19,799 research outputs found

    The Mariner Jupiter/Saturn IRIS experiment

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    After a schematic representation of the IRIS experiment, objectives of the program are outlined. Specifically data cover: (1) determination of energy balance for Jupiter and Saturn, (2) determination of methane, ammonia, hydrogen and water vapor quantities, (3) three dimensional temperature fields, (4) hydrogen-helium ratios and isotopic ratios of H/C, C/N, and C/O

    Excitations in time-dependent density-functional theory

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    An approximate solution to the time-dependent density functional theory (TDDFT) response equations for finite systems is developed, yielding corrections to the single-pole approximation. These explain why allowed Kohn-Sham transition frequencies and oscillator strengths are usually good approximations to the true values, and why sometimes they are not. The approximation yields simple expressions for G\"orling-Levy perturbation theory results, and a method for estimating expectation values of the unknown exchange-correlation kernel.Comment: 4 pages, 1 tabl

    Ejaculate allocation by male sand martins, Riparia riparia

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    Males of many species allocate sperm to ejaculates strategically in response to variation in the risk and intensity of sperm competition. The notable exception is passerine birds, in which evidence for strategic allocation is absent. Here we report the results of a study testing for strategic ejaculate allocation in a passerine bird, the sand martin (Riparia riparia). Natural ejaculates were collected from males copulating with a model female. Ejaculates transferred in the presence of a rival male contained significantly more sperm than ejaculates transferred in the absence of a rival male. There was no evidence that this difference was due to the confounding effects of the year of ejaculate collection, the identity of the model female, the colony, the stage of season or the period of the day in which ejaculates were collected. A more detailed examination of the ejaculate patterns of individual males, achieved by the DNA profiling of ejaculates, provided additional evidence for strategic allocation of sperm

    On the density-potential mapping in time-dependent density functional theory

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    The key questions of uniqueness and existence in time-dependent density functional theory are usually formulated only for potentials and densities that are analytic in time. Simple examples, standard in quantum mechanics, lead however to non-analyticities. We reformulate these questions in terms of a non-linear Schr\"odinger equation with a potential that depends non-locally on the wavefunction.Comment: 8 pages, 2 figure

    Joint Comprehensive Plan of Action Opportunity for HIF in Iran

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    Cooperation in fusion energy research and high-energy accelerators has been a “bridge over troubled waters” for most of a century. Physics research has traditionally been an international endeavor, involving the earliest accelerator developments, and hitting a hiatus only during World War II. Fusion energy research using magnetic confinement was internationalized by the Geneva meeting in 1958. Iran is and has been a participant in fusion research, even during the troubles of the past couple decades..

    Time-dependent density functional theory: Past, present, and future

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    Time-dependent density functional theory (TDDFT) is presently enjoying enormous popularity in quantum chemistry, as a useful tool for extracting electronic excited state energies. This article discusses how TDDFT is much broader in scope, and yields predictions for many more properties. We discuss some of the challenges involved in making accurate predictions for these properties.Comment: 12 pages, 4 figure

    Readiness of HIF Using the Single Pass RF Driver

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    Readiness for a concerted push to power production was the underlying theme from the inaugural HIF Workshop in 1976 through the review of ICF programs by DOE’s Energy Research and Advisory Board in 1979. Using John Lawson’s 1987 paper “Whither Heavy Ion Fusion?” [1] as a foil, this paper discusses the continuing vitality of the argument for HIF’s readiness against the backdrop that this vision is not in evidence today, having been occluded by political policies causing diversion of the HIF community into peripheral science that, although excellent, is in fact not required to complete the development of a HIF energy source..

    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

    Joint Comprehensive Plan of Action Opportunity for HIF in Iran

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    Cooperation in fusion energy research and high-energy accelerators has been a “bridge over troubled waters” for most of a century. Physics research has traditionally been an international endeavor, involving the earliest accelerator developments, and hitting a hiatus only during World War II. Fusion energy research using magnetic confinement was internationalized by the Geneva meeting in 1958. Iran is and has been a participant in fusion research, even during the troubles of the past couple decades..

    Enhanced dielectrophoresis of nanocolloids by dimer formation

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    We investigate the dielectrophoretic motion of charge-neutral, polarizable nanocolloids through molecular dynamics simulations. Comparison to analytical results derived for continuum systems shows that the discrete charge distributions on the nanocolloids have a significant impact on their coupling to the external field. Aggregation of nanocolloids leads to enhanced dielectrophoretic transport, provided that increase in the dipole moment upon aggregation can overcome the related increase in friction. The dimer orientation and the exact structure of the nanocolloid charge distribution are shown to be important in the enhanced transport
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