7,108 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

    The star formation efficiency and its relation to variations in the initial mass function

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    We investigate how the dynamical state of a turbulently supported, 1000 solar mass, molecular cloud affects the properties of the cluster it forms, focusing our discussion on the star formation efficiency (SFE) and the initial mass function (IMF). A variety of initial energy states are examined in this paper, ranging from clouds with PE = 0.1 KE to clouds with PE = 10 KE, and for both isothermal and piece-wise polytropic equations of state (similar to that suggested by Larson). It is found that arbitrary star formation efficiencies are possible, with strongly unbound clouds yielding very low star formation efficiencies. We suggest that the low star formation efficiency in the Maddelena cloud may be a consequence of the relatively unbound state of its internal structure. It is also found that competitive accretion results in the observed IMF when the clouds have initial energy states of PE >= KE. We show that under such conditions the shape of the IMF is independent of time in the calculations. This demonstrates that the global accretion process can be terminated at any stage in the cluster's evolution, while still yielding a distribution of stellar masses that is consistent with the observed IMF. As the clouds become progressively more unbound, competitive accretion is less important and the protostellar mass function flattens. These results predict that molecular clouds should be permeated with a distributed population of stars that follow a flatter than Salpeter IMF.Comment: 8 pages, 6 figures, accepted by MNRAS for publictaion. Now available through the 'Online Early' schem

    Clump Lifetimes and the Initial Mass Function

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    Recent studies of dense clumps/cores in a number of regions of low-mass star formation have shown that the mass distribution of these clumps closely resembles the initial mass function (IMF) of field stars. One possible interpretation of these observations is that we are witnessing the fragmentation of the clouds into the IMF, and the observed clumps are bound pre-stellar cores. In this paper, we highlight a potential difficulty in this interpretation, namely that clumps of varying mass are likely to have systematically varying lifetimes. This timescale problem can effectively destroy the similarity bewteen the clump and stellar mass functions, such that a stellar-like clump mass function (CMF) results in a much steeper stellar IMF. We also discuss some ways in which this problem may be avoided.Comment: 7 pages, 3 figures, accepted to MNRA

    Income and happiness: Evidence, explanations and economic implications

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    There is now a great deal of micro-econometric evidence, both cross-section and panel, showing that income is positively correlated with well-being. Yet the famous Easterlin paradox shows essentially no change in average happiness at the country level, despite spectacular rises in per capita GDP. We argue that survey well-being questions are indeed good proxy measures of utility, and resolve the Easterlin paradox by appealing to income comparisons: these can be to others (social comparisons) or to oneself in the past (habituation). We review a substantial amount of econometric, experimental and neurological literature consistent with comparisons, and then spell out the implications for a wide range of economic issues.income ; happiness ; social comparisons ; habituation ; economic policy

    Do Warrantless Breathalyzer Tests Violate the Fourth Amendment

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    The Movement for Home Rule in Prince Georges County, Maryland 1961-1964

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    The purpose of this paper has been to trace the movement for constitutional home rule in Prince Georges County, Maryland. Special attention has been given to the effects of the movement on Prince Georges County government. As a conclusion to this study, several more recommendations are suggested as improvements on the local government administration

    Web-Based Digital Portfolios and Counselor Supervision

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    Web-based digital portfolios provide a promising tool for counselor supervisors looking for effective ways to evaluate counselor candidates while maximizing the associated learning process. This paper describes a project involving the use of web-based portfolios that were created by counselor candidates. The project illustrates the benefits of the web-based portfolio for both the counselor supervisor and for the counselors in training
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