618 research outputs found

    The Drell-Yan measurement at COMPASS-II

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    The Drell-Yan process can be used to access Transverse Momentum Dependent Parton Distribution Functions, such as the Boer-Mulders and the Sivers functions, and the transversity function, providing complementary information to what is known from Semi Inclusive Deep Inelastic Scattering data. The COMPASS experiment offers the possibility to study single polarized Drell-Yan processes (π− + p↑ → μ+μ− + X), making use of its large acceptance spectrometer and its unique transversely polarised proton target. A fundamental test of the factorization theorem in the non-perturbative QCD can be performed as well, by verifying the sign change of the Boer-Mulders and the Sivers functions depending if they are accessed via SIDIS or Drell-Yan process. The future Drell-Yan experiment at COMPASS is foreseen in late 2014

    Spin physics in polarised Drell-Yan processes at COMPASS

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    The Drell-Yan process can be used to access Transverse Momentum Dependent Parton Distribution Functions (TMD PDFs), such as Boer-Mulders function, Sivers function and Transversity functions, providing complementary informations to what is known from Semi Inclusive Deep Inelastic Scattering (SIDIS) data. The COMPASS experiment offers the possibility to extract TMD PDFs from Drell-Yan data, using its spectrometer and its unique transversely polarisable target

    The Drell-Yan measurement at COMPASS

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    The Drell-Yan process can be used to access transverse-momentum–dependent parton distribution functions. It provides complementary information to what is known from semi inclusive deep inelastic scattering data. A fundamental test of the factorization theorem in the non-perturbative QCD can be performed as well. The COMPASS experiment offers the possibility to extract TMD PDFs from Drell-Yan data, making use of its large acceptance spectrometer and its unique transversely polarised target. This measurement is described in the COMPASS-II Proposal

    Growth of samarskite crystal under microgravity conditions (M-20)

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    The purpose of the experiment was to grow single crystals of samarskite under microgravity conditions by the traveling solvent float zone (TSFZ) method, and to study the phase relations in the samarskite-related systems involving liquid phases by the slow cooling float zone (SCFZ) method. Samarskite is one of the minerals in a metamict state and is composed of Ca, Fe, Y, U, Th, Nb, Ta, O, etc. Alpha-particles radiating from uranium and/or thorium in the samarskite itself has destroyed its original structure without damaging its chemical composition and its external form. Consequently its structure was converted into a vitreous structure

    Ruddy Shelduck Tadorna ferruginea home range and habitat use during the non-breeding season in Assam, India

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    India is an important non-breeding ground for migratory waterfowl in the Central Asian Flyway. Millions of birds visit wedands across the country, yet information on their distribution, abundance, and use of resources is rudimentary at best. Limited information suggests that populations of several species of migratory ducks are declining due to encroachment of wedand habitats largely by agriculture and industry. The development of conservation strategies is stymied by a lack of ecological information on these species. We conducted a preliminary assessment of the home range and habitat use of Ruddy Shelduck Tadornaferruginea in the northeast Indian state of Assam. Seven Ruddy Shelducks were fitted with solar-powered Global Positioning System (GPS) satellite transmitters, and were tracked on a daily basis during the winter of 2009-2010. Locations from all seven were used to describe habitat use, while locations from four were used to quantify their home range, as the other three had too few locations (<30) for home range estimation. A Brownian Bridge Movement Model (BBMM), used to estimate home ranges, found that the Ruddy Shelduck had an average core use area (i.e. the contour defining 50% of positions) of 40 km 2 (range = 22-87 km2) and an average home range (95% contour) of 610 km2 (range = 222-1,550 km2). Resource Selection Functions (RSF), used to describe habitat use, showed that the birds frequented riverine wetlands more than expected, occurred on grasslands and shrublands in proportion to their availability, and avoided woods and cropland habitats. The core use areas for three individuals (75%) were on the Brahmaputra River, indicating their preference for riverine habitats. Management and protection of riverine habitats and nearby grasslands may benefit conservation efforts for the Ruddy Shelduck and waterfowl species that share these habitats during the non-breeding seaso

