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

Mixed-Status Latinx Families: Love and Chosen Family as a Means of Resistance to the American Dream

This article is featured in the journal Tapestries: Interwoven voices of local and global identities, volume 4

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

The impact of Colombia's pension and health insurance systems on informality

Social protection systems in developing countries are typically composed of a bundle of benefits, the major ones being health insurance and pensions. Benefit bundling may increase informality and decrease welfare. Indeed, if some of the benefits are valued at substantially less than their cost, workers may choose to forego all benefits, even though some other benefits are valued at or above their cost. We examine the impact of benefit bundling using a series of Colombian reforms. The key reform is the unification of the payment systems for health and pension, which made it more difficult to contribute differently to the one plan versus the other. Using the progressive roll-out of the unified payment system by firm size, we show that benefit bundling increases both full formality and full informality by about 1 percentage point. The increase in full formality is concentrated among salaried workers in small to medium firms, while the increase in full informality is concentrated among independent workers

Heart Rate Variability and Multi-Site Pulse Rate Variability for the Assessment of Autonomic Responses to Whole-Body Cold Exposure

Heart rate variability (HRV) is a noninvasive marker of cardiac autonomic activity and has been used in different circumstances to assess the autonomic responses of the body. Pulse rate variability (PRV), a similar variable obtained from pulse waves, has been used in recent years as a valid surrogate of HRV. However, the effect that localized changes in autonomic activity have in the relationship between HRV and PRV has not been entirely understood. In this study, a whole-body cold exposure protocol was performed to generate localized changes in autonomic activity, and HRV and PRV from different body sites were obtained. PRV measured from the earlobe and the finger was shown to differ from HRV, and the correlation between these variables was affected by the cold. Also, it was found that PRV from the finger was more affected by cold exposure than PRV from the earlobe. In conclusion, PRV is affected differently to HRV when localized changes in autonomic activity occur. Hence, PRV should not be considered as a valid surrogate of HRV under certain circumstances.Clinical Relevance - This indicates that pulse rate variability is affected differently to heart rate variability when autonomic activity is modified and suggests that pulse rate variability is not always a valid surrogate of heart rate variability

Stabilization of explicit methods for convection diffusion equations by discrete mollification

AbstractThe main goal of this paper is to show that discrete mollification is a simple and effective way to speed up explicit time-stepping schemes for partial differential equations. The second objective is to enhance the mollification method with a variety of alternatives for the treatment of boundary conditions. The numerical experiments indicate that stabilization by mollification is a technique that works well for a variety of explicit schemes applied to linear and nonlinear differential equations