5,216 research outputs found

    Photon + Jet production at sqrt{s}=1.96 TeV

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    Prompt photon production results by the CDF and D\OCollaborations in the Tevatron Run II at a center of mass energy of s\sqrt{s}=1.96 TeV are presented. Cross sections for central isolated photons, photon+jet production and photons produced in association with a heavy flavor quark are reported. The measurements are compared to Next-to-Leading order perturbative QCD predictions.Comment: 4 pages, 6 figures, Proceedings for the QCD Session at Moriond 200

    Management of Elbow Dislocations in the National Football League.

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    Background: Although much literature exists regarding the treatment and management of elbow dislocations in the general population, little information is available regarding management in the athletic population. Furthermore, no literature is available regarding the postinjury treatment and timing of return to play in the contact or professional athlete. Purpose: To review the clinical course of elbow dislocations in professional football players and determine the timing of return to full participation. Study Design: Case series; Level of evidence, 4. Methods: All National Football League (NFL) athletes with elbow dislocations from 2000 through 2011 who returned to play during the season were identified from the NFL Injury Surveillance System (NFL ISS). Roster position, player activity, use of external bracing, and clinical course were reviewed. Mean number of days lost until full return to play was determined for players with elbow dislocations who returned in the same season. Results: From 2000 to 2011, a total of 62 elbow dislocations out of 35,324 injuries were recorded (0.17%); 40 (64.5%) dislocations occurred in defensive players, 12 (19.4%) were in offensive players; and 10 (16.1%) were during special teams play. Over half of the injuries (33/62, 53.2%) were sustained while tackling, and 4 (6.5%) patients required surgery. A total of 47 (75.8%) players who sustained this injury were able to return in the same season. For this group, the mean number of days lost in players treated conservatively (45/47) was 25.1 days (median, 23.0 days; range, 0.0-118 days), while that for players treated operatively (2/47) was 46.5 days (median, 46.5 days; range, 29-64 days). Mean return to play based on player position was 25.8 days for defensive players (n = 28; median, 21.5 days; range, 3.0-118 days), 24.1 days for offensive players (n = 11; median, 19 days; range, 2.0-59 days), and 25.6 days for special teams players (n = 8; median, 25.5 days; range, 0-44 days). Conclusion: Elbow dislocations comprise less than a half of a percent of all injuries sustained in the NFL. Most injuries occur during the act of tackling, with the majority of injured athletes playing a defensive position. Players treated nonoperatively missed a mean of 25.1 days, whereas those managed operatively missed a mean of 46.5 days

    Temperature and Emission-Measure Profiles Along Long-Lived Solar Coronal Loops Observed with TRACE

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    We report an initial study of temperature and emission measure distributions along four steady loops observed with the Transition Region and Coronal Explorer (TRACE) at the limb of the Sun. The temperature diagnostic is the filter ratio of the extreme-ultraviolet 171-angstrom and 195-angstrom passbands. The emission measure diagnostic is the count rate in the 171-angstrom passband. We find essentially no temperature variation along the loops. We compare the observed loop structure with theoretical isothermal and nonisothermal static loop structure.Comment: 10 pages, 3 postscript figures (LaTeX, uses aaspp4.sty). Accepted by ApJ Letter

    Effect of Concave Wall Geometry on Heat Transfer in Hypersonic Boundary Layers

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    Heat transfer measurements are made to investigate the effects of concave surface curvature on a high-stagnation enthalpy boundary layer in a Mach 5.1 flow. Experiments are carried out using two curved models with 16 and 25 degree turning angles, and baseline planar models (at plate and linear ramp) for comparative study. Streamwise and spanwise cross-sections are obtained. Significant destabilization of the boundary layer is observed over the adverse pressure gradient geometries. For the curved surfaces, the heat flux distribution appears to exhibit a quadratic dependence with streamwise distance, in contrast with the linear dependence observed on the linear ramp

    The Minimum of Solar Cycle 23: As Deep as It Could Be?

