166 research outputs found

    Habitat and Behavior of the American Woodcock in Northcentral Oklahoma

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    I studied the ecological relationships of a very habitat-specific bird, the American woodcock (Philohela minor, Gmelin), in northcentral Oklahoma, on the southwestern fringe of its range in North America. The primary objective was to evaluate relationships .between woodcock and their habitat by analyzing their breeding behavior, observing their response to habitat manipulation, determining their seasonal numbers and distribution, and by attempting to identify factors responsible for scarcity of woodcock in summer months.Wildlife Ecolog

    CLT for Circular beta-Ensembles at High Temperature

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    We consider the macroscopic large NN limit of the Circular beta-Ensemble at high temperature, and its weighted version as well, in the regime where the inverse temperature scales as ÎČ/N\beta/N for some parameter ÎČ>0\beta>0. More precisely, in the limit N→∞N\to\infty, the equilibrium measure of this particle system is described as the unique minimizer of a functional which interpolates between the relative entropy (ÎČ=0\beta=0) and the weighted logarithmic energy (ÎČ=∞(\beta=\infty). The purpose of this work is to show that the fluctuation of the empirical measure around the equilibrium measure converges towards a Gaussian field whose covariance structure interpolates between the Lebesgue L2L^2 (ÎČ=0\beta=0) and the Sobolev H1/2H^{1/2} (ÎČ=∞ÎČ=\infty) norms. We furthermore obtain a rate of convergence for the fluctuations in the W2W_2 metric. Our proof uses the normal approximation result of Lambert, Ledoux, and Webb [2017], the Coulomb transport inequality of ChafaĂŻ, Hardy, and MaĂŻda [2018], and a spectral analysis for the operator associated with the limiting covariance structure

    CLT for Circular beta-Ensembles at High Temperature

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    We consider the macroscopic large N limit of the Circular beta-Ensemble at high temperature, and its weighted version as well, in the regime where the inverse temperature scales as beta/N for some parameter beta>0. More precisely, in the large N limit, the equilibrium measure of this particle system is described as the unique minimizer of a functional which interpolates between the relative entropy (beta=0) and the weighted logarithmic energy (beta=\infty). More precisely, we provide subGaussian concentration estimates in the W1 metric for the deviations of the empirical measure to this equilibrium mesure. The purpose of this work is to show that the fluctuation of the empirical measure around the equilibrium measure converges towards a Gaussian field whose covariance structure interpolates between the Lebesgue L^2 (beta=0) and the Sobolev H^{1/2} (beta=\infty) norms. We furthermore obtain a rate of convergence for the fluctuations in the W_2 metric. Our proof uses the normal approximation result of Lambert, Ledoux and Webb [2017] the Coulomb transport inequality of Chafai, Hardy, Maida [2018] and a spectral analysis for the operator associated with the limiting covariance structure.Comment: A section added about the continuity of the variance as the inverse temperature beta tends to 0 or infinity. References update

    The impact of aerosols on stratiform clouds over southern West Africa: a large-eddy-simulation study

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    Low-level stratiform clouds (LLSCs) covering a large area appear frequently during the wet monsoon season in southern West Africa. This region is also a place where different types of aerosols coexist, including biomass burning aerosols coming from central and southern Africa and aerosols emitted by local anthropogenic activities. We investigate the indirect and semi-direct effects of these aerosols on the life cycle of LLSCs by conducting a case study based on airborne and ground-based observations from the field campaign of Dynamic-Aerosol-Chemistry-Cloud-Interaction in West Africa (DACCIWA). This case is modeled using a large-eddy-simulation (LES) model with fine resolution and in situ aerosol measurements, including size distribution and chemical composition. The model has successfully reproduced the observed life cycle of the LLSC, from stratus formation to stabilization during the night and to upward development after sunrise until break-up of the cloud deck in the late afternoon. Additional sensitivity simulations using different measured aerosol profiles also suggest that aerosols can affect the cloud life cycle through both the indirect and semi-direct effects. As expected, modeled cloud microphysical features, including cloud droplet number concentration, mean radius, and thus cloud reflectivity, are all controlled by aerosol concentration. However, it is found that the variation in cloud reflectivity induced by different aerosol profiles is not always the only factor in determining the incoming solar radiation at the ground and thus for the cloud life cycle after sunrise. Instead, the difference in cloud fraction brought by dry-air entrainment from above and thus the speed of consequent evaporation – also influenced by aerosol concentration – is another important factor to consider. Clouds influenced by higher aerosol concentrations and thus with a higher number concentration and smaller sizes of cloud droplets are found to evaporate more easily and thus impose a lower cloud fraction. In addition, our sensitivity runs including versus excluding aerosol direct radiative effects have also demonstrated the impacts specifically of solar absorption by black carbon on the cloud life cycle. The semi-direct effect resulting from an excessive atmospheric heating of up to 12 K d−1 by black carbon in our modeled cases is found to lower the cloud top as well as the liquid water path, reducing surface incoming solar radiation and dry entrainment and increasing the cloud fraction.</p

