985 research outputs found

    Scaling-violation phenomena and fractality in the human posture control systems

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    By analyzing the movements of quiet standing persons by means of wavelet statistics, we observe multiple scaling regions in the underlying body dynamics. The use of the wavelet-variance function opens the possibility to relate scaling violations to different modes of posture control. We show that scaling behavior becomes close to perfect, when correctional movements are dominated by the vestibular system.Comment: 12 pages, 4 figures, to appear in Phys. Rev.

    Sea quark effects in B Spectroscopy and Decay Constants

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    We present comprehensive results for the spectrum and decay constants of hadrons containing a single b quark. The heavy quark is simulated using an O(1/M)O(1/M) NRQCD action and the light quark using the O(a)O(a) tadpole-improved clover action on gauge configurations containing two degenerate flavours of sea quarks at ÎČnf=2=5.6\beta^{n_f=2}=5.6 provided by the HEMCGC collaboration. We present detailed results for the lower lying SS and PP wave BB meson states and the Λb\Lambda_b baryon. We find broad agreement with experiment. In addition, we present results for the pseudoscalar and, for the first time, the vector decay constants fully consistent to O(α/M):fB=186(5)(stat)(19)(pert)(9)(disc)(13)(NRQCD)(+50)(a−1)MeV,fB∗=181(6)(stat)(18)(pert)(9)(disc)(13)(NRQCD)(+55)(a−1)MeVO(\alpha/M): f_B = 186(5)(stat)(19)(pert)(9)(disc)(13)(NRQCD)(+50)(a^{-1})MeV, f_B^* = 181(6) (stat)(18)(pert)(9)(disc)(13)(NRQCD)(+55)(a^{-1})MeV and fBs/fB=1.14(2)(stat)(−2)(Îșs)f_{B_s}/f_B = 1.14(2)(stat)(-2)(\kappa_s). We present an investigation of sea quark effects in the BB spectrum and decay constants. We compare our results with those from similar quenched simulations at ÎČnf=0=6.0\beta^{n_f=0}=6.0. For the spectrum, the quenched results reproduce the experimental spectrum well and there is no significant difference between the quenched and nf=2n_f=2 results. For the decay constants, our results suggest that sea quark effects may be large. We find that fBf_B increases by approximately 25% between nf=0n_f=0 and nf=2n_f=2.Comment: 49 pages, 16 figures, revtex, the discussion of systematic errors and the comparison of the pseudoscalar decay constant at nf=0 and nf=2 has been expande

    Temperature and Polarization Patterns in Anisotropic Cosmologies

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    We study the coherent temperature and polarization patterns produced in homogeneous but anisotropic cosmological models. We show results for all Bianchi types with a Friedman-Robertson-Walker limit (i.e. Types I, V, VII0_{0}, VIIh_{h} and IX) to illustrate the range of possible behaviour. We discuss the role of spatial curvature, shear and rotation in the geodesic equations for each model and establish some basic results concerning the symmetries of the patterns produced. We also give examples of the time-evolution of these patterns in terms of the Stokes parameters II, QQ and UU.Comment: 24 pages, 7 Figures, submitted to JCAP. Revised version: numerous references added, text rewritten, and errors corrected

    The dual parametrization for gluon GPDs

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    We consider the application of the dual parametrization for the case of gluon GPDs in the nucleon. This provides opportunities for the more flexible modeling unpolarized gluon GPDs in a nucleon which in particular contain the invaluable information on the fraction of nucleon spin carried by gluons. We perform the generalization of Abel transform tomography approach for the case of gluons. We also discuss the skewness effect in the framework of the dual parametrization. We strongly suggest to employ the fitting strategies based on the dual parametrization to extract the information on GPDs from the experimental data.Comment: 37 pages, 2 figure

    Comparative Study of full QCD Hadron Spectrum and Static Quark Potential with Improved Actions

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    We investigate effects of action improvement on the light hadron spectrum and the static quark potential in two-flavor QCD for a−1≈1a^{-1} \approx 1 GeV and mPS/mV=0.7−0.9m_{PS}/m_V = 0.7-0.9. We compare a renormalization group improved action with the plaquette action for gluons, and the SW-clover action with the Wilson action for quarks. We find a significant improvement in the hadron spectrum by improving the quark action, while the gluon improvement is crucial for a rotationally invariant static potential. We also explore the region of light quark masses corresponding to mPS/mV≄0.4m_{PS}/m_V \geq 0.4 on a 2.7 fm lattice using the improved gauge and quark action. A flattening of the potential is not observed up to 2 fm.Comment: LaTeX, 35 pages, 22 eps figures, uses revtex and eps

