continuous crack growth monitoring and the possibility of strain sensing. The sensor is also suitable for visual inspection of the host structure due to the transparency of the developed nanocomposite film. © The Author(s) 2012.
Keywords: Accurate measurement; Catastrophic failures; Continuous monitoring; Crack evolution; Crack length; Crack monitoring; Crack sensors; Crack sizes; Crack surfaces; Current change; Electrical discharge machining; Epoxy nanocomposites; Fatigue cycles; Gauge factors; Growth monitoring; Host structure; Linear correlation; Maximum load; Measured currents; Metallic hosts; Metallic structures; Nanocomposite thin films; Single-walled carbon; Small load; Stable modes; Strain sensing; Visual inspection; Aluminum; Carbon nanotubes; Crack detection; Epoxy resins; Fatigue testing; Mechanical properties; Nanocomposite films; Nanocomposites; Sensors; Single-walled carbon nanotubes (SWCN); Structural health monitoring; Cracks

VLBI for Gravity Probe B. VII. the evolution of the radio structure of im Pegasi - Bietenholz, M.F.; Bartel, N.; Lebach, D.E.; Ransom, R.R.; Ratner, M.I.; Shapiro, I.I. (Astrophysical Journal, Supplement Series, 2012)
We present measurements of the total radio flux density as well as very long baseline interferometry images of the star, IM Pegasi, which was used as the guide star for the NASA/Stanford relativity mission Gravity ProbeB. We obtained flux densities and images from 35 sessions of observations at 8.4GHz (λ = 3.6cm) between 1997 January and 2005 July. The observations were accurately phase-referenced to several extragalactic reference sources, and we present the images in a star-centered frame, aligned by the position of the star as derived from our fits to its orbital motion, parallax, and proper motion. Both the flux density and the morphology of IM Peg are variable. For most sessions, the emission region has a single-peaked structure, but 25% of the time, we observed a two-peaked (and on one occasion perhaps a three-peaked) structure. On average, the emission region is elongated by 1.4 ± 0.4mas (FWHM), with the average direction of elongation being close to that of the sky projection of the orbit normal. The average length of the emission region is approximately equal to the diameter of the primary star. No significant correlation with the orbital phase is found for either the flux density or the direction of elongation, and no preference for any particular longitude on the star is shown by the emission region. © 2012. The American Astronomical Society. All rights reserved..

Grating couplers in thick rib SOI waveguides for TE and TM polarizations - Alonso-Ramos, C.; Ortega-Moñux, A.; Halir, R.; Zavargo-Peche, L.; Molina-Fernández, I.; Cheben, P.; Xu, D.-X.; Janz, S. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Grating couplers have shown promising performance in terms of coupling efficiency and alignment tolerances as an interface between optical fibers and nanometric silicon-on-insulator (SOI) waveguides. In this paper we review our previous work, where the implementation of a fiber to chip grating coupler in micrometric rib SOI waveguide was demonstrated for the first time, showing measured coupling efficiency of -2.2dB for transverse-electric (TE) polarization. We also propose a new grating design that achieves a calculated coupling efficiency of -2dB for transverse-magnetic (TM) light. © 2012 SPIE.
Keywords: Alignment tolerance; Coupling efficiency; Grating couplers; Grating design; Nanometrics; Rib waveguides; Silicon on insulator waveguide; SOI; SOI waveguides; TM polarization; Transverse-electric polarizations; Efficiency; Optical fiber coupling; Photonic devices; Photonic integration technology; Photonics; Polarization; Waveguides

Gemini high-resolution optical spectrograph conceptual mechanical design - Hill, A.; Anthony, A.; Pazder, J.; Szeto, K.; Thibault, S. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
The Herzberg Institute of Astrophysics was recently selected by the Gemini Observatory as one of the three competing organizations to conduct a conceptual design study for a new Gemini High-Resolution Optical Spectrograph (GHOS). This paper outlines the main features of the mechanical design, including the Cassegrain-mounted science input unit, the bench-mounted spectrograph and the fiber relay system. Topics include the design challenges associated with multi-object fiber relays in the science unit, environmental stability of the spectrograph bench and routing and handling of fibers in the Gemini dome environment. © 2012 SPIE.
Keywords: Design challenges; Echelle; Environmental stability; High resolution; Mechanical design; Multiobject; Optical spectrograph; Pick-off; Relay system; White pupil relay; Astrophysics; Charge coupled devices; Conceptual design; Fibers; Optical resolving power; Spectrographs

Helicobacter pylori 1,3-N-acetylglucosaminyltransferase for versatile synthesis of type 1 and type 2 poly-LacNAcs on N-linked, O-linked and I-antigen glycans - Peng, W.; Pranskevich, J.; Nycholat, C.; Gilbert, M.; Wakarchuk, W.; Paulson, J.C.; Razi, N. (Glycobiology, 2012)
Poly-N-acetyllactosamine extensions on N-and O-linked glycans are increasingly recognized as biologically important structural features, but access to these structures has not been widely available. Here, we report a detailed substrate specificity and catalytic efficiency of the bacterial β3-N-acetylglucosaminyltransferase (β3GlcNAcT) from Helicobacter pylori that can be adapted to the synthesis of a rich diversity of glycans with poly-LacNAc extensions. This glycosyltransferase has surprisingly broad acceptor specificity toward type-1,-2,-3 and-4 galactoside motifs on both linear and branched glycans, found commonly on N-linked, O-linked and I-antigen glycans. This finding enables the production of complex ligands for glycan-binding studies. Although the enzyme shows preferential activity for type 2 (Galβ1-4GlcNAc) acceptors, it is capable of transferring N-acetylglucosamine (GlcNAc) in β1-3 linkage to type-1 (Galβ1-3GlcNAc) or type-3/4 (Gal1-3GalNAc/) sequences. Thus, by alternating the use of the H. pylori β3GlcNAcT with galactosyltransferases that make the 1-4 or 1-3 linkages, various N-linked, O-linked and I-antigen acceptors could be elongated with type-2 and type-1 LacNAc repeats. Finally, one-pot incubation of di-LacNAc biantennary N-glycopeptide with the β3GlcNAcT and GalT-1 in the presence of uridine diphosphate (UDP)-GlcNAc and UDP-Gal, yielded products with 15 additional LacNAc units on the precursor, which was seen as a series of sequential ion peaks representing alternative additions of GlcNAc and Gal residues, on matrix-assisted laser desorption/ionization-time of flight mass spectrometry (MALDI-TOF MS) analysis. Overall, our data demonstrate a broader substrate specificity for the H. pylori β3GlcNAcT than previously recognized and demonstrate its ability as a potent resource for preparative chemo-enzymatic synthesis of complex glycans. © 2012 The Author.
Keywords: beta 3 n acetylglucosaminyltransferase; glycan derivative; glycopeptide; n acetylglucosamine; n acetylglucosaminyltransferase; unclassified drug; aminosugar; blood group I antigen; glycosphingolipid; I-antigen; n acetylglucosamine; n acetyllactosamine; N-acetyllactosamine; polylactosamine; polysaccharide; article; carbon nuclear magnetic resonance; enzyme activity; enzyme substrate complex; Helicobacter pylori; priority journal; protein motif; proton nuclear magnetic resonance; synthesis; biosynthesis; chemistry; enzymology; glycosylation; metabolism; Bacteria (microorganisms); Helicobacter pylori; Acetylglucosamine; Amino Sugars; Glycosphingolipids; Glycosylation; Helicobacter pylori; N-Acetylglucosaminyltransferases; Polysaccharides

Ultrasonic measurement of filler concentration - Fry, C.; Sun, Z. (Annual Technical Conference - ANTEC, Conference Proceedings, 2012)
A novel technique for ultrasonic determination of filler concentration in polymers has been proposed and tested. The new technique senses the overall effect of the filler on the polymer flow behavior and uses this effect to infer the filler concentration. An in-line calibration process has been proposed and implemented for the application of the technique. An average estimation accuracy of better than 0.4% in weight on filler concentration has been achieved.
Keywords: Calibration process; Filler concentration; In-line; Novel techniques; Polymer flows; Ultrasonic inspections; Carbon black; Fillers; Plastic products; Polymers; Ultrasonic testing; Filled polymers

An observed lack of substructure in starless cores. II. super-jeans cores - Schnee, S.; Sadavoy, S.; Di Francesco, J.; Johnstone, D.; Wei, L. (The Astrophysical Journal, 2012)
We present SMA and CARMA continuum and spectral line observations of five dense cores located in the Perseus and Ophiuchus molecular clouds whose masses exceed their thermal Jeans masses. Three of these cores have previously been identified as being starless and two have been classified as being possibly protostellar. We find that one core is certainly protostellar. The other four cores, however, are starless and undetected in both C 18O and 1.3mm continuum emission. These four starless cores have flat density profiles out to at least ∼0.006pc, which is typical for starless cores in general. Density profiles predicted by some collapse models, especially in the early stages of infall, are consistent with our observations. Archival data reveal that these starless cores have significant non-thermal support against collapse, although they may still be unstable. © 2012. The American Astronomical Society. All rights reserved.

Terahertz generation using implanted InGaAs photomixers and multi-wavelength quantum dot lasers - Hou, Y.; Liu, J.R.; Buchanan, M.; Spring Thorpe, A.J.; Poole, P.J.; Liu, H.C.; Wu, K.; Roorda, S.; Zhang, X.P. (Nano-Micro Letters, 2012)
We report on a study of terahertz (THz) generation using implanted InGaAs photomixers and multi-wavelength quantum dot lasers. We carry out InGaAs materials growth, optical characterization, device design and fabrication, and photomixing experiments. This approach is capable of generating a comb of electromagnetic radiation from microwave to terahertz. For shortening photomixer carrier lifetime, we employ proton implantation into an epitaxial layer of lattice matched InGaAs grown on InP. Under a 1.55 μm multimode InGaAs/InGaAsP quantum dot laser excitation, a frequency comb with a constant frequency spacing of 50 GHz generated on the photomixer is measured, which corresponds to the beats of the laser longitudinal modes. The measurement is performed with a Fourier transform infrared spectrometer. This approach affords a convenient method to achieve a broadband multi-peak coherent THz source.

Beam quality conversion factors for parallel-plate ionization chambers in MV photon beams - Muir, B.R.; McEwen, M.R.; Rogers, D.W.O. (Medical Physics, 2012)
Purpose: To investigate the behavior of plane-parallel ion chambers in high-energy photon beams through measurements and Monte Carlo simulations. Methods: Ten plane-parallel ion chamber types were obtained from the major ion chamber manufacturers. Absorbed dose-to-water calibration coefficients are measured for these chambers and k Q factors are determined. In the process, the behaviors of the chambers are characterized through measurements of leakage currents, chamber settling in cobalt-60, polarity and ion recombination behavior, and long-term stability. Monte Carlo calculations of the absorbed dose to the air in the ion chamber and absorbed dose to water are obtained to calculate k Q factors. Systematic uncertainties in Monte Carlo calculated k Q factors are investigated by varying material properties and chamber dimensions. Results: Chamber behavior was variable in MV photon beams, especially with regard to chamber leakage and ion recombination. The plane-parallel chambers did not perform as well as cylindrical chambers. Significant differences up to 1.5 were observed in calibration coefficients after a period of eight months although k Q factors were consistent on average within 0.17. Chamber-to-chamber variations in k Q factors for chambers of the same type were at the 0.2 level. Systematic uncertainties in Monte Carlo calculated k Q factors ranged between 0.34 and 0.50 depending on the chamber type. Average percent differences between measured and calculated k Q factors were - 0.02, 0.18, and - 0.16 for 6, 10, and 25 MV beams, respectively. Conclusions: Excellent agreement is observed on average at the 0.2 level between measured and Monte Carlo calculated k Q factors. Measurements indicate that the behavior of these chambers is not adequate for their use for reference dosimetry of high-energy photon beams without a more extensive QA program than currently used for cylindrical reference-class ion chambers. © 2012 American Association of Physicists in Medicine.
Keywords: article; equipment; Monte Carlo method; photon; radiometry; time; uncertainty; Monte Carlo Method; Photons; Radiometry; Time Factors; Uncertainty

Demonstration of a curved sidewall grating demultiplexer on silicon - Bock, Przemek J.; Cheben, Pavel; Schmid, Jens H.; Velasco, Aitor V.; Delâge, André; Janz, Siegfried; Xu, Dan-Xia; Lapointe, Jean; Hall, Trevor J.; Calvo, María L. (Optics Express, 2012)
We experimentally demonstrate a new type of waveguide multiplexer device designed for silicon photonics, with a crosstalk level as low as -35 dB and an operational wavelength range of 300 nm. A compact device footprint of only 100 × 160 μ m 2 offers an excellent potential for integration with other silicon nanophotonic circuits. © 2012 Optical Society of America.
Keywords: Compact devices; Cross-talk levels; Demultiplexers; Nanophotonic circuits; Silicon photonics; Wavelength ranges; Nanophotonics; Photonics; silicon; article; chemistry; equipment design; equipment failure analysis; instrumentation; nanotechnology; refractometry; surface plasmon resonance; telecommunication; Equipment Design; Equipment Failure Analysis; Nanotechnology; Refractometry; Silicon; Surface Plasmon Resonance; Telecommunications

CFD investigation of noise around a landing gear - Fortin, F.; Syms, J.; Clark, C.; McIlwain, S. (18th AIAA/CEAS Aeroacoustics Conference (33rd AIAA Aeroacoustics Conference), 2012)
A scaled landing gear has recently been tested in the NRC 0.9 m 3/4-open jet wind tunnel. It provided experimental data that were used to investigate the capability and methodology of a CFD flow solver to predict adequately the noise generated on the landing gear surfaces and in its wake. Near-field and far-field noise predictions using CFD were carried out. FFTs of the landing gear surfaces for a given frequency were also carried out. Comparison of the results demonstrates that CFD can predict adequately the noise around complex geometries such as landing gears. © 2012 by the American Institute of Aeronautics and Astronautics, Inc. All rights reserved.
Keywords: Complex geometries; Experimental datum; Far-field noise; Flow solver; Jet wind tunnels; Near-field; Acoustic noise; Computational fluid dynamics; Landing gear (aircraft); Aeroacoustics

Investigation of skin porosity damping effects on free stream disturbance induced unsteady wing loads - Dahdi, B.; Mamou, M.; Khalid, M.; Benissaad, S.; Nemouchi, Z. (Aeronautical Journal, 2012)
Numerical simulations were performed to analyse the possibility of damping abrupt incoming free stream disturbances upon a porous aerofoil using an unsteady Reynolds-averaged Navier-Stokes (URANS) model. To mimic the turbulence disturbance levels that are typically encountered in the atmosphere, two flow configurations were considered. In the first configuration, the unsteadiness of the flow was created with vortices shed from a circular cylinder installed ahead of a WTEA-TE1 aerofoil. The continuous von Kármán shedding vortices contained within the cylinder wake were convected downstream and projected upon the aerofoil. In the second configuration, an instantaneous pair of discrete vortices was created by a rotational snapping of a flat plate, installed upstream of the aerofoil. Solid and porous aerofoil configurations, with porosity settings of 11 and 22%, were applied on 50% of the chord of the aerofoil starting from the leading edge. Both steady and unsteady flow simulations were performed to assess the performance of the porosity under steady and unsteady effects. The steady state flow simulations revealed a noticeable reduction in the aerofoil lift coefficient for the porous aerofoil. For unsteady solutions with a continuous or distinct series of vortices interacting with the aerofoil, the porosity showed insignificant damping of the lift coefficient amplitude. The porosity values investigated in the current exercise had indiscernible effect upon the unsteady lift-load alleviations caused by free stream disturbances.
Keywords: Cylinder wake; Damping effect; Discrete vortices; Disturbance level; Flat plate; Flow configurations; Free stream; Leading edge; Lift coefficient; Shedding vortex; Steady-state flows; Unsteady effects; Unsteady reynolds-averaged navier-stokes; Wing load; Circular cylinders; Damping; Flow simulation; Lift; Porosity; Wakes; Vortex flow

The fine structure of a triexciton in single InAs/GaAs quantum dots - Molas, M.; Gołasa, K.; Furman, M.; Lapointe, J.; Wasilewski, Z.R.; Potemski, M.; Babiński, A. (Acta Physica Polonica A, 2012)
Results of experimental study of multiexcitonic emission related to the p-shell of single self-assembled InAs/GaAs quantum dots are presented. Optical properties of a first emission line to appear from the p-shell of a strongly excited quantum dots are investigated using low-temperature polarization- sensitive micro-photoluminescence measurements. The emission line is attributed to the recombination of a complex of three electrons and holes confined in a dot (neutral triexciton), 3X. It is found that the emission consists of two linearly polarized components and the fine structure splitting is larger than the respective splitting of a neutral exciton. The optical anisotropy of the 3X emission is related to the anisotropy of the quantum dot localizing potential. The axis of the 3X optical anisotropy changes from dot to dot covering broad range within ±50 degrees with respect to the axis defined by the optical anisotropy of a neutral exciton (X). Possible origin of the deviation is discussed.
Keywords: Electrons and holes; Emission lines; Experimental studies; Fine structure splitting; Fine structures; InAs/GaAs quantum dots; Linearly polarized; Low temperatures; Microphotoluminescence; Neutral excitons; P-shell; Self-assembled; Electromagnetic wave emission; Excitons; Optical anisotropy; Optical properties; Polarization; Semiconductor quantum dots

Sizes of galactic globular clusters - Van Den Bergh, S. (The Astrophysical Journal, 2012)
A study is made of deviations from the mean power-law relationship between the Galactocentric distances and the half-light radii of Galactic globular clusters. Surprisingly, deviations from the mean R h versus R gc relationship do not appear to correlate with cluster luminosity, cluster metallicity, or horizontal-branch morphology. Differences in orbit shape are found to contribute to the scatter in the R h versus R gc relationship of Galactic globular clusters. © 2012. The American Astronomical Society. All rights reserved.

A high-performance FPGA platform for adaptive optics real-time control - Zhang, H.; Ljusic, Z.; Hovey, G.; Veran, J.-P.; Herriot, G.; Dumas, M. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Adaptive Optics Real-Time Control systems for next generation ground-based telescopes demand significantly higher processing power, memory bandwidth and I/O capacity on the hardware platform than those for existing control systems. We present a FPGA based high-performance computing platform that is developed at Dominion Radio Astrophysical Observatory and is very suitable for the applications of Adaptive Optics Real-Time Control systems. With maximum of 16 computing blades, 110 TeraMAC/s processing power, 1.8Terabyte/s memory bandwidth and 19.5 Terabit/s I/O capacity, this ATCA architecture platform has enough capacity to perform pixel processing, tomographic wave-front reconstruction and deformable mirror fitting for first and second generation AO systems on 30+-meter class telescopes. As an example, we demonstrate that with only one computing blade, the platform can handle the real time tomography needs of NFIRAOS, the Thirty-Meter Telescope first light facility Multi-Conjugate Adaptive Optics system. The High-Performance FPGA platform is integrated with Board Software Development Kit to provide a complete and fully tested set of interfaces to access the hardware resources. Therefore the firmware development can be focused on unique, user-specific applications. © 2012 SPIE.
Keywords: AdvancedTCA; Architecture platforms; Astrophysical observatory; Deformable mirrors; Ground-based telescopes; Hardware platform; Hardware resources; High-performance computing; Kermode Board; Memory bandwidths; Multi-conjugate adaptive optics systems; NFIRAOS; Pixel processing; Processing power; Real time tomography; Second generation; Software development kit; Terabit; Thirty Meter Telescope; Tomographic; Wave front reconstruction; Adaptive optics; Computer software selection and evaluation; Control systems; Firmware; Hardware; Optical telescopes; Real time control; Telescopes; Tomography; Field programmable gate arrays (FPGA)

Improved stress intensity factor solutions for surface and corner cracks at a hole - Renaud, Guillaume; Liao, Min; Bombardier, Yan (53rd AIAA/ASME/ASCE/AHS/ASC Structures, Structural Dynamics and Materials Conference 2012, 2012)
Detailed three-dimensional finite element (FE) modeling and analysis of quarter-elliptical and semi-elliptical cracks at a hole were carried out. Comparison cases showed that the accuracy of the classical Newman-Raju closed-form stress intensity factor solutions can be improved, especially for the surface crack case and in the thickness direction for the corner crack case. Using the developed FE models, improved stress intensity factor solutions for quarter-circular and semi-circular cracks at a hole were obtained for uniaxial tensile loading. A simple correction approach is also proposed to improve the accuracy of the Newman-Raju solutions for more general cases of quarter-elliptical and semi-elliptical cracks at a hole.
Keywords: corner cracks; correction approaches; modeling and analysis; semi-elliptical crack; surface cracks; thickness direction; three dimensional finite elements; uniaxial tensile loading; finite element method; stress intensity factors; structural dynamics; surface defects; cracks

Consistent point clouds of narrow dpaces using multiscan domain mapping - Sareen, K.K.; Knopf, G.K.; Canas, R. (Computer-Aided Civil and Infrastructure Engineering, 2012)
Three-dimensional (3D) range scanning of large spaces, such as civil structures, generates an immense cloud of 3D points with inconsistent data densities due to the limited positions of the stationary scanner, inaccessible surfaces, and narrow pathways. This density variation is the dominant detrimental factor in extracting accurate scanned shapes. This article introduces an effective scan planning methodology for capturing accurate geometry from long and narrow spaces, which minimizes the need for subsequent data approximations. The technique computes an optimum scanning range for each stationary position of the scanner that limits the density variation to a user-defined value. Three cases are proposed to define the "limited data density" and a FARO®-LS880 laser scanner is used to illustrate the proposed approach that achieves acceptable scanning results in terms of its critical shape capturing capability, overall point cloud density, and accurate point-based visualization. The experimental observations confirm that the accuracy of the scanned data can be improved by registering multiple partial scans with restricted density and positioning the data acquisition device close to the critical features. The latter recommended step decreases the incident angle to the world domain, which, in turn, reduces the surface occlusions and data density variations. © 2011 Computer-Aided Civil and Infrastructure Engineering.
Keywords: Civil structure; Data approximation; Data density; Data-acquisition devices; Density variations; Domain mapping; Experimental observation; Incident angles; Inconsistent data; Large spaces; Laser scanner; Limited data; Multi-scan; Partial scan; Planning methodology; Point cloud; Point-based visualization; Scanning range; Stationary positions; Scanning; Three dimensional; Visualization; Data visualization; accuracy assessment; civil engineering; data acquisition; experimental study; observational method; structural analysis; three-dimensional modeling; visualization

Optical Coherence Tomography for Document Security and Biometrics - Chang, S.; Mao, Y.; Flueraru, C. (Photonic Sensing: Principles and Applications for Safety and Security Monitoring, 2012)

An empirical measure of the rate of white dwarf cooling in 47 Tucanae - Goldsbury, R.; Heyl, J.; Richer, H.B.; Bergeron, P.; Dotter, A.; Kalirai, J.S.; MacDonald, J.; Rich, R.M.; Stetson, P.B.; Tremblay, P.-E.; Woodley, K.A. (The Astrophysical Journal, 2012)
We present an empirical determination of the white dwarf cooling sequence in the globular cluster 47 Tucanae. Using spectral models, we determine temperatures for 887 objects from Wide Field Camera 3 data, as well as 292 objects from data taken with the Advanced Camera for Surveys. We make the assumption that the rate of white dwarf formation in the cluster is constant. Stellar evolution models are then used to determine the rate at which objects are leaving the main sequence, which must be the same as the rate at which objects are arriving on the white dwarf sequence in our field. The result is an empirically derived relation between temperature (T eff and time (t) on the white dwarf cooling sequence. Comparing this result to theoretical cooling models, we find general agreement with the expected slopes between 20,000K and 30,000K and between 6000K and 20,000K, but the transition to the Mestel cooling rate of T efft -0.4 is found to occur at hotter temperatures, and more abruptly than is predicted by any of these models. © 2012. The American Astronomical Society. All rights reserved..

