Reinaldo García-García

Reinaldo García-García
  • PhD in Physics
  • Profesor Contratado Doctor (Associate Professor) at Universidad de Navarra

Nonequilibrium Statistical Mechanics, Stochastic Thermodynamics, Disordered Elastic Systems, Soft and Active Matter.

About

40
Publications
8,976
Reads
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423
Citations
Introduction
Reinaldo García García is a theoretical physicist currently studying the statistical properties of complex nonequilibrium systems. He is particularly interested in the physics of disordered materials, and in the mathematical modelling of active and living systems. He is also currently working on problems related to heterogeneous condensation patterns and Breath Figures.
Current institution
Universidad de Navarra
Current position
  • Profesor Contratado Doctor (Associate Professor)
Additional affiliations
February 2016 - April 2017
ESPCI Paris
Position
  • PostDoc Position
May 2014 - January 2015
École Polytechnique, and, ESPCI-ParisTech.
Position
  • PostDoc Position
April 2014 - present
ESPCI ParisTech- CNRS
Position
  • PostDoc Position
Education
September 2000 - July 2005
University of Havana
Field of study
  • Physics

Publications

Publications (40)
Article
Full-text available
A brief review is made of the birth and evolution of the “nonequilibrium potential” (NEP) concept. As if providing a landscape for qualitative reasoning were not helpful enough, the NEP adds a quantitative dimension to the qualitative theory of differential equations and provides a global Lyapunov function for the deterministic dynamics. Here we il...
Preprint
Full-text available
The coarse-graining of amorphous plasticity from the atomistic to the mesoscopic scale is studied in the framework of a simple scalar elasto-plastic model. Building on recent results obtained on the atomistic scale, we discuss the interest in a disordered landscape-informed threshold disorder to reproduce the physics of amorphous plasticity. We sho...
Article
Cross‐species communication, where signals are sent by one species and perceived by others, is one of the most intriguing types of communication that functionally links different species to form complex ecological networks. Global change and human activity can affect communication by increasing fluctuations in species composition and phenology, alt...
Article
Full-text available
We study the Stochastic Thermodynamics of cell growth and division using a theoretical framework based on branching processes with resetting. Cell division may be split into two sub-processes: branching, by which a given cell gives birth to an identical copy of itself, and resetting, by which some properties of the daughter cells (such as their siz...
Article
Full-text available
A brief review is made of the birth and evolution of the ‘‘nonequilibrium potential’’ (NEP) concept. As if providing a landscape for qualitative reasoning were not helpful enough, the NEP adds a quantitative dimension to the qualitative theory of differential equations and provides a global Lyapunov function for the deterministic dynamics. Here we...
Preprint
Full-text available
We study the Stochastic Thermodynamics of cell growth and division using a theoretical framework based on branching processes with resetting. Cell division may be split into two sub-processes: branching, by which a given cell gives birth to an identical copy of itself, and resetting, by which some properties of the daughter cells (such as their siz...
Preprint
Full-text available
Cross-species communication, where signals are sent by one species and perceived by others, is one of the most intriguing types of communication that functionally links different species to form complex ecological networks. Yet, global changes and human activities can affect communication by increasing the fluctuations of species composition and ph...
Article
Full-text available
We develop a maximum likelihood method to infer relevant physical properties of elongated active particles. Using individual trajectories of advected swimmers as input, we are able to accurately determine their rotational diffusion coefficients and an effective measure of their aspect ratio, also providing reliable estimators for the uncertainties...
Preprint
Full-text available
We develop a maximum likelihood method to infer relevant physical properties of elongated active particles. Using individual trajectories of advected swimmers as input, we are able to accurately determine their rotational diffusion coefficients and an effective measure of their aspect ratio, also providing reliable estimators for the uncertainties...
Article
To account for the possibility of an externally driven taxis in active systems, we develop a model of a guided active drift which relies on the presence of an external guiding field and a vectorial coupling between the mechanical degrees of freedom and a chemical reaction. To characterize the ability of guided active particles to carry cargo, we ge...
Preprint
Full-text available
To account for the possibility of an externally driven taxis in active systems, we develop a model of a guided active drift (GAD) which relies on the presence of an external guiding field and a vectorial coupling between the mechanical degrees of freedom and a chemical reaction. To characterize the ability of guided active particles to carry cargo...
Article
Full-text available
Using a population dynamics inspired by an ensemble of growing cells, a set of fluctuation theorems linking observables measured at the lineage and population levels is derived. One of these relations implies specific inequalities comparing the population doubling time with the mean generation time at the lineage or population levels. While these i...
Poster
Full-text available
We study the statistics of the energy dissipated in individual avalanches at the depinning transition. In the regime dominated by the depinning phenomenology, a relation between the size of an avalanche and its energy can be derived using ”naive” scaling arguments and verified in mean-field systems. This relation allows to design a method to determ...
Preprint
Full-text available
Using a population dynamics inspired by an ensemble of growing cells, a set of fluctuation theorems linking observables measured at the lineage and population levels are derived. One of these relations implies inequalities comparing the population doubling time with the mean generation time at the lineage or population levels. We argue that testing...
Preprint
Using a population dynamics inspired by an ensemble of growing cells, a set of fluctuation theorems linking observables measured at the lineage and population levels are derived. One of these relations implies specific inequalities comparing the population doubling time with the mean generation time at the lineage or population levels. While these...
Poster
Full-text available
We focus on the mean velocity induced by a constant force applied on one-dimensional interfaces. In presence of disorder the velocity presents a stretched exponential dependence in the force (the so-called ‘creep law’), which is out of reach of linear response. In dimension one, there is no exact analytical derivation of such a law. We propose an e...
Data
Supplemental Material for "Heat leakage in equilibrium processes". This is a very short text dealing with the proof of an important identity used in the main text, and the calculation of an integral leading to the second main result of the manuscript.
Preprint
Full-text available
