189 research outputs found

    A limit result for a system of particles in random environment

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    We consider an infinite system of particles in one dimension, each particle performs independant Sinai's random walk in random environment. Considering an instant tt, large enough, we prove a result in probability showing that the particles are trapped in the neighborhood of well defined points of the lattice depending on the random environment the time tt and the starting point of the particles.Comment: 11 page

    Non-equilibrium phase transitions in one-dimensional kinetic Ising models

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    A family of nonequilibrium kinetic Ising models, introduced earlier, evolving under the competing effect of spin flips at {\it zero temperature} and nearest neighbour random spin exchanges is further investigated here. By increasing the range of spin exchanges and/or their strength the nature of the phase transition 'Ising-to-active' becomes of (dynamic) mean-field type and a first order tricitical point is located at the Glauber (δ=0\delta=0) limit. Corrections to mean-field theory are evaluated up to sixth order in a cluster approximation and found to give good results concerning the phase boundary and the critical exponent β\beta of the order parameter which is obtained as β1.0\beta\simeq1.0.Comment: 15 pages, revtex file, figures available at request from [email protected] in postscript format, submitted to J.Phys.

    Anomalous tag diffusion in the asymmetric exclusion model with particles of arbitrary sizes

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    Anomalous behavior of correlation functions of tagged particles are studied in generalizations of the one dimensional asymmetric exclusion problem. In these generalized models the range of the hard-core interactions are changed and the restriction of relative ordering of the particles is partially brocken. The models probing these effects are those of biased diffusion of particles having size S=0,1,2,..., or an effective negative "size" S=-1,-2,..., in units of lattice space. Our numerical simulations show that irrespective of the range of the hard-core potential, as long some relative ordering of particles are kept, we find suitable sliding-tag correlation functions whose fluctuations growth with time anomalously slow (t1/3t^{{1/3}}), when compared with the normal diffusive behavior (t1/2t^{{1/2}}). These results indicate that the critical behavior of these stochastic models are in the Kardar-Parisi-Zhang (KPZ) universality class. Moreover a previous Bethe-ansatz calculation of the dynamical critical exponent zz, for size S0S \geq 0 particles is extended to the case S<0S<0 and the KPZ result z=3/2z=3/2 is predicted for all values of SZS \in {Z}.Comment: 4 pages, 3 figure

    Nature of the band gap of In2O3 revealed by first-principles calculations and x-ray spectroscopy

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    Bulk and surface sensitive x-ray spectroscopic techniques are applied in tandem to show that the valence band edge for In2O3 is found significantly closer to the bottom of the conduction band than expected on the basis of the widely quoted bulk band gap of 3.75 eV. First-principles theory shows that the upper valence bands of In2O3 exhibit a small dispersion and the conduction band minimum is positioned at Gamma. However, direct optical transitions give a minimal dipole intensity until 0.8 eV below the valence band maximum. The results set an upper limit on the fundamental band gap of 2.9 eV

    Exact Tagged Particle Correlations in the Random Average Process

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    We study analytically the correlations between the positions of tagged particles in the random average process, an interacting particle system in one dimension. We show that in the steady state the mean squared auto-fluctuation of a tracer particle grows subdiffusively as sigma2(t) t1/2sigma^2(t) ~ t^{1/2} for large time t in the absence of external bias, but grows diffusively sigma2(t) tsigma^2(t) ~ t in the presence of a nonzero bias. The prefactors of the subdiffusive and diffusive growths as well as the universal scaling function describing the crossover between them are computed exactly. We also compute sigmar2(t)sigma_r^2(t), the mean squared fluctuation in the position difference of two tagged particles separated by a fixed tag shift r in the steady state and show that the external bias has a dramatic effect in the time dependence of sigmar2(t)sigma_r^2(t). For fixed r, sigmar2(t)sigma_r^2(t) increases monotonically with t in absence of bias but has a non-monotonic dependence on t in presence of bias. Similarities and differences with the simple exclusion process are also discussed.Comment: 10 pages, 2 figures, revte

    Safety and on-treatment efficacy of telaprevir: the early access programme for patients with advanced hepatitis C

