1,577 research outputs found
Equilibrium fluctuation theorems compatible with anomalous response
Previously, we have derived a generalization of the canonical fluctuation
relation between heat capacity and energy fluctuations , which is able to describe the existence of macrostates with negative
heat capacities . In this work, we extend our previous results for an
equilibrium situation with several control parameters to account for the
existence of states with anomalous values in other response functions. Our
analysis leads to the derivation of three different equilibrium fluctuation
theorems: the \textit{fundamental and the complementary fluctuation theorems},
which represent the generalization of two fluctuation identities already
obtained in previous works, and the \textit{associated fluctuation theorem}, a
result that has no counterpart in the framework of Boltzmann-Gibbs
distributions. These results are applied to study the anomalous susceptibility
of a ferromagnetic system, in particular, the case of 2D Ising model.Comment: Extended version of the paper published in JSTA
Extending canonical Monte Carlo methods II
Previously, we have presented a methodology to extend canonical Monte Carlo
methods inspired on a suitable extension of the canonical fluctuation relation
compatible with negative heat capacities .
Now, we improve this methodology by introducing a better treatment of finite
size effects affecting the precision of a direct determination of the
microcanonical caloric curve , as well as
a better implementation of MC schemes. We shall show that despite the
modifications considered, the extended canonical MC methods possibility an
impressive overcome of the so-called \textit{super-critical slowing down}
observed close to the region of a temperature driven first-order phase
transition. In this case, the dependence of the decorrelation time with
the system size is reduced from an exponential growth to a weak power-law
behavior , which is shown in the particular case of
the 2D seven-state Potts model where the exponent .Comment: Version submitted to JSTA
Geometrical aspects and connections of the energy-temperature fluctuation relation
Recently, we have derived a generalization of the known canonical fluctuation
relation between heat capacity and
energy fluctuations, which can account for the existence of macrostates with
negative heat capacities . In this work, we presented a panoramic overview
of direct implications and connections of this fluctuation theorem with other
developments of statistical mechanics, such as the extension of canonical Monte
Carlo methods, the geometric formulations of fluctuation theory and the
relevance of a geometric extension of the Gibbs canonical ensemble that has
been recently proposed in the literature.Comment: Version accepted for publication in J. Phys. A: Math and The
Classification of life by the mechanism of genome size evolution
The classification of life should be based upon the fundamental mechanism in
the evolution of life. We found that the global relationships among species
should be circular phylogeny, which is quite different from the common sense
based upon phylogenetic trees. The genealogical circles can be observed clearly
according to the analysis of protein length distributions of contemporary
species. Thus, we suggest that domains can be defined by distinguished
phylogenetic circles, which are global and stable characteristics of living
systems. The mechanism in genome size evolution has been clarified; hence main
component questions on C-value enigma can be explained. According to the
correlations and quasi-periodicity of protein length distributions, we can also
classify life into three domains.Comment: 53 pages, 9 figures, 2 table
Thermodynamic fluctuation relation for temperature and energy
The present work extends the well-known thermodynamic relation for the canonical ensemble. We start from the general
situation of the thermodynamic equilibrium between a large but finite system of
interest and a generalized thermostat, which we define in the course of the
paper. The resulting identity can account for thermodynamic states
with a negative heat capacity ; at the same time, it represents a
thermodynamic fluctuation relation that imposes some restrictions on the
determination of the microcanonical caloric curve . Finally, we comment briefly on the implications of the present
result for the development of new Monte Carlo methods and an apparent analogy
with quantum mechanics.Comment: Version accepted for publication in J. Phys. A: Math and The
Fluctuation geometry: A counterpart approach of inference geometry
Starting from an axiomatic perspective, \emph{fluctuation geometry} is
developed as a counterpart approach of inference geometry. This approach is
inspired on the existence of a notable analogy between the general theorems of
\emph{inference theory} and the the \emph{general fluctuation theorems}
associated with a parametric family of distribution functions
, which describes the behavior of a set of
\emph{continuous stochastic variables} driven by a set of control parameters
. In this approach, statistical properties are rephrased as purely
geometric notions derived from the \emph{Riemannian structure} on the manifold
of stochastic variables . Consequently, this theory
arises as an alternative framework for applying the powerful methods of
differential geometry for the statistical analysis. Fluctuation geometry has
direct implications on statistics and physics. This geometric approach inspires
a Riemannian reformulation of Einstein fluctuation theory as well as a
geometric redefinition of the information entropy for a continuous
distribution.Comment: Version submitted to J. Phys. A. 26 pages + 2 eps figure
Proper motions of the HH1 jet
We describe a new method for determining proper motions of extended objects,
and a pipeline developed for the application of this method. We then apply this
method to an analysis of four epochs of [S~II] HST images of the HH~1 jet
(covering a period of ~yr).
We determine the proper motions of the knots along the jet, and make a
reconstruction of the past ejection velocity time-variability (assuming
ballistic knot motions). This reconstruction shows an "acceleration" of the
ejection velocities of the jet knots, with higher velocities at more recent
times. This acceleration will result in an eventual merging of the knots in
~yr and at a distance of from the outflow source, close to
the present-day position of HH~1.Comment: 12 pages, 8 figure
Liraglutide and weight loss among patients with advanced heart failure and a reduced ejection fraction: Insights from the FIGHT trial
A computationally efficient reduced order model to generate multi-parameter fluid-thermal databases
A reduced order model (ROM) is proposed to generate multi-parameter databases of some fluid-thermal problems, using a combination of proper orthogonal decomposition, a gradient-like method, and a continuation method. The resulting ROM greatly reduces the CPU time required by slower methods based on genetic algorithm formulations. As a byproduct, the number of required snapshots is also reduced, which yields an additional improvement of the computational efficiency. The work presented in this article aims to facilitate the use of ROMs in industrial environments, in which time is a very important asset. The methodology is illustrated with the non-isothermal flow past a backward-facing step in the laminar regime, which is a representative problem, related to the engineering design of micro-heat sinks
- …