The difference between the zero-mass limit of the heat exchanged with a thermal reservoir, and its value as determined from overdamped dynamics, is termed `heat leakage' or `hidden heat' in the Smoluchowski limit. If present, heat leakages are the sign of the unsuitability of the overdamped approximation for addressing thermodynamics. It is accepte...
Research
Full-text available
In these notes I provide a simple derivation of a formal decomposition of the free energy of a directed polymer with fixed end points in presence of a tilting force. The decomposition is explicit in terms of a translationally invariant part, and contribution arising from the external forcing. With that purpose, a modified version of the statistical...
Article
Full-text available
We consider the amount of energy dissipated during individual avalanches at the depinning transition of disordered and athermal elastic systems. Analytical progress is possible in the case of the Alessandro-Beatrice-Bertotti-Montorsi (ABBM) model for Barkhausen noise, due to an exact mapping between the energy released in an avalanche and the area...
Article
Full-text available
We develop and extend a method presented in [S. Patinet, D. Vandembroucq, and M. L. Falk, Phys. Rev. Lett., 117, 045501 (2016)] to compute the local yield stresses at the atomic scale in model two-dimensional Lennard-Jones glasses produced via differing quench protocols. This technique allows us to sample the plastic rearrangements in a non-perturb...
Preprint
We develop and extend a method presented in [S. Patinet, D. Vandembroucq, and M. L. Falk, Phys. Rev. Lett., 117, 045501 (2016)] to compute the local yield stresses at the atomic scale in model two-dimensional Lennard-Jones glasses produced via differing quench protocols. This technique allows us to sample the plastic rearrangements in a non-perturb...
Article
Full-text available
The response of spatially extended systems to a force leading their steady state out of equilibrium is strongly affected by the presence of disorder. We focus on the mean velocity induced by a constant force applied on one-dimensional interfaces. In the absence of disorder, the velocity is linear in the force. In the presence of disorder, it is wid...
Article
Full-text available
Fluctuation theorems have become an important tool in single molecule biophysics to measure free energy differences from non-equilibrium experiments. When significant coarse-graining or noise affect the measurements, the determination of the free energies becomes challenging. In order to address this thermodynamic inference problem, we propose impr...
Article
Full-text available
We introduce the violation fraction $\upsilon$ as the cumulative fraction of time that a mesoscopic system spends consuming entropy at a single trajectory in phase space. We show that the fluctuations of this quantity are described in terms of a symmetry relation reminiscent of fluctuation theorems, which involve a function, $\Phi$, which can be in...
Article
Full-text available
We define the {\it violation fraction} $\nu$ as the cumulative fraction of time that the entropy change is negative during single realizations of processes in phase space. This quantity depends on both the number of degrees of freedom $N$ and the duration of the time interval $\tau$. In the large-$\tau$ and large-$N$ limit we show that, for ergodic...
Article
Full-text available
We define the violation fraction ν as the cumulative fraction of time that the entropy change is negative during single realizations of processes in phase space. This quantity depends both on the number of degrees of freedom N and the duration of the time interval τ . In the large-τ and large-N limit we show that, for ergodic and microreversible sy...
Thesis
Full-text available
We derive a set of exact relations in the context of the stochastic thermodynamics of small out-of-equilibrium systems. We study the symmetries of the total entropy production upon certain involutive transformations (e.g. some transformations such that when applied twice consecutively one is lead to the identity operator). Based on the mentioned sy...
Article
Full-text available
We extend the definition of nonadiabatic entropy production given for Markovian systems by Esposito and Van den Broeck [Phys. Rev. Lett. 104, 090601 (2010)], to arbitrary non-Markov ergodic dynamics. We also introduce a notion of stability characterizing non-Markovianity. For stable non-Markovian systems, the nonadiabatic entropy production satisfi...
Article
Full-text available
We derive various exact results for Markovian systems that spontaneously relax to a non-equilibrium steady state by using joint probability distribution symmetries of different entropy production decompositions. The analytical approach is applied to diverse problems such as the description of the fluctuations induced by experimental errors, for unv...
Article
We study the probability distribution function (PDF) of the position of a Lévy flight of index 0<α<2 in the presence of an absorbing wall at the origin. The solution of the associated fractional Fokker-Planck equation can be constructed using a perturbation scheme around the Brownian solution (corresponding to α=2) as an expansion in ε=2−α. We obta...
Article
We study the statistics of a one-dimensional L\'evy random walks of index 0< \alpha \leq 2 in a semi-bounded domain. We construct a solution of the associated fractional Fokker-Planck equation with non-local boundary conditions using a perturbative expansion in \epsilon = 2 - \alpha
Article
Full-text available
Any decomposition of the total trajectory entropy production for Markovian systems has a joint probability distribution satisfying a generalized detailed fluctuation theorem, when all the contributing terms are odd with respect to time reversal. The expression of the result does not bring into play dual probability distributions, hence easing poten...
Article
Full-text available
Any decomposition of the total trajectory entropy production for Markovian systems has a joint probability distribution satisfying a generalized detailed fluctuation theorem, when all the contributing terms are odd with respect to time reversal. The expression of the result does not bring into play dual probability distributions, hence easing poten...
Preprint
Any decomposition of the total trajectory entropy production for Markovian systems has a joint probability distribution satisfying a generalized detailed fluctuation theorem, when all the contributing terms are odd with respect to time reversal. The expression of the result does not bring into play dual probability distributions, hence easing poten...
Article
Full-text available
We study, using exact numerical simulations, the statistics of the longest excursion l(max)(t) up to time t for the fractional Brownian motion with Hurst exponent 0<H<1. We show that in the large t limit, <l(max)(t)> proportional to variantQ(infinity)t, where Q(infinity) identical with Q(infinity)(H) depends continuously on H. These results are com...
Preprint
We study, using exact numerical simulations, the statistics of the longest excursion l_{\max}(t) up to time t for the fractional Brownian motion with Hurst exponent 0<H<1. We show that in the large t limit, < l_{\max}(t) > \propto Q_\infty t where Q_\infty \equiv Q_\infty(H) depends continuously on H, and in a non trivial way. These results are com...
Article
Full-text available
Josephson effects are macroscopic quantum phenomena that can be understood at the undergraduate level with the help of mechanical analogs. Although Josephson junctions in zero magnetic field can be modeled by pendulum analogs, a simple mechanical model of Josephson junctions in nonzero fields has been elusive. We demonstrate how the magnetic field...

