1,106 research outputs found

    Streaking images that appear only in the plane of diffraction in undoped GaAs single crystals: Diffraction imaging (topography) by monochromatic synchrotron radiation

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    Streaking images restricted to the direction of the diffraction (scattering) vector have been observed on transmission through undoped GaAs. These disruption images (caused by the reduction of diffraction in the direction of observation) appear both in the forward and in Bragg diffracted directions in monochromatic synchrontron radiation diffraction imaging. This previously unobserved phenomenon can be explained in terms of planar defects (interfaces) or platelets which affects the absorption coefficient in anomalous transmission. Such regions of the crystal look perfect despite the presence of imperfections when the scattering vector is not perpendicular to the normal of the platelets. The observed crystallographic orientation of these interfaces strongly indicates that they are antiphase boundaries

    Probability state modeling of memory CD8+ T-cell differentiation

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    AbstractFlow cytometric analysis enables the simultaneous single-cell interrogation of multiple biomarkers for phenotypic and functional identification of heterogeneous populations. Analysis of polychromatic data has become increasingly complex with more measured parameters. Furthermore, manual gating of multiple populations using standard analysis techniques can lead to errors in data interpretation and difficulties in the standardization of analyses. To characterize high-dimensional cytometric data, we demonstrate the use of probability state modeling (PSM) to visualize the differentiation of effector/memory CD8+ T cells. With this model, four major CD8+ T-cell subsets can be easily identified using the combination of three markers, CD45RA, CCR7 (CD197), and CD28, with the selection markers CD3, CD4, CD8, and side scatter (SSC). PSM enables the translation of complex multicolor flow cytometric data to pathway-specific cell subtypes, the capability of developing averaged models of healthy donor populations, and the analysis of phenotypic heterogeneity. In this report, we also illustrate the heterogeneity in memory T-cell subpopulations as branched differentiation markers that include CD127, CD62L, CD27, and CD57

    Проблеми та можливості споживання енергії в Україні

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    Проаналізовано споживання енергії в різних секторах економіки й подано модель визначення потенціалу зниження споживання енергії в Україні. Ключові слова: енергоефективність, енергозбереження, енергоємність, енергоспоживання, потенціал зменшення споживання енергії.Проанализированы потребления энергии в различных секторах экономики и представлена модель определения потенциала снижения потребления энергии в Украине. Ключевые слова: энергоэффективность, энергосбережение, энергоемкость, энергопотребление, потенциал уменьшения потребления энергии.The paper analyses energy consumption in different economic sectors and presents the model of determining the potential of reducing energy consumption in Ukraine. Keywords: energy efficiency, energy saving, energy intensity, energy waste, energy consumption, potential of reducing energy consumption

    A Property Law Reader: Cases, Questions and Commentary, 4th Edition, Preface and Table of Contents

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    Property law — that body of rules which describes and defines relationships between people with respect to things — involves many choices. The choices include determining when it is appropriate and desirable to label something as property or, more accurately, as subject to a relationship between people based in the rules of property law. The choices involve asking questions, including why it is that we create relationships based in property and who should benefit from them. The rules of property law are notoriously difficult and complex, and they frequently appear disjointed and unconnected, but they are not arbitrary. They are based on choices, sometimes made explicitly, other times implicitly, about what is important. One of our principal goals in this collection of property law materials is to emphasize that the making of choices is a necessary, although commonly under-acknowledged, element in creating a regime of property law. We have made a choice to highlight what Margaret Davies has described as ‘‘asking the why question”. This involves using materials that prompt not only an investigation of the rules of property law but also the justifications for those rules. Another choice we have made in compiling this material is to highlight the disparate sources of property law. Excerpts from the decisions of common law courts dominate the page count, and learning to derive the principles and the rules from these decisions is a core element in a common law legal education, but there is much else besides. We have chosen to emphasize Indigenous legal traditions as one of the sources of Canadian property law alongside the civil law tradition in Quebec and the common law tradition (including principles of equity) in the rest of the country. This presents challenges, not the least because the concept or category of property, as it has developed in western legal traditions, sits uneasily with many Indigenous legal traditions. But it is also a useful reminder that the rules governing human relationships with respect to things are not only jurisdictionally, but also culturally and historically specific. The law of property is also to be found in a great diversity of legislative instruments, ranging from city by-laws, through provincial and federal statutes and regulations, to international agreements. These sources are scattered throughout the volume, but using them presents other challenges. Within the Canadian federation, property is primarily a matter of provincial jurisdiction, and the diversity of property regimes among the provinces limits our capacity to delve into the particular statutory framework of any one jurisdiction when producing a set of materials that is relevant across Canadian common law jurisdictions. As a result, we include examples from different jurisdictions and leave it to course instructors to add as much or as little of what is particular to their jurisdictions as they think desirable

