39,165 research outputs found

    Lost City meteorite: Its recovery and a comparison with other fireballs

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    Lost City meteoroid trajectory analysis and determination of original mas

    La cuántica se consideraba una pérdida de tiempo

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    Entrevista realizada en el marco de las actividades del Curso de Periodismo Cultural de Revista de Letras.Peer Reviewe

    Random field Ising systems on a general hierarchical lattice: Rigorous inequalities

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    Random Ising systems on a general hierarchical lattice with both, random fields and random bonds, are considered. Rigorous inequalities between eigenvalues of the Jacobian renormalization matrix at the pure fixed point are obtained. These inequalities lead to upper bounds on the crossover exponents {ϕi}\{\phi_i\}.Comment: LaTeX, 13 pages, figs. 1a,1b,2. To be published in PR

    Lost City meteorite - It's recovery and a comparison with other fireballs

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    Photographic and trajectory data for Lost City meteor and establishment of calibration of mass scale of other meteor

    The nature of the long time decay at a second order transition point

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    We show that at a second order phase transition, of \phi^4 like system, a necessary condition for streched exponential decay of the time structure factor is obeyed. Using the ideas presented in this proof a crude estimate of the decay of the structure factor is obtained and shown to yield stretched exponential decay under very reasonable conditions.Comment: 7 page

    Evaluation of African-American and White Racial Classification in a Surveillance, Epidemiology, and End Results Cancer Registry

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    Objectives: This study evaluated the validity of registry-reported race for individuals who participated in research studies conducted since 1980 through the Metropolitan Detroit Cancer Surveillance System (MDCSS), a Surveillance, Epidemiology, and End Results (SEER) Program registry. Methods: 5329 individuals who self-identified as African American or White and were classified in the MDCSS registry as African American or White were included. Self-identified and registry-reported race were compared, and associations between demographics and racial misclassification were examined. Results: Most self-identified African Americans and Whites were correctly classified (sensitivity= 98.5%, specificity=99.7%). Males were two times more likely to be misclassified than females [odds ratio (OR)=2.13, 95% confidence interval (CI): 1.06-4.29]. Individuals diagnosed with cancer after 1990 were two times more likely to be misclassified than those diagnosed before 1990 (OR= 2.17, 95% CI: 1.07--4.42). African Americans were four times more likely to be misclassified than Whites (OR=4.39, 95% CI: 2.24-8.60). Conclusions: Misclassification in the MDCSS registry of African Americans as Whites, and vice versa, is relatively low. Additional studies should evaluate misclassification of African Americans and Whites as other races and/or ethnicities in the SEER registry

    Using network analysis for the prediction of treatment dropout in patients with mood and anxiety disorders: a methodological proof-of-concept study

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    There are large health, societal, and economic costs associated with attrition from psychological services. The recently emerged, innovative statistical tool of complex network analysis was used in the present proof-of-concept study to improve the prediction of attrition. Fifty-eight patients undergoing psychological treatment for mood or anxiety disorders were assessed using Ecological Momentary Assessments four times a day for two weeks before treatment (3,248 measurements). Multilevel vector autoregressive models were employed to compute dynamic symptom networks. Intake variables and network parameters (centrality measures) were used as predictors for dropout using machine-learning algorithms. Networks for patients differed significantly between completers and dropouts. Among intake variables, initial impairment and sex predicted dropout explaining 6% of the variance. The network analysis identified four additional predictors: Expected force of being excited, outstrength of experiencing social support, betweenness of feeling nervous, and instrength of being active. The final model with the two intake and four network variables explained 32% of variance in dropout and identified 47 out of 58 patients correctly. The findings indicate that patients’ dynamic network structures may improve the prediction of dropout. When implemented in routine care, such prediction models could identify patients at risk for attrition and inform personalized treatment recommendations.This work was supported by the German Research Foundation National Institute (DFG, Grant nos. LU 660/8-1 and LU 660/10-1 to W. Lutz). The funder of the study had no role in study design, data collection, data analysis, data interpretation, or writing of the manuscript. The corresponding author had access to all data in the study and had final responsibility for the decision to submit for publication. Dr. Hofmann receives financial support from the Alexander von Humboldt Foundation (as part of the Humboldt Prize), NIH/NCCIH (R01AT007257), NIH/NIMH (R01MH099021, U01MH108168), and the James S. McDonnell Foundation 21st Century Science Initiative in Understanding Human Cognition - Special Initiative. (LU 660/8-1 - German Research Foundation National Institute (DFG); LU 660/10-1 - German Research Foundation National Institute (DFG); Alexander von Humboldt Foundation; R01AT007257 - NIH/NCCIH; R01MH099021 - NIH/NIMH; U01MH108168 - NIH/NIMH; James S. McDonnell Foundation 21st Century Science Initiative in Understanding Human Cognition - Special Initiative)Accepted manuscrip

    Lexicographic choice functions without archimedeanicity

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    We investigate the connection between choice functions and lexicographic probabilities, by means of the convexity axiom considered by Seidenfeld, Schervisch and Kadane (2010) but without imposing any Archimedean condition. We show that lexicographic probabilities are related to a particular type of sets of desirable gambles, and investigate the properties of the coherent choice function this induces via maximality. Finally, we show that the convexity axiom is necessary but not sufficient for a coherent choice function to be the infimum of a class of lexicographic ones

    About Superluminal motions and Special Relativity: A Discussion of some recent Experiments, and the solution of the Causal Paradoxes

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    Some experiments, performed at Berkeley, Cologne, Florence, Vienna, Orsay, Rennes, etc., led to the claim that something seems to travel with a group velocity larger than the speed c of light in vacuum. Various other experimental results seem to point in the same direction: For instance, localized wavelet- type solutions to Maxwell equations have been found, both theoretically and experimentally, that travel with superluminal speed. [Even muonic and electronic neutrinos [it has been proposed] might be "tachyons", since their square mass appears to be negative]. With regard to the first-mentioned experiments, it was recently claimed by Guenter Nimtz that those results with evanescent waves (or tunneling photons) imply superluminal signal and impulse transmission, and therefore violate Einstein causality. In this note we want to stress that, on the contrary, all such results do not place relativistic causality in jeopardy, even if they referred to actual tachyonic motions: In fact, Special Relativity can cope even with superluminal objects and waves. For instance, it is possible (at least in microphysics) to solve also the known causal paradoxes, devised for faster than light motion, although this is not widely recognized yet. Here we show, in detail and rigorously, how to solve the oldest causal paradox, originally proposed by Tolman, which is the kernel of many further tachyon paradoxes (like J.Bell's, F.A.E.Pirani's, J.D.Edmonds' and others'). The key to the solution is a careful application of tachyon mechanics, as it unambiguously follows from special relativity. At Last, in one of the two Appendices, we propose how to evaluate the group-velocity in the case of evanescent waves. [PACS nos.: 03.30.+p; 03.50.De; 41.20.Jb; 73.40.Gk; 84.40.Az; 42.82.Et ]Comment: LaTeX file: 26 pages, with 5 Figures (and two Appendices). The original version of this paper appeared in the Journal below

    The complete Hard X Ray Burst Spectrometer event list, 1980-1989

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    This event list is a comprehensive reference for all Hard X ray bursts detected with the Hard X Ray Burst Spectrometer on the Solar Maximum Mission from the time of launch on Feb. 14, 1980 to the end of the mission in Dec. 1989. Some 12,776 events were detected in the energy range 30 to 600 keV with the vast majority being solar flares. This list includes the start time, peak time, duration, and peak rate of each event
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