31 research outputs found

    Investigations of solutions of Einstein's field equations close to lambda-Taub-NUT

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    We present investigations of a class of solutions of Einstein's field equations close to the family of lambda-Taub-NUT spacetimes. The studies are done using a numerical code introduced by the author elsewhere. One of the main technical complication is due to the S3-topology of the Cauchy surfaces. Complementing these numerical results with heuristic arguments, we are able to yield some first insights into the strong cosmic censorship issue and the conjectures by Belinskii, Khalatnikov, and Lifschitz in this class of spacetimes. In particular, the current investigations suggest that strong cosmic censorship holds in this class. We further identify open issues in our current approach and point to future research projects.Comment: 24 pages, 12 figures, uses psfrag and hyperref; replaced with published version, only minor corrections of typos and reference

    Bayesian inference on compact binary inspiral gravitational radiation signals in interferometric data

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    Presented is a description of a Markov chain Monte Carlo (MCMC) parameter estimation routine for use with interferometric gravitational radiational data in searches for binary neutron star inspiral signals. Five parameters associated with the inspiral can be estimated, and summary statistics are produced. Advanced MCMC methods were implemented, including importance resampling and prior distributions based on detection probability, in order to increase the efficiency of the code. An example is presented from an application using realistic, albeit fictitious, data.Comment: submitted to Classical and Quantum Gravity. 14 pages, 5 figure

    Inference on inspiral signals using LISA MLDC data

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    In this paper we describe a Bayesian inference framework for analysis of data obtained by LISA. We set up a model for binary inspiral signals as defined for the Mock LISA Data Challenge 1.2 (MLDC), and implemented a Markov chain Monte Carlo (MCMC) algorithm to facilitate exploration and integration of the posterior distribution over the 9-dimensional parameter space. Here we present intermediate results showing how, using this method, information about the 9 parameters can be extracted from the data.Comment: Accepted for publication in Classical and Quantum Gravity, GWDAW-11 special issu

    The potential of urinary metabolites for diagnosing multiple sclerosis

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    A definitive diagnostic test for multiple sclerosis (MS) does not exist; instead physicians use a combination of medical history, magnetic resonance imaging, and cerebrospinal fluid analysis (CSF). Significant effort has been employed to identify biomarkers from CSF to facilitate MS diagnosis; however none of the proposed biomarkers have been successful to date. Urine is a proven source of metabolite biomarkers and has the potential to be a rapid, non-invasive, inexpensive, and efficient diagnostic tool for various human diseases. Nevertheless, urinary metabolites have not been extensively explored as a source of biomarkers for MS. Instead, we demonstrate that urinary metabolites have significant promise for monitoring disease-progression, and response to treatment in MS patients. NMR analysis of urine permitted the identification of metabolites that differentiate experimental autoimmune encephalomyelitis (EAE)-mice (prototypic disease model for MS) from healthy and MS drug-treated EAE mice

    Guidelines for the use and interpretation of assays for monitoring autophagy (3rd edition)

