216 research outputs found

    The Fokker-Planck equation for bistable potential in the optimized expansion

    Full text link
    The optimized expansion is used to formulate a systematic approximation scheme to the probability distribution of a stochastic system. The first order approximation for the one-dimensional system driven by noise in an anharmonic potential is shown to agree well with the exact solution of the Fokker-Planck equation. Even for a bistable system the whole period of evolution to equilibrium is correctly described at various noise intensities.Comment: 12 pages, LATEX, 3 Postscript figures compressed an

    Isolation and preliminary characterization of a caprine rotavirus

    Get PDF
    Five cytopathic rotavirus strains were isolated in MA 104 cells from stool specimens of kids with diarrhoea. Pre-treatment of the virus with trypsin and incorporation of low levels of trypsin in the maintenance medium were important for the successful cultivation of the strains in these cells. The isolates were shown to be group A rotaviruses by antigenic reactivity with a group A monoclonal antibody. This was confirmed by the migration patterns of the viral RNA genome during polyacrylamide gel electrophoresis, which also confirmed that all five strains had an identical RNA electropherotype. Analysis with monoclonal antibodies to the subgroup-specific VP6 antigen showed that these strains carried the subgroup I epitope.The articles have been scanned in colour with a HP Scanjet 5590; 600dpi. Adobe Acrobat XI Pro was used to OCR the text and also for the merging and conversion to the final presentation PDF-format.mn201

    The Kuiper Belt and Other Debris Disks

    Full text link
    We discuss the current knowledge of the Solar system, focusing on bodies in the outer regions, on the information they provide concerning Solar system formation, and on the possible relationships that may exist between our system and the debris disks of other stars. Beyond the domains of the Terrestrial and giant planets, the comets in the Kuiper belt and the Oort cloud preserve some of our most pristine materials. The Kuiper belt, in particular, is a collisional dust source and a scientific bridge to the dusty "debris disks" observed around many nearby main-sequence stars. Study of the Solar system provides a level of detail that we cannot discern in the distant disks while observations of the disks may help to set the Solar system in proper context.Comment: 50 pages, 25 Figures. To appear in conference proceedings book "Astrophysics in the Next Decade

    Use of dispersion modelling for Environmental Impact Assessment of biological air pollution from composting: Progress, problems and prospects

    Get PDF
    © 2017 The Authors With the increase in composting as a sustainable waste management option, biological air pollution (bioaerosols) from composting facilities have become a cause of increasing concern due to their potential health impacts. Estimating community exposure to bioaerosols is problematic due to limitations in current monitoring methods. Atmospheric dispersion modelling can be used to estimate exposure concentrations, however several issues arise from the lack of appropriate bioaerosol data to use as inputs into models, and the complexity of the emission sources at composting facilities. This paper analyses current progress in using dispersion models for bioaerosols, examines the remaining problems and provides recommendations for future prospects in this area. A key finding is the urgent need for guidance for model users to ensure consistent bioaerosol modelling practices

    Using citizen science data to assess the vulnerability of bottlenose dolphins to human impacts along England\u27s South Coast

    Get PDF
    Coastal bottlenose dolphin populations are highly vulnerable due to their small population sizes and proximity to human activities. Long‐term studies in the UK have monitored populations protected within Special Areas of Conservation (SACs) since the 1990s, but a small community of bottlenose dolphins inhabiting the coastal waters of southern England has received much less attention. The English Channel is one of the most heavily impacted marine ecosystems worldwide and increasing anthropogenic pressures pose a severe threat to the long‐term viability of this population. Conservation measures to protect these animals have been hindered by a lack of knowledge of population size, distribution and ranging behaviour. This study aimed to fill these knowledge gaps. A citizen science sighting network yielded 7458 sighting reports of bottlenose dolphins between 2000 and 2020. Resightings of identified individuals were used to estimate abundance, distribution, and ranging behaviour. Social structure analysis revealed a discrete interconnected group of animals in shallow coastal waters, which did not appear to mix with conspecifics identified further offshore. A Bayesian multi‐site mark–recapture analysis estimated that this population comprises around 48 animals (CV = 0.18, 95% HPDI = 38–66). These dolphins ranged between North Cornwall and Sussex, with an average individual range of 530 km (68–760 km). Areas of high‐modelled habitat suitability were found to overlap with high levels of anthropogenic pressure, with pollution and boat traffic identified as the most pervasive threats. Although adult survival rates indicated that the population was relatively stable from 2008 to 2019 (0.945 (0.017 ± SE)), the small population size implies a significant risk to their long‐term viability and resilience to environmental change. By highlighting the most deleterious anthropogenic activities and regions of conservation significance, our results will be useful for developing management policies for threat mitigation and population conservation, to protect this vulnerable group of dolphins

