Generalized Kinetic Theory of Electrons and Phonons

A Generalized Kinetic Theory was proposed in order to have the possibility to treat particles which obey a very general statistics. By adopting the same approach, we generalize here the Kinetic Theory of electrons and phonons. Equilibrium solutions and their stability are investigated.Comment: Proceedings of the International School and Workshop on Nonextensive Thermodynamics and Physical Applications, NEXT 2001, 23-30 May 2001, Cagliari (Italy) (To appear in Physica A

Generalized Kinetic Equations for a System of Interacting Atoms and Photons: Theory and Simulations

In the present paper we introduce generalized kinetic equations describing the dynamics of a system of interacting gas and photons obeying to a very general statistics. In the space homogeneous case we study the equilibrium state of the system and investigate its stability by means of Lyapounov's theory. Two physically relevant situations are discussed in details: photons in a background gas and atoms in a background radiation. After having dropped the statistics generalization for atoms but keeping the statistics generalization for photons, in the zero order Chapmann-Enskog approximation, we present two numerical simulations where the system, initially at equilibrium, is perturbed by an external isotropic Dirac's delta and by a constant source of photons.Comment: 24 pages, 4 figures, IOP macro style, accepted on J. Phys. A: Math. Ge

Travelling waves in a mixture of gases with bimolecular reversible reactions

Starting from the kinetic approach for a mixture of reacting gases whose particles interact through elastic scattering and a bimolecular reversible chemical reaction, the equations that govern the dynamics of the system are obtained by means of the relevant Boltzmann-like equation. Conservation laws are considered. Fluid dynamic approximations are used at the Euler level to obtain a close set of PDEs for six unknown macroscopic fields. The dispersion relation of the mixture of reacting gases is explicitly derived in the homogeneous equilibrium state. A set of ODE that governs the propagation of a plane travelling wave is obtained using the Galilei invariance. After numerical integration some solutions, including the well-known Maxwellian and the hard spheres cases, are found for various meaningful interaction laws. The main macroscopic observables for the gas mixture such as the drift velocity, temperature, total density, pressure and its chemical composition are shown.Comment: 13 pages, 2 figures, accepted on Physica

Generalized Kinetic Theory of Electrons and Phonons: Models, Equilibrium, Stability

In the present paper our aim is to introduce some models for the generalization of the kinetic theory of electrons and phonons (KTEP), as well as to study equilibrium solutions and their stability for the generalized KTEP (GKTEP) equations. We consider a couple of models, relevant to non standard quantum statistics, which give rise to inverse power law decays of the distribution function with respect to energy. In the case of electrons in a phonon background, equilibrium and stability are investigated by means of Lyapounov theory. Connections with thermodynamics are pointed out.Comment: 10 pages, 2 figures, (RevTeX4), to appear in Physica B (2003

COVID-19: Protocolo de guerra frente a la pandemia: COVID-19: War protocol to fight the pandemic

During the medical training years, in one way or another, we have obtained knowledge and have prepared in the best possible way for emergencies and/or natural disasters. In the last 25 years, action protocols have been executed and implemented in a successful manner before endemics, epidemics and pandemics, such as Influenza, Ebola and SARS.What we have been observing in the last 3 months makes us reflect on the reactions before this global emergency and the ethical problems that have emerged due to COVID-19. We are moved and it sparks diverse reactions that to look beyond the initial emotions and generosity.Durante los años de formación médica, de alguna u otra manera, hemos tenido conocimiento y noshemos preparado de la mejor forma posible para las emergencias y/o desastres naturales. Durante losúltimos 25 años se han ejecutado protocolos de acción implementados de manera eficaz frente a hechosendemias, epidemias y pandemias como la Influenza, el Ébola y el Sars. Lo que estamos observando en estos 3 últimos meses nos hace reflexionar sobre las reacciones a estaemergencia mundial y a los problemas éticos que han surgido a raíz del COVID-19. Nos conmueven ydespiertan reacciones diversas que exigen una mirada más allá de lo emocional y de la generosidadinicial

Generalized Pearson distributions for charged particles interacting with an electric and/or a magnetic field

