147 research outputs found

    A proposed stratigraphic package for filling a mid-Proterozoic rift basin under the Bellefontaine Outlier area, Ohio, and the consequences of the rift on the formation of the Outlier

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    The discovery of a mid-Proterozoic rift basin in the crystalline basement rocks under the Bellefontaine Outlier area, Ohio has had a number of consequences on our understanding of Precambrian tectonics and stratigraphy of western Ohio and the northcentral North American midcontinent. In this study, a new stratigraphic package has been proposed to fill the ancient rift basin and a geolbgical history of the area from the mid-Proterozoic to the Devonian, has been synthesized to study the consequences of this deep basement feature through time. Three new proposed rift basin-filling volcanic and sedimentary units encode the development, maturation, and termination of the rift. A fourth proposed sedimentary unit, lying above the basin-filling sequence, documents the initial changes of the region to a massive foreland basin in front of newly developed Grenvillian thrust sheets during the late-Proterozoic. The lower contact of the Middle Run Formation has also been extended to a much greater depth overlying the fourth proposed unit and represents welldeveloped foreland basin sediments. Another goal of this study considers tectonic events from the mid-Proterozoic initiation of rifting through the Devonian Acadian Orogeny, to explain the development and incomplete Paleozoic stratigraphy of the Bellefontaine Outlier. Compressive forces associated with the Grenville Orogeny may have propagated the rift-defining fault complexes up through the overlying late-Proterozoic strata and imposed significant structural weaknesses that could be exploited by the compressive forces of the Devonian Acadian Orogeny. During the Acadian, the Outlier block may have been exhumed by the reactivated faults and the Devonian Delaware Limestone and Olentangy Shale units, not present within the Outlier block, may have been syntectonically deposited in flanking basins during the exhumation

    Are residential and nursing homes adequately screening overseas healthcare workers?

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    <p>Abstract</p> <p>Background</p> <p>There has been significant growth in the number of healthcare workers born outside the UK or recruited to the UK from countries with a high prevalence of TB, Hepatitis and other blood borne infections. Government policy recognises the need for occupational health procedures to facilitate treatment for these individuals and to reduce the risk of transmission of disease to patients.</p> <p>The aim of this study was to undertake a survey of nursing and residential homes in South East England, to assess whether homes had occupational health screening policies for healthcare workers who have originated from overseas, and what level of occupational health screening had been undertaken on these employees.</p> <p>Methods</p> <p>An anonymous survey was sent to all 500 homes in West Sussex assessing occupational health practices for "overseas health care workers", defined as health care workers who had been born outside the UK.</p> <p>Results</p> <p>Only one employer (0.8%) reported they had an occupational health screening policy specific for healthcare workers who originate from overseas. Over 80% of homes who had recruited directly had no evidence of screening results for HIV, TB, Hepatitis B and C. The commonest countries of origin for staff were the UK, Philippines, Poland, South Africa, Zimbabwe, and India.</p> <p>Conclusion</p> <p>This study suggests that screening of overseas healthcare workers is not routine practice for residential or nursing care homes and requires further input from Primary Care Trust's, Health Care Commission, Commission for Social Care Inspection, and Professional bodies.</p

