383 research outputs found

    Contact processes with long-range interactions

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    A class of non-local contact processes is introduced and studied using mean-field approximation and numerical simulations. In these processes particles are created at a rate which decays algebraically with the distance from the nearest particle. It is found that the transition into the absorbing state is continuous and is characterized by continuously varying critical exponents. This model differs from the previously studied non-local directed percolation model, where particles are created by unrestricted Levy flights. It is motivated by recent studies of non-equilibrium wetting indicating that this type of non-local processes play a role in the unbinding transition. Other non-local processes which have been suggested to exist within the context of wetting are considered as well.Comment: Accepted with minor revisions by Journal of Statistical Mechanics: Theory and experiment

    Calculation of gluon and four-quark condensates from the operator expansion

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    The magnitudes of gluon and four-quark condensates are found from the analysis of vector mesons consisting of light quarks (the families of ρ\rho and ω\omega mesons) in the 3 loops approximation. The QCD model with infinite number of vector mesons is used to describe the function R(s)R(s). This model describes well the experimental function R(s)R(s). Polarization operators calculated with this model coincide with the Wilson operator expansion at large Q2Q^2. The improved perturbative theory, such that the polarization operators have correct analytical properties, is used. The result is <0(αs/π)G20>=0.062±0.019GeV4<0 | (\alpha_s/\pi) G^2 | 0 > = 0.062 \pm 0.019 GeV^4. The electronic widths of ρ(1450)\rho(1450) and ω(1420)\omega(1420) are calculated.Comment: 18 pages, latex, changed content slightl

    Coherent state of a nonlinear oscillator and its revival dynamics

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    The coherent state of a nonlinear oscillator having a nonlinear spectrum is constructed using Gazeau Klauder formalism. The weighting distribution and the Mandel parameter are studied. Details of the revival structure arising from different time scales underlying the quadratic energy spectrum are investigated by the phase analysis of the autocorrelation function

    Predicative Ability of QCD Sum Rules for Decuplet Baryons

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    QCD sum rules for decuplet baryon two-point functions are investigated using a comprehensive Monte-Carlo based procedure. In this procedure, all uncertainties in the QCD input parameters are incorporated simultaneously, resulting in realistic estimates of the uncertainties in the extracted phenomenological parameters. Correlations between the QCD input parameters and the phenomenological parameters are studied by way of scatter plots. The predicted couplings are useful in evaluating matrix elements of decuplet baryons in the QCD sum rule approach. They are also used to check a cubic scaling law between baryon couplings and masses, as recently found by Dey and coworkers. The results show a significant reduction in the scaling constant and some possible deviations from the cubic law.Comment: 13 pages, RevTeX, 5 PS figures embedded with psfig.st

    Second-order phase transition at the phase boundary through the FeRh first-order metamagnetic phase transition

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    The phase coexistence present through first-order phase transitions implies the presence of phase boundary walls, which can be of finite size. Better understanding of the phase boundary wall properties will provide an insight into the dynamics of first-order phase transitions. Here, by combining x-ray photon correlation spectroscopy investigations with magnetometry measurements of magnetic relaxation through the thermally activated first-order metamagnetic phase transition present in the B2-ordered FeRh alloy, we are able to isolate the dynamic behaviour of the phase boundary wall present in this system. These investigations reveal a change in the nature of the dynamic behaviour and critical scaling of the relaxation time centred around the point of maximum phase coexistence within the phase transition. All of this behaviour can be attributed to the introduction of exchange coupling across the phase boundary wall and raises questions about the role of latent heat in dynamic behaviour of this region

    Radiative cooling effects on reverse shocks formed by magnetised supersonic plasma flows

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    We study the structure of reverse shocks formed by the collision of supersonic, magnetised plasma flows driven by an inverse (or exploding) wire array with a planar conducting obstacle. We observe that the structure of these reverse shocks varies dramatically with wire material, despite the similar upstream flow velocities and mass densities. For aluminium wire arrays, the shock is sharp and well defined, consistent with magneto-hydrodynamic theory. In contrast, we do not observe a well-defined shock using tungsten wires, instead, we see a broad region dominated by density fluctuations on a wide range of spatial scales. We diagnose these two very different interactions using interferometry, Thomson scattering, shadowgraphy, and a newly developed imaging refractometer which is sensitive to small deflections of the probing laser corresponding to small-scale density perturbations. We conclude that the differences in shock structure are most likely due to radiative cooling instabilities which create small-scale density perturbations elongated along magnetic field lines in the tungsten plasma. These instabilities grow more slowly and are smoothed by thermal conduction in the aluminium plasma

    Non-Perturbative QCD Treatment of High-Energy Hadron-Hadron Scattering

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    Total cross-sections and logarithmic slopes of the elastic scattering cross-sections for different hadronic processes are calculated in the framework of the model of the stochastic vacuum. The relevant parameters of this model, a correlation length and the gluon condensate, are determined from scattering data, and found to be in very good agreement with values coming from completely different sources of information. A parameter-free relation is given between total cross-sections and slope parameters, which is shown to be remarkably valid up to the highest energies for which data exist.Comment: 60 pages, Heidelberg preprin

    High-Dose Chemotherapy and Autologous Hematopoietic Stem Cell Transplantation as Adjuvant Treatment in High-Risk Breast Cancer: Data from the European Group for Blood and Marrow Transplantation Registry.

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    The aim of this retrospective study was to assess toxicity and efficacy of adjuvant high-dose chemotherapy (HDC) and autologous hematopoietic stem cell transplantation (AHSCT) in 583 high-risk breast cancer (BC) patients (>3 positive nodes) who were transplanted between 1995 and 2005 in Europe. All patients received surgery before transplant, and 55 patients (9.5%) received neoadjuvant treatment before surgery. Median age was 47.1 years, 57.3% of patients were premenopausal at treatment, 56.5% had endocrine-responsive tumors, 19.5% had a human epidermal growth factor receptor 2 (HER2)-negative tumor, and 72.4% had ≥10 positive lymph nodes at surgery. Seventy-nine percent received a single HDC procedure. Overall transplant-related mortality was 1.9%, at .9% between 2001 and 2005, whereas secondary tumor-related mortality was .9%. With a median follow-up of 120 months, overall survival and disease-free survival rates at 5 and 10 years in the whole population were 75% and 64% and 58% and 44%, respectively. Subgroup analysis demonstrated that rates of overall survival were significantly better in patients with endocrine-responsive tumors, <10 positive lymph nodes, and smaller tumor size. HER2 status did not affect survival probability. Adjuvant HDC with AHSCT has a low mortality rate and provides impressive long-term survival rates in patients with high-risk BC. Our results suggest that this treatment modality should be considered in selected high-risk BC patients and further investigated in clinical trials
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