3,695 research outputs found

    Estimating stratospheric temperature trends using satellite microwave radiances

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    The objective was to evaluate and intercompare stratospheric temperatures using Microwave Sounding Unit (MSU) data as a basis data set. The MSU, aboard the NOAA polar orbiter satellite series, provides twice daily global coverage over a layer (50-150 mb) at approximately a (170km)(exp 2) resolution. Conventional data sets will be compared to the satellite data in the lower stratosphere in order to assess their quality for trend computations

    Strengthening the policy setting process for global malaria control and elimination

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    The scale-up of malaria control efforts in recent years, coupled with major investments in malaria research, has produced impressive public health impact in a number of countries and has led to the development of new tools and strategies aimed at further consolidating malaria control goals. As a result, there is a growing need for the malaria policy setting process to rapidly review increasing amounts of evidence

    Space-time thermodynamics and subsystem observables in a kinetically constrained model of glassy systems

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    In a recent article [M. Merolle et al., Proc. Natl. Acad. Sci. USA 102, 10837 (2005)] it was argued that dynamic heterogeneity in dd-dimensional glass formers is a manifestation of an order-disorder phenomenon in the d+1d+1 dimensions of spacetime. By considering a dynamical analogue of the free energy, evidence was found for phase coexistence between active and inactive regions of spacetime, and it was suggested that this phenomenon underlies the glass transition. Here we develop these ideas further by investigating in detail the one-dimensional Fredrickson-Andersen (FA) model in which the active and inactive phases originate in the reducibility of the dynamics. We illustrate the phase coexistence by considering the distributions of mesoscopic spacetime observables. We show how the analogy with phase coexistence can be strengthened by breaking microscopic reversibility in the FA model, leading to a non-equilibrium theory in the directed percolation universality class.Comment: 12 pages, 11 figures, final version with minor change

    Color and pigment polymorphisms of northern leopard frogs on a prairie landscape

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    Variation allows populations to adapt to changing conditions. As human activities continue to alter environments and evolutionary processes, it becomes increasingly important to conserve standing genetic variation. Despite technical advances in population genetics, it is still useful to have inexpensive methods of detecting and monitoring genetic variation, particularly in traits that potentially influence fitness. In the Northern Leopard Frog, Lithobates pipiens (= Rana pipiens), genetically determined color (green [dominant: G] or brown [recessive: g]) and two pigment pattern polymorphisms (Burnsi/spotless [B] or spotted [b]; Kandiyohi/mottled [K] or non-mottled[k]) are hypothesized to have adaptive benefits. We assessed spatiotemporal patterns of these polymorphisms during two time periods in one of the largest remaining grasslands in North America. The frequency of the dominant green phenotype remained consistent from the early-to-late 2000s; however, we observed Kandiyohi phenotypes more frequently during 2001–2002 compared to 2009–2010. By contrast, we observed dominant Burnsi phenotypes more frequently in the latter time period. Although not statistically significant, we observed green phenotypes more frequently in areas with less water on the landscape and in locations closer to tree cover. Burnsi phenotypes were more common in wetlands that did not dry out and Kandiyohi phenotypes were more common in wetlands with aquatic vegetation, although not significantly. No pigment polymorphism was associated with body size. We found no indication of spatial structure, suggesting ample gene flow. The correlations were generally weak, but some were consistent with hypotheses of adaptive benefits. This genetically determined phenotypic variation could be important under changing climactic conditions or if land uses change

    Nuttier (A)dS Black Holes in Higher Dimensions

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    We construct new solutions of the vacuum Einstein field equations with cosmological constant. These solutions describe spacetimes with non-trivial topology that are asymptotically dS, AdS or flat. For a negative cosmological constant these solutions are NUT charged generalizations of the topological black hole solutions in higher dimensions. We also point out the existence of such NUT charged spacetimes in odd dimensions and we explicitly construct such spaces in 5 and 7 dimensions. The existence of such spacetimes with non-trivial topology is closely related to the existence of the cosmological constant. Finally, we discuss the global structure of such solutions and possible applications in string theory.Comment: latex, 30 pages, added reference

    GRM7 variants associated with age-related hearing loss based on auditory perception

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    Age-related hearing impairment (ARHI), or presbycusis, is a common condition of the elderly that results in significant communication difficulties in daily life. Clinically, it has been defined as a progressive loss of sensitivity to sound, starting at the high frequencies, inability to understand speech, lengthening of the minimum discernable temporal gap in sounds, and a decrease in the ability to filter out background noise. The causes of presbycusis are likely a combination of environmental and genetic factors. Previous research into the genetics of presbycusis has focused solely on hearing as measured by pure-tone thresholds. A few loci have been identified, based on a best ear pure-tone average phenotype, as having a likely role in susceptibility to this type of hearing loss; and GRM7 is the only gene that has achieved genome-wide significance. We examined the association of GRM7 variants identified from the previous study, which used an European cohort with Z-scores based on pure-tone thresholds, in a European–American population from Rochester, NY (N = 687), and used novel phenotypes of presbycusis. In the present study mixed modeling analyses were used to explore the relationship of GRM7 haplotype and SNP genotypes with various measures of auditory perception. Here we show that GRM7 alleles are associated primarily with peripheral measures of hearing loss, and particularly with speech detection in older adults
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