14,815 research outputs found

    Minimising bias in an un-masked, pragmatic rct comparing two treatment pathways for glaucoma by the use of decision support software - the light trial experience

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    ragmatic trials of treatment pathways can require patient awareness of treatment allocation in order to better represent clinical reality, for example when concordance with a treatment has an important effect on outcome. Conversely, masking of treating clinicians to allocation group can be impossible when full clinical assessment requires knowledge of the current treatments, resources do not permit separate teams for treatment and assessment or when such duplication of clinician contact might affect an outcome such as patient experience. The LiGHT trial is a 718 subject multi-centre 6-year NIHR-funded study of two treatment pathways for glaucoma with outcome measures of health related quality of life and cost effectiveness. We aimed to minimise variation in aspects of clinical behaviour that might introduce bias by affecting either of these outcomes

    Spitzer IRAC Photometry for Time Series in Crowded Fields

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    We develop a new photometry algorithm that is optimized for SpitzerSpitzer time series in crowded fields and that is particularly adapted to faint and/or heavily blended targets. We apply this to the 170 targets from the 2015 SpitzerSpitzer microlensing campaign and present the results of three variants of this algorithm in an online catalog. We present detailed accounts of the application of this algorithm to two difficult cases, one very faint and the other very crowded. Several of SpitzerSpitzer's instrumental characteristics that drive the specific features of this algorithm are shared by KeplerKepler and WFIRSTWFIRST, implying that these features may prove to be a useful starting point for algorithms designed for microlensing campaigns by these other missions.Comment: accepted for publication in The Astrophysical Journal Supplement, online catalog available at http://www.astronomy.ohio-state.edu/Spitzer2015

    OGLE-2016-BLG-0613LABb: A Microlensing Planet in a Binary System

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    We present the analysis of OGLE-2016-BLG-0613, for which the lensing light curve appears to be that of a typical binary-lens event with two caustic spikes but with a discontinuous feature on the trough between the spikes. We find that the discontinuous feature was produced by a planetary companion to the binary lens. We find 4 degenerate triple-lens solution classes, each composed of a pair of solutions according to the well-known wide/close planetary degeneracy. One of these solution classes is excluded due to its relatively poor fit. For the remaining three pairs of solutions, the most-likely primary mass is about M10.7MM_1\sim 0.7\,M_\odot while the planet is a super-Jupiter. In all cases the system lies in the Galactic disk, about half-way toward the Galactic bulge. However, in one of these three solution classes, the secondary of the binary system is a low-mass brown dwarf, with relative mass ratios (1 : 0.03 : 0.003), while in the two others the masses of the binary components are comparable. These two possibilities can be distinguished in about 2024 when the measured lens-source relative proper motion will permit separate resolution of the lens and source.Comment: 14 pages, 9 figure

    Spitzer as a microlens parallax satellite : mass and distance measurements of the binary lens system OGLE-2014-BLG-1050L

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    We report the first mass and distance measurements of a caustic-crossing binary system OGLE-2014-BLG-1050 L using the space-based microlens parallax method. Spitzer captured the second caustic crossing of the event, which occurred ~10 days before that seen from Earth. Due to the coincidence that the source-lens relative motion was almost parallel to the direction of the binary-lens axis, the fourfold degeneracy, which was known before only to occur in single-lens events, persists in this case, leading to either a lower-mass (0.2 and 0.07 MΘ) binary at ~1.1 kpc or a higher-mass (0.9 and 0.35 MΘ) binary at ~3.5 kpc. However, the latter solution is strongly preferred for reasons including blending and lensing probability. OGLE-2014-BLG-1050 L demonstrates the power of microlens parallax in probing stellar and substellar binaries.Publisher PDFPeer reviewe

    Limits on light WIMPs from the CDEX-1 experiment with a p-type point-contact germanium detector at the China Jingping Underground Laboratory

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    We report results of a search for light Dark Matter WIMPs with CDEX-1 experiment at the China Jinping Underground Laboratory, based on 53.9 kg-days of data from a p-type point-contact germanium detector enclosed by a NaI(Tl) crystal scintillator as anti-Compton detector. The event rate and spectrum above the analysis threshold of 475 eVee are consistent with the understood background model. Part of the allowed regions for WIMP-nucleus coherent elastic scattering at WIMP mass of 6-20 GeV are probed and excluded. Independent of interaction channels, this result contradicts the interpretation that the anomalous excesses of the CoGeNT experiment are induced by Dark Matter, since identical detector techniques are used in both experiments.Comment: 5 pages, 5 figure