The linear Boltzmann equation for elastic and/or inelastic scattering is applied to derive the distribution function of a spatially homogeneous system of charged particles spreading in a host medium of two-level atoms and subjected to external electric and/or magnetic fields. We construct a Fokker-Planck approximation to the kinetic equations and derive the most general class of distributions for the given problem by discussing in detail some physically meaningful cases. The equivalence with the transport theory of electrons in a phonon background is also discussed.Comment: 24 pages, version accepted on Physica

COVID-19: Revisión de la literatura y su impacto en la realidad sanitaria peruana: COVID-19: Literature review and its impact on the Peruvian health reality

Introduction: The disease called COVID-19 is a pandemic caused by the SARS-CoV-2 virus (severe acute respiratory syndrome 2). In Peru, patient zero or first case with COVID-19 was detected on March 6 and since then the virus has continued to spread. The national government fights against this disease on several fronts, but the health situation differs greatly from developed countries. Objective: To review the current state of the disease and analyze its possible impact on the Peruvian health system. Methods: A bibliographic search of various studies was carried out since the appearance of the disease (December 2019) in the different databases (PUBMED, MEDLINE, PLOs, SciELO) and in Google Scholar. Results: It was found that the virus is transmitted mainly by the respiratory route; the average incubation period is 14 days; most patients have mild disease or are asymptomatic but 5% of these will require hospitalization, some will even require intensive therapy with mechanical ventilation; the current treatment is basically symptomatic, but antibiotics, antivirals and antiparasitics have also been used. Conclusions: The quarantine with strict measures of isolation and social distancing is accurate given the Peruvian health reality and the imminent contagion of the population.Introducción: La enfermedad denominada COVID-19 es una pandemia causada por el virus SARS-CoV-2 (síndrome agudo respiratorio severo 2). En el Perú, el paciente cero o primer caso con COVID-19 fue detectado el último 6 de marzo y desde entonces el virus continúa su propagación. El gobierno nacional lucha contra esta enfermedad desde varios frentes, pero la situación sanitaria difiere mucho con la de países desarrollados. Objetivo: Revisar el estado actual de la enfermedad y analizar su posible impacto en el sistema de salud peruano. Métodos: Se realizó una búsqueda bibliográfica de diversos estudios desde la aparición de la enfermedad (diciembre 2019) en las diferentes bases de datos (PUBMED, MEDLINE, PLOs, SciELO) y también en Google Académico. Resultados: Se encontró que el virus se trasmite principalmente por vía respiratoria; el periodo de incubación promedio es 14 días; la mayoría de los pacientes tienen una enfermedad leve o son asintomáticos pero un 5% de estos requerirá hospitalización, algunos incluso requerirán terapia intensiva con ventilación mecánica; el tratamiento actual es básicamente sintomático, pero también antibióticos, antivirales y antiparasitarios. Conclusiones: La cuarentena con medidas estrictas de aislamiento y distanciamiento social es precisa, dada la realidad sanitaria peruana y el inminente contagio de la población