    The Aerosphere as a Network Connector of Organisms and Their Diseases

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    Aeroecological processes, especially powered flight of animals, can rapidly connect biological communities across the globe. This can have profound consequences for evolutionary diversification, energy and nutrient transfers, and the spread of infectious diseases. The latter is of particular consequence for human populations, since migratory birds are known to host diseases which have a history of transmission into domestic poultry or even jumping to human hosts. In this chapter, we present a scenario under which a highly pathogenic avian influenza (HPAI) strain enters North America from East Asia via postmolting waterfowl migration. We use an agent-based model (ABM) to simulate the movement and disease transmission among 106 generalized waterfowl agents originating from ten molting locations in eastern Siberia, with the HPAI seeded in only ~102 agents at one of these locations. Our ABM tracked the disease dynamics across a very large grid of sites as well as individual agents, allowing us to examine the spatiotemporal patterns of change in virulence of the HPAI infection as well as waterfowl host susceptibility to the disease. We concurrently simulated a 12-station disease monitoring network in the northwest USA and Canada in order to assess the potential efficacy of these sites to detect and confirm the arrival of HPAI. Our findings indicated that HPAI spread was initially facilitated but eventually subdued by the migration of host agents. Yet, during the 90-day simulation, selective pressures appeared to have distilled the HPAI strain to its most virulent form (i.e., through natural selection), which was counterbalanced by the host susceptibility being conversely reduced (i.e., through genetic predisposition and acquired immunity). The monitoring network demonstrated wide variation in the utility of sites; some were clearly better at providing early warnings of HPAI arrival, while sites further from the disease origin exposed the selective dynamics which slowed the spread of the disease albeit with the result of passing highly virulent strains into southern wintering locales (where human impacts are more likely). Though the ABM presented had generalized waterfowl migration and HPAI disease dynamics, this exercise demonstrates the power of such simulations to examine the extremely large and complex processes which comprise aeroecology. We offer insights into how such models could be further parameterized to represent HPAI transmission risks as well as how ABMs could be applied to other aeroecological questions pertaining to individual-based connectivity

    Morphological changes and vegetation index variation along the western coastal zone of Bangladesh

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    Being a low laying deltaic country, morphological changes along the Bangladesh coastal zones are of major socio-economic and environmental concern. In this study, images of LANDSAT captured during 1989-2010 are analyzed to detect the variation of shoreline positions. Western coast has been divided into different segments and the rates of change of shoreline positions have been analyzed over three time periods 1989-2000, 2000-2006 and 2006-2010. AVHRR GIMMS and MODIS NDVI (Normalized Difference Vegetation Index) data sets are adopted during 1985-2006 and 2005-2010 respectively to monitor the long term variation of NDVI for the segments covered with mangroves. Fourier analysis has been performed to extract primary variation from NDVI time series. River discharge, water- and soil- salinity and wave hind cast (ECMWF) data has been also considered to infer the mechanism of shoreline dynamics and changes of NDVI variations. Every segment underwent rapid erosive changes during the periods of 1989-2000 and 2006-2010, compared to the period of 2000-2006, further segments covered with mangroves changed more rapidly than flat sandy beaches, contradicting the general consensus that mangrove stabilizes the land. Variation of NDVI showed a decreasing trend during the period of 1995-2000 and 2005-2010 at most of the locations, which may an indication of the decreasing tendency of vegetation activity of the area. Oppositely during the periods of 2000-2005, NDVI was in an increasing trend at all locations. Due to the construction of upstream barrage, fresh water discharge through the adjacent rivers decreased and water- and soil- salinity increased around the mangrove forest in the earlier period. This may impact mangrove ecosystem and accelerated the erosion. Shoreline of the western side of every segment faced larger changes compared to east side, which may be due to prevailing waves from south-south-west and consequent sediment transport from west to east

