12,773 research outputs found

    Density dependent strong coupling constant of QCD derived from compact star data

    Get PDF
    The present work is an endeavour to connect the properties of tiny nearly massless objects with those of some of the most massive ones, the compact stars. Since 1996 there is major influx of X-ray and γ\gamma ray data from binary stars, one or both of which are compact objects that are difficult to explain as neutron stars since they contain a mass M in too small a radius R . The suggestion has been put forward that these are strange quark stars (SS) explainable in a simple model with chiral symmetry restoration (CSR) for the quarks and the M, R and other properties like QPOs (quasi periodic oscillations) in their X-ray power spectrum. It would be nice if this astrophysical data could shed some light on fundamental properties of quarks obeying QCD. One can relate the strong coupling constant of QCD, αs\alpha_s to the quark mass through the Dyson-Schwinger gap equation using the real time formalism of Dolan and Jackiw. This enables us to obtain the density dependence of αs\alpha_s from the simple CSR referred to above. This way fundamental physics, difficult to extract from other models like for example lattice QCD, can be constrained from present-day compact star data and may be put back to modelling the dense quark phase of early universe.Comment: 7 pages, 4 figure

    Cancer complicating systemic lupus erythematosus--a dichotomy emerging from a nested case-control study

    Get PDF
    We determined whether any individual cancers are increased or decreased in a cohort of 595 patients with systemic lupus erythematosus (SLE) followed for up to 32 years at the University College London Hospitals Lupus Clinic, looking for any associated clinical or serological factors and the prognosis after cancer diagnosis

    Managed realignment for habitat compensation: Use of a new intertidal habitat by fishes

    Get PDF
    Managed realignment has become an increasingly common mechanism to increase the efficiency and sustainability of flood defences, reduce defence costs or compensate for habitat losses. This study investigated the use by fishes of a new intertidal habitat, created by managed realignment, intended to compensate for the loss of mudflat associated with a major port development. Although broadly similar, statistically significant differences in fish species composition, abundance, biomass, size structure, diversity and diet composition indicate that the managed realignment is not yet functioning in an identical manner to the mudflat in the adjacent estuary, most likely due to differences in habitat between sites. Notwithstanding, similarity in the species composition of fyke catches in the managed realignment and estuary increased annually during the 5-year study period, suggesting that the mudflat in the realignment is still developing. Indeed, the site will inevitably change over time with accretion, establishment of vegetation and possibly development of creeks. This will not necessarily prevent the aim of the realignment scheme being achieved, as long as sufficient suitable mudflat remains

    Scalability of a packet-switched WDM MAN with support for optical multicasting

    Get PDF
    This paper addresses the scalability (in terms of the number of nodes) of a packetswitched WDM all-optical bi-directional ring for metropolitan area networks. The nodes enable adding/dropping packets to/from all WDM channels on the ring. The nodes are optically transparent to data packets that bypass them. At a linespeed of 2.5 Gbps using directly modulated DFB lasers separated by 400 GHz, EDFAs to compensate for optical power loss and Phasars for wavelength multiplexing/demultiplexing it has been experimentally observed that a single ring can support upto 8 transparent nodes

    Electric fishing survey of the gravel addition sites on the River Wyre, Grizedale Beck and Joshua's Beck.

    Get PDF
    Although geographically the River Wyre lies between two rivers containing major migrations of adult salmon and sea trout, its rod & line fisheries have for a number of years produced exceptionally low catches. In order to determine the causes of this the Wyre Salmon and Sea trout Restoration Group (WSSRG) was conceived in 1994 as a partnership between the then National Rivers Authority (now Environment Agency), local landowners, angling clubs and interested parties. Two studies of 1994 and 1995 stated that there is a shortage of useable spawning gravels on the river. This is compounded by Abbeystead Reservoir acting as a gravel trap, the siltation of gravels on several side becks and problems with access to available gravels by returning adults. There was also perceived to be a need for accurate fishery data from the river encompassing redd counts, catch data and surveys of fry populations. The 1995 report suggested a number of management proposals which might be adopted in order to improve and create available spawning habitat for migratory salmonids. Funding was made available to create three spawning gravels on each of two side becks (Grizedale Beck and Joshua's Beck) and the addition of gravels to a site oh the main river below Abbeystead Reservoir. Modifications were also made to the fish pass at Abbeystead to allow easier passage of fish. These improvements were made in the autumn of 1995. Salmonid spawning redd counting was undertaken on the whole Wyre catchment in 1995/1996 and specific surveys by electric fishing on the gravel enhancement sites in the summer of 1996. This report details the current state of the improvement works that were undertaken and presents the results of electric fishing surveys in September 1996. A number of lessons have been learnt which will be of great benefit to the Fisheries Function in other parts of the Wyre catchment and the Central Area in general
    • …
    corecore