1,024 research outputs found

    Minimal affinizations as projective objects

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    We prove that the specialization to q=1 of a Kirillov-Reshetikhin module for an untwisted quantum affine algebra of classical type is projective in a suitable category. This yields a uniform character formula for the Kirillov-Reshetikhin modules. We conjecture that these results holds for specializations of minimal affinization with some restriction on the corresponding highest weight. We discuss the connection with the conjecture of Nakai and Nakanishi on q-characters of minimal affinizations. We establish this conjecture in some special cases. This also leads us to conjecture an alternating sum formula for Jacobi-Trudi determinants.Comment: 25 page

    The Effects of a Closed-Chain, Eccentric Training Program on Hamstring Injuries of a Professional Football Cheerleading Team

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    Objective Hamstring injuries are a common occurrence among professional football cheerleaders. The purpose of this study is to identify the effects of an eccentric, closed-chain hamstring exercise intervention on hamstring injury–associated pain during the course of the football season among professional football cheerleaders. Methods Forty-three female cheerleaders participated in an eccentric, closed-chain hamstring exercise intervention protocol provided by doctors of chiropractic that incorporated loops of elastic-band or Thera-Band Loops (Hygenic Corporation, Akron, OH) during practice and at home during the regular football season. Hamstring injury–related pain was assessed in June, during team selection; in September, at the start of the season; and in December, at the end of season. No intervention was applied between June and September, although the sample participated in 4 hours of practice 2 to 3 times per week. The intervention was applied to the entire sample regardless of hamstring injury–related pain during the regular football season between September and December. The interventions included 2 exercises and were completed bilaterally 2 times per week at each biweekly practice and were encouraged to be done at least 3 additional times per week at home on nonpractice days. Results Among the subsample who reported hamstring-related injury pain between June and September, the exercise intervention significantly decreased (P \u3c .007) pain between September (6.07 ± 0.58) and December (3.67 ± 0.65). Conclusions The eccentric, closed-chain hamstring exercise intervention reduced hamstring injury–related pain among this group of professional football cheerleaders

    Sleep Characteristics in Patients with Whiplash-Associated Disorders: A Descriptive Study

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    Study Objectives: The purpose of this study was to explore sleep habits and characteristics of patients with whiplash-associated disorders (WAD) presenting at an outpatient, chiropractic clinic using the Medical Outcomes Study (MOS) Sleep Scale. Methods: Fifty-one patients from an outpatient chiropractic and physical therapy clinic specializing in spinal rehabilitation participated in this cross-sectional, descriptive study. Data were collected using a descriptive survey, the Visual Analog Scale (VAS), the Neck Disability Index (NDI), and the self-administered 12-item MOS Sleep Scale. Data analysis included descriptive statistics to describe pain, disability, and sleep characteristics of the study sample, and computation of confidence intervals to determine differences in means of sleep characteristics between the non-WAD population (as determined by previous studies) and the study sample of WAD patients. Results: Results indicate that when compared to normative values of the non-WAD population, the sample of WAD patients in this study presents with significantly greater measures of neck disability (NDI), neck pain (VAS), sleep disturbance, snoring, shortness of breath and headache, sleep somnolence and sleep problems index I and II. This sample also presents with significantly lower measures of optimal sleep when compared to the general population. Conclusion: Consistent with previous research, findings from this study indicate that WAD patients have increased neck disability and pain, and poorer sleep outcomes, indicating the need for clinicians to assess sleep characteristics and incorporate interventions aimed at alleviating these symptoms when planning rehabilitation. Findings provide evidence for the need to further explore sleep disturbances among WAD patients to establish a stronger understanding of the course and prognosis of this condition

    Representations of Double Affine Lie algebras

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    We study representations of the double affine Lie algebra associated to a simple Lie algebra. We construct a family of indecomposable integrable representations and identify their irreducible quotients. We also give a condition for the indecomposable modules to be irreducible, this is analogous to a result in the representation theory of quantum affine algebras. Finally, in the last section of the paper, we show, by using the notion of fusion product, that our modules are generically reducible

