5,663 research outputs found

    A catalog of radio observations of Jupiter 1961-1964

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    Catalog of radio observations of Jupiter 1961 to 196

    The 1983 Goddard Space Flight Center Battery Workshop

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    Subjects covered included advanced energy storage programs, lithium cell technology, nickel cadmium technology, testing and flight experience and metal hydrogen technology

    Enhanced hydrogen storage in Ni/Ce composite oxides

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    The properties of dried (but not calcined) coprecipitated nickel ceria systems have been investigated in terms of their hydrogen emission characteristics following activation in hydrogen. XRD and BET data obtained on the powders show similarities to calcined ceria but it is likely that the majority of the material produced by the coprecipitation process is largely of an amorphous nature. XPS data indicate very little nickel is present on the outermost surface of the particles. Nevertheless, the thermal analytical techniques (TGA, DSC and TPD-MS) indicate that the hydrogen has access to the catalyst present and the nickel is able to generate hydrogen species capable of interacting with the support. Both unactivated and activated materials show two hydrogen emission features, viz. low temperature and high temperature emissions (LTE and HTE, respectively) over the temperature range 50 and 500 °C. A clear effect of hydrogen interaction with the material is that the activated sample not only emits much more hydrogen than the corresponding unactivated one but also at lower temperatures. H2 dissociation occurs on the reduced catalyst surface and the spillover mechanism transfers this active hydrogen into the ceria, possibly via the formation and migration of OH− species. The amount of hydrogen obtained (0.24 wt%) is 10× higher than those observed for calcined materials and would suggest that the amorphous phase plays a critical role in this process. The affiliated emissions of CO and CO2 with that of the HTE hydrogen (and consumption of water) strongly suggests a proportion of the hydrogen emission at this point arises from the water gas shift type reaction. It has not been possible from the present data to delineate between the various hydrogen storage mechanisms reported for ceria

    HIV-1 designed to use different tRNA(Gln )isoacceptors prefers to select tRNA(Thr )for replication

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    BACKGROUND: Previous studies have shown that infection with human immunodeficiency virus type 1 (HIV-1) causes acceleration of the synthesis of glutamine tRNA (tRNA(Gln)) in infected cells. To investigate whether this might influence HIV-1 to utilize tRNA(Gln )as a primer for initiation of reverse transcription, we have constructed HIV-1 proviral genomes in which the PBS and the A-loop region upstream of the PBS have been made complementary to either the anticodon region of tRNA(Gln,1 )or tRNA(Gln,3 )and 3' terminal 18 nucleotides of each isoacceptor of tRNA(Gln). RESULTS: Viruses in which the PBS was altered to be complementary to tRNA(Gln,1 )or tRNA(Gln,3 )with or without the A-loop all exhibited a lower infectivity than the wild type virus. Viruses with only the PBS complementary to tRNA(Gln,1 )or tRNA(Gln,3 )reverted to wild type following culture in SupT1 cells. Surprisingly, viruses in which the PBS and A-loop were complementary to tRNA(Gln,1 )did not grow in SupT1 cells, while viruses in which the PBS and A-loop were made complementary to tRNA(Gln,3 )grew slowly in SupT1 cells. Analysis of the PBS of this virus revealed that it had reverted to select tRNA(Thr )as the primer, which shares complementarity in 15 of 18 nucleotides with the PBS complementary to tRNA(Gln,3). CONCLUSION: The results of these studies support the concept that the HIV-1 has preferred tRNAs that can be selected as primers for replication

    HIV gene expression from intact proviruses positioned in bacterial artificial chromosomes at integration sites previously identified in latently infected T cells

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    AbstractHIV integration predominantly occurs in introns of transcriptionally active genes. To study the impact of the integration site on HIV gene expression, a complete HIV-1 provirus (with GFP as a fusion with Nef) was inserted into bacterial artificial chromosomes (BACs) at three sites previously identified in latent T cells of patients: topoisomerase II (Top2A), DNA methyltransferase 1 (DNMT1), or basic leucine transcription factor 2 (BACH2). Transfection of BAC-HIV into 293T cells resulted in a fourfold difference in production of infectious HIV-1. Cell lines were established that contained BAC–Top2A, BAC–DNMT1, or BAC–BACH2, but only BAC–DNMT1 spontaneously produced virus, albeit at a low level. Stimulation with TNF-α resulted in virus production from four of five BAC–Top2A and all BAC–DNMT1 cell lines, but not from the BAC–BACH2 lines. The results of these studies highlight differences between integration sites identified in latent T cells to support virus production and reactivation from latency

