4,950 research outputs found

    An Integrated Approach for Evaluating Students' Achievement of Clinical Objectives

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    During the clinical phase of undergraduate medical education (UME) students are often geographically dispersed and assigned to preceptors throughout the community. Monitoring, documenting, and evaluating their clinical experiences and achievement of clinical objectives in this venue becomes a challenge, especially for large UME programs. The purpose of this manuscript is to discuss a method for developing and implementing a school-wide evaluation system for the clinical phase of UME. This type of evaluation system links students' clinical experiential data with the objectives of a clerkship, using technological advances, such as the Personal Digital Assistant (PDA), Internet, and intranet. Clerkship directors are provided real-time reports on student's progress toward achieving clerkship objectives and are able to monitor the clinical activities of the clerkship. Students on the other hand, will be empowered to take more control of their educational experiences by monitoring their own progress

    On the pumping of the CS(v=0v=0) masers in W51 e2e

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    We present the results of numerically solving the rate equations for the first 31 rotational states of CS in the ground vibrational state to determine the conditions under which the J=1-0, J=2-1 and J=3-2 transitions are inverted to produce maser emission. The essence of our results is that the CS(v=0v=0) masers are collisionally pumped and that, depending on the spectral energy distribution, dust emission can suppress the masers. Apart from the J=1-0 and J=2-1 masers the calculations also show that the J=3-2 transition can be inverted to produce maser emission. It is found that beaming is necessary to explain the observed brightness temperatures of the recently discovered CS masers in W51 e2e. The model calculations suggest that a CS abundance of a few times 10−510^{-5} and CS(v=0v=0) column densities of the order 1016 cm−210^{16}\,\mathrm{cm^{-2}} are required for these masers. The rarity of the CS masers in high mass star forming regions might be the result of a required high CS abundance as well as due to attenuation of the maser emission inside as well as outside of the hot core.Comment: 13 pages, 15 figure

    Feedback from massive stars at low metallicities : MUSE observations of N44 and N180 in the Large Magellanic Cloud

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    Accepted for publication in MNRAS, 27 pages, 21 figuresWe present MUSE integral field data of two HII region complexes in the Large Magellanic Cloud (LMC), N44 and N180. Both regions consist of a main superbubble and a number of smaller, more compact HII regions that formed on the edge of the superbubble. For a total of 11 HII regions, we systematically analyse the radiative and mechanical feedback from the massive O-type stars on the surrounding gas. We exploit the integral field property of the data and the coverage of the HeIIλ\lambda5412 line to identify and classify the feedback-driving massive stars, and from the estimated spectral types and luminosity classes we determine the stellar radiative output in terms of the ionising photon flux Q0Q_{0}. We characterise the HII regions in terms of their sizes, morphologies, ionisation structure, luminosity and kinematics, and derive oxygen abundances via emission line ratios. We analyse the role of different stellar feedback mechanisms for each region by measuring the direct radiation pressure, the pressure of the ionised gas, and the pressure of the shock-heated winds. We find that stellar winds and ionised gas are the main drivers of HII region expansion in our sample, while the direct radiation pressure is up to three orders of magnitude lower than the other terms. We relate the total pressure to the star formation rate per unit area, ΣSFR\Sigma_{SFR}, for each region and find that stellar feedback has a negative effect on star formation, and sets an upper limit to ΣSFR\Sigma_{SFR} as a function of increasing pressure.Peer reviewe

    VLASSICK: The VLA Sky Survey in the Central Kiloparsec

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    At a distance of 8 kpc, the center of our Galaxy is the nearest galactic nucleus, and has been the subject of numerous key projects undertaken by great observatories such as Chandra, Spitzer, and Herschel. However, there are still no surveys of molecular gas properties in the Galactic center with less than 30" (1 pc) resolution. There is also no sensitive polarization survey of this region, despite numerous nonthermal magnetic features apparently unique to the central 300 parsecs. In this paper, we outline the potential the VLASS has to fill this gap. We assess multiple considerations in observing the Galactic center, and recommend a C-band survey with 10 micro-Jy continuum RMS and sensitive to molecular gas with densities greater than 10^4 cm^{-3}, covering 17 square degrees in both DnC and CnB configurations ( resolution ~5"), totaling 750 hours of observing time. Ultimately, we wish to note that the upgraded VLA is not just optimized for fast continuum surveys, but has a powerful correlator capable of simultaneously observing continuum emission and dozens of molecular and recombination lines. This is an enormous strength that should be fully exploited and highlighted by the VLASS, and which is ideally suited for surveying the center of our Galaxy.Comment: 13 pages, 3 figures, a White Paper submitted to provide input in planning the Very Large Array Sky Surve

    A sensitized ENU mutagenesis screen for dominant genetic modifiers of thrombosis in the factor V Leiden mouse

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    Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/106086/1/jth05193.pd

    Hypervelocity Stars: Predicting the Spectrum of Ejection Velocities

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    The disruption of binary stars by the tidal field of the black hole in the Galactic Center can produce the hypervelocity stars observed in the halo. We use numerical models to simulate the full spectrum of observable velocities of stars ejected into the halo by this binary disruption process. Our model includes a range of parameters for binaries with 3-4 M_Solar primaries, consideration of radial orbits of the ejected stars through an approximate mass distribution for the Galaxy, and the impact of stellar lifetimes. We calculate the spectrum of ejection velocities and reproduce previous results for the mean ejection velocity at the Galactic center. The model predicts that the full population of ejected stars includes both the hypervelocity stars with velocities large enough to escape from the Galaxy and a comparable number of ejected, but bound, stars of the same stellar type. The predicted median speeds of the population of ejected stars as a function of distance in the halo are consistent with current observations. Combining the model with the data also shows that interesting constraints on the properties of binaries in the Galactic Center and on the mass distribution in the Galaxy can be obtained even with modest samples of ejected stars.Comment: 26 pages, including 6 figures, accepted for publication in the Astrophysical Journa
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