307 research outputs found

    Spectroscopic Behavior of Composite, Black Thermal Paint, Solar Cell, and Multi-Layered Insulation Materials in a GEO Simulated Environment

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    The population of objects orbiting Earth is dominated by orbital debris. The following study presents reflectance spectroscopic measurements and bidirectional reflectance distribution function (BRDF) evaluations taken on common spacecraft materials (Table 1), some of which are likely candidates in the orbital debris population. Their optical properties were assessed in their pristine conditions, as well as after exposure in a space environmental chamber used to simulate space weathering. The materials studied will prove that they have excellent properties in resisting the effects of damage that are common in both low Earth orbit and geosynchronous Earth orbit (GEO) based on the research discussed in this work

    Spectroscopic Behavior of Composite, Black Thermal Paint, Solar Cell, and Multi-layered Insulation Materials in a GEO Simulated Environment

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    Materials currently populating Earth orbital regimes can be distinguished by comparing remote observational data to that of optical material measurements obtained in the laboratory. Experimentation for this research primarily involved the acquisition of spectroscopic measurements on materials of interest to the telescopic observational community for enhanced space situational awareness. Common spacecraft materials worthy of preeminent analysis for this investigation include a carbon-carbon (c-c) matrix composite, various black thermal paints, a GPS solar cell and three different cover glass components. These materials were subjected to a simulated geosynchronous Earth orbit (GEO) space environment with the intent of observing material optical property behavior over quantitative exposure time. The aforementioned materials have been measured in their pristine and GEO simulated exposed conditions. A reflectance spectrometer and a bi-directional reflectance distribution function (BRDF) optical system have been operated to perform material characterization, optical property analysis, and to further compare such data to telescopic observational data acquired on equal materials

    A Collaborative International Research Program on the Coupled North Atlantic-Arctic System: Science Plan

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    This North Atlantic-Arctic science plan is derived from an international workshop held in April 2014 with support from the National Science Foundation Division of Ocean Sciences and the European Union (EU). The workshop was designed to facilitate development of a core vision for advancing the next phase of research on the North Atlantic-Arctic system and strengthening international collaborations within and between the EU and North America

    The Effects of Alcohol on Self-Regulation of Sexual Arousal in Sexually Compulsive Men Who Have Sex with Men

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    Individuals who meet criteria for sexual compulsivity tend to be more likely to engage in behaviors that may have negative consequences. Despite the clear public health relevance, however, little is known about the determinants of sexual compulsivity. This psychophysiological study examined self-regulation of sexual arousal in men high and low in sexual compulsivity, when sober and after alcohol consumption. A total of 43 men who have sex with men (MSM) participated and were presented with a series of erotic film clips. Two clips were presented after alcohol consumption (BAL .06), two other film clips were viewed when sober. Within alcohol conditions, one of the two films was combined with a suppression, the other with a no-suppression instruction. Genital responses were lower in the high sexual compulsivity group and higher during no-suppression conditions. The suppression instruction was not effective under sober conditions but impacted responses after alcohol consumption. This effect was more pronounced for the low compulsivity group. The findings suggest that sexually compulsive men are less successful in inhibiting their sexual responses, but only after alcohol consumption. The findings also suggest that sexually compulsive men may be less responsive to (researcher-selected) erotic stimuli

    Lack of Correlation of WAIS Digit Span with Clox 1 and the Dementia Rating Scale in MCI

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    Individuals with MCI declined in performance over 6 months in the Clock-drawing (Clox 1) and the WAIS Digit Span tests, but not in the Dementia Rating Scale (DRS). Individual performance on Clox 1 and Digit Span did not correlate after 6 months. Performance on the Digit Span Test also did not correlate with the DRS, but performance on Clox 1 correlated with the DRS. Performance in Clox 1 was, therefore, not a predictor of performance in the Digit Span Test. These findings support the use of a test battery containing the Digit Span test to detect and track cognitive decline in MCI

