77 research outputs found

    Residual Impact of Previous Injury on Musculoskeletal Characteristics in Special Forces Operators

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    Background: Musculoskeletal injuries are a significant burden to United States Army Special Operations Forces. The advanced tactical skill level and physical training required of Army Special Operators highlights the need to optimize musculoskeletal characteristics to reduce the likelihood of suffering a recurrent injury. Purpose: To identify the residual impact of previous injury on musculoskeletal characteristics. Study Design: Cross-sectional study; Level of evidence, 3. Methods: Isokinetic strength of the knee, shoulder, and back and flexibility of the shoulder and hamstrings were assessed as part of a comprehensive human performance protocol, and self-reported musculoskeletal injury history was obtained. Subjects were stratified based on previous history of low back, knee, or shoulder injury, and within-group and between-group comparisons were made for musculoskeletal variables. Results: Knee injury analysis showed no significant strength or flexibility differences. Shoulder injury analysis found internal rotation strength of the healthy subjects (H) was significantly higher compared with injured (I) and uninjured (U) limbs of the injured group (H, 60.8 ± 11.5 percent body weight [%BW]; I, 54.5 ± 10.5 %BW; U, 55.5 ± 11.3 %BW) (P = .014 [H vs I] and P = .05 [H vs U]). The external rotation/internal rotation strength ratio was significantly lower in the healthy subjects compared with injured and uninjured limbs of the injured group (H, 0.653 ± 0.122; I, 0.724 ± 0.121; U, 0.724 ± 0.124) (P = .026 [H vs I] and P = .018 [H vs U]). Posterior shoulder tightness was significantly different between the injured and uninjured limb of the injured group (I, 111.6° ± 9.4°; U, 114.4° ± 9.3°; P = .008). The back injury analysis found no significant strength differences between the healthy and injured groups. Conclusion: Few physical differences existed between operators with prior knee or back injury. However, operators with a previous history of shoulder injury demonstrated significantly less shoulder strength than uninjured operators as well as decreased shoulder flexibility on the injured side. All operators, regardless of prior injury, must perform the same tasks; therefore, a targeted injury rehabilitation/human performance training specifically focused on internal rotation strength and tightness of the posterior capsule may help reduce the risk for recurrence of injury. Operators presenting with musculoskeletal asymmetries and/or insufficient strength ratios may be predisposed to musculoskeletal injury. Clinical Relevance: Specific fitness programs to compensate for deficiencies in strength and flexibility need to be designed that may reduce the risk of injuries in Special Forces Operators

    Psi prime to J/psi Ratio Measurements in PHENIX at RHIC

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    The ratio of the ψ\psi' over the J/ψJ/\psi production cross section in the dielectron channel has been measured in s=\sqrt{s}= 200 GeV p+pp+p collisions with the PHENIX detector at RHIC. The analysis is based on fitting of the dielectron invariant mass spectra in the area around the J/ψJ/\psi and ψ\psi' signals in order to extract a ratio ψ\psi' over J/ψJ/\psi of 0.019±0.005(\pm 0.005(stat)±0.002()\pm 0.002(sys)) and a fractional feed-down contribution to J/ψJ/\psi from ψ\psi^\prime of 8.6±2.58.6 \pm 2.5 %.Comment: 4 pages, 7 figures submitted to: Indian Journal of Physics (2010) - Proceedings of the 20th International Conference on Ultra-Relativistic Nucleus-Nucleus Collisions (QM2008

    Long term photometric monitoring with the Mercator telescope. Frequencies and mode identification of variable O-B stars

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    Aims. We selected a large sample of O-B stars that were considered as (candidate) slowly pulsating B, beta Cep, and Maia stars after the analysis of their hipparcos data. We analysed our new seven passband geneva data collected for these stars during the first three years of scientific operations of the mercator telescope. We performed a frequency analysis for 28 targets with more than 50 high-quality measurements to improve their variability classification. For the pulsating stars, we tried both to identify the modes and to search for rotationally split modes. Methods: We searched for frequencies in all the geneva passbands and colours by using two independent frequency analysis methods and we applied a 3.6 S/N-level criterion to locate the significant peaks in the periodograms. The modes were identified by applying the method of photometric amplitudes for which we calculated a large, homogeneous grid of equilibrium models to perform a pulsational stability analysis. When both the radius and the projected rotational velocity of an object are known, we determined a lower limit for the rotation frequency to estimate the expected frequency spacings in rotationally split pulsation modes. Results: We detected 61 frequencies, among which 33 are new. We classified 21 objects as pulsating variables (7 new confirmed pulsating stars, including 2 hybrid beta Cep/SPB stars), 6 as non-pulsating variables (binaries or spotted stars), and 1 as photometrically constant. All the Maia candidates were reclassified into other variability classes. We performed mode identification for the pulsating variables for the first time. The most probable l value is 0, 1, 2, and 4 for 1, 31, 9, and 5 modes, respectively, including only 4 unambiguous identifications. For 7 stars we cannot rule out that some of the observed frequencies belong to the same rotationally split mode. For 4 targets we may begin to resolve close frequency multiplets. Based on observations collected with the p7 photometer attached to the Flemish 1.2-m mercator telescope situated at the Roque de los Muchachos observatory on La Palma (Spain). Section [see full textsee full text], including Figs. is only available in electronic form at http://www.aanda.org, and Tables 2 and 3 are only available in electronic form at the CDS via anonymous ftp to cdsarc.u-strasbg.fr (130.79.128.5) or via http://cdsweb.u-strasbg.fr/cgi-bin/qcat?J/A+A/463/243Peer reviewe

