2,991 research outputs found

    The Great Snake Hunt

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    Degree of randomness: numerical experiments for astrophysical signals

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    Astrophysical and cosmological signals such as the cosmic microwave background radiation, as observed, typically contain contributions of different components, and their statistical properties can be used to distinguish one from the other. A method developed originally by Kolmogorov is involved for the study of astrophysical signals of randomness of various degrees. Numerical performed experiments based on the universality of Kolmogorov distribution and using a single scaling of the ratio of stochastic to regular components, reveal basic features in the behavior of generated signals also in terms of a critical value for that ratio, thus enable the application of this technique for various observational datasetsComment: 6 pages, 9 figures; Europhys.Letters; to match the published versio

    Development of responder definitions for fibromyalgia clinical trials

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    Objective To develop responder definitions for fibromyalgia (FM) clinical trials using key symptom and function domains. Methods Twenty‐four candidate responder definitions were developed by expert consensus and were evaluated in 12 randomized, placebo‐controlled trials of 4 medications for the treatment of FM. For each definition, the treatment effects of the medication compared with placebo were analyzed using Cochran‐Mantel‐Haenszel tests or chi‐square tests. A meta‐analysis of the pooled results for the 4 medications established risk ratios to determine the definitions that best favored medication over placebo. Results Two definitions performed best in the analyses. Both definitions included ≄30% reduction in pain and ≄10% improvement in physical function. The definitions differed in that one (≄30% improvement in FM [FM30] short version) included ≄30% improvement in sleep or fatigue, and the other (FM30 long version) required ≄30% improvement in 2 of the following symptoms: sleep, fatigue, depression, anxiety, or cognition. In the analysis of both versions, the response rate was ≄15% for each medication and was significantly greater compared with placebo. The risk ratio favoring drug over placebo in the pooled analysis for FM30 version 3 (short version) was 1.50 (95% confidence interval [95% CI] 1.24–1.82; P ≀ 0.0001); the risk ratio for FM30 version 6 (long version) was 1.60 (95% CI 1.31–1.96; P ≀ 0.00001). Conclusion Among the 24 responder definitions tested, 2 were identified as most sensitive in identifying response to treatment. The identification of responder definitions for FM clinical trials that include assessments of key symptom and function domains may improve the sensitivity of clinical trials to identify meaningful improvements, leading to improved management of FM.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/90281/1/33360_ftp.pd

    Chemoenzymatic elaboration of monosaccharides using engineered cytochrome P450_(BM3) demethylases

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    Polysaccharides comprise an extremely important class of biopolymers that play critical roles in a wide range of biological processes, but the synthesis of these compounds is challenging because of their complex structures. We have developed a chemoenzymatic method for regioselective deprotection of monosaccharide substrates using engineered Bacillus megaterium cytochrome P450 (P450_(BM3)) demethylases that provides a highly efficient means to access valuable intermediates, which can be converted to a wide range of substituted monosaccharides and polysaccharides. Demethylases displaying high levels of regioselectivity toward a number of protected monosaccharides were identified using a combination of protein and substrate engineering, suggesting that this approach ultimately could be used in the synthesis of a wide range of substituted mono- and polysaccharides for studies in chemistry, biology, and medicine

    Separability Criterion for all bipartite Gaussian States

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    We provide a necessary and sufficient condition for separability of Gaussian states of bipartite systems of arbitrarily many modes. The condition provides an operational criterion since it can be checked by simple computation. Moreover, it allows us to find a pure product-state decomposition of any given separable Gaussian state. Our criterion is independent of the one based on partial transposition, and is strictly stronger.Comment: 4 pages, 1 figure (.eps

    Feature relative navigation for automous underwater vehicles

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    Thesis (Ph. D.)--Massachusetts Institute of Technology, Dept. of Ocean Engineering, 1997.Includes bibliographical references (leaves 184-196).by Andrew Arnold Bennett.Ph.D

    Calculations of parity nonconserving s-d transitions in Cs, Fr, Ba II, and Ra II

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    We have performed ab initio mixed-states and sum-over-states calculations of parity nonconserving (PNC) electric dipole (E1) transition amplitudes between s-d electron states of Cs, Fr, Ba II, and Ra II. For the lower states of these atoms we have also calculated energies, E1 transition amplitudes, and lifetimes. We have shown that PNC E1 transition amplitudes between s-d states can be calculated to high accuracy. Contrary to the Cs 6s-7s transition, in these transitions there are no strong cancelations between different terms in the sum-over-states approach. In fact, there is one dominating term which deviates from the sum by less than 20%. This term corresponds to an s-p_{1/2} weak matrix element, which can be calculated to better than 1%, and a p_{1/2}-d_{3/2} E1 transition amplitude, which can be measured. Also, the s-d amplitudes are about four times larger than the corresponding s-s transitions. We have shown that by using a hybrid mixed-states/sum-over-states approach the accuracy of the calculations of PNC s-d amplitudes could compete with that of Cs 6s-7s if p_{1/2}-d_{3/2} E1 amplitudes are measured to high accuracy.Comment: 15 pages, 8 figures, submitted to Phys. Rev.
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