Anisotropic effects of background fields on Born-Infeld electromagnetic waves

We show exact solutions of Born-Infeld theory for electromagnetic plane waves propagating in the presence of static background fields. The non-linear character of Born-Infeld equations generates an interaction between background and wave that changes the speed of propagation and adds a longitudinal component to the wave. As a consequence, in a magnetic background the ray direction differs from the propagation direction --a behavior resembling the one of a wave in an anisotropic medium--. This feature could open up a way to experimental tests of Born-Infeld theory

Operational Solution to the Nonlinear Klein-Gordon Equation

Supported by Grant SEP-CONACYT 220603, the first author was supported by SEP-PRODEP through the project UAM-PTC-630, the third author was supported by Portuguese National Funds through the FCT Foundation for Science and Technology under the project PEst-UID/EEA/00066/2013We obtain solutions of the nonlinear Klein-Gordon equation using a novel operational method combined with the Adomian polynomial expansion of nonlinear functions. Our operational method does not use any integral transforms nor integration processes. We illustrate the application of our method by solving several examples and present numerical results that show the accuracy of the truncated series approximations to the solutions.authorsversionpublishe

Management of COVID-19 myopericarditis with reversal of cardiac dysfunction after blunting of cytokine storm: a case report.

Background:Coronavirus disease 2019 (COVID-19) is a syndrome that has been associated with multiple cardiac complications including myopericarditis. The pathophysiology and treatment for myopericarditis in the setting of COVID-19 infection is still under investigation. Case summary:We present a case of a 60-year-old male admitted for dyspnoea due to COVID-19. He developed new ST-segment elevation, elevated cardiac enzymes, severe left ventricular dysfunction, and high inflammatory markers in the setting of haemodynamic and respiratory collapse from the viral illness. He was diagnosed with COVID-19-induced myopericarditis. He showed rapid clinical improvement with a rapid wean off pressure support, resolution of electrocardiogram (ECG) findings, and recovery of left ventricular systolic function following treatment with intravenous immunoglobulin (IVIG) and methylprednisolone. Discussion:COVID-19\u27s complex and devastating complications continue to create new challenges for clinicians. Cardiac complications, specifically, have been shown to be a signal for worse prognosis in these patients. IVIG and steroids can inhibit the inflammatory cascade and decrease myocardial injury, with implications in treatment of severe myopericarditis

Birkhoff's theorem in the f(T) gravity

Generalized from the so-called teleparallel gravity which is exactly equivalent to general relativity, the $f(T)$ gravity has been proposed as an alternative gravity model to account for the dark energy phenomena. In this letter we prove that the external vacuum gravitational field for a spherically symmetric distribution of source matter in the $f(T)$ gravity framework must be static and the conclusion is independent of the radial distribution and spherically symmetric motion of the source matter that is, whether it is in motion or static. As a consequence, the Birkhoff's theorem is valid in the general $f(T)$ theory. We also discuss its application in the de Sitter space-time evolution phase as preferred to by the nowadays dark energy observations.Comment: 5p

F(T) gravity and k-essence

Modified teleparallel gravity theory with the torsion scalar have recently gained a lot of attention as a possible explanation of dark energy. We perform a thorough reconstruction analysis on the so-called $F(T)$ models, where $F(T)$ is some general function of the torsion term, and derive conditions for the equivalence between of $F(T)$ models with purely kinetic k-essence. We present a new class models of $F(T)$-gravity and k-essence. We also proposed some new models of generalized gases and knot universes as well as some generalizations of $F(T)$ gravity.Comment: 25 page

