11,589 research outputs found

    Automatic analysis of Swift-XRT data

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    The Swift spacecraft detects and autonomously observes ~100 Gamma Ray Bursts (GRBs) per year, ~96% of which are detected by the X-ray telescope (XRT). GRBs are accompanied by optical transients and the field of ground-based follow-up of GRBs has expanded significantly over the last few years, with rapid response instruments capable of responding to Swift triggers on timescales of minutes. To make the most efficient use of limited telescope time, follow-up astronomers need accurate positions of GRBs as soon as possible after the trigger. Additionally, information such as the X-ray light curve, is of interest when considering observing strategy. The Swift team at Leicester University have developed techniques to improve the accuracy of the GRB positions available from the XRT, and to produce science-grade X-ray light curves of GRBs. These techniques are fully automated, and are executed as soon as data are available.Comment: 4 pages, 2 figures, to appear in the proceedings of ADASS XVII (ASP Conference Series

    Evaluating coasean bargaining experiments with meta-analysis

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    While the Coase Theorem has been a touchstone for understanding bargaining behavior, it has also been criticized for relying on unrealistic assumptions. In response, a line of experimental research analyzes bargaining behavior in laboratory settings. This paper uses meta-analysis to evaluate the Coasean bargaining literature by modeling the probability of an efficient bargain as a function of: (1) measures of transaction costs and related variables, and (2) measures of the social dimensions of a bargain. Results suggest that efficient solutions are more likely when explicit transaction costs do not exist, in the absence of a binding time limit, and when participants have perfect information on payoff schedules. Social dimension variables are found to have the potential to affect bargaining outcomes and are an important avenue for further research.Coase Theorem

    Inversion of spinning sound fields

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    A method is presented for the reconstruction of rotating monopole source distributions using acoustic pressures measured on a sideline parallel to the source axis. The method requires no \textit{a priori} assumptions about the source other than that its strength at the frequency of interest vary sinusoidally in azimuth on the source disc so that the radiated acoustic field is composed of a single circumferential mode. When multiple azimuthal modes are present, the acoustic field can be decomposed into azimuthal modes and the method applied to each mode in sequence. The method proceeds in two stages, first finding an intermediate line source derived from the source distribution and then inverting this line source to find the radial variation of source strength. A far-field form of the radiation integrals is derived, showing that the far field pressure is a band-limited Fourier transform of the line source, establishing a limit on the quality of source reconstruction which can be achieved using far-field measurements. The method is applied to simulated data representing wind-tunnel testing of a ducted rotor system (tip Mach number~0.74) and to control of noise from an automotive cooling fan (tip Mach number~0.14), studies which have appeared in the literature of source identification.Comment: Revised version of paper submitted to JASA; five more figures; expanded content with more discussion of error behaviour and relation to Nearfield Acoustical Holograph

    Helical recorder

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    Tape recorder, using metallic tape, has a minimum of moving parts and no belts. It permits long-term bulk storage in extreme environments, and has less weight and bulk than present recording equipment

    Ferromagnetically coupled dimers on the distorted Shastry-Sutherland lattice: Application to (CuCl)LaNb2O7

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    A recent study [Tassel {\it et al.}, Phys. Rev. Lett. {\bf 105}, 167205 (2010)] has proposed a remarkable spin model for (CuCl)LaNb2O7, in which dimers are ferromagnetically coupled to each other on the distorted Shastry-Sutherland lattice. In this model, the intra-dimer exchange coupling J>0 is antiferromagnetic, while the inter-dimer exchange couplings are ferromagnetic and take different values, J_x,J_y<0, in the two bond directions. Anticipating that the highly frustrated character of this model may lead to a wide range of behaviors in (CuCl)LaNb2O7 and related compounds, we theoretically investigate the ground state phase diagram of this model in detail using the following three approaches: a strong-coupling expansion for small J_x and J_y, exact diagonalization for finite clusters, and a Schwinger boson mean field theory. When |J_x|, |J_y| <~ J, the system stays in a dimer singlet phase with a finite spin gap. This state is adiabatically connected to the decoupled-dimer limit J_x=J_y=0. We show that the magnetization process of this phase depends crucially on the spatial anisotropy of the inter-dimer couplings. The magnetization shows a jump or a smooth increase for weak and strong anisotropy, respectively, after the spin gap closes at a certain magnetic field. When |J_x| or |J_y| >~ J, quantum phase transitions to various magnetically ordered phases (ferromagnetic, collinear stripe, and spiral) occur. The Schwinger boson analysis demonstrates that quantum fluctuations split the classical degeneracy of different spiral ground states. Implications for (CuCl)LaNb2O7 and related compounds are discussed in light of our theoretical results and existing experimental data.Comment: 21 pages, 20 figure

    The Value of Comparative Animal Research : Krogh’s Principle Facilitates Scientific Discoveries

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    There are no conflicts of interest to declare. This paper developed from the 2016 Early Career Impact Award from the Federation of Associations in Behavioral & Brain Sciences to TJS. TJS has received funding from The Leverhulme Trust. FJPE is in receipt of funding from the BBSRC (BB/M001555/1). The National Institutes of Health has funded RDF (NS 034950, NS093277, NIMH 087930), AGO (HD079573, IOS-1354760) and AMK (HD081959). BAA is an Arnold O. Beckman postdoctoral fellow.Peer reviewedPostprin

    Athletic pubalgia and associated rehabilitation

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    BACKGROUND: Evaluation and treatment of groin pain in athletes is challenging. The anatomy is complex, and multiple pathologies often coexist. Different pathologies may cause similar symptoms, and many systems can refer pain to the groin. Many athletes with groin pain have tried prolonged rest and various treatment regimens, and received differing opinions as to the cause of their pain. The rehabilitation specialist is often given a non-specific referral of groin pain or sports hernia. The cause of pain could be as simple as the effects of an adductor strain, or as complex as athletic pubalgia or inguinal disruption. The term sports hernia is starting to be replaced with more specific terms that better describe the injury. Inguinal disruption is used to describe the syndromes related to the injury of the inguinal canal soft tissue environs ultimately causing the pain syndrome. The term athletic pubalgia is used to describe the disruption and/or separation of the more medial common aponeurosis from the pubis, usually with some degree of adductor tendon pathology. TREATMENT: Both non-operative and post-operative treatment options share the goal of returning the athlete back to pain free activity. There is little research available to reference for rehabilitation guidelines and creation of a plan of care. Although each surgeon has their own specific set of post-operative guidelines, some common concepts are consistent among most surgeons. Effective rehabilitation of the high level athlete to pain free return to play requires addressing the differences in the biomechanics of the dysfunction when comparing athletic pubalgia and inguinal disruption. CONCLUSION: Proper evaluation and diagnostic skills for identifying and specifying the difference between athletic pubalgia and inguinal disruption allows for an excellent and efficient rehabilitative plan of care. Progression through the rehabilitative stages whether non-operative or post-operative allows for a focused rehabilitative program. As more information is obtained through MRI imaging and the diagnosis and treatment of inguinal disruption and athletic pubalgia becomes increasingly frequent, more research is warranted in this field to better improve the evidence based practice and rehabilitation of patients. LEVELS OF EVIDENCE: 5
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