659 research outputs found

    Diseases and parasites of birds: ecology and epidemiology in a changing world

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    Parasites, the diseases they cause, and their hosts together share a complex evolutionary history. In recent years, however, long-term host-parasite-disease associations have been disrupted primarily due to profound anthropogenic changes in the environment and emerging and re-emerging infectious diseases are recognized as important ecological forces. Birds serve as excellent models in the study of the ecology of parasites and diseases. In this study, I evaluated three aspects of avian disease dynamics. First, I reviewed the role of birds in the spread of highly pathogenic avian influenza (HPAI) of the subtype H5N1 from southeastern Asia. Although limited cases of HPAI have been recorded in wild birds, the overwhelming route of movement and geographic spread of the virus has been via poultry trade and related operations, contrary to scientific and media speculation. The role of wild birds in maintaining the disease in the wild remains unknown and requires considerable study. Control of poultry and human-wildlife-domestic animal interfaces needs to be strengthened to prevent the mixing, mutation and spread of such viruses. -- Second, I evaluated the ecology of the Lyme disease spirochete, Borrelia garinii, in seabirds from eastern Canadian colonies. I record the first case of B. garinii from Gull Island, Newfoundland. Movement of this spirochete is consistent with short-distance movements of seabirds and the presence of the seabird tick, Ixodes uriae, the vector of the spirochete. Identical strains occurring on both hemispheres have suggested long distance movement of the spirochete, however, current information does not offer a good explanation for trans-hemispheric exchange. The strains obtained from Gull Island were similar to eastern European strains, consistent with a hypothesized invasion of colonies in the North Sea from mainland Europe followed by a gradual northwestern movement, with seabirds dispersing into Northwest Atlantic seabird colonies. The timing of breeding of the host seabirds and the life cycle of Ixodes uriae are both very important, complex factors influencing the widespread distribution of B. garinii in the northern hemisphere. -- Third, I examined changes in the endoparasite fauna of common (Uria aalge) and Thick-billed Murres (Li. lomvia) since the late sixties in the Northwest Atlantic. Species composition and relative abundance were very different in both species reflecting long-term change in the marine environment. I recorded the first case of Alcataenia longicervica, a tapeworm species endemic to the North Pacific basin, from murres in Newfoundland. The presence of this species in varying abundance in Coats Island, the Gannet Islands, Gull Island and Greenland reflects a possible route of invasion along the Siberian, Kara and Laptev seas with infected intermediate hosts (euphausiids). Changes in distributions of these tapeworms in murres therefore reflect long-term change in the distribution, abundance and intermingling of Arctic, Pacific and Atlantic krill

    Algorithm Certainty Analysis of Spatial Data for Terrain Model

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    The terrain survey techniques of photogrammetry, LIDAR, Sonar or seismic studies are subject to limitation of shadow zones. It is not possible to capture the terrain pattern and requires interpolation and extrapolation for conformal mapping of spatial coordinates for generation of terrain model. The discrete data is mapped through a function set whose domain returns the analytic test in Riemann map. The algorithm adopted in analysis for such mapping does not have a certainty score or probability of degree of correctness conforming to the physical landscape of shadow zones. The aim of the paper is to establish a generator of certainty degree of the mapping along with a continuous terrain model generator. The confirmed mapping of terrain presents a continuous spatial coordinate set which form the boundary of the shadow zone with discrete spatial coordinates. The discrete set is normalized in Gaussian distribution through a Poisson distribution transition. The continuous data set is represented by Laurentian series in which the function will be analytic and can be mapped to Riemann surface with singularities within the annulus and outside the annulus of approximate space sub set (Euclidean space).The singularities will be discarded through Picard's theorem and analytic test at poles with Cauchy's residual theorem is done. The resulting set of spatial coordinates will restructure within Riemann number sphere which will be mapped on the plane as stereographic projection. The Gaussian distribution which forms the basis of analysis will provide with the tool for generating the probability of certainty of every terrain model idealised to conform to the physical landscape

    Artery tertiary lymphoid organs control aorta immunity and protect against atherosclerosis via vascular smooth muscle cell lymphotoxin β receptors

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    Tertiary lymphoid organs (TLOs) emerge during nonresolving peripheral inflammation, but their impact on disease progression remains unknown. We have found in aged Apoe−/− mice that artery TLOs (ATLOs) controlled highly territorialized aorta T cell responses. ATLOs promoted T cell recruitment, primed CD4+ T cells, generated CD4+, CD8+, T regulatory (Treg) effector and central memory cells, converted naive CD4+ T cells into induced Treg cells, and presented antigen by an unusual set of dendritic cells and B cells. Meanwhile, vascular smooth muscle cell lymphotoxin β receptors (VSMC-LTβRs) protected against atherosclerosis by maintaining structure, cellularity, and size of ATLOs though VSMC-LTβRs did not affect secondary lymphoid organs: Atherosclerosis was markedly exacerbated in Apoe−/−Ltbr−/− and to a similar extent in aged Apoe−/−Ltbrfl/flTagln-cre mice. These data support the conclusion that the immune system employs ATLOs to organize aorta T cell homeostasis during aging and that VSMC-LTβRs participate in atherosclerosis protection via ATLOs

