2,238 research outputs found
Fluctuation theorem for entropy production during effusion of a relativistic ideal gas
The probability distribution of the entropy production for the effusion of a
relativistic ideal gas is calculated explicitly. This result is then extended
to include particle and anti-particle pair production and annihilation. In both
cases, the fluctuation theorem is verified.Comment: 6 pages, no figure
Thermodynamic time asymmetry in nonequilibrium fluctuations
We here present the complete analysis of experiments on driven Brownian
motion and electric noise in a circuit, showing that thermodynamic entropy
production can be related to the breaking of time-reversal symmetry in the
statistical description of these nonequilibrium systems. The symmetry breaking
can be expressed in terms of dynamical entropies per unit time, one for the
forward process and the other for the time-reversed process. These entropies
per unit time characterize dynamical randomness, i.e., temporal disorder, in
time series of the nonequilibrium fluctuations. Their difference gives the
well-known thermodynamic entropy production, which thus finds its origin in the
time asymmetry of dynamical randomness, alias temporal disorder, in systems
driven out of equilibrium.Comment: to be published in : Journal of Statistical Mechanics: theory and
experimen
A fluctuation theorem for currents and non-linear response coefficients
We use a recently proved fluctuation theorem for the currents to develop the
response theory of nonequilibrium phenomena. In this framework, expressions for
the response coefficients of the currents at arbitrary orders in the
thermodynamic forces or affinities are obtained in terms of the fluctuations of
the cumulative currents and remarkable relations are obtained which are the
consequences of microreversibility beyond Onsager reciprocity relations
Tarlov Cyst: A diagnostic of exclusion.
Tarlov cysts were first described in 1938 as an incidental finding at autopsy. The cysts are usually diagnosed on MRI, which reveals the lesion arising from the sacral nerve root near the dorsal root ganglion. Symptomatic sacral perineural cysts are uncommon and it is recommended to consider Tarlov cyst as a diagnostic of exclusion. We report a case of a patient with voluminous bilateral L5 and S1 Tarlov cyst, and right hip osteonecrosis to increase the awareness in the orthopaedic community. A 57-year-old female, in good health, with chronic low back pain since 20 years, presented suddenly right buttock pain, right inguinal fold pain and low back pain for two months, with inability to walk and to sit down. X-ray of the lumbo-sacral spine revealed asymmetric discopathy L5-S1 and L3-L4. X-ray of the right hip did not reveal anything. We asked for an MRI of the spine and it revealed a voluminous fluid-filled cystic lesion, arising from the first sacral nerve root on both side and measuring 3,3cm in diameter. The MRI also show a part of the hip and incidentally we discovered an osteonecrosis Ficat 3 of the right femoral head. The patient was taken for a total hip arthroplasty, by anterior approach. Patient appreciated relief of pain immediately after the surgery. The current case show that even if we find a voluminous cyst we always have to eliminate other diagnosis (especially the frequent like osteonecrosis of the femoral head) and mostly in the case of unclear neurological perturbation
Fluctuation theorem for counting-statistics in electron transport through quantum junctions
We demonstrate that the probability distribution of the net number of
electrons passing through a quantum system in a junction obeys a steady-state
fluctuation theorem (FT) which can be tested experimentally by the full
counting statistics (FCS) of electrons crossing the lead-system interface. The
FCS is calculated using a many-body quantum master equation (QME) combined with
a Liouville space generating function (GF) formalism. For a model of two
coupled quantum dots, we show that the FT becomes valid for long binning times
and provide an estimate for the finite-time deviations. We also demonstrate
that the Mandel (or Fano) parameter associated with the incoming or outgoing
electron transfers show subpoissonian (antibunching) statistics.Comment: 20 pages, 12 figures, accepted in Phy.Rev.
