14,147 research outputs found

    Proposed New Test of Spin Effects in General Relativity

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    The recent discovery of a double-pulsar PSR J0737-3039A/B provides an opportunity of unequivocally observing, for the first time, spin effects in general relativity. Existing efforts involve detection of the precession of the spinning body itself. However, for a close binary system, spin effects on the orbit may also be discernable. Not only do they add to the advance of the periastron (by an amount which is small compared to the conventional contribution) but they also give rise to a precession of the orbit about the spin direction. The measurement of such an effect would also give information on the moment of inertia of pulsars

    Fluctuations and Noise: A General Model with Applications

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    A wide variety of dissipative and fluctuation problems involving a quantum system in a heat bath can be described by the independent-oscillator (IO) model Hamiltonian. Using Heisenberg equations of motion, this leads to a generalized quantum Langevin equation (QLE) for the quantum system involving two quantities which encapsulate the properties of the heat bath. Applications include: atomic energy shifts in a blackbody radiation heat bath; solution of the problem of runaway solutions in QED; electrical circuits (resistively shunted Josephson barrier, microscopic tunnel junction, etc.); conductivity calculations (since the QLE gives a natural separation between dissipative and fluctuation forces); dissipative quantum tunneling; noise effects in gravitational wave detectors; anomalous diffusion; strongly driven quantum systems; decoherence phenomena; analysis of Unruh radiation and entropy for a dissipative system.Comment: Presented at the SPIE International Symposium on Fluctuations and Noise in Photonics and Quantum Optics (Austin, May 2005

    The Ultraviolet Morphology of Galaxies

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    The vacuum ultraviolet offers a unique perspective on galaxy morphology, stellar populations, and interstellar material which is of particular relevance to interpreting high redshift galaxies and the history of cosmic star formation. Here we review UV imaging studies of galaxies since 1990.Comment: 10 pages; tar.gz file includes LaTeX text file, 6 low-resolution PostScript figures, and 3 style files. For *.ps.gz file with full res figures, see http://www.astro.virginia.edu/~rwo/ Paper to be published in "The Ultraviolet Universe at Low and High Redshift" ed. W. H. Waller (AIP Press) 199

    Two oscillators in a common heat bath

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    We show that the case of two oscillators in a common heat bath cannot be reduced to an effective one body problem. In addition, there is an interaction between the oscillators, even at zero temperature, due to the fluctuations caused in both oscillators by the zero-point oscillations of the electromagnetic field

    Finding the balance in complex regional pain syndrome. Expertise, optimism, and evidence

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    Complex regional pain syndrome (CRPS), perhaps more than any other chronic pain disorder, is perplexing. It is highly disabling, particularly once it has “set in,” and it has a tendency to polarize the community—some view it as a quasidiagnosis to obscure malingering or conceal substandard clinical skills,1 and others as a multiple system overprotective response.2 What is agreed is that its pathophysiology is not completely understood and that it is difficult to treat. In light of this rather murky backdrop, we welcome the new perspectives article in this issue of Neurology® by Birklein et al.3 They describe their own clinical approach to the problem and their impressions of what works, what does not, and where the field might be heading. The lead author is the most prolific and arguably the most important researcher in this field, and the article clearly draws on a wealth of expertise and clinical experience probably unmatched globally. The article reminds us of the remaining substantial challenges that we face: for example, the need for prospective studies, higher quality clinical trials and audits, and a putative model that accounts for the transition from acute CRPS to chronic CRPS, which is arguably characterized by distinct pathophysiology. Anyone who treats a good number of CRPS patients will recognize the clinical patterns to which the authors allude and be comforted by the realization that even this group, at the top of the field, share the same substantial treatment challenges.G.L.M. is supported by a Principal Research Fellowship from the National Health & Medical Research Council of Australia ID 1061279

    Economic Evaluation of Phase Farming with Lucerne on the Esperance Sandplain

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    This study examines the profitability of phase farming with lucerne for a farming system on the South Coast of Western Australia. Consistent with previous studies, lucerne appears promising within niches in the farming system. However, further improvements in the production and / or utilisation of lucerne are likely to be required before widespread adoption is financially attractive. Several important conclusions emerge from this study: The profitability of lucerne is primarily due to savings on supplementary feed costs over summer and autumn. While lucerne does provide benefits to following crops, the net impact of lucerne on the profitability of a farmer's cropping programme is likely to be negligible. The profitability and optimal area of lucerne is likely to be significantly higher on farms where prime lamb production occurs. This will especially be the case where lambs are sold as carryover stock in mid-late summer. The economic value of lucerne diminishes as a larger area is established. The implication of this is that just because some lucerne is good, more may not necessarily be better. Lucerne appears able to provide some reduction in recharge without a loss in profit. However, for the farming district examined in this study, the dominance of high recharge soil groups creates particular challenges. Significant improvements in lucerne production and / or utilisation will be required before it will compete with current land uses on some of the major soil groups.Farm Management,
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