    Standard-Level Herbivory in an Old-Growth Conifer Forest Canopy

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    Herbivory is an important ecological process in forest canopies but is difficult to measure, especially for whole stands. We used the Wind River Canopy Crane in Washington State to access 101 randomly-located sample points throughout the forest canopy. This provided a relatively quick and convenient way to estimate herbivory for a whole stand. The overall level of herbivory was estimated at 1.6% of leaf area. The distribution was strongly skewed to the lower canopy where broad-leafed species experienced higher levels of herbivory. Herbivory averaged 0.3% in conifers and 13.5% in broad-leafed species. Fully half of the sample points had no detectable herbivory. Herbivory in this old-growth conifer forest is among the lowest levels published for forests around the globe and may reflect the general levels of herbivory in temperate coniferous forests during nonoutbreak conditions. Our whole-stand estimate is the first attempt at measuring herbivory for an entire forest stand in the Pacific Northwest

    Gene regulatory networks in lactation: identification of global principles using bioinformatics

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    <p>Abstract</p> <p>Background</p> <p>The molecular events underlying mammary development during pregnancy, lactation, and involution are incompletely understood.</p> <p>Results</p> <p>Mammary gland microarray data, cellular localization data, protein-protein interactions, and literature-mined genes were integrated and analyzed using statistics, principal component analysis, gene ontology analysis, pathway analysis, and network analysis to identify global biological principles that govern molecular events during pregnancy, lactation, and involution.</p> <p>Conclusion</p> <p>Several key principles were derived: (1) nearly a third of the transcriptome fluctuates to build, run, and disassemble the lactation apparatus; (2) genes encoding the secretory machinery are transcribed prior to lactation; (3) the diversity of the endogenous portion of the milk proteome is derived from fewer than 100 transcripts; (4) while some genes are differentially transcribed near the onset of lactation, the lactation switch is primarily post-transcriptionally mediated; (5) the secretion of materials during lactation occurs not by up-regulation of novel genomic functions, but by widespread transcriptional suppression of functions such as protein degradation and cell-environment communication; (6) the involution switch is primarily transcriptionally mediated; and (7) during early involution, the transcriptional state is partially reverted to the pre-lactation state. A new hypothesis for secretory diminution is suggested – milk production gradually declines because the secretory machinery is not transcriptionally replenished. A comprehensive network of protein interactions during lactation is assembled and new regulatory gene targets are identified. Less than one fifth of the transcriptionally regulated nodes in this lactation network have been previously explored in the context of lactation. Implications for future research in mammary and cancer biology are discussed.</p

    Using Space Weather Variability in Evaluating the Environment Design Specifications for NASA'S Constellation Program

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    Spectral models of solar particle events and trapped radiation belts are necessary for the design requirements of total ionizing radiation dose, single event effects, and spacecraft charging. Space radiation and plasma environment specifications for hardware design are necessarily conservative to assure system robustness for a wide range of space environments

    Using Space Weather Variability in Evaluating the Radiation Environment Design Specifications for NASA's Constellation Program

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    NASA's Constellation program, initiated to fulfill the Vision for Space Exploration, will create a new generation of vehicles for servicing low Earth orbit, the Moon, and beyond. Space radiation specifications for space system hardware are necessarily conservative to assure system robustness for a wide range of space environments. Spectral models of solar particle events and trapped radiation belt environments are used to develop the design requirements for estimating total ionizing radiation dose, displacement damage, and single event effects for Constellation hardware. We first describe the rationale using the spectra chosen to establish the total dose and single event design environmental specifications for Constellation systems. We then compare variability of the space environment to the spectral design models to evaluate their applicability as conservative design environments and potential vulnerabilities to extreme space weather event

    Overview of NASA Glenn Seal Project

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    NASA Glenn is currently performing seal research supporting both advanced turbine engine development and advanced space vehicle/propulsion system development. Studies have shown that decreasing parasitic leakage through applying advanced seals will increase turbine engine performance and decrease operating costs. Studies have also shown that higher temperature, long life seals are critical in meeting next generation space vehicle and propulsion system goals in the areas of performance, reusability, safety, and cost. NASA Glenn is developing seal technology and providing technical consultation for the Agency s key aero- and space technology development programs

    A Comparison of the Chemical Evolutionary Histories of the Galactic Thin Disk and Thick Disk Stellar Populations

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    We have studied 23 long-lived G dwarfs that belong to the thin disk and thick disk stellar populations. Abundances have been derived for 24 elements: O, Na, Mg, Al, Si, Ca, Ti, Sc, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Sr, Y, Zr, Ba, La, Ce, Nd, and Eu. We find that the behavior of [alpha/Fe] and [Eu/Fe] vs. [Fe/H] are quite different for the two populations. As has long been known, the thin disk O, Mg, Si, Ca, and Ti ratios are enhanced relative to iron at the lowest metallicities, and decline toward solar values as [Fe/H] rises above -1.0. For the thick disk, the decline in [alpha/Fe] and [Eu/Fe] does not begin at [Fe/H] = -1.0, but at -0.4. Other elements share this behavior, including Sc, Co, and Zn, suggesting that at least in the chemical enrichment history of the thick disk, these elements were manufactured in similar-mass stars. Combining our results for the oldest and longest-lived stars with prior work, we find clear signs for an independent origin for the Galactic thick disk. (Abridged)Comment: 48 pages and 20 figures, accepted for publication in the Astronomical Journa
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