    Coexistence and Criticality in Size-Asymmetric Hard-Core Electrolytes

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    Liquid-vapor coexistence curves and critical parameters for hard-core 1:1 electrolyte models with diameter ratios lambda = sigma_{-}/\sigma_{+}=1 to 5.7 have been studied by fine-discretization Monte Carlo methods. Normalizing via the length scale sigma_{+-}=(sigma_{+} + sigma_{-})/2 relevant for the low densities in question, both Tc* (=kB Tc sigma_{+-}/q^2 and rhoc* (= rhoc sigma _{+-}^{3}) decrease rapidly (from ~ 0.05 to 0.03 and 0.08 to 0.04, respectively) as lambda increases. These trends, which unequivocally contradict current theories, are closely mirrored by results for tightly tethered dipolar dimers (with Tc* lower by ~ 0-11% and rhoc* greater by 37-12%).Comment: 4 pages, 5 figure

    Fuzzy logic modelling of snow leopard populations in response to threats from climate change

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    The snow leopard population in Kazakhstan represents a small but important component of the species range, making up around 2.7% of the global range, of which 18,673 km2 lies within protected areas. The most recent population estimate, by Jackson et al. (2008), suggests that there are around 180-200 individuals. Prior to this study there were no reliable estimates of snow leopard numbers in Almaty State Nature Reserve, one of the only two stable populations of snow leopards in Kazakhstan. In total 40 camera traps were deployed for a total of 5152 traps nights and yielded 50 independent capture events of snow leopards (with between 1 and 10 images per event), 275 capture events of primary prey and 68 capture events of secondary prey. The study capture rate of 0.97 independent capture events per 100 trap nights is at the higher end of the range experienced by other studies (see McCarthy et al., 2008) and mark-recapture modelling estimated 11-18 individual snow leopards in the study area which suggests density between 4.4 and 7.2 individuals per 100km2. Our population estimate for the whole reserve is 39.6 individuals, with a standard error of 5.44536 individuals and a 95% confidence interval of 39 to 64. Analysis of movement patterns suggests that individuals frequently crossed valley bottoms and used densely forested habitat in winter, which may indicated prey switching from ibex to forest ungulates. The University of Cumbria has developed a fuzzy logic model which aggregates a wide range of socio-economic and ecological data and provides a tool that can be used to inform the sustainable natural resource and landscape management decision-making process. Our model predicts the consistent negative impact of climate change (warming) at elevations below the tree line; this is particularly significant as the potential positive impacts for snow leopards at high elevation are slower to kick in thereby increasing the habitat squeeze associated with climate change in mountain habitats

    A case of probable esomeprazole-induced transient liver injury in a pregnant woman with hyperemesis.

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    We report a case of 22-year-old primigravida presented to Women's Hospital - Hamad Medical Corporation emergency with severe epigastric pain, nausea, and vomiting. On admission, she was dehydrated with remarkably worsening symptoms. Laboratory findings revealed significantly elevated liver enzymes with unknown etiology. Her past medical history showed an admission for nausea and vomiting 3 weeks previously and she was discharged on antiemetics, and esomeprazole for the first time. Due to the predominantly elevated liver enzymes, the clinical pharmacist discussed the possibility of esomeprazole-induced adverse effects and suggested to suspend esomeprazole based on the evidence from literature review. The liver enzymes showed a substantial improvement within days after the discontinuation of the drug; however, a rechallenge was not done since it could have adversely affected the mother or the fetus. Using the Naranjo Adverse Drug Reaction Probability scales, the adverse reaction due to esomeprazole was classified as 'probably'

    Pyridine clubbed coumarin analogues: Their synthesis and biological studies as antimicrobials and antioxidants

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    1713-1720The major aim of this study is to develop the new class of coumarin candidate clubbed with dihydropyridine-3-carbonitrile with an improved potency as an antimicrobial and antioxidant agent. The key intermediate 6-nitro-4-methyl coumarin-yl chloro acetate 5 have been linked to the 6-(4-fluorophenyl)-2-oxo-4-phenyl-1,2-dihydro pyridine-3-carbonitrile IIa-j derivative to afford 4-methyl-6-nitro-2-oxo-2H-chromen-7-yl-2-(3-cyano-6-(4-fluoro phenyl)-4-(substituted-phenyl) pyridin-2-yl-oxy) acetates 7a-j via efficient organic transformations. All the new derivatives have been characterized by spectral studies (IR, 1H and 13C NMR and mass spectroscopy). In vitro antimicrobial activity have been carried out using the broth microdilution method and antioxidant potency using DPPH bioassays. Bioassay results reveal that compound 7e are equipotent against E. coli with MIC value 50 µg/ mL compared to standard drug ciprofoloxacin. A final analogue 7c with 4-chlorophenyl substituent indicated better antifungal potency against C. albicans with MIC value 100 µg/ mL compared to standard drug griseofulvin. In addition, newly synthesized analogues have been found to be significant scavengers of DPPH radical with IC50 values of 32.11 μg/mL. It has been observed that the potent antibacterial candidate has proved to possess significant antioxidant activity. The presence of chlorine and hydroxy group on phenyl ring plays an important role for the potency in above mentioned biological assay
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