13,937 research outputs found

    Scaled Brownian motion: a paradoxical process with a time dependent diffusivity for the description of anomalous diffusion

    Full text link
    Anomalous diffusion is frequently described by scaled Brownian motion (SBM), a Gaussian process with a power-law time dependent diffusion coefficient. Its mean squared displacement is x2(t)K(t)t\langle x^2(t)\rangle\simeq\mathscr{K}(t)t with K(t)tα1\mathscr{K}(t)\simeq t^{\alpha-1} for 0<α<20<\alpha<2. SBM may provide a seemingly adequate description in the case of unbounded diffusion, for which its probability density function coincides with that of fractional Brownian motion. Here we show that free SBM is weakly non-ergodic but does not exhibit a significant amplitude scatter of the time averaged mean squared displacement. More severely, we demonstrate that under confinement, the dynamics encoded by SBM is fundamentally different from both fractional Brownian motion and continuous time random walks. SBM is highly non-stationary and cannot provide a physical description for particles in a thermalised stationary system. Our findings have direct impact on the modelling of single particle tracking experiments, in particular, under confinement inside cellular compartments or when optical tweezers tracking methods are used.Comment: 7 pages, 5 figure

    Formulating the Net Gain of MISO-SFN in the Presence of Self-Interferences

    Get PDF
    In this study, an analytical formula for multiple-input single-output single frequency network gain (MISO-SFNG) is investigated. To formulate the net MISO-SFNG, we derived the average signal to interference plus noise ratio (SINR) where the gain achieved by the distributed MISO diversity as a function of power imbalance is curve-fitted. Further, we analyzed the losses owing to self-interferences resulting from the delay spread and imperfect channel estimation. We verified the accuracy and effectiveness of the derived formula by comparing the measurement results with the analytical results. The derived formula helps to understand how various system factors affect the gain under a given condition. The formula can be used to evaluate the MISO-SFNG and to predict the MISO-SFN coverage in various system configurations

    Synthesizing framework models for symbolic execution

    Get PDF
    Symbolic execution is a powerful program analysis technique, but it is difficult to apply to programs built using frameworks such as Swing and Android, because the framework code itself is hard to symbolically execute. The standard solution is to manually create a framework model that can be symbolically executed, but developing and maintaining a model is difficult and error-prone. In this paper, we present Pasket, a new system that takes a first step toward automatically generating Java framework models to support symbolic execution. Pasket's focus is on creating models by instantiating design patterns. Pasket takes as input class, method, and type information from the framework API, together with tutorial programs that exercise the framework. From these artifacts and Pasket's internal knowledge of design patterns, Pasket synthesizes a framework model whose behavior on the tutorial programs matches that of the original framework. We evaluated Pasket by synthesizing models for subsets of Swing and Android. Our results show that the models derived by Pasket are sufficient to allow us to use off-the-shelf symbolic execution tools to analyze Java programs that rely on frameworks.National Science Foundation (U.S.) (CCF-1139021)National Science Foundation (U.S.) (CCF-1139056)National Science Foundation (U.S.) (CCF-1161775

    Neutron and muon-induced background studies for the AMoRE double-beta decay experiment

    Full text link
    AMoRE (Advanced Mo-based Rare process Experiment) is an experiment to search a neutrinoless double-beta decay of 100^{100}Mo in molybdate crystals. The neutron and muon-induced backgrounds are crucial to obtain the zero-background level (<10510^{-5} counts/(keV\cdotkg\cdotyr)) for the AMoRE-II experiment, which is the second phase of the AMoRE project, planned to run at YEMI underground laboratory. To evaluate the effects of neutron and muon-induced backgrounds, we performed Geant4 Monte Carlo simulations and studied a shielding strategy for the AMORE-II experiment. Neutron-induced backgrounds were also included in the study. In this paper, we estimated the background level in the presence of possible shielding structures, which meet the background requirement for the AMoRE-II experiment

    Anomalous Multiplicity Fluctuations from Phase Transitions in Heavy Ion Collisions

    Full text link
    Event-by-event fluctuations and correlations between particles produced in relativistic nuclear collisions are studied. The fluctuations in positive, negative, total and net charge are closely related through correlations. In the event of a phase transitions to a quark-gluon plasma, fluctuations in total and net charge can be enhanced and reduced respectively which, however, is very sensitive to the acceptance and centrality. If the colliding system experiences strong density fluctuations due, e.g., to droplet formation in a first-order phase transition, all fluctuations can be enhanced substantially. The importance of fluctuations and correlations is exemplified by event-by-event measurement of the multiplicities of J/ΨJ/\Psi's and charged particles since these observables should anti-correlate in the presence of co-mover or anomalous absorption.Comment: revised version to appear in Phys. Rev. C, 5 page

    Full Length Research Paper Lack of correlation between H2O2 production and in vitro anti-staphyloccocal activity of vaginal Lactobacillus spp.

    Get PDF
    Lactobacilli are considered to play important roles in human health as they are known to secrete inhibitory substances to prevent infection by pathogenic organisms. Previously we have isolated 77 strains of Lactobacillus spp. from human vaginas. In this study, using the plate diffusion method, strains showing in vitro antagonistic activity against pathogenic Staphylococcus aureus were screened. Because Lactobacillus spp. are known to produce hydrogen peroxide (H2O2) as an antimicrobialsubstance, we attempted to determine if there is a consistent link between in vitro anti-staphylococcal activity and H2O2 production by Lactobacillus spp. A simple quantitative analysis of H2O2 produced by Lactobacillus spp. was performed by a modified spectrophotometric method. A statistically significant correlation was not found between in vitro anti-staphylococcal activity and H2O2 production

    Production and optical properties of liquid scintillator for the JSNS2^{2} experiment

    Full text link
    The JSNS2^{2} (J-PARC Sterile Neutrino Search at J-PARC Spallation Neutron Source) experiment will search for neutrino oscillations over a 24 m short baseline at J-PARC. The JSNS2^{2} inner detector will be filled with 17 tons of gadolinium-loaded liquid scintillator (LS) with an additional 31 tons of unloaded LS in the intermediate γ\gamma-catcher and outer veto volumes. JSNS2^{2} has chosen Linear Alkyl Benzene (LAB) as an organic solvent because of its chemical properties. The unloaded LS was produced at a refurbished facility, originally used for scintillator production by the RENO experiment. JSNS2^{2} plans to use ISO tanks for the storage and transportation of the LS. In this paper, we describe the LS production, and present measurements of its optical properties and long term stability. Our measurements show that storing the LS in ISO tanks does not result in degradation of its optical properties.Comment: 7 pages, 4 figures
    corecore