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    In this work we introduce a new way of binning sunspot group data with the purpose of better understanding the impact of the solar cycle on sunspot properties and how this defined the characteristics of the extended minimum of cycle 23. Our approach assumes that the statistical properties of sunspots are completely determined by the strength of the underlying large-scale field and have no additional time dependencies. We use the amplitude of the cycle at any given moment (something we refer to as activity level) as a proxy for the strength of this deep-seated magnetic field. We find that the sunspot size distribution is composed of two populations: one population of groups and active regions and a second population of pores and ephemeral regions. When fits are performed at periods of different activity level, only the statistical properties of the former population, the active regions, is found to vary. Finally, we study the relative contribution of each component (small-scale versus large-scale) to solar magnetism. We find that when hemispheres are treated separately, almost every one of the past 12 solar minima reaches a point where the main contribution to magnetism comes from the small-scale component. However, due to asymmetries in cycle phase, this state is very rarely reached by both hemispheres at the same time. From this we infer that even though each hemisphere did reach the magnetic baseline, from a heliospheric point of view the minimum of cycle 23 was not as deep as it could have been

    Distribuzione spaziale dei popolamenti a <i>Lithophyllum byssoides</i>, a <i>Patella ferruginea</i> e della frangia a <i>Cystoseira</i> sp. nell'Arcipelago di La Maddalena (Sardegna-Italia) = Spatial distribution of <i>Lithophyllum byssoides</i>, <i>Patella ferruginea</i> assemblage and <i>Cystoseira</i> sp. fringe in The Maddalena Archipelago (Sardinia-Italy)

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    A study on the distribution of Lithophyllum byssoides, Patella ferruginea and Cystoseira sp. fringe populations, has been carried out in the national Park of the La Maddalena archipelago. Those species has been protected from international conventions as rare species in danger of extinction. The results of the study shows a good conservation state of the examined islands

    Kinetic pinning and biological antifreezes

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    Biological antifreezes protect cold-water organisms from freezing. An example are the antifreeze proteins (AFPs) that attach to the surface of ice crystals and arrest growth. The mechanism for growth arrest has not been heretofore understood in a quantitative way. We present a complete theory based on a kinetic model. We use the `stones on a pillow' picture. Our theory of the suppression of the freezing point as a function of the concentration of the AFP is quantitatively accurate. It gives a correct description of the dependence of the freezing point suppression on the geometry of the protein, and might lead to advances in design of synthetic AFPs.Comment: 4 pages, 4 figure

    The approach to thermalization in the classical phi^4 theory in 1+1 dimensions: energy cascades and universal scaling

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    We study the dynamics of thermalization and the approach to equilibrium in the classical phi^4 theory in 1+1 spacetime dimensions. At thermal equilibrium we exploit the equivalence between the classical canonical averages and transfer matrix quantum traces of the anharmonic oscillator to obtain exact results for the temperature dependence of several observables, which provide a set of criteria for thermalization. We find that the Hartree approximation is remarkably accurate in equilibrium. The non-equilibrium dynamics is studied by numerically solving the equations of motion in light-cone coordinates for a broad range of initial conditions and energy densities.The time evolution is described by several stages with a cascade of energy towards the ultraviolet. After a transient stage, the spatio-temporal gradient terms become larger than the nonlinear term and a stage of universal cascade emerges.This cascade starts at a time scale t_0 independent of the initial conditions (except for very low energy density). Here the power spectra feature universal scaling behavior and the front of the cascade k(t) grows as a power law k(t) sim t^alpha with alpha lesssim 0.25. The wake behind the cascade is described as a state of Local Thermodynamic Equilibrium (LTE) with all correlations being determined by the equilibrium functional form with an effective time dependent temperatureTeff(t) which slowly decreases as sim t^{-alpha}.Two well separated time scales emerge while Teff(t) varies slowly, the wavectors in the wake with k < k(t) attain LTE on much shorter time scales.This universal scaling stage ends when the front of the cascade reaches the cutoff at a time t_1 sim a^{-1/alpha}. Virialization starts to set much earlier than LTE. We find that strict thermalization is achieved only for an infinite time scale.Comment: relevance for quantum field theory discussed providing validity criteria. To appear in Phys. Rev.

    Contemplative Science: An Insider's Prospectus

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    This chapter describes the potential far‐reaching consequences of contemplative higher education for the fields of science and medicine
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