31,705 research outputs found

    Magnetic blackbody shift of hyperfine transitions for atomic clocks

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    We derive an expression for the magnetic blackbody shift of hyperfine transitions such as the cesium primary reference transition which defines the second. The shift is found to be a complicated function of temperature, and has a T^2 dependence only in the high-temperature limit. We also calculate the shift of ground-state p_1/2 hyperfine transitions which have been proposed as new atomic clock transitions. In this case interaction with the p_3/2 fine-structure multiplet may be the dominant effect

    New spectral observations of Callisto and leading/trailing hemisphere distinctions

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    In December 1989 and January 1990, new observations of the leading and trailing edges of Callisto were made from the NASA Infrared Telescope Facility on Mauna Kea in Hawaii. Using the Cool Grating Array Spectrometer, spectral coverage was obtained from 1.89 to 2.46 microns and from 2.8 to 4.2 microns for both the leading and trailing hemispheres. In addition, spectral coverage of the leading hemisphere was obtained from 1.30 to 2.55 microns and from 4.2 to 4.8 microns. Interpretations of the data are given

    Rotating Metal Band Target for Pion Production at Muon Colliders and Neutrino Factories

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    A conceptual design is presented for a high power pion production target for muon colliders and neutrino factories that is based around a rotating metal band.Comment: 28 pages, 16 figures; to be published in Phys. Rev. ST Accel. Beam

    Differential constraints and exact solutions of nonlinear diffusion equations

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    The differential constraints are applied to obtain explicit solutions of nonlinear diffusion equations. Certain linear determining equations with parameters are used to find such differential constraints. They generalize the determining equations used in the search for classical Lie symmetries

    Scaling of the distribution of shortest paths in percolation

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    We present a scaling hypothesis for the distribution function of the shortest paths connecting any two points on a percolating cluster which accounts for {\it (i)} the effect of the finite size of the system, and {\it (ii)} the dependence of this distribution on the site occupancy probability pp. We test the hypothesis for the case of two-dimensional percolation.Comment: 7 pages, 3 figure

    New flaring of an ultraluminous X-ray source in NGC 1365

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    We have studied a highly variable ultraluminous X-ray source (ULX) in the Fornax galaxy NGC 1365, with a series of 12 Chandra and XMM-Newton observations between 2002 and 2006. In 2006 April, the source peaked at a luminosity ~ 3 x 10^{40} erg/s in the 0.3-10 keV band (similar to the maximum luminosity found by ASCA in 1995), and declined on an e-folding timescale ~ 3 days. The X-ray spectrum is always dominated by a broad power-law-like component. When the source is seen at X-ray luminosities ~ 10^{40} erg/s, an additional soft thermal component (which we interpret as emission from the accretion disk) contributes ~ 1/4 of the X-ray flux; when the luminosity is higher, ~ 3 x 10^{40} erg/s, the thermal component is not detected and must contribute < 10% of the flux. At the beginning of the decline, ionized absorption is detected around 0.5-2 keV; it is a possible signature of a massive outflow. The power-law is always hard, with a photon index Gamma ~ 1.7 (and even flatter at times), as is generally the case with bright ULXs. We speculate that this source and perhaps most other bright ULXs are in a high/hard state: as the accretion rate increases well above the Eddington limit, more and more power is extracted from the inner region of the inflow through non-radiative channels, and is used to power a Comptonizing corona, jet or wind. The observed thermal component comes from the standard outer disk; the transition radius between outer standard disk and Comptonizing inner region moves further out and to lower disk temperatures as the accretion rate increases. This produces the observed appearance of a large, cool disk. Based on X-ray luminosity and spectral arguments, we suggest that this accreting black hole has a likely mass ~ 50-150 Msun (even without accounting for possible beaming).Comment: 14 pages, to appear in MNRA

    Kuantitas Penggunaan Antibiotik Sebelum Dan Setelah Pembuatan Pedoman Penggunaan Antibiotik (Ppab) Penelitian Pada Kasus Bedah Digestif Rsup Dr. Kariadi Semarang

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    Background Pedoman Penggunaan Antibiotik (PPAB) is a book containing procedures and guides for using antibiotic properly. After the new revision, antibiotic prescription is expected to be proper with the written guidelines.Aim To measure quantity of antibiotic use in digestive cases before and after the making of PPAB.Methods This study is a prospective observational study. Subjects were patients in digestive surgery case hospitalizing in September and November. The use of antibiotic is compared between period of before and after the making of PPAB (October) using independent t test and Mann-Whitney test.Result DDD/100 patient days of antibiotic prophylaxis before the making of PPAB is 13,54 decrease to 11,96 after the making of PPAB, but the decrease is not significantly different in statistic test. The most antibiotic prophylaxis (ceftriaxone) before the making of PPAB (13,13 DDD/100 patient days) declined (11,18 DDD/100 patient days) after the making of PPAB. Quantity of antibiotic prophylaxis use of sefazolin before the making of PPAB is 0,42 DDD/patient days increase to 0,78 DD/100 patient days after the making of PPAB.Conclusion There is no significant changes of quantity of antibiotic cefazolin-ceftriaxone for prophylaxis in digestive surgical case between before and after the making of PPAB. Needed socialization, education, and trainin

    The Retail FX Trader: Random Trading and the Negative Sum Game

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    With the internet boom of early 2000 making access to trading the Foreign Exchange (FX) market far simpler for members of the general public, the growth of 'retail' FX trading continues, with daily transaction volumes as high as $200 billion. Potential new entrants to the retail FX trading world may come from the recent UK pension deregulations, further increasing the volumes. The attraction of FX trading is that it offers high returns and whilst it has been understood that it is high-risk in nature, the rewards are seen as being commensurately high for the 'skilled and knowledgeable' trader who has an edge over other market participants. This paper analyses a number of independent sources of data and previous research, to examine the profitability of the Retail FX trader and compares the results with that of a simulated random trading models. This paper finds evidence to suggest that whilst approximately 20% of traders can expect to end up with a profitable account, around 40% might expect their account to be subject to a margin call. This paper finds a strong correlation between the overall profitability of traders and impact of the cost of the bid-ask spread, whilst finding little if any evidence that retail FX traders, when viewed as a group, are achieving results better than that from random trading
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