443 research outputs found

    Does basic science knowledge correlate with clinical reasoning in assessments of first-year medical students?

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    AbstractPrevious research has investigated the outcomes of Problem-based Learning (PBL), but little research has compared competencies in PBL and associated clinical reasoning skills with other competencies in medical education. We used results from formative and summative exams during the first block of medical education to investigate how the performance of beginning, undergraduate medical students on online clinical cases and additional clinical-reasoning questions related to their basic-science knowledge. We found a moderate correlation between clinical-reasoning and basic-science performance. However, the level of correlation suggests that distinct knowledge and skills are involved in clinical reasoning beyond those associated with basic-science knowledge

    KELT-8b: A highly inflated transiting hot Jupiter and a new technique for extracting high-precision radial velocities from noisy spectra

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    We announce the discovery of a highly inflated transiting hot Jupiter discovered by the KELT-North survey. A global analysis including constraints from isochrones indicates that the V = 10.8 host star (HD 343246) is a mildly evolved, G dwarf with Teff=575455+54T_{\rm eff} = 5754_{-55}^{+54} K, logg=4.0780.054+0.049\log{g} = 4.078_{-0.054}^{+0.049}, [Fe/H]=0.272±0.038[Fe/H] = 0.272\pm0.038, an inferred mass M=1.2110.066+0.078M_{*}=1.211_{-0.066}^{+0.078} M_{\odot}, and radius R=1.670.12+0.14R_{*}=1.67_{-0.12}^{+0.14} R_{\odot}. The planetary companion has mass MP=0.8670.061+0.065M_P = 0.867_{-0.061}^{+0.065} MJM_{J}, radius RP=1.860.16+0.18R_P = 1.86_{-0.16}^{+0.18} RJR_{J}, surface gravity loggP=2.7930.075+0.072\log{g_{P}} = 2.793_{-0.075}^{+0.072}, and density ρP=0.1670.038+0.047\rho_P = 0.167_{-0.038}^{+0.047} g cm3^{-3}. The planet is on a roughly circular orbit with semimajor axis a=0.045710.00084+0.00096a = 0.04571_{-0.00084}^{+0.00096} AU and eccentricity e=0.0350.025+0.050e = 0.035_{-0.025}^{+0.050}. The best-fit linear ephemeris is T0=2456883.4803±0.0007T_0 = 2456883.4803 \pm 0.0007 BJDTDB_{\rm TDB} and P=3.24406±0.00016P = 3.24406 \pm 0.00016 days. This planet is one of the most inflated of all known transiting exoplanets, making it one of the few members of a class of extremely low density, highly-irradiated gas giants. The low stellar logg\log{g} and large implied radius are supported by stellar density constraints from follow-up light curves, plus an evolutionary and space motion analysis. We also develop a new technique to extract high precision radial velocities from noisy spectra that reduces the observing time needed to confirm transiting planet candidates. This planet boasts deep transits of a bright star, a large inferred atmospheric scale height, and a high equilibrium temperature of Teq=167555+61T_{eq}=1675^{+61}_{-55} K, assuming zero albedo and perfect heat redistribution, making it one of the best targets for future atmospheric characterization studies.Comment: Submitted to ApJ, feedback is welcom

    Bulk and Interfacial Shear Thinning of Immiscible Polymers

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    Nonequilibrium molecular dynamics simulations are used to study the shear thinning behavior of immiscible symmetric polymer blends. The phase separated polymers are subjected to a simple shear flow imposed by moving a wall parallel to the fluid-fluid interface. The viscosity begins to shear thin at much lower rates in the bulk than at the interface. The entire shear rate dependence of the interfacial viscosity is consistent with a shorter effective chain length ss^* that also describes the width of the interface. This ss^* is independent of chain length NN and is a function only of the degree of immiscibility of the two polymers. Changes in polymer conformation are studied as a function of position and shear rate.Shear thinning correlates more closely with a decrease in the component of the radius of gyration along the velocity gradient than with elongation along the flow. At the interface, this contraction of chains is independent of NN and consistent with the bulk behavior for chains of length ss^*. The distribution of conformational changes along chains is also studied. Central regions begin to stretch at a shear rate that decreases with increasing NN, while shear induced changes at the ends of chains are independent of NN.Comment: 8 pages, 8 figure

    Variations of training load, monotony, and strain and dose-response relationships with maximal aerobic speed, maximal oxygen uptake, and isokinetic strength in professional soccer players

