3,266 research outputs found

    An iterative method for reference pattern selection in high-resolution electron backscatter diffraction (HR-EBSD)

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    For high (angular) resolution electron backscatter diffraction (HR-EBSD), the selection of a reference diffraction pattern (EBSP0) significantly affects the precision of the calculated strain and rotation maps. This effect was demonstrated in plastically deformed body-centred cubic and face-centred cubic ductile metals (ferrite and austenite grains in duplex stainless steel) and brittle single-crystal silicon, which showed that the effect is not only limited to measurement magnitude but also spatial distribution. An empirical relationship was then identified between the cross-correlation parameter and angular error, which was used in an iterative algorithm to identify the optimal reference pattern that maximises the precision of HR-EBSD

    Light trapping in ultrathin plasmonic solar cells

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    We report on the design, fabrication, and measurement of ultrathin film a-Si:H solar cells with nanostructured plasmonic back contacts, which demonstrate enhanced short circuit current densities compared to cells having flat or randomly textured back contacts. The primary photocurrent enhancement occurs in the spectral range from 550 nm to 800 nm. We use angle-resolved photocurrent spectroscopy to confirm that the enhanced absorption is due to coupling to guided modes supported by the cell. Full-field electromagnetic simulation of the absorption in the active a-Si:H layer agrees well with the experimental results. Furthermore, the nanopatterns were fabricated via an inexpensive, scalable, and precise nanopatterning method. These results should guide design of optimized, non-random nanostructured back reflectors for thin film solar cells

    Flexible structure control laboratory development and technology demonstration

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    An experimental structure is described which was constructed to demonstrate and validate recent emerging technologies in the active control and identification of large flexible space structures. The configuration consists of a large, 20 foot diameter antenna-like flexible structure in the horizontal plane with a gimballed central hub, a flexible feed-boom assembly hanging from the hub, and 12 flexible ribs radiating outward. Fourteen electrodynamic force actuators mounted to the hub and to the individual ribs provide the means to excite the structure and exert control forces. Thirty permanently mounted sensors, including optical encoders and analog induction devices provide measurements of structural response at widely distributed points. An experimental remote optical sensor provides sixteen additional sensing channels. A computer samples the sensors, computes the control updates and sends commands to the actuators in real time, while simultaneously displaying selected outputs on a graphics terminal and saving them in memory. Several control experiments were conducted thus far and are documented. These include implementation of distributed parameter system control, model reference adaptive control, and static shape control. These experiments have demonstrated the successful implementation of state-of-the-art control approaches using actual hardware

    Nurses\u27 Alumnae Association Bulletin - Volume 2 Number 3

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    The Jefferson Nurse Letter from the President Delegates to Biennial Convention Attention Blood Transfusion - Plasma Unit Life in the Army Nurse Corps Secretary\u27s Report Elected to New Office 1892-1942 Progress or Alumnae Association 1892-1942 Report of the School of Nursing Staff News Please Change My Address Air Cooled Red Cross Report Fingerprinting Graduates in the U.S. Army and Navy Degrees Received Promotions Jubilee Report Engagements Marriages Births New Positions - 1941-1942 New Positions on the Nursing Staff of the Hospita

    Crankcase sampling of PM from a fired and motored compression ignition engine

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    Crankcase emissions are a complex mixture of combustion products and aerosol generated from lubrication oil. The crankcase emissions contribute substantially to the total particulate matter (PM) emitted from an engine. Environment legislation demands that either the combustion and crankcase emissions are combined to give a total measurement, or the crankcase gases are re-circulated back into the engine. There is a lack of understanding regarding the physical processes that generate crankcase aerosols, with a paucity of information on the size/mass concentrations of particles present in the crankcase. In this study the particulate matter crankcase emissions were measured from a fired and motored 4 cylinder compression ignition engine at a range of speeds and crankcase locations. A sequence of sampling equipment was used to characterise the emissions in the size range 5 nm - 19 Ī¼m; Cambustion DMS500 fast particulate spectrometer, TSI Scanning Mobility Particle Sizer (SMPS), TSIā„¢ Condensation Particle Counter (CPC) and, TSIā„¢ Aerodynamic Particle Sizer (APS). The combination of the two test engines and range of sampling equipment provided new information on the generation and behavior of aerodynamic particulate matter within an engine crankcase. Data is presented for the effect of controlled parameter changes on number distributions over the measured particle size range. A complex lognormal bimodal size distribution of sub micron accumulation mode particles was present in the crankcase of both engines at a low idle speed of 900rpm. At 1400rpm this complex distribution was not present. Increasing the engine load, on the fired engine, initially reduced the particle number concentration with a final significant increase in particle number concentration at 75% load. At 900 rpm 50% load there was a single strong peak at 32nm in the rocker cover however sampling from the push rod gallery and sump showed a strongly bimodal distribution with peaks at 32nm and 133nm. All other sampling data, from the fired engine, was consistent at each sampling location. The SMPS results, 15-665nm, on the motored engine showed location dependency, with the highest number concentration of particles present in the push rod gallery