    Sensitivity of arctic surface temperatures to sea ice thickness changes using the regional climate model mar

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    Since the beginning of this century, the Arctic Ocean has experienced a rapid decrease in sea ice extent, which strongly contributes to a pronounced regional climate warming known as “Arctic Amplification”, i.e. two times as large as the global average. Sea ice concentration (SIC) and sea ice thickness (SIT) mainly control changes in Arctic Ocean surface temperatures by insulating the warmer ocean water from the colder air above. Changes in atmospheric temperatures could perturb the Arctic climate, by affecting the regional atmospheric circulation. In most regional climate models (RCMs), SIC is prescribed from climate reanalyses whereas SIT is fixed in space and time, despite observations of large seasonal variations. Here, we compare climate simulations from the regional climate model MAR forced by the ERA-Interim and OSTIA reanalyses, using fixed SIT, to MAR simulations where SIT and SIC are prescribed by the GLORYS2V4 data set. The set of simulations covers the Arctic-CORDEX domain spanning the whole Arctic Ocean at a spatial resolution of 50 km for the period 2000-2015. This study aims to (1) improve the representation of surface temperatures, wind speed and direction within the Arctic boundary layer simulated by MAR, and to (2) estimate the sensitivity of Arctic surface temperatures and atmospheric circulation to prescribed SIT in MAR. Although our findings highlight the local sensitivity of surface temperatures to SIT changes, they also reveal that there is no clear benefit of using space and time varying SIT data sets to force MAR at 50 km resolution.Depuis le dĂ©but de ce siĂšcle, l’OcĂ©an Arctique a connu une diminution rapide de son Ă©tendue de glace de mer, entrainant un rĂ©chauffement climatique rĂ©gional appelĂ© "Amplification Arctique", i.e. deux fois plus marquĂ© que le rĂ©chauffement global. En jouant le rĂŽle d’isolant entre l’ocĂ©an (plus chaud) et l’atmosphĂšre, l’épaisseur et la concentration de glace de mer contrĂŽlent la tempĂ©rature Ă  la surface de l’OcĂ©an Arctique. Une modification de la tempĂ©rature de surface pourrait entrainer une perturbation du systĂšme climatique, par le biais de son influence sur la circulation atmosphĂ©rique rĂ©gionale. Dans la plupart des modĂšles climatiques rĂ©gionaux (RCMs), la concentration de glace de mer est prescrite par des rĂ©analyses, tandis que l’épaisseur de glace de mer est fixe dans le temps et l’espace, malgrĂ© sa variation saisonniĂšre importante. Dans cette Ă©tude, on comparera des simulations du MAR forcĂ© par ERA-intĂ©rim et OSTIA, i.e utilisant une Ă©paisseur de glace de mer fixe, avec des simulations ou l’épaisseur et la concentration de glace de mer sont prescrites par GLORYS2v4. L’ensemble des simulations concerne le domaine CORDEX-Arctique et couvre la pĂ©riode 2000-2015. L’objectif de ce travail est (i) d’amĂ©liorer la reprĂ©sentation de la tempĂ©rature de surface, de la vitesse et direction du vent dans la couche limite atmosphĂ©rique du MAR en Arctique et; (ii) d’estimer la sensibilitĂ© de la tempĂ©rature de surface et de la circulation atmosphĂ©rique Ă  diffĂ©rentes Ă©paisseurs de glace de mer prescrites dans le MAR. Bien que nous dĂ©montrions la sensibilitĂ© locale de la tempĂ©rature de surface Ă  un changement d’épaisseur de glace de mer (fixe), nous montrons aussi qu’il n’y a pas de bĂ©nĂ©fice clair quant Ă  l’utilisation de l’épaisseur de glace de mer variable dans le temps et l’espace comme forçage Ă  la surface du MAR Ă  50 km de rĂ©solution

