25,334 research outputs found

    New Measurements of the Radio Photosphere of Mira based on Data from the JVLA and ALMA

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    We present new measurements of the millimeter wavelength continuum emission from the long period variable Mira (oo Ceti) at frequencies of 46 GHz, 96 GHz, and 229 GHz (λ\lambda~7 mm, 3 mm, and 1 mm) based on observations obtained with the Jansky Very Large Array (JVLA) and the Atacama Large Millimeter/submillimeter Array (ALMA). The measured millimeter flux densities are consistent with a radio photosphere model derived from previous observations, where flux density, Sνν1.86S_{\nu}\propto\nu^{1.86}. The stellar disk is resolved, and the measurements indicate a decrease in the size of the radio photosphere at higher frequencies, as expected if the opacity decreases at shorter wavelengths. The shape of the radio photosphere is found to be slightly elongated, with a flattening of ~10-20%. The data also reveal evidence for brightness non-uniformities on the surface of Mira at radio wavelengths. Mira's hot companion, Mira B was detected at all three observed wavelengths, and we measure a radius for its radio-emitting surface of 2.0×1013\approx2.0\times10^{13} cm. The data presented here highlight the power of the JVLA and ALMA for the study of the atmospheres of evolved stars.Comment: Accepted to ApJ; 27 pages, 7 figure

    Comparison of analgesic effects and patient tolerability of nabilone and dihydrocodeine for chronic neuropathic pain: randomised, crossover, double blind study

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    <b>Objective</b>: To compare the analgesic efficacy and side effects of the synthetic cannabinoid nabilone with those of the weak opioid dihydrocodeine for chronic neuropathic pain. <b>Design</b>: Randomised, double blind, crossover trial of 14 weeks’ duration comparing dihydrocodeine and nabilone. <b>Setting</b>: Outpatient units of three hospitals in the United Kingdom. <b>Participants</b>: 96 patients with chronic neuropathic pain, aged 23-84 years. <b>Main outcome measures</b>: The primary outcome was difference between nabilone and dihydrocodeine in pain, as measured by the mean visual analogue score computed over the last 2 weeks of each treatment period. Secondary outcomes were changes in mood, quality of life, sleep, and psychometric function. Side effects were measured by a questionnaire. <b>Intervention</b>: Patients received a maximum daily dose of 240 mg dihydrocodeine or 2 mg nabilone at the end of each escalating treatment period of 6 weeks. Treatment periods were separated by a 2 week washout period. <b>Results</b>: Mean baseline visual analogue score was 69.6 mm (range 29.4-95.2) on a 0-100 mm scale. 73 patients were included in the available case analysis and 64 patients in the per protocol analysis. The mean score was 6.0 mm longer for nabilone than for dihydrocodeine (95% confidence interval 1.4 to 10.5) in the available case analysis and 5.6 mm (10.3 to 0.8) in the per protocol analysis. Side effects were more frequent with nabilone. <b>Conclusion</b>: Dihydrocodeine provided better pain relief than the synthetic cannabinoid nabilone and had slightly fewer side effects, although no major adverse events occurred for either drug

    Experimental verification of reciprocity relations in quantum thermoelectric transport

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    Symmetry relations are manifestations of fundamental principles and constitute cornerstones of modern physics. An example are the Onsager relations between coefficients connecting thermodynamic fluxes and forces, central to transport theory and experiments. Initially formulated for classical systems, these reciprocity relations are also fulfilled in quantum conductors. Surprisingly, novel relations have been predicted specifically for thermoelectric transport. However, whereas these thermoelectric reciprocity relations have to date not been verified, they have been predicted to be sensitive to inelastic scattering, always present at finite temperature. The question whether the relations exist in practice is important for thermoelectricity: whereas their existence may simplify the theory of complex thermoelectric materials, their absence has been shown to enable, in principle, higher thermoelectric energy conversion efficiency for a given material quality. Here we experimentally verify the thermoelectric reciprocity relations in a four-terminal mesoscopic device where each terminal can be electrically and thermally biased, individually. The linear response thermoelectric coefficients are found to be symmetric under simultaneous reversal of magnetic field and exchange of injection and emission contacts. Intriguingly, we also observe the breakdown of the reciprocity relations as a function of increasing thermal bias. Our measurements thus clearly establish the existence of the thermoelectric reciprocity relations, as well as the possibility to control their breakdown with the potential to enhance thermoelectric performanceComment: 7 pages, 5 figure

    Space shuttle: Heat transfer rate measurements on Convair booster (B-15B-2) at nominal Mach number of 8

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    Plotted and tabulated data on heat transfer from a thin-skin thermocouple are presented. The data is representative of the reentry event of the booster alone configuration. The data were generated during wind tunnel tests of the B-15B-2 delta wing booster at Mach 8. Thermocouple measurements are reduced to heat transfer coefficient ratio and the data are presented as plotted variations versus longitudinal, lateral, and vertical local model positions
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