    Assignment of the Human and Mouse Prion Protein Genes to Homologous Chromosomes

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    Purified preparations of scrapie prions contain one major macromolecule, designated prion protein (PrP). Genes encoding PrP are found in normal animals and humans but not within the infectious particles. The PrP gene was assigned to human chromosome 20 and the corresponding mouse chromosome 2 using somatic cell hybrids. In situ hybridization studies mapped the human PrP gene to band 20p12ā†’pter. Our results should lead to studies of genetic loci syntenic with the PrP gene, which may play a role in the pathogenesis of prion diseases or other degenerative neurologic disorders

    Gene expression changes in diapause or quiescent potato cyst nematode, Globodera pallida, eggs after hydration or exposure to tomato root diffusate

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    The authors thank the Education Spanish Ministry for the grant provided for the first author under the "Ayudas para la movilidad postdoctoral en centros extranjeros'' scheme. The James Hutton Institute receives funding from the Scottish Government.Plant-parasitic nematodes (PPN) need to be adapted to survive in the absence of a suitable host or in hostile environmental conditions. Various forms of developmental arrest including hatching inhibition and dauer stages are used by PPN in order to survive these conditions and spread to other areas. Potato cyst nematodes (PCN) (Globodera pallida and G. rostochiensis) are frequently in an anhydrobiotic state, with unhatched nematode persisting for extended periods of time inside the cyst in the absence of the host. This paper shows fundamental changes in the response of quiescent and diapaused eggs of G. pallida to hydration and following exposure to tomato root diffusate (RD) using microarray gene expression analysis encompassing a broad set of genes. For the quiescent eggs, 547 genes showed differential expression following hydration vs. hydratation and RD (H-RD) treatment whereas 708 genes showed differential regulation for the diapaused eggs following these treatments. The comparison between hydrated quiescent and diapaused eggs showed marked differences, with 2,380 genes that were differentially regulated compared with 987 genes following H-RD. Hydrated quiescent and diapaused eggs were markedly different indicating differences in adaptation for long-term survival. Transport activity is highly up-regulated following H-RD and few genes were coincident between both kinds of eggs. With the quiescent eggs, the majority of genes were related to ion transport (mainly sodium), while the diapaused eggs showed a major diversity of transporters (amino acid transport, ion transport, acetylcholine or other molecules).Publisher PDFPeer reviewe

    A Mammal-Specific Doublesex Homolog Associates with Male Sex Chromatin and Is Required for Male Meiosis

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    Gametogenesis is a sexually dimorphic process requiring profound differences in germ cell differentiation between the sexes. In mammals, the presence of heteromorphic sex chromosomes in males creates additional sex-specific challenges, including incomplete X and Y pairing during meiotic prophase. This triggers formation of a heterochromatin domain, the XY body. The XY body disassembles after prophase, but specialized sex chromatin persists, with further modification, through meiosis. Here, we investigate the function of DMRT7, a mammal-specific protein related to the invertebrate sexual regulators Doublesex and MAB-3. We find that DMRT7 preferentially localizes to the XY body in the pachytene stage of meiotic prophase and is required for male meiosis. In Dmrt7 mutants, meiotic pairing and recombination appear normal, and a transcriptionally silenced XY body with appropriate chromatin marks is formed, but most germ cells undergo apoptosis during pachynema. A minority of mutant cells can progress to diplonema, but many of these escaping cells have abnormal sex chromatin lacking histone H3K9 di- and trimethylation and heterochromatin protein 1Ī² accumulation, modifications that normally occur between pachynema and diplonema. Based on the localization of DMRT7 to the XY body and the sex chromatin defects observed in Dmrt7 mutants, we conclude that DMRT7 plays a role in the sex chromatin transformation that occurs between pachynema and diplonema. We suggest that DMRT7 may help control the transition from meiotic sex chromosome inactivation to postmeiotic sex chromatin in males. In addition, because it is found in all branches of mammals, but not in other vertebrates, Dmrt7 may shed light on evolution of meiosis and of sex chromatin
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