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https://www.readbyqxmd.com/read/28674453/on-noise-resolution-uncertainty-in-quantum-field-theory
#1
Timur E Gureyev, Alexander Kozlov, Yakov I Nesterets, David M Paganin, Harry M Quiney
An uncertainty inequality is presented that establishes a lower limit for the product of the variance of the time-averaged intensity of a mode of a quantized electromagnetic field and the degree of its spatial localization. The lower limit is determined by the vacuum fluctuations within the volume corresponding to the width of the mode. This result also leads to a generalized form of the Heisenberg uncertainty principle for boson fields in which the lower limit for the product of uncertainties in the spatial and momentum localization of a mode is equal to the product of Planck's constant and a dimensionless functional which reflects the joint signal-to-noise ratio of the position and momentum of vacuum fluctuations in the region of the phase space occupied by the mode...
July 3, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28618562/evolution-of-moments-and-correlations-in-nonrenewal-escape-time-processes
#2
Wilhelm Braun, Rüdiger Thul, André Longtin
The theoretical description of nonrenewal stochastic systems is a challenge. Analytical results are often not available or can be obtained only under strong conditions, limiting their applicability. Also, numerical results have mostly been obtained by ad hoc Monte Carlo simulations, which are usually computationally expensive when a high degree of accuracy is needed. To gain quantitative insight into these systems under general conditions, we here introduce a numerical iterated first-passage time approach based on solving the time-dependent Fokker-Planck equation (FPE) to describe the statistics of nonrenewal stochastic systems...
May 2017: Physical Review. E
https://www.readbyqxmd.com/read/28589413/single-particle-brownian-motion-with-solid-friction
#3
Prasenjit Das, Sanjay Puri, Moshe Schwartz
We study the Brownian dynamics of a solid particle on a vibrating solid surface. Phenomenologically, the interaction between the two solid surfaces is modeled by solid friction, and the Gaussian white noise models the vibration of the solid surface. The solid friction force is proportional to the sign of relative velocity. We derive the Fokker-Planck (FP) equation for the time-dependent probability distribution to find the particle at a given location. We calculate analytically the steady state velocity distribution function, mean-square velocity and diffusion coefficient in d-dimensions...
June 2017: European Physical Journal. E, Soft Matter
https://www.readbyqxmd.com/read/28571349/asymmetric-osmotic-water-permeation-through-a-vesicle-membrane
#4
Jiaye Su, Yunzhen Zhao, Chang Fang, Yue Shi
Understanding the water permeation through a cell membrane is of primary importance for biological activities and a key step to capture its shape transformation in salt solution. In this work, we reveal the dynamical behaviors of osmotically driven transport of water molecules across a vesicle membrane by molecular dynamics simulations. Of particular interest is that the water transport in and out of vesicles is highly distinguishable given the osmotic force are the same, suggesting an asymmetric osmotic transportation...
May 28, 2017: Journal of Chemical Physics
https://www.readbyqxmd.com/read/28484333/robust-identification-of-harmonic-oscillator-parameters-using-the-adjoint-fokker-planck-equation
#5
E Boujo, N Noiray
We present a model-based output-only method for identifying from time series the parameters governing the dynamics of stochastically forced oscillators. In this context, suitable models of the oscillator's damping and stiffness properties are postulated, guided by physical understanding of the oscillatory phenomena. The temporal dynamics and the probability density function of the oscillation amplitude are described by a Langevin equation and its associated Fokker-Planck equation, respectively. One method consists in fitting the postulated analytical drift and diffusion coefficients with their estimated values, obtained from data processing by taking the short-time limit of the first two transition moments...
April 2017: Proceedings. Mathematical, Physical, and Engineering Sciences
https://www.readbyqxmd.com/read/28476429/-hospitalization-in-french-forensic-units-results-of-a-patient-satisfaction-survey
#6
D de Labrouhe, L Plancke, A Amad, C-L Charrel, D Touitou, M Bodon-Bruzel, P Thomas, T Fovet
BACKGROUND: In France, special full-time inpatient hospital units (UHSA) have been created for inmates with psychiatric disorders. Since they were established in 2010, the quality of care in such units has not been studied. Particularly, no patient satisfaction survey has been conducted yet. The main objective of this study was to assess the patients' satisfaction about their hospitalization in UHSA. METHODS: A descriptive study has been performed in two hospitals (UHSA of Villejuif and UHSA of Lille-Seclin)...
