16,063 research outputs found

    Approximate trajectory data for missions to the major planets

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    Contour charts and tables on trajectory data for missions to Jupiter, Saturn, Uranus, and Neptune and their moon

    Scales for co-compact embeddings of virtually free groups

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    Let Γ\Gamma be a group which is virtually free of rank at least 2 and let Ftd(Γ)\mathcal{F}_{td}(\Gamma) be the family of totally disconnected, locally compact groups containing Γ\Gamma as a co-compact lattice. We prove that the values of the scale function with respect to groups in Ftd(Γ)\mathcal{F}_{td}(\Gamma) evaluated on the subset Γ\Gamma have only finitely many prime divisors. This can be thought of as a uniform property of the family Ftd(Γ)\mathcal{F}_{td}(\Gamma).Comment: 12 pages; key words: uniform lattice, virtually free group, totally disconnected group, scale function (Error in references corrected in version 2

    A dc to dc converter

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    The object of the invention is to provide an improved converter for converting one direct current voltage to another. A plurality of phased square wave voltages are provided from a ring counter through amplifiers to a like plurality of output transformers. Each of these transformers has two windings, and S(1) winding and an S(2) winding. The S(1) windings are connected in series, then the S(2) windings are connected in series, and finally, the two sets of windings are connected in series. One of six SCRs is connected between each two series connected windings to a positive output terminal and one of diodes is connected between each set of two windings of a zero output terminal. By virtue of this configuration, a quite high average direct current voltage is obtained, which varies between full voltage and two-thirds full voltage rather than from full voltage to zero. Further, its variation, ripple frequency, is reduced to one-sixth of that present in a single phase system. Application to raising battery voltage for an ion propulsion system is mentioned

    Static inverters which sum a plurality of waves Patent

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    Describing static inverter with single or multiple phase outpu

    Correlated photon pairs generated from a warm atomic ensemble

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    We present measurements of the cross-correlation function of photon pairs at 780 nm and 1367 nm, generated in a hot rubidium vapor cell. The temporal character of the biphoton is determined by the dispersive properties of the medium where the pair generation takes place. We show that short correlation times occur for optically thick samples, which can be understood in terms of off-resonant pair generation. By modifying the linear response of the sample, we produce near-resonant photon pairs, which could in principle be used for entanglement distribution

    Winter wheat: A model for the simulation of growth and yield in winter wheat

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    The basic ideas and constructs for a general physical/physiological process level winter wheat simulation model are documented. It is a materials balance model which calculates daily increments of photosynthate production and respiratory losses in the crop canopy. The partitioning of the resulting dry matter to the active growing tissues in the plant each day, transpiration and the uptake of nitrogen from the soil profile are simulated. It incorporates the RHIZOS model which simulates, in two dimensions, the movement of water, roots, and soluble nutrients through the soil profile. It records the time of initiation of each of the plant organs. These phenological events are calculated from temperature functions with delays resulting from physiological stress. Stress is defined mathematically as an imbalance in the metabolite supply; demand ratio. Physiological stress is also the basis for the calculation of rates of tiller and floret abortion. Thus, tillering and head differentiation are modeled as the resulants of the two processes, morphogenesis and abortion, which may be occurring simulaneously

    From 'digital' to 'smart': upgrading the city

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    In this paper we seek to reflect on the way in which 'digital cities' later re-emerge as 'smart cities' (both in terms of the approaches and also the actual cities) and what lessons can be learned about the role of ICTs in how they shape urban space. We will focus on looking at how the lack of understanding of the city as a 'place' is often a common factor in the lack of longevity in 'digital city' initiatives and discuss the corresponding implications for the emergence of 'smart cities'. We draw on a study of the city of Bristol, UK in order to look at the variety of initiatives that took Bristol from a 1990's digital city to the current 'smart' projects. We conclude by reflecting on what can be learnt from the lessons of the failed Digital City projects of 1990's and discuss the role that placemaking could play in the development of socially and spatially sustainable smart cities

    Electron spin relaxation in organic semiconductors probed through muSR

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    Muon spin spectroscopy and in particular the avoided level crossing technique is introduced, with the aim of showing it as a very sensitive local probe for electron spin relaxation in organic semiconductors. Avoided level crossing data on TMS-pentacene at different temperatures are presented, and they are analysed to extract the electron spin relaxation rate, that is shown to increase on increasing the temperature from 0.02 MHz to 0.33 MHz at 3 K and 300 K respectively.Comment: International Conference TSN2010 "Trends in spintronics and nanomagnetism

    Hospital Community Benefits After the ACA: Building on State Experience

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    Analyzes hospitals' requirements to conduct community health needs assessments, financial assistance and billing and collection policies, and community benefit reporting and oversight strategies. Notes implications for federal and state law and practice

    Hospital Community Benefits After the ACA: The Emerging Federal Framework

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    Outlines the federal framework on requirements for hospitals to provide community benefit activities in exchange for tax-exempt status under the 2010 healthcare reform, including community health needs assessments; state policy options; and challenges
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