The Casimir Effect for Parallel Plates Revisited

The Casimir effect for a massless scalar field with Dirichlet and periodic boundary conditions (b.c.) on infinite parallel plates is revisited in the local quantum field theory (lqft) framework introduced by B.Kay. The model displays a number of more realistic features than the ones he treated. In addition to local observables, as the energy density, we propose to consider intensive variables, such as the energy per unit area $\epsilon$, as fundamental observables. Adopting this view, lqft rejects Dirichlet (the same result may be proved for Neumann or mixed) b.c., and accepts periodic b.c.: in the former case $\epsilon$ diverges, in the latter it is finite, as is shown by an expression for the local energy density obtained from lqft through the use of the Poisson summation formula. Another way to see this uses methods from the Euler summation formula: in the proof of regularization independence of the energy per unit area, a regularization-dependent surface term arises upon use of Dirichlet b.c. but not periodic b.c.. For the conformally invariant scalar quantum field, this surface term is absent, due to the condition of zero trace of the energy momentum tensor, as remarked by B.De Witt. The latter property does not hold in tha application to the dark energy problem in Cosmology, in which we argue that periodic b.c. might play a distinguished role.Comment: 25 pages, no figures, late

The gauge theory of dislocations: static solutions of screw and edge dislocations

We investigate the T(3)-gauge theory of static dislocations in continuous solids. We use the most general linear constitutive relations bilinear in the elastic distortion tensor and dislocation density tensor for the force and pseudomoment stresses of an isotropic solid. The constitutive relations contain six material parameters. In this theory both the force and pseudomoment stresses are asymmetric. The theory possesses four characteristic lengths l1, l2, l3 and l4 which are given explicitely. We first derive the three-dimensional Green tensor of the master equation for the force stresses in the translational gauge theory of dislocations. We then investigate the situation of generalized plane strain (anti-plane strain and plane strain). Using the stress function method, we find modified stress functions for screw and edge dislocations. The solution of the screw dislocation is given in terms of one independent length l1=l4. For the problem of an edge dislocation, only two characteristic lengths l2 and l3 arise with one of them being the same l2=l1 as for the screw dislocation. Thus, this theory possesses only two independent lengths for generalized plane strain. If the two lengths l2 and l3 of an edge dislocation are equal, we obtain an edge dislocation which is the gauge theoretical version of a modified Volterra edge dislocation. In the case of symmetric stresses we recover well known results obtained earlier.Comment: 33 pages, 17 figure

Aislamientos de Histoplasma capsulatum con morfología aberrante obtenidos en la República Argentina Histoplasma capsulatum with aberrant morphology isolated in Argentina

Por primera vez en la Argentina se describe una cepa de Histoplasma capsulatum var. capsulatum con morfotipo aberrante, obtenida de un paciente con SIDA. En los primocultivos desarrollados en agar Sabouraud a 25-28 °C, las colonias de la fase micelial fueron blancas, glabras, umbilicadas, centralmente radiadas y de bordes regulares, más semejantes a las de hongos hialinos ambientales que a las de H. capsulatum. Al examen microscópico llamó la atención la ausencia de conidios característicos, la presencia de clamidoconidios solitarios, terminales e intercalares, de 4 µm de diámetro, y el engrosamiento de las hifas. La identificación del hongo se confirmó mediante la detección de exoantígenos específicos (H y M) en los sobrenadantes de cultivos de la fase micelial y por la reversión a la fase levaduriforme típica, obtenida al incubar en agar cerebro-corazón adicionado con cisteína a 37 °C. Mediante RAPD-PCR con los iniciadores 1281-1283, el perfil del ADN genómico coincidió con el genotipo de H. capsulatum predominante entre los aislamientos de pacientes argentinos.<br>For the first time in Argentina, we describe a strain of Histoplasma capsulatum var. capsulatum with an aberrant morphology that was isolated from a single patient with AIDS. Mycelial phase cultures on agar Sabouraud at 25-28 °C showed white, glabrous, umbilicated and centrally radiated colonies. Unusual microscopic findings were the absence of typical conidia, the presence of terminal/intercalary chlamydoconidia with a diameter of 4 µm and of thickened hyphae. Fungal identification was confirmed by the detection of bands H and M species specific antigens in mycelial culture supernatants and reversion to the typical yeast phase on agar brain-heart-cysteine at 37 °C. The genomic DNA profile obtained by RAPD-PCR with primers 1281-1283 coincided with the predominant profile of H.capsulatum among isolates from Argentine patients