Linear friction welding of a single crystal superalloy - Wanjara, P.; Dalgaard, E.; Gholipour, J.; Larose, J. (Materials Science Forum, 2012)
The effect of forging pressure on linear friction welding (LFW) behaviour of a single crystal Ni-based superalloy was investigated. Crystal orientations of the specimens were controlled and results indicated that welding success is dependent on proximity of the oscillation direction to the <011> direction. Characterization of the welds included optical examination of the microstructural features of the weld and thermomechanically affected zones (TMAZ) in relation to the parent material. Mechanical properties of the welded material examined via microhardness testing showed an increase in strength in the weld zone (WZ). Microstructural examination indicated that some recrystallization occurred in the WZ, as well as a small amount of distortion of the dendrites in the TMAZ. With increased forge pressure, recrystallized grains remaining in the weld were minimized. © 2012 Trans Tech Publications, Switzerland.
Keywords: Forging pressures; Linear friction welding; Microhardness testing; Microstructural examination; Microstructural features; Ni-based superalloys; Parent materials; Recrystallized grains; Single crystal Ni-based superalloys; Single crystal superalloys; Thermomechanically affected zones; Weld zone; Welded materials; Friction welding; Microstructural evolution; Recrystallization (metallurgy); Single crystals; Strength of materials; Superalloys; Welds; Crystal orientation; Friction; Tribology; Welding

Ultra-compact polarization mode converter implemented in a dual-trench silicon-on-insulator waveguide - Velasco, Aitor V.; Calvo, María L.; Cheben, Pavel; Ortega-Moñux, Alejandro; Schmid, Jens H.; Ramos, Carlos Alonso; Fernandez, Íñigo Molina; Lapointe, Jean; Vachon, Martin; Janz, Siegfried; Xu, Dan-Xia (2012 Conference on Lasers and Electro-Optics, CLEO 2012, 2012)
We demonstrate an ultracompact polarization mode converter based on a silicon-on-insulator waveguide with two longitudinal subwavelength trenches. An extinction ratio of 16 dB at 1.5 μm is achieved for a device length of 10 μm. © 2012 OSA.
Keywords: Extinction ratios; Polarization mode converter; Silicon on insulator waveguide; Sub-wavelength; Lasers

The dependence of quenching upon the inner structure of galaxies at 0.5 ≤ z < 0.8 in the deep2/aegis survey - Cheung, E.; Faber, S.M.; Koo, D.C.; Dutton, A.A.; Simard, L.; McGrath, E.J.; Huang, J.-S.; Bell, E.F.; Dekel, A.; Fang, J.J.; Salim, S.; Barro, G.; et al. (The Astrophysical Journal, 2012)
The shutdown of star formation in galaxies is generally termed "quenching." Quenching may occur through a variety of processes, e.g., active galactic nucleus (AGN) feedback, stellar feedback, or the shock heating of gas in the dark matter halo. However, which mechanism(s) is, in fact, responsible for quenching is still in question. This paper addresses quenching by searching for traces of possible quenching processes through their effects on galaxy structural parameters such as stellar mass (M), M/re, surface stellar mass density (M/r 2e), and Sérsic index (n). We analyze the rest-frame U - B color correlations versus these structural parameters using a sample of galaxies in the redshift range 0.5 ≤ z < 0.8 from the DEEP2/AEGIS survey. In addition to global radii, stellar masses, and Sérsic parameters, we also use "bulge" and "disk" photometric measurements from GIM2D fits to HST/ACS V and I images. We assess the tightness of the color relationships by measuring their "overlap regions," defined as the area in color-parameter space in which red and blue galaxies overlap; the parameter that minimizes these overlap regions is considered to be the most effective color discriminator. We find that Sérsic index (n) has the smallest overlap region among all tested parameters and resembles a step function with a threshold value of n = 2.3. There exists, however, a significant population of outliers with blue colors yet high n values that seem to contradict this behavior; they make up 40% of n > 2.3 galaxies. We hypothesize that their Sérsic values may be distorted by bursts of star formation, AGNs, and/or poor fits, leading us to consider central surface stellar mass density, Σ1 kpc, as an alternative to Sérsic index. Not only does Σ1 kpc correct the outliers, but it also forms a tight relationship with color, suggesting that the innermost structure of galaxies is most physically linked with quenching. Furthermore, at z 0.65, the majority of the blue cloud galaxies cannot simply fade onto the red sequence since their GIM2D bulge masses are only half as large on average as the bulge masses of similar red sequence galaxies, thus demonstrating that stellar mass must absolutely increase at the centers of galaxies as they quench. We discuss a two-stage model for quenching in which galaxy star formation rates are controlled by their dark halos while they are still in the blue cloud and a second quenching process sets in later, associated with the central stellar mass buildup. The mass buildup is naturally explained by any non-axisymmetric features in the potential, such as those induced by mergers and/or disk instabilities. However, the identity of the second quenching agent is still unknown. We have placed our data catalog online. © 2012. The American Astronomical Society. All rights reserved.

Astronomical sky quality near Eureka, in the Canadian high arctic - Steinbring, E.; Ward, W.; Drummond, J.R. (Publications of the Astronomical Society of the Pacific, 2012)
Nighttime visible-light sky brightness and transparency are reported for the Polar Environment Research Laboratory (PEARL), located on a 610 m high ridge near the Eureka research station at 80° latitude, on Ellesmere Island, Canada. Photometry of Polaris obtained in the V band with the PEARL All Sky Imager (PASI) over two winters is supported by standard meteorological measurements and visual estimates of sky conditions from sea level. These data show that during the period of the study, 2008/2009 and 2009/2010 October through March, the sky near zenith had a mean surface brightness of 19:7 mag arcsec -2 when the Sun was more than 12° below the horizon, reaching 20:7 mag arcsec -2 during astronomical darkness with no Moon. Skies were without thick cloud and potentially usable for astronomy 86% of the time (extinction <2 mag). Up to 68% of the time was spectroscopic (≤0:5 mag), attenuated by ice crystals, or clear with stable atmospheric transparency. Those conditions can persist for over 100 hr at a time. Further analysis suggests the sky was entirely free of ice crystals (truly photometric) 48 ± 3% of the time at PEARL in winter and that a higher elevation location nearby may be better. © 2012. The Astronomical Society of the Pacific.

New exoplanet surveys in the Canadian High Arctic at 80 Degrees North - Law, N.M.; Sivanandam, S.; Murowinski, R.; Carlberg, R.; Ngan, W.; Salbi, P.; Ahmadi, A.; Steinbring, E.; Halman, M.; Graham, J. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Observations from near the Eureka station on Ellesmere Island, in the Canadian High Arctic at 80° North, benefit from 24-hour darkness combined with dark skies and long cloud-free periods during the winter. Our first astronomical surveys conducted at the site are aimed at transiting exoplanets; compared to mid-latitude sites, the continuous darkness during the Arctic winter greatly improves the survey's detection efficiency for longer-period transiting planets. We detail the design, construction, and testing of the first two instruments: a robotic telescope, and a set of very wide-field imaging cameras. The 0.5m Dunlap Institute Arctic Telescope has a 0.8-square-degree field of view and is designed to search for potentially habitable exoplanets around low-mass stars. The very wide field cameras have several-hundred-square-degree fields of view pointed at Polaris, are designed to search for transiting planets around bright stars, and were tested at the site in February 2012. Finally, we present a conceptual design for the Compound Arctic Telescope Survey (CATS), a multiplexed transient and transit search system which can produce a 10,000-square-degree snapshot image every few minutes throughout the Arctic winter. © 2012 SPIE.
Keywords: Astronomical surveys; Detection efficiency; Exo-planets; Exoplanet; Field of views; Fields of views; High arctic; Low-mass stars; Polaris; Robotic telescope; Search system; Snapshot images; Wide field cameras; Wide field imaging; Airborne telescopes; Conceptual design; Instrument testing; Optical telescopes; Planets; Search engines; Stars; Surveys

A hexane fraction of American ginseng suppresses mouse colitis and associated colon cancer: Anti-inflammatory and proapoptotic mechanisms - Poudyal, D.; Le, P.M.; Davis, T.; Hofseth, A.B.; Chumanevich, A.; Chumanevich, A.A.; Wargovich, M.J.; Nagarkatti, M.; Nagarkatti, P.S.; Windust, A.; Hofseth, L.J. (Cancer Prevention Research, 2012)
Ulcerative colitis is a chronic inflammatory condition associated with a high colon cancer risk. We have previously reported that American ginseng extract significantly reduced the inflammatory parameters of chemically induced colitis. The aim of this study was to further delineate the components of American ginseng that suppress colitis and prevent colon cancer. Among five different fractions of American ginseng (butanol, hexane, ethylacetate, dichloromethane, and water), a hexane fraction has particularly potent antioxidant and proapoptotic properties. The effects of this fraction were shown in a mouse macrophage cell line (ANA-1 cells), in a human lymphoblastoid cell line (TK6), and in an ex vivo model (CD4 +/CD25 - primary effector T cells). A key in vivo finding was that compared with the whole American ginseng extract, the hexane fraction of American ginseng was more potent in treating colitis in a dextran sodium sulfate (DSS) mouse model, as well as suppressing azoxymethane/DSS-induced colon cancer. Furthermore, terminal deoxynucleotidyl transferase-mediated dUTP nick end labeling (TUNEL) labeling of inflammatory cells within the colonic mesenteric lymph nodes was elevated in mice consuming DSS + the hexane fraction of American ginseng. Results are consistent with our in vitro data and with the hypothesis that the hexane fraction of American ginseng has anti-inflammatory properties and drives inflammatory cell apoptosis in vivo, providing a mechanism by which this fraction protects from colitis in this DSS mouse model. This study moves us closer to understanding the molecular components of American ginseng that suppress colitis and prevent colon cancer associated with colitis. ©2012 AACR.
Keywords: acetic acid ethyl ester; azoxymethane; butanol; dextran sulfate; dichloromethane; ginseng extract; hexane; water; antiinflammatory agent; plant extract; animal cell; antiinflammatory activity; antineoplastic activity; antioxidant activity; article; colitis; colon cancer; controlled study; ginseng; human; human cell; in vitro study; lymphoblastoid cell line; macrophage; nick end labeling; nonhuman; priority journal; animal; apoptosis; bioassay; chemistry; colon tumor; inflammation; mass fragmentography; metabolism; methodology; mouse; Panax; tumor cell line; ulcerative colitis; Animals; Anti-Inflammatory Agents; Apoptosis; Biological Assay; Cell Line, Tumor; Colitis, Ulcerative; Colonic Neoplasms; Gas Chromatography-Mass Spectrometry; Hexanes; Humans; In Situ Nick-End Labeling; Inflammation; Mice; Panax; Plant Extracts

Mechanical and microstructural characterization of 45S5 Bioglass® scaffolds for tissue engineering - Aguilar-Reyes, E.A.; León-Patiño, C.A.; Jacinto-Díaz, B.; Lefebvre, L.-P. (Ceramic Transactions, 2012)
Bioglass® 45S5 is the most widely investigated bioactive glass. It was recently demonstrated that this glass is better integrated into bone when the structure is porous. The National Research Council Canada has recently developed a process to produce metallic and ceramic foams using a powder metallurgy approach. Preliminary tests showed that Bioglass® foams can be produced with this process. These foams are produced by foaming a powder mixture composed of Bioglass® particles, a binder and a foaming agent. Highly porous Bioglass® foams (64-79% porosity) were successfully synthesized from dry powder blends. The porosity of the resulting foams was open and the pore size was essentially between 175 and 880 μm in diameter, as required for bone ingrowth. During sintering, crystallization took place and Na6Ca 3Si6O18 (primary phase) and Na 2Ca4(PO4)2SiO4 (secondary phase) were observed. The mechanical compressive strength ranged from 1.7 to 5.5 MPa.
Keywords: 45S5 bioglass; Bone ingrowth; Dry powders; Micro-structural characterization; National Research Council; Powder mixtures; Primary phase; Scaffolds for tissue engineering; Secondary phase; Biological materials; Bone; Ceramic foams; Characterization; Powder metallurgy; Sintering; Sodium; Surface properties; Bioactive glass

The N-terminal β-sheet of the hyperthermophilic endoglucanase from Pyrococcus horikoshii is critical for thermostability - Yang, T.C.; Legault, S.; Kayiranga, E.A.; Kumaran, J.; Ishikawa, K.; Sung, W.L. (Applied and Environmental Microbiology, 2012)
The β-1,4-endoglucanase (EC 3.2.1.4) from the hyperthermophilic archaeon Pyrococcus horikoshii (EGPh) has strong hydrolyzing activity toward crystalline cellulose. When EGPh is used in combination with β-glucosidase (EC 3.2.1.21), cellulose is completely hydrolyzed to glucose at high temperature, suggesting great potential for EGPh in bioethanol industrial applications. The crystal structure of EGPh shows a triosephosphate isomerase (TIM) (β/α)8-barrel fold with an N-terminal antiparallel β-sheet at the opposite side of the active site and a very short C-terminal sequence outside of the barrel structure. We describe here the function of the peripheral sequences outside of the TIM barrel core structure. Sequential deletions were performed from both N and C termini. The activity, thermostability, and pH stability of the expressed mutants were assessed and compared to the wildtype EGPh enzyme. Our results demonstrate that the TIM barrel core is essential for enzyme activity and that the N-terminal β-sheet is critical for enzyme thermostability. Bioinformatics analyses identified potential key residues which may contribute to enzyme hyperthermostability. © 2012, American Society for Microbiology.
Keywords: Active site; Bioinformatics analysis; C-terminal sequences; Core structure; Crystalline cellulose; Glucosidase; High temperature; Hydrolyzing activity; Hyperthermophilic archaeon; Hyperthermophilic endoglucanase; Hyperthermostability; Key residues; N-terminals; PH stability; Pyrococcus horikoshii; TIM barrels; Triosephosphate isomerase; Wild types; Bioinformatics; Cellulose; Enzymes; Ethanol; Glucose; Hydrolysis; Industrial applications; Crystal structure; cellulase; bioinformatics; cellulose; enzyme activity; gene expression; high temperature; thermophilic bacterium; amino acid sequence; article; chemistry; enzyme stability; enzymology; gene deletion; genetics; heat; molecular genetics; pH; protein conformation; protein stability; protein tertiary structure; Pyrococcus horikoshii; Amino Acid Sequence; Cellulase; Enzyme Stability; Hot Temperature; Hydrogen-Ion Concentration; Molecular Sequence Data; Protein Conformation; Protein Stability; Protein Structure, Tertiary; Pyrococcus horikoshii; Sequence Deletion; Archaea; Pyrococcus horikoshii

Hybrid laser-arc welding of HSLA-65 steel plate: Microstructural and mechanical property evaluation of butt welds - Munro, C.; Nolting, A.; Cao, X.; Wanjara, P. (Materials Science Forum, 2012)
High strength low alloy (HSLA) steel, namely HSLA-65, has shown promise as a replacement for more common high strength shipbuilding steels. However, conventional high heat input welding processes can cause significant distortion, often requiring expensive post-weld reworking. Butt welds in HSLA-65 steel were fabricated using a hybrid fibre laser-gas metal arc welding (GMAW) procedure to investigate the efficacy of distortion mitigation via low heat input joining. Heat input from the laser and arc sources were roughly equal at ∼5.2 kW each, and plates were welded in either the laser-leading or arc-leading configuration. In either case, butt welds in ∼9 mm thick plates could be made in a single pass at a total heat input of ∼0.4 kJ/mm. Welding induced distortion was minimal. Analysis of the microstructure and microhardness of the welds is provided, along with some preliminary results of mechanical and impact testing. © 2012 Trans Tech Publications, Switzerland.
Keywords: Arc; Butt welds; Heat input; High heat input welding; High strength; High strength low alloy steels; HSLA-65; Hybrid; Hybrid fibres; Laser-arc; MAG; Mechanical property evaluation; Metal arc welding; Micro-structural; Ship-building steels; Single pass; Steel plates; Thick plate; Welding-induced distortion; Alloy steel; Electric welding; Gas metal arc welding; High strength alloys; Impact testing; Lasers; Mechanical properties; Steel fibers; Welding; Welds; Hybrid materials; Shipbuilding materials; Ships; Strength of materials; High strength steel

The microstructure, creep, and hardness properties of powder metallurgy beta gamma TiAl-4Nb-3Mn alloy - Sawatzky, T.; Seo, D.Y.; Saari, H.; Laurin, D.; Kim, Y.-W. (Materials Science Forum, 2012)
Pre-alloyed beta gamma titanium aluminide powder with a nominal composition of TiAl-4Nb-3Mn is consolidated by hot isostatic pressing. After consolidation, a step cooled heat treatment is performed to homogenize the material and produce a fully lamellar microstructure. Various aging heat treatments are then performed with the goal of forming interfacial beta phase precipitates along lamellar interfaces. The step cooled heat treatment produces a relatively fine microstructure with a lamellar spacing of 0.04 μm and an average lamellar colony size of 60 μm. The aging heat treatments generate beta phase precipitates along lamellar colony boundaries but not along lamellar interfaces, and result in lamellar degredation and grain growth. Constant load tensile creep and room temperature hardness tests are performed on step cooled heat treated and step cooled heat treated and aged specimens. Creep resistance, generally, improves with aging time, even with no interfacial precipitation, and the lamellar degredation that occurs with aging. The microstructures of the as-tested specimens are characterized and related to the creep properties. The hardness values are also compared as a function of selected heat treatment condition and microstructural features. © 2012 Trans Tech Publications, Switzerland.
Keywords: Aging heat treatment; Aging time; Beta-phase; Colony boundary; Colony size; Constant loads; Creep properties; Fine microstructure; Fully lamellar; Gamma-titanium aluminide; Hardness test; Hardness values; Heat treatment conditions; Interfacial precipitation; Lamellar interfaces; Lamellar spacing; Microstructural features; Nominal composition; Room temperature; Tensile creep; Titanium aluminide; Titanium aluminides; Cerium alloys; Creep; Grain growth; Hardness; Hot isostatic pressing; Manganese; Microstructural evolution; Niobium; Phase interfaces; Powder metallurgy; Sintering; Titanium; Titanium alloys; Titanium compounds; Creep resistance; Heat treatment

Mechanical properties of HSLA-65 hybrid laser arc welds - Nolting, A.E.; Munro, C.; Cao, X.J.; Wanjara, P. (Canadian Metallurgical Quarterly, 2012)
High strength steels are finding increasing use in the shipbuilding industry to decrease the weight of vessels for improved maneouverability and fuel efficiency, increased payloads and decreased fabrication costs. High strength low alloy (HSLA) steel, such as HSLA-65, provides a unique combination of strength, weldability and toughness that makes it a particularly attractive choice for many shipbuilding applications. However, as HSLA-65 is a thermomechanically processed steel, it can be susceptible to grain coarsening and softening in the heat affected zone (HAZ) during welding. Low heat input welding procedures such as hybrid laser arc welding are desirable because they minimise HAZ softening and can tolerate gaps between the workpieces better than conventional laser welding. In this paper, the mechanical properties of hybrid laser arc welds, used to join 9?1 mm thick HSLA-65 plates in a single pass, were evaluated. Hardness maps indicated that softening did not occur in the HAZ. Transverse tensile fracture occurred in the base metal, away from the welds, confirming that the fusion zone and HAZ had higher strength than the base metal. Subsized Charpy impact toughness specimens, notched in the HAZ, were typically less tough than the base metal. However, the fracture path typically deviated away from the HAZ, into either the base metal or along the fusion line. © 2012 Crown in Right of Canada.
Keywords: Charpy specimen; HSLA steel; Hybrid laser arc welding; Single pass; Weld strength; Alloy steel; Electric welding; Fracture; High strength alloys; High strength steel; Mechanical properties; Shipbuilding; Shipyards; Tensile strength; Tensile testing; Heat affected zone

A substellar companion to the dusty Pleiades star HD23514 - Rodriguez, D.R.; Marois, C.; Zuckerman, B.; MacIntosh, B.; Melis, C. (The Astrophysical Journal, 2012)
With adaptive optics imaging at Keck observatory, we have discovered a substellar companion to the F6 Pleiades star HD23514, one of the dustiest main-sequence stars known to date (L IR/L * 2%). This is one of the first brown dwarfs discovered as a companion to a star in the Pleiades. The 0.06 M ⊙ late-M secondary has a projected separation of 360AU. The scarcity of substellar companions to stellar primaries in the Pleiades combined with the extremely dusty environment make this a unique system to study. © 2012 The American Astronomical Society. All rights reserved.

Temperature changes during deformation of polycrystalline and nanocrystalline nickel - Chan, T.; Backman, D.; Bos, R.; Sears, T.; Brooks, I.; Erb, U. (Advanced Materials Research, 2012)
Commercially available polycrystalline nickel (grain size: 30 μm) and electrodeposited nanocrystalline nickel (grain size: 30 nm) were analyzed for the effect of stress-induced heat generation during plastic deformation at room temperature. Tensile coupons in conformance to ASTM E8 standard were tested at a strain rate of 10 -1/s to record the amount heat dissipated using a high resolution infrared detector. The maximum temperature increases recorded for nanocrystalline and polycrystalline nickel close to sample fracture were 58° and 70°, respectively. Grain growth in nanocrystalline nickel due to stress-induced heat generation is unlikely since the maximum temperature during deformation is below the previously reported onset temperature for grain growth in nanocrystalline nickel. © (2012) Trans Tech Publications, Switzerland.
Keywords: Grain size; Heat zone; High resolution; Maximum temperature; Nano-crystalline nickel; Nanocrystallines; Onset temperature; Polycrystalline; Room temperature; Stress-induced; Temperature changes; True stress-strain; Deformation; Grain size and shape; Heat generation; Nanocrystalline materials; Nickel; Polycrystalline materials; Strain rate; Stress-strain curves; Grain growth

Human amniotic fluid cells form functional gap junctions with cortical cells - Jezierski, A.; Rennie, K.; Tremblay, R.; Zurakowski, B.; Gruslin, A.; Sikorska, M.; Bani-Yaghoub, M. (Stem Cells International, 2012)
The usage of stem cells is a promising strategy for the repair of damaged tissue in the injured brain. Recently, amniotic fluid (AF) cells have received a lot of attention as an alternative source of stem cells for cell-based therapies. However, the success of this approach relies significantly on proper interactions between graft and host tissue. In particular, the reestablishment of functional brain networks requires formation of gap junctions, as a key step to provide sufficient intercellular communication. In this study, we show that AF cells express high levels of CX43 (GJA1) and are able to establish functional gap junctions with cortical cultures. Furthermore, we report an induction of Cx43 expression in astrocytes following injury to the mouse motor cortex and demonstrate for the first time CX43 expression at the interface between implanted AF cells and host brain cells. These findings suggest that CX43-mediated intercellular communication between AF cells and cortical astrocytes may contribute to the reconstruction of damaged tissue by mediating modulatory, homeostatic, and protective factors in the injured brain and hence warrants further investigation. © 2012 Anna Jezierski et al.
Keywords: connexin 43; amniotic fluid cell; animal cell; animal experiment; animal model; article; astrocyte; brain injury; cell communication; cell culture; controlled study; female; gap junction; human; human cell; in vitro study; in vivo study; motor cortex; mouse; nonhuman; priority journal; protein expression

Soil characteristics more strongly influence soil bacterial communities than land-use type - Kuramae, E.E.; Yergeau, E.; Wong, L.C.; Pijl, A.S.; Van Veen, J.A.; Kowalchuk, G.A. (FEMS Microbiology Ecology, 2012)
To gain insight into the factors driving the structure of bacterial communities in soil, we applied real-time PCR, PCR-denaturing gradient gel electrophoreses, and phylogenetic microarray approaches targeting the 16S rRNA gene across a range of different land usages in the Netherlands. We observed that the main differences in the bacterial communities were not related to land-use type, but rather to soil factors. An exception was the bacterial community of pine forest soils (PFS), which was clearly different from all other sites. PFS had lowest bacterial abundance, lowest numbers of operational taxonomic units (OTUs), lowest soil pH, and highest C N ratios. C N ratio strongly influenced bacterial community structure and was the main factor separating PFS from other fields. For the sites other than PFS, phosphate was the most important factor explaining the differences in bacterial communities across fields. Firmicutes were the most dominant group in almost all fields, except in PFS and deciduous forest soils (DFS). In PFS, Alphaproteobacteria was most represented, while in DFS, Firmicutes and Gammaproteobacteria were both highly represented. Interestingly, Bacillii and Clostridium OTUs correlated with pH and phosphate, which might explain their high abundance across many of the Dutch soils. Numerous bacterial groups were highly correlated with specific soil factors, suggesting that they might be useful as indicators of soil status. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved 79 1 January 2012 10.1111/j.1574-6941.2011.01192.x Research Article Research Articles © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.
Keywords: bacterial DNA; RNA 16S; abundance; electrokinesis; land use change; microbial community; pH; phosphate; phylogenetics; polymerase chain reaction; real time; soil carbon; soil microorganism; soil nitrogen; Alphaproteobacteria; article; bacterium; biodiversity; chemistry; classification; denaturing gradient gel electrophoresis; DNA sequence; Gammaproteobacteria; genetics; growth, development and aging; microbiology; Netherlands; phylogeny; real time polymerase chain reaction; soil; Alphaproteobacteria; Bacteria; Biodiversity; Denaturing Gradient Gel Electrophoresis; DNA, Bacterial; Gammaproteobacteria; Netherlands; Phylogeny; Real-Time Polymerase Chain Reaction; RNA, Ribosomal, 16S; Sequence Analysis, DNA; Soil; Soil Microbiology

Neutral-ionic state correlations in strong-field molecular ionization - Kotur, M.; Zhou, C.; Matsika, S.; Patchkovskii, S.; Spanner, M.; Weinacht, T.C. (Physical Review Letters, 2012)
We study correlations between neutral and ionic states in strong-field molecular ionization. We compare predictions based on Dyson orbital norms and quasistatic semiclassical tunneling theories (Keldysh and molecular orbital Ammosov-Delone-Krainov) with more detailed calculations of strong-field ionization which take into account (i)the Coulomb interaction between the outgoing continuum electron wave packet and the remaining bound electrons and (ii)electron-core interactions that cause distortions of the electronic continuum states during the ionization event. Our results highlight the prominence of electronic rearrangement effects in strong-field ionization with intense ultrafast laser pulses, where the outgoing continuum electron can cause electronic transitions in the parent ion. Calculations and measurements for excited uracil molecules reveal the breakdown of Keldysh-weighted Dyson norm predictions for ionization to different states of the molecular cation in the strong-field regime. © 2012 American Physical Society.
Keywords: Ammosov-Delone-Krainov; Bound electrons; Continuum electrons; Continuum state; Dyson orbital; Electronic transition; Ionic state; Ionization events; Molecular cations; Molecular ionization; Quasi-static; Semiclassical tunneling; Strong field ionization; Forecasting; Molecular orbitals; Ionization

CORS Baade-Wesselink distance to the LMC NGC 1866 blue populous cluster - Molinaro, R.; Ripepi, V.; Marconi, M.; Musella, I.; Brocato, E.; Mucciarelli, A.; Stetson, P.B.; Storm, J.; Walker, A.R. (The Astrophysical Journal, 2012)
We used optical, near-infrared photometry, and radial velocity data for a sample of 11 Cepheids belonging to the young LMC blue populous cluster NGC 1866 to estimate their radii and distances on the basis of the CORS Baade-Wesselink method. This technique, based on an accurate calibration of surface brightness as a function of (U - B), (V - K) colors, allows us to estimate, simultaneously, the linear radius and the angular diameter of Cepheid variables, and consequently to derive their distance. A rigorous error estimate on radii and distances was derived by using Monte Carlo simulations. Our analysis gives a distance modulus for NGC 1866 of 18.51 ± 0.03mag, which is in agreement with several independent results. © 2012 The American Astronomical Society. All rights reserved.