    Analytic Metaphysics versus Naturalized Metaphysics: The Relevance of Applied Ontology

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    The relevance of analytic metaphysics has come under criticism: Ladyman & Ross, for instance, have suggested do discontinue the field. French & McKenzie have argued in defense of analytic metaphysics that it develops tools that could turn out to be useful for philosophy of physics. In this article, we show first that this heuristic defense of metaphysics can be extended to the scientific field of applied ontology, which uses constructs from analytic metaphysics. Second, we elaborate on a parallel by French & McKenzie between mathematics and metaphysics to show that the whole field of analytic metaphysics, being useful not only for philosophy but also for science, should continue to exist as a largely autonomous field

    Intermittent Lactobacilli-containing Vaginal Probiotic or Metronidazole Use to Prevent Bacterial Vaginosis Recurrence: A Pilot Study Incorporating Microscopy and Sequencing

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    Bacterial vaginosis (BV) is associated with HIV acquisition and adverse pregnancy outcomes. Recurrence after metronidazole treatment is high. HIV-negative, non-pregnant Rwandan BV patients were randomized to four groups (n=17/group) after seven-day oral metronidazole treatment: behavioral counseling only (control), or counseling plus intermittent use of oral metronidazole, Ecologic Femi+ vaginal capsule (containing multiple Lactobacillus and one Bifidobacterium species), or Gynophilus LP vaginal tablet (L. rhamnosus 35) for two months. Vaginal microbiota assessments at all visits included Gram stain Nugent scoring and 16S rRNA gene qPCR and HiSeq sequencing. All interventions were safe. BV (Nugent 7-10) incidence was 10.18 per person-year at risk in the control group, and lower in the metronidazole (1.41/person-year; p=0.004), Ecologic Femi+ (3.58/person-year; p=0.043), and Gynophilus LP groups (5.36/person-year; p=0.220). In mixed effects models adjusted for hormonal contraception/pregnancy, sexual risk-taking, and age, metronidazole and Ecologic Femi+ users, each compared to controls, had higher Lactobacillus and lower BV-anaerobes concentrations and/or relative abundances, and were less likely to have a dysbiotic vaginal microbiota type by sequencing. Inter-individual variability was high and effects disappeared soon after intervention cessation. Lactobacilli-based vaginal probiotics warrant further evaluation because, in contrast to antibiotics, they are not expected to negatively affect microbiota or cause antimicrobial resistance

    Emergence and Modular Evolution of a Novel Motility Machinery in Bacteria

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    Bacteria glide across solid surfaces by mechanisms that have remained largely mysterious despite decades of research. In the deltaproteobacterium Myxococcus xanthus, this locomotion allows the formation stress-resistant fruiting bodies where sporulation takes place. However, despite the large number of genes identified as important for gliding, no specific machinery has been identified so far, hampering in-depth investigations. Based on the premise that components of the gliding machinery must have co-evolved and encode both envelope-spanning proteins and a molecular motor, we re-annotated known gliding motility genes and examined their taxonomic distribution, genomic localization, and phylogeny. We successfully delineated three functionally related genetic clusters, which we proved experimentally carry genes encoding the basal gliding machinery in M. xanthus, using genetic and localization techniques. For the first time, this study identifies structural gliding motility genes in the Myxobacteria and opens new perspectives to study the motility mechanism. Furthermore, phylogenomics provide insight into how this machinery emerged from an ancestral conserved core of genes of unknown function that evolved to gliding by the recruitment of functional modules in Myxococcales. Surprisingly, this motility machinery appears to be highly related to a sporulation system, underscoring unsuspected common mechanisms in these apparently distinct morphogenic phenomena
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