8,378 research outputs found

    Signals for Noncommutative QED at Future e+e−e^+e^- Colliders

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    The signatures for noncommutative QED at e+e−e^+e^- colliders with center of mass energies in the range of 0.5-5 TeV are examined. For integrated luminosities of 0.5-1 ab−1^{-1} or more, sensitivities to the associated mass scales greater than s\sqrt s are possible.Comment: LaTex, 6 pages, 6 figs; to appear in the Proceedings of the Fourth International Workshop on e−e−e^-e^- Interactions at TeV Energies, UC Santa Cruz, 7-9 Dec 200

    Chaos in temperature in the Sherrington-Kirkpatrick model

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    We prove the existence of chaos in temperature in the Sherringhton-Kirkpatrick model. The effect is exceedingly small, namely of the ninth order in perturbation theory. The equations describing two systems at different temperatures constrained to have a fixed overlap are studied analytically and numerically, yielding information about the behaviour of the overlap distribution function PT1,T2(q)P_{T_1,T_2}(q) in finite-size systems.Comment: REVTEX, 6 pages, 2 figure

    Estimating transmission probability in schools for the 2009 H1N1 influenza pandemic in Italy

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    BACKGROUND: Epidemic models are being extensively used to understand the main pathways of spread of infectious diseases, and thus to assess control methods. Schools are well known to represent hot spots for epidemic spread; hence, understanding typical patterns of infection transmission within schools is crucial for designing adequate control strategies. The attention that was given to the 2009 A/H1N1pdm09 flu pandemic has made it possible to collect detailed data on the occurrence of influenza-like illness (ILI) symptoms in two primary schools of Trento, Italy. RESULTS: The data collected in the two schools were used to calibrate a discrete-time SIR model, which was designed to estimate the probabilities of influenza transmission within the classes, grades and schools using Markov Chain Monte Carlo (MCMC) methods. We found that the virus was mainly transmitted within class, with lower levels of transmission between students in the same grade and even lower, though not significantly so, among different grades within the schools. We estimated median values of R 0 from the epidemic curves in the two schools of 1.16 and 1.40; on the other hand, we estimated the average number of students infected by the first school case to be 0.85 and 1.09 in the two schools. CONCLUSIONS: The discrepancy between the values of R 0 estimated from the epidemic curve or from the within-school transmission probabilities suggests that household and community transmission played an important role in sustaining the school epidemics. The high probability of infection between students in the same class confirms that targeting within-class transmission is key to controlling the spread of influenza in school settings and, as a consequence, in the general population

    Comparison of dynamical multifragmentation models

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    Multifragmentation scenarios, as predicted by antisymmetrized molecular dynamics (AMD) or momentum-dependent stochastic mean-field (BGBD) calculations are compared. While in the BGBD case fragment emission is clearly linked to the spinodal decomposition mechanism, i.e. to mean-field instabilities, in AMD many-body correlations have a stronger impact on the fragmentation dynamics and clusters start to appear at earlier times. As a consequence, fragments are formed on shorter time scales in AMD, on about equal footing of light particle pre-equilibrium emission. Conversely, in BGBD pre-equilibrium and fragment emissions happen on different time scales and are related to different mechanisms

    Regulation

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    Insegnare nelle Universit\ue0 la Fitoterapia e l\u2019Agopuntura?

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    According to National Center for Complementary and Alternative Medicine (CAM) of NIH, the CAM terms are used to mean the array of health care approaches with a history of use or origins outside of mainstream medicine. Numerous surveys document high level of interest in use of CAM among the Western public, hence raising the matter of their study in the medical education. Several scientists have subjected CAM interventions to the same methodological scrutiny responsible for the progress of Western clinical medicine (that is evidence based), i.e. with the standard of randomized controlled trials. So, the purpose of this paper was to review the scientific evidences of two particular CAM, Phytotherapy and Acupuncture, to evaluate their possible involvement in the medical education.

    Large Deviations of the Free-Energy in Diluted Mean-Field Spin-Glass

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    Sample-to-sample free energy fluctuations in spin-glasses display a markedly different behaviour in finite-dimensional and fully-connected models, namely Gaussian vs. non-Gaussian. Spin-glass models defined on various types of random graphs are in an intermediate situation between these two classes of models and we investigate whether the nature of their free-energy fluctuations is Gaussian or not. It has been argued that Gaussian behaviour is present whenever the interactions are locally non-homogeneous, i.e. in most cases with the notable exception of models with fixed connectivity and random couplings Jij=±J~J_{ij}=\pm \tilde{J}. We confirm these expectation by means of various analytical results. In particular we unveil the connection between the spatial fluctuations of the populations of populations of fields defined at different sites of the lattice and the Gaussian nature of the free-energy fluctuations. On the contrary on locally homogeneous lattices the populations do not fluctuate over the sites and as a consequence the small-deviations of the free energy are non-Gaussian and scales as in the Sherrington-Kirkpatrick model

    Single Photon Signals for Warped Quantum Gravity at a Linear e+-e- Collider

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    We study the `single photon' process e+- e- -> gamma nu nubar with contributions due to exchange of massive gravitons in the Randall- Sundrum model of low-scale quantum gravity. It is shown that for significant regions in the parameter space, this process unambiguously highlights the resonance structure of the graviton sector. Even in the non-resonant part of the parameter space, we show that comparison with the benchmark process e+- e- -> mu+- mu- can clearly distinguish signals for warped gravity from similar signals for large extra dimensions.Comment: Published version; figures change

    Probabilistic Bag-Of-Hyperlinks Model for Entity Linking

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    Many fundamental problems in natural language processing rely on determining what entities appear in a given text. Commonly referenced as entity linking, this step is a fundamental component of many NLP tasks such as text understanding, automatic summarization, semantic search or machine translation. Name ambiguity, word polysemy, context dependencies and a heavy-tailed distribution of entities contribute to the complexity of this problem. We here propose a probabilistic approach that makes use of an effective graphical model to perform collective entity disambiguation. Input mentions (i.e.,~linkable token spans) are disambiguated jointly across an entire document by combining a document-level prior of entity co-occurrences with local information captured from mentions and their surrounding context. The model is based on simple sufficient statistics extracted from data, thus relying on few parameters to be learned. Our method does not require extensive feature engineering, nor an expensive training procedure. We use loopy belief propagation to perform approximate inference. The low complexity of our model makes this step sufficiently fast for real-time usage. We demonstrate the accuracy of our approach on a wide range of benchmark datasets, showing that it matches, and in many cases outperforms, existing state-of-the-art methods
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