10,038 research outputs found

    Two-Black-Hole Bound States

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    The quantum mechanics of NN slowly-moving BPS black holes in five dimensions is considered. A divergent continuum of states describing arbitrarily closely bound black holes with arbitrarily small excitation energies is found. A superconformal structure appears at low energies and can be used to define an index counting the weighted number of supersymmetric bound states. It is shown that the index is determined from the dimensions of certain cohomology classes on the symmetric product of NN copies of R4R^4. An explicit computation for the case of N=2 with no angular momentum yields a finite nonzero result.Comment: 21 pages, harvmac. Minor corrections to section

    CMB Signatures of a Primordial Magnetic Field

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    A primordial stochastic magnetic field will induce temperature and polarization fluctuations in the cosmic microwave background. We outline a calculation of the resulting fluctuation power spectra and present numerical results.Comment: To appear in "Cosmology and Particle Physics" eds J. Garcia-Bellido, R. Durrer, and M. Shaposhnikov, 6 pages, 1 figure, LaTeX uses aipproc.sty (included

    Spinning Bound States of Two and Three Black Holes

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    Bound states of BPS particles in five-dimensional N=2 supergravity are counted by a topological index. We compute this bound state index exactly for two and three black holes as a function of the SU(2)_L angular momentum. The required regulator for the infrared continuum of near-coincident black holes is chosen in accord with the enhanced superconformal symmetry.Comment: 22 pages, Harvma

    Patterns of population location in Auckland

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    This paper uses spatial statistical techniques to examine the economic determinants of residential location patterns in Auckland in 2006. The primary empirical focus of this paper is descriptive. We seek to establish the extent to which there are identifiable population subgroups that cluster together within the Auckland Urban Area, and further, to ascertain where these groups mainly live. It confirms previous findings of strong ethnic clustering and identifies clustering by qualification, income, and country of birth. It examines the interaction between incomes, land prices, and population density, and the relationship of land price with access to selected locational amenities.Residential location choice; local amenities; residential sorting

    Global Innovations in Measurement and Evaluation

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    We researched the latest developments in theory and practice in measurement and evaluation. And we found that new thinking, techniques, and technology are influencing and improving practice. This report highlights 8 developments that we think have the greatest potential to improve evaluation and programme design, and the careful collection and use of data. In it, we seek to inform and inspire—to celebrate what is possible, and encourage wider application of these ideas

    Mass mortalities in bivalve populations: A review of the edible cockle Cerastoderma edule (L.)

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    Mass mortalities in bivalve populations have long been of particular concern, especially when the species supports a commercial fishery or is of conservation interest. Here we consider the evidence of mass mortalities of the edible cockle, Cerastoderma edule (L.). Through the construction of a conceptual model eight potential factors (or groups of factors) which may cause mass mortalities are identified and reviewed. These include: food limitation; density; oxygen depletion and organic loadings; temperature and salinity; parasites, pathogens and commensals; toxicants and other persistent pollutants; predation, and changes in sediment, suspended solids, topography and bathymetry. The interplay between factors in recognized and discussed based on evidence mainly from the published literature relating to temperate edible cockle beds. Anecdotal evidence is also reported from a structured survey of site-specific evidence provided by fisheries managers in England and Wales. Case studies from the UK and Europe indicate that there is often no single, clear generic cause of mass mortalities in cockle populations. The importance of linked site-specific scientific investigations and laboratory-based experiments to fill the gaps in our current understanding of mass mortalities in bivalve species is highlighted as necessary to take account of both local extrinsic and intrinsic factors

    Residential sorting across Auckland neighbourhoods

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    This paper addresses the extent to which people in Auckland exhibit residential location patterns that differ between groups, i.e. the extent to which they are spatially sorted. To measure patterns of residential location, the paper uses the index of segregation, an isolation index, Gini coefficients, Ellison & Glaeser and Maurel & Sédillot concentration measures, Moran’s I and Getis and Ord’s G*. Results are presented based on a classification of the population in different ways: ethnicity, income, education, age and country of birth. Both city-wide and local measures are considered. We find that ethnic-based sorting is the strongest indicator of residential sorting patterns, but soring by income, education and age is also present. Sorting by income and qualifications is strongest at the top and, to lesser extent, at the bottom of the income and qualifications range. Age segregation is most pronounced for older residents. Clustering is strongest within a range of up to one kilometre and declines significantly over greater distances. Local analysis by means of Getis and Ord’s G* calculations suggest significant ethnic clustering. Apart from Maori and Pacific Islanders, ethnic groups tend to locate way from each other, as confirmed with cross-Moran’s I calculations. When considering interactions between ethnicity and income we find that the location of ethnicity income subgroups is more strongly related to neighbourhood income

    Validating a novel web-based method to capture disease progression outcomes in multiple sclerosis

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    The Expanded Disability Status Scale (EDSS) is the current ‘gold standard’ for monitoring disease severity in multiple sclerosis (MS). The EDSS is a physician-based assessment. A patient-related surrogate for the EDSS may be useful in remotely capturing information. Eighty-one patients (EDSS range 0–8) having EDSS as part of clinical trials were recruited. All patients carried out the web-based survey with minimal assistance. Full EDSS scores were available for 78 patients. The EDSS scores were compared to those generated by the online survey using analysis of variance, matched pair test, Pearson’s coefficient, weighted kappa coefficient, and the intra-class correlation coefficient. The internet-based EDSS scores showed good correlation with the physician-measured assessment (Pearson’s coefficient = 0.85). Weighted kappa for full agreement was 0.647. Full agreement was observed in 20 patient
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