2,727 research outputs found
On the work distribution for the adiabatic compression of a dilute classical gas
We consider the adiabatic and quasi-static compression of a dilute classical
gas, confined in a piston and initially equilibrated with a heat bath. We find
that the work performed during this process is described statistically by a
gamma distribution. We use this result to show that the model satisfies the
non-equilibrium work and fluctuation theorems, but not the
flucutation-dissipation relation. We discuss the rare but dominant realizations
that contribute most to the exponential average of the work, and relate our
results to potentially universal work distributions.Comment: 4 page
Effects of Diversity on Multi-agent Systems: Minority Games
We consider a version of large population games whose agents compete for
resources using strategies with adaptable preferences. The games can be used to
model economic markets, ecosystems or distributed control. Diversity of initial
preferences of strategies is introduced by randomly assigning biases to the
strategies of different agents. We find that diversity among the agents reduces
their maladaptive behavior. We find interesting scaling relations with
diversity for the variance and other parameters such as the convergence time,
the fraction of fickle agents, and the variance of wealth, illustrating their
dynamical origin. When diversity increases, the scaling dynamics is modified by
kinetic sampling and waiting effects. Analyses yield excellent agreement with
simulations.Comment: 41 pages, 16 figures; minor improvements in content, added
references; to be published in Physical Review
Higher-order Kerr terms allow ionization-free filamentation in gases
We show that higher-order nonlinear indices (, , , )
provide the main defocusing contribution to self-channeling of ultrashort laser
pulses in air and Argon at 800 nm, in contrast with the previously accepted
mechanism of filamentation where plasma was considered as the dominant
defocusing process. Their consideration allows to reproduce experimentally
observed intensities and plasma densities in self-guided filaments.Comment: 11 pages, 6 figures (11 panels
Minimal Work Principle and its Limits for Classical Systems
The minimal work principle asserts that work done on a thermally isolated
equilibrium system, is minimal for the slowest (adiabatic) realization of a
given process. This principle, one of the formulations of the second law, is
operationally well-defined for any finite (few particle) Hamiltonian system.
Within classical Hamiltonian mechanics, we show that the principle is valid for
a system of which the observable of work is an ergodic function. For
non-ergodic systems the principle may or may not hold, depending on additional
conditions. Examples displaying the limits of the principle are presented and
their direct experimental realizations are discussed.Comment: 4 + epsilon pages, 1 figure, revte
Spectral dependence of purely-Kerr driven filamentation in air and argon
Based on numerical simulations, we show that higher-order nonlinear indices
(up to and , respectively) of air and argon have a dominant
contribution to both focusing and defocusing in the self-guiding of ultrashort
laser pulses over most of the spectrum. Plasma generation and filamentation are
therefore decoupled. As a consequence, ultraviolet wavelength may not be the
optimal wavelengths for applications requiring to maximize ionization.Comment: 14 pages, 4 figures (14 panels
From higher-order Kerr nonlinearities to quantitative modeling of 3rd and 5th harmonic generation in argon
The recent measurement of negative higher-order Kerr effect (HOKE) terms in
gases has given rise to a controversial debate, fed by its impact on short
laser pulse propagation. By comparing the experimentally measured yield of the
third and fifth harmonics, with both an analytical and a full comprehensive
numerical propagation model, we confirm the absolute and relative values of the
reported HOKE indices.Comment: 3 pages, 2 figure
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