2,090 research outputs found
Stochastic thermodynamics for Ising chain and symmetric exclusion process
We verify the finite time fluctuation theorem for a linear Ising chain at its
ends in contact with heat reservoirs. Analytic results are derived for a chain
consisting of only two spins. The system can be mapped onto a model for
particle transport, namely the symmetric exclusion process, in contact with
thermal and particle reservoirs. We modify the symmetric exclusion process to
represent a thermal engine and reproduce universal features of the efficiency
at maximum power
Effects of internal fluctuations on the spreading of Hantavirus
We study the spread of Hantavirus over a host population of deer mice using a
population dynamics model. We show that taking into account the internal
fluctuations in the mouse population due to its discrete character strongly
alters the behaviour of the system. In addition to the familiar transition
present in the deterministic model, the inclusion of internal fluctuations
leads to the emergence of an additional deterministically hidden transition. We
determine parameter values that lead to maximal propagation of the disease, and
discuss some implications for disease prevention policies
Thermoelectric efficiency at maximum power in a quantum dot
We identify the operational conditions for maximum power of a
nanothermoelectric engine consisting of a single quantum level embedded between
two leads at different temperatures and chemical potentials. The corresponding
thermodynamic efficiency agrees with the Curzon-Ahlborn expression up to
quadratic terms in the gradients, supporting the thesis of universality beyond
linear response.Comment: 4 pages, 3 figure
Bullying and Victimization in Elementary Schools: A Comparison of Bullies, Victims, Bully/Victims, and Uninvolved Preadolescents
Research on bullying and victimization largely rests on univariate analyses and on reports from a single informant. Researchers may thus know too little about the simultaneous effects of various independent and dependent variables, and their research may be biased by shared method variance. The database for
this Dutch study was large (N = 1,065) and rich enough to allow multivariate analysis and multisource information. In addition, the effect of familial vulnerability for internalizing and externalizing disorders was studied. Gender, aggressiveness, isolation, and dislikability were most strongly related to bullying and victimization. Among the many findings that deviated from or enhanced the univariate knowledge
base were that not only victims and bully/victims but bullies as well were disliked and that parenting was unrelated to bullying and victimization once other factors were controlled.
Continuous and discontinuous phase transitions and partial synchronization in stochastic three-state oscillators
We investigate both continuous (second-order) and discontinuous (first-order)
transitions to macroscopic synchronization within a single class of discrete,
stochastic (globally) phase-coupled oscillators. We provide analytical and
numerical evidence that the continuity of the transition depends on the
coupling coefficients and, in some nonuniform populations, on the degree of
quenched disorder. Hence, in a relatively simple setting this class of models
exhibits the qualitative behaviors characteristic of a variety of considerably
more complicated models. In addition, we study the microscopic basis of
synchronization above threshold and detail the counterintuitive subtleties
relating measurements of time averaged frequencies and mean field oscillations.
Most notably, we observe a state of suprathreshold partial synchronization in
which time-averaged frequency measurements from individual oscillators do not
correspond to the frequency of macroscopic oscillations observed in the
population
Comprehensive study of phase transitions in relaxational systems with field-dependent coefficients
We present a comprehensive study of phase transitions in single-field systems
that relax to a non-equilibrium global steady state. The mechanism we focus on
is not the so-called Stratonovich drift combined with collective effects, but
is instead similar to the one associated with noise-induced transitions a la
Horsthemke-Lefever in zero-dimensional systems. As a consequence, the noise
interpretation (e.g., Ito vs Stratonvich) merely shifts the phase boundaries.
With the help of a mean-field approximation, we present a broad qualitative
picture of the various phase diagrams that can be found in these systems. To
complement the theoretical analysis we present numerical simulations that
confirm the findings of the mean-field theory
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