    Memory and comprehension for health information among older adults: distinguishing the effects of domain-general and domain-specific knowledge

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    While there is evidence that knowledge influences understanding of health information, less is known about the processing mechanisms underlying this effect and its impact on memory. We used the moving window paradigm to examine how older adults varying in domain-general crystallised ability (verbal ability) and health knowledge allocate attention to understand health and domain-general texts. Participants (n = 107, age: 60-88 years) read and recalled single sentences about hypertension and about non-health topics. Mixed-effects modelling of word-by-word reading times suggested that domain-general crystallised ability increased conceptual integration regardless of text domain, while health knowledge selectively increased resource allocation to conceptual integration at clause boundaries in health texts. These patterns of attentional allocation were related to subsequent recall performance. Although older adults with lower levels of crystallised ability were less likely to engage in integrative processing, when they did, this strategy had a compensatory effect in improving recall. These findings suggest that semantic integration during reading is an important comprehension process that supports the construction of the memory representation and is engendered by knowledge. Implications of the findings for theories of text processing and memory as well as for designing patient education materials are discussed

    Induction of hepatic synthesis of serum amyloid A protein and actin.

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    No effect of 14 day consumption of whole grain diet compared to refined grain diet on antioxidant measures in healthy, young subjects: a pilot study

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    <p>Abstract</p> <p>Background</p> <p>Epidemiological evidence supports that a diet high in whole grains is associated with lowered risk of chronic diseases included coronary heart disease, obesity, type 2 diabetes, and some types of cancer. One potential mechanism for the protective properties of whole grains is their antioxidant content. The aim of this study was to compare differences in antioxidant measures when subjects consumed either refined or whole grain diets.</p> <p>Methods</p> <p>Twenty healthy subjects took part in a randomized, crossover dietary intervention study. Subjects consumed either a refined grain or whole grain diet for 14 days and then the other diet for the next 14 days. Male subjects consumed 8 servings of grains per day and female subjects consumed 6 servings of grains per day. Blood and urine samples were collected at the end of each diet. Antioxidant measures included oxygen radical absorbance capacity (ORAC) in blood, and isoprostanes and thiobarbituric acid reactive substances (TBARS) in urine.</p> <p>Results</p> <p>The whole grain diet was significantly higher in dietary fiber, vitamin B6, folate, selenium, copper, zinc, iron, magnesium and cystine compared to the refined grain diet. Despite high intakes of whole grains, no significant differences were seen in any of the antioxidant measures between the refined and whole grain diets.</p> <p>Conclusions</p> <p>No differences in antioxidant measures were found when subjects consumed whole grain diets compared to refined grain diets.</p

    A Partial African Ancestry for the Creole Cattle Populations of the Caribbean

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    Seventy-eight cattle samples from three Creole Caribbean islands and one Brazilian breed were analyzed for sequence variation in the hypervariable segment of the mitochondrial DNA control region. Seventy-three samples displayed Bos taurus haplotypes, and five samples exhibited haplotypes that were of Bos indicus ancestry. Phylogenetic analysis revealed that all sampled B. taurus sequences fell into two distinct clusters with separate African and European origins. European sequences were encountered in each population; however, the distribution of African haplotypes was uneven, with the highest proportion of African influence found in the Guadeloupe Creole. The reduced levels of African haplotypic variation within the Caribbean and Brazilian are consistent with prior founder effects. Additionally, genetic variation at three microsatellite loci illustrated African influence uniquely in the Guadeloupe Creole. Collectively, the data suggest that this African influence is, at least in part, attributable to the historical importation of African cattle to the Americas. Furthermore, alleles of B. indicus ancestry were detected at appreciable frequencies in all Caribbean Creole populations and may reflect zebu introgressions from either West Africa or the Indian subcontinen
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