14,524 research outputs found
Scaled Brownian motion: a paradoxical process with a time dependent diffusivity for the description of anomalous diffusion
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 with
for . 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
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
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
AMoRE (Advanced Mo-based Rare process Experiment) is an experiment to search
a neutrinoless double-beta decay of Mo in molybdate crystals. The
neutron and muon-induced backgrounds are crucial to obtain the zero-background
level (< counts/(keVkgyr)) 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
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 '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.
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 JSNS experiment
The JSNS (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 JSNS 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 -catcher and outer veto volumes.
JSNS 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.
JSNS 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
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