Laparoscopic Sleeve Gastrectomy with partial antrectomy and omental patch

Alcoy Hospital, Clínica San Jorge, Alcoy, España, Al XI-lea Congres al Asociației Chirurgilor „Nicolae Anestiadi” din Republica Moldova și cea de-a XXXIII-a Reuniune a Chirurgilor din Moldova „Iacomi-Răzeșu” 27-30 septembrie 2011Introducere: Sleeve Gastrectomia laparoscopică (LSG), în ciuda popularității sale, nu este o tehnică standardizată. Rezultatele pe termen lung sunt variabile, iar motivele controversate sunt: 1) Volumul tubului gastric residual; 2) Metoda de protecție a liniei de sutură a regiunei esofagogastrice pentru a preveni o eventuală scurgere; 3) Efectuarea unei antrumectomii parțiale. Începând din 1997 am folosit o sutură sero-seroasă invaginantă în peste 1200 de LSG izolate sau asociate cu Duodenal Switch (laparotomic sau laparoscopic) pentru a acoperi zona de sutură. Gagner a descris procedeul în anul 2000.Background: Laparoscopic Sleeve Gastrectomy (LSG) is, even if popular, a non-standardized bariatric technique. The results varied and there are controversial issues such as: 1) Size of the sleeve; 2) Protection against esophageal-gastric junction (EGJ) leaks; 3) The use of partial antrectomy. We have always used, since 1997, in more than 1200 isolated or combined open or laparoscopic Duodenal Switch (LDS) a continue inverting Lembert-type sero-serosa suture to cover the staple-line. Gagner reported the first operation in 2000

Extended Birkhoff's Theorem in the f(T) Gravity

The f(T) theory, a generally modified teleparallel gravity, has been proposed as an alternative gravity model to account for the dark energy phenomena. Following our previous work [Xin-he Meng and Ying-bin Wang, EPJC(2011), arXiv:1107.0629v1], we prove that the Birkhoff's theorem holds in a more general context, specifically with the off diagonal tetrad case, in this communication letter. Then, we discuss respectively the results of the external vacuum and internal gravitational field in the f(T) gravity framework, as well as the extended meaning of this theorem. We also investigate the validity of the Birkhoff's theorem in the frame of f(T) gravity via conformal transformation by regarding the Brans-Dicke-like scalar as effective matter, and study the equivalence between both Einstein frame and Jordan frame.Comment: 7 pages, 1 figure, submitted to EPJ-C. arXiv admin note: substantial text overlap with arXiv:1107.062

Eficiencia energética de fachadas ventiladas con baldosas cerámicas reflectantes al infrarrojo cercano

The growing social awareness with regard to sustainable construction and energy efficiency in buildings is leading specifications writers and end users to take into account new construction solutions. However, the introduction of these construction solutions into the market is slow and difficult owing to the limitations of the recognised thermal simulation tools, which do not allow estimations to be made when integrating innovative systems, and to the difficulty of validating their efficiency in actual buildings before marketing them. The present study analyses the energy efficiency of a ventilated façade made up of near-infrared reflective ceramic tiles, by integrating a mathematical model validated in the CIES Living Lab experimental building in Castellón into the EnergyPlus program.La creciente concienciación social respecto a la construcción sostenible y el ahorro energético en edificios está conduciendo a prescriptores y usuarios finales a tomar en consideración nuevas soluciones constructivas. Sin embargo, su introducción en el mercado es lenta y difícil, debido tanto a las limitaciones de las herramientas reconocidas de simulación térmica, que no permiten efectuar estimaciones integrando sistemas innovadores, como a la dificultad para validar su eficiencia en edificios reales previamente a su comercialización. En el presente trabajo se analiza la eficiencia energética de una fachada ventilada resuelta con baldosas cerámicas reflectantes al infrarrojo cercano, mediante la integración en el programa EnergyPlus de un modelo matemático que ha sido validado en el edificio experimental CIES Living Lab de Castellón

Statin pretreatment diminishes the levels of myocardial ischemia markers not only in CABG

A response to Ege E, Dereli Y, Kurban S, Sarigul A: Atorvastatin pretreatment diminishes the levels of myocardial ischemia markers early after CABG operation: an observational study. J Cardiothorac Surg 2010, 5:60

Birkhoff's Theorem in f(T) Gravity up to the Perturbative Order

f(T) gravity, a generally modified teleparallel gravity, has become very popular in recent times as it is able to reproduce the unification of inflation and late-time acceleration without the need of a dark energy component or an inflation field. In this present work, we investigate specifically the range of validity of Birkhoff's theorem with the general tetrad field via perturbative approach. At zero order, Birkhoff's theorem is valid and the solution is the well known Schwarzschild-(A)dS metric. Then considering the special case of the diagonal tetrad field, we present a new spherically symmetric solution in the frame of f(T) gravity up to the perturbative order. The results with the diagonal tetrad field satisfy the physical equivalence between the Jordan and the so-called Einstein frames, which are realized via conformal transformation, at least up to the first perturbative order.Comment: 8 pages, no figure. Final version, accepted for publication in EPJ