Colorless directional coupler with dispersion engineered sub-wavelength structure - Halir, R.; Maese-Novo, A.; Ortega-Monux, A.; Molina-Fernández, I.; Wangüemert-Pérez, J.G.; Cheben, P.; Xu, D.-X.; Schmid, J.H.; Janz, S. (Optics Express, 2012)
Directional couplers are extensively used devices in integrated optics, but suffer from limited operational wavelength range. Here we use, for the first time, the dispersive properties of sub-wavelength gratings to achieve a fivefold enhancement in the operation bandwidth of a silicon-oninsulator directional coupler. This approach does not compromise the size or the phase response of the device. The sub-wavelength grating based directional coupler we propose covers a 100nm bandwidth with an imbalance of =0.6dB between its outputs, as supported by full 3D FDTD simulations. © 2012 Optical Society of America.
Keywords: 3D FDTD; Dispersive properties; Operation bandwidth; Phase response; Silicon-on-insulators; Sub-wave length grating; Sub-wavelength structures; Wavelength ranges; Diffraction gratings; Dispersion (waves); Optical waveguides; Three dimensional computer graphics; Directional couplers

A thorough investigation of the distance to the supernova remnant CTB109 and its pulsar AXP J2301+5852 - Kothes, R.; Foster, T. (The Astrophysical Journal Letters, 2012)
CTB109 is one of only three Galactic supernova remnants (SNRs) known to harbor an anomalous X-ray pulsar or magnetar. That makes this SNR an object of great importance and a prime target for high-energy astrophysics studies. Those studies rely heavily on the assumed distance to CTB109. There have been three major distance determinations over the last decade, all of which report completely different results. While chaotic distance determinations in the literature are not uncommon for SNRs as a class of object, the wild discrepancy in the distance to CTB109 makes it especially important to revisit and firmly resolve once and for all. In this Letter we bring to bear all available observational information and present a synthesis of evidence that consistently locates CTB109 within or close to the Perseus arm spiral shock, at a distance of 3.2±0.2kpc. © 2012. National Research Council Canada. All rights reserved.

Poly(ethylene glycol) as a compatibilizer and plasticizer of poly(lactic acid)/clay nanocomposites - Rodríguez-Llamazares, S.; Rivas, B.L.; Pérez, M.; Perrin-Sarazin, F. (High Performance Polymers, 2012)
Nanocomposites of poly(lactic acid), PLA, and poly(lactic acid)/poly(ethylene glycol), PLA/PEG, with clay modified with methyl-bis(2-hydroxyethyl) tallow alkyl ammonium cations (Cloisite 30B) were prepared by melt-blending methods. The influence of PEG content on the structure and thermal properties of nanocomposites was investigated. Comparative samples of the PLA/PEG blends with different PEG content were also considered. X-ray diffraction (XRD), transmission electron microscopy (TEM), scanning electron microscopy (SEM), thermogravimetric analysis (TGA) and differential scanning calorimetric (DSC) were used to characterize the studied samples. From XRD, SEM and TEM results, it can be concluded that PEG molecules co-intercalate the silicate layers of Cloisite 30B, together with PLA, allowing better parallel stacking of the silicate layers and the interaction between them. The decrease in the glass transition temperature and crystallization temperature of PLA nanocomposites with an increase in the PEG content, showed the double role of PEG as a plasticizer and as a compatibilizer during the preparation of PLA nanocomposites. © The Author(s) 2012.
Keywords: Ammonium cations; Cloisite; Crystallization temperature; Melt-blending methods; Poly lactic acid; SEM and TEM; Silicate layers; Structure and thermal properties; Transmission electron microscopy tem; XRD; Ammonium compounds; Lactic acid; Nanocomposites; Organoclay; Plasticizers; Polypropylenes; Reinforced plastics; Scanning electron microscopy; Silicates; Thermogravimetric analysis; Transmission electron microscopy; X ray diffraction; Polyethylene glycols

Ex vivo perfusion of the swine heart as a method for pre-transplant assessment - Colah, S.; Freed, D.H.; Mundt, P.; Germscheid, S.; White, P.; Ali, A.; Tian, G.; Large, S.; Falter, F. (Perfusion (United Kingdom), 2012)
We describe a cost-effective, reproducible circuit in a porcine, ex vivo, continuous warm-blood, bi-ventricular, working heart model that has future possibilities for pre-transplant assessment of marginal hearts donated from brain stem dead donors and hearts donated after circulatory determination of death (DCDD).In five consecutive experiments over five days, pressure volume loops were performed. During working mode, the left ventricular end systolic pressure volume relationship (LV ESPVR) was 23.1±11.1 mmHg/ml and the LV preload recruitable stroke work (PRSW) was 67.8±7.2. (Standard PVAN analysis software) (Millar Instruments, Houston, TX, USA)All five hearts were perfused for 219±64 minutes and regained normal cardiac function on the perfusion system.They displayed a significant upward and leftward shift of the end systolic pressure volume relationship, a significant increase in preload recruitable stroke work and minimal stiffness. These hearts could potentially be considered for transplantation. The circuit was effective during reperfusion and working modes whilst proving to be successful in maintaining cardiac function in excess of four hours. Using an autologous prime of approximately 20% haematocrit (Hct), electrolytes and blood gases were easy to control within this period using standard perfusion techniques. © The Author(s) 2012.
Keywords: electrolyte; animal tissue; article; blood gas; brain stem; cost effectiveness analysis; ex vivo study; heart function; heart preload; heart transplantation; heart ventricle pressure; hematocrit; nonhuman; organ donor; organ perfusion; preoperative evaluation; priority journal; reperfusion; swine; systolic blood pressure; Animals; Extracorporeal Circulation; Heart; Heart Transplantation; Myocardial Reperfusion; Myocardial Reperfusion Injury; Organ Preservation; Perfusion; Risk Assessment; Swine; Tissue Donors

Hypochlorite treatment of polyamide membrane for improved reverse osmosis performance - Shao, P.; Kurth, C.J. (Membrane Water Treatment, 2012)
The pH-dependent inter-conversion of the three free chlorine species (Cl2, HOCl, OCl-) present in the aqueous hypochlorite solution was theoretically investigated. Each species was found overwhelmingly present in a characteristic pH range. Hypochlorite treatment of the polyamide membrane was carried out over these pH ranges and various membrane responses were observed. As pH is less than 8, membrane tends to be N-chlorinated by Cl2 and HOCl, and N-chlorinated membrane showed reduced water permeance and salt rejection. As pH rises to 10-12, OCl appears to be the dominating chlorine species. Membrane hydrolysis was found to well interpret the improved water permeance and salt rejection. When the pH is between 8-10, both N-chlorination and hydrolysis contribute to the response of the membrane, and the treated membrane showed improved salt rejection but reduced water permeation. Excessive hydrolysis occurred while the membrane was treated at pH 13 for the much stronger alkalinity.
Keywords: Chlorinating species; Hypochlorite treatment; Membrane chemistry; N-chlorination; Salt rejections; Alkalinity; Chlorination; Chlorine; Hydrolysis; pH; Polyamides; Reverse osmosis; Membranes

On the shapes and structures of high-redshift compact galaxies - Chevance, M.; Weijmans, A.-M.; Damjanov, I.; Abraham, R.G.; Simard, L.; Van Den Bergh, S.; Caris, E.; Glazebrook, K. (The Astrophysical Journal Letters, 2012)
Recent deep Hubble Space Telescope WFC3 imaging suggests that a majority of compact quiescent massive galaxies at z 2 may contain disks. To investigate this claim, we have compared the ellipticity distribution of 31 carefully selected high-redshift massive quiescent compact galaxies to a set of mass-selected ellipticity and Sérsic index distributions obtained from two-dimensional structural fits to 40, 000 nearby galaxies from the Sloan Digital Sky Survey. A Kolmogorov-Smirnov test shows that the distribution of ellipticities for the high-redshift galaxies is consistent with the ellipticity distribution of a similarly chosen sample of massive early-type galaxies. However, the distribution of Sérsic indices for the high-redshift sample is inconsistent with that of local early-type galaxies, and instead resembles that of local disk-dominated populations. The mismatch between the properties of high-redshift compact galaxies and those of both local early-type and disk-dominated systems leads us to conclude that the basic structures of high-redshift compact galaxies probably do not closely resemble those of any single local galaxy population. Any galaxy population analog to the high-redshift compact galaxies that exists at the current epoch is either a mix of different types of galaxies, or possibly a unique class of objects on their own. © 2012. The American Astronomical Society. All rights reserved..

Surface brightness fluctuations as primary and secondary distance indicators - Blakeslee, J.P. (Astrophysics and Space Science, 2012)
The surface brightness fluctuations (SBF) method measures the variance in a galaxy's light distribution arising from fluctuations in the numbers and luminosities of individual stars per resolution element. Once calibrated for stellar population effects, SBF measurements with HST provide distances to early-type galaxies with unrivaled precision. Optical SBF data from HST for the Virgo and Fornax clusters give the relative distances of these nearby fiducial clusters with 2% precision and constrain their internal structures. Observations in hand will allow us to tie the Coma cluster, the standard of comparison for distant cluster studies, into the same precise relative distance scale. The SBF method can be calibrated in an absolute sense either empirically from Cepheids or theoretically from stellar population models. The agreement between the model and empirical zero points has improved dramatically, providing an independent confirmation of the Cepheid distance scale. SBF is still brighter in the near-IR, and an ongoing program to calibrate the method for the F110W and F160W passbands of the Wide Field Camera 3 IR channel will enable accurate distance derivation whenever a large early-type galaxy or bulge is observed in these passbands at distances reaching well out into the Hubble flow. © 2012 UK Crown: National Research Council of Canada.

Modulation of toxin production by the flagellar regulon in Clostridium difficile - Aubry, A.; Hussack, G.; Chen, W.; KuoLee, R.; Twine, S.M.; Fulton, K.M.; Foote, S.; Carrillo, C.D.; Tanha, J.; Logan, S.M. (Infection and Immunity, 2012)
We show in this study that toxin production in Clostridium difficile is altered in cells which can no longer form flagellar filaments. The impact of inactivation of fliC, CD0240, fliF, fliG, fliM, and flhB-fliR flagellar genes upon toxin levels in culture supernatants was assessed using cell-based cytotoxicity assay, proteomics, immunoassay, and immunoblotting approaches. Each of these showed that toxin levels in supernatants were significantly increased in a fliC mutant compared to that in the C. difficile 630 parent strain. In contrast, the toxin levels in supernatants secreted from other flagellar mutants were significantly reduced compared with that in the parental C. difficile 630 strain. Transcriptional analysis of the pathogenicity locus genes (tcdR, tcdB, tcdE, and tcdA) revealed a significant increase of all four genes in the fliC mutant strain, while transcription of all four genes was significantly reduced in fliM, fliF, fliG, and flhB-fliR mutants. These results demonstrate that toxin transcription in C. difficile is modulated by the flagellar regulon. More significantly, mutant strains showed a corresponding change in virulence compared to the 630 parent strain when tested in a hamster model of C. difficile infection. This is the first demonstration of differential flagellum-related transcriptional regulation of toxin production in C. difficile and provides evidence for elaborate regulatory networks for virulence genes in C. difficile. © 2012, American Society for Microbiology.
Keywords: bacterial protein; CD0240 protein; flhB protein; fliC protein; fliF protein; fliM protein; fliR protein; mutant protein; unclassified drug; animal experiment; animal model; article; bacterial genetics; bacterial virulence; Clostridium difficile; controlled study; cytotoxicity; female; flagellum; gene expression; gene inactivation; gene locus; gene regulatory network; genetic transcription; immunoassay; immunoblotting; nonhuman; priority journal; protein secretion; proteomics; regulon; supernatant; toxin synthesis; Animals; Bacterial Proteins; Bacterial Toxins; Clostridium difficile; Cricetinae; Enzyme-Linked Immunosorbent Assay; Female; Flagella; Gene Expression Regulation, Bacterial; Mutation; Proteomics; RNA, Bacterial; Sigma Factor; Transcriptome

Abcg2 deficiency augments oxidative stress and cognitive deficits in Tg-SwDI transgenic mice - Zeng, Y.; Callaghan, D.; Xiong, H.; Yang, Z.; Huang, P.; Zhang, W. (Journal of Neurochemistry, 2012)
Oxidative stress and neuroinflammation play important roles in Alzheimer's disease (AD). ABCG2 is a transporter protein expressed in the brain and involved in GSH transport. To study the roles of Abcg2 in oxidative stress and AD, we cross-bred Tg-SwDI and Abcg2-KO mice and generated Tg-SwDI/Abcg2-KO (double-tg) mice. Brain tissues from double-tg, Tg-SwDI, wild-type, and Abcg2-KO mice at various ages were analyzed. Aβ40 and Aβ42 were detected in Tg-SwDI and double-tg mice. Total brain GSH was decreased and levels of lipid/DNA oxidation were increased in 3-month double-tg compared to Tg-SwDI mice. Low brain GSH was still detected in 9-month double-tg mice. Increased HMOX-1 and MCP-5 expression was observed in 9-month double-tg mice but not in Tg-SwDI mice compared to WT and Abcg2-KO mice. Increased HMOX-1 and decreased ICAM-1 expression were observed in 12-month double-tg mice compared to Tg-SwDI mice. The levels of Nrf-2 expression and activity were decreased in 6-month double-tg mice. Behavioral tests show impaired cognitive/memory performance of 9-month double-tg compared to Tg-SwDI mice as well as WT and Abcg2-KO mice. These results suggest that Abcg2 deficiency increases oxidative stress and alters inflammatory response in the brain and exacerbates cognitive/memory deficit in double-tg mice at different developmental stages. © 2012 National Research Council Canada & The Authors. Journal of Neurochemistry © 2012 International Society for Neurochemistry.
Keywords: beta actin; breast cancer resistance protein; cytokine; DNA; glutathione; intercellular adhesion molecule 1; interleukin 1beta; lipid; monocyte chemotactic protein 5; transcription factor Nrf2; animal experiment; animal model; animal tissue; article; brain tissue; cognitive defect; controlled study; developmental stage; enzyme linked immunosorbent assay; female; gel mobility shift assay; gene expression; genotype; inflammation; lipid oxidation; male; memory disorder; mouse; nonhuman; oxidative stress; priority journal; protein deficiency; protein expression; real time polymerase chain reaction; transgenic mouse; Western blotting; Aging; Amyloid beta-Peptides; Animals; ATP-Binding Cassette Transporters; Cognition Disorders; Cytokines; Disease Progression; DNA; Encephalitis; Enzyme-Linked Immunosorbent Assay; Glutathione; Heme Oxygenase-1; Immunohistochemistry; Intercellular Adhesion Molecule-1; Maze Learning; Mice; Mice, Knockout; Mice, Transgenic; NF-E2-Related Factor 2; Oxidative Stress; Peptide Fragments; Real-Time Polymerase Chain Reaction; Signal Transduction; Mus; Mus musculus

Natural Polymers with Antioxidant Properties: Poly-/oligosaccharides of Marine Origin - Jiao, G.; Yu, G.; Zhao, X.; Zhang, J.; Ewart, H.S. (Antioxidant Polymers: Synthesis, Properties, and Applications, 2012)
In recent decades, poly- and oligosaccharides derived from marine sources including algae, invertebrates and some bacteria display significant antioxidant activities. Development of therapeutic products based on such bioactive poly-/oligosaccharides has been generating considerable interest. Research has shown that the antioxidant properties of marine polysaccharides depend on a number of structural properties, such as the functional groups, molecular weight, and monosaccharide compositions. Structural characteristics may lead to differing mechanisms responsible for antioxidant activities that can be evaluated by various in vitro approaches including l,l-diphenyl-2-picrylhydrazil radical scavenging, ferric reducing antioxidant power, Superoxide radical and hydroxyl radical scavenging assays. This chapter reviews the research on the antioxidant properties of marine poly- and oligosaccharides, with particular emphasis on the relationship between their structural features and antioxidant mechanism. The antioxidant properties of marine poly- and oligosaccharides may lead to their increased use as natural antioxidant agents in food, medical, cosmetic, and other applications. © 2012 Scrivener Publishing LLC.

Supernova 2008bk and its red supergiant progenitor - Van Dyk, S.D.; Davidge, T.J.; Elias-Rosa, N.; Taubenberger, S.; Li, W.; Levesque, E.M.; Howerton, S.; Pignata, G.; Morrell, N.; Hamuy, M.; Filippenko, A.V. (Astronomical Journal, 2012)
We have obtained limited photometric and spectroscopic data for supernova (SN) 2008bk in NGC7793, primarily at ≳ 150 days after explosion. We find that it is a Type II-Plateau (II-P) SN that most closely resembles the low-luminosity SN1999br in NGC4900. Given the overall similarity between the observed light curves and colors of SNe 2008bk and 1999br, we infer that the total visual extinction to SN2008bk (AV = 0.065mag) must be almost entirely due to the Galactic foreground, similar to what has been assumed for SN1999br. We confirm the identification of the putative red supergiant (RSG) progenitor star of the SN in high-quality g′r′i′ images we had obtained in 2007 at the Gemini-South 8m telescope. Little ambiguity exists in this progenitor identification, qualifying it as the best example to date, next to the identification of the star Sk -69°202 as the progenitor of SN1987A. From a combination of photometry of the Gemini images with that of archival, pre-SN, Very Large Telescope JHKs images, we derive an accurate observed spectral energy distribution (SED) for the progenitor. We find from nebular strong-intensity emission-line indices for several H II regions near the SN that the metallicity in the environment is likely subsolar (Z 0.6 Z ⊙). The observed SED of the star agrees quite well with synthetic SEDs obtained from model RSG atmospheres with effective temperature T eff = 3600 50K. We find, therefore, that the star had a bolometric luminosity with respect to the Sun of log (L bol/L ⊙) = 4.57 0.06 and radius R ⊙ = 496 34 R ⊙ at 6 months prior to explosion. Comparing the progenitor's properties with theoretical massive-star evolutionary models, we conclude that the RSG progenitor had an initial mass in the range of 8-8.5 M ⊙. This mass is consistent with, albeit at the low end of, the inferred range of initial masses for SN II-P progenitors. It is also consistent with the estimated upper limit on the initial mass of the progenitor of SN1999br, and it agrees with the low initial masses found for the RSG progenitors of other low-luminosity SNe II-P.

MetaboAnalyst 2.0-a comprehensive server for metabolomic data analysis - Xia, J.; Mandal, R.; Sinelnikov, I.V.; Broadhurst, D.; Wishart, D.S. (Nucleic Acids Research, 2012)
First released in 2009, MetaboAnalyst (www.metaboanalyst.ca) was a relatively simple web server designed to facilitate metabolomic data processing and statistical analysis. With continuing advances in metabolomics along with constant user feedback, it became clear that a substantial upgrade to the original server was necessary. MetaboAnalyst 2.0, which is the successor to MetaboAnalyst, represents just such an upgrade. MetaboAnalyst 2.0 now contains dozens of new features and functions including new procedures for data filtering, data editing and data normalization. It also supports multi-group data analysis, two-factor analysis as well as time-series data analysis. These new functions have also been supplemented with: (i) a quality-control module that allows users to evaluate their data quality before conducting any analysis, (ii) a functional enrichment analysis module that allows users to identify biologically meaningful patterns using metabolite set enrichment analysis and (iii) a metabolic pathway analysis module that allows users to perform pathway analysis and visualization for 15 different model organisms. In developing MetaboAnalyst 2.0 we have also substantially improved its graphical presentation tools. All images are now generated using anti-aliasing and are available over a range of resolutions, sizes and formats (PNG, TIFF, PDF, PostScript, or SVG). To improve its performance, MetaboAnalyst 2.0 is now hosted on a much more powerful server with substantially modified code to take advantage the server's multi-core CPUs for computationally intensive tasks. MetaboAnalyst 2.0 also maintains a collection of 50 or more FAQs and more than a dozen tutorials compiled from user queries and requests. A downloadable version of MetaboAnalyst 2.0, along detailed instructions for local installation is now available as well. © 2012 The Author(s).
Keywords: article; computer; computer program; controlled study; data processing; functional enrichment analysis; image display; Internet; metabolism; metabolite; metabolomics; performance; priority journal; quality control; statistical analysis; time series analysis; web server; Classification; Cluster Analysis; Computer Graphics; Internet; Metabolomics; Software

Plasma protein adsorption to zwitterionic poly (Carboxybetaine Methacrylate) modified surfaces: Chain chemistry and end-group effects on protein adsorption kinetics, adsorbed amounts and immunoblots - Abraham, S.; Bahniuk, M.S.; Unsworth, L.D. (Biointerphases, 2012)
Protein-surface interactions are crucial to the overall biocompatability of biomaterials, and are thought to be the impetus towards the adverse host responses such as blood coagulation and complement activation. Only a few studies hint at the ultra-low fouling potential of zwitterionic poly(carboxybetaine methacrylate) (PCBMA) grafted surfaces and, of those, very few systematically investigate their non-fouling behavior. In this work, single protein adsorption studies as well as protein adsorption from complex solutions (i.e. human plasma) were used to evaluate the non-fouling potential of PCBMA grafted silica wafers prepared by nitroxide- mediated free radical polymerization. PCBMAs used for surface grafting varied in charge separating spacer groups that influence the overall surface charges, and chain endgroups that influence the overall hydrophilicity, thereby, allows a better understanding of these effects towards the protein adsorption for thesematerials. In situ ellipsometry was used to quantify the adsorbed layer thickness and adsorption kinetics for the adsorption of four proteins from single protein buffer solutions, viz, lysozyme, α-lactalbumin, human serum albumin and fibrinogen. Total amount of protein adsorbed on surfaces differed as a function of surface properties and protein characteristics. Finally, immunoblots results showed that human plasma protein adsorption to these surfaces resulted, primarily, in the adsorption of human serum albumin, with total protein adsorbed amounts being the lowest for PCBMA-3 (TEMPO). It was apparent that surface charge and chain hydrophilicity directly influenced protein adsorption behavior of PCBMA systems and are promising materials for biomedical applications. © The Author(s) 2012.

Enhancement in broadband and quasi-omnidirectional antireflection of nanopillar arrays by ion milling - Huang, Z.; Hawkeye, M.M.; Brett, M.J. (Nanotechnology, 2012)
A new technique is developed to fabricate biomimetic antireflection coatings (ARCs). This technique combines a bottom-up fabrication approach (glancing angle deposition, or GLAD) with a top-down engineering process (ion milling). The GLAD technique is first utilized to produce nanopillar arrays (NPAs) with broadened structures, which are subsequently transformed into biomimetic tapered geometries by means of post-deposition ion milling. This structure transformation, due to milling-induced mass redistribution, remarkably decreases reflection over a wide wavelength range (3001700nm) and field of view (angle of incidence <60°with respect to the substrate normal). The milling-induced antireflection enhancement has been demonstrated in the NPAs made of Si, SiO x and TiO 2, illustrating that this integrated technique is readily adapted to a wide variety of materials. Good agreement between simulation and experiment indicates that the enhanced antireflection performance is ascribed to a smoother refractive index transition from the substrate to the air, which improves the impedance match and reduces reflection losses. Additionally, ion bombardment tends to alter the stoichiometry and diminish the crystallographic structure of the NPA materials. The broadband and quasi-omnidirectional antireflection observed establishes the strong competitiveness of this technique with the methods previously reported. © 2012 IOP Publishing Ltd.
Keywords: Angle of Incidence; Anti-reflection; Bottom-up fabrication; Crystallographic structure; Engineering process; Field of views; Glancing Angle Deposition; Impedance match; Integrated techniques; Ion milling; Mass redistribution; Nano-pillar arrays; Post-deposition; Reflection loss; Structure transformations; Tapered geometry; TiO; Topdown; Wavelength ranges; Antireflection coatings; Biomimetics; Competition; Ion bombardment; Refractive index; Stoichiometry; Titanium dioxide; Milling (machining); ion; nanomaterial; article; chemistry; light; materials testing; methodology; particle size; radiation scattering; refractometry; surface plasmon resonance; surface property; ultrastructure; Ions; Light; Materials Testing; Nanostructures; Particle Size; Refractometry; Scattering, Radiation; Surface Plasmon Resonance; Surface Properties

The JCMT Legacy Survey of the Gould Belt: Mapping 13CO and C 18O in Orion A - Buckle, J.V.; Davis, C.J.; di Francesco, J.; Graves, S.F.; Nutter, D.; Richer, J.S.; Roberts, J.F.; Ward-Thompson, D.; White, G.J.; Brunt, C.; Butner, H.M.; Cavanagh, B.; et al. (Monthly Notices of the Royal Astronomical Society, 2012)
The Gould Belt Legacy Survey will map star-forming regions within 500pc, using Heterodyne Array Receiver Programme (HARP), Submillimetre Common-User Bolometer Array 2 (SCUBA-2) and Polarimeter 2 (POL-2) on the James Clerk Maxwell Telescope (JCMT). This paper describes HARP observations of the J= 3 → 2 transitions of 13CO and C 18O towards Orion A. The 15arcsec resolution observations cover 5pc of the Orion filament, including OMC 1 (including BN-KL and Orion bar), OMC 2/3 and OMC 4, and allow a comparative study of the molecular gas properties throughout the star-forming cloud. The filament shows a velocity gradient of ∼1kms -1pc -1 between OMC 1, 2 and 3, and high-velocity emission is detected in both isotopologues. The Orion Nebula and Bar have the largest masses and linewidths, and dominate the mass and energetics of the high-velocity material. Compact, spatially resolved emission from CH 3CN, 13CH 3OH, SO, HCOOCH 3, CH 3CHO and CH 3OCHO is detected towards the Orion Hot Core. The cloud is warm, with a median excitation temperature of ∼24K; the Orion Bar has the highest excitation temperature gas, at >80K. The C 18O excitation temperature correlates well with the dust temperature (to within 40 per cent). The C 18O emission is optically thin, and the 13CO emission is marginally optically thick; despite its high mass, OMC 1 shows the lowest opacities. A virial analysis indicates that Orion A is too massive for thermal or turbulent support, but is consistent with a model of a filamentary cloud that is threaded by helical magnetic fields. The variation of physical conditions across the cloud is reflected in the physical characteristics of the dust cores. We find similar core properties between starless and protostellar cores, but variations in core properties with position in the filament. The OMC 1 cores have the highest velocity dispersions and masses, followed by OMC 2/3 and OMC 4. The differing fragmentation of these cores may explain why OMC 1 has formed clusters of high-mass stars, whereas OMC 4 produces fewer, predominantly low-mass stars. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Relationship between low and high frequencies in δ scuti stars: Photometric kepler and spectroscopic analyses of the rapid rotator KIC8054146 - Breger, M.; Fossati, L.; Balona, L.; Kurtz, D.W.; Robertson, P.; Bohlender, D.; Lenz, P.; Müller, I.; Lüftinger, Th.; Clarke, B.D.; Hall, J.R.; Ibrahim, K.A. (The Astrophysical Journal, 2012)
Two years of Kepler data of KIC8054146 (δSct/γDor hybrid) revealed 349 statistically significant frequencies between 0.54 and 191.36cyclesday -1 (6.3μHz to 2.21mHz). The 117 low frequencies cluster in specific frequency bands, but do not show the equidistant period spacings predicted for gravity modes of successive radial order, n, and reported for at least one other hybrid pulsator. The four dominant low frequencies in the 2.8-3.0cyclesday -1 (32-35μHz) range show strong amplitude variability with timescales of months and years. These four low frequencies also determine the spacing of the higher frequencies in and beyond the δSct pressure-mode frequency domain. In fact, most of the higher frequencies belong to one of three families with spacings linked to a specific dominant low frequency. In the Fourier spectrum, these family regularities show up as triplets, high-frequency sequences with absolutely equidistant frequency spacings, side lobes (amplitude modulations), and other regularities in frequency spacings. Furthermore, within two families the amplitude variations between the low and high frequencies are related. We conclude that the low frequencies (gravity modes, rotation) and observed high frequencies (mostly pressure modes) are physically connected. This unusual behavior may be related to the very rapid rotation of the star: from a combination of high- and low-resolution spectroscopy we determined that KIC8054146 is a very fast rotator (υ sin i=300±20km s -1) with an effective temperature of 7600±200K and a surface gravity log g of 3.9±0.3. Several astrophysical ideas explaining the origin of the relationship between the low and high frequencies are explored. © 2012. The American Astronomical Society. All rights reserved.

