1,370 research outputs found

    Space Experiment on Tuber Development and Starch Accumulation for CELSS

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    Potato explants (leaf, small stem section, and axillary bud), flown on STS-73, developed tubers of 1.5 cm diameter and 1.7 g mass during the 16 day period of spaceflight. The experiment was undertaken in the ASTROCULTURE(Trademark) experiment package under controlled temperature, humidity, lighting, and carbon dioxide concentrations. The tubers formed in the explant system under microgravity had the same gross morphology, the same anatomical configuration of cells and tissues, and the same sizes, shapes, and surface character of starch granules as tubers formed in a 1 g environment. The total accumulation of starch and other energy containing compounds was singular in space flight and ground control tubers. Enzyme activity of starch synthase, starch phosphorylase, and total hydrolase was similar in spaceflight and ground controls but activity of ADP-glucose pyrophosphorylase was reduced in the spaceflight tuber tissue. This experiment documented that potatoes will metabolize and accumulate starch as effectively in spaceflight as on the ground and thus this data provides the potential for effective utilization of potatoes in life support systems of space bases

    A low-temperature phase of bis(tetrabutylammonium) octa-l3-chloridohexachlorido- octahedro-hexatungstate

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    The article discusses the low-temperature phase of bis(tetrabutylammonium) octa-µ3-chlorido-hexachlorido-octahedro-hexa-tungstate, which undergoes a reversible phase transition at 268 K. The unit cells of the room- and low-temperature polymorphs of this compound are found to be closely related. The hydrocarbon chain of one of the tetrabutylammonium cations is found to be disordered at both 150 and 200 K

    Inequalities in health complaints: 20-year trends among adolescents in Scotland, 1998–2018

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    This study examined trends in inequalities in health complaints among early adolescents in Scotland from 1998 to 2018. We analysed data from the Health Behaviour in School-aged Children (HBSC) survey conducted in Scotland in 1998, 2002, 2006, 2010, 2014 and 2018. A self-report questionnaire was administered in schools to a nationally representative sample of 11-, 13-, and 15-year-olds (n = 29,250). Health complaints were measured using a scale comprising four psychological symptoms (feeling low, feeling nervous, irritability and sleep difficulties) and four somatic symptoms (headache, backache, stomachache and dizziness). Socio-economic status was measured using the Family Affluence Scale. Between 1998 and 2018, there were significant increases in the proportion of girls and boys reporting feeling low, feeling nervous, sleep difficulties and backache. Prevalence of the eight individual health complaints was higher among girls and adolescents from lower affluence families. Socio-economic inequalities increased over time, such that declines in mental health were greatest among low affluence adolescents. The data show worsening trends in health complaints among Scottish adolescents between 1998 and 2018, particularly for girls and adolescents from low affluence families. Increasing inequalities in mental health highlight the need to address the underlying social and structural determinants of adolescent mental health

    Islands of linkage in an ocean of pervasive recombination reveals two-speed evolution of human cytomegalovirus genomes

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    Human cytomegalovirus (HCMV) infects most of the population worldwide, persisting throughout the host's life in a latent state with periodic episodes of reactivation. While typically asymptomatic, HCMV can cause fatal disease among congenitally infected infants and immunocompromised patients. These clinical issues are compounded by the emergence of antiviral resistance and the absence of an effective vaccine, the development of which is likely complicated by the numerous immune evasins encoded by HCMV to counter the host's adaptive immune responses, a feature that facilitates frequent super-infections. Understanding the evolutionary dynamics of HCMV is essential for the development of effective new drugs and vaccines. By comparing viral genomes from uncultivated or low-passaged clinical samples of diverse origins, we observe evidence of frequent homologous recombination events, both recent and ancient, and no structure of HCMV genetic diversity at the whole-genome scale. Analysis of individual gene-scale loci reveals a striking dichotomy: while most of the genome is highly conserved, recombines essentially freely and has evolved under purifying selection, 21 genes display extreme diversity, structured into distinct genotypes that do not recombine with each other. Most of these hyper-variable genes encode glycoproteins involved in cell entry or escape of host immunity. Evidence that half of them have diverged through episodes of intense positive selection suggests that rapid evolution of hyper-variable loci is likely driven by interactions with host immunity. It appears that this process is enabled by recombination unlinking hyper-variable loci from strongly constrained neighboring sites. It is conceivable that viral mechanisms facilitating super-infection have evolved to promote recombination between diverged genotypes, allowing the virus to continuously diversify at key loci to escape immune detection, while maintaining a genome optimally adapted to its asymptomatic infectious lifecycle

    Microwave Gaseous Discharges

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    Contains research objectives and reports on three research projects.Atomic Energy Commission under Contract AT(30-1)184

    (+)-(1S,5R,10S)-11,11-Dimeth­yl-4-oxa­tricyclo­[8.4.0.01,5]tetra­deca­ne-3,12-dione

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    The title compound, C15H22O3, was prepared via amino-acid-promoted Robinson annulation followed by tandem Pd/C-mediated hydrogenation and oxidative cyclization. This product was instrumental in determining the feasibility of a stereocontrolled hydrogenation in which the directing hydroxyl group is adjacent to the 6–7-ring network and its olefinic component. The asymmetric unit consists of a single mol­ecule with normal geometric parameters. The absolute configuration was assigned based on the known enanti­omeric prescursor. Inter­molecular C—H⋯O inter­actions link each mol­ecule with four neighboring mol­ecules

    Racial Differences in Neighborhood Perceptions and their Influences on Physical Activity among Urban Older Women

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    Background: Proper levels of physical activity (PA) are important to healthy aging. Little is known about racial differences in influences of neighborhood perceptions (NP) on PA and use of neighborhood resources among community-dwelling older women. Materials and methods: In 2014 and 2015, 49 white and 44 black women of age 65 and older living in Washington, DC were queried about their PA, NP, use of neighborhood resources and sociodemographic characteristics. They wore an accelerometer and a Global Positioning System device concurrently for 7 consecutive days. Data were analyzed by race. Results: Compared to Whites, Blacks had lower NP scores (71% positive vs. 77%, p = 0.01), lower mean daily step counts (mean (SD): 3256 (1918) vs. 5457 (2989), p \u3c 0.001), and lower frequencies of all exercise activities combined (19.7 (8.7) vs. 25.2 (11.8) per week, p = 0.01). For both Whites and Blacks, better NPs were associated with more frequent PA both at (p = 0.05) and away from home (p = 0.01). However, better NPs were associated with higher frequencies of exercise activities, moderate-to-high intensity activities, and utilitarian walking for Whites but not Blacks (p \u3c 0.05 for race-perception interaction terms). Conclusions: In an urban setting, older Black women were more likely than older White women to have poor NPs, less PA, and weaker or no association of positive NPs with higher levels of certain PAs. Such substantial racial differences warrant further investigation and consideration in health promotion programs
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