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    Background and aim Severe adverse events (AEs) compromise the outcome of direct antiviral agent-based treatment in patients with advanced liver fibrosis due to HCV infection. HEP3002 is an ongoing multinational programme to evaluate safety and efficacy of telaprevir (TVR) plus pegylated-interferon-alpha (PEG-IFN alpha) and ribavirin (RBV) in patients with advanced liver fibrosis caused by HCV genotype 1 (HCV-1).Methods 1782 patients with HCV-1 and bridging fibrosis or compensated cirrhosis were prospectively recruited from 16 countries worldwide, and treated with 12 weeks of TVR plus PEG-IFN/RBV, followed by 12 or 36 weeks of PEG-IFN and RBV (PR) alone dependent on virological response to treatment and previous response type.Results 1587 patients completed 12 weeks of triple therapy and 4 weeks of PR tail (53% cirrhosis, 22% HCV-1a). By week 12, HCV RNA was undetectable in 85% of naives, 88% of relapsers, 80% of partial responders and 72% of null responders. Overall, 931 patients (59%) developed grade 1-4 anaemia (grade 3/4 in 31%), 630 (40%) dose reduced RBV, 332 (21%) received erythropoietin and 157 (10%) were transfused. Age and female gender were the strongest predictors of anaemia. 64 patients (4%) developed a grade 3/4 rash. Discontinuation of TVR due to AEs was necessary in 193 patients (12%). Seven patients died (0.4%, six had cirrhosis).Conclusions in compensated patients with advanced fibrosis due to HCV-1, triple therapy with TVR led to satisfactory rates of safety, tolerability and on-treatment virological response with adequate managements of AEs.Janssen PharmaceuticsUniv Milan, Div Gastroenterol, Dept Med, Fdn IRCCS Ca Granda Osped Maggiore Policlin, Milan, ItalyHosp Univ 12 Octubre, Secc Aparato Digest, Madrid, SpainIM Sechenov First Moscow State Med Univ, EM Tareev Clin Nephrol Internal & Occupat Med, Moscow, RussiaUniversidade Federal de São Paulo, Viral Hepatitis Div Infect Dis, Outpatient Clin HIV, São Paulo, BrazilUniv Sydney, Royal Prince Alfred Hosp, AW Morrow Gastroenterol & Liver Ctr, Sydney, NSW 2006, AustraliaCharles Univ Prague, Fac Med 1, Dept Internal Med, Prague, Czech RepublicCent Mil Hosp Prague, Prague, Czech RepublicUniv Libre Brussels, Dept Gastroenterol Hepatopancreatol & Digest Onco, Erasme Univ Hosp, Liver Unit, Brussels, BelgiumCarol Davila Univ Med & Pharm, Natl Inst Infect Dis, Bucharest, RomaniaJanssen Pharmaceut, B-2340 Beerse, BelgiumJanssen Pharmaceut, Paris, FranceJanssen Res & Dev, Titusville, NJ USAJanssen Res & Dev, High Wycombe, Bucks, EnglandJanssen Cilag AG, Zug, SwitzerlandHannover Med Sch, D-30623 Hannover, GermanyUniversidade Federal de São Paulo, Viral Hepatitis Div Infect Dis, Outpatient Clin HIV, São Paulo, BrazilWeb of Scienc

    Non equilibrium steady states: fluctuations and large deviations of the density and of the current

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    These lecture notes give a short review of methods such as the matrix ansatz, the additivity principle or the macroscopic fluctuation theory, developed recently in the theory of non-equilibrium phenomena. They show how these methods allow to calculate the fluctuations and large deviations of the density and of the current in non-equilibrium steady states of systems like exclusion processes. The properties of these fluctuations and large deviation functions in non-equilibrium steady states (for example non-Gaussian fluctuations of density or non-convexity of the large deviation function which generalizes the notion of free energy) are compared with those of systems at equilibrium.Comment: 35 pages, 9 figure

    Chronic Hepatitis C Treatment in Patients with Drug Injection History: Findings of the INTEGRATE Prospective, Observational Study.

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    INTRODUCTION: People who inject drugs represent an under-treated chronic hepatitis C virus (HCV)-infected patient population. METHODS: INTEGRATE was a prospective, observational study investigating the effectiveness, safety, and adherence in routine clinical practice to telaprevir in combination with peg-interferon and ribavirin (Peg-IFN/RBV) in patients with history of injecting drug use chronically infected with genotype 1 HCV. RESULTS: A total of 46 patients were enrolled and included in the intent-to-treat (ITT) population. Among heroin and/or cocaine users (n = 37; 80%), 22% reported use in the past month; 74% (34/46) of patients were on opioid substitution therapy in the pre-treatment phase, and 43% (20/46) discontinued HCV treatment prematurely. Sustained virologic response rate was 54% (25/46) in the ITT population and 74% (25/34) in the per protocol (evaluable-for-effectiveness) population. The main reason for failure in the ITT analysis was loss to follow-up (n = 8; 17%). Adverse events occurred in 91% (42/46) of patients. Mean patient-reported adherence to study drugs was >89% at Week 4, Week 12 and end of treatment. CONCLUSION: Despite a high rate of treatment discontinuation (including loss to follow-up), self-reported adherence to treatment was good and virologic cure rates were similar to those reported in large real-world cohorts. Our findings suggest that people with a history of injecting drug use should be considered for treatment of chronic HCV infection, and highlight the need for improvements in patient support to boost retention in care and, in turn, help to prevent reinfection and transmission. CLINICAL TRIAL REGISTRATION: Clinicaltrials.gov identifier, NCT01980290. FUNDING: Janssen Pharmaceuticals

    A pedestrian's view on interacting particle systems, KPZ universality, and random matrices

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    These notes are based on lectures delivered by the authors at a Langeoog seminar of SFB/TR12 "Symmetries and universality in mesoscopic systems" to a mixed audience of mathematicians and theoretical physicists. After a brief outline of the basic physical concepts of equilibrium and nonequilibrium states, the one-dimensional simple exclusion process is introduced as a paradigmatic nonequilibrium interacting particle system. The stationary measure on the ring is derived and the idea of the hydrodynamic limit is sketched. We then introduce the phenomenological Kardar-Parisi-Zhang (KPZ) equation and explain the associated universality conjecture for surface fluctuations in growth models. This is followed by a detailed exposition of a seminal paper of Johansson that relates the current fluctuations of the totally asymmetric simple exclusion process (TASEP) to the Tracy-Widom distribution of random matrix theory. The implications of this result are discussed within the framework of the KPZ conjecture.Comment: 52 pages, 4 figures; to appear in J. Phys. A: Math. Theo
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