31,779 research outputs found

    XMM-Newton observations of EF Eridani: the textbook example of low-accretion rate polars

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    Archival X-ray observations of EF Eridani obtained in a low state revealed distinct X-ray detections at a luminosity L_X ~ 2 10^{29} erg/s, three orders of magnitude below its high state value. The plasma temperature was found to be as low as kT \loa 2 keV, a factor 10 below the high state. The X-ray/UV/IR spectral energy distribution suggests faint residual accretion rather than coronal emission as being responsible for the low-state X-ray emission. EF Eri thus showed a clear transition from being shock-dominated in the high state to be cyclotron-dominated in the low state. From the optical/UV spectral energy distribution we re-determine the photospheric temperature of the white dwarf to \~10000K. Contrary to earlier claims, WD model atmospheres produce sufficient UV flux to reproduce the published GALEX flux and orbital modulation.Comment: A&A, in pres

    Direct and Intermediated Marketing of Local Foods in the United States

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    This study uses nationally representative data on the marketing of local foods to assess the relative scale of local food marketing channels. This research documents that sales through intermediated marketing channels, such as farmers’ sales to local grocers and restaurants, account for a large portion of all local food sales. Small and medium-sized farms dominate local foods sales marketed exclusively through direct-to-consumer channels (foods sold at roadside stands or farmers’ markets, for example) while large farms dominate local food sales marketed exclusively through intermediated channels. Farmers marketing food locally are most prominent in the Northeast and the West Coast regions and areas close to densely populated urban markets. Climate and topography favoring the production of fruits and vegetables, proximity to and neighboring farm participation in farmers’ markets, and good transportation and information access are found to be associated with higher levels of direct-to-consumer sales.Local foods, direct marketing channels, direct sales, intermediated sales Acknowledgments: The, Agricultural and Food Policy, Marketing,

    Experimental determination of a nonclassical Glauber-Sudarshan P function

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    A quantum state is nonclassical if its Glauber-Sudarshan P function fails to be interpreted as a probability density. This quantity is often highly singular, so that its reconstruction is a demanding task. Here we present the experimental determination of a well-behaved P function showing negativities for a single-photon-added thermal state. This is a direct visualization of the original definition of nonclassicality. The method can be useful under conditions for which many other signatures of nonclassicality would not persist.Comment: 4 pages, 4 figure

    Radiative corrections in neutrino-deuterium disintegration

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    The radiative corrections of order alpha for the charged- and neutral-current neutrino-deuterium disintegration for energies relevant to the SNO experiment are evaluated. Particular attention is paid to the issue of the bremsstrahlung detection threshold. It is shown that the radiative corrections to the total cross section for the charged current reaction are independent of that threshold, as they must be for consistency, and amount to a slowly decreasing function of the neutrino energy E-nu, varying from about 4% at low energies to 3% at the end of the B-8 spectrum. The differential cross section corrections, on the other hand, do depend on the bremsstrahlung detection threshold. Various choices of the threshold are discussed. It is shown that for a realistic choice of the threshold and for the actual electron energy threshold of the SNO detector, the deduced B-8 nu(e) flux should be decreased by about 2%. The radiative corrections to the neutral-current reaction are also evaluated

    Theism and Psychological Science: A Call for Rapprochement

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    The authors offer two arguments for the inclusion of theism in natural science. First, an argument against excluding theism is offered. Though early roots of science promoted a view that it is a way to accumulate knowledge that is untainted by presuppositions and traditions, postmodern critiques call this into question. Scientists have sometimes rejected religion as a context-dependent, tradition-based way of knowing, yet science itself is also context-dependent and tradition-based. Second, an argument for including theism in psychological is offered. Theistic beliefs are relevant insofar as they are part of human experience for many, they represent a form of human diversity, and they have been associated with some positive health outcomes
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