2,491 research outputs found

    The Palaeo-ecology and Biostratigraphy of the foraminifera from the Oxfordian of north Dorset

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    The Oxfordian rocks of north Dorset are poorly exposed at outcrop. A drilling operation was devised and implemented and the complete sequence of strata from the Weymouth Member of the Oxford Clay Formation through to the Ringstead Waxy Clay Formation was penetrated. Three boreholes were drilled; the Hallett's Farm Borehole, covering the strata from the stratigraphically youngest Ringstead Waxy Clay Formation down to the Cucklington Oolite; the Bowden Farm Borehole, continuing the sequence from the Cucklington Oolite into the lower part of the Hazelbury Bryan Formation and the Hartmoor Hill Borehole which continues downward into the Oxford Clay Formation. A continuous succession of the Corallian rocks from north Dorset was obtained. The fresh borehole material was examined for microfossils, with further samples coming from the BGS East Stour Borehole. A diverse assemblage was extracted. The foraminiferal assemblage was examined and includes representatives of 26 families, comprising 26 genera and 148 species. All species were identified and the taxonomy of each studied and described or confirmed. The assemblage is more diverse than previously recorded Corallian assemblages, partly due to the freshness of the borehole material which is not affected by the weathering processes present at surface outcrops. The regional lithostratigraphy defined by the British Geological Survey (Bristow et al, 1995) is confirmed and lithological boundaries not visible at outcrop are described. The distribution and abundance patterns of foraminiferal taxa are analysed and various statistical indices are compared for each borehole. Multivariate methods are employed and in particular non-metric Multidimensional Scaling is used in an attempt to divide the samples into groups which are palaeo-environmentally significant. The authenticity of this method is checked against a Hierarchical Agglomerative Clustering technique. The sample groups are used to define biofacies, fifteen of which are recognised within the studied interval. The correlation of the four boreholes is achieved using lithological techniques, ammonite zonation, foraminiferal biohorizons and the biofacies defined by multivariate analysis. A total of 21 biohorizons are identified with certain horizons coinciding with lithological boundaries and previously defined unconformities recognised within the Oxfordian of Dorset. The long ranging nature of the majority of Upper Jurassic foraminifera precludes the definition of a rigorous biostratigraphic zonation. The important biostratigraphic species for the Upper Jurassic are recorded however, and a tentative zonation, based on the concept of interval zones (Salvador, 1995) is proposed. Eleven zones are recognised.British Geological Survey, Exete

    Optimal Survey Strategies and Predicted Planet Yields for the Korean Microlensing Telescope Network

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    The Korean Microlensing Telescope Network (KMTNet) will consist of three 1.6m telescopes each with a 4 deg^{2} field of view (FoV) and will be dedicated to monitoring the Galactic Bulge to detect exoplanets via gravitational microlensing. KMTNet's combination of aperture size, FoV, cadence, and longitudinal coverage will provide a unique opportunity to probe exoplanet demographics in an unbiased way. Here we present simulations that optimize the observing strategy for, and predict the planetary yields of, KMTNet. We find preferences for four target fields located in the central Bulge and an exposure time of t_{exp} = 120s, leading to the detection of ~2,200 microlensing events per year. We estimate the planet detection rates for planets with mass and separation across the ranges 0.1 <= M_{p}/M_{Earth} <= 1000 and 0.4 <= a/AU <= 16, respectively. Normalizing these rates to the cool-planet mass function of Cassan (2012), we predict KMTNet will be approximately uniformly sensitive to planets with mass 5 <= M_{p}/M_{Earth} <= 1000 and will detect ~20 planets per year per dex in mass across that range. For lower-mass planets with mass 0.1 <= M_{p}/M_{Earth} < 5, we predict KMTNet will detect ~10 planets per year. We also compute the yields KMTNet will obtain for free-floating planets (FFPs) and predict KMTNet will detect ~1 Earth-mass FFP per year, assuming an underlying population of one such planet per star in the Galaxy. Lastly, we investigate the dependence of these detection rates on the number of observatories, the photometric precision limit, and optimistic assumptions regarding seeing, throughput, and flux measurement uncertainties.Comment: 29 pages, 31 figures, submitted to ApJ. For a brief video explaining the key results of this paper, please visit: https://www.youtube.com/watch?v=e5rWVjiO26

    BLOOD FLOW RESTRICTION DOES NOT AFFECT ACUTE MEASURES OF POWER AND FATIGUE DURING MAXIMAL CYCLING AMONG WOMEN

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    While it is known that blood flow restriction (BFR) can positively affect training and rehabilitation progression timelines, the physiological basis of this intervention is not fully understood. The purpose of this study was to determine the short-term impact of BFR upon power and fatigue performance measures during maximal cycling. In this study, maximal cycling was assessed using the Wingate Anaerobic Test (WAnT). Using a counterbalanced design, fourteen female participants completed standardized BFR and non-BFR protocols while completing the WAnT. No statistically-significant differences (p ≀ 0.05) were found between conditions for measures of peak power (PP), low power (LP) or fatigue index (FI). These findings suggest that BFR had no statistically-significant acute effect on these performance measures commonly assessed during the WAnT