Chapter 3: Small molecules and disease - Wishart, D.S. (PLoS Computational Biology, 2012)
"Big" molecules such as proteins and genes still continue to capture the imagination of most biologists, biochemists and bioinformaticians. "Small" molecules, on the other hand, are the molecules that most biologists, biochemists and bioinformaticians prefer to ignore. However, it is becoming increasingly apparent that small molecules such as amino acids, lipids and sugars play a far more important role in all aspects of disease etiology and disease treatment than we realized. This particular chapter focuses on an emerging field of bioinformatics called "chemical bioinformatics" - a discipline that has evolved to help address the blended chemical and molecular biological needs of toxicogenomics, pharmacogenomics, metabolomics and systems biology. In the following pages we will cover several topics related to chemical bioinformatics. First, a brief overview of some of the most important or useful chemical bioinformatic resources will be given. Second, a more detailed overview will be given on those particular resources that allow researchers to connect small molecules to diseases. This section will focus on describing a number of recently developed databases or knowledgebases that explicitly relate small molecules - either as the treatment, symptom or cause - to disease. Finally a short discussion will be provided on newly emerging software tools that exploit these databases as a means to discover new biomarkers or even new treatments for disease. © 2012 David S.
Keywords: article; bioinformatics; chemical bioinformatics; data analysis software; data mining; drug database; knowledge base; metabolomics; pharmacogenomics; systems biology; toxicogenetics; Biological Markers; Computational Biology; Databases, Factual; Disease; Drug Discovery; Humans; Metabolomics; User-Computer Interface

VLBI for Gravity Probe B. V. Proper motion and parallax of the guide star, im Pegasi - Ratner, M.I.; Bartel, N.; Bietenholz, M.F.; Lebach, D.E.; Lestrade, J.-F.; Ransom, R.R.; Shapiro, I.I. (Astrophysical Journal, Supplement Series, 2012)
We present the principal astrometric results of the very long baseline interferometry (VLBI) program undertaken in support of the Gravity Probe B (GP-B) relativity mission. VLBI observations of the GP-B guide star, the RS CVn binary IM Pegasi (HR 8703), yielded positions at 35 epochs between 1997 and 2005. We discuss the statistical assumptions behind these results and our methods for estimating the systematic errors. We find the proper motion of IM Peg in an extragalactic reference frame closely related to the International Celestial Reference Frame 2 (ICRF2) to be -20.83 ± 0.03 ± 0.09masyr -1 in right ascension and -27.27 ± 0.03 ± 0.09masyr -1 in declination. For each component, the first uncertainty is the statistical standard error and the second is the total standard error (SE) including plausible systematic errors. We also obtain a parallax of 10.37 ± 0.07mas (distance: 96.4 ± 0.7pc), for which there is no evidence of any significant contribution of systematic error. Our parameter estimates for the 25day period orbital motion of the stellar radio emission have SEs corresponding to 0.10mas on the sky in each coordinate. The total SE of our estimate of IM Peg's proper motion is 30% smaller than the accuracy goal set by the GP-B project before launch: 0.14masyr -1 for each coordinate of IM Peg's proper motion. Our results ensure that the uncertainty in IM Peg's proper motion makes only a very small contribution to the uncertainty of the GP-B relativity tests. © 2012. The American Astronomical Society. All rights reserved..

Grinding characteristics of a nickel-based alloy using vitrified CBN wheels - Shi, Z.; Elfizy, A.; St-Pierre, B.; Attia, H. (International Journal of Abrasive Technology, 2012)
An experimental study is reported on the grinding of a nickel-based alloy using vitrified CBN wheels. This work was motivated by switching the grinding of fir-tree root forms of jet engine blades from creep-feed grinding with conventional abrasive wheels to vitrified CBN wheels. The objective is to explore process limits and practical grinding parameters for judging the switch in terms of overall costs and productivity. Straight surface grinding experiments were conducted with water-based fluid on rectangular blocks at a fixed wheel speed ν s = 45 m/s, various depths of cut a = 0.05-1.0 mm, and workspeeds ν w = 2-40 mm/s. Grinding and dressing power, forces, surface roughness, and radial wheel wear were measured. Specific material removal rate of 8 mm 3/(mm.s) was reached in rough grinding using a wheel dressed for achieving surface roughness R a = 0.8 μm in finish grinding. It was found that shallow depths of cut combined with fast workspeeds, or less creep-feed modes, are more suitable for achieving high material removal rates with vitrified CBN grinding. Rough grinding is restricted by high grinding temperatures with newly dressed wheels and by chatters with worn wheels. Copyright © 2012 Inderscience Enterprises Ltd.
Keywords: G-ratio; Grinding force; Grinding power; Nickel based alloy; Vitrified CBN; Grinding wheels; Iron alloys; Jet engines; Surface roughness; Vehicles; Wheel dressing; Grinding (machining)

The recent stellar archeology of M31 - The nearest red disk galaxy - Davidge, T.J.; McConnachie, A.W.; Fardal, M.A.; Fliri, J.; Valls-Gabaud, D.; Chapman, S.C.; Lewis, G.F.; Rich, R.M. (The Astrophysical Journal, 2012)
We examine the star-forming history of the M31 disk during the past few hundredMyr. The luminosity functions (LFs) of main-sequence stars at distances R GC > 21kpc (i.e., >4 disk scale lengths) are matched by models that assume a constant star formation rate (SFR). However, at smaller R GC the LFs suggest that during the past 10Myr the SFR was 2-3 times higher than during the preceding 100Myr. The rings of cool gas that harbor a significant fraction of the current star-forming activity are traced by stars with ages 100Myr, indicating that (1) these structures have ages of at least 100Myr and (2) stars in these structures do not follow the same relation between age and random velocity as their counterparts throughout the disks of other spiral galaxies, probably due to the inherently narrow orbital angular momentum distribution of the giant molecular clouds in these structures. The distribution of evolved red stars is not azimuthally symmetric, in the sense that the projected density along the northeast segment of the major axis is roughly twice that on the opposite side of the galaxy. The northeast arm of the major axis thus appears to be a fossil star-forming area that dates to intermediate epochs. Such a structure may be the consequence of interactions with a companion galaxy. © 2012. The American Astronomical Society. All rights reserved..

Characterization of single-domain antibodies with an engineered disulfide bond - Hussack, G.; MacKenzie, C.R.; Tanha, J. (Methods in Molecular Biology, 2012)
Camelidae single-domain antibodies (VHHs) represent a unique class of emerging therapeutics. Similar to other recombinant antibody fragments (e.g., Fabs, scFvs), VHHs are amenable to library screening and selection, but benefit from superior intrinsic biophysical properties such as high refolding efficiency, high solubility, no tendency for aggregation, resistance to proteases and chemical denaturants, and high expression, making them ideal agents for antibody-based drug design. Despite these favorable biophysical characteristics, further improvements to VHH stability are desirable when considering applications in adverse environments like high heat, low humidity, pH extremes, and the acidic, protease-rich gastrointestinal tract. Recently, the introduction of a disulfide bond into the hydrophobic core of camelid VHHs increased antibody thermal and conformational stability. Here, we present additional protocols for characterizing the effects of the introduced disulfide bond on a panel of llama VHHs. Specifically, we employ mass spectrometry fingerprinting analysis of VHH peptides to confirm the presence of the introduced disulfide bond, size exclusion chromatography, and surface plasmon resonance to examine the effects on aggregation state and target affinity, and circular dichroism spectroscopy and protease digestion assays to assess the effects on thermal and proteolytic stability. The disulfide bond stabilization strategy can be incorporated into antibody library design and should lead to hyperstabilized single-domain antibodies (VHHs, VHs), and possibly Fabs and scFvs, if selection pressures such as denaturants or proteases are introduced during antibody selection. © 2012 Springer Science+Business Media, LLC.
Keywords: Camelidae single domain antibody; nanobody; unclassified drug; bacterial toxin; disulfide; article; circular dichroism; disulfide bond; gel permeation chromatography; mass spectrometry; priority journal; protein degradation; surface plasmon resonance; thermostability; amino acid sequence; animal; Artiodactyla; chemistry; metabolism; molecular genetics; protein binding; protein engineering; protein folding; protein stability; solubility; temperature; Amino Acid Sequence; Animals; Bacterial Toxins; Camelids, New World; Disulfides; Molecular Sequence Data; Protein Binding; Protein Engineering; Protein Folding; Protein Stability; Proteolysis; Single-Domain Antibodies; Solubility; Temperature

Pulsed laser deposition of pseudocapacitive metal oxide thin films for supercapacitor applications - Yang, D. (Materials Science Forum, 2012)
Thin films of manganese oxides have been prepared by pulsed laser deposition (PLD) process on silicon and stainless steel substrates at different substrate temperatures and oxygen gas pressures. By proper selection of temperature and oxygen pressure during the PLD process, pure phases of Mn 2O 3, Mn 3O 4 as well as an amorphous phase of MnO x were successfully fabricated and characterized by X-ray diffraction. The pseudo-capacitance behaviors of those manganese oxides of different phases have also been evaluated by the electrochemical cyclic voltammetry in 0.1 M Na 2SO 4 aqueous electrolyte. Their specific current and capacitance determined at different scan rates were calculated and compared. The results show that polycrystalline Mn 2O 3 phase has the highest specific current and capacitance, while the values for polycrystalline Mn 3O 4 films are the lowest. The amorphous phase MnOx films have the values sitting in between those of Mn 2O 3 and Mn 3O 4. The specific capacitance of Mn 2O 3 films reaches 200 F/g at 1 mV/sec scan with excellent stability and cyclic durability. This work has demonstrated that PLD is a very promising technique for supercapacitor material research due to its excellent flexibility and capability of controlling microstructures and phases of various materials. © 2012 Trans Tech Publications, Switzerland.
Keywords: Amorphous phase; Aqueous electrolyte; Cyclic durability; Different substrates; Electrochemical capacitor; Material research; Metal oxide thin films; Oxygen gas pressure; Oxygen pressure; PLD process; Polycrystalline; Pseudocapacitive; Scan rates; Specific capacitance; Stainless steel substrates; Super capacitor; Supercapacitor application; Ultracapacitors; Amorphous films; Amorphous materials; Capacitance; Capacitors; Cyclic voltammetry; Deposition; Manganese; Manganese oxide; Metallic compounds; Oxide films; Oxides; Oxygen; Programmable logic controllers; Pulsed laser deposition; Sodium; Stainless steel; Substrates; Thin films; Vapor deposition; X ray diffraction; Pulsed lasers; Manganese

Detailed high-accuracy megavoltage transmission measurements: A sensitive experimental benchmark of EGSnrc - Ali, E.S.M.; McEwen, M.R.; Rogers, D.W.O. (Medical Physics, 2012)
Purpose: There are three goals for this study: (a) to perform detailed megavoltage transmission measurements in order to identify the factors that affect the measurement accuracy, (b) to use the measured data as a benchmark for the EGSnrc system in order to identify the computational limiting factors, and (c) to provide data for others to benchmark Monte Carlo codes. Methods: Transmission measurements are performed at the National Research Council Canada on a research linac whose incident electron parameters are independently known. Automated transmission measurements are made on-axis, down to a transmission value of ∼1.7, for eight beams between 10 MV (the lowest stable MV beam on the linac) and 30 MV, using fully stopping Be, Al, and Pb bremsstrahlung targets and no fattening filters. To diversify energy differentiation, data are acquired for each beam using low-Z and high-Z attenuators (C and Pb) and Farmer chambers with low-Z and high-Z buildup caps. Experimental corrections are applied for beam drifts (2), polarity (2.5 typical maximum, 6 extreme), ion recombination (0.2), leakage (0.3), and room scatter (0.8)-the values in parentheses are the largest corrections applied. The experimental setup and the detectors are modeled using EGSnrc, with the newly added photonuclear attenuation included (up to a 5.6 effect). A detailed sensitivity analysis is carried out for the measured and calculated transmission data. Results: The developed experimental protocol allows for transmission measurements with 0.4 uncertainty on the smallest signals. Suggestions for accurate transmission measurements are provided. Measurements and EGSnrc calculations agree typically within 0.2 for the sensitivity of the transmission values to the detector details, to the bremsstrahlung target material, and to the incident electron energy. Direct comparison of the measured and calculated transmission data shows agreement better than 2 for C (3.4 for the 10 MV beam) and typically better than 1 for Pb. The differences can be explained by acceptable photon cross section changes of 0.4. Conclusions: Accurate transmission measurements require accounting for a number of influence quantities which, if ignored, can collectively introduce errors larger than 10. Accurate transmission calculations require the use of the most accurate data and physics options available in EGSnrc, particularly the more accurate bremsstrahlung angular sampling option and the newly added modeling of photonuclear attenuation. Comparison between measurements and calculations implies that EGSnrc is accurate within 0.2 for relative ion chamber response calculations. Photon cross section uncertainties are the ultimate limiting factor for the accuracy of the calculated transmission data (Monte Carlo or analytical). © 2012 American Association of Physicists in Medicine.
Keywords: article; instrumentation; methodology; Monte Carlo method; photon; quality control; radiation scattering; radiometry; Benchmarking; Monte Carlo Method; Photons; Radiometry; Scattering, Radiation

Identification and recombinant expression of anandamide hydrolyzing enzyme from Dictyostelium discoideum - Neelamegan, D.; Schoenhofen, I.C.; Richards, J.C.; Cox, A.D. (BMC Microbiology, 2012)
Background: Anandamide (Arachidonoyl ethanolamide) is a potent bioactive lipid studied extensively in humans, which regulates several neurobehavioral processes including pain, feeding and memory. Bioactivity is terminated when hydrolyzed into free arachidonic acid and ethanolamine by the enzyme fatty acid amide hydrolase (FAAH). In this study we report the identification of a FAAH homolog from Dictyostelium discoideum and its function to hydrolyze anandamide. Results: A putative FAAH DNA sequence coding for a conserved amidase signature motif was identified in the Dictyostelium genome database and the corresponding cDNA was isolated and expressed as an epitope tagged fusion protein in either E.coli or Dictyostelium. Wild type Dictyostelium cells express FAAH throughout their development life cycle and the protein was found to be predominantly membrane associated. Production of recombinant HIS tagged FAAH protein was not supported in E.coli host, but homologous Dictyostelium host was able to produce the same successfully. Recombinant FAAH protein isolated from Dictyostelium was shown to hydrolyze anandamide and related synthetic fatty acid amide substrates. Conclusions: This study describes the first identification and characterisation of an anandamide hydrolyzing enzyme from Dictyostelium discoideum, suggesting the potential of Dictyostelium as a simple eukaryotic model system for studying mechanisms of action of any FAAH inhibitors as drug targets. © 2012 Monecke et al.; licensee BioMed Central Ltd.
Keywords: anandamide; epitope; fatty acid amidase; hybrid protein; article; catalysis; Dictyostelium discoideum; DNA sequence; Escherichia coli; fruiting body; in vivo study; life cycle; nonhuman; nucleotide sequence; protein expression; protein localization; sequence analysis; Amidohydrolases; Amino Acid Sequence; Arachidonic Acids; Cloning, Molecular; Computational Biology; Dictyostelium; DNA, Complementary; Endocannabinoids; Escherichia coli; Gene Expression; Gene Expression Profiling; Membrane Proteins; Molecular Sequence Data; Polyunsaturated Alkamides; Recombinant Proteins; Sequence Alignment; Sequence Homology, Amino Acid; Substrate Specificity; Dictyostelium; Dictyostelium discoideum; Eukaryota

Estimating diets of Atlantic salmon (Salmo salar) using fatty acid signature analyses; validation with controlled feeding studies - Budge, S.M.; Penney, S.N.; Lall, S.P. (Canadian Journal of Fisheries and Aquatic Sciences, 2012)
Diets incorporating homogeneous binary mixtures of herring or krill oil were fed to Atlantic salmon (Salmo salar) for 22 weeks, and belly flap and muscle tissues were then analyzed for fatty acid (FA) composition. Quantitative fatty acid signature analysis (QFASA) was able to estimate proportions of major dietary components within ~10% of actual values, but the accuracy of the estimates depended on the FA set and calibration coefficients (CC) used in the modelling. FAs present at low levels had little influence on estimates, despite having only dietary sources; the FA set used in the modelling must incorporate the major FAs in tissues to ensure accurate estimates of diet. CC, which reflect modifications that consumers make to dietary FAs, were similar in the two tissues but varied with diet. When CC were applied to correct for fish metabolism, QFASA tended to overestimate the dietary component that had been fed to determine the CC. Diet estimates were most accurate when CC that had been developed from feeding the krill oil-based diet were applied. This first application of QFASA to fish therefore establishes a set of FAs and CC to begin to investigate diets of salmonids.
Keywords: calibration; diet; fatty acid; metabolism; muscle; quantitative analysis; salmonid fishery; Clupeidae; Euphausiacea; Salmo salar; Salmonidae

The human phosphotyrosine signaling network: Evolution and hotspots of hijacking in cancer - Li, L.; Tibiche, C.; Fu, C.; Kaneko, T.; Moran, M.F.; Schiller, M.R.; Li, S.S.-C.; Wang, E. (Genome Research, 2012)
Phosphotyrosine (pTyr) signaling, which plays a central role in cell-cell and cell-environment interactions, has been considered to be an evolutionary innovation in multicellular metazoans. However, neither the emergence nor the evolution of the human pTyr signaling system is currently understood. Tyrosine kinase (TK) circuits, each of which consists of a TK writer, a kinase substrate, and a related reader, such as Src homology (SH) 2 domains and pTyr-binding (PTB) domains, comprise the core machinery of the pTyr signaling network. In this study, we analyzed the evolutionary trajectories of 583 literature-derived and 50,000 computationally predicted human TK circuits in 19 representative eukaryotic species and assigned their evolutionary origins. We found that human TK circuits for intracellular pTyr signaling originated largely from primitive organisms, whereas the inter- or extracellular signaling circuits experienced significant expansion in the bilaterian lineage through the "back- wiring" of newly evolved kinases to primitive substrates and SH2/PTB domains. Conversely, the TK circuits that are involved in tissue-specific signaling evolved mainly in vertebrates by the back-wiring of vertebrate substrates to primitive kinases and SH2/PTB domains. Importantly, we found that cancer signaling preferentially employs the pTyr sites, which are linked to more TK circuits. Our work provides insights into the evolutionary paths of the human pTyr signaling circuits and suggests the use of a network approach for cancer intervention through the targeting of key pTyr sites and their associated signaling hubs in the network. © 2012, Published by Cold Spring Harbor Laboratory Press.
Keywords: phosphotyrosine; protein SH2; protein tyrosine kinase; article; cell interaction; eukaryote; human; intracellular signaling; neoplasm; nonhuman; priority journal; protein binding; protein expression; Animals; Cell Communication; Cell Membrane; Cytoplasm; Evolution, Molecular; Humans; Models, Genetic; Neoplasms; Organ Specificity; Phosphorylation; Phosphotyrosine; Phylogeny; Protein Binding; Protein-Tyrosine Kinases; Signal Transduction; src Homology Domains; Bilateria; Eukaryota; Metazoa; Vertebrata

Amniotic stem cells: Potential in regenerative medicine - Bani-Yaghoub, M.; Wilson, P.; Hengstschläger, M.; Nikaido, T.; Pei, D. (Stem Cells International, 2012)
Keywords: bone morphogenetic protein; connexin 43; transcription factor; acute lung injury; adult stem cell; amniocentesis; amnion; amniotic stem cell; cell cloning; cell communication; cell culture; cell differentiation; cell isolation; chronic lung injury; connective tissue; editorial; embryo cell; embryonic stem cell; flow cytometry; gap junction; human; immunocytochemistry; immunomodulation; lung injury; medical research; mesenchymal stem cell; paracrine signaling; pluripotent stem cell; priority journal; protein expression; regenerative medicine; stem cell; stem cell transplantation; tissue engineering; tissue regeneration; tissue repair

The discovery of an ultra-faint star cluster in the constellation of Ursa Minor - Muñoz, R.R.; Geha, M.; Côté, P.; Vargas, L.C.; Santana, F.A.; Stetson, P.; Simon, J.D.; Djorgovski, S.G. (The Astrophysical Journal Letters, 2012)
We report the discovery of a new ultra-faint globular cluster in the constellation of Ursa Minor, based on stellar photometry from the MegaCam imager at the Canada-France-Hawaii Telescope. We find that this cluster, Muñoz 1, is located at a distance of 45 ± 5kpc and at a projected distance of only 45′ from the center of the Ursa Minor dwarf spheroidal galaxy. Using a maximum-likelihood technique we measure a half-light radius of 05, or equivalently 7pc, and an ellipticity consistent with being zero. We estimate its absolute magnitude to be M V = -0.4 ± 0.9, which corresponds to L V = 120 +160 - 65 L· and we measure a heliocentric radial velocity of -137 ± 4kms -1 based on Keck/DEIMOS spectroscopy. This new satellite is separate from Ursa Minor by 30kpc and 110km s -1 suggesting the cluster is not obviously associated with the dSph, despite the very close angular separation. Based on its photometric properties and structural parameters we conclude that Muñoz 1 is a new ultra-faint stellar cluster. Along with Segue 3 this is one of the faintest stellar clusters known to date. © 2012. The American Astronomical Society. All rights reserved..