Lateral Supraorbital Approach : Simple, Clean, and Preserving Normal Anatomy

Objective The anterior skull base region can be reached through different surgical approaches. The most frequently used are the pterional, bifrontal, and orbitozygomatic approaches. No previous reports describe the microsurgical technique when treating olfactory groove meningiomas (OGMs), anterior clinoidal meningiomas (ACMs), and tuberculum sellae meningiomas (TSMs)through the small lateral supraorbital (LSO) approach. The purpose here was to assess the reliability and safety of the LSO for the treatment of vascular and neoplastic lesions of the anterior skull base. The neuroanesthesia method when using this small approach is also presented. When needed, anterior clinoidectomy, intradurally or extradurally, is also possible through the LSO approach. Patients and Methods Between September 1997 and August 2010, we analyzed the clinical data, radiological findings, surgical treatment, anesthesiological procedure, histology, outcome, and long-term follow-up of 66 OGMs, 73 ACMs, 52 TSMs consecutive patients treated by the senior author (J.H.) through the LSO approach. Anterior clinoidectomy technique through the LSO is presented after reviewing 82 patients who underwent surgery for vascular and neoplastic lesions between June 2007 and January 2011. Altogether 273 patients of a total of 3000 LSO approaches were analyzed, and 15 videos were selected to show the approach and the microsurgical techniques used. Results Olfactory groove meningiomas: There was no surgical mortality. Six patients (9%) had CSF leakage, four (6%) had wound infections and cotton granulomas, and one (2%) had postoperative hematoma. The median Karnofsky score at discharge was 80 (range, 40-100). Six patients had residual tumors: three were re-operated on after an average of 21 (range, 1-41) months, one was treated with radiosurgery, and two were followed up. During the median follow-up of 45 (range, 2-128) months there were four recurrences (6%) diagnosed on average 32 (range, 17-59) months after surgery. Anterior clinoidal meningiomas: At three months after discharge, 60 patients (82%) had a good recovery, nine (12%) were moderately disabled, one (1%) presented with severe disability, and three (4%) died due to surgery-related complications. Sixteen patients (22%) had residual tumors, six of which required re-operation. Of 39 patients, pre-existing visual deficit improved in 11 (28%), worsened in four (5%), and three (4%) had de novo visual deficit. During the median follow-up of 36 (range, 3-146) months tumor recurred in three patients: two were followed up and one was reoperated. Tuberculum sellae meningiomas: At three months postdischarge, 47 patients (90%) had a good recovery, four (8%) were moderately disabled, and one (2%) died 40 days after surgery of unexplained cardiac arrest. Of 42 patients, pre-existing visual deficit improved in 22 (42%), remained the same in 13 (25%), and worsened in seven (13%), and de novo visual deficit occurred in one patient (2%). Seven patients (13%) had minimal residual tumors, two of which required re-operation. During the median follow-up of 59 (range, 1-133) months tumor recurred in one of the patients who had received a second operation. Anesthesia: Surgical conditions with slack brain were good in 154 meningioma patients. Slack brain was achieved by a head position elevated 20 cm above cardiac level in all patients; administering mannitol preoperatively in medium or large meningiomas (60 cases); propofol infusion (46 cases) or volatile anesthetics (107 cases) also in patients with large tumor (37 cases); and controlling intraoperative hemodynamics. The mean systolic blood pressure was 95-110 mmHg during surgery. The median intraoperative blood loss was 200 (range, 0-2000) ml and 9% of patients had red blood cell transfusion. One-hundred and fifty-seven patients (84%) were extubated on the day of the surgery. The median (25th/75th percentiles) time to extubation after surgery was 18 (8/105) min. Anterior clinoidectomy: Eighty-two patients underwent anterior clinoidectomy: 45 patients (55%) were treated for aneurysms, 35 patients (43%) were treated for intraorbital, parasellar, and suprasellar tumors, and two patients (2%) presented with carotid-cavernous fistula. Intradural anterior clinoidectomy was performed in 67 cases (82%); in 15 cases (18%), an extradural approach was used. We performed a tailored anterior clinoidectomy: in five patients (6%), only the medial tip of the anterior clinoid process (ACP) was removed, in eight (10%) the head of the ACP, in 18 (22%) the body of the ACP, and in 51 (62%) the entire ACP. Four patients (5%) had new postoperative visual deficits and 12 (15%) improved their preoperative visual deficits after intradural anterior clinoidectomy. Extradural anterior clinoidectomy and use of ultrasonic bone device (Sonopet) may increase the risk of postoperative visual deficits. There was no mortality in the series. Conclusions The LSO approach can be used safely for OGMs, ACMs, and TSMs of all sizes, with a low mortality and a relatively low morbidity. Anterior clinoidectomy can be performed through the LSO approach. However, it is required only in selected cases and we prefer the intradural route. A slack brain is mandatory when performing the small LSO approach and can be achieved by patient positioning, propofol or inhaled anesthetics, preoperative mannitol, and optimizing cerebral perfusion pressure. With advancements in the neurosurgical field, the skull opening should be simple and as minimally invasive as possible. Surgical results with the simple, clean, and fast LSO approach are comparable with those achieved with more extensive, complex, and time-consuming approaches. We highly recommend the use of LSO for removal of vascular and neoplastic lesions of the anterior skull base.Ei saatavill

Intensive variables in the framework of the non-extensive thermostatistics

By assuming an appropriate energy composition law between two systems governed by the same non-extensive entropy, we revisit the definitions of temperature and pressure, arising from the zeroth principle of thermodynamics, in a manner consistent with the thermostatistics structure of the theory. We show that the definitions of these quantities are sensitive to the composition law of entropy and internal energy governing the system. In this way, we can clarify some questions raised about the possible introduction of intensive variables in the context of non-extensive statistical mechanics.Comment: 14 pages, elsart style, version accepted on Physics Letters