933 research outputs found

    High Power Microwave (HPM) and Ionizing Radiation Effects on CMOS Devices

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    Integrated circuits (ICs) are inherently complicated and made worse by increasing transistor quantity and density. This trend potentially enhances concomitant effects of high energy radiation and local or impressed electromagnetic interference (EMI). The reduced margin for signal error may counter any gain in radiation hardness from smaller device dimensions. Isolated EMI and ionizing radiation studies on circuits have been conducted extensively over the past 30 years. However, little focus has been placed on the combined effects. To investigate the effect of combined EMI and ionizing radiation, two complementary metal oxide semiconductor (CMOS) inverter technologies (CD4069 and SN74AUC1G04) were analyzed for their static performance in response to EMI and up to 146 kRad (tissue) gamma radiation. The combined EMI and gamma radiation environment, compared to the isolated effects, produced the most severe degradation in inverter performance for both device technologies

    Infrared and Raman spectroscopic studies of structural variations in minerals from Apollo 11, 12, 14 and 15 samples, volume 3

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    Infrared and Raman vibrational spectroscopic data, yielding direct information on molecular structure, were obtained for single grains ( 150 microns) of minerals, basalts, and glasses isolated from Apollo 11, 12, 14, and 15 rock and dust samples, and for grains in Apollo 14 polished butt samples. From the vibrational data, specification substitutions were determined for the predominant silicate minerals of plagioclase, pyroxene, and olivine. Unique spectral variations for grains of K-feldspar, orthopyroxene, pyroxenoid, and ilmenite were observed to exceed the ranges of terrestrial samples, and these variations may be correlatable with formation histories. Alpha-quartz was isolated as pure single grains, in granitic grains composited with sanidine, and in unique grains that were intimately mixed with varying amounts of glass. Accessory minerals of chromite and ulvospinel were isolated as pure grains and structurally characterized from their distinctive infrared spectra. Fundamental vibrations of the SiO4 tetrahedra in silicate minerals were used to classify bulk compositions in dust sieved fractions, basalt grains and glass particles, and to compare modal characteristics for maria, highland and rille samples. No hydrated minerals were found in any of the samples studied, indicating anhydrous formation conditions

    Antagonistic and cooperative AGO2-PUM interactions in regulating mRNAs.

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    Approximately 1500 RNA-binding proteins (RBPs) profoundly impact mammalian cellular function by controlling distinct sets of transcripts, often using sequence-specific binding to 3' untranslated regions (UTRs) to regulate mRNA stability and translation. Aside from their individual effects, higher-order combinatorial interactions between RBPs on specific mRNAs have been proposed to underpin the regulatory network. To assess the extent of such co-regulatory control, we took a global experimental approach followed by targeted validation to examine interactions between two well-characterized and highly conserved RBPs, Argonaute2 (AGO2) and Pumilio (PUM1 and PUM2). Transcriptome-wide changes in AGO2-mRNA binding upon PUM knockdown were quantified by CLIP-seq, and the presence of PUM binding on the same 3'UTR corresponded with cooperative and antagonistic effects on AGO2 occupancy. In addition, PUM binding sites that overlap with AGO2 showed differential, weakened binding profiles upon abrogation of AGO2 association, indicative of cooperative interactions. In luciferase reporter validation of candidate 3'UTR sites where AGO2 and PUM colocalized, three sites were identified to host antagonistic interactions, where PUM counteracts miRNA-guided repression. Interestingly, the binding sites for the two proteins are too far for potential antagonism due to steric hindrance, suggesting an alternate mechanism. Our data experimentally confirms the combinatorial regulatory model and indicates that the mostly repressive PUM proteins can change their behavior in a context-dependent manner. Overall, the approach underscores the importance of further elucidation of complex interactions between RBPs and their transcriptome-wide extent

    Cas Adaptor Proteins Coordinate Sensory Axon Fasciculation.