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    In 2008 we published the first set of guidelines for standardizing research in autophagy. Since then, research on this topic has continued to accelerate, and many new scientists have entered the field. Our knowledge base and relevant new technologies have also been expanding. Accordingly, it is important to update these guidelines for monitoring autophagy in different organisms. Various reviews have described the range of assays that have been used for this purpose. Nevertheless, there continues to be confusion regarding acceptable methods to measure autophagy, especially in multicellular eukaryotes. For example, a key point that needs to be emphasized is that there is a difference between measurements that monitor the numbers or volume of autophagic elements (e.g., autophagosomes or autolysosomes) at any stage of the autophagic process versus those that measure fl ux through the autophagy pathway (i.e., the complete process including the amount and rate of cargo sequestered and degraded). In particular, a block in macroautophagy that results in autophagosome accumulation must be differentiated from stimuli that increase autophagic activity, defi ned as increased autophagy induction coupled with increased delivery to, and degradation within, lysosomes (inmost higher eukaryotes and some protists such as Dictyostelium ) or the vacuole (in plants and fungi). In other words, it is especially important that investigators new to the fi eld understand that the appearance of more autophagosomes does not necessarily equate with more autophagy. In fact, in many cases, autophagosomes accumulate because of a block in trafficking to lysosomes without a concomitant change in autophagosome biogenesis, whereas an increase in autolysosomes may reflect a reduction in degradative activity. It is worth emphasizing here that lysosomal digestion is a stage of autophagy and evaluating its competence is a crucial part of the evaluation of autophagic flux, or complete autophagy. Here, we present a set of guidelines for the selection and interpretation of methods for use by investigators who aim to examine macroautophagy and related processes, as well as for reviewers who need to provide realistic and reasonable critiques of papers that are focused on these processes. These guidelines are not meant to be a formulaic set of rules, because the appropriate assays depend in part on the question being asked and the system being used. In addition, we emphasize that no individual assay is guaranteed to be the most appropriate one in every situation, and we strongly recommend the use of multiple assays to monitor autophagy. Along these lines, because of the potential for pleiotropic effects due to blocking autophagy through genetic manipulation it is imperative to delete or knock down more than one autophagy-related gene. In addition, some individual Atg proteins, or groups of proteins, are involved in other cellular pathways so not all Atg proteins can be used as a specific marker for an autophagic process. In these guidelines, we consider these various methods of assessing autophagy and what information can, or cannot, be obtained from them. Finally, by discussing the merits and limits of particular autophagy assays, we hope to encourage technical innovation in the field

    Measurement of the phase difference between short- and long-distance amplitudes in the B+K+μ+μB^{+}\to K^{+}\mu^{+}\mu^{-} decay

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    A measurement of the phase difference between the short- and long-distance contributions to the B+K+μ+μB^{+}\to K^{+}\mu^{+}\mu^{-} decay is performed by analysing the dimuon mass distribution. The analysis is based on pppp collision data corresponding to an integrated luminosity of 3 fb1\rm fb^{-1} collected by the LHCb experiment in 2011 and 2012. The long-distance contribution to the B+K+μ+μB^{+}\to K^{+}\mu^{+}\mu^{-} decay is modelled as a sum of relativistic Breit--Wigner amplitudes representing different vector meson resonances decaying to muon pairs, each with their own magnitude and phase. The measured phases of the J/ψJ/\psi and ψ(2S)\psi(2S) resonances are such that the interference with the short-distance component in dimuon mass regions far from their pole masses is small. In addition, constraints are placed on the Wilson coefficients, C9\mathcal{C}_{9} and C10\mathcal{C}_{10}, and the branching fraction of the short-distance component is measured.Comment: 23 pages, 4 figures, published in EPJC. All figures and tables, along with any supplementary material and additional information, are available at http://lhcbproject.web.cern.ch/lhcbproject/Publications/LHCbProjectPublic/LHCb-PAPER-2016-045.htm

    Sistemas de mensuração e avaliação de desempenho organizacional: estudo de casos no setor químico no Brasil Organizational performance measurement and evaluation systems: multiple case study in the Brazilian chemical sector

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    O artigo pretende apresentar os resultados de uma pesquisa realizada junto a quatro grandes empresas brasileiras do setor químico, descrevendo os seus respectivos sistemas de mensuração e avaliação de desempenho organizacional. O presente trabalho é um estudo exploratório e descritivo e baseia-se no uso de estudos de casos múltiplos, tendo sido realizada a respectiva revisão da literatura que aborda o assunto. São propostas, ao final, as conclusões e recomendações que se fazem pertinentes ao tema do trabalho, guardadas as restrições próprias da metodologia empregada.<br>The objectives of this paper are to present some results of a research carried out in four large chemical companies operating in Brazil and to describe these companies' organizational performance measurement and evaluation systems. This is an exploratory and descriptive research based on multiple case studies, in accordance with a literature review on this subject. At the end, some conclusions and recommendations are presented, despite the limitations characteristic of the applied methodology
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