    A Unified Approach to the Classical Statistical Analysis of Small Signals

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    We give a classical confidence belt construction which unifies the treatment of upper confidence limits for null results and two-sided confidence intervals for non-null results. The unified treatment solves a problem (apparently not previously recognized) that the choice of upper limit or two-sided intervals leads to intervals which are not confidence intervals if the choice is based on the data. We apply the construction to two related problems which have recently been a battle-ground between classical and Bayesian statistics: Poisson processes with background, and Gaussian errors with a bounded physical region. In contrast with the usual classical construction for upper limits, our construction avoids unphysical confidence intervals. In contrast with some popular Bayesian intervals, our intervals eliminate conservatism (frequentist coverage greater than the stated confidence) in the Gaussian case and reduce it to a level dictated by discreteness in the Poisson case. We generalize the method in order to apply it to analysis of experiments searching for neutrino oscillations. We show that this technique both gives correct coverage and is powerful, while other classical techniques that have been used by neutrino oscillation search experiments fail one or both of these criteria.Comment: 40 pages, 15 figures. Changes 15-Dec-99 to agree more closely with published version. A few small changes, plus the two substantive changes we made in proof back in 1998: 1) The definition of "sensitivity" in Sec. V(C). It was inconsistent with our actual definition in Sec. VI. 2) "Note added in proof" at end of the Conclusio

    JLab Measurement of the 4^4He Charge Form Factor at Large Momentum Transfers

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    The charge form factor of ^4He has been extracted in the range 29 fm2^{-2} Q277\le Q^2 \le 77 fm2^{-2} from elastic electron scattering, detecting 4^4He nuclei and electrons in coincidence with the High Resolution Spectrometers of the Hall A Facility of Jefferson Lab. The results are in qualitative agreement with realistic meson-nucleon theoretical calculations. The data have uncovered a second diffraction minimum, which was predicted in the Q2Q^2 range of this experiment, and rule out conclusively long-standing predictions of dimensional scaling of high-energy amplitudes using quark counting.Comment: 4 pages, 2 figure

    OGLE-2016-BLG-1469L: Microlensing Binary Composed of Brown Dwarfs

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    We report the discovery of a binary composed of two brown dwarfs, based on the analysis of the microlensing event OGLE-2016-BLG-1469. Thanks to detection of both finite-source and microlens-parallax effects, we are able to measure both the masses M10.05 MM_1\sim 0.05\ M_\odot, M20.01 MM_2\sim 0.01\ M_\odot, and distance DL4.5D_{\rm L} \sim 4.5 kpc, as well as the projected separation a0.33a_\perp \sim 0.33 au. This is the third brown-dwarf binary detected using the microlensing method, demonstrating the usefulness of microlensing in detecting field brown-dwarf binaries with separations less than 1 au.Comment: 8 pages, 8 figure

    Limits on Light Weakly Interacting Massive Particles from the First 102.8 kg ×{\times} day Data of the CDEX-10 Experiment

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    We report the first results of a light weakly interacting massive particles (WIMPs) search from the CDEX-10 experiment with a 10 kg germanium detector array immersed in liquid nitrogen at the China Jinping Underground Laboratory with a physics data size of 102.8 kg day. At an analysis threshold of 160 eVee, improved limits of 8 ×1042\times 10^{-42} and 3 ×1036\times 10^{-36} cm2^{2} at a 90\% confidence level on spin-independent and spin-dependent WIMP-nucleon cross sections, respectively, at a WIMP mass (mχm_{\chi}) of 5 GeV/c2{c}^2 are achieved. The lower reach of mχm_{\chi} is extended to 2 GeV/c2{c}^2.Comment: 5 pages, 4 figure

    Measurement of pretzelosity asymmetry of charged pion production in Semi-Inclusive Deep Inelastic Scattering on a polarized 3^3He target

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    An experiment to measure single-spin asymmetries in semi-inclusive production of charged pions in deep-inelastic scattering on a transversely polarized 3^3He target was performed at Jefferson Lab in the kinematic region of 0.16<x<0.350.16<x<0.35 and 1.4<Q2<2.71.4<Q^2<2.7 GeV2{\rm GeV^2}. The pretzelosity asymmetries on 3^3He, which can be expressed as the convolution of the h1Th^\perp_{1T} transverse momentum dependent distribution functions and the Collins fragmentation functions in the leading order, were measured for the first time. Using the effective polarization approximation, we extracted the corresponding neutron asymmetries from the measured 3^3He asymmetries and cross-section ratios between the proton and 3^3He. Our results show that for both π±\pi^{\pm} on 3^3He and on the neutron the pretzelosity asymmetries are consistent with zero within experimental uncertainties.Comment: 6 pages, 3 figures; enlarged the legends in Fig.3; added 3 citation
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