    The Galaxy Luminosity Function and Luminosity Density at Redshift z=0.1

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    Using a catalog of 147,986 galaxy redshifts and fluxes from the Sloan Digital Sky Survey (SDSS), we measure the galaxy luminosity density at z = 0.1 in five optical bandpasses corresponding to the SDSS bandpasses shifted to match their rest-frame shape at z = 0.1. We denote the bands (0.1)u, (0.1)g, (0.1)r, (0.1)i, (0.1)z with lambda(eff) = (3216; 4240; 5595; 6792; 8111 Angstrom), respectively. To estimate the luminosity function, we use a maximum likelihood method that allows for a general form for the shape of the luminosity function,fits for simple luminosity and number evolution, incorporates the flux uncertainties, and accounts for the flux limits of the survey. We find luminosity densities at z = 0.1 expressed in absolute AB magnitudes in a Mpc(3) to be (-14.10 +/- 0.15, -15.18 +/- 0.03, - 15.90 +/- 0.03, -16.24 +/- 0.03, -16.56 +/- 0.02) in ((0.1)u, (0.1)g, (0.1)r, (0.1)i, (0.1)z), respectively, for a cosmological model with Omega(0) = 0.3, Omega(Lambda) = 0.7, and h = 1 and using SDSS Petrosian magnitudes. Similar results are obtained using Sersic model magnitudes, suggesting that flux from outside the Petrosian apertures is not a major correction. In the (0.1)r band, the best-fit Schechter function to our results has phi* = (1.49 +/- 0.04) x 10(-2) h(3) Mpc(-3), M-* - 5 log(10) h = - 20.44 +/- 0.01, and alpha = - 1.05 +/- 0.01. In solar luminosities, the luminosity density in (0.1)r is (1.84 +/- 0.04) x 10(8) h L-0.1r,L-. Mpc(-3). Our results in the (0.1)g band are consistent with other estimates of the luminosity density, from the Two-Degree Field Galaxy Redshift Survey and the Millennium Galaxy Catalog. They represent a substantial change ( similar to 0.5 mag) from earlier SDSS luminosity density results based on commissioning data, almost entirely because of the inclusion of evolution in the luminosity function model

    Locally Biased Galaxy Formation and Large Scale Structure

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    We examine the influence of the morphology-density(MD) relation and a wide range of simple models for biased galaxy formation on statistical measures of large scale structure. We contrast the behavior of local biasing models, in which the efficiency of galaxy formation is determined by density, geometry, or velocity dispersion of the local mass distribution, with that of non-local biasing models, in which galaxy formation is modulated coherently over scales larger than the galaxy correlation length. If morphological segregation of galaxies is governed by a local MD relation, then the correlation function of E/S0 galaxies should be steeper and stronger than that of spiral galaxies on small scales, as observed, while on large scales the correlation functions of E/S0 and spiral galaxies should have the same shape but different amplitudes. Similarly, all of our local bias models produce scale-independent amplification of the correlation function and power spectrum in the linear and mildly non-linear regimes; only a non-local biasing mechanism can alter the shape of the power spectrum on large scales. Moments of the biased galaxy distribution retain the hierarchical pattern of the mass moments, but biasing alters the values and scale-dependence of the hierarchical amplitudes S3 and S4. Pair-weighted moments of the galaxy velocity distribution are sensitive to the details of the biasing prescription. The non-linearity of the relation between galaxy density and mass density depends on the biasing prescription and the smoothing scale, and the scatter in this relation is a useful diagnostic of the physical parameters that determine the bias. Although the sensitivity of galaxy clustering statistics to the details of biasing is an obstacle to testing cosmological models, it is an asset for testing galaxy formation theories.Comment: 47 pages including 17 Figures, submitted to Ap

    Spectroscopic Target Selection in the Sloan Digital Sky Survey: The Quasar Sample

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    We describe the algorithm for selecting quasar candidates for optical spectroscopy in the Sloan Digital Sky Survey. Quasar candidates are selected via their non-stellar colors in "ugriz" broad-band photometry, and by matching unresolved sources to the FIRST radio catalogs. The automated algorithm is sensitive to quasars at all redshifts lower than z=5.8. Extended sources are also targeted as low-redshift quasar candidates in order to investigate the evolution of Active Galactic Nuclei (AGN) at the faint end of the luminosity function. Nearly 95% of previously known quasars are recovered (based on 1540 quasars in 446 square degrees). The overall completeness, estimated from simulated quasars, is expected to be over 90%, whereas the overall efficiency (quasars:quasar candidates) is better than 65%. The selection algorithm targets ultraviolet excess quasars to i^*=19.1 and higher-redshift (z>3) quasars to i^*=20.2, yielding approximately 18 candidates per square degree. In addition to selecting ``normal'' quasars, the design of the algorithm makes it sensitive to atypical AGN such as Broad Absorption Line quasars and heavily reddened quasars.Comment: 62 pages, 15 figures (8 color), 8 tables. Accepted by AJ. For a version with higher quality color figures, see http://archive.stsci.edu/sdss/quasartarget/RichardsGT_qsotarget.preprint.p

    KL Estimation of the Power Spectrum Parameters from the Angular Distribution of Galaxies in Early SDSS Data

