13,614 research outputs found

    The Right to Challenge the Accuracy of Breath Test Results Under Alaska Law

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    Section 28.90.020 of the Alaska Statutes provides that in prosecutions for drunk driving, if an offense described under this title requires that a chemical test of a person\u27s breath produce a particular result, and the chemical test is administered by a properly calibrated instrument approved by the Department of Public Safety, the result described by statute is not affected by the instrument\u27s working tolerance. This provision appears to prohibit the defense from calling into question the accuracy of a breath test by introducing evidence of uncertainty inherent in the testing procedure. The statute is problematic because due process requires that defendants be permitted to challenge the evidence presented against them. Moreover, there is a strong argument that basing conviction on a single breath sample that is within a known margin of error is a per se violation of due process, as it bases guilt or innocence on a purely fortuitous result. This Article examines the issues with Alaska\u27s statute and proposes using multiple breath tests as a simple, cost-effective solution to this potential abuse of due process

    Star Formation in Transient Molecular Clouds

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    We present the results of a numerical simulation in which star formation proceeds from an initially unbound molecular cloud core. The turbulent motions, which dominate the dynamics, dissipate in shocks leaving a quiescent region which becomes gravitationally bound and collapses to form a small multiple system. Meanwhile, the bulk of the cloud escapes due to its initial supersonic velocities. In this simulation, the process naturally results in a star formation efficiency of 50%. The mass involved in star formation depends on the gas fraction that dissipates sufficient kinetic energy in shocks. Thus, clouds with larger turbulent motions will result in lower star formation efficiencies. This implies that globally unbound, and therefore transient giant molecular clouds (GMCs), can account for the low efficiency of star formation observed in our Galaxy without recourse to magnetic fields or feedback processes. Observations of the dynamic stability in molecular regions suggest that GMCs may not be self-gravitating, supporting the ideas presented in this letter.Comment: 5 pages, 3 figures, accepted for MNRAS as a lette

    Westerlund 1 as a Template for Massive Star Evolution

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    With a dynamical mass M_dyn ~ 1.3x10e5 M_sun and a lower limit M_cl>5x10e4 M_sun from star counts, Westerlund 1 is the most massive young open cluster known in the Galaxy and thus the perfect laboratory to study massive star evolution. We have developed a comprehensive spectral classification scheme for supergiants based on features in the 6000-9000A range, which allows us to identify >30 very luminous supergiants in Westerlund 1 and ~100 other less evolved massive stars, which join the large population of Wolf-Rayet stars already known. Though detailed studies of these stars are still pending, preliminary rough estimates suggest that the stars we see are evolving to the red part of the HR diagram at approximately constant luminosity.Comment: To be published in Proceedings of IAU Symposium 250: Massive Stars as Cosmic Engines, held in Kaua'i (Hawaii, USA), Dec 2007, edited by F. Bresolin, P.A. Crowther & J. Puls (Cambridge University Press

    Broadening the Mission: Research Activity among University Labor Education/Labor Studies Professionals

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    [Excerpt] This study examines research activity among university and college labor education/labor studies professionals. Using data gathered in a survey of faculty employed in the field, the paper presents information concerning the extent and focus of these research activities, the methodologies employed, the outlets for the research products that result, and the factors limiting such work. The findings of this study indicate that research, of both an applied and scholarly nature, is an increasingly significant part of the work of labor education/labor studies professionals. The study concludes with a discussion of the implications this trend has for the labor education/labor studies field, with special attention being given to the role research activity can play in meeting the needs of unions, union members, and union leaders

    On column density thresholds and the star formation rate

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    We present the results of a numerical study designed to address the question of whether there is a column density threshold for star formation within molecular clouds. We have simulated a large number of different clouds, with volume and column densities spanning a wide range of different values, using a state-of-the-art model for the coupled chemical, thermal and dynamical evolution of the gas. We show that star formation is only possible in regions where the mean (area-averaged) column density exceeds 1021 cm−210^{21} \: {\rm cm^{-2}}. Within the clouds, we also show that there is a good correlation between the mass of gas above a K-band extinction AK=0.8A_{\rm K} = 0.8 and the star formation rate (SFR), in agreement with recent observational work. Previously, this relationship has been explained in terms of a correlation between the SFR and the mass in dense gas. However, we find that this correlation is weaker and more time-dependent than that between the SFR and the column density. In support of previous studies, we argue that dust shielding is the key process: the true correlation is one between the SFR and the mass in cold, well-shielded gas, and the latter correlates better with the column density than the volume density.Comment: 21 pages and 12 figures. Accepted for publication in MNRA
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