    Race and sex differences in dropout from the STRRIDE trials

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    Purpose: To determine if race and sex differences exist in determinants and timing of dropout among individuals enrolled in an exercise and/or caloric restriction intervention. Methods: A total of 947 adults with dyslipidemia (STRRIDE I, STRRIDE AT/RT) or prediabetes (STRRIDE-PD) were randomized to either inactive control or to 1 of 10 exercise interventions, ranging from doses of 8–23 kcal/kg/week, intensities of 50%–75% (Formula presented.) peak, and durations of 6–8 months. Two groups included resistance training, and one included a dietary intervention (7% weight loss goal). Dropout was defined as an individual withdrawn from the study, with the reasons for dropout aggregated into determinant categories. Timing of dropout was defined as the last session attended and aggregated into phases (i.e., “ramp” period to allow gradual adaptation to exercise prescription). Utilizing descriptive statistics, percentages were generated according to categories of determinants and timing of dropout to describe the proportion of individuals who fell within each category. Results: Black men and women were more likely to be lost to follow-up (Black men: 31.3% and Black women: 19.6%), or dropout due to work responsibilities (15.6% and 12.5%), “change of mind” (12.5% and 8.9%), transportation issues (6.3% and 3.6%), or reported lack of motivation (6.3% and 3.6%). Women in general noted lack of time more often than men as a reason for dropout (White women: 22.4% and Black women: 22.1%). Regardless of race and sex, most participants dropped out during the ramp period of the exercise intervention; with Black women (50%) and White men (37.1%) having the highest dropout rate during this period. Conclusion: These findings emphasize the importance of targeted retention strategies when aiming to address race and sex differences that exist in determinants and timing of dropout among individuals enrolled in an exercise and/or caloric restriction intervention

    Scaling critical behavior of superconductors at zero magnetic field

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    We consider the scaling behavior in the critical domain of superconductors at zero external magnetic field. The first part of the paper is concerned with the Ginzburg-Landau model in the zero magnetic field Meissner phase. We discuss the scaling behavior of the superfluid density and we give an alternative proof of Josephson's relation for a charged superfluid. This proof is obtained as a consequence of an exact renormalization group equation for the photon mass. We obtain Josephson's relation directly in the form ρs∌tÎœ\rho_{s}\sim t^{\nu}, that is, we do not need to assume that the hyperscaling relation holds. Next, we give an interpretation of a recent experiment performed in thin films of YBa2Cu3O7−ήYBa_{2}Cu_{3}O_{7-\delta}. We argue that the measured mean field like behavior of the penetration depth exponent Îœâ€Č\nu' is possibly associated with a non-trivial critical behavior and we predict the exponents Îœ=1\nu=1 and α=−1\alpha=-1 for the correlation lenght and specific heat, respectively. In the second part of the paper we discuss the scaling behavior in the continuum dual Ginzburg-Landau model. After reviewing lattice duality in the Ginzburg-Landau model, we discuss the continuum dual version by considering a family of scalings characterized by a parameter ζ\zeta introduced such that mh,02∌tζm_{h,0}^2\sim t^{\zeta}, where mh,0m_{h,0} is the bare mass of the magnetic induction field. We discuss the difficulties in identifying the renormalized magnetic induction mass with the photon mass. We show that the only way to have a critical regime with Îœâ€Č=Μ≈2/3\nu'=\nu\approx 2/3 is having ζ≈4/3\zeta\approx 4/3, that is, with mh,0m_{h,0} having the scaling behavior of the renormalized photon mass.Comment: RevTex, 15 pages, no figures; the subsection III-C has been removed due to a mistak

    Constraining the Power Spectrum using Clusters

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    (Shortened Abstract). We analyze a redshift sample of Abell/ACO clusters and compare them with numerical simulations based on the truncated Zel'dovich approximation (TZA), for a list of eleven dark matter (DM) models. For each model we run several realizations, on which we estimate cosmic variance effects. We analyse correlation statistics, the probability density function, and supercluster properties from percolation analysis. As a general result, we find that the distribution of galaxy clusters provides a constraint only on the shape of the power spectrum, but not on its amplitude: a shape parameter 0.18 < \Gamma < 0.25 and an effective spectral index at 20Mpc/h in the range [-1.1,-0.9] are required by the Abell/ACO data. In order to obtain complementary constraints on the spectrum amplitude, we consider the cluster abundance as estimated using the Press--Schechter approach, whose reliability is explicitly tested against N--body simulations. We conclude that, of the cosmological models considered here, the only viable models are either Cold+Hot DM ones with \Omega_\nu = [0.2-0.3], better if shared between two massive neutrinos, and flat low-density CDM models with \Omega_0 = [0.3-0.5].Comment: 37 pages, Latex file, 9 figures; New Astronomy, in pres

