3,085 research outputs found
Spontaneous symmetry breaking, and strings defects in hypercomplex gauge field theories
Inspired by the appearance of split-complex structures in the dimensional
reduction of string theory, and in the theories emerging as byproducts, we
study the hyper-complex formulation of Abelian gauge field theories, by
incorporating a new complex unit to the usual complex one. The hypercomplex
version of the traditional Mexican hat potential associated with the
gauge field theory, corresponds to a {\it hybrid} potential with two real
components, and with as symmetry group. Each component
corresponds to a deformation of the hat potential, with the appearance of a new
degenerate vacuum. Hypercomplex electrodynamics will show novel properties,
such as the spontaneous symmetry breaking scenarios with running masses for the
vectorial and scalar Higgs fields, and the Aharonov-Bohm type strings defects
as exact solutions; these topological defects may be detected only by quantum
interference of charged particles through gauge invariant loop integrals. In a
particular limit, the {\it hyperbolic} electrodynamics does not admit
topological defects associated with continuous symmetriesComment: 40 page
INTUBACI 3N OROTRAQUEAL CON AIRTRAQ VERSUS LARINGOSCOPIA CONVENCIONAL EN PACIENTES CON OBESIDAD TIPO I PROGRAMADOS PARA CIRUG\ucdA ELECTIVA.
El presente estudio tuvo como objetivo comparar la eficacia de la intubaci\uf3n orotraqueal con laringoscopia Airtraq versus laringoscopia convencional en pacientes con obesidad tipo I programados para cirug\ueda electiva. Se realiz\uf3 un estudio tipo ensayo cl\uednico controlado simple ciego, la muestra estuvo conformada por 55 pacientes distribuidos aleatoriamente en 25 pacientes intubados con laringoscopio Airtraq y 30 intubados con laringoscopio Macintosh. El promedio de edad fue de 31,73 \ub1 7,07 a\uf1os, con predominio del sexo femenino, con \uedndice de masa corporal promedio de 31.06\ub12,56 para el grupo de Airtraq y de 33,1\ub12,43 para el grupo de Macintosh. La cirug\ueda m\ue1s frecuente en ambos grupos fue la Colecistectom\ueda Laparosc\uf3pica, clasificaci\uf3n de Mallampati grado II. El tiempo de intubaci\uf3n promedio fue de 17,97\ub113,04 minutos para pacientes que utilizaron Airtraq y 13,04\ub11,19 minutos para el grupo de Macintosh. La necesidad de asistencia para la intubaci\uf3n endotraqueal fue por retracci\uf3n del labio (36,7%) y alineaci\uf3n manual de la glotis (3,3%) para los pacientes con Macintosh. Del grupo de Airtraq\uae 28% requiri\uf3 de 2 intentos. No se observaron variaciones en los par\ue1metros hemodin\ue1micos en los diferentes momentos y 16,7% present\uf3 lesi\uf3n de v\ueda a\ue9rea como complicaci\uf3n en el grupo Macintosh. Para el \uedndice de intubaci\uf3n dif\uedcil se report\uf3 68% y 63,3% como f\ue1cil para los grupos Airtraq\uae y Macintosh respectivamente. En conclusi\uf3n, ambos laringoscopio representa una herramienta a \ufatil para los pacientes obesos; sin embargo, el resultado final depender\ue1 de las caracter\uedsticas del paciente, la disponibilidad de equipos, y la destreza y habilidades del operador.PALABRAS CLAVES DEL AUTOR: V\ueda a\ue9rea. Obesidad. Cirug\ueda ambulatoria. (DeCS: Bireme, Lilasc).ABSTRACTOROTRACHEAL INTUBATION WITH AIRTRAQ VERSUS CONVENTIONAL LARYNGOSCOPY IN OBESE TYPE I PATIENTS SCHEDULED FOR ELECTIVE SURGERY.
The objective of this study was to compare the efficiency in orotracheal intubation using Airtraq versus conventional laryngoscopy in obese type I patients scheduled for elective surgery. A single blind controlled clinical trial study was conducted, the sample was comprised of 55 patients randomly distributed in 25 patients using Airtraq laryngoscope and 30 using McIntosh laryngoscope. The mean age was 31.73 \ub1 7.07 years, female gender was predominant; the average body mass index was 31.06\ub12.56 for the Airtraq group and 33.1\ub12.43 for the McIntosh group. Additionally the most frequent surgery performed in both groups was laparoscopic cholecystectomy and Mallampati classification was Grade II. Average intubation time was 17.97\ub113.04 minutes for patients who used Airtraq and 13, 04\ub11, 19 minutes for the Macintosh group. The need for assistance for endotracheal intubation was by retraction of the lip (36.7%) and manual alignment of the glottis (3.3%) for patients with Macintosh. At the same time, 28% of the Airtraq group required 2 attempts. There were no variations in hemodynamic parameters at any stage and 16.7% had injury of the airways as a complication in the Macintosh group. The difficult intubation rate reported was 68% and 63.3%, respectively, in both Airtraq and Macintosh groups. In conclusion, both laryngoscopes represent a useful tool for obese patients; however, the final result will depend on the characteristics of the patient, equipment availability, and the dexterity and skill of the operator.KEY WORDS: Airway. Obesity. Ambulatory Surgical Procedures. (DeCS: NLM, Pubmed).<br
Determinación por cromatografía de aminoácidos en Iridaea ciliata e lridaea laminarioides
Se estudió el contenido de aminoácidos libres y de aquellos provenientes de hidro/izados de proteínas en Iridaea ciliata e lridaea laminarioides, por cromatografía en papel y en placas de celulosa. La composición de aminoácidos en ambas algas es muy similar. Los aminoácidos glicina, alanina, arginina, ácido glutámico y ácido aspártico son los que se encuentran en mayor proporción
Strong, lightweight, and recoverable three-dimensional ceramic nanolattices
Ceramics have some of the highest strength- and stiffness-to-weight ratios of any material but are suboptimal for use as structural materials because of their brittleness and sensitivity to flaws. We demonstrate the creation of structural metamaterials composed of nanoscale ceramics that are simultaneously ultralight, strong, and energy-absorbing and can recover their original shape after compressions in excess of 50% strain. Hollow-tube alumina nanolattices were fabricated using two-photon lithography, atomic layer deposition, and oxygen plasma etching. Structures were made with wall thicknesses of 5 to 60 nanometers and densities of 6.3 to 258 kilograms per cubic meter. Compression experiments revealed that optimizing the wall thickness-to-radius ratio of the tubes can suppress brittle fracture in the constituent solid in favor of elastic shell buckling, resulting in ductile-like deformation and recoverability
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