    Magnetic Field Generation in Stars

    Get PDF
    Enormous progress has been made on observing stellar magnetism in stars from the main sequence through to compact objects. Recent data have thrown into sharper relief the vexed question of the origin of stellar magnetic fields, which remains one of the main unanswered questions in astrophysics. In this chapter we review recent work in this area of research. In particular, we look at the fossil field hypothesis which links magnetism in compact stars to magnetism in main sequence and pre-main sequence stars and we consider why its feasibility has now been questioned particularly in the context of highly magnetic white dwarfs. We also review the fossil versus dynamo debate in the context of neutron stars and the roles played by key physical processes such as buoyancy, helicity, and superfluid turbulence,in the generation and stability of neutron star fields. Independent information on the internal magnetic field of neutron stars will come from future gravitational wave detections. Thus we maybe at the dawn of a new era of exciting discoveries in compact star magnetism driven by the opening of a new, non-electromagnetic observational window. We also review recent advances in the theory and computation of magnetohydrodynamic turbulence as it applies to stellar magnetism and dynamo theory. These advances offer insight into the action of stellar dynamos as well as processes whichcontrol the diffusive magnetic flux transport in stars.Comment: 41 pages, 7 figures. Invited review chapter on on magnetic field generation in stars to appear in Space Science Reviews, Springe

    Trans youth, science and art: creating (trans) gendered space

    Get PDF
    This article is based on empirical research which was undertaken as part of the Sci:dentity project funded by the Wellcome Trust. Sci:dentity was a year-long participatory arts project which ran between March 2006 and March 2007. The project offered 18 young transgendered and transsexual people, aged between 14 and 22, an opportunity to come together to explore the science of sex and gender through art. This article focuses on four creative workshops which ran over two months, being the ‘creative engagement’ phase of the project. It offers an analysis of the transgendered space created which was constituted through the logics of recognition, creativity and pedagogy. Following this, the article explores the ways in which these transgendered and transsexual young people navigate gendered practices, and the gendered spaces these practices constitute, in their everyday lives shaped by gendered and sexual normativities. It goes on to consider the significance of trans virtual and physical cultural spaces for the development of trans young peoples' ontological security and their navigations and negotiations of a gendered social world

    Identification of a BRCA2-Specific Modifier Locus at 6p24 Related to Breast Cancer Risk

    Get PDF

    Genome-Wide Association Study in BRCA1 Mutation Carriers Identifies Novel Loci Associated with Breast and Ovarian Cancer Risk

    Get PDF
    BRCA1-associated breast and ovarian cancer risks can be modified by common genetic variants. To identify further cancer risk-modifying loci, we performed a multi-stage GWAS of 11,705 BRCA1 carriers (of whom 5,920 were diagnosed with breast and 1,839 were diagnosed with ovarian cancer), with a further replication in an additional sample of 2,646 BRCA1 carriers. We identified a novel breast cancer risk modifier locus at 1q32 for BRCA1 carriers (rs2290854, P = 2.7×10-8, HR = 1.14, 95% CI: 1.09-1.20). In addition, we identified two novel ovarian cancer risk modifier loci: 17q21.31 (rs17631303, P = 1.4×10-8, HR = 1.27, 95% CI: 1.17-1.38) and 4q32.3 (rs4691139, P = 3.4×10-8, HR = 1.20, 95% CI: 1.17-1.38). The 4q32.3 locus was not associated with ovarian cancer risk in the general population or BRCA2 carriers, suggesting a BRCA1-specific associat
    corecore