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    Development of complex neural circuits like the peripheral somatosensory system requires intricate mechanisms to ensure axons make proper connections. While much is known about ligand-receptor pairs required for dorsal root ganglion (DRG) axon guidance, very little is known about the cytoplasmic effectors that mediate cellular responses triggered by these guidance cues. Here we show that members of the Cas family of cytoplasmic signaling adaptors are highly phosphorylated in central projections of the DRG as they enter the spinal cord. Furthermore, we provide genetic evidence that Cas proteins regulate fasciculation of DRG sensory projections. These data establish an evolutionarily conserved requirement for Cas adaptor proteins during peripheral nervous system axon pathfinding. They also provide insight into the interplay between axonal fasciculation and adhesion to the substrate

    Exploring Faculty Dispositions When Long-Term Contracts Are Offered Instead of Tenure Across an Institution

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    This article examines faculty job security and satisfaction at a burgeoning public college that offers faculty long-term contracts for the ranks of assistant, associate, and full professor, but does not offer tenure to any faculty. Through focus groups, interviews, and a survey of over 100 faculty, we find that promotion in conjunction with long-term contracts at this non-tenure-granting institution offers faculty moderate levels of job security and satisfaction, particularly for men. Promotion may have different effects on security and satisfaction, depending on gender and the degree to which the respondents believe they understand their contract. Since the faculty’s contract satisfaction is associated with their perceived understanding of its terms, we argue that it is important that those terms be transparent at this institution and others that may implement a similar long-term contract structure

    Localization of complement factor H gene expression and protein distribution in the mouse outer retina.

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    To determine the localization of complement factor H (Cfh) mRNA and its protein in the mouse outer retina.Quantitative real-time PCR (qPCR) was used to determine the expression of Cfh and Cfh-related (Cfhr) transcripts in the RPE/choroid. In situ hybridization (ISH) was performed using the novel RNAscope 2.0 FFPE assay to localize the expression of Cfh mRNA in the mouse outer retina. Immunohistochemistry (IHC) was used to localize Cfh protein expression, and western blots were used to characterize CFH antibodies used for IHC.Cfh and Cfhr2 transcripts were detected in the mouse RPE/choroid using qPCR, while Cfhr1, Cfhr3, and Cfhrc (Gm4788) were not detected. ISH showed abundant Cfh mRNA in the RPE of all mouse strains (C57BL/6, BALB/c, 129/Sv) tested, with the exception of the Cfh(-/-) eye. Surprisingly, the Cfh protein was detected by immunohistochemistry in photoreceptors rather than in RPE cells. The specificity of the CFH antibodies was tested by western blotting. Our CFH antibodies recognized purified mouse Cfh protein, serum Cfh protein in wild-type C57BL/6, BALB/c, and 129/Sv, and showed an absence of the Cfh protein in the serum of Cfh(-/-) mice. Greatly reduced Cfh protein immunohistological signals in the Cfh(-/-) eyes also supported the specificity of the Cfh protein distribution results.Only Cfh and Cfhr2 genes are expressed in the mouse outer retina. Only Cfh mRNA was detected in the RPE, but no protein. We hypothesize that the steady-state concentration of Cfh protein is low in the cells due to secretion, and therefore is below the detection level for IHC

    Galerkin and Runge–Kutta methods: unified formulation, a posteriori error estimates and nodal superconvergence

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    Abstract. We unify the formulation and analysis of Galerkin and Runge–Kutta methods for the time discretization of parabolic equations. This, together with the concept of reconstruction of the approximate solutions, allows us to establish a posteriori superconvergence estimates for the error at the nodes for all methods. 1

    Marine Biodiversity and Ecosystem Health of Ilhas Selvagens, Portugal

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    In September 2015, National Geographic's Pristine Seas project, in conjunction with the Instituto Universitário-Portugal, The Waitt Institute, the University of Western Australia, and partners conducted a comprehensive assessment of the rarely surveyed Ilhas Selvagens to explore the marine environment, especially the poorly understood deep sea and open ocean areas, and quantify the biodiversity of the nearshore marine environment
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