199.5 K operation of THz quantum cascade lasers - Fathololoumi, S.; Dupont, E.; Chan, C.W.I.; Wasilewski, Z.R.; Laframboise, S.R.; Ban, D.; Matyas, A.; Jirauschek, C.; Hu, Q.; Liu, H.C. (2012 Conference on Lasers and Electro-Optics, CLEO 2012, 2012)
The density matrix based model is employed to design a THz quantum cascade laser with optimized oscillator strength and improved injection tunneling. A maximum operating temperature of 199.5 K has been recorded at 3.22 THz (1.28hω/kκB). © 2012 OSA.
Keywords: Density matrix; Operating temperature; Oscillator strengths; THz quantum cascade lasers; Quantum cascade lasers; Lasers

Cj1136 is required for lipooligosaccharide biosynthesis, hyperinvasion, and chick colonization by Campylobacter jejuni - Javed, M.A.; Cawthraw, S.A.; Baig, A.; Li, J.; McNally, A.; Oldfield, N.J.; Newell, D.G.; Manning, G. (Infection and Immunity, 2012)
Campylobacter jejuni is a major cause of bacterial food-borne enteritis worldwide, and invasion into intestinal epithelial cells is an important virulence mechanism. Recently we reported the identification of hyperinvasive C. jejuni strains and created a number of transposon mutants of one of these strains, some of which exhibited reduced invasion into INT-407 and Caco-2 cells. In one such mutant the transposon had inserted into a homologue of cj1136, which encodes a putative galactosyltransferase according to the annotation of the C. jejuni NCTC11168 genome. In the current study, we investigated the role of cj1136 in C. jejuni virulence, lipooligosaccharide (LOS) biosynthesis, and host colonization by targeted mutagenesis and complementation of the mutation. The cj1136 mutant showed a significant reduction in invasion into human intestinal epithelial cells compared to the wild-type strain 01/51. Invasion levels were partially restored on complementing the mutation. The inactivation of cj1136 resulted in the production of truncated LOS, while biosynthesis of a full-length LOS molecule was restored in the complemented strain. The cj1136 mutant showed an increase in sensitivity to the bile salts sodium taurocholate and sodium deoxycholate and significantly increased sensitivity to polymyxin B compared to the parental strain. Importantly, the ability of the mutant to colonize 1-day-old chicks was also significantly impaired. This study confirms that a putative galactosyltransferase encoded by cj1136 is involved in LOS biosynthesis and is important for C. jejuni virulence, as disruption of this gene and the resultant truncation of LOS affect both colonization in vivo and invasiveness in vitro. © 2012, American Society for Microbiology.
Keywords: bile salt; deoxycholate sodium; lipooligosaccharide; polymyxin B; taurocholic acid; animal experiment; animal model; antibiotic resistance; antibiotic sensitivity; article; bacterial colonization; bacterial gene; bacterial mutation; bacterial virulence; bacterium adherence; Campylobacter jejuni; carbohydrate synthesis; cell invasion; chick; controlled study; enteritis; environmental stress; food poisoning; gene disruption; gene inactivation; host pathogen interaction; in vitro study; in vivo study; intestine epithelium cell; mutagenesis; nonhuman; priority journal; Animals; Campylobacter jejuni; Cell Line; Chickens; Disease Models, Animal; DNA Transposable Elements; Epithelial Cells; Galactosyltransferases; Gene Deletion; Genetic Complementation Test; Humans; Lipopolysaccharides; Mutagenesis, Insertional; Virulence Factors

Combining structural brain changes improves the prediction of Alzheimer's disease and mild cognitive impairment - Zhang, N.; Song, X.; Zhang, Y. (Dementia and Geriatric Cognitive Disorders, 2012)
Background: Several structural brain changes have been associated with Alzheimer's disease (AD). This study investigated the prediction of AD by combining multiple brain changes with the hallmark medial temporal lobe atrophy (MTA). Methods: High-resolution magnetic resonance imaging (MRI) data of people with mild AD (n = 39), mild cognitive impairment (MCI; n = 82), and of healthy controls (HC; n = 58) were obtained at baseline. Among these people, 26 AD, 53 MCI, and 46 HC subjects had 24-month follow-up MRI scans. Bilateral MTA was evaluated using a medial temporal lobe atrophy scale (MTAS). Common changes in the aging brain were summarized using a brain atrophy and lesion index (BALI). The performance of the MTAS, BALI, and a score combining both, using a logistic regression model, were assessed. Results: The MTAS and BALI scores were closely correlated (r2 > 0.56); each differed between the diagnostic groups. Having an unfavorable MTAS score was associated with an increased risk of MCI-AD conversion (OR = 3.71, p = 0.039), adjusted for age, sex, and education; having an unfavorable BALI score marginally contributed to such risks (OR = 4.08, p = 0.080). Combining MTAS and BALI components resulted in a greater OR (8.99, p = 0.007) and an improved predictive accuracy (75.9%, p = 0.002). Conclusion: Multiple structural changes have an additive effect on AD. The data support potential future roles of combining multiple coexisting structural changes to benefit AD diagnosis, progression monitoring, and/or treatment effect evaluation. Copyright © 2012 S. Karger AG, Basel.
Keywords: accuracy; aged; aging; Alzheimer disease; article; brain atrophy; controlled study; correlation analysis; disease predisposition; female; follow up; human; major clinical study; male; medial temporal lobe atrophy; mild cognitive impairment; nuclear magnetic resonance imaging; predictive value; priority journal; prognosis; Aged; Aged, 80 and over; Aging; Alzheimer Disease; Atrophy; Brain; Case-Control Studies; Disease Progression; Female; Humans; Magnetic Resonance Imaging; Male; Middle Aged; Mild Cognitive Impairment; Organ Size; Predictive Value of Tests; Prognosis; Sensitivity and Specificity; Temporal Lobe

Phosphorylcholine allows for evasion of bactericidal antibody by haemophilus influenzae - Clark, S.E.; Snow, J.; Li, J.; Zola, T.A.; Weiser, J.N. (PLoS Pathogens, 2012)
The human pathogen Haemophilus influenzae has the ability to quickly adapt to different host environments through phase variation of multiple structures on its lipooligosaccharide (LPS), including phosphorylcholine (ChoP). During colonization with H. influenzae, there is a selection for ChoP+ phase variants. In a murine model of nasopharyngeal colonization, this selection is lost in the absence of adaptive immunity. Based on previous data highlighting the importance of natural antibody in limiting H. influenzae colonization, the effect of ChoP expression on antibody binding and its bactericidal activity was investigated. Flow cytometric analysis revealed that ChoP+ phase variants had decreased binding of antibody to LPS epitopes compared to ChoP- phase variants. This difference in antibody binding correlated with increased survival of ChoP+ phase variants in the presence of antibody-dependent, complement-mediated killing. ChoP+ phase variants were also more resistant to trypsin digestion, suggesting a general effect on the physical properties of the outer membrane. Moreover, ChoP-mediated protection against antibody binding correlated with increased resilience of outer membrane integrity. Collectively, these data suggest that ChoP expression provides a selective advantage during colonization through ChoP-mediated effects on the accessibility of bactericidal antibody to the cell surface. © 2012 Clark et al.
Keywords: bacterium antibody; lipopolysaccharide; phosphorylcholine; trypsin; lipopolysaccharide; adaptive immunity; animal experiment; antigen binding; article; bacterial colonization; bactericidal activity; cell surface; controlled study; flow cytometry; Haemophilus influenzae; mouse; nasopharynx; nonhuman; outer membrane; protein expression; survival; adaptive immunity; animal; antibody combining site; Bagg albino mouse; cell membrane; host pathogen interaction; human; immune evasion; immunology; mouse mutant; pathogenicity; Haemophilus influenzae; Murinae; Adaptive Immunity; Animals; Binding Sites, Antibody; Cell Membrane; Haemophilus influenzae; Host-Pathogen Interactions; Humans; Immune Evasion; Lipopolysaccharides; Mice; Mice, Inbred BALB C; Mice, SCID; Phosphorylcholine

Detailed numerical simulation of single-walled carbon nanotube synthesis in a radio-frequency induction thermal plasma system - Esfarjani, S.A.; Dworkin, S.B.; Mostaghimi, J.; Kim, K.S.; Kingston, C.T.; Simard, B.; Soucy, G. (Journal of Physics: Conference Series, 2012)
2D axisymmetric numerical calculations are conducted to model the thermo-fluid fields and chemical reactions leading to the formation of SWCNTs in an RF plasma system. A modified version of the SWCNT "reduced" chemical model is used to estimate the formation of SWCNT in an RF plasma system for the first time. The "reduced" model incorporates 14 species and 36 chemical reactions to predict the formation of metal and carbon clusters and SWCNTs. By combing the chemistry model into the RF plasma CFD code, the formation and development of carbon and metal catalyst clusters and their reactions which produce SWCNTs are shown. The chemistry model is shown to under-predict the yield rate of SWCNT. In order to better predict the yield rate, a sensitivity analysis is performed to modify the dominant reaction rates. The modified model predicts the yield of SWCNTs correctly within the range reported experimentally. However, more studies should be conducted to validate the accuracy of the model for different operating conditions.
Keywords: Axisymmetric; CFD codes; Chemical model; Chemistry models; Different operating conditions; Induction thermal plasma; Metal catalyst; Modified model; Numerical calculation; Radio frequencies; RF plasma; RF plasma systems; Single-walled carbon; Thermofluid fields; Yield rates; Carbon clusters; Chemical reactions; Computational fluid dynamics; Computer simulation; Forecasting; Plasma devices; Reaction rates; Single-walled carbon nanotubes (SWCN); Wave plasma interactions; Plasma theory

Performance modeling for the RAVEN Multi-Object Adaptive Optics demonstrator - Andersen, D.R.; Jackson, K.J.; Blain, C.; Bradley, C.; Correia, C.; Ito, M.; Lardière, O.; Véran, J.-P. (Publications of the Astronomical Society of the Pacific, 2012)
RAVEN will be a Multi-Object Adaptive Optics (MOAO) technology and science demonstrator on the Subaru telescope. The baseline design calls for three natural guide star (NGS) wavefront sensors (WFS) and two science pickoff arms that will patrol a ~2′ diameter field of regard (FOR). Sky coverage is an important consideration, because RAVEN is both a technical and science demonstrator. Early-stage simulation of RAVEN's performance is critical in establishing that the key science requirement can be met. That is, 30% of the energy of an unresolved pointspread function (PSF) be ensquared within a 140 mas slit using existing WFS camera and deformable mirror (DM) technology. The system was simulated with two independent modeling tools, MAOS and OOMAO, which were in excellent agreement. It was established that RAVEN will be an order 10 × 10 adaptive optics (AO) system by examining the tradeoffs between performance, sky coverage, and WFS field of view. The 30% ensquared-energy (EE) requirement will be met with three NGSs and will exceed 40% if the Subaru Laser Guide Star (LGS) is used onaxis (assuming median image quality). This is also true for NGSs as faint as m R = 14:5. © 2012. The Astronomical Society of the Pacific. All rights reserved.

The Carina project. V. The impact of NLTE effects on the iron content - Fabrizio, M.; Merle, T.; Thévenin, F.; Nonino, M.; Bono, G.; Stetson, P.B.; Ferraro, I.; Iannicola, G.; Monelli, M.; Walker, A.R.; Buonanno, R.; Caputo, F.; et al. (Publications of the Astronomical Society of the Pacific, 2012)
We have performed accurate iron abundance measurements for 44 red giants (RGs) in the Carina dwarf spheroidal (dSph) galaxy. We used archival, high-resolution spectra (R ~ 38, 000) collected with UVES at ESO/VLT either in slit mode (five RGs) or in fiber mode (39 RGs, FLAMES/GIRAFFE-UVES). The sample is more than a factor of 4 larger than any previous spectroscopic investigation of stars in dSphs based on high-resolution (R ≥ 38000) spectra. We did not impose the ionization equilibrium between neutral and singly ionized iron lines. The effective temperatures and the surface gravities were estimated by fitting stellar isochrones in the V, B - V color-magnitude diagram. To measure the iron abundance of individual lines we applied the LTE spectrum-synthesis fitting method using MARCS model atmospheres of appropriate metallicity. For the 27 stars for which we measured both Fe I and Fe II abundances, we found evidence of NLTE effects between neutral and singly ionized iron abundances. The difference is ~0.1 dex, on average, but steadily increases when moving from the metal-rich to the metal-poor regime. Moreover, the two metallicity distributions differ at the 97% confidence level. Assuming that the Fe II abundances are minimally affected by NLTE effects, we corrected the Fe I stellar abundances using a linear fit between Fe I and Fe II stellar abundance determinations. We found that the Carina metallicity distribution based on the corrected Fe I abundances (44 RGs) has a weighted mean metallicity of [Fe/H] = -1.80 and a weighted standard deviation of σ = 0.24 dex. The Carina metallicity distribution based on the Fe II abundances (27 RGs) gives similar estimates ([Fe/H] = -1.72, σ = 0.24 dex). The current weighted mean metallicities are slightly more metal-poor when compared with similar estimates available in the literature. Furthermore, when we restricted our analysis to stars with the most accurate iron abundances, ~20 Fe I and at least three Fe II measurements (15 stars), we found that the range in iron abundances covered by Carina RGs (~1 dex) agreed quite well with similar estimates based on high-resolution spectra; however, it is a factor of 2-3 smaller than abundance estimates based on the near-infrared calcium triplet. This finding supports previous estimates based on photometric metallicity indicators. © 2012. The Astronomical Society of the Pacific. All rights reserved.

InGaN laser diodes operating at 450-460 nm grown by rf-plasma MBE - Skierbiszewski, C.; Siekacz, M.; Turski, H.; Muzioł, G.; Sawicka, M.; Feduniewicz-Zmuda, A.; Smalc-Koziorowska, J.; Perlin, P.; Grzanka, S.; Wasilewski, Z.R.; Kucharski, R.; Porowski, S. (Journal of Vacuum Science and Technology B: Microelectronics and Nanometer Structures, 2012)
This work demonstrates the first true blue laser diodes (LDs) grown by plasma assisted molecular beam epitaxy that operate at the region of 450-460 nm. The single quantum well LDs were grown on several types of c-plane bulk GaN substrates, with threading dislocation densities varying from 10 4 to 10 8cm -2. The key factors that allowed the authors to achieve lasing in true-blue wavelengths are improvements in the growth technology of the InGaN quantum wells attributed to the high nitrogen flux used and the design of the LD structure, which reduced the light losses in the cavity. The authors discuss the influence of the diodes' design on the parameters of LDs. © 2012 American Vacuum Society.
Keywords: Blue laser diodes; GaN substrate; Growth technologies; High-nitrogen; InGaN laser diodes; InGaN quantum wells; Light loss; Plasma assisted molecular beam epitaxy; RF plasma; Single quantum well; Threading dislocation densities; Vacuum applications; Gallium nitride

Search for z ∼ 7 Lyα emitters with the Suprime-Cam at the Subaru telescope - Hibon, P.; Kashikawa, N.; Willott, C.; Iye, M.; Shibuya, T. (The Astrophysical Journal, 2012)
We report a search for z = 7 Lyα emitters (LAEs) using a custom-made narrowband filter centered at 9755 Å with the Suprime-Cam instrument installed at the Subaru telescope. We observed two different fields and obtained two samples of seven LAEs, of which four are robust in each field. We cover the luminosity range of 9.1042-2.1043 erg s-1 in comoving volumes of ∼4 × 105 and 4.3 × 105 Mpc3. From this result, we derived possible z ∼ 7 Lyα luminosity functions for the full samples and for a subsample of four objects in each field. We do not observe, in each case, any strong evolution between the z = 6.5 and z ∼ 7 Lyα luminosity functions. Spectroscopic confirmation for these candidate samples is required to establish a definitive measure of the luminosity function at z ∼ 7. © 2012. The American Astronomical Society. All rights reserved.

Identification and characterization of a lipopolysaccharide α,2,3-sialyltransferase from the human pathogen Helicobacter bizzozeronii - Kondadi, P.K.; Rossi, M.; Twelkmeyer, B.; Schur, M.J.; Li, J.; Schott, T.; Paulin, L.; Auvinen, P.; Hänninen, M.-L.; Schweda, E.K.H.; Wakarchuk, W. (Journal of Bacteriology, 2012)
Terminal sialic acid in the lipopolysaccharides (LPSs) of mucosal pathogens is an important virulence factor. Here we report the characterization of a Helicobacter sialyltransferase involved in the biosynthesis of sialylated LPS in Helicobacter bizzozeronii, the only non-pylori gastric Helicobacter species isolated from humans thus far. Starting from the genome sequences of canine and human strains, we identified potential sialyltransferases downstream of three genes involved in the biosynthesis of N-acetylneuraminic acid. One of these candidates showed monofunctional α,2,3-sialyltransferase activity with a preference for N-acetyllactosamine as a substrate. The LPSs from different strains were shown by SDS-PAGE and high-performance anionexchange chromatography with pulsed amperometric detection (HPAEC-PAD) to contain sialic acid after neuraminidase treatment. The expression of this sialyltransferase and sialyl-LPS appeared to be a phase-variable characteristic common to both human and canine H. bizzozeronii strains. The sialylation site of the LPSs of two H. bizzozeronii strains was determined to be NeuAc-Hex-HexNAc, suggesting terminal 3'-sialyl-LacNAc. Moreover, serological typing revealed the possible presence of sialyl-Lewis X in two additional strains, indicating that H. bizzozeronii could also mimic the surface glycans of mammalian cells. The expression of sialyl-glycans may influence the adaptation process of H. bizzozeronii during the host jump from dogs to humans. © 2012, American Society for Microbiology.
Keywords: alpha, 2,3 sialyltransferase; bacterial enzyme; bacterium lipopolysaccharide; n acetylneuraminic acid; sialic acid; sialidase; sialyl Lewis x antigen; sialyltransferase; unclassified drug; anion exchange chromatography; article; bacterial genome; bacterial strain; bacterium isolate; carbohydrate synthesis; gene sequence; Helicobacter; Helicobacter bizzozeronii; human; nonhuman; nucleotide sequence; polyacrylamide gel electrophoresis; priority journal; protein expression; sialylation; Animals; Antibodies, Bacterial; Cholera Toxin; Dogs; Gene Expression Regulation, Bacterial; Genome, Bacterial; Helicobacter; Humans; Lipopolysaccharides; Molecular Sequence Data; Multigene Family; Phylogeny; Recombinant Proteins; Sialyltransferases; Canis familiaris; Helicobacter; Helicobacter bizzozeronii; Mammalia

Effect of surface modification by ammonia plasma on vascular graft: PET film and PET scaffold - Öteyaka, M.Ö.; Chevallier, P.; Robitaille, L.; Laroche, G. (Acta Physica Polonica A, 2012)
Nowadays, poly (ethylene terephthalate) (PET) textiles, either knitted or woven, are largely used as substitutes for replacement of medium and large calibre (10-40 mm) arteries. Unfortunately, these substitutes do not perform well when they are used to replace small diameter arteries due to thrombogenicity and compliance mismatch issues. Surface treatments were often used as the first step to solve thrombogenicity issues. For example, low pressure ammonia plasma processes can provide modification of the top ≈ 10-50 Å of polymer surface without affecting bulk properties of materials. This work compared ammonia plasma surface modifications of PET film (flat surface) and PET scaffolds (porous surface). Plasma treatments lead to a higher amount of nitrogen as well as amino groups on scaffolds compared to films. N/C maximum was reached for PET film and scaffold after plasma treatments of 5 s and 100 s, respectively. Highest amine concentration on films and scaffolds were obtained at short treatment time, specifically 1 s. In addition, high resolution spectra of C 1s confirmed that amino groups were mainly grafted on aromatic rings. Nodule formation was observed after plasma treatment with atomic force microscopy. Their size and shape increased with longer treatment time.
Keywords: Amino group; Ammonia plasma; Aromatic rings; Bulk properties; Flat surfaces; High-resolution spectra; Low pressure ammonia; PET films; Plasma treatment; Polymer surfaces; Porous surface; Size and shape; Thrombogenicity; Treatment time; Vascular grafts; Ammonia; Atomic force microscopy; Ethylene; Grafting (chemical); Grafts; Materials properties; Plasma applications; Polyethylene terephthalates; Scaffolds (biology); Surface treatment; Weaving; Nitrogen plasma

Flexure mount for a MEMS deformable mirror for the GPI Planet Imager - Hill, A.; Cornelissen, S.; Dillon, D.; Lam, C.; Palmer, D.; Saddlemeyer, L. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
Small deformable mirrors (DMs) produced using microelectromechanical systems (MEMS) techniques have been used in thermally stable, bench-top laboratory environments. With advances in MEMS DM technology, a variety of field applications are becoming more common, such as the Gemini Planet Imager's (GPI) adaptive optics system. Instruments at the Gemini Observatory operate in conditions where fluctuating ambient temperature, varying gravity orientations and humidity and dust can have a significant effect on DM performance. As such, it is crucial that the mechanical design of the MEMS DM mount be tailored to the environment. GPI's approach has been to mount a 4096 actuator MEMS DM, developed by Boston Micromachines Corporation, using high performance optical mounting techniques rather than a typical laboratory set-up. Flexures are incorporated into the DM mount to reduce deformations on the optical surface due to thermal fluctuations. These flexures have also been sized to maintain alignment under varying gravity vector orientations. This paper is a follow-up to a previous paper which presented the preliminary design. The completed design of the opto-mechanical mounting scheme is discussed and results from finite element analysis are presented, including predicting the stability of the mirror surface in varying gravity vectors and thermal conditions. © 2012 SPIE.
Keywords: Adaptive optics systems; Deformable mirrors; Field application; Flexure mounts; Flexures; Gravity vectors; Laboratory environment; Laboratory set-up; Mechanical design; MEMS deformable mirror; MEMS DM; Micromachines; Mirror surfaces; Optical mountings; Optical surfaces; Opto-mechanical mount; Opto-mechanical mounting; Preliminary design; Thermal condition; Thermal fluctuations; Thermally stable; Adaptive optics; Electromechanical devices; Finite element method; Laser pulses; MEMS; Optical telescopes; Telescopes; Mountings

Editorial message: Special track on bioinformatics - Tulpan, D.; Lecca, P.; Jordan, F. (Proceedings of the ACM Symposium on Applied Computing, 2012)

The utility of near infrared imaging in intra-operative prediction of flap outcome: A reverse McFarlane skin flap model study - Sowa, M.G.; Friesen, J.R.; Levasseur, M.; Schattk, B.; Sigurdson, L.; Hayakawa, T. (Journal of Near Infrared Spectroscopy, 2012)
Skin flaps are complex procedures used extensively in reconstructive surgery that require post-operative monitoring to ensure that they do not fail. Near infrared (NIR) spectroscopic imaging is a convenient, non-invasive method for surgeons to examine flaps during surgery and in the early post-operative period. Using a reverse McFarlane skin flap model, we show that model-free chemometric methods as well as simple modified Beer-Lambert analysis of the NIR images provide insights into the blood supply to flaps and demonstrate that the technique can detect and localise perfusion-related complications as well as give real-time feedback to the surgeon as they try to resolve the complication. We also show that using estimates of tissue haemoglobin oxygen saturation, imaging measurements made during surgery and in the early post-operative period are highly predictive of the outcome of the flap tissue with specificities and sensitivities exceeding 85%. © IM Publications LLP 2012. All rights reserved.

Simulation model based approach for long exposure atmospheric point spread function reconstruction for laser guide star multiconjugate adaptive optics - Gilles, L.; Correia, C.; Véran, J.-P.; Wang, L.; Ellerbroek, B. (Applied Optics, 2012)
This paper discusses an innovative simulation model based approach for long exposure atmospheric point spread function (PSF) reconstruction in the context of laser guide star (LGS) multiconjugate adaptive optics (MCAO). The approach is inspired from the classical scheme developed by Véran et al. [J. Opt. Soc. Am. A 14, 3057 (1997)] and Flicker et al. [Astron. Astrophys. 400, 1199 (2003)] and reconstructs the long exposure optical transfer function (OTF), i.e., the Fourier transformed PSF, as a product of separate long-exposure tip/tilt removed and tip/tilt OTFs, each estimated by postprocessing system and simulation telemetry data. Sample enclosed energy results assessing reconstruction accuracy are presented for the Thirty Meter Telescope LGS MCAO system currently under design and show that percent level absolute and differential photometry over a 30 arcsec diameter field of view are achievable provided the simulation model faithfully represents the real system. © 2012 Optical Society of America.
Keywords: Classical schemes; Differential photometry; Field of views; Fourier; Laser guide star; Multiconjugate adaptive optics; Point spread function reconstruction; Post-processing system; Real systems; Reconstruction accuracy; Simulation model; Telemetry data; Thirty Meter Telescope; Adaptive optics; Astrophysics; Lasers; Optical transfer function; Stars; Computer simulation

Structure of the O-antigen polysaccharide present in the lipopolysaccharide of Cronobacter dublinensis (subspecies lactaridi or lausannensis) HPB 3169 - MacLean, L.L.; Vinogradov, E.; Pagotto, F.; Perry, M.B. (Canadian Journal of Microbiology, 2012)
Cronobacter dublinensis (formerly Enterobacter sakazakii) HPB 3169 is a pathogenic Gram-negative bacterium that produces a smooth-type lipopolysaccharide in which the antigenic O-polysaccharide component was determined to be a repeating pentasaccharide unit composed of L-rhamnose; 2-acetamido-2-deoxy-D-glucose; 3,6-dideoxy-3-(R)-3-hydroxybutyramido-Dglucose; and 3-deoxy-manno-oct-2-ulosonic acid in the respective molar ratio 2:1:1:1. Chemical and 2D NMR analyses of the O-polysaccharide and a pentasaccharide derived by the mild acid hydrolysis of the ketosyl linkage of the Kdo (3-deoxy-D-manno-2-octulosonic acid) residue in the O-polysaccharide established that the O-antigen is a high molecular mass unbranched polymer of a repeating pentasaccharide unit and has the structure where Bu is a (R)-3-hydroxybutanoyl substituent. The O-antigen is structurally similar to that of the recently reported Cronobacter sakazakii strain G706 (designated as serotype O5), except that in strain G706 the D-Qui3N is in its N-acetyl form, in contrast to its presence as a 3-deoxy-3-(R)-3-hydroxybutyramido derivative in the C. sakazakii HPB 3169 strain O-antigen.
Keywords: 3 deoxy manno octulosonic acid; 3 hydroxybutyric acid; 3,6 dideoxy 3 3 hydroxybutyramido dextro glucose; bacterium lipopolysaccharide; glucose derivative; n acetylglucosamine; O antigen; pentasaccharide; polymer; rhamnose; unclassified drug; antigen; bacterium; nuclear magnetic resonance; pathogen; polymer; polysaccharide; antigen structure; article; bacterial growth; bacterium isolation; carbohydrate analysis; Cronobacter dublinensis; hydrolysis; molecular weight; nonhuman; nuclear magnetic resonance; peroxidation; priority journal; Acetylglucosamine; Amino Acid Sequence; Carbohydrate Sequence; Cronobacter; Glucose; Hydrolysis; Lipopolysaccharides; Magnetic Resonance Spectroscopy; O Antigens; Oligosaccharides; Bacteria (microorganisms); Enterobacter sakazakii; Negibacteria

Effects of core flow swirl on the flow characteristics of a scalloped forced mixer - Lei, Z.; Mahallati, A.; Cunningham, M.; Germain, P. (Journal of Engineering for Gas Turbines and Power, 2012)
This paper presents a detailed experimental investigation of the influence of core flow swirl on the mixing and performance of a scaled turbofan mixer with 12 scalloped lobes. Measurements were made downstream of the mixer in a coaxial wind tunnel. The core-to-bypass velocity ratio was set to 2:1, temperature ratio to 1.0, and pressure ratio to 1.03, giving a Reynolds number of 5.2×10 5, based on the core flow velocity and equivalent diameter. In the core flow, the background turbulence intensity was raised to 5 and the swirl angle was varied from 0 deg to 30 deg with five vane geometries. At low swirl angles, additional streamwise vortices were generated by the deformation of normal vortices due to the scalloped lobes. With increased core swirl, greater than 10 deg, the additional streamwise vortices were generated mainly due to radial velocity deflection, rather than stretching and deformation of normal vortices. At high swirl angles, stronger streamwise vortices and rapid interaction between various vortices promoted downstream mixing. Mixing was enhanced with minimal pressure and thrust losses for the inlet swirl angles less than 10 deg. However, the reversed flow downstream of the center body was a dominant contributor to the loss of thrust at the maximum core flow swirl angle of 30 deg. © 2012 American Society of Mechanical Engineers.
Keywords: Core flow; Equivalent diameter; Experimental investigations; Flow characteristic; Inlet swirls; Low swirl; Normal vortices; Pressure ratio; Radial velocity; Reversed flow; Streamwise vortices; Swirl angles; Temperature ratio; Thrust loss; Turbulence intensity; Vane geometry; Velocity ratio; Acoustic streaming; Deformation; Mixers (machinery); Mixing; Reynolds number; Vortex flow; Bypass ratio

Physics of lateral triple quantum-dot molecules with controlled electron numbers - Hsieh, C.-Y.; Shim, Y.-P.; Korkusinski, M.; Hawrylak, P. (Reports on Progress in Physics, 2012)
We review the recent progress in theory and experiments with lateral triple quantum dots with controlled electron numbers down to one electron in each dot. The theory covers electronic and spin properties as a function of topology, number of electrons, gate voltage and external magnetic field. The orbital Hund's rules and Nagaoka ferromagnetism, magnetic frustration and chirality, interplay of quantum interference and electron-electron interactions and geometrical phases are described and related to charging and transport spectroscopy. Fabrication techniques and recent experiments are covered, as well as potential applications of triple quantum-dot molecule in coherent control, spin manipulation and quantum computation. © 2012 IOP Publishing Ltd.

