4,176 research outputs found

    Electronic magnification for astronomical camera tubes

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    Definitions, test schemes, and analyses used to provide variable magnification in the image section of the television sensor for large space telescopes are outlined. Experimental results show a definite form of magnetic field distribution is necessary to achieve magnification in the range 3X to 4X. Coil systems to establish the required field shapes were built, and both image intensifiers and camera tubes were operated at high magnification. The experiments confirm that such operation is practical and can provide satisfactory image quality. The main problem with such a system was identified as heating of the photocathode due to concentration of coil power dissipation in that vicinity. Suggestions for overcoming this disadvantage are included

    An Outcome-Based Competency Model for Systems Engineering Trainees

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    Dominant theories relating to outcome-based learning and workforce competency were synthesized into a singular outcome-based competency model to evaluate systems engineering training. A baseline model was developed using leading theories from the academic literature pertaining to competencies for systems engineers across three categories: cognitive, skill-based, and behavioral. The model was further refined via qualitative and quantitative analysis of formal interviews of subject matter experts in the field of systems engineering workforce management. The refined model classifies 28 critical competencies for systems engineers into three tiers of workforce functionality: foundational, specialized, and leadership. The resultant theoretical model is both grounded in robust theory and is validated by subject matter experts and is suitable to drive practical evaluations of systems engineering training programs

    Omówienie problemu właściwej interpretacji kariotypu molekularnego przy próbie identyfikacji obserwowanych niezrównoważonych aberracji chromosomowych u pacjentów z niespecyficzną niepełnosprawnością intelektualną oraz zespołem mnogich wad wrodzonych

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    Ocena kariotypu pacjenta stanowi podstawę prawidłowej porady genetycznej mającej związek z podjętym leczeniem i/lub prewencją. W chwili obecnej laboratoria cytogenetyczne mają do dyspozycji ogromną liczbę metod diagnostycznych, w tym analizy kariotypu molekularnego oparteb na metodach CGH. Metody CGH pozwalają na wykrywanie zmian zdecydowanie mniejszych, w porównaniu z klasycznymi technikami cytogenetycznymi takimi jak metoda GTG. Niestety, brak możliwości bezpośredniej analizy chromosomów pacjenta może prowadzić do przekłamania podczas interpretacji wyniku. W poniższym opracowaniu przedstawiono dwa przypadki obrazujące najczęstsze problemy pojawiające się podczas i nterpretacji wyników kariotypu molekularnego metodą CGH.Evaluation of the patient's karyotype is the basis for proper genetic counseling, and thus also for a treatment or prevention to be taken. At present, cytogenetic laboratories have at their disposal a large number of diagnostic methods, including molecular karyotype analysis based on CGH procedures. The CGH methods allow to detect much smaller changes than conventional cytogenetic techniques such as a GTG method. Unfortunately, lack of direct analysis of patient's chromosomes may lead to a distortion in interpreting the result. The following paper presents two cases illustrating the most common problems in interpreting the results of molecular karyotyping using the CGH procedure

    Tau and muon pair production cross-sections in electron-positron annihilations at sqrt{s} = 10.58 GeV

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    The calculational precision of \ee\to\tautau and \ee\to\mumu production cross-sections in electron-positron annihilations at \roots = 10.58 \gev are studied for the \kk Monte Carlo simulation program. We determine \sigma(\ee\to\tautau) = (0.919 \pm 0.003) \nb and \sigma(\ee\to\mumu) = (1.147 \pm 0.005) \nb, where the error represents the precision of the calculation.Comment: 7 pages, 3 tables, 1 figure (published in Physical Review D 77, 054012 (2008)

    Anion exchange separations of metal ions in partially nonaqueous solutions

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    A systematic approach to anion exchange in partially nonaqueous solvents was initiated. Distribution coefficients of metal ions for Dowex 1 X8, chloride form resin in organic solvent-water mixtures containing hydrochloric acid were measured. The organic solvents used were methyl alcohol, ethyl alcohol, isopropyl alcohol, acetone, and dioxane

    Studies on bridging tractions - simultaneous bridging tractions and COD measurements

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    The main objective of this work is to investigate the bridging tractions in a model composite using optical fiber Bragg grating (FBG) sensors written into selected reinforcing fibers. Simultaneously, the crack opening displacement (COD) is measured using a speckle interferometry technique. The measurements are useful in the verification of the relation between the COD and bridging tractions established with the use of the weight function method. Center crack specimens made of epoxy and reinforced with one layer of optical fibers are prepared and tested under remote tension parallel to the fibers. Bragg gratings of 0.17 to 0.38mm in length are introduced in selected fibers for direct, non invasive, local measurements of axial strains in these fibers. A controlled central crack, bridged by intact fibers, is introduced by a laser technique such that the FBGs are located between the crack faces. The results on the forces obtained from the FBGs and the COD-weight function method show good agreement. The experimental results also compare very well with 3-dimensional numerical simulations of the actual specimen geometry and loading configuratio

    MTRNR2L12 : a candidate blood marker of early Alzheimer's disease-like dementia in adults with Down Syndrome

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    Morphological abnormalities observed typically in the brains of adults with Down syndrome are identical with those present in patients with Alzheimer’s disease. However, only some adults with Down syndrome suffer from early dementia, whereas others remain unaffected. We aimed to identify the genomic background responsible for this observation. We performed cognitive assessment and genome expression analysis of blood mononuclear cells in seniors with Down syndrome. Unaffected elderly patients and younger patients with severe cognitive disability or cognitive deterioration differed significantly with regard to the MTRNR2L12 gene. Our findings suggest the potential value of this gene as a blood marker of early dementia in individuals with Down syndrome
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