Questions

Questions (4)
Question
Understanding the mechanism behind the glass transition is one of those old problems that has resisted massive efforts and huge grants. Many different models have been invented and discussed and, with time, different schools of thought emerged (among theoreticians) to understand the glass transition. Two notable examples are the school of Kinetically Constrained Models (KCM) and the school of the Random First Order Transition (RFOT).
A huge part of the (theoretical) literature in the previous recent years, focuses either on the debate between these two visions, or on the many problems each of them finds in its own way after each step. This is why it is very difficult to find ideas detached from a given school of thought (at least in recent literature).
As a theoretician, I am naturally interested on the technical developments behind these approaches, nevertheless, I'm also curious about the original problem. So, if one could answer this question without any reference to the pre-existing theories and to their constructions, what are the empirical facts that any successful theory of the glass transition must be able to explain?
Question
Classification of thermodynamic phase transitions relies on the analiticity of the Helmholtz free energy (or the corresponding thermodynamic potential, depending on the ensemble). As it is widely known, first-order phase transitions are characterized by a discontinuity in the first derivative of the thermodynamic potential with respect to the relevant intensive variable, while in continuous phase transitions the thermodynamic potentials are continuous and differentiable, but high-order derivatives may be undefined.
Imagine now that one considers a system udergoing a phase transition for given values of temperature, pressure, etc. Is it possible to infer that such a system will exhibit a thermodynamic phase transition by looking at the microcanonical density of states (DOS), instead of the thermodynamic potentials? Does the DOS carry some signature of the phase transitions? If yes, what traits indicate the order of the transition ?
By studying some classical papers (like those on random energy models and trap models by Derrida), one can infer, for instance, that a DOS with edge states can be linked to a thermodynamic freezing (glass) transition. Are there similar signs in the simpler cases of first and second order phase transitions? I intuitively believe there must be, since, for instance, the canonical partition function is simply the Laplace transform of the microcanonical DOS. But I don't know what those signs may be.

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