5,438 research outputs found

    Space acceleration measurement system triaxial sensor head error budget

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    The objective of the Space Acceleration Measurement System (SAMS) is to measure and record the microgravity environment for a given experiment aboard the Space Shuttle. To accomplish this, SAMS uses remote triaxial sensor heads (TSH) that can be mounted directly on or near an experiment. The errors of the TSH are reduced by calibrating it before and after each flight. The associated error budget for the calibration procedure is discussed here

    Majorana bound states in magnetic skyrmions imposed onto a superconductor

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    We consider a superconducting film exchange-coupled to a close-by chiral magnetic layer and study how magnetic skyrmions can induce the formation of Majorana bound states (MBS) in the superconductor. Inspired by a proposal by Yang et al. [Phys. Rev. B 93, 224505 (2016)], which suggested MBS in skyrmions of even winding number, we explore whether such skyrmions could result from a merger of ordinary skyrmions. We conclude that the formation of higher-winding skyrmions is not realistic in chiral magnets. Subsequently, we present a possibility to obtain MBS from realistic skyrmions of winding number one, if a skyrmion-vortex pair is formed instead of a bare skyrmion. Specifically, we show that MBS are supported in a pair of a circular skyrmion and a vortex which both have a winding number of one. We back up our analytical prediction with results from numerical diagonalization and obtain the spatial profile of the MBS. In light of recent experimental progress on the manipulation of skyrmions, such systems are promising candidates to achieve direct spatial control of MBS.Comment: 13 pages, 7 figures. Published versio

    Copyright Revision: Preemption as a Panacea

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    Recurrence rates after EMR of large sessile serrated polyps

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    Background Little is known regarding the recurrence rate after EMR of large (≥20 mm) sessile serrated adenoma/polyps (SSA/Ps). Objective To compare the recurrence rate among SSA/Ps and conventional adenomas in patients referred to a specialty practice for EMR. Design Retrospective cohort study. Setting Academic hospital and a satellite surgery center. Patients A total of 362 consecutive patients referred for resection of large (≥20 mm) polyps in the colorectum. Interventions All EMRs were performed with a submucosal contrast agent. All subjects had a follow-up surveillance examination (inspection and biopsy of the EMR) at our center. Main Outcome Measurements Rates of residual polyp at follow-up examination. Results Residual polyp was identified among 8.7% of SSA/Ps compared with 11.1% for conventional adenomas (P = .8). Limitations Retrospective design, procedures performed by a single experienced endoscopist, low number of serrated lesions. Conclusions The rate of recurrence after EMR of SSA/Ps is similar to the rate after EMR of conventional adenomas

    Cities within cities: Australian and New Zealand art in the 20th century

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    This paper argues for a new conception of both Australian and New Zealand art history based on their long-standing historical connection. The national histories of the art of both countries that dominated the 20th century are revealed as themselves historical, preceded and followed by non-national histories that are in effect part of a wider history of world art. The paper makes its case by looking at a number of artists whose careers cross between the two countries and at the expatriates from both countries who worked together in Europe

    The far-infrared/submillimeter properties of galaxies located behind the Bullet cluster

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    The Herschel Lensing Survey (HLS) takes advantage of gravitational lensing by massive galaxy clusters to sample a population of high-redshift galaxies which are too faint to be detected above the confusion limit of current far-infrared/submillimeter telescopes. Measurements from 100–500 μm bracket the peaks of the far-infrared spectral energy distributions of these galaxies, characterizing their infrared luminosities and star formation rates. We introduce initial results from our science demonstration phase observations, directed toward the Bullet cluster (1E0657-56). By combining our observations with LABOCA 870 μm and AzTEC 1.1 mm data we fully constrain the spectral energy distributions of 19 MIPS 24 μm-selected galaxies which are located behind the cluster. We find that their colors are best fit using templates based on local galaxies with systematically lower infrared luminosities. This suggests that our sources are not like local ultra-luminous infrared galaxies in which vigorous star formation is contained in a compact highly dust-obscured region. Instead, they appear to be scaled up versions of lower luminosity local galaxies with star formation occurring on larger physical scales

    Exact time-dependent density-functional potentials for strongly correlated tunneling electrons

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    By propagating the many-body Schr\"odinger equation, we determine the exact time-dependent Kohn-Sham potential for a system of strongly correlated electrons which undergo field-induced tunneling. Numerous features are entirely absent from the approximations commonly used in time-dependent density-functional theory. The self-interaction correction is strong and time dependent, owing to electron localization, and prominent dynamic spatial potential steps arise from minima in the charge density, as modified by the Coulomb interaction experienced by the partially tunneled electron.Comment: 5 figure

    Coupled KdV equations derived from atmospherical dynamics

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    Some types of coupled Korteweg de-Vries (KdV) equations are derived from an atmospheric dynamical system. In the derivation procedure, an unreasonable yy-average trick (which is usually adopted in literature) is removed. The derived models are classified via Painlev\'e test. Three types of τ\tau-function solutions and multiple soliton solutions of the models are explicitly given by means of the exact solutions of the usual KdV equation. It is also interesting that for a non-Painlev\'e integrable coupled KdV system there may be multiple soliton solutions.Comment: 19 pages, 2 figure
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