7,155 research outputs found

    Nonlocality, Bell's Ansatz and Probability

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    Quantum Mechanics lacks an intuitive interpretation, which is the cause of a generally formalistic approach to its use. This in turn has led to a certain insensitivity to the actual meaning of many words used in its description and interpretation. Herein, we analyze carefully the possible mathematical meanings of those terms used in analysis of EPR's contention, that Quantum Mechanics is incomplete, as well as Bell's work descendant therefrom. As a result, many inconsistencies and errors in contemporary discussions of nonlocality, as well as in Bell's Ansatz with respect to the laws of probability, are identified. Evading these errors precludes serious conflicts between Quantum Mechanics and both Special Relativity and Philosophy.Comment: 8&1/2 pages revtex; v2: many corrections, clairifications & extentions, all small; v3: editorial scru

    Fixed Effect Estimation of Large T Panel Data Models

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    This article reviews recent advances in fixed effect estimation of panel data models for long panels, where the number of time periods is relatively large. We focus on semiparametric models with unobserved individual and time effects, where the distribution of the outcome variable conditional on covariates and unobserved effects is specified parametrically, while the distribution of the unobserved effects is left unrestricted. Compared to existing reviews on long panels (Arellano and Hahn 2007; a section in Arellano and Bonhomme 2011) we discuss models with both individual and time effects, split-panel Jackknife bias corrections, unbalanced panels, distribution and quantile effects, and other extensions. Understanding and correcting the incidental parameter bias caused by the estimation of many fixed effects is our main focus, and the unifying theme is that the order of this bias is given by the simple formula p/n for all models discussed, with p the number of estimated parameters and n the total sample size.Comment: 40 pages, 1 tabl

    КЛИНИЧЕСКИЕ И ПАТОМОРФОЛОГИЧЕСКИЕ ПРОЯВЛЕНИЯ ТЯЖЕЛОЙ РЕСПИРАТОРНО-СИНЦИТИАЛЬНОЙ ВИРУСНОЙ ИНФЕКЦИИ. СЛУЧАЙ ИЗ ПРАКТИКИ

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    On the example of clinical observation of severe respiratory syncytial virus (RSV) infection, which occurred with the development of a specific pneumonia complicated by acute respiratory distress-syndrome and disseminated intravascular coagulation syndrome, which caused a lethal outcome in the non-term (33-34 weeks gestation) child of two months of life, the clinical and pathomorphological features of the disease are shown. Immunomorphologic study after death allowed to demonstrate the most important stages of respiratory syncytial viral infection pathogenesis and to specify reasons of long-term airway obstruction, caused by complicated respiratory syncytial viral infection. It was indicated, that bronchial obstruction may be caused by qualitative changes of epithelial lumen of different bronchi, such as direct cytophatic effect of respiratory virus or reactive changes of lumen in the form of basal squamous cell differentiation of epithelial lumen and poor regeneration of respiratory epithelium in the later stages of the disease. На примере клинического наблюдения тяжелой респираторно-синцитиальной вирусной (РСВ) инфекции, протекавшей с развитием специфической пневмонии, осложненной острым респираторным дистресс-синдромом и синдромом диссеминированного внутрисосудистого свертывания, обусловившими летальный исход у недоношенного (33–34 недели гестации) ребенка двух месяцев жизни, показаны клинические и патоморфологические особенности заболевания. Использование постмортального посмертного иммуноморфологического исследования позволило продемонстрировать важнейшие звенья патогенеза РСВ-инфекции, а также уточнить причины длительной бронхообструкции при ее тяжелом течении. Показано, что на поздних сроках заболевания в основе бронхообструкции лежат качественные изменения эпителиальной выстилки бронхов разного калибра, обусловленные как сохраняющимся цитопатическим действием РСВ, так и реактивными изменениями эпителия в виде базальной плоскоклеточной дифференцировки эпителиального пласта при слабо выраженной регенерации респираторного эпителия.