    THE EFFECTS OF BLOOD FLOW RESTRICTION ON MEASURES OF GROSS MOTOR COORDINATION DURING THE WINGATE ANAEROBIC TEST

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    To date little research has addressed the impact of blood flow restriction (BFR) training upon gross motor coordination measures (GMCM) during a wide variety of maximal activities. The purpose of this study was to assess the effects of BFR on GMCM exhibited during maximal cycling. The performance of 14 females between the ages of eighteen and thirty-five were analyzed during the Wingate Anaerobic Test (WAnT). The participants completed the test under two conditions, using BFR and without. Results showed statistically significant differences (p ≀ 0.05) between conditions for dependent variables assessed throughout this common 30 second test of maximal cycling. These findings suggest that BFR negatively influenced GMCM exhibited during the WAnT

    Planet Sensitivity from Combined Ground- and Space-based Microlensing Observations

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    To move one step forward toward a Galactic distribution of planets, we present the first planet sensitivity analysis for microlensing events with simultaneous observations from space and the ground. We present this analysis for two such events, OGLE-2014-BLG-0939 and OGLE-2014-BLG-0124, which both show substantial planet sensitivity even though neither of them reached high magnification. This suggests that an ensemble of low to moderate magnification events can also yield significant planet sensitivity and therefore probability to detect planets. The implications of our results to the ongoing and future space-based microlensing experiments to measure the Galactic distribution of planets are discussed.Comment: 10 pages, 5 figures, 1 table; ApJ in pres

    Effect of Gene Therapy on Visual Function in Leber's Congenital Amaurosis

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    Early-onset, severe retinal dystrophy caused by mutations in the gene encoding retinal pigment epithelium–specific 65-kD protein (RPE65) is associated with poor vision at birth and complete loss of vision in early adulthood. We administered to three young adult patients subretinal injections of recombinant adeno-associated virus vector 2/2 expressing RPE65 complementary DNA (cDNA) under the control of a human RPE65 promoter. There were no serious adverse events. There was no clinically significant change in visual acuity or in peripheral visual fields on Goldmann perimetry in any of the three patients. We detected no change in retinal responses on electroretinography. One patient had significant improvement in visual function on microperimetry and on dark-adapted perimetry. This patient also showed improvement in a subjective test of visual mobility. These findings provide support for further clinical studies of this experimental approach in other patients with mutant RPE65. (ClinicalTrials.gov number, NCT00643747.)Supported by grants from the U.K. Department of Health, the British Retinitis Pigmentosa Society, and the Special Trustees of Moorfields Eye Hospital, and by the Sir Jules Thorn Charitable Trust, the Wellcome Trust, the European Union (EVI-Genoret and Clinigene programs), the Medical Research Council, Foundation Fighting Blindness, Fight for Sight, the Ulverscroft Foundation, Fighting Blindness (Ireland), Moorfields Eye Hospital, and Institute of Ophthalmology Biomedical Research Centre for Ophthalmology, University College London

    OGLE-2018-BLG-0022: First Prediction of an Astrometric Microlensing Signal from a Photometric Microlensing Event

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    In this work, we present the analysis of the binary microlensing event OGLE-2018-BLG-0022 that is detected toward the Galactic bulge field. The dense and continuous coverage with the high-quality photometry data from ground-based observations combined with the space-based {\it Spitzer} observations of this long time-scale event enables us to uniquely determine the masses M1=0.40±0.05 M⊙M_1=0.40 \pm 0.05~M_\odot and M2=0.13±0.01 M⊙M_2=0.13\pm 0.01~M_\odot of the individual lens components. Because the lens-source relative parallax and the vector lens-source relative proper motion are unambiguously determined, we can likewise unambiguously predict the astrometric offset between the light centroid of the magnified images (as observed by the {\it Gaia} satellite) and the true position of the source. This prediction can be tested when the individual-epoch {\it Gaia} astrometric measurements are released.Comment: 10 pages, 10 figures, 4 table

    SpitzerSpitzer Parallax of OGLE-2018-BLG-0596: A Low-mass-ratio Planet around an M-dwarf

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    We report the discovery of a SpitzerSpitzer microlensing planet OGLE-2018-BLG-0596Lb, with preferred planet-host mass ratio q∌2×10−4q \sim 2\times10^{-4}. The planetary signal, which is characterized by a short (∌1 day)(\sim 1~{\rm day}) "bump" on the rising side of the lensing light curve, was densely covered by ground-based surveys. We find that the signal can be explained by a bright source that fully envelops the planetary caustic, i.e., a "Hollywood" geometry. Combined with the source proper motion measured from GaiaGaia, the SpitzerSpitzer satellite parallax measurement makes it possible to precisely constrain the lens physical parameters. The preferred solution, in which the planet perturbs the minor image due to lensing by the host, yields a Uranus-mass planet with a mass of Mp=13.9±1.6 M⊕M_{\rm p} = 13.9\pm1.6~M_{\oplus} orbiting a mid M-dwarf with a mass of Mh=0.23±0.03 M⊙M_{\rm h} = 0.23\pm0.03~M_{\odot}. There is also a second possible solution that is substantially disfavored but cannot be ruled out, for which the planet perturbs the major image. The latter solution yields Mp=1.2±0.2 M⊕M_{\rm p} = 1.2\pm0.2~M_{\oplus} and Mh=0.15±0.02 M⊙M_{\rm h} = 0.15\pm0.02~M_{\odot}. By combining the microlensing and GaiaGaia data together with a Galactic model, we find in either case that the lens lies on the near side of the Galactic bulge at a distance DL∌6±1 kpcD_{\rm L} \sim 6\pm1~{\rm kpc}. Future adaptive optics observations may decisively resolve the major image/minor image degeneracy.Comment: 34 pages, 8 figures, Submitted to AAS journa
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