    The Aerosphere as a Network Connector of Organisms and Their Diseases

    Get PDF
    Aeroecological processes, especially powered flight of animals, can rapidly connect biological communities across the globe. This can have profound consequences for evolutionary diversification, energy and nutrient transfers, and the spread of infectious diseases. The latter is of particular consequence for human populations, since migratory birds are known to host diseases which have a history of transmission into domestic poultry or even jumping to human hosts. In this chapter, we present a scenario under which a highly pathogenic avian influenza (HPAI) strain enters North America from East Asia via postmolting waterfowl migration. We use an agent-based model (ABM) to simulate the movement and disease transmission among 106 generalized waterfowl agents originating from ten molting locations in eastern Siberia, with the HPAI seeded in only ~102 agents at one of these locations. Our ABM tracked the disease dynamics across a very large grid of sites as well as individual agents, allowing us to examine the spatiotemporal patterns of change in virulence of the HPAI infection as well as waterfowl host susceptibility to the disease. We concurrently simulated a 12-station disease monitoring network in the northwest USA and Canada in order to assess the potential efficacy of these sites to detect and confirm the arrival of HPAI. Our findings indicated that HPAI spread was initially facilitated but eventually subdued by the migration of host agents. Yet, during the 90-day simulation, selective pressures appeared to have distilled the HPAI strain to its most virulent form (i.e., through natural selection), which was counterbalanced by the host susceptibility being conversely reduced (i.e., through genetic predisposition and acquired immunity). The monitoring network demonstrated wide variation in the utility of sites; some were clearly better at providing early warnings of HPAI arrival, while sites further from the disease origin exposed the selective dynamics which slowed the spread of the disease albeit with the result of passing highly virulent strains into southern wintering locales (where human impacts are more likely). Though the ABM presented had generalized waterfowl migration and HPAI disease dynamics, this exercise demonstrates the power of such simulations to examine the extremely large and complex processes which comprise aeroecology. We offer insights into how such models could be further parameterized to represent HPAI transmission risks as well as how ABMs could be applied to other aeroecological questions pertaining to individual-based connectivity

    A Remote Sensing Approach to Assess the Historical Invasion of \u3cem\u3ePhragmites australis\u3c/em\u3e in a Brackish Coastal Marsh

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    Introduction: Coastal estuarine wetlands provide important habitats for a variety of endemic flora and fauna but are particularly vulnerable to biological invasions. Regular monitoring of changes in these vulnerable wetlands has become increasingly important for effective management, especially considering threats from climate change effects and human disturbance. Historical analyzes of plant invasions may guide targeted management strategies to eradicate harmful species. Estimating the distribution of invasive species has never been more accessible with the improved availability of high-resolution data and innovations in remote sensing, estimating the distribution of invasive species has never been more accessible. Methods: We assessed the spread of non-native Phragmites australis subsp. australis in Suisun Marsh on the upper San Francisco Estuary, one of the largest brackish coastal wetlands in North America. Suisun Marsh consists of managed and tidal wetlands, and efforts have been made to control invasive P. australis on the managed wetlands to support habitat values for wildlife. We used remote-sensing analyzes of publicly available, biennial color-infrared images taken by the National Agriculture Imagery Program (NAIP) to map the expansion of invasive P. australis across two decades. We generated random forest classifications of representative images to map the distribution of P. australis, then calculated a variety of metrics describing the rate and spatial extent of the P. australis spread. Additionally, we ran generalized linear models to examine factors related to the growth of P. australis. Results: Our classifications yielded accuracies of over 90% and showed a 234% (1,084 ha) increase in P. australis between 2003 and 2018. The expansion rate of P. australis patches averaged 1.32 m/year (±0.53 SD) which is higher than most reported in the literature. We found that P. australis expansion in managed areas within levees was significantly correlated with invasion in tidal areas outside the levees on the same parcel and also related to its spread on adjacent parcels. Discussion: Our findings suggest that despite individual landowner management efforts, P. australis has continued to expand substantially throughout Suisun Marsh. Future efforts to treat invasive P. australis may require emphasizing adaptive, collaborative management rather than individual management strategies to ensure the invasive species is eradicated on a large scale to preserve the valued ecosystem functions
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