Thoracoscopic repair of esophageal atresia with and without tracheoesophageal fistula Reparación toracoscópica de atresia esofágica con y sin fistula traqueoesofágica

© 2014, Sociedad Chilena de Pediatria. All rights reserved. Introduction: Esophageal atresia (EA) is the interruption of the continuity of the esophagus, with or without persistent communication with the trachea. Recent advances in surgical techniques have made possible correction with minimally invasive surgery (MIS). Objective: To evaluate the management of thoracoscopic technique in the treatment of EA. Patients and Method: Retrospective analysis of medical records in two centers was carried out between 2007 and 2012. Variables such as gestational age, gender, weight, type of esophageal atresia, malformations, surgery and postoperative complications were recorded. Results: Twenty patients, 15 of them with type III EA, 4 with type I and one unclassifiable, were part of the study. 13 patients underwent ligation, cut of tracheoesophageal fistula and end to end anastomosis. Two underwent laparoscopic gastrostomy and fistula ligation. One patient required conversion and underwent esopha

Transient fungemia caused by an amphotericin B-resistant isolate of Candida haemulonii

Fil: Rodero, Laura. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Cuenca-Estrella, Manuel. Instituto de Salud Carlos III. Servicio de Micología; España.Fil: Córdoba, Susana. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Cahn, Pedro. Hospital Fernández. Servicio de Infectología; Argentina.Fil: Davel, Graciela Odelsia. ANLIS Dr.C.G.Malbrán. Instituto Nacional de Enfermedades Infecciosas. Departamento de Micología; Argentina.Fil: Kaufman, Sara. Hospital Fernández. Servicio de Microbiología; Argentina.Fil: Guelfand, Liliana. Hospital Fernández. Servicio de Microbiología; Argentina.Fil: Rodríguez-Tudela, Juan L. Instituto de Salud Carlos III. Servicio de Micología; España.A bloodstream infection due to Candida haemulonii afflicting a patient with fever and a medical history of megaloblastic anemia is reported. The clinical isolate was misidentified by the API 20C and VITEK identification systems. The results of susceptibility tests showed that the MIC of amphotericin B for C. haemulonii was 4 g/ml. Additional susceptibility testing procedures based on the use of antibiotic medium 3 and Iso-Sensitest broth were performed, and killing curves were determined. Two collection strains of C. haemulonii were employed as controls. The three isolates exhibited resistance to amphotericin B in vitro regardless of the antifungal susceptibility testing method employed. In addition, the MICs of fluconazole for the three isolates were high. Further studies are needed in order to ascertain whether this species exhibits innate or acquired resistance to amphotericin B and other antifungal agents

Transient Fungemia Caused by an Amphotericin B-Resistant Isolate of Candida haemulonii

A bloodstream infection due to Candida haemulonii afflicting a patient with fever and a medical history of megaloblastic anemia is reported. The clinical isolate was misidentified by the API 20C and VITEK identification systems. The results of susceptibility tests showed that the MIC of amphotericin B for C. haemulonii was 4 μg/ml. Additional susceptibility testing procedures based on the use of antibiotic medium 3 and Iso-Sensitest broth were performed, and killing curves were determined. Two collection strains of C. haemulonii were employed as controls. The three isolates exhibited resistance to amphotericin B in vitro regardless of the antifungal susceptibility testing method employed. In addition, the MICs of fluconazole for the three isolates were high. Further studies are needed in order to ascertain whether this species exhibits innate or acquired resistance to amphotericin B and other antifungal agents