24,023 research outputs found

    R-matrix Floquet theory for laser-assisted electron-atom scattering

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    A new version of the R-matrix Floquet theory for laser-assisted electron-atom scattering is presented. The theory is non-perturbative and applicable to a non-relativistic many-electron atom or ion in a homogeneous linearly polarized field. It is based on the use of channel functions built from field-dressed target states, which greatly simplifies the general formalism.Comment: 18 pages, LaTeX2e, submitted to J.Phys.

    Improved initial data for black hole binaries by asymptotic matching of post-Newtonian and perturbed black hole solutions

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    We construct approximate initial data for non-spinning black hole binary systems by asymptotically matching the 4-metrics of two tidally perturbed Schwarzschild solutions in isotropic coordinates to a resummed post-Newtonian 4-metric in ADMTT coordinates. The specific matching procedure used here closely follows the calculation in gr-qc/0503011, and is performed in the so called buffer zone where both the post-Newtonian and the perturbed Schwarzschild approximations hold. The result is that both metrics agree in the buffer zone, up to the errors in the approximations. However, since isotropic coordinates are very similar to ADMTT coordinates, matching yields better results than in the previous calculation, where harmonic coordinates were used for the post-Newtonian 4-metric. In particular, not only does matching improve in the buffer zone, but due to the similarity between ADMTT and isotropic coordinates the two metrics are also close to each other near the black hole horizons. With the help of a transition function we also obtain a global smooth 4-metric which has errors on the order of the error introduced by the more accurate of the two approximations we match. This global smoothed out 4-metric is obtained in ADMTT coordinates which are not horizon penetrating. In addition, we construct a further coordinate transformation that takes the 4-metric from global ADMTT coordinates to new coordinates which are similar to Kerr-Schild coordinates near each black hole, but which remain ADMTT further away from the black holes. These new coordinates are horizon penetrating and lead, for example, to a lapse which is everywhere positive on the t=0 slice. Such coordinates may be more useful in numerical simulations.Comment: 25 pages, 21 figures. Replaced with accepted versio

    Music Collections in American Public Libraries

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    This article presents a broad survey of music collections in public libraries in the United States. Characteristics common to the majority of American public libraries are discussed, including origin, funding, and mission as an educational institution. Using a 1949 survey compiled by Otto Luening, Music Materials and the Public Library, as a basis for comparison, the authors surveyed seven libraries representing one or more of the following communities: small towns, school districts with nationally recognized music education programs, large cities, and locations associated recognizably American musical styles (e.g., New Orleans and jazz). The results this informal web survey demonstrate that certain features of American public library music collections have remained essentially the same since the time of Luening\u27s survey. Recordings still make up the majority of music collections, particularly in smaller cities, and there is still a lack of money to acquire materials and a shortage of qualified personnel to administer the collections. The decrease in arts education in American public schools has much to do with what public libraries are collecting with regard to music. There have been movements in the United States to increase awareness of the importance of music education, but none of these national groups has made formal connections to public libraries, nor have they addressed the important role that public libraries could play in this effort

    Utility of Pelvic Computed Tomography Angiography Prior to Prostatic Artery Embolization

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    Pelvic computed tomography angiography (CTA) prior to prostatic artery embolization is a beneficial tool for preprocedural planning to increase the likelihood of success during what can be a challenging procedure. Additionally, the same CTA images can be used for calculating the baseline prostate volume as well as for intraprocedural anatomic guidance, adding to the value of the scan. This article discusses the technique used for pelvic CTA and its role in preprocedural assessment of the pelvic vasculature prior to prostatic artery embolization

    Nutrition Strategies for Triathlon

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    Contemporary sports nutrition guidelines recommend that each athlete develop a personalised, periodised and practical approach to eating that allows him or her to train hard, recover and adapt optimally, stay free of illness and injury and compete at their best at peak races. Competitive triathletes undertake a heavy training programme to prepare for three different sports while undertaking races varying in duration from 20 min to 10 h. The everyday diet should be adequate in energy availability, provide CHO in varying amounts and timing around workouts according to the benefits of training with low or high CHO availability and spread high-quality protein over the day to maximise the adaptive response to each session. Race nutrition requires a targeted and well-practised plan that maintains fuel and hydration goals over the duration of the specific event, according to the opportunities provided by the race and other challenges, such as a hot environment. Supplements and sports foods can make a small contribution to a sports nutrition plan, when medical supplements are used under supervision to prevent/treat nutrient deficiencies (e.g. iron or vitamin D) or when sports foods provide a convenient source of nutrients when it is impractical to eat whole foods. Finally, a few evidence-based performance supplements may contribute to optimal race performance when used according to best practice protocols to suit the triathlete’s goals and individual responsiveness

    The Epidemic Curve: II

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    A demand-driven approach for a multi-agent system in Supply Chain Management

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    This paper presents the architecture of a multi-agent decision support system for Supply Chain Management (SCM) which has been designed to compete in the TAC SCM game. The behaviour of the system is demand-driven and the agents plan, predict, and react dynamically to changes in the market. The main strength of the system lies in the ability of the Demand agent to predict customer winning bid prices - the highest prices the agent can offer customers and still obtain their orders. This paper investigates the effect of the ability to predict customer order prices on the overall performance of the system. Four strategies are proposed and compared for predicting such prices. The experimental results reveal which strategies are better and show that there is a correlation between the accuracy of the models' predictions and the overall system performance: the more accurate the prediction of customer order prices, the higher the profit. © 2010 Springer-Verlag Berlin Heidelberg
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