Gallavotti-Cohen-Type symmetry related to cycle decompositions for Markov chains and biochemical applications
We slightly extend the fluctuation theorem obtained in \cite{LS} for sums of
generators, considering continuous-time Markov chains on a finite state space
whose underlying graph has multiple edges and no loop. This extended frame is
suited when analyzing chemical systems. As simple corollary we derive in a
different method the fluctuation theorem of D. Andrieux and P. Gaspard for the
fluxes along the chords associated to a fundamental set of oriented cycles
\cite{AG2}.
We associate to each random trajectory an oriented cycle on the graph and we
decompose it in terms of a basis of oriented cycles. We prove a fluctuation
theorem for the coefficients in this decomposition. The resulting fluctuation
theorem involves the cycle affinities, which in many real systems correspond to
the macroscopic forces. In addition, the above decomposition is useful when
analyzing the large deviations of additive functionals of the Markov chain. As
example of application, in a very general context we derive a fluctuation
relation for the mechanical and chemical currents of a molecular motor moving
along a periodic filament.Comment: 23 pages, 5 figures. Correction
Stochastic thermodynamics of chemical reaction networks
For chemical reaction networks described by a master equation, we define
energy and entropy on a stochastic trajectory and develop a consistent
nonequilibrium thermodynamic description along a single stochastic trajectory
of reaction events. A first-law like energy balance relates internal energy,
applied (chemical) work and dissipated heat for every single reaction. Entropy
production along a single trajectory involves a sum over changes in the entropy
of the network itself and the entropy of the medium. The latter is given by the
exchanged heat identified through the first law. Total entropy production is
constrained by an integral fluctuation theorem for networks arbitrarily driven
by time-dependent rates and a detailed fluctuation theorem for networks in the
steady state. Further exact relations like a generalized Jarzynski relation and
a generalized Clausius inequality are discussed. We illustrate these results
for a three-species cyclic reaction network which exhibits nonequilibrium
steady states as well as transitions between different steady states.Comment: 14 pages, 2 figures, accepted for publication in J. Chem. Phy
To adapt or not to adapt? Technical debt and learning driven self-adaptation for managing runtime performance
Self-adaptive system (SAS) can adapt itself to optimize various key performance indicators in response to the dynamics and uncertainty in environment. In this paper, we present Debt Learning Driven Adaptation (DLDA), an framework that dynamically determines when and whether to adapt the SAS at runtime. DLDA leverages the temporal adaptation debt, a notion derived from the technical debt metaphor, to quantify the time-varying money that the SAS carries in relation to its performance and Service Level Agreements. We designed a temporal net debt driven labeling to label whether it is economically healthier to adapt the SAS (or not) in a circumstance, based on which an online machine learning classifier learns the correlation, and then predicts whether to adapt under the future circumstances. We conducted comprehensive experiments to evaluate DLDA with two different planners, using 5 online machine learning classifiers, and in comparison to 4 state-of-the-art debt- oblivious triggering approaches. The results reveal the effectiveness and superiority of DLDA according to different metrics
Fluctuation theorem for the effusion of an ideal gas
The probability distribution of the entropy production for the effusion of an
ideal gas between two compartments is calculated explicitly. The fluctuation
theorem is verified. The analytic results are in good agreement with numerical
data from hard disk molecular dynamics simulations.Comment: 11 pages, 10 figures, 2 table
A meaningful expansion around detailed balance
We consider Markovian dynamics modeling open mesoscopic systems which are
driven away from detailed balance by a nonconservative force. A systematic
expansion is obtained of the stationary distribution around an equilibrium
reference, in orders of the nonequilibrium forcing. The first order around
equilibrium has been known since the work of McLennan (1959), and involves the
transient irreversible entropy flux. The expansion generalizes the McLennan
formula to higher orders, complementing the entropy flux with the dynamical
activity. The latter is more kinetic than thermodynamic and is a possible
realization of Landauer's insight (1975) that, for nonequilibrium, the relative
occupation of states also depends on the noise along possible escape routes. In
that way nonlinear response around equilibrium can be meaningfully discussed in
terms of two main quantities only, the entropy flux and the dynamical activity.
The expansion makes mathematical sense as shown in the simplest cases from
exponential ergodicity.Comment: 19 page
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