    The Evolution of Compact Binary Star Systems

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    We review the formation and evolution of compact binary stars consisting of white dwarfs (WDs), neutron stars (NSs), and black holes (BHs). Binary NSs and BHs are thought to be the primary astrophysical sources of gravitational waves (GWs) within the frequency band of ground-based detectors, while compact binaries of WDs are important sources of GWs at lower frequencies to be covered by space interferometers (LISA). Major uncertainties in the current understanding of properties of NSs and BHs most relevant to the GW studies are discussed, including the treatment of the natal kicks which compact stellar remnants acquire during the core collapse of massive stars and the common envelope phase of binary evolution. We discuss the coalescence rates of binary NSs and BHs and prospects for their detections, the formation and evolution of binary WDs and their observational manifestations. Special attention is given to AM CVn-stars -- compact binaries in which the Roche lobe is filled by another WD or a low-mass partially degenerate helium-star, as these stars are thought to be the best LISA verification binary GW sources.Comment: 105 pages, 18 figure

    Rapid evolution of microbe-mediated protection against pathogens in a worm host.

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    Microbes can defend their host against virulent infections, but direct evidence for the adaptive origin of microbe-mediated protection is lacking. Using experimental evolution of a novel, tripartite interaction, we demonstrate that mildly pathogenic bacteria (Enterococcus faecalis) living in worms (Caenorhabditis elegans) rapidly evolved to defend their animal hosts against infection by a more virulent pathogen (Staphylococcus aureus), crossing the parasitism-mutualism continuum. Host protection evolved in all six, independently selected populations in response to within-host bacterial interactions and without direct selection for host health. Microbe-mediated protection was also effective against a broad spectrum of pathogenic S. aureus isolates. Genomic analysis implied that the mechanistic basis for E. faecalis-mediated protection was through increased production of antimicrobial superoxide, which was confirmed by biochemical assays. Our results indicate that microbes living within a host may make the evolutionary transition to mutualism in response to pathogen attack, and that microbiome evolution warrants consideration as a driver of infection outcome

    Studies on Culture Communication of Confucius Institute

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    新世纪以来,随着中国经济发展、国际地位提升,全球掀起了“中国热”“汉语热”,学习汉语和了解中华文化成为世界风尚,孔子学院正是借鉴国外一些文化推广组织的成功经验,以教授汉语和传播中华文化为目的于2004年应运而生。它致力于世界各国人民对中国语言文化了解,加强中外文化交流,构建和谐世界。成立至今仅有8年,孔子学院在数量上的发展卓有成效,而实际传播效果却尚未达到理想。文化传播实践存在许多问题。学界关于孔子学院文化传播角度的研究不多,对影响孔子学院传播效果的具体因素甚少涉及。因此,为尽快达到孔子学院预期的对外文化传播效果,实现中华文化的有效传播,对孔子学院传播过程各环节、影响因素、存在问题进行研究非常...As China has been gaining power and influence, there arises a craze for the study of China and the Chinese language. The Confucius Institute, following the successful examples of the international culture promotion organizations, was set up in the year 2004, aiming to promote Chinese language and culture. The organization commits to bringing cultural understanding and communication between China a...学位:新闻与传播硕士院系专业:新闻传播学院广告学系_传播学学号:3192009115258

    LEGEND-1000 Preconceptual Design Report

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    We propose the construction of LEGEND-1000, the ton-scale Large Enriched Germanium Experiment for Neutrinoless ββ\beta \beta Decay. This international experiment is designed to answer one of the highest priority questions in fundamental physics. It consists of 1000 kg of Ge detectors enriched to more than 90% in the 76^{76}Ge isotope operated in a liquid argon active shield at a deep underground laboratory. By combining the lowest background levels with the best energy resolution in the field, LEGEND-1000 will perform a quasi-background-free search and can make an unambiguous discovery of neutrinoless double-beta decay with just a handful of counts at the decay QQ value. The experiment is designed to probe this decay with a 99.7%-CL discovery sensitivity in the 76^{76}Ge half-life of 1.3×10281.3\times10^{28} years, corresponding to an effective Majorana mass upper limit in the range of 9-21 meV, to cover the inverted-ordering neutrino mass scale with 10 yr of live time

    Shear Wave Splitting and Mantle Anisotropy: Measurements, Interpretations, and New Directions

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