May 2, 2017: Revue D'épidémiologie et de Santé Publique
https://www.readbyqxmd.com/read/28435034/cytoreductive-prostatectomy-for-metastatic-prostate-cancer-first-lessons-learned-from-the-multicentric-prospective-local-treatment-of-metastatic-prostate-cancer-lomp-trial
#7
Filip Poelaert, Caroline Verbaeys, Bernard Rappe, Bart Kimpe, Ignace Billiet, Hendrik Plancke, Karel Decaestecker, Valérie Fonteyne, Sarah Buelens, Nicolaas Lumen
OBJECTIVE: To prospectively evaluate patients with newly diagnosed metastatic prostate cancer in the context of the LoMP trial (which investigates the role of cytoreductive radical prostatectomy [cRP] in addition to standard of care [SoC]) and to provide a preliminary analysis of patient's characteristics, safety of cRP, and early local symptoms. PATIENTS AND METHODS: cRP was performed in asymptomatic patients with a resectable tumor and who were fit to undergo surgery (group A, n = 17)...
August 2017: Urology
https://www.readbyqxmd.com/read/28429787/heat-temperature-and-clausius-inequality-in-a-model-for-active-brownian-particles
#8
Umberto Marini Bettolo Marconi, Andrea Puglisi, Claudio Maggi
Methods of stochastic thermodynamics and hydrodynamics are applied to a recently introduced model of active particles. The model consists of an overdamped particle subject to Gaussian coloured noise. Inspired by stochastic thermodynamics, we derive from the system's Fokker-Planck equation the average exchanges of heat and work with the active bath and the associated entropy production. We show that a Clausius inequality holds, with the local (non-uniform) temperature of the active bath replacing the uniform temperature usually encountered in equilibrium systems...
April 21, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28415284/theory-of-linear-sweep-voltammetry-with-diffuse-charge-unsupported-electrolytes-thin-films-and-leaky-membranes
#9
David Yan, Martin Z Bazant, P M Biesheuvel, Mary C Pugh, Francis P Dawson
Linear sweep and cyclic voltammetry techniques are important tools for electrochemists and have a variety of applications in engineering. Voltammetry has classically been treated with the Randles-Sevcik equation, which assumes an electroneutral supported electrolyte. In this paper, we provide a comprehensive mathematical theory of voltammetry in electrochemical cells with unsupported electrolytes and for other situations where diffuse charge effects play a role, and present analytical and simulated solutions of the time-dependent Poisson-Nernst-Planck equations with generalized Frumkin-Butler-Volmer boundary conditions for a 1:1 electrolyte and a simple reaction...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28415177/influence-of-atomic-kinetics-in-the-simulation-of-plasma-microscopic-properties-and-thermal-instabilities-for-radiative-bow-shock-experiments
#10
G Espinosa, R Rodríguez, J M Gil, F Suzuki-Vidal, S V Lebedev, A Ciardi, J G Rubiano, P Martel
Numerical simulations of laboratory astrophysics experiments on plasma flows require plasma microscopic properties that are obtained by means of an atomic kinetic model. This fact implies a careful choice of the most suitable model for the experiment under analysis. Otherwise, the calculations could lead to inaccurate results and inappropriate conclusions. First, a study of the validity of the local thermodynamic equilibrium in the calculation of the average ionization, mean radiative properties, and cooling times of argon plasmas in a range of plasma conditions of interest in laboratory astrophysics experiments on radiative shocks is performed in this work...
March 2017: Physical Review. E
https://www.readbyqxmd.com/read/28333590/mean-first-passage-memory-lifetimes-by-reducing-complex-synapses-to-simple-synapses
#11
Terry Elliott
Memory models that store new memories by forgetting old ones have memory lifetimes that are rather short and grow only logarithmically in the number of synapses. Attempts to overcome these deficits include "complex" models of synaptic plasticity in which synapses possess internal states governing the expression of synaptic plasticity. Integrate-and-express, filter-based models of synaptic plasticity propose that synapses act as low-pass filters, integrating plasticity induction signals before expressing synaptic plasticity...
March 23, 2017: Neural Computation
https://www.readbyqxmd.com/read/28325129/lobectomy-for-non-small-cell-lung-carcinoma-a-nationwide-study-of-short-and-long-term-survival
#12
G N Oskarsdottir, H Halldorsson, M I Sigurdsson, B M Fridriksson, K Baldvinsson, A W Orrason, S Jonsson, M Planck, T Gudbjartsson
INTRODUCTION: Lobectomy is the standard curative treatment for non-small cell carcinoma (NSCLC) of the lung. Most studies on lobectomy have focused on short-term outcome and 30-day mortality. The aim of this study was to determine both short-term and long-term surgical outcome in all patients who underwent lobectomy for NSCLC in Iceland over a 24-year period. MATERIAL AND METHODS: The study involved 489 consecutive patients with NSCLC who underwent lobectomy with curative intent in Iceland, 1991-2014...
March 21, 2017: Acta Oncologica
https://www.readbyqxmd.com/read/28306551/master-equations-and-the-theory-of-stochastic-path-integrals
#13
Markus F Weber, Erwin Frey
This review provides a pedagogic and self-contained introduction to master equations and to their representation by path integrals. Since the 1930s, master equations have served as a fundamental tool to understand the role of fluctuations in complex biological, chemical, and physical systems. Despite their simple appearance, analyses of master equations most often rely on low-noise approximations such as the Kramers-Moyal or the system size expansion, or require ad-hoc closure schemes for the derivation of low-order moment equations...