An inexpensive liquid crystal spectropolarimeter for the dominion astrophysical observatory plaskett telescope - Monin, D.; Bohlender, D.; Hardy, T.; Saddlemyer, L.; Fletcher, M. (Publications of the Astronomical Society of the Pacific, 2012)
A new, inexpensive polarimetric unit has been constructed for the Dominion Astrophysical Observatory (DAO) 1.8 m Plaskett telescope. It is implemented as a plug-in module for the telescope's existing Cassegrain spectrograph, and it enables medium-resolution (R≈10,000) circular spectropolarimetry of point sources. A dual-beam design, together with fast switching of the wave plate at rates up to 100 Hz and synchronized with charge shuffling on the CCD, is used to significantly reduce instrumental effects and achieve high-precision spectropolarimetric measurements for a very low cost. The instrument is optimized to work in the wavelength range of 4700-5300 Å to simultaneously detect polarization signals in the Hβ line, as well as nearby metallic lines. In this article we describe the technical details of the instrument, our observing strategy, and data reduction techniques, and we present tests of its scientific performance. © 2012. The Astronomical Society of the Pacific.

RILEM TC 203-RHM: Repair mortars for historic masonry: Ments for repointing mortars for historic masonry - Maurenbrecher, P. (Materials and Structures/Materiaux et Constructions, 2012)
This paper gives a summary of functional and performance requirements for repointing mortars for historic masonry (design, execution and maintenance). Successful performance of repair and conservation of mortar in historic masonry requires more care with design and execution than with modern masonry. © 2012 RILEM.
Keywords: Historic masonry; Masonry; Performance requirements; Repointing; Conservation; Repair; Mortar

Self-priming of liquids in capillary autonomous microfluidic systems - Clime, L.; Brassard, D.; Pezacki, J.P.; Veres, T. (Microfluidics and Nanofluidics, 2012)
We present a numerical approach to the capillary rise dynamics in microfluidic channels of complex 3D geometries. In order to optimize the delivery of specific biological fluids to target regions in microfluidic capillary autonomous systems (CAS), we analyze self-priming of liquid water into a microfluidic device consisting of a microfluidic channel that feeds a rectangular microfluidic cavity trough an appropriately designed micro-chamber. The target performance criteria in our optimization are (1) fast and complete wetting of the cavity bottom while (2) minimizing the probability of trapping air bubble in the device. The numerical model is based on the lattice Boltzmann method (LBM) and a three-dimensional single-component multiple-phase (SCMP) scheme. By using a parallel implementation of this algorithm, we investigate the physical processes related to the invasion of the liquid-gas interfaces in rectangular cavities at different liquid-solid contact angle and shapes of the transition micro-chamber. The numerical results has successfully captured important qualitative and some key quantitative effects of the liquid-solid contact angle, the roughness of the cavity edges, the depth of the holes and shape of the micro-chambers. Moreover, we present and validate experimentally simple geometrical optimizations of the microfluidic device that ensure the complete filling the microfluidic cavity with liquid. Critical parameters related to the overall priming time of the device are presented as well. © 2011 Crown Copyright as represented by the National Research Council.
Keywords: 3-D microfluidic; Air bubbles; Autonomous systems; Biological fluids; Capillary rise; Complete wetting; Complex 3D geometry; Contact line dynamics; Critical parameter; Geometrical optimization; Lattice Boltzmann method; Liquid gas interface; Liquid solids; Liquid water; Micro fluidic system; Micro-chambers; Micro-fluidic devices; Microfluidic cavity; Microfluidic channel; Numerical approaches; Numerical models; Numerical results; Parallel implementations; Performance criterion; Physical process; Quantitative effects; Rectangular cavity; Self-priming; Target regions; Capillary flow; Contact angle; Dynamics; Fluidic devices; Liquids; Numerical methods; Optimization; Phase interfaces; Three dimensional; Wetting; Microfluidics

Role of macrophages in early host resistance to respiratory Acinetobacter baumannii infection - Qiu, H.; KuoLee, R; Harris, G; Van Rooijen, N; Patel, G.B; Chen, W (PloS one, 2012)
Acinetobacter baumannii is an emerging bacterial pathogen that causes nosocomial pneumonia and other infections. Although it is recognized as an increasing threat to immunocompromised patients, the mechanism of host defense against A. baumannii infection remains poorly understood. In this study, we examined the potential role of macrophages in host defense against A. baumannii infection using in vitro macrophage culture and the mouse model of intranasal (i.n.) infection. Large numbers of A. baumannii were taken up by alveolar macrophages in vivo as early as 4 h after i.n. inoculation. By 24 h, the infection induced significant recruitment and activation (enhanced expression of CD80, CD86 and MHC-II) of macrophages into bronchoalveolar spaces. In vitro cell culture studies showed that A. baumannii were phagocytosed by J774A.1 (J774) macrophage-like cells within 10 minutes of co-incubation, and this uptake was microfilament- and microtubule-dependent. Moreover, the viability of phagocytosed bacteria dropped significantly between 24 and 48 h after co-incubation. Infection of J774 cells by A. baumannii resulted in the production of large amounts of proinflammatory cytokines and chemokines, and moderate amounts of nitric oxide (NO). Prior treatment of J774 cells with NO inhibitors significantly suppressed their bactericidal efficacy (P<0.05). Most importantly, in vivo depletion of alveolar macrophages significantly enhanced the susceptibility of mice to i.n. A. baumannii challenge (P<0.01). These results indicate that macrophages may play an important role in early host defense against A. baumannii infection through the efficient phagocytosis and killing of A. baumannii to limit initial pathogen replication and the secretion of proinflammatory cytokines and chemokines for the rapid recruitment of other innate immune cells such as neutrophils.
Keywords: Macrophages; Bacterial pathogens; Respiratory infections; Neutrophils; Alveolar macrophages; Cytokines; Nitric oxide; Phagocytosis

Helicobacter pylori isolates from Greek children express type 2 and type 1 Lewis and α1, 6-glucan antigens in conjunction with a functional type IV secretion system - Altman, E.; Chandan, V.; Harrison, B.A.; Panayotopoulou, E.G.; Roma-Giannikou, E.; Li, J.; Sgouras, D.N. (Journal of Medical Microbiology, 2012)
Helicobacter pylori infection is often acquired in childhood and can persist for life. Previous studies in adult patients have shown that H. pylori isolates from North American and European hosts express predominantly type 2 Lewis x (Le x) and Le y epitopes, while Asian strains have the capacity to express type 1 Le a and Le b structures. In order to understand the influence of environmental and host factors on the expression of Le antigens, we analysed 50 Greek H. pylori isolates from symptomatic children. Both CagA-positive and-negative strains were evaluated. The expression of Le antigens was determined by whole-cell indirect ELISA (WCE), and LPS profiles were assessed by gel electrophoresis and immunoblotting. Occurrence of Le x and/or Ley antigens was confirmed in 35 of the isolates (70 %) while 15 of the isolates were non-typable. It was found that 11 of the paediatric isolates had the propensity to express type 1 Le b blood-group antigen (22 %), a feature relatively uncommon in H. pylori isolates from adults. One strain expressed both Le b and Le a antigens. The majority of the isolates (49/50, 98 %) expressed α1,6-glucan, an antigenic non-Le determinant present in the outer core region of H. pylori LPS. All Le x-and Leyexpressing strains also carried a functional cag pathogenicity island-encoding a type IV secretion system, capable of translocating CagA protein, as well as the vacAs1 allele, suggesting that Le x and Ley epitopes may aid the persistence of more aggressive strains. No association between bacterial virulence characteristics and the histopathological observations was evident. © 2012 National Research Council of Canada.
Keywords: alpha1,6 glucan antigen; CagA protein; epitope; glucan; unclassified drug; adolescent; article; bacterial strain; bacterium isolate; child; enzyme linked immunosorbent assay; gel electrophoresis; Greece; Helicobacter infection; Helicobacter pylori; human; human tissue; immunoblotting; nonhuman; pathogenicity; pediatrics; preschool child; priority journal; school child; Adolescent; Antigens, Bacterial; Bacterial Proteins; Child; Child, Preschool; Gastric Mucosa; Gene Expression Regulation, Bacterial; Glucans; Greece; Helicobacter Infections; Helicobacter pylori; Humans; Lewis Blood-Group System

Clustering properties of BzK-selected galaxies in goods-N: Environmental quenching and triggering of star formation at z 2 - Lin, L.; Dickinson, M.; Jian, H.-Y.; Merson, A.I.; Baugh, C.M.; Scott, D.; Foucaud, S.; Wang, W.-H.; Yan, C.-H.; Yan, H.-J.; Cheng, Y.-W.; Guo, Y.; et al. (The Astrophysical Journal, 2012)
Using a sample of BzK-selected galaxies at z ∼ 2 identified from the CFHT/WIRCAM near-infrared survey of GOODS-North, we discuss the relation between star formation rate (SFR), specific star formation rate (SSFR), and stellar mass (M *), and the clustering of galaxies as a function of these parameters. For star-forming galaxies (sBzKs), the UV-based SFR, corrected for extinction, scales with the stellar mass as SFRM α * with α = 0.74 ± 0.20 down to M * 10 9 M ⊙, indicating a weak dependence on the stellar mass of the SFR efficiency, namely, SSFR. We also measure the angular correlation function and hence infer the correlation length for sBzK galaxies as a function of M *, SFR, and SSFR, as well as K-band apparent magnitude. We show that passive galaxies (pBzKs) are more strongly clustered than sBzK galaxies at a given stellar mass, mirroring the color-density relation seen at lower redshifts. We also find that the correlation length of sBzK galaxies ranges from 4 to 20h -1Mpc, being a strong function of M K , M *, and SFR. On the other hand, the clustering dependence on SSFR changes abruptly at 2 × 10 -9yr -1, which is the typical value for "main-sequence" star-forming galaxies at z ∼ 2. We show that the correlation length reaches a minimum at this characteristic value, and is larger for galaxies with both smaller and larger SSFRs; a dichotomy that is only marginally implied from the predictions of the semi-analytical models. Our results suggest that there are two types of environmental effects at work at z ∼ 2. Stronger clustering for relatively quiescent galaxies implies that the environment has started to play a role in quenching star formation. At the same time, stronger clustering for galaxies with elevated SSFRs (" starbursts") might be attributed to an increased efficiency for galaxy interactions and mergers in dense environments. © © 2012. The American Astronomical Society. All rights reserved.

Third component search and abundances of the very dusty short-period binary BD +20°307 - Fekel, F.C.; Cordero, M.J.; Galicher, R.; Zuckerman, B.; Melis, C.; Weinberger, A.J. (The Astrophysical Journal, 2012)
We have obtained near-infrared adaptive optics imaging and collected additional radial velocity observations to search for a third component in the extremely dusty short-period binary system BD +20°307. Our image shows no evidence for a third component at separations greater than 19AU. Our four seasons of radial velocities have a constant center-of-mass velocity and are consistent with the systemic velocities determined at two earlier epochs. Thus, the radial velocities also provide no support for a third component. Unfortunately, the separation domains covered by our imaging and radial velocity results do not overlap. Thus, we examined the parameters for possible orbits of a third component that could have been missed by our current observations. With our velocities we determined improved circular orbital elements for the 3.4 day double-lined binary. We also performed a spectroscopic abundance analysis of the short-period binary components and conclude that the stars are a mid- and a late-F dwarf. We find that the iron abundances of both components, [Fe/H] = 0.15, are somewhat greater than the solar value and comparable to that of stars in the Hyades. Despite the similarity of the binary components, the lithium abundances of the two stars are very unequal. The primary has log ε (Li) = 2.72, while in the secondary log ε (Li)≤1.46, which corresponds to a difference of at least a factor of 18. The very disparate lithium abundances in very similar stars make it impossible to ascribe a single age to them. While the system is likely at least 1Gyr old, it may well be as old as the Sun. © 2012 The American Astronomical Society. All rights reserved.

Tribological behaviors of titanium nitride-and chromium-nitride-based physical vapor deposition coating systems - Cai, F.; Huang, X.; Yang, Q.; Nagy, D. (Journal of Engineering for Gas Turbines and Power, 2012)
This study investigates the effects of the deposition process and coating composition on microstructural and tribological properties of TiN-and CrN-based coating systems. Coatings were produced using various PVD-based processes-electron beam (EB), cathodic arc (CA), and plasma enhanced magnetron sputtering (PEMS). All coated samples were evaluated for their composition, microstructure, and surface morphology. Coating mechanical properties such as hardness, Young's modulus, and coefficient of friction were also studied and related to their microstructures, wear, and erosion resistances. It was found that hardness (H), Young's modulus (E), and coefficient of friction had impact on both wear and erosion rates. In particular, the H 3/E 2 ratio was inversely proportional to the specific wear rate. For erosion behavior, higher H 3/E 2 ratios relate to lower erosion rates at low impingement angles, whereas higher H 3/E 2 ratios relate to higher erosion rates at high impingement angles. © 2012 American Society of Mechanical Engineers.
Keywords: Cathodic arc; Coated sample; Coating compositions; Coefficient of frictions; CrN-based coatings; Deposition process; Erosion behavior; Erosion rates; Erosion resistance; Impingement angle; Micro-structural; Physical vapor deposition coatings; Plasma enhanced magnetron sputtering; Tribological behaviors; Tribological properties; Wear rates; Young's Modulus; Amorphous films; Chromium; Elastic moduli; Electron beams; Friction; Hardness; Microstructure; Protective coatings; Titanium nitride; Tribology; Erosion

Dilution effects on partially-premixed combustion of an ultra-low sulphur diesel fuel under low-load operation - Dumitrescu, C.E.; Neill, W.S.; Guo, H.; Chippior, W.L. (Proceedings of the Spring Technical Conference of the ASME Internal Combustion Engine Division, 2012)
Dilution of partially-premixed combustion (PPC) using different combinations of excess air (λ>1) and exhaust gas recirculation (EGR) was investigated in a single-cylinder, heavy-duty diesel engine equipped with common-rail fuel injection. The experiments were limited to a single fuel injection event using ultra-low sulphur diesel fuel at a low engine load (∼3 bar BMEP) and engine speeds of 900 and 1350 rpm. The start of injection was varied to optimize the combustion performance and emissions. The experimental results show that increasing air dilution at constant EGR reduced BSFC slightly. CO and HC emissions decreased significantly due to the increased oxygen concentration, but NOx and soot emissions increased. For a given level of charge dilution, there was an optimal EGR rate to minimize BSFC. NOx emissions decreased significantly as the proportion of dilution by EGR was increased, but CO and HC emissions increased due to the reduced in-cylinder temperature and oxygen concentration, which increased the combustion duration. Copyright © 2012 by Her Majesty the Queen in Right of Canada.
Keywords: Charge dilution; Combustion duration; Combustion performance; Exhaust gas recirculation (EGR); Heavy-duty diesel engine; Oxygen concentrations; Partially-premixed; Start of injections; Combustion; Diesel engines; Diesel fuels; Fuel injection; Optimization; Oxygen; Sulfur; Dilution

The ACS LCIS project. VII. the blue stragglers population in the isolated dSph galaxies Cetus and Tucana - Monelli, M.; Cassisi, S.; Mapelli, M.; Bernard, E.J.; Aparicio, A.; Skillman, E.D.; Stetson, P.B.; Gallart, C.; Hidalgo, S.L.; Mayer, L.; Tolstoy, E. (The Astrophysical Journal, 2012)
We present the first investigation of the Blue Straggler star (BSS) population in two isolated dwarf spheroidal galaxies of the Local Group, Cetus and Tucana. Deep Hubble Space Telescope/Advanced Camera for Surveys photometry allowed us to identify samples of 940 and 1214 candidates, respectively. The analysis of the star formation histories of the two galaxies suggests that both host a population of BSSs. Specifically, if the BSS candidates are interpreted as young main sequence stars, they do not conform to their galaxy's age-metallicity relationship. The analysis of the luminosity function and the radial distributions supports this conclusion, and suggests a non-collisional mechanism for the BSS formation, from the evolution of primordial binaries. This scenario is also supported by the results of new dynamical simulations presented here. Both galaxies coincide with the relationship between the BSS frequency and the absolute visual magnitude MV found by Momany etal. If this relationship is confirmed by larger sample, then it could be a valuable tool to discriminate between the presence of BSSs and galaxies hosting truly young populations. © 2012 The American Astronomical Society. All rights reserved.

Early-type galaxies at z ∼ 1.3. IV. Scaling relations in different environments - Raichoor, A.; Mei, S.; Stanford, S.A.; Holden, B.P.; Nakata, F.; Rosati, P.; Shankar, F.; Tanaka, M.; Ford, H.; Huertas-Company, M.; Illingworth, G.; Kodama, T.; et al. (The Astrophysical Journal, 2012)
We present the Kormendy and mass-size relations (MSR) for early-type galaxies (ETGs) as a function of environment at z ∼ 1.3. Our sample includes 76 visually classified ETGs with masses 10 10 < M/M Ȯ < 10 11.5, selected in the Lynx supercluster and in the Great Observatories Origins Deep Survey/Chandra Deep Field South field; 31 ETGs in clusters, 18 in groups, and 27 in the field, all with multi-wavelength photometry and Hubble Space Telescope/Advanced Camera for Surveys observations. The Kormendy relation, in place at z 1.3, does not depend on the environment. The MSR reveals that ETGs overall appear to be more compact in denser environments: cluster ETGs have sizes on average around 30%-50% smaller than those of the local universe and a distribution with a smaller scatter, whereas field ETGs show an MSR with a similar distribution to the local one. Our results imply that (1) the MSR in the field did not evolve overall from z ∼ 1.3 to present; this is interesting and in contrast to the trend found at higher masses from previous works; (2) in denser environments, either ETGs have increased in size by 30%-50% on average and spread their distributions, or more ETGs have been formed within the dense environment from non-ETG progenitors, or larger galaxies have been accreted to a pristine compact population to reproduce the MSR observed in the local universe. Our results are driven by galaxies with masses M ≲ 2 × 10 11 M Ȯ and those with masses M ∼ 10 11 M Ȯ follow the same trends as that of the entire sample. Following the Valentinuzzi et al. definition of superdense ETGs, ∼ 35%-45% of our cluster sample is made up of superdense ETGs. © 2012. The American Astronomical Society. All rights reserved.

Molecular line contamination in the SCUBA-2 450 and 850 μm continuum data - Drabek, E.; Hatchell, J.; Friberg, P.; Richer, J.; Graves, S.; Buckle, J.V.; Nutter, D.; Johnstone, D.; Di Francesco, J. (Monthly Notices of the Royal Astronomical Society, 2012)
Observations of the dust emission using millimetre/submillimetre bolometer arrays can be contaminated by molecular line flux, such as flux from 12CO. As the brightest molecular line in the submillimetre, it is important to quantify the contribution of CO flux to the dust continuum bands. Conversion factors were used to convert molecular line integrated intensities to flux detected by bolometer arrays in mJybeam -1. These factors were calculated for 12CO line integrated intensities to the SCUBA-2 850 and 450μm bands. The conversion factors were then applied to HARP 12CO 3-2 maps of NGC 1333 in the Perseus complex and NGC 2071 and NGC 2024 in the Orion B molecular cloud complex to quantify the respective 12CO flux contribution to the 850μm dust continuum emission. Sources with high molecular line contamination were analysed in further detail for molecular outflows and heating by nearby stars to determine the cause of the 12CO contribution. The majority of sources had a 12CO 3-2 flux contribution under 20per cent. However, in regions of molecular outflows, the 12CO can dominate the source dust continuum (up to 79per cent contamination) with 12CO fluxes reaching ∼68mJybeam -1. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Doubled haploidy as a tool in ornamental breeding - Ferrie, A.M.R. (Acta Horticulturae, 2012)
Haploidy/doubled haploidy methodology is commonly used in many agronomically important crops to speed the development of new cultivars. There are a number of advantages in using haploidy technology in both practical application (varietal development, mutagenesis, transformation) and basic research (genomics, biochemical, and physiological studies). Haploid plants are commonly produced using one of four methods: culture of anthers or microspores (androgenesis), culture of unfertilized ovules (gynogenesis), interspecific or intergeneric crosses followed by chromosome elimination, and by pollination with irradiated pollen. The most efficient method depends on the species. In many species, the culture of isolated microspores or anthers is the most frequently used method of haploid production. With this method, every microspore is potentially capable of regenerating into a viable embryo and each plant would therefore represent the variation which exists in the population of microspores. Plant regeneration occurs either by direct embryogenesis or through callus formation followed by embryogenesis or organogenesis. There are a number of factors influencing embryogenesis from anther/microspores or ovaries/ovules including genotype, donor plant growth conditions, stage of explant development, composition of the culture medium, and environmental conditions during culture. The frequency of embryo production will depend on whether or not these conditions are optimal and varies depending on the species. Compared to some agronomic species, there has been very little work on doubled haploidy in ornamental species despite the potential benefits.

Instantaneous spectroscopic SS-OCT imaging using a simultaneous dual-band swept laser and common-path fiber probe - Mao, Y.; Chang, S.; Flueraru, C.; Murdock, E. (SPIE - International Society for Optical Engineering. Proceedings, 2012)
A simultaneous 1310/1550 swept-source optical coherence tomography system is implemented by combining a novel dual-band swept laser source and an integrated common-path GRIN lensed fiber interferometer/probe. Highspeed synchronized dual-wavelength tuning is performed by using two laser cavities with a single dual-window polygonal. Simultaneous in vivo OCT imaging at 1310 and 1550 nm is demonstrated. This dual-band technique bring together common-path fiber probe potentially allows instantaneous in situ functional OCT imaging with high quality spectroscopic contrast and stable phase measurements. © 2012 SPIE.
Keywords: Common-path interferometers; Dual-window polygonal; Fiber probe; Grin fibers; Spectroscopic contrast; Swept source; Swept source optical coherence tomographies; Fibers; Probes; Optical tomography

Load monitoring of aerospace structures utilizing micro-electro-mechanical systems for static and quasi-static loading conditions - Martinez, M.; Rocha, B.; Li, M.; Shi, G.; Beltempo, A.; Rutledge, R.; Yanishevsky, M. (Smart Materials and Structures, 2012)
The National Research Council Canada (NRC) has worked on the development of structural health monitoring (SHM) test platforms for assessing the performance of sensor systems for load monitoring applications. The first SHM platform consists of a 5.5m cantilever aluminum beam that provides an optimal scenario for evaluating the ability of a load monitoring system to measure bending, torsion and shear loads. The second SHM platform contains an added level of structural complexity, by consisting of aluminum skins with bonded/riveted stringers, typical of an aircraft lower wing structure. These two load monitoring platforms are well characterized and documented, providing loading conditions similar to those encountered during service. In this study, a micro-electro-mechanical system (MEMS) for acquiring data from triads of gyroscopes, accelerometers and magnetometers is described. The system was used to compute changes in angles at discrete stations along the platforms. The angles obtained from the MEMS were used to compute a second, third or fourth order degree polynomial surface from which displacements at every point could be computed. The use of a new Kalman filter was evaluated for angle estimation, from which displacements in the structure were computed. The outputs of the newly developed algorithms were then compared to the displacements obtained from the linear variable displacement transducers connected to the platforms. The displacement curves were subsequently post-processed either analytically, or with the help of a finite element model of the structure, to estimate strains and loads. The estimated strains were compared with baseline strain gauge instrumentation installed on the platforms. This new approach for load monitoring was able to provide accurate estimates of applied strains and shear loads. © 2012 IOP Publishing Ltd.
Keywords: Aerospace structure; Aluminum beams; Aluminum skin; Angle estimation; Applied strain; Displacement curve; Finite element models; Fourth order; Linear variable displacement transducers; Load monitoring; Load monitoring systems; Loading condition; Micro electro mechanical system; National Research Council; Polynomial surface; Quasi-static loading; Sensor systems; Shear loads; Structural complexity; Test platforms; Wing structures; Aluminum; Estimation; Finite element method; MEMS; Stringers; Transducers; Loading

Collisional evolution of ultra-wide trans-neptunian binaries - Parker, A.H.; Kavelaars, J.J. (The Astrophysical Journal, 2012)
The widely separated, near-equal mass binaries hosted by the cold classical Kuiper Belt are delicately bound and subject to disruption by many perturbing processes. We use analytical arguments and numerical simulations to determine their collisional lifetimes given various impactor size distributions and include the effects of mass loss and multiple impacts over the lifetime of each system. These collisional lifetimes constrain the population of small (R ≳ 1km) objects currently residing in the Kuiper Belt and confirm that the size distribution slope at small size cannot be excessively steep - likely q ≲ 3.5. We track mutual semimajor axis, inclination, and eccentricity evolution through our simulations and show that it is unlikely that the wide binary population represents an evolved tail of the primordially tight binary population. We find that if the wide binaries are a collisionally eroded population, their primordial mutual orbit planes must have preferred to lie in the plane of the solar system. Finally, we find that current limits on the size distribution at small radii remain high enough that the prospect of detecting dust-producing collisions in real time in the Kuiper Belt with future optical surveys is feasible. © 2012. The American Astronomical Society. All rights reserved.