    Heavy quarkonium: progress, puzzles, and opportunities

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    A golden age for heavy quarkonium physics dawned a decade ago, initiated by the confluence of exciting advances in quantum chromodynamics (QCD) and an explosion of related experimental activity. The early years of this period were chronicled in the Quarkonium Working Group (QWG) CERN Yellow Report (YR) in 2004, which presented a comprehensive review of the status of the field at that time and provided specific recommendations for further progress. However, the broad spectrum of subsequent breakthroughs, surprises, and continuing puzzles could only be partially anticipated. Since the release of the YR, the BESII program concluded only to give birth to BESIII; the BB-factories and CLEO-c flourished; quarkonium production and polarization measurements at HERA and the Tevatron matured; and heavy-ion collisions at RHIC have opened a window on the deconfinement regime. All these experiments leave legacies of quality, precision, and unsolved mysteries for quarkonium physics, and therefore beg for continuing investigations. The plethora of newly-found quarkonium-like states unleashed a flood of theoretical investigations into new forms of matter such as quark-gluon hybrids, mesonic molecules, and tetraquarks. Measurements of the spectroscopy, decays, production, and in-medium behavior of c\bar{c}, b\bar{b}, and b\bar{c} bound states have been shown to validate some theoretical approaches to QCD and highlight lack of quantitative success for others. The intriguing details of quarkonium suppression in heavy-ion collisions that have emerged from RHIC have elevated the importance of separating hot- and cold-nuclear-matter effects in quark-gluon plasma studies. This review systematically addresses all these matters and concludes by prioritizing directions for ongoing and future efforts.Comment: 182 pages, 112 figures. Editors: N. Brambilla, S. Eidelman, B. K. Heltsley, R. Vogt. Section Coordinators: G. T. Bodwin, E. Eichten, A. D. Frawley, A. B. Meyer, R. E. Mitchell, V. Papadimitriou, P. Petreczky, A. A. Petrov, P. Robbe, A. Vair

    Are Patellofemoral Joint Alignment and Shape Associated With Structural Magnetic Resonance Imaging Abnormalities and Symptoms Among People With Patellofemoral Pain?

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    BACKGROUND:: Patellofemoral malalignment has been observed among people with patellofemoral pain (PFP) and may be associated with the presence of imaging features of osteoarthritis, symptoms, and function.PURPOSE:: To determine whether patellofemoral joint alignment and bony shape are associated with (1) cartilage, bone, and soft tissue morphological abnormalities defined on magnetic resonance imaging (MRI) and (2) reported symptoms and function among people with PFP.STUDY DESIGN:: Cross-sectional study; Level of evidence, 3.METHODS:: Participants (mean ± SD age, 30.2 ± 9.5 years; range, 14-50 years; 78 females, 58.6%) completed questionnaires regarding demographics, pain, symptoms, and function and underwent a 3-T MRI scan of their more symptomatic eligible knee. Structural MRI abnormalities were scored with the MOAKS (Magnetic Resonance Imaging Osteoarthritis Knee Score), and MRI alignment and shape were measured with standardized methods. Associations among MOAKS features, PFP symptoms, and alignment and shape measures were evaluated with regression analyses (α = .05).RESULTS:: Minor cartilage defects were present in 22 (16.5%) participants, patellar osteophytes in 83 (62.4%), anterior femur osteophytes in 29 (21.8%), Hoffa synovitis in 81 (60.9%), and prefemoral fat pad synovitis in 49 (36.8%). A larger Insall-Salvati ratio was significantly associated with the presence of patellar osteophytes (odds ratio [OR], 51.82; 95% CI, 4.20-640.01), Hoffa synovitis (OR, 60.37; 95% CI, 4.66-782.61), and prefemoral fat pad synovitis (OR, 43.31; 95% CI, 4.28-438.72) in the patellofemoral joint. A larger patellar tilt angle was significantly associated with the presence of minor cartilage defects (OR, 1.10; 95% CI, 1.00-1.20), the presence of patellar osteophytes (OR 1.12; 95%CI 1.02-1.22), and prefemoral fat pad synovitis (OR, 1.11; 95% CI, 1.03-1.20) in the patellofemoral joint. Finally, a larger bisect offset was significantly associated with the presence of minor cartilage defects (OR, 1.05; 95% CI, 1.00-1.11) and patellar osteophytes (OR, 1.07; 95% CI, 1.01-1.14) in the patellofemoral joint. The majority of patellofemoral alignment measures were not associated with symptoms or function.CONCLUSION:: For people with PFP, the presence of morphological abnormalities defined on MRI appears to be related to particular patellofemoral alignment measures, including higher Insall-Salvati ratio (indicating patella alta), larger patellar tilt angle (indicating greater lateral tilt), and larger bisect offset (indicating greater lateral displacement). Hardly any associations were found with symptoms or function.
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