535 research outputs found

    An assessment of twilight airglow inversion procedures using atmosphere explorer observations

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    The aim of this research project was to test and truth some recently developed methods for recovering thermospheric oxygen atom densities and thermospheric temperatures from ground-based observations of the 7320 A O(+)((sup 2)D - (sup 2)P) twilight air glow emission. The research plan was to use twilight observations made by the Visible Airglow Experiment (VAE) on the Atmosphere Explorer 'E' satellite as proxy ground based twilight observations. These observations were to be processed using the twilight inversion procedures, and the recovered oxygen atom densities and thermospheric temperatures were then to be examined to see how they compared with the densities and temperatures that were measured by the Open Source Mass Spectrometer and the Neutral Atmosphere Temperature Experiment on the satellite

    Slow early growers have more muscle in relation to adult activity: evidence from Cebu, Philippines

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    Adult skeletal muscle mass (SMM) protects against type 2 diabetes but little is known about its developmental antecedents. We examined whether pace of early weight gain predicted adult SMM in a birth cohort from Cebu City, Philippines. Additionally, we examined whether increases in SMM associated with adult muscle-building exercise varied according to early growth

    The Roles of Vertical Advection and Eddy Diffusion in the Equatorial Mesospheric Semi-Annual Oscillation (MSAO)

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    Observations of the mesospheric semi-annual oscillation (MSAO) in the equatorial region have been reported dating back several decades. Seasonal variations in both species densities and airglow emissions are well documented. The extensive observations available offer an excellent case study for comparison with model simulations. A broad range of MSAO measurements is summarised with emphasis on the 80-100 km region. The objective here is not to address directly the complicated driving forces of the MSAO, but rather to employ a combination of observations and model simulations to estimate the limits of some of the underlying dynamical processes. Photochemical model simulations are included for near-equinox and near-solstice conditions, the two times with notable differences in the observed MSAO parameters. Diurnal tides are incorporated in the model to facilitate comparisons of observations made at different local times. The roles of water vapour as the driver species and ozone as the response species are examined to test for consistency between the model results and observations. The simulations suggest the interactions between vertical eddy diffusion and background vertical advection play a significant role in the MSAO phenomenon. Further, the simulations imply there are rigid limits on vertical advection rates and eddy diffusion rates. For August at the Equator, 90 km altitude, the derived eddy diffusion rate is approximately 1 x 106 cm2 s-1 and the vertical advection is upwards at 0.8 cm s-1. For April the corresponding values are 4 x 105 cm2 s-1 and 0.1 cm s-1. These results from the current 1-D model simulations will need to be verified by a full 3-D simulation. Exactly how vertical advection and eddy diffusion are related to gravity wave momentum as discussed by Dunkerton (1982) three decades ago remains to be addressed

    Gallin; an antimicrobial peptide member of a new avian defensin family, the ovodefensins, has been subject to recent gene duplication

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    Background: Egg white must provide nutrients and protection to the developing avian embryo. One way in which this is achieved is an arsenal of antimicrobial proteins and peptides which are essentially extensions of the innate immune system. Gallin is a recently identified member of a family of peptides that are found in egg white. The function of this peptide family has not been identified and they are potentially antimicrobial. Results: We have confirmed that there are at least 3 forms of the gallin gene in the chicken genome in 3 separate lines of chicken, all the forms are expressed in the tubular cells of the magnum region of the oviduct, consistent with its presence in egg white. mRNA expression levels are in the order 10,000 times greater in the magnum than the shell gland. The conservation between the multiple forms of gallin in the chicken genome compared with the conservation between gallin and other avian gallin like peptides, suggests that the gene duplication has occurred relatively recently in the chicken lineage. The gallin peptide family contains a six cysteine motif (C-X-5-C-X-3-C-X-11-CX3-C-C) found in all defensins, and is most closely related to avian beta-defensins, although the cysteine spacing differs. Further support for the classification comes from the presence of a glycine at position 10 in the 41 amino acid peptide. Recombinant gallin inhibited the growth of Escherischia coli (E. coli) at a concentration of 0.25 mu M confirming it as part of the antimicrobial innate immune system in avian species. Conclusions: The relatively recent evolution of multiple forms of a member of a new defensin related group of peptides that we have termed ovodefensins, may be an adaptation to increase expression or the first steps in divergent evolution of the gene in chickens. The potent antimicrobial activity of the peptide against E. coli increases our understanding of the antimicrobial strategies of the avian innate immune system particularly those of the egg white and the evolution of the defensin family. The potential of this peptide and others in the family can now be investigated in a number of novel antimicrobial role

    Flying Squirrel–associated Typhus, United States

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    In March 2002, typhus fever was diagnosed in two patients residing in West Virginia and Georgia. Both patients were hospitalized with severe febrile illnesses, and both had been recently exposed to or had physical contact with flying squirrels or flying squirrel nests. Laboratory results indicated Rickettsia prowazekii infection

    Moving beyond a snapshot to understand changes in the well-being of native Amazonians : panel evidence (2002-2006) from Bolivia

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    Forces such as the opening of trade, globalization, multinational corporate resource extraction, urbanization, acculturation, and colonization catalyze economic, ecological, and sociocultural change, which can threaten the well-being and habitat of native Amazonians. Understanding these forces is of paramount importance to improve the well-being of native Amazonians and to foster the conservation of biological diversity, yet most analyses of these forces rely on cross-sectional data. Though adequate to describe the association between variables at one point in time, cross-sectional data do not allow one to estimate changes in well-being over time. We collected data annually during five consecutive years (2002-2006, inclusive) from a foraging and farming society of native Amazonians in Bolivia (Tsimane') to estimate annual rates of change for seven indicators of adult well-being. Indicators encompassed both objective and subjective measures of well-being that included economic, health, psychological, and social dimensions that overlap well with Tsimane' notions of well-being. The annual rate of change in the inflation-adjusted (hereafter real) value of food consumption (+6.35%), body mass index (+0.71%), and incidence of anger (−10.40%) show significant improvements over time, but the annual rate of change in the self-reported number of recent ailments (+7.35%) shows a significant deterioration. Trends in other indicators of well-being (smiles, real wealth, social relations) show positive but insignificant rates of change. Results did not vary by sex and were consistent when using other indicators of well-bein
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