    Multiple Current States of Two Phase-Coupled Superconducting Rings

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    The states of two phase-coupled superconducting rings have been investigated. Multiple current states have been revealed in the dependence of the critical current on the magnetic field. The performed calculations of the critical currents and energy states in a magnetic field have made it possible to interpret the experiment as the measurement of energy states into which the system comes with different probabilities because of the equilibrium and non-equilibrium noises upon the transition from the resistive state to the superconducting state during the measurement of the critical currentComment: 5 pages, 5 figure

    EPR before EPR: a 1930 Einstein-Bohr thought experiment revisited

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    In 1930 Einstein argued against consistency of the time-energy uncertainty relation by discussing a thought experiment involving a measurement of mass of the box which emitted a photon. Bohr seemingly triumphed over Einstein by arguing that the Einstein's own general theory of relativity saves the consistency of quantum mechanics. We revisit this thought experiment from a modern point of view at a level suitable for undergraduate readership and find that neither Einstein nor Bohr was right. Instead, this thought experiment should be thought of as an early example of a system demonstrating nonlocal "EPR" quantum correlations, five years before the famous Einstein-Podolsky-Rosen paper.Comment: 11 pages, revised, accepted for publication in Eur. J. Phy

    Observations of three slow glitches in the spin rate of the pulsar B1822-09

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    Three slow glitches in the rotation rate of the pulsar B1822-09 were revealed over the 1995-2004 interval. The slow glitches observed are characterized by a gradual increase in the rotation frequency with a long timescale of several months, accompanied by a rapid decrease in the magnitude of the frequency first derivative by 1-2 per cent of the initial value and subsequent exponential increase back to its initial value on the same timescale. The cumulative fractional increase in the pulsar rotation rate for the three glitches amounts to Delta_nu/nu ~ 7 10^{-8}.Comment: 11 pages, 3 figures. Accepted for publication in MNRA

    Quantum mechanics explained

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    The physical motivation for the mathematical formalism of quantum mechanics is made clear and compelling by starting from an obvious fact - essentially, the stability of matter - and inquiring into its preconditions: what does it take to make this fact possible?Comment: 29 pages, 5 figures. v2: revised in response to referee comment

    Vitamins A & D Inhibit the Growth of Mycobacteria in Radiometric Culture

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    The role of vitamins in the combat of disease is usually conceptualized as acting by modulating the immune response of an infected, eukaryotic host. We hypothesized that some vitamins may directly influence the growth of prokaryotes, particularly mycobacteria. complex).Vitamins A and D cause dose-dependent inhibition of all three mycobacterial species studied. Vitamin A is consistently more inhibitory than vitamin D. The vitamin A precursor, β-carotene, is not inhibitory, whereas three vitamin A metabolites cause inhibition. Vitamin K has no effect. Vitamin E causes negligible inhibition in a single strain.We show that vitamin A, its metabolites Retinyl acetate, Retinoic acid and 13-cis Retinoic acid and vitamin D directly inhibit mycobacterial growth in culture. These data are compatible with the hypothesis that complementing the immune response of multicellular organisms, vitamins A and D may have heretofore unproven, unrecognized, independent and probable synergistic, direct antimycobacterial inhibitory activity

    The Chandra LETGS high resolution X-ray spectrum of the isolated neutron star RX J1856.5-3754

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    We present the Chandra LETGS X-ray spectrum of the nearby (~60 pc) neutron star RX J1856.5-3754. Detailed spectral analysis of the combined X-ray and optical data rules out the nonmagnetic neutron star atmosphere models with hydrogen, helium, iron and solar compositions. We also conclude that strongly magnetized atmosphere models are unable to represent the data. The data can be explained with a two-component blackbody model. The harder component with temperature of kT_bb~63 eV and a radius R_bb~2.2 km of the emitting region well fits the X-ray data and can be interpreted as radiation from a hot region on the star's surface.Comment: 4 pages, 3 color figures; acceped by A&A Letters; http://www.xray.mpe.mpg.de/~burwitz/burwitz_refereed.htm
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