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    This study aimed to identify variations in weekly training load, training monotony, and training strain across a 10-week period (during both, pre- and in-season phases); and to analyze the dose-response relationships between training markers and maximal aerobic speed (MAS), maximal oxygen uptake, and isokinetic strength. Twenty-seven professional soccer players (24.9±3.5 years old) were monitored across the 10-week period using global positioning system units. Players were also tested for maximal aerobic speed, maximal oxygen uptake, and isokinetic strength before and after 10 weeks of training. Large positive correlations were found between sum of training load and extension peak torque in the right lower limb (r = 0.57, 90%CI[0.15;0.82]) and the ratio agonist/antagonist in the right lower limb (r = 0.51, [0.06;0.78]). It was observed that loading measures fluctuated across the period of the study and that the load was meaningfully associated with changes in the fitness status of players. However, those magnitudes of correlations were small-to-large, suggesting that variations in fitness level cannot be exclusively explained by the accumulated load and loading profile

    KELT-12b: A P ∼ 5 day, Highly Inflated Hot Jupiter Transiting a Mildly Evolved Hot Star

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    We announce the discovery of KELT-12b, a highly inflated Jupiter-mass planet transiting the mildly evolved, V = 10.64 host star TYC 2619-1057-1. We followed up the initial transit signal in the KELT-North survey data with precise ground-based photometry, high-resolution spectroscopy, precise radial velocity measurements, and high-resolution adaptive optics imaging. Our preferred best-fit model indicates that the host star has = 6279 ±51 K, = 3.89 ±0.05, [Fe/H] = 0.19+0.08-0.09, = M∗ = 1.59+0.070.09M, and R ∗= 2.37 ±0.17 . The planetary companion has Mp= 0.95 ±0.14 MJ, RP = 1.78+0.17-0.16 RJ, log gP = 2.87+0.9-0.09 and density pp 0.210.070.05= g cm-3, making it one of the most inflated giant planets known. Furthermore, for future follow-up, we report a high-precision time of inferior conjunction in BJDTDB of 2,457,083.660459 ±0.000894 and period of P = 5.0316216 ± 0.000032days. Despite the relatively large separation of ∼0.07 au implied by its ∼5.03-day orbital period, KELT-12b receives significant flux of 2.38+0.32-0.29 × 109 erg s-1 cm-2 from its host. We compare the radii and insolations of transiting gas giant planets around hot (Teff 6250 K) and cool stars, noting that the observed paucity of known transiting giants around hot stars with low insolation is likely due to selection effects. We underscore the significance of long-term ground-based monitoring of hot stars and space-based targeting of hot stars with the Transiting Exoplanet Survey Satellite to search for inflated gas giants in longer-period orbits

    Charged and strange hadron elliptic flow in Cu+Cu collisions at sNN\sqrt{s_{NN}} = 62.4 and 200 GeV

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    We present the results of an elliptic flow analysis of Cu+Cu collisions recorded with the STAR detector at 62.4 and 200GeV. Elliptic flow as a function of transverse momentum is reported for different collision centralities for charged hadrons and strangeness containing hadrons KS0K_{S}^{0}, Λ\Lambda, Ξ\Xi, ϕ\phi in the midrapidity region eta<1.0|eta|<1.0. Significant reduction in systematic uncertainty of the measurement due to non-flow effects has been achieved by correlating particles at midrapidity, η<1.0|\eta|<1.0, with those at forward rapidity, 2.5<η<4.02.5<|\eta|<4.0. We also present azimuthal correlations in p+p collisions at 200 GeV to help estimating non-flow effects. To study the system-size dependence of elliptic flow, we present a detailed comparison with previously published results from Au+Au collisions at 200 GeV. We observe that v2v_{2}(pTp_{T}) of strange hadrons has similar scaling properties as were first observed in Au+Au collisions, i.e.: (i) at low transverse momenta, pT<2GeV/cp_T<2GeV/c, v2v_{2} scales with transverse kinetic energy, mTmm_{T}-m, and (ii) at intermediate pTp_T, 2<pT<4GeV/c2<p_T<4GeV/c, it scales with the number of constituent quarks, nqn_q. We have found that ideal hydrodynamic calculations fail to reproduce the centrality dependence of v2v_{2}(pTp_{T}) for KS0K_{S}^{0} and Λ\Lambda. Eccentricity scaled v2v_2 values, v2/ϵv_{2}/\epsilon, are larger in more central collisions, suggesting stronger collective flow develops in more central collisions. The comparison with Au+Au collisions which go further in density shows v2/ϵv_{2}/\epsilon depend on the system size, number of participants NpartN_{part}. This indicates that the ideal hydrodynamic limit is not reached in Cu+Cu collisions, presumably because the assumption of thermalization is not attained.Comment: 18 pages, 14 figure
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