Comparison of experimental and numerical results for the quasi-static and dynamic tensile behaviour of a commercial Ti6Al4V alloy as a function of initial crystallographic texture - Coghe, F.; Tirry, W.; Peirs, J.; Verleysen, P.; Dalgaard, E.; Wanjara, P.; Rabet, L.; Van Houtte, P. (Materials Science Forum, 2012)
Quasi-static tensile tests and high strain rate split Hopkinson bar tensile experiments were used to mechanically characterize a commercially available Ti6Al4V alloy. The material was tested along different directions as to assess the influence of the initial crystallographic texture on the mechanical behaviour. In order to circumvent the problem of the limited thickness of the base material, special usage was made of the Linear Friction Welding technique. The results of the experiments were afterwards compared to the numerical results of a crystal plasticity code based on the viscoplastic self-consistent approach, taking into account twinning as an active deformation mode. © 2012 Trans Tech Publications, Switzerland.
Keywords: Active deformation; Base material; Crystal plasticity; Crystallographic textures; High strain rates; Linear friction welding; Mechanical behaviour; Numerical results; Quasi-static; Quasi-static tensile test; SHPB; Split Hopkinson bar; Tensile behaviour; Ti-6al-4v; Ti-6Al-4V alloy; Visco-plastic self-consistent; VPSC; Bars (metal); Strain rate; Tensile testing; Textures; Titanium; Twinning; Experiments; Experiments; Twinning

Shape from suggestive contours using 3D priors - Wuhrer, Stefanie; Shu, Chang (2012 Ninth Conference on Computer and Robot Vision (CRV), 2012)
This paper introduces an approach to predict the three-dimensional shape of an object belonging to a specific class of shapes shown in an input image. We use suggestive contour, a shape-suggesting image feature developed in computer graphics in the context of non-photorealistic rendering, to reconstruct 3D shapes. We learn a functional mapping from the shape space of suggestive contours to the space of 3D shapes and use this mapping to predict 3D shapes based on a single input image. We demonstrate that the method can be used to predict the shape of deformable objects and to predict the shape of human faces using synthetic experiments and experiments based on artist drawn sketches and photographs.
Keywords: Deformable object; Functional mapping; Non-Photorealistic Rendering; Shape inference; statistical priors; suggestive contours; Synthetic experiments; Three-dimensional shape; Computer graphics; Drawing (graphics); Experiments; Forecasting; Photography; Computer vision

Effect of n-CaCO 3 and metakaolin on hydrated Portland cement - Makar, J.M.; Beaudoin, J.J.; Trischuk, K.; Chan, G.W.; Torres, F. (Advances in Cement Research, 2012)
The effect of calcium carbonate nanoparticles (nCaCO 3) on the hydration of ordinary Portland cement (OPC) blended with metakaolin was studied through comparison with OPC, OPC plus metakaolin and OPC plus nCaCO 3 control samples. Isothermal conduction calorimetry measurements showed that the hydration of the ternary OPC-metakaolin-nCaCO 3 blend had pronounced early secondary phase hydration activity compared to the controls. X-ray diffraction and thermogravimetric analysis identified the phases as calcium aluminosulfates, with both ettringite and monosulfate forming more quickly in the ternary blend than in the other samples. The presence of the nCaCO 3 also enhanced the formation of C 3A. CaCO 3. 12H 2O in both blends that contained it. The presence of the secondary phases or the nCaCO 3 itself was associated with a significant reduction in strength in the ternary blend as compared to the OPC-metakaolin binary blend. The results suggest that caution is needed in the development of concrete with nanoparticle additions in order to avoid detrimental combinations of nanoparticles, OPC and supplementary cementing materials. © 2012 Thomas Telford Ltd.
Keywords: Binary blends; Control samples; Ettringites; Hydration activity; Isothermal conduction calorimetries; Metakaolins; Nanoparticle addition; Ordinary Portland cement; Secondary phase; Secondary phasis; Supplementary cementing materials; Ternary blends; Calcium carbonate; Nanoparticles; Portland cement; Thermogravimetric analysis; X ray diffraction; Hydration

Lack of functional selectin ligand interactions compromises long term tumor protection by CD8 + T cells - Stark, F.C.; Gurnani, K.; Sad, S.; Krishnan, L. (PLoS ONE, 2012)
Central memory CD8 + T cells expressing the adhesion molecule CD62L (L-selectin) are potent mediators of anti-cancer immunity due to their ability to proliferate extensively upon antigen re-stimulation. The interaction of selectin with its ligands mediates leukocyte rolling along high endothelial venules. Mice deficient in α(1,3) Fucosyltransferase IV and VII (FtDKO) lack functional L, P and E selectin ligands. Thus, we addressed whether the lack of selectin ligand interactions alters tumor protection by CD8 + T cells in FtDKO mice. Listeria monocytogenes-OVA (LM-OVA) infection evoked potent OVA-specific CD8 + T cells that proliferated and contracted at similar kinetics and phenotype in FtDKO and wild-type mice. Additionally, OVA-specific CD8 + T cells in both mouse strains exhibited similar phenotypic differentiation, in vivo cytolytic activity and IFN-γ expression. However, FtDKO mice succumbed to B16-OVA tumors significantly earlier than wild-type mice. In contrast, FtDKO mice evoked strong recall memory CD8 + T cell responses and protection to systemic LM-OVA re-challenge. The diminished tumor protection in FtDKO mice was not related to defective antigen presentation by dendritic cells or reduced proliferation of antigen-specific CD8 + T cells. However, WT or FtDKO OVA-specific CD8 + T cells showed significantly reduced ability to traffic to lymph nodes upon adoptive transfer into naïve FtDKO recipients. Furthermore, FtDKO OVA-specific CD8 + T cells displayed poor ability to infiltrate tumors growing in WT mice. These results reveal that selectin ligand expression on host endothelium as well CD8 + T cells may be important for their efficient and continued extravasation into peripheral tumors. © 2012 Stark et al.
Keywords: bacterial vaccine; gamma interferon; selectin; tumor antigen; fucosyltransferase; ligand; ovalbumin; selectin; animal cell; animal experiment; animal model; article; cancer prevention; CD8+ T lymphocyte; cell infiltration; cell migration; cell proliferation; cellular immunity; controlled study; dendritic cell; in vivo study; Listeria monocytogenes; lymphocyte function; mouse; nonhuman; phenotype; protein determination; protein expression; protein function; protein localization; protein protein interaction; tumor growth; tumor immunity; tumor xenograft; wild type; animal; antigen presentation; immunology; mouse mutant; neoplasm; Animals; Antigen Presentation; CD8-Positive T-Lymphocytes; Fucosyltransferases; Ligands; Mice; Mice, Knockout; Neoplasms; Ovalbumin; Selectins

Globular cluster systems of early-type galaxies in low-density environments - Cho, J.; Sharples, R.M.; Blakeslee, J.P.; Zepf, S.E.; Kundu, A.; Kim, H.-S.; Yoon, S.-J. (Monthly Notices of the Royal Astronomical Society, 2012)
Deep images of 10 early-type galaxies in low-density environments have been obtained with the Advanced Camera for Surveys (ACS) aboard the Hubble Space Telescope. The global properties of the globular cluster (GC) systems of the galaxies have been derived in order to investigate the role of the environment in galaxy formation and evolution. Using the ACS Virgo Cluster Survey as a high-density counterpart, the similarities and differences between the GC properties in high- and low-density environments are presented. We find a strong correlation of the GC mean colours and the degree of colour bimodality with the host galaxy luminosity in low-density environments, in good agreement with high-density environments. In contrast, the GC mean colours at a given host luminosity are somewhat bluer [Δ(g-z) ∼ 0.05] than those for cluster galaxies, indicating more metal poor (Δ[Fe/H] ∼ 0.10 - 0.15) and/or younger (Δage > 2 Gyr) GC systems than those in dense environments. Furthermore, with decreasing host luminosity, the colour bimodality disappears faster, when compared to galaxies in cluster environments. Our results suggest that: (1) in both high- and low-density environments, the mass of the host galaxy has the dominant effect on GC system properties; (2) the local environment has only a secondary effect on the history of GC system formation; and (3) GC formation must be governed by common physical processes across a range of environments. © 2012 The Authors Monthly Notices of the Royal Astronomical Society © 2012 RAS.

Multiple stellar populations in 47 Tucanae - Milone, A.P.; Piotto, G.; Bedin, L.R.; King, I.R.; Anderson, J.; Marino, A.F.; Bellini, A.; Gratton, R.; Renzini, A.; Stetson, P.B.; Cassisi, S.; Aparicio, A.; et al. (The Astrophysical Journal, 2012)
We use Hubble Space Telescope (HST) and ground-based imaging to study the multiple populations of 47 Tucanae (47 Tuc), combining high-precision photometry with calculations of synthetic spectra. Using filters covering a wide range of wavelengths, our HST photometry splits the main sequence into two branches, and we find that this duality is repeated in the subgiant and red giant regions, and on the horizontal branch. We calculate theoretical stellar atmospheres for main-sequence stars, assuming different chemical composition mixtures, and we compare their predicted colors through the HST filters with our observed colors. We find that we can match the complex of observed colors with a pair of populations, one with primeval abundance and another with enhanced nitrogen and a small helium enhancement, but with depleted C and O. We confirm that models of red giant and red horizontal branch stars with that pair of compositions also give colors that fit our observations. We suggest that the different strengths of molecular bands of OH, CN, CH, and NH, falling in different photometric bands, are responsible for the color splits of the two populations. Near the cluster center, in each portion of the color-magnitude diagram the population with primeval abundances makes up only ∼20% of the stars, a fraction that increases outward, approaching equality in the outskirts of the cluster, with a fraction ∼30% averaged over the whole cluster. Thus the second, He/N-enriched population is more concentrated and contributes the majority of the present-day stellar content of the cluster. We present evidence that the color-magnitude diagram of 47 Tuc consists of intertwined sequences of the two populations, whose separate identities can be followed continuously from the main sequence up to the red giant branch, and thence to the horizontal branch. A third population is visible only in the subgiant branch, where it includes ∼8% of the stars.

Two methodologies for optical analysis of contaminated engine lubricants - Aghayan, H.; Bordatchev, E.; Yang, J. (Measurement Science and Technology, 2012)
The performance, efficiency and lifetime of modern combustion engines significantly depend on the quality of the engine lubricants. However, contaminants, such as gasoline, moisture, coolant and wear particles, reduce the life of engine mechanical components and lubricant quality. Therefore, direct and indirect measurements of engine lubricant properties, such as physical-mechanical, electro-magnetic, chemical and optical properties, are intensively utilized in engine condition monitoring systems and sensors developed within the last decade. Such sensors for the measurement of engine lubricant properties can be used to detect a functional limit of the in-use lubricant, increase drain interval and reduce the environmental impact. This paper proposes two new methodologies for the quantitative and qualitative analysis of the presence of contaminants in the engine lubricants. The methodologies are based on optical analysis of the distortion effect when an object image is obtained through a thin random optical medium (e.g. engine lubricant). The novelty of the proposed methodologies is in the introduction of an object with a known periodic shape behind a thin film of the contaminated lubricant. In this case, an acquired image represents a combined lubricant-object optical appearance, where an a priori known periodic structure of the object is distorted by a contaminated lubricant. In the object shape-based optical analysis, several parameters of an acquired optical image, such as the gray scale intensity of lubricant and object, shape width at object and lubricant levels, object relative intensity and width non-uniformity coefficient are newly proposed. Variations in the contaminant concentration and use of different contaminants lead to the changes of these parameters measured on-line. In the statistical optical analysis methodology, statistical auto- and cross-characteristics (e.g. auto- and cross-correlation functions, auto- and cross-spectrums, transfer function, coherence function, etc) are used for the analysis of combined object-lubricant images. Both proposed methodologies utilize the comparison of measured parameters and calculated object shape-based and statistical characteristics for fresh and contaminated lubricants. Developed methodologies are verified experimentally showing an ability to distinguish lubricant with 0%, 3%, 7% and 10% water and coolant contamination. This proves the potential applicability of the developed methodologies for on-line measurement, monitoring and control of the engine lubricant condition. © 2012 IOP Publishing Ltd.
Keywords: Automotive engine; Coherence function; Combustion engines; condition; Contaminant concentrations; Cross-correlation function; Distortion effects; Engine condition monitoring; Engine lubricants; Gray scale intensities; Indirect measurements; Measured parameters; Mechanical components; Monitoring and control; Nonuniformity; On-line measurement; Optical analysis; Optical image; Optical medium; Qualitative analysis; Relative intensity; Shape based; Statistical characteristics; Wear particles; Condition monitoring; Contamination; Coolants; Engines; Environmental impact; Geometrical optics; Impurities; Lubricants; Measurements; Mechanical properties; Monitoring; Optical correlation; Optical properties; Periodic structures; Sensors; Statistical methods; Quality control

Involvement of insulin-like growth factor 1 receptor signaling in the amyloid-β peptide oligomers-induced p75 neurotrophin receptor protein expression in mouse hippocampus - Ito, S.; Ménard, M.; Atkinson, T.; Gaudet, C.; Brown, L.; Whitfield, J.; Chakravarthy, B. (Journal of Alzheimer's Disease, 2012)
The p75 neurotrophin receptor (p75NTR) has been thought to play a critical role in amyloid-β peptide (Aβ)-mediated neurodegeneration and Aβ metabolism in Alzheimer's disease (AD) brains. Our previous report showed that membrane-associated p75NTR protein expression was significantly increased in the hippocampi of two different strains of transgenic AD mice and was associated with the age-dependent elevation of Aβ1-42 levels. Here, we provide evidence that the Aβ1-42 oligomers known as ADDLs (Aβ-derived diffusible ligands) induce p75NTR protein expression through insulin-like growth factor 1 receptor (IGF-1R) phosphorylation in SH-SY5Y human neuroblastoma cells. An in vivo microinjection study demonstrated that microinjected ADDLs increased the p75NTR protein expression by 1.4-fold in the ipsilateral hippocampus compared to the contralateral hippocampus. In addition, ADDLs microinjected into mouse hippocampi facilitated IGF-1R phosphorylation within 30 min and the co-administration of picropodophyllin, an IGF-1R kinase inhibitor, blocked ADDLs-induced p75NTR expression. We examined the possible involvement of IGF-1R in the increased p75NTR protein expression in the hippocampi of 6-month-old AβPPswe/PS1dE9 AD model mice that had accumulated significant amounts of Aβ1-42 and showed significantly higher p75NTR expression than age-matched wild-type mice. We found that IGF-1R phosphorylation in these transgenic mice was higher than that in the wild-type mice. These findings indicate that Aβ1-42 oligomers stimulate the p75NTR protein expression in the hippocampus through IGF-1R signaling. Thus, Aβ1-42 oligomers-mediated IGF-1R activation may trigger an increase in p75NTR protein expression in the hippocampus of AD brain during the early stages of disease development. © 2012-IOS Press and the authors. All rights reserved.
Keywords: amyloid beta protein[1-42]; neurotrophin receptor p75; oligomer; somatomedin C receptor; Alzheimer disease; animal experiment; animal model; animal tissue; article; controlled study; disease model; female; hippocampus; human; human cell; in vivo study; male; microinjection; mouse; neuroblastoma cell; nonhuman; priority journal; protein expression; protein phosphorylation; transgenic mouse; wild type; Amyloid beta-Peptides; Animals; Cell Line, Tumor; Female; Gene Expression Regulation; Hippocampus; Humans; Male; Mice; Mice, Inbred C57BL; Mice, Transgenic; Peptide Fragments; Receptor, IGF Type 1; Receptors, Nerve Growth Factor; Signal Transduction

Mesoporous nanostructured Nb-doped titanium dioxide microsphere catalyst supports for PEM fuel cell electrodes - Chevallier, L.; Bauer, A.; Cavaliere, S.; Hui, R.; Rozière, J.; Jones, D.J. (ACS Applied Materials and Interfaces, 2012)
Crystalline microspheres of Nb-doped TiO 2 with a high specific surface area were synthesized using a templating method exploiting ionic interactions between nascent inorganic components and an ionomer template. The microspheres exhibit a porosity gradient, with a meso-macroporous kernel, and a mesoporous shell. The material has been investigated as cathode electrocatalyst support for polymer electrolyte membrane (PEM) fuel cells. A uniform dispersion of Pt particles on the Nb-doped TiO 2 support was obtained using a microwave method, and the electrochemical properties assessed by cyclic voltammetry. Nb-TiO 2 supported Pt demonstrated very high stability, as after 1000 voltammetric cycles, 85% of the electroactive Pt area remained compared to 47% in the case of commercial Pt on carbon. For the oxygen reduction reaction (ORR), which takes place at the cathode, the highest stability was again obtained with the Nb-doped titania-based material even though the mass activity calculated at 0.9 V vs RHE was slightly lower. The microspherical structured and mesoporous Nb-doped TiO 2 is an alternative support to carbon for PEM fuel cells. © 2012 American Chemical Society.
Keywords: Doped titania; Electroactive; Electrocatalyst support; High specific surface area; High stability; Inorganic components; Ionic interaction; Mass activity; Mesoporous; Mesoporous shell; Microwave methods; Nano-structured; Oxygen reduction reaction; PEM fuel cell; Porosity gradients; Pt particle; Supported Pt; Templating method; TiO; Uniform dispersions; Voltammetric cycles; Cathodes; Cyclic voltammetry; Electrocatalysts; Electrolytic reduction; Mesoporous materials; Microspheres; Platinum; Proton exchange membrane fuel cells (PEMFC); Titanium dioxide

Global gene deletion analysis exploring yeast filamentous growth - Ryan, O.; Shapiro, R.S.; Kurat, C.F.; Mayhew, D.; Baryshnikova, A.; Chin, B.; Lin, Z.-Y.; Cox, M.J.; Vizeacoumar, F.; Cheung, D.; Bahr, S.; Tsui, K.; et al. (Science, 2012)
The dimorphic switch from a single-cell budding yeast to a filamentous form enables Saccharomyces cerevisiae to forage for nutrients and the opportunistic pathogen Candida albicans to invade human tissues and evade the immune system. We constructed a genome-wide set of targeted deletion alleles and introduced them into a filamentous S. cerevisiae strain, S1278b. We identified genes involved in morphologically distinct forms of filamentation: haploid invasive growth, biofilm formation, and diploid pseudohyphal growth. Unique genes appear to underlie each program, but we also found core genes with general roles in filamentous growth, including MFG1 (YDL233w), whose product binds two morphogenetic transcription factors, Flo8 and Mss11, and functions as a critical transcriptional regulator of filamentous growth in both S. cerevisiae and C. albicans.
Keywords: green fluorescent protein; transcription factor; transcription factor flo8; transcription factor Mss11; unclassified drug; gene expression; genome; growth; immune system; nutrient cycling; polyploidy; yeast; allele; article; biofilm; Candida albicans; cell structure; fungus growth; gene deletion; gene expression; gene identification; haploidy; nonhuman; phenotype; priority journal; promoter region; protein binding; protein localization; Saccharomyces cerevisiae; signal transduction; transcription regulation; Candida albicans; Saccharomyces cerevisiae; Saccharomycetales

Hexane fraction of American ginseng suppresses colitis and colon cancer - Response - Poudyal, D.; Le, P.M.; Davis, T.; Hofseth, A.B.; Chumanevich, A.; Chumanevich, A.A.; Wargovich, M.J.; Nagarkatti, M.; Nagarkatti, P.S.; Windust, A.; Hofseth, L.J. (Cancer Prevention Research, 2012)
Keywords: ginseng extract; hexane; antiinflammatory activity; colitis; colon cancer; drug carcinogenicity; fractionation; ginseng; LD 50; letter; nonhuman; priority journal

Oocyte development and vitellogenin production in Northwest Atlantic Greenland halibut Reinhardtius hippoglossoides - Rideout, R.M.; Morgan, M.J.; Lambert, Y.; Cohen, A.M.; Banoub, J.H.; Treble, M. (Journal of Northwest Atlantic Fishery Science, 2012)
Histological data presented here supports the notion of an uncommon oocyte development pattern for Greenland halibut, with two simultaneous groups of developing oocytes in the ovary, the larger group developing for the upcoming spawning season and the smaller group developing for next year (i.e. the duration of vitellogenesis is > 1 yr.). We analyzed blood samples collected from wild fish as well as fish that were part of the first documented study of Greenland halibut reproductive development in captivity in order to explore the annual cycle of vitellogenin production for this species. Despite the unusual oocyte development strategy there were no obvious differences in seasonal vitellogenin profiles versus fish with more traditional oocyte development strategies. Blood plasma vitellogenin levels generally peaked prior to or during spawning for those fish that successfully spawned, while patterns were highly variable for fish that did not spawn. Maximum plasma vitellogenin levels observed were 25 mg/ml and within the range of values observed for other fish species. Continued refinements in husbandry and experimental protocols for the study of Greenland halibut in captivity will provide a valuable tool for examining aspects of the species' biology that are difficult to ascertain based on sampling of only wild fish. © Her Magesty the Queen in right of Canada, 2012.
Keywords: captivity; commercial species; developmental stage; fish; reproduction; reproductive behavior; spawning; Atlantic Ocean; Atlantic Ocean (Northwest)

Aspects of in-situ consolidation of thermoplastic laminates manufactured by Automated Tape Placement - Brulotte, X.G.; Hubert, P.; Hojjati, M. (International SAMPE Technical Conference, 2012)
This paper focuses on the manufacturing of thermoplastic composite PEEK parts using Automated Tape Placement (ATP) with in-situ consolidation. The choice of the adequate processing parameters for the in-situ ATP is critical because no additional autoclave step is used to correct any manufacturing imperfections created during layup, or to homogenize the laminate consolidation. The current paper can be considered as a first step towards understanding the deformation behaviour of APC-2/IM7 (Cytec) in-situ ATP tape material subjected to various processing conditions. Compression analyses performed using a Dynamic Mechanical Analyzer (DMA) show that the material can quickly reach a steady state transverse deformation. The deformation behaviour of the pre-impregnated carbon/PEEK tape was investigated using a specially developed compaction apparatus. Processing parameters such as temperature, consolidation forces, and orientation of the deposited tow were independently controlled and the material's steady state deformation was measured by optical microscopy. The processing temperature was found to have negligible impact within the studied range. The consolidation pressure and ply orientation were found to contribute with similar magnitude to the tow deformation.
Keywords: Automated tape placement; Carbon/PEEK; Consolidation pressure; Deformation behaviour; Dynamic mechanical analyzer; In-situ; Manufacturing imperfections; Ply orientation; Processing condition; Processing parameters; Processing temperature; Steady state; Steady state deformation; Thermoplastic composite; Tow deformations; Transverse deformation; Compaction; Deformation; Exhibitions; Laminates; Manufacture; Optical microscopy; In situ processing

Environmental and dwell effects on the damage tolerance properties of ATI 718PLUS® alloy - Kearsey, R. M.; Tsang, J.; Oppenheimer, S.; McDevitt, E. (Superalloys 2012, 2012)
Fatigue crack growth rate (FCGR) and dwell-FCGR tests were conducted at 704C° in a vacuum environment and compared with data obtained under lab air conditions for various microstructural conditions of ATI 718Plus Alloy (718Plus) and Waspaloy. The results indicated that environmental damage has a significant impact on the FCGR characteristics of both alloys, particularly in the near-threshold regime. The dwell fatigue crack propagation behaviour under vacuum conditions displayed identical behaviour irrespective of differences in microstructural features. The observed crack growth rates under vacuum decreased dramatically compared to lab air test results, highlighting the crucial impact of environmental damage on the dwell-fatigue crack propagation resistance of both alloys. The fracture mode for 718Plus was observed to be predominately intergranular in both the FCGR and dwell-FCGR test conditions, with the effect of long-term thermal exposure leading to a larger fraction of transgranular failure. Waspaloy fracture surfaces revealed a predominantly transgranular deformation mode. The fracture surfaces of 718Plus and Waspaloy all exhibited transgranular fracture under vacuum test conditions and were nearly indistinguishable in crack topography. Dynamic embrittlement is believed to be the governing mechanism for intergranular failure of 718Plus leading to grain boundary decohesion. Improvement of dwell-fatigue crack propagation resistance of 718Plus may be strongly related to the coarsening of the γ hardening phase, with potential further improvement via implementation of a bimodal γ heat treatment. EDX analysis showed that the 8 phase just at the crack tip becomes oxidized and may be a contributing factor in the susceptibility of the grain boundaries during the dwell-FCGR tests. The presence of Nb-rich carbides along the dwell-fatigue crack path of 718Plus was also identified. Carbides located behind the crack front were heavily oxidized and those carbides observed just ahead of the crack tip showed no oxidation. It is believed that oxidation of these NbC particles near grain boundaries may be linked to the environmental susceptibility of 718Plus during dwell-fatigue crack propagation. © 2012 The Minerals, Metals, & Materials Society. All rights reserved.
Keywords: Dwell fatigue; Environmental damage; FCGR; Intergranular fracture; Waspaloy; Carbides; Cerium alloys; Crack tips; Cracks; Fatigue crack propagation; Fatigue of materials; Grain boundaries; Microstructural evolution; Oxidation; Stress corrosion cracking; Superalloys; Textures; Vacuum; Fracture

