114 research outputs found

    Application of the method of tight binding to the electronic structure of solids /

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    Population Characteristics, Morphometry, and Growth of Harvested Gray Wolves and Coyotes in Alaska

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    Few concurrent studies exist of sympatric gray wolf (Canis lupus) and coyote (C. latrans) harvest at far northern latitudes. Moreover, no studies explicitly examine effects of concurrent harvest on phenotypes of wolves and coyotes. We documented changes in sex and age characteristics and morphology of gray wolves and coyotes harvested by hunters near Ptarmigan Lake, east-central Alaska, USA, between 1998 and 2001. We hypothesized that the harvest would result in larger, heavier canids, reduce densities, and increase young to adult ratios in both wolves and coyotes. We generated von Bertalanffy growth curves indicating that wolves and coyotes of both sexes increased in length or weight until 2 or 3 years old. No significant changes in either mean length or weight or length to weight ratios occurred during the 3-year study, except that coyote mean length was longer over the last winter of study. Catch-per-unit effort (CPUE) for wolves ranged from 0.061 to 0.112 killed/day and for coyotes from 0.552 to 0.11 killed/day over the study. CPUE indicated that coyotes but not wolves declined in abundance. Changes in male to female and young to adult ratios did not differ significantly for either canid. We posit that coyote populations were disproportionately affected by the conflation of the severe Arctic environment and sustained harvest. Our findings will be beneficial for managing sympatric canid populations and for understanding demographic responses to density-dependent processes in wolves and coyotes, especially at far northern latitudes.Il existe peu d’études concomitantes sur la rĂ©colte du loup gris (Canis lupus) et du coyote (C. latrans) sympatriques dans les hautes latitudes nordiques. Par ailleurs, aucune Ă©tude n’examine explicitement les effets de la rĂ©colte concomitante sur les phĂ©notypes des loups et des coyotes. Nous avons documentĂ© les changements sur le plan de la morphologie et des caractĂ©ristiques du sexe et de l’ñge des loups gris et des coyotes rĂ©coltĂ©s par les chasseurs Ă  proximitĂ© du lac Ptarmigan, dans le centre-est de l’Alaska, aux États-Unis, de 1998 Ă  2001. Nous avons formulĂ© l’hypothĂšse voulant que la rĂ©colte donnerait lieu Ă  des canidĂ©s plus gros et plus lourds, rĂ©duirait les densitĂ©s et augmenterait les rapports entre jeunes et adultes, tant chez les loups que chez les coyotes. Nous avons produit des courbes de croissance de von Bertalanffy selon lesquelles la longueur ou le poids des loups et des coyotes des deux sexes augmentait jusqu’à l’ñge de deux ou trois ans. Sur le plan de la longueur ou du poids moyen, ou des rapports moyens entre la longueur et le poids, aucun changement important n’a Ă©tĂ© enregistrĂ© pendant l’étude de trois ans, sauf que la longueur moyenne du coyote Ă©tait plus grande au cours du dernier hiver de l’étude. Pour le loup, la capture par unitĂ© d’effort (CPUE) variait de 0,061 Ă  0,112 bĂȘte tuĂ©e/jour, tandis que pour le coyote, elle variait de 0,552 Ă  0,11 bĂȘte tuĂ©e/jour dans le courant de l’étude. Selon la CPUE, l’abondance des coyotes a chutĂ©, mais pas celle des loups. Pour l’un ou l’autre des canidĂ©s, les variations en matiĂšre de rapports entre les mĂąles et les femelles, et entre les jeunes et les adultes n’étaient pas considĂ©rables. Nous postulons que les populations de coyotes ont Ă©tĂ© touchĂ©es de maniĂšre disproportionnĂ©e Ă  la fois par l’environnement arctique rigoureux et par une rĂ©colte soutenue. Nos constatations joueront un rĂŽle dans la gestion des populations de canidĂ©s sympatriques et dans la comprĂ©hension des rĂ©ponses dĂ©mographiques aux processus dĂ©pendant de la densitĂ© chez les loups et les coyotes, surtout dans les hautes latitudes nordiques

    Collaborative care for depression and anxiety problems

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    This review is published as a Cochrane Review in the Cochrane Database of Systematic Reviews 2012, Issue 10. Cochrane Reviews are regularly updated as new evidence emerges and in response to comments and criticisms, and the Cochrane Database of Systematic Reviews should be consulted for the most recent version of the Review.Common mental health problems, such as depression and anxiety, are estimated to affect up to 15% of the UK population at any one time, and health care systems worldwide need to implement interventions to reduce the impact and burden of these conditions. Collaborative care is a complex intervention based on chronic disease management models that may be effective in the management of these common mental health problems

    The James Webb Space Telescope Mission

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    Twenty-six years ago a small committee report, building on earlier studies, expounded a compelling and poetic vision for the future of astronomy, calling for an infrared-optimized space telescope with an aperture of at least 4m4m. With the support of their governments in the US, Europe, and Canada, 20,000 people realized that vision as the 6.5m6.5m James Webb Space Telescope. A generation of astronomers will celebrate their accomplishments for the life of the mission, potentially as long as 20 years, and beyond. This report and the scientific discoveries that follow are extended thank-you notes to the 20,000 team members. The telescope is working perfectly, with much better image quality than expected. In this and accompanying papers, we give a brief history, describe the observatory, outline its objectives and current observing program, and discuss the inventions and people who made it possible. We cite detailed reports on the design and the measured performance on orbit.Comment: Accepted by PASP for the special issue on The James Webb Space Telescope Overview, 29 pages, 4 figure

    The sociotechnical dynamics of a travel management reengineering project

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    This thesis examines the travel management reengineering project of one DoD command. It analyzes the process selection, redesign, and implementation of the travel project and discusses the managerial implications of the project's dynamics. A review of process innovation, reengineering, and planned-change literature provides a framework for exploring the activities of the reengineering team, but semi-structured interviews and personal observations of project participants are the major sources of data for the analysis. The analysis is completed with a comprehensive look at lessons learned from the project. The research concludes that the travel management project required senior management participation and guidance, the active involvement of all project team members, and an appreciation for the natural reactions of the intended users of the new process.http://archive.org/details/thesociotechnica1094532223NAU.S. Navy (U.S.N.) authorsApproved for public release; distribution is unlimited

    Efficient Calculation of Electron States in Self-Assembled Quantum Dots: Application to Auger Relaxation

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    An efficient method for calculation of self-assembled dot states within the effective mass approximation is described and its application to the calculation of Auger relaxation rates is detailed. The method is based on expansion of the dot states in a harmonic oscillator basis whose parameters are optimised to improve the convergence rate. This results in at least an order of magnitude reduction in the number of basis states required to represent electron states accurately compared to the conventional plane wave approach. Auger relaxation rates are calculated for harmonic oscillator model states and exact states for various pyramidal models. The dipole approximation, previously used to calculate Auger rates, is found to be inaccurate by a factor of around 2–3. The harmonic oscillator states do not reproduce the rates for the more realistic pyramidal models very well and even within the set of pyramidal models variations in the dot shape and size can change the rates by up to an order of magnitude. Typical Auger relaxation rates are on a picosecond timescale but the actual value is strongly dependent on the density of electrons outside the dot
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