Dynamical mechanisms leading to equilibration in two-component gases

Demonstrating how microscopic dynamics cause large systems to approach thermal equilibrium remains an elusive, longstanding, and actively-pursued goal of statistical mechanics. We identify here a dynamical mechanism for thermalization in a general class of two-component dynamical Lorentz gases, and prove that each component, even when maintained in a non-equilibrium state itself, can drive the other to a thermal state with a well-defined effective temperature.Comment: 5 pages, 5 figure

Eine neue Brombeerart aus Spanien

Rubus lucensis H. E. WEBER & MONASTERIO-HUELIN (sect. Rubus ser. Pallidi W. C. R. WATSON) wird als neue Art beschrieben und abgebildet. Sie wurde bislang in zwei weit voneinander entfernten Gebieten Nordspaniens (Provinzen Lugo und Logroño) nachgewiesen.Rubus lucensis H. E. WEBER & MONASTERIO-HUELIN (sect. Rubus ser. Pallidi W. C. R. WATSON) is described as a new species and illustrated. Up till now it has been tound at two localities far away trom each other in northern Spain (provinces Lugo and Logroño).Se describe e iconogratia Rubus lucensis H. E. WEBER & MONASTERIO-HUELIn spec. nov. (sec. Rubus ser, PALLIDI W. C. R. WATSON), specie que se distribuye por dos localidades, muy distantes entre si, del norte des Espana (provicias de Lugo y Logroño)

Memory Effects in Nonequilibrium Transport for Deterministic Hamiltonian Systems

We consider nonequilibrium transport in a simple chain of identical mechanical cells in which particles move around. In each cell, there is a rotating disc, with which these particles interact, and this is the only interaction in the model. It was shown in \cite{eckmann-young} that when the cells are weakly coupled, to a good approximation, the jump rates of particles and the energy-exchange rates from cell to cell follow linear profiles. Here, we refine that study by analyzing higher-order effects which are induced by the presence of external gradients for situations in which memory effects, typical of Hamiltonian dynamics, cannot be neglected. For the steady state we propose a set of balance equations for the particle number and energy in terms of the reflection probabilities of the cell and solve it phenomenologically. Using this approximate theory we explain how these asymmetries affect various aspects of heat and particle transport in systems of the general type described above and obtain in the infinite volume limit the deviation from the theory in \cite{eckmann-young} to first-order. We verify our assumptions with extensive numerical simulations.Comment: Several change

Editorial: Understanding extreme sports: a psychological perspective

No abstract availabl

What is so special about wingsuit BASE jumpers? A comparative study of their psychological characteristics

For the general public, BASE jumping is considered the ultimate extreme activity. Among BASE jumpers, those using wingsuits are generally perceived as the most experienced but also as the most risk-taking. Starting from this observation, we wanted to know whether wingsuit users differed in their psychological characteristics from other BASE jumpers. More specifically, we hypothesized that wingsuit users would be characterized by higher levels of mental toughness and by lower levels of harm avoidance. We also expected them to use more mental training techniques than the other jumpers. To this end, we conducted a vast survey on a sample of 183 BASE jumpers. Contrary to our hypotheses, the results did not reveal any significant difference in psychological characteristics between wingsuit users and other BASE jumpers. This absence of significant differences is discussed and recommendations for the use of mixed or multi-methods in the study of extreme sports are proposed

Influence of the Stimulation Current on the Differences between Cell and Tissue Electrophysiological Simulations

This study compares stimulation waveforms for single-cell simulations. The alternatives include monophasic and biphasic current pulses, and a new waveform that resembles the transmembrane current responsible for conduction in tissue. Results indicate that the new stimulation produces the lowest mismatch between action potential markers simulated in cell and in tissue. In comparison with the monophasic stimulation, the new stimulation reduced cell-fiber differences by 99% for triangulation, by 95% for maximum transmembrane voltage, and by 76% for the maximum voltage slope. In conclusion, the new stimulation waveform could help to improve the trustworthiness of single-cell simulations in studies involving tissue-derived markers

Third quantization: a general method to solve master equations for quadratic open Fermi systems

The Lindblad master equation for an arbitrary quadratic system of n fermions is solved explicitly in terms of diagonalization of a 4n x 4n matrix, provided that all Lindblad bath operators are linear in the fermionic variables. The method is applied to the explicit construction of non-equilibrium steady states and the calculation of asymptotic relaxation rates in the far from equilibrium problem of heat and spin transport in a nearest neighbor Heisenberg XY spin 1/2 chain in a transverse magnetic field.Comment: 24 pages, with 8 eps figures - few minor corrections to the published version, e.g. anti-symmetrizing the matrix given by eq. (27

Nonequilibrium dynamics of a stochastic model of anomalous heat transport

We study the dynamics of covariances in a chain of harmonic oscillators with conservative noise in contact with two stochastic Langevin heat baths. The noise amounts to random collisions between nearest-neighbour oscillators that exchange their momenta. In a recent paper, [S Lepri et al. J. Phys. A: Math. Theor. 42 (2009) 025001], we have studied the stationary state of this system with fixed boundary conditions, finding analytical exact expressions for the temperature profile and the heat current in the thermodynamic (continuum) limit. In this paper we extend the analysis to the evolution of the covariance matrix and to generic boundary conditions. Our main purpose is to construct a hydrodynamic description of the relaxation to the stationary state, starting from the exact equations governing the evolution of the correlation matrix. We identify and adiabatically eliminate the fast variables, arriving at a continuity equation for the temperature profile T(y,t), complemented by an ordinary equation that accounts for the evolution in the bulk. Altogether, we find that the evolution of T(y,t) is the result of fractional diffusion.Comment: Submitted to Journal of Physics A, Mathematical and Theoretica

Investigation of the strength of beef bone

Thesis (B.S.)--Massachusetts Institute of Technology, Dept. of Business and Engineering Administration, 1920.by J. E. Cassidy and E. R. Monasterio.B.S

Boundary layers in stochastic thermodynamics

We study the problem of optimizing released heat or dissipated work in stochastic thermodynamics. In the overdamped limit these functionals have singular solutions, previously interpreted as protocol jumps. We show that a regularization, penalizing a properly defined acceleration, changes the jumps into boundary layers of finite width. We show that in the limit of vanishing boundary layer width no heat is dissipated in the boundary layer, while work can be done. We further give a new interpretation of the fact that the optimal protocols in the overdamped limit are given by optimal deterministic transport (Burgers equation).Comment: 5 pages, 2 figure