April 2017: Reports on Progress in Physics
https://www.readbyqxmd.com/read/28297849/continuous-time-limits-of-the-utterance-selection-model
#14
Jérôme Michaud
In this paper we derive alternative continuous time limits of the utterance selection model (USM) for language change [G. J. Baxter et al., Phys. Rev. E 73, 046118 (2006)PLEEE81539-375510.1103/PhysRevE.73.046118]. This is motivated by the fact that the Fokker-Planck continuous time limit derived in the original version of the USM is only valid for a small range of parameters. We investigate the consequences of relaxing these constraints on parameters. Using the normal approximation of the multinomial approximation, we derive a continuous time limit of the USM in the form of a weak-noise stochastic differential equation...
February 2017: Physical Review. E
https://www.readbyqxmd.com/read/28243720/extracting-cellular-automaton-rules-from-physical-langevin-equation-models-for-single-and-collective-cell-migration
#15
J M Nava-Sedeño, H Hatzikirou, F Peruani, A Deutsch
Cellular automata (CA) are discrete time, space, and state models which are extensively used for modeling biological phenomena. CA are "on-lattice" models with low computational demands. In particular, lattice-gas cellular automata (LGCA) have been introduced as models of single and collective cell migration. The interaction rule dictates the behavior of a cellular automaton model and is critical to the model's biological relevance. The LGCA model's interaction rule has been typically chosen phenomenologically...
February 27, 2017: Journal of Mathematical Biology
https://www.readbyqxmd.com/read/28208407/stochastically-gated-local-and-occupation-times-of-a-brownian-particle
#16
Paul C Bressloff
We generalize the Feynman-Kac formula to analyze the local and occupation times of a Brownian particle moving in a stochastically gated one-dimensional domain. (i) The gated local time is defined as the amount of time spent by the particle in the neighborhood of a point in space where there is some target that only receives resources from (or detects) the particle when the gate is open; the target does not interfere with the motion of the Brownian particle. (ii) The gated occupation time is defined as the amount of time spent by the particle in the positive half of the real line, given that it can only cross the origin when a gate placed at the origin is open; in the closed state the particle is reflected...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28208350/l%C3%A3-vy-flights-in-the-presence-of-a-point-sink-of-finite-strength
#17
Deepika Janakiraman
In this paper, the absorption of a particle undergoing Lévy flight in the presence of a point sink of arbitrary strength and position is studied. The motion of such a particle is given by a modified Fokker-Planck equation whose exact solution in the Laplace domain can be described in terms of the Laplace transform of the unperturbed (absence of the sink) Green's function. This solution for the Green's function is a well-studied, generic result which applies to both fractional and usual Fokker-Planck equations alike...
January 2017: Physical Review. E
https://www.readbyqxmd.com/read/28157360/redefining-the-axion-window
#18
Luca Di Luzio, Federico Mescia, Enrico Nardi
A major goal of axion searches is to reach inside the parameter space region of realistic axion models. Currently, the boundaries of this region depend on somewhat arbitrary criteria, and it would be desirable to specify them in terms of precise phenomenological requirements. We consider hadronic axion models and classify the representations R_{Q} of the new heavy quarks Q. By requiring that (i) the Q's are sufficiently short lived to avoid issues with long-lived strongly interacting relics, (ii) no Landau poles are induced below the Planck scale; 15 cases are selected which define a phenomenologically preferred axion window bounded by a maximum (minimum) value of the axion-photon coupling about 2 times (4 times) larger than is commonly assumed...
January 20, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28157343/critical-number-of-fields-in-stochastic-inflation
#19
Vincent Vennin, Hooshyar Assadullahi, Hassan Firouzjahi, Mahdiyar Noorbala, David Wands
Stochastic effects in generic scenarios of inflation with multiple fields are investigated. First passage time techniques are employed to calculate the statistical moments of the number of inflationary e-folds, which give rise to all correlation functions of primordial curvature perturbations through the stochastic δN formalism. The number of fields is a critical parameter. The probability of exploring arbitrarily large-field regions of the potential becomes nonvanishing when more than two fields are driving inflation...
January 20, 2017: Physical Review Letters
https://www.readbyqxmd.com/read/28089383/-long-term-psychiatric-hospitalizations
#20
L Plancke, A Amariei
BACKGROUND: Long-term hospitalizations in psychiatry raise the question of desocialisation of the patients and the inherent costs. METHODS: Individual indicators were extracted from a medical administrative database containing full-time psychiatric hospitalizations for the period 2011-2013 of people over 16 years old living in the French region of Nord-Pas-de-Calais. We calculated the proportion of people who had experienced a hospitalization with a duration of 292 days or more during the study period...
February 2017: Revue D'épidémiologie et de Santé Publique
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