12,600 research outputs found
Out of Equilibrium Solutions in the -Hamiltonian Mean Field model
Out of equilibrium magnetised solutions of the -Hamiltonian Mean Field
(-HMF) model are build using an ensemble of integrable uncoupled pendula.
Using these solutions we display an out-of equilibrium phase transition using a
specific reduced set of the magnetised solutions
Non-equilibrium dynamics of gene expression and the Jarzynski equality
In order to express specific genes at the right time, the transcription of
genes is regulated by the presence and absence of transcription factor
molecules. With transcription factor concentrations undergoing constant
changes, gene transcription takes place out of equilibrium. In this paper we
discuss a simple mapping between dynamic models of gene expression and
stochastic systems driven out of equilibrium. Using this mapping, results of
nonequilibrium statistical mechanics such as the Jarzynski equality and the
fluctuation theorem are demonstrated for gene expression dynamics. Applications
of this approach include the determination of regulatory interactions between
genes from experimental gene expression data
Gravitational diffraction radiation
We show that if the visible universe is a membrane embedded in a
higher-dimensional space, particles in uniform motion radiate gravitational
waves because of spacetime lumpiness. This phenomenon is analogous to the
electromagnetic diffraction radiation of a charge moving near to a metallic
grating. In the gravitational case, the role of the metallic grating is played
by the inhomogeneities of the extra-dimensional space, such as a hidden brane.
We derive a general formula for gravitational diffraction radiation and apply
it to a higher-dimensional scenario with flat compact extra dimensions.
Gravitational diffraction radiation may carry away a significant portion of the
particle's initial energy. This allows to set stringent limits on the scale of
brane perturbations. Physical effects of gravitational diffraction radiation
are briefly discussed.Comment: 5 pages, 2 figures, RevTeX4. v2: References added. Version to appear
in Phys. Rev.
Scheduling non-urgent patient transportation while maximizing emergency coverage
Many ambulance providers operate both advanced life support (ALS) and basic life support (BLS) ambulances. Typically, only an ALS ambulance can respond to an emergency call, whereas non-urgent patient transportation requests can be served by either an ALS or a BLS ambulance. The total capacity of BLS ambulances is usually not enough to fulfill all non-urgent transportation requests. The remaining transportation requests then have to be performed by ALS ambulances, which reduces the coverage for emergency calls. We present a model that determines the routes for BLS ambulances while maximizing the remaining coverage by ALS ambulances. Different from the classical dial-a-ride problem, only one patient can be transported at a time, and not all requests are known in advance. Throughout the day, new requests arrive, and we present an online model to deal with these requests
Trajectory Deflection of Spinning Magnetic Microparticles, the Magnus Effect at the Microscale
The deflection due to the Magnus force of magnetic particles with a diameter
of 80 micrometer dropping through fluids and rotating in a magnetic field was
measured. With Reynolds number for this experiment around 1, we found
trajectory deflections of the order of 1 degree, in agreement within
measurement error with theory. This method holds promise for the sorting and
analysis of the distribution in magnetic moment and particle diameter of
suspensions of microparticles, such as applied in catalysis, or objects loaded
with magnetic particles.Comment: 12 pages, 3 figures. Appendix with 6 figure
Pump-probe scheme for electron-photon dynamics in hybrid conductor-cavity systems
Recent experiments on nanoscale conductors coupled to microwave cavities put
in prospect transport investigations of electron-photon interplay in the deep
quantum regime. Here we propose a pump-probe scheme to investigate the
transient dynamics of individual electron-photon excitations in a double
quantum dot-cavity system. Excitations pumped into the system decay via charge
tunneling at the double dot, probed in real time. We investigate theoretically
the short-time charge transfer statistics at the dot, for periodic pumping, and
show that this gives access to vacuum Rabi oscillations as well as excitation
dynamics in the presence of double dot dephasing and relaxation.Comment: 5 Pages, 5 figure
Compact Waves in Microscopic Nonlinear Diffusion
We analyze the spread of a localized peak of energy into vacuum for nonlinear
diffusive processes. In contrast with standard diffusion, the nonlinearity
results in a compact wave with a sharp front separating the perturbed region
from vacuum. In spatial dimensions, the front advances as
according to hydrodynamics, with the nonlinearity exponent. We show that
fluctuations in the front position grow as , where
is a new exponent that we measure and is a random
variable whose distribution we characterize. Fluctuating corrections to
hydrodynamic profiles give rise to an excess penetration into vacuum, revealing
scaling behaviors and robust features. We also examine the discharge of a
nonlinear rarefaction wave into vacuum. Our results suggest the existence of
universal scaling behaviors at the fluctuating level in nonlinear diffusion.Comment: 5 pages, 4 figure
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