A fundamental postulate of statistical mechanics is that all microstates in an isolated system are equally probable. This postulate, which goes back to Boltzmann, has often been criticized for not having a clear physical foundation. In this note, we provide a derivation of the canonical (Boltzmann) distribution that avoids this postulate. In its place, we impose two axioms with physical interpretations. The first axiom (thermal equilibrium) ensures that, as our system of interest comes into contact with different heat baths, the ranking of states of the system by probability is unchanged. Physically, this axiom is a statement that in thermal equilibrium, population inversions do not arise. The second axiom (energy exchange) requires that, for any heat bath and any probability distribution on states, there is a universe consisting of a system and heat bath that can achieve this distribution. Physically, this axiom is a statement that energy flows between system and heat bath are unrestricted. We show that our two axioms identify the Boltzmann distribution.
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http://dx.doi.org/10.1007/s10701-019-00257-z | DOI Listing |
Int J Heat Mass Transf
March 2024
Department of Mechanical and Aerospace Engineering, University of California, Los Angeles, CA 90095, United States of America.
In classical theory, heat conduction in solids is regarded as a diffusion process driven by a temperature gradient, whereas fluid transport is understood as convection process involving the bulk motion of the liquid or gas. In the framework of theory, which is directly built upon quantum mechanics without relying on measured parameters or phenomenological models, we observed and investigated the fluid-like convective transport of energy carriers in solid heat conduction. Thermal transport, carried by phonons, is simulated in graphite by solving the Boltzmann transport equation using a Monte Carlo algorithm.
View Article and Find Full Text PDFStem Cell Res Ther
December 2024
Department of Pharmacology, School of Medicine, Shahid Beheshti University of Medical Sciences, Tehran, Iran.
Objective: Spinal cord injury (SCI) is a severe and permanent nerve damage condition that poses significant burdens on individuals and society. Various therapeutic approaches have been explored to mitigate the consequences of SCI. Tissue engineering and regenerative medicine have emerged as a promising avenue for addressing this issue.
View Article and Find Full Text PDFThe task of RNA design given a target structure aims to find a sequence that can fold into that structure. It is a computationally hard problem where some version(s) have been proven to be NP-hard. As a result, heuristic methods such as local search have been popular for this task, but by only exploring a fixed number of candidates.
View Article and Find Full Text PDFJ R Soc Interface
December 2024
Université Grenoble Alpes, CNRS, LIPhy, Grenoble 38000, France.
Nitric oxide (NO) is an important vasodilator responsible for maintaining vascular tone in the human body. Its production in endothelial cells (ECs) is regulated by the rise of cytoplasmic Ca concentration and shear stress perceived by blood flow. The increase in cytoplasmic Ca concentration is mainly activated by adenosine triphosphate (ATP) released from red blood cells (RBCs) and ECs.
View Article and Find Full Text PDFJ Psychosom Res
December 2024
Division of Hematology and Hemostaseology, Department of Medicine I, Medical University of Vienna, Vienna, Austria; Comprehensive Cancer Center, Medical University of Vienna, Vienna, Austria; Ludwig Boltzmann Institute for Hematology and Oncology, Medical University of Vienna, Vienna, Austria.
Objective: We investigate the prevalence of five affective temperaments (depressive, cyclothymic, hyperthymic, irritable, and anxious) in a large sample of cancer patients and associations of temperament with cancer site as well as the impact of temperament on overall survival of cancer patients.
Methods: Data for this prospective cohort study was collected in the outpatient clinic of a large cancer center. We used the Temperament Evaluation in Memphis, Pisa and San Diego - Münster Version (TEMPS-M) and recorded patient data.
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