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    We present measurements of parameters of the 3-dimensional power spectrum of galaxy clustering from 222 square degrees of early imaging data in the Sloan Digital Sky Survey. The projected galaxy distribution on the sky is expanded over a set of Karhunen-Loeve eigenfunctions, which optimize the signal-to-noise ratio in our analysis. A maximum likelihood analysis is used to estimate parameters that set the shape and amplitude of the 3-dimensional power spectrum. Our best estimates are Gamma=0.188 +/- 0.04 and sigma_8L = 0.915 +/- 0.06 (statistical errors only), for a flat Universe with a cosmological constant. We demonstrate that our measurements contain signal from scales at or beyond the peak of the 3D power spectrum. We discuss how the results scale with systematic uncertainties, like the radial selection function. We find that the central values satisfy the analytically estimated scaling relation. We have also explored the effects of evolutionary corrections, various truncations of the KL basis, seeing, sample size and limiting magnitude. We find that the impact of most of these uncertainties stay within the 2-sigma uncertainties of our fiducial result.Comment: Fig 1 postscript problem correcte

    The Angular Correlation Function of Galaxies from Early SDSS Data

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    The Sloan Digital Sky Survey is one of the first multicolor photometric and spectroscopic surveys designed to measure the statistical properties of galaxies within the local Universe. In this Letter we present some of the initial results on the angular 2-point correlation function measured from the early SDSS galaxy data. The form of the correlation function, over the magnitude interval 18<r*<22, is shown to be consistent with results from existing wide-field, photographic-based surveys and narrower CCD galaxy surveys. On scales between 1 arcminute and 1 degree the correlation function is well described by a power-law with an exponent of ~ -0.7. The amplitude of the correlation function, within this angular interval, decreases with fainter magnitudes in good agreement with analyses from existing galaxy surveys. There is a characteristic break in the correlation function on scales of approximately 1-2 degrees. On small scales, < 1', the SDSS correlation function does not appear to be consistent with the power-law form fitted to the 1'< theta <0.5 deg data. With a data set that is less than 2% of the full SDSS survey area, we have obtained high precision measurements of the power-law angular correlation function on angular scales 1' < theta < 1 deg, which are robust to systematic uncertainties. Because of the limited area and the highly correlated nature of the error covariance matrix, these initial results do not yet provide a definitive characterization of departures from the power-law form at smaller and larger angles. In the near future, however, the area of the SDSS imaging survey will be sufficient to allow detailed analysis of the small and large scale regimes, measurements of higher-order correlations, and studies of angular clustering as a function of redshift and galaxy type

    Family planning, antenatal and delivery care: cross-sectional survey evidence on levels of coverage and inequalities by public and private sector in 57 low- and middle-income countries.

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    OBJECTIVE: The objective of this study was to assess the role of the private sector in low- and middle-income countries (LMICs). We used Demographic and Health Surveys for 57 countries (2000-2013) to evaluate the private sector's share in providing three reproductive and maternal/newborn health services (family planning, antenatal and delivery care), in total and by socio-economic position. METHODS: We used data from 865 547 women aged 15-49, representing a total of 3 billion people. We defined 'met and unmet need for services' and 'use of appropriate service types' clearly and developed explicit classifications of source and sector of provision. RESULTS: Across the four regions (sub-Saharan Africa, Middle East/Europe, Asia and Latin America), unmet need ranged from 28% to 61% for family planning, 8% to 22% for ANC and 21% to 51% for delivery care. The private-sector share among users of family planning services was 37-39% across regions (overall mean: 37%; median across countries: 41%). The private-sector market share among users of ANC was 13-61% across regions (overall mean: 44%; median across countries: 15%). The private-sector share among appropriate deliveries was 9-56% across regions (overall mean: 40%; median across countries: 14%). For all three healthcare services, women in the richest wealth quintile used private services more than the poorest. Wealth gaps in met need for services were smallest for family planning and largest for delivery care. CONCLUSIONS: The private sector serves substantial numbers of women in LMICs, particularly the richest. To achieve universal health coverage, including adequate quality care, it is imperative to understand this sector, starting with improved data collection on healthcare provision
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