    Limits on WWgamma and WWZ Couplings from W Boson Pair Production

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    The results of a search for W boson pair production in pbar-p collisions at sqrt{s}=1.8 TeV with subsequent decay to emu, ee, and mumu channels are presented. Five candidate events are observed with an expected background of 3.1+-0.4 events for an integrated luminosity of approximately 97 pb^{-1}. Limits on the anomalous couplings are obtained from a maximum likelihood fit of the E_T spectra of the leptons in the candidate events. Assuming identical WWgamma and WWZ couplings, the 95 % C.L. limits are -0.62<Delta_kappa<0.77 (lambda = 0) and -0.53<lambda<0.56 (Delta_kappa = 0) for a form factor scale Lambda = 1.5 TeV.Comment: 10 pages, 1 figure, submitted to Physical Review

    Confirmation of the Double Charm Baryon Xi_cc+ via its Decay to p D+ K-

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    We observes a signal for the double charm baryon Xi_cc+ in the charged decay mode Xi_cc+ -> p D+ K- to complement the previously reported decay Xi_cc+ -> Lambda_c K- pi+ in data from SELEX, the charm hadro-production experiment (E781) at Fermilab. In this new decay mode we observe an excess of 5.62 events over an expected background estimated by event mixing to be 1.38+/-0.13 events. The Poisson probability that a background fluctuation can produce the apparent signal is less than 6.4E-4. The observed mass of this state is (3518+/-3)MeV/c^2, consistent with the published result. Averaging the two results gives a mass of (3518.7+/-1.7)MeV/c^2. The observation of this new weak decay mode confirms the previous SELEX suggestion that this state is a double charm baryon. The relative branching ratio Gamma(Xi_cc+ -> pD+K-)/Gamma(Xi_cc+ -> Lambda_c K- pi+) = 0.36+/-0.21.Comment: 11 pages, 6 included eps figures. v2 includes improved statistical method to determine significance of observation. Submitted to PL

    A New Measurement of the π0\pi^0 Radiative Decay Width

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    High precision measurements of the differential cross sections for π0\pi^0 photoproduction at forward angles for two nuclei, 12^{12}C and 208^{208}Pb, have been performed for incident photon energies of 4.9 - 5.5 GeV to extract the π0γγ{\pi^0 \to \gamma\gamma} decay width. The experiment was done at Jefferson Lab using the Hall B photon tagger and a high-resolution multichannel calorimeter. The π0γγ{\pi^0 \to \gamma\gamma} decay width was extracted by fitting the measured cross sections using recently updated theoretical models for the process. The resulting value for the decay width is Γ(π0γγ)=7.82±0.14 (stat.)±0.17 (syst.) eV\Gamma{(\pi^0 \to \gamma\gamma)} = 7.82 \pm 0.14 ~({\rm stat.}) \pm 0.17 ~({\rm syst.}) ~{\rm eV}. With the 2.8% total uncertainty, this result is a factor of 2.5 more precise than the current PDG average of this fundamental quantity and it is consistent with current theoretical predictions.Comment: 4 pages, 5 figure

    MouseIndelDB: a database integrating genomic indel polymorphisms that distinguish mouse strains

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    MouseIndelDB is an integrated database resource containing thousands of previously unreported mouse genomic indel (insertion and deletion) polymorphisms ranging from ∼100 nt to 10 Kb in size. The database currently includes polymorphisms identified from our alignment of 26 million whole-genome shotgun sequence traces from four laboratory mouse strains mapped against the reference C57BL/6J genome using GMAP. They can be queried on a local level by chromosomal coordinates, nearby gene names or other genomic feature identifiers, or in bulk format using categories including mouse strain(s), class of polymorphism(s) and chromosome number. The results of such queries are presented either as a custom track on the UCSC mouse genome browser or in tabular format. We anticipate that the MouseIndelDB database will be widely useful for research in mammalian genetics, genomics, and evolutionary biology. Access to the MouseIndelDB database is freely available at: http://variation.osu.edu/

    First Observation of the Doubly Charmed Baryon Xi_cc^+

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    We observe a signal for the doubly charmed baryon Xi_cc^+ in the charged decay mode Xi_cc^+ --> Lambda_c^+ K- pi+ in data from SELEX, the charm hadro-production experiment at Fermilab. We observe an excess of 15.9 events over an expected background of 6.1 +/- 0.5 events, a statistical significance of 6.3sigma. The observed mass of this state is (3519 +/- 1) MeV/c^2. The Gaussian mass width of this state is 3MeV/c^2, consistent with resolution; its lifetime is less than 33fsec at 90% confidence.Comment: 5 pages, 3 figures, accepted for publication in Physical Review Letter
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