Characterization of 2,3-and 2,6-sialyltransferases from Helicobacter acinonychis - Schur, M.J.; Lameignere, E.; Strynadka, N.C.J.; Wakarchuk, W.W. (Glycobiology, 2012)
Genome sequence data were used to clone and express two sialyltransferase enzymes of the GT-42 family from Helicobacter acinonychis ATCC 51104, a gastric disease isolate from Cheetahs. The deposited genome sequence for these genes contains a large number of tandem repeat sequences in each of them: HAC1267 (RQKELE)15 and HAC1268 (EEKLLEFKNI)13. We obtained two clones with different numbers of repeat sequences for the HAC1267 gene homolog and a single clone for the HAC1268 gene homolog. Both genes could be expressed in Escherichia coli and sialyltransferase activity was measured using synthetic acceptor substrates containing a variety of terminal sugars. Both enzymes were shown to have a preference for N-acetyllactosamine, and they each made a product with a different linkage to the terminal galactose. HAC1267 is a mono-functional 2,3-sialyltransferase, whereas HAC1268 is a mono-functional α2,6- sialyltransferase and is the first member of GT-42 to show α2,6- sialyltransferase activity. © 2012 The Author.
Keywords: alpha 2,3 sialyltransferase; alpha 2,6 sialyltransferase; galactose; sialyltransferase; unclassified drug; aminosugar; bacterial protein; beta D galactoside alpha 2 6 sialyltransferase; beta galactoside alpha 2,3 sialyltransferase; beta-D-galactoside alpha 2-6-sialyltransferase; beta-galactoside alpha-2,3-sialyltransferase; hybrid protein; magnesium; manganese; n acetyllactosamine; N-acetyllactosamine; sialic acid derivative; sialyltransferase; article; bacterial genome; bacterium isolate; cheetah; controlled study; enzyme activation; enzyme analysis; enzyme substrate; Escherichia coli; gene expression; gene sequence; Helicobacter; Helicobacter acinonychis; molecular cloning; nonhuman; nucleotide sequence; priority journal; protein expression; sequence homology; tandem repeat; biosynthesis; chemical structure; chemistry; conformation; enzyme active site; enzyme specificity; enzymology; genetics; glycosylation; pH; structural homology; Escherichia coli; Helicobacter; Helicobacter acinonychis; Amino Sugars; Bacterial Proteins; Carbohydrate Conformation; Catalytic Domain; Cloning, Molecular; Glycosylation; Helicobacter; Hydrogen-Ion Concentration; Magnesium; Manganese; Models, Molecular; Recombinant Fusion Proteins; Sialic Acids; Sialyltransferases; Structural Homology, Protein; Substrate Specificity

Structural characterization and mechanical evaluation of bioactive glass 45S5 foams obtained by a powder technology approach - Aguilar-Reyes, E.A.; León-Patiño, C.A.; Jacinto-Diaz, B.; Lefebvre, L.-P. (Journal of the American Ceramic Society, 2012)
Bioactive glass 45S5 foams were produced using a powder technology process developed by The National Research Council Canada-Industrial Materials Institute. NRC-IMI's proprietary process, combining powder technology and polymer foam technique, allows the production of materials having different structures and properties. It can be used to produce components into various forms, such as fully porous bodies or coatings on solid structures. During foaming, the foaming agent is decomposed and expands the binder-bioactive glass suspension. Then, the binder is burnt out by heating the sample at 500°C and finally the bioactive glass particle network is sintered to consolidate the material. Foams sintered at various temperatures were characterized from a microstructural and mechanical point of view. The foam structure and properties are affected by the sintering temperature when it is varied between 950°C and 1025°C. Foams exhibited open porosity (64%-79%) and pore size (335-530 μm) optimal for bone ingrowth. In all cases, the glass crystallized during sintering and the material was mostly composed of Na6Ca 3Si6O18 and Na2Ca 4(PO4)2SiO4 phases. The mechanical strength increased from 1.7 to 5.5 MPa while the density of the material increased from 0.56 to 0.97 g/cm3. © 2012 The American Ceramic Society.
Keywords: Bone ingrowth; Different structure; Foam structure; Glass particles; Mechanical evaluation; Mechanical points; Micro-structural; National Research Council; Open porosity; Polymer foams; Porous bodies; Powder Technology; Sintering temperatures; Solid structures; Structural characterization; Binders; Bioactive glass; Industrial research; Sintering; Sodium; Strength of materials

ZZ Cyg: fundamental parameters - Nelson, Robert H. (Information Bulletin on Variable Stars, 2012)

Evidence that the bursting component of the X-ray radiation from 3C 111 originates in the PC-scale jet - Bell, M.B.; Comeau, S.P. (Astrophysics and Space Science, 2012)
Evidence is presented indicating that the bursting component of the X-ray radiation detected in the nuclear region of the active radio galaxy 3C 111 comes from the blobs ejected in the pc-scale jet and not from the accretion disc. After each new outburst the radio flux density associated with it increases to a peak in ~1 year and then subsides over a period of 1-2 years with the flux falling off exponentially as the blob moves outward and dissipates. Similar peaks (bursts) are seen in the X-ray light curve and a cross-correlation between the two shows a very high correlation with the X-ray peaks leading the radio peaks by ~100 days. A second cross-correlation, this time between the radio event start times and the X-ray light curve, also shows a significant correlation. When this is taken together with the long (~1 yr) delay between the start of each ejection event and its associated X-ray peak it indicates that this bursting component of the X-ray flux must be associated with the ejected blobs in the pc-scale jet and not with the accretion disc. Because X-ray telescopes do not have the resolution required to resolve the accretion disc area from the pc-scale jet, this paper is the first to present observational evidence that can pinpoint the point of origin of at least those long-timescale X-ray bursts with durations of 1-3 yrs. © 2011 Springer Science+Business Media B.V.

Metal frame reinforced ceramic matrix composite for high temperature applications - Kibsey, M.; Mohammadi, T.; Huang, X.; Kearsey, R. (Proceedings of the ASME Turbo Expo, 2012)
The design, fabrication and preliminary assessment of novel metal reinforced ceramic matrix composite (CMC) materials are reported in this study. The design is based on the assumption that the metallic reinforcing structure can increase the work of fracture through the action of wire pullout, crack deflection and plastic deformation. In particular, the current CMC is composed of a molybdenum wire structure within a 7.5 wt% yttria-stabilized zirconia (7YSZ) ceramic matrix (Mo/YSZ). A unique jig is designed to assist the fabrication of the Mo mesh. Subsequently a NiCrAlY bond coat and finally a 7YSZ matrix are applied to the Mo mesh structure using a plasma spray technique. The as-fabricated and heat treated Mo/YSZ are subjected to impact and 3-point bend tests. The impact testing results show that heat treatment after spraying increases the impact energy possibly due to the improved bonding between Mo, NiCrAlY and 7YSZ. During 3-point bend testing, the incorporation of Mo mesh in 7YSZ increases the load at yield point, the peak load and the displacement to failure. After isothermal and cyclic oxidation tests at 1050°C for 330 hours, the Mo/YSZ CMC is examined under optical and scanning electron microscopes (SEM). The results show that the NiCrAlY bond coat delaminates from the Mo wire and also forms radial cracks during the spraying process. It is for this reason that the Mo wire suffers from rapid oxidization during isothermal and cyclic oxidation tests, causing separation of the reinforcement from the 7YSZ matrix. Future improvement to the current process will be to select and deposit a more effective oxidation resistant coating on the Mo wire in order to allow the metal frame-reinforced CMC concept to achieve the desired chemical and mechanical properties at high temperatures. Copyright © 2012 by ASME.
Keywords: Cyclic oxidation tests; Future improvements; Mechanical properties at high temperatures; NiCrAlY bond coats; Oxidation resistant coating; Plasma spray techniques; Preliminary assessment; The scanning electron microscopes (SEM); Ceramic matrix composites; Chemical bonds; Cracks; Exhibitions; Fabrication; Fracture; Gas turbines; High temperature applications; Impact testing; Isotherms; Jigs; Load testing; Mechanical properties; Molybdenum; Plasma spraying; Reinforcement; Scanning electron microscopy; Yttria stabilized zirconia; Zirconia; Wire

Characterization of the PEM fuel cell catalyst layer microstructure by nonlinear least-squares parameter estimation - Dobson, P.; Lei, C.; Navessin, T.; Secanell, M. (Journal of the Electrochemical Society, 2012)
Models of polymer electrolyte membrane fuel cells (PEMFC) have become increasingly complex, using many parameters to define the behavior of species and the performance of the cell. A framework is presented here to couple an agglomerate electrode based, multi-dimensional, multi-physics mathematical model of membrane electrode assembly (MEA) model with an optimization-based nonlinear least-squares parameter estimation algorithm. The framework is used to estimate the micro-structural parameters of the catalyst layer such as agglomerate size. The results show that a set of data over a range of operating conditions can be accurately described by using a unique set of structural parameters that match experimental visualization of the catalyst layer. Extension of this methodology can be used to systematically estimate any model parameters in order to reduce uncertainty in model predictions. © 2012 The Electrochemical Society.
Keywords: Agglomerate sizes; Catalyst layers; Experimental visualization; Membrane electrode assemblies; Microstructural parameters; Model parameters; Model prediction; Multi-physics; Nonlinear least squares; Operating condition; Parameter estimation algorithm; PEM fuel cell; Structural parameter; Catalysts; Mathematical models; Parameter estimation; Uncertainty analysis; Proton exchange membrane fuel cells (PEMFC)

Linear friction welding of a forged near-α titanium alloy - Dalgaard, E.; Wanjara, P.; Gholipour, J.; Jonas, J.J. (Materials Science Forum, 2012)
IMI834 (Ti-5.8Al-4Sn-3.5Zr-0.7Nb-0.5Mo-0.35Si) is a high-tech near-α titanium alloy with improved creep resistance and mechanical property retention at temperatures up to 600°C [1]. It is used in the aerospace industry for compressor disks and blades due to its excellent balance between creep resistance and fatigue strength [2]. The linear friction welding (LFW) behaviour of IMI834 displaying an initial bimodal α+β microstructure was investigated using varying axial pressures during welding. Electron backscatter diffraction (EBSD) was used to characterize the texture and phase fraction of the welded IMI834 samples in the weld zone (WZ) and thermomechanically affected zones (TMAZ) in relation to the base material. Based on microhardness evaluation of the weldments, the WZ was determined to be slightly harder than the base material. © 2012 Trans Tech Publications, Switzerland.
Keywords: Aerospace; Axial pressures; Base material; Compressor disks; Electron back scatter diffraction; Fatigue strength; IMI834; Linear friction welding; Phase fractions; Thermomechanically affected zones; Weld zone; Weldments; Aerospace industry; Friction welding; Textures; Tin; Titanium alloys; Welding; Zirconium; Alloys; Cerium alloys; Creep; Creep resistance; Friction; Molybdenum; Niobium; Titanium; Tribology; Creep resistance; Titanium alloys

Partial oligomerization of pyolysin induced by a disulfide-tethered mutant - Pokrajac, L.; Baik, C.; Harris, J.R.; Sarraf, N.S.; Palmer, M. (Biochemistry and Cell Biology, 2012)
The bacterial toxin pyolysin (PLO) belongs to the family of cholesterol-dependent cytolysins (CDCs), which form large, ring-shaped oligomeric pores in cholesterol-containing membranes. Monomeric CDC molecules have a structure of four domains, with domains 2 and 3 packed against each other. After binding to target membranes containing cholesterol, toxin monomers oligomerize into pre-pore complexes. Trans-membrane pores form when the pre-pores insert into the lipid bilayer. Membrane insertion requires each subunit in the pre-pore to undergo a significant change in conformation, including the separation of domains 2 and 3. We here characterize a pyolysin mutant with an engineered disulfide bond between domains 2 and 3. The disulfide-tethered mutant binds to membranes but does not form oligomers. When mixed with wild type PLO, the two proteins form hybrid oligomers, which are reduced in size and arc-shaped rather than ring-shaped. With equimolar mixtures or the disulfide mutant in slight excess, the hybrid oligomers retain pore-forming activity, while a larger excess of the mutant suppresses pore formation. These results support a "partially cooperative" mode of protein activity, in which a limited number of functional subunits within an oligomer have to cooperate to initiate membrane insertion and pore formation. © 2012 Published by NRC Research Press.
Keywords: Bacterial toxin; Cholesterol-dependent cytolysins; Disulfide bonds; Equimolar mixtures; Hybrid oligomers; Membrane insertion; Pore formation; Protein activity; Pyolysin; Trans-membrane pores; Wild types; Cholesterol; Covalent bonds; Lipid bilayers; Membranes; Oligomerization; Pore size; Proteins; Sulfur compounds; Oligomers; bacterial toxin; disulfide; pyolysin; unclassified drug; Arcanobacterium pyogenes; article; bacterial mutation; bacterium mutant; channel gating; complex formation; controlled study; Escherichia coli; gene insertion; hemolysis; oligomerization; Bacterial Proteins; Bacterial Toxins; Binding Sites; Cell Membrane; Cytotoxins; Disulfides; Hemolysin Proteins; Mutation; Polymerization; Protein Conformation; Protein Subunits; Bacteria (microorganisms)

Probabilistic models for focused web crawling - Liu, H.; Milios, E. (Computational Intelligence, 2012)
A focused crawler is an efficient tool used to traverse the Web to gather documents on a specific topic. It can be used to build domain-specific Web search portals and online personalized search tools. Focused crawlers can only use information obtained from previously crawled pages to estimate the relevance of a newly seen URL. Therefore, good performance depends on powerful modeling of context as well as the quality of the current observations. To address this challenge, we propose capturing sequential patterns along paths leading to targets based on probabilistic models. We model the process of crawling by a walk along an underlying chain of hidden states, defined by hop distance from target pages, from which the actual topics of the documents are observed. When a new document is seen, prediction amounts to estimating the distance of this document from a target. Within this framework, we propose two probabilistic models for focused crawling, Maximum Entropy Markov Model (MEMM) and Linear-chain Conditional Random Field (CRF). With MEMM, we exploit multiple overlapping features, such as anchor text, to represent useful context and form a chain of local classifier models. With CRF, a form of undirected graphical models, we focus on obtaining global optimal solutions along the sequences by taking advantage not only of text content, but also of linkage relations. We conclude with an experimental validation and comparison with focused crawling based on Best-First Search (BFS), Hidden Markov Model (HMM), and Context-graph Search (CGS). © 2012 Wiley Periodicals, Inc.
Keywords: Best first search; Conditional random field; Domain specific; Experimental validations; Focused crawler; Focused crawling; Focused web crawling; Global optimal solutions; GraphicaL model; Hidden state; Hop distance; Link analysis; Local classifier; Maximum entropy Markov model; Overlapping features; Personalized search; Probabilistic models; Sequential patterns; Text content; Topical crawlers; Web Mining; Web searches; Hidden Markov models; Learning systems; Websites; Learning algorithms

A search for ob associations near southern long-period cepheids. V. AQ puppis and V620 puppis - Turner, D.G.; Van Den Bergh, S.; Younger, P.F.; Majaess, D.J.; Pedreros, M.H.; Berdnikov, L.N. (Astronomical Journal, 2012)
A photometric UBV survey is presented for 610 stars in a region surrounding the Cepheid AQ Puppis and centered southwest of the variable, based upon photoelectric measures for 14 stars and calibrated iris photometry of photographic plates of the field for 596 stars. An analysis of reddening and distance for program stars indicates that the major dust complex in this direction is ∼1.8 kpc distant, producing differential extinction described by a ratio of total-to-selective extinction of R = A V /E B-V = 3.10 ± 0.20. Zero-age main-sequence fitting for the main group of B-type stars along the line of sight yields a distance of 3.21 ± 0.19 kpc (V 0 - M V = 12.53 ± 0.13 s.e.). The 2997 Cepheid AQ Pup, of field reddening E B-V = 0.47 ± 0.07 (E B-V (B0) = 0.51 ± 0.07), appears to be associated with B-type stars lying within 5′ of it as well as with a sparse group of stars, designated Turner 14, centered south of it at J2000.0 = 07:58:37, -29:25:00, with a mean reddening of E B-V = 0.81 ± 0.01. AQ Pup has an inferred luminosity as a cluster member of 〈M V 〉 = -5.40 ± 0.25 and an evolutionary age of 3 × 10 7 yr. Its observed rate of period increase of +300.1 ± 1.2 s yr -1 is an order of magnitude larger than what is observed for Cepheids of comparable period in the third crossing of the instability strip, and may be indicative of a high rate of mass loss or a putative fifth crossing. Another sparse cluster, designated Turner 13, surrounds the newly recognized 259 Cepheid V620 Pup, of space reddening E B-V = 0.64 ± 0.02 (E B-V (B0) = 0.68 ± 0.02), distance 2.88 ± 0.11 kpc (V 0-M V = 12.30 ± 0.08 s.e.), evolutionary age 10 8 yr, and an inferred luminosity as a likely cluster member of 〈M V 〉 = -2.74 ± 0.11. V620 Pup is tentatively identified as a first crosser, pending additional observations. © 2012. The American Astronomical Society. All rights reserved.

Electronic properties of Si(111)-7×7 and related reconstructions: Density functional theory calculations - Smeu, M.; Guo, H.; Ji, W.; Wolkow, R.A. (Physical Review B - Condensed Matter and Materials Physics, 2012)
The 7×7 reconstruction of Si(111) has the interesting property of being metallic despite bulk Si being a semiconductor. This surface has a complex reconstruction that takes on a dimer-adatom stacking fault (DAS) structure composed of adatoms, rest atoms, and several other key features. It is believed that the dangling bonds of the adatoms play a crucial role in the high conductivity and that this is predominantly a surface-state band effect. To elucidate the details of this mechanism, we investigate a set of related Si(111) reconstructions of increasing complexity in order to resolve the effect of the different DAS features on the electronic and transport properties of the Si(111)-7×7 surface. Density functional theory calculations are carried out on the √3×√3-R30 -, 2×2, 5×5, and 7×7 reconstructions of Si(111). Since these surfaces are modeled as two-dimensional slabs, a careful investigation is carried out to determine the slab thickness needed to capture the structural and electronic properties of these systems. The densities of states (DOSs) projected on different atoms in these surfaces are then compared, revealing that the √3×√3, 5×5, and 7×7 surfaces are metallic, while the 2×2 surface is semiconducting. Finally, the DOSs for Si(111)-7×7 are related to scanning tunneling microscope data to offer an explanation for different adatom prominence trends depending on Si sample doping. © 2012 American Physical Society.

Multiband sensor using thick holographic gratings for sulfur detection by laser-induced breakdown spectroscopy - Gagnon, D.; Lessard, S.; Verhaegen, M.; Mutchmore, P.; Bouchard, P.; Doucet, F.R.; Sabsabi, M. (Applied Optics, 2012)
Detection of sulfur by optical emission spectroscopy generally presents some difficulties because the strongest lines are in the vacuum UV below 185 nm and therefore are readily absorbed by oxygen molecules in air. A novel concept for a low-cost and efficient system to detect sulfur using near-IR bands by laser-induced breakdown spectroscopy is here proposed. This concept is based on customized thick holographic gratings as spectral filtering elements. The signal integration and the temporal synchronization are performed using built-in custom electronics that amplify and integrate or trigger photodiode output signals. In this work, we use the near-IR lines at 921.287 nm and a background reference at 900 nm. Preliminary results show a limit of detection comparable to that of a conventional high-end system. © 2012 Optical Society of America.
Keywords: Efficient systems; High-end systems; Limit of detection; Multi-band sensors; Near-IR; Novel concept; Output signal; Oxygen molecule; Signal integration; Spectral filtering; Sulfur detection; Temporal synchronization; Vacuum UV; Atomic emission spectroscopy; Holographic gratings; Sulfur; Signal detection

Synthetic archaeosome vaccines containing triglycosylarchaeols can provide additive and long-lasting immune responses that are enhanced by archaetidylserine - Sprott, G.D.; Yeung, A.; Dicaire, C.J.; Yu, S.H.; Whitfield, D.M. (Archaea, 2012)
The relation between archaeal lipid structures and their activity as adjuvants may be defined and explored by synthesizing novel head groups covalently linked to archaeol (2,3-diphytanyl-sn-glycerol). Saturated archaeol, that is suitably stable as a precursor for chemical synthesis, was obtained in high yield from Halobacterium salinarum. Archaeosomes consisting of the various combinations of synthesized lipids, with antigen entrapped, were used to immunize mice and subsequently determine CD8+ and CD4+-T cell immune responses. Addition of 45 mol of the glycolipids gentiotriosylarchaeol, mannotriosylarchaeol or maltotriosylarchaeol to an archaetidylglycerophosphate-O-methyl archaeosome, significantly enhanced the CD8+ T cell response to antigen, but diminished the antibody titres in peripheral blood. Archaeosomes consisting of all three triglycosyl archaeols combined with archaetidylglycerophosphate-O-methyl (15/15/15/55 mol) resulted in approximately additive CD8+ T cell responses and also an antibody response not significantly different from the archaetidylglycerophosphate-O- methyl alone. Synthetic archaetidylserine played a role to further enhance the CD8+ T cell response where the optimum content was 2030 mol. Vaccines giving best protection against solid tumor growth corresponded to the archaeosome adjuvant composition that gave highest immune activity in immunized mice. © 2012 G. Dennis Sprott et al.
Keywords: Archaea; Halobacterium salinarum; Mus; antibody; archaeol lipid; cancer vaccine; glycerol ether; glycolipid; immunological adjuvant; tumor antigen; animal; article; blood; C57BL mouse; CD4+ T lymphocyte; CD8+ T lymphocyte; chemistry; Halobacterium salinarum; immunology; isolation and purification; mouse; neoplasm; pathology; Adjuvants, Immunologic; Animals; Antibodies; Antigens, Neoplasm; Cancer Vaccines; CD4-Positive T-Lymphocytes; CD8-Positive T-Lymphocytes; Glyceryl Ethers; Glycolipids; Halobacterium salinarum; Mice; Mice, Inbred C57BL; Neoplasms

Effect of single-walled carbon nanotubes on processing and property enhancement of epoxy adhesives and laminates - Ashrafi, B.; Johnston, A.; Jakubinek, M.B.; Martinez-Rubi, Y.; Simard, B.; Hubert, P. (International SAMPE Technical Conference, 2012)
In this work, the effects of single walled carbon nanotubes (SWCNTs) on mechanical and electrical properties of two epoxy resins (a high temperature aerospace-grade epoxy and an aerospace-grade adhesive) were evaluated. The performance of these two SWCNT-modified epoxy resins was also studied in their end-use applications, as a matrix for a glass fiber laminate composites and as an adhesive for aluminum-to-aluminum bonding, respectively. The results suggest that the mechanical and electrical property improvements observed in bulk resin due the addition of SWCNTs do not necessarily translate into comparable property enhancements in laminates and joints. It was found that the electrical property improvements of nano-modified laminates exceeded those of bulk SWCNT-modified epoxy. The translation of mechanical properties from bulk resin to the structural level, on the other hand, was found to be less successful. The results are discussed in terms of challenges associated with processing and resin-fiber interaction.
Keywords: End-uses; Epoxy adhesives; High temperature; Laminate composites; Mechanical and electrical properties; Property improvement; Aluminum; Electric properties; Exhibitions; Glass fibers; Laminated composites; Mechanical properties; Resins; Single-walled carbon nanotubes (SWCN); Epoxy resins

Structure and stability of an amorphous water-methane mixture produced by cold compression of methane hydrate - Tulk, C.A.; Klug, D.D.; Molaison, J.J.; Dos Santos, A.M.; Pradhan, N. (Physical Review B - Condensed Matter and Materials Physics, 2012)
In a process similar to the formation of high-density amorphous ice, amorphous methane hydrate was formed by the pressure-induced collapse of crystalline methane clathrate at 32 kbar and 100 K. This produced a regular array of methane embedded within cavities in an amorphous water network. In situ annealing results in further densification into a more disordered and higher density amorphous state before crystallization into ice VIII and hexagonal clathrate. Whereas the very high-density amorphous form of pure water undergoes a glass transition near 130 K at low pressure and crystallizes over a broad pressure range at ∼160 K, the amorphous network of the water-methane binary system exhibits a region of metastability that persists up to 220 K between 15 and 40kbar. It appears that in this system the connectivity of the water network exhibits sufficiently low mobility so as to inhibit the diffusion and phase separation of the constituents until 220 K, where the high-pressure ice VIII crystallization can occur. The structure of the amorphous form is studied by neutron diffraction and the hydration of methane in this disordered water network is more closely related to the small clathrate cage than the large. ©2012 American Physical Society.

Robot task planning and trajectory learning for flexible automation - Mantegh, I. (Proceedings of the ASME Design Engineering Technical Conference, 2012)
A task planning method is presented to model and reproduce robot trajectories based on those captured from human demonstrations. In the framework of the Programming by Demonstration (PbD) approach, task planning algorithm is developed to determine the general type of trajectory pattern, its parameters, and its kinematic profile. The pattern is described independently of the shape of the surface on which it is demonstrated. Key pattern points are identified based on changes in direction and velocity, and are then reduced based on their proximity. The results of the analysis are provided are used inside a task planning algorithm, to produce robot trajectories based on the workpiece geometries. The trajectory is output in the form of robot native language code so that it can be readily downloaded on the robot. © 2012 by ASME.
Keywords: Flexible automation; Human demonstrations; Key Patterns; Native language; Programming by demonstration; Robot trajectory; Task planning; Trajectory pattern; Algorithms; Design; Robots; Trajectories; Robot programming