    MARCH1 protects the lipid raft and tetraspanin web from MHCII proteotoxicity in dendritic cells

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    Dendritic cells (DCs) produce major histocompatibility complex II (MHCII) in large amounts to function as professional antigen presenting cells. Paradoxically, DCs also ubiquitinate and degrade MHCII in a constitutive manner. Mice deficient in the MHCII-ubiquitinating enzyme membrane-anchored RING-CH1, or the ubiquitin-acceptor lysine of MHCII, exhibit a substantial reduction in the number of regulatory T (Treg) cells, but the underlying mechanism was unclear. Here we report that ubiquitin-dependent MHCII turnover is critical to maintain homeostasis of lipid rafts and the tetraspanin web in DCs. Lack of MHCII ubiquitination results in the accumulation of excessive quantities of MHCII in the plasma membrane, and the resulting disruption to lipid rafts and the tetraspanin web leads to significant impairment in the ability of DCs to engage and activate thymocytes for Treg cell differentiation. Thus, ubiquitin-dependent MHCII turnover represents a novel quality-control mechanism by which DCs maintain homeostasis of membrane domains that support DC's Treg cell-selecting function

    Characterization of 14 polymorphic microsatellite loci developed for an Afrotherian species endemic to southern Africa, Elephantulus myurus (Macroscelidea : Macroscelididae)

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    Fourteen microsatellite loci were developed for the eastern rock sengi, Elephantulus myurus Thomas & Schwann, 1906 by incorporating genetic diversity from across its range in South Africa. Sengis are small mammals belonging to the order Macroscelidea, which comprises 19 species, all of which are endemic to Africa. The loci were amplified in 66 individuals from six localities. An average of 10.5 alleles per locus were identified, with observed and expected heterozygosity values ranging from 0.081 – 0.909 and 0.484 – 0.885, respectively. We also investigated cross-species amplification within the family and found variation in amplification success for five different species. The preliminary results from these amplification efforts could aid further studies into aspects of species diversity and biology. The markers described here represent the first set of variable nuclear markers for the genus Elephantulus, and, together with a set of 8 recently developed markers for Rhynchocyon petersi, Bocage 1880, the first markers for the Order Macroscelidea.National Research Foundation of South Africa (BvV), the University of Johannesburg and the DST-NRF SARChi Chair of Behavioural Ecology and Physiology (NCB). Electrophoresis of microsatellite markers was done at the Analytical Facility based at Stellenbosch University.http://link.springer.com/journal/133552018-02-27hb2016Zoology and Entomolog

    Genome-wide Characterization of Shared and Distinct Genetic Components that Influence Blood Lipid Levels in Ethnically Diverse Human Populations

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    Blood lipid concentrations are heritable risk factors associated with atherosclerosis and cardiovascular diseases. Lipid traits exhibit considerable variation among populations of distinct ancestral origin as well as between individuals within a population. We performed association analyses to identify genetic loci influencing lipid concentrations in African American and Hispanic American women in the Women’s Health Initiative SNP Health Association Resource. We validated one African-specific high-density lipoprotein cholesterol locus at CD36 as well as 14 known lipid loci that have been previously implicated in studies of European populations. Moreover, we demonstrate striking similarities in genetic architecture (loci influencing the trait, direction and magnitude of genetic effects, and proportions of phenotypic variation explained) of lipid traits across populations. In particular, we found that a disproportionate fraction of lipid variation in African Americans and Hispanic Americans can be attributed to genomic loci exhibiting statistical evidence of association in Europeans, even though the precise genes and variants remain unknown. At the same time, we found substantial allelic heterogeneity within shared loci, characterized both by population-specific rare variants and variants shared among multiple populations that occur at disparate frequencies. The allelic heterogeneity emphasizes the importance of including diverse populations in future genetic association studies of complex traits such as lipids; furthermore, the overlap in lipid loci across populations of diverse ancestral origin argues that additional knowledge can be gleaned from multiple populations
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