On extension of multi-parametric local semigroups of isometric operators and some applications

Universidad Central de Venezuela, Consejo de Desarrollo Científico y Humanístico. Subvención PI-03-8623-2013/2It is shown that, under certain uniqueness conditions, a strongly continuous n-parametric local semigroup of isometric operators on a Hilbert space, can be extended to a strongly continuous n-parametric group of unitary operators on a larger Hilbert space. As an application a proof of the G.I. Èskin multi-dimensional version of the M.GK ̇rei ̆n ex- tension theorem, for positive definite functions, is given.peerReviewe

On extension of multi-parametric local semigroups of isometric operators and some applications

Universidad Central de Venezuela, Consejo de Desarrollo Científico y Humanístico. Subvención PI-03-8623-2013/2It is shown that, under certain uniqueness conditions, a strongly continuous n-parametric local semigroup of isometric operators on a Hilbert space, can be extended to a strongly continuous n-parametric group of unitary operators on a larger Hilbert space. As an application a proof of the G.I. Èskin multi-dimensional version of the M.GK ̇rei ̆n ex- tension theorem, for positive definite functions, is given.peerReviewe

Transformation Optics Approach to Plasmon-Exciton Strong Coupling in Nanocavities

We investigate the conditions yielding plasmon-exciton strong coupling at the single emitter level in the gap between two metal nanoparticles. A quasi-analytical transformation optics approach is developed that makes possible a thorough exploration of this hybrid system incorporating the full richness of its plasmonic spectrum. This allows us to reveal that by placing the emitter away from the cavity center, its coupling to multipolar dark modes of both even and odd parity increases remarkably. This way, reversible dynamics in the population of the quantum emitter takes place in feasible implementations of this archetypal nanocavity.Comment: 5 pages, 4 figure

La visualizacion y el aprendizaje colaborativo en la enseñanza de fracciones

La presente investigación se realizó en una escuela primaria pública del sur de México y tuvo como objetivo valorar las estrategias de recuperación de los conocimientos previos, la visualización y el trabajo colaborativo en la construcción del concepto fracciones. El enfoque metodológico fue el cualitativo en el que participaron 18 alumnos de grupo del sexto grado y su maestra. Se encontró que las estrategias de recuperación de los conocimientos previos, la visualización y el trabajo colaborativo favorecieron a que los alumnos construyeran el concepto de fracciones desde una perspectiva amplia. Esto es, los alumnos identificaron a los números racionales en situaciones tales como: relación parte-todo de un entero, cociente, medida, y proporción

Documentation of model components EXPAMOD and CAPRI

ISBN no.: 978-90-8585-129-

Broadband telecom transparency of semiconductor-coated metal nanowires: more transparent than glass

Metallic nanowires (NW) coated with a high permittivity dielectric are proposed as means to strongly reduce the light scattering of the conducting NW, rendering them transparent at infrared wavelengths of interest in telecommunications. Based on a simple, universal law derived from electrostatics arguments, we find appropriate parameters to reduce the scattering efficiency of hybrid metal-dielectric NW by up to three orders of magnitude as compared with the scattering efficiency of the homogeneous metallic NW. We show that metal@dielectric structures are much more robust against fabrication imperfections than analogous dielectric@metal ones. The bandwidth of the transparent region entirely covers the near IR telecommunications range. Although this effect is optimum at normal incidence and for a given polarization, rigorous theoretical and numerical calculations reveal that transparency is robust against changes in polarization and angle of incidence, and also holds for relatively dense periodic or random arrangements. A wealth of applications based on metal-NWs may benefit from such invisibility

Estructuras conceptuales tridimensionales. Auxiliares en el aprendizaje de la química

Hasta ahora, el uso de mapas conceptuales constituye una valiosa experiencia didáctica, pudiéndose aplicar en todas las fases del proceso educativo. En el ámbito del aprendizaje, ha demostrado ser un instrumento eficaz para el logro del conocimiento. Sin embargo, existen algunos problemas a solucionar para lograr el uso correcto de los mapas conceptuales, puesto que muchas construcciones tienden a ser más descriptivas que explicativas. Con el propósito de facilitar el aprendizaje de los estudiantes de Química de la carrera de Ingeniería Química, se diseñaron y construyeron mapas conceptuales tridimensionales que permitiesen superar las deficiencias de conectores inadecuados o exceso de conceptos en un mapa bidimensional. Se presentan las estructuras obtenidas y los comentarios de los estudiantes

Unidad de diagnóstico rápido (UDR) en patología tumoral

Objetivos: Desarrollar una UDR, vinculada al Servicio de Urgencias Hospitalario (SUH), proporcionando prioridad en el radiodiagnóstico y mayor accesibilidad a las consultas de especializada, supone un abordaje de la patología tumoral más dinámico. Nuestro objetivo fue analizar el impacto de la UDR en el manejo de dicha patología. Metodología: Estudio descriptivo, retrospectivo, de base poblacional, realizado en la Clínica USP-Palmaplanas, hospital de 150 camas Analizando el manejo del total de pacientes con tumores atendidos en la UDR desde abril 2006 a marzo 2008. Se utilizaron los indicadores de actividad y calidad creados para dicho fin. Resultados: Total pacientes atendidos en la UDR 2473, total pacientes con diagnóstico de patología tumoral 73. Tiempo de espera desde su atención en el SUH hasta valoración en la UDR (<48h 41%, 2-4 días 36%), tiempo de espera desde atención inicial- final en las UDR (mismo día 17%, <8 días 64%), tiempo de espera desde alta UDR hasta su atención para el abordaje terapéutico (<48h en el 91%), se cursaron 11 ingresos hospitalarios tras el diagnóstico desde la UDR. Conclusiones: La UDR permite agilizar el diagnóstico y tratamiento precoces de la patología tumoral, mejorando claramente la eficiencia y la seguridad con una reducción en la estancia media hospitalaria y en la carga emocional del paciente.Objectives: The implementation of a Hospital Emergency Unit based RDU in order to prioritise diagnostic imaging and the access to specialised outpatient clinics, has dynamized the management of patients first diagnosed with cancer. Our objective was to analyze the impact of an RDU in the management of this group of patients. Methods: Descriptive, retrospective study of the population seen at USP Palmaplanas Clinic, a 150 bed hospital, which analyses the management of patients seen in the RDU from April 2006 to March 2008. Activity and quality indicators were created to support this study. Results: Total number of patients seen in the RDU: 2473. 73 of these patients were diagnosed with possible cancer. Waiting times to be seen in RDU from the Emergency Unit: <48 hours in 41% of the cases, 2-4 days in 36%. Waiting times from first visit at RDU to last visit: same day in 17%, <8 days in 64%. Waiting times from first visit to RDU to treatment: <48 hours in 91% of the cases. 11 patients were admitted to hospital for management. Discussion: RDU allows a dynamic management of patients with cancer, from first diagnosis to early treatment, improving patient care, efficiency and safety. It also reduces hospital stay and reduces patients’ emotional distress

Periodic very high energy γ -Ray Emission from LS I +61◦303 Observed with the magic telescope

The MAGIC collaboration has recently reported the discovery of γ -ray emission from the binary system LS I +61◦303 in the TeV energy region. Here we present new observational results on this source in the energy range between 300 GeV and 3 TeV. In total, 112 hr of data were taken between 2006 September and December covering four orbital cycles of this object. This large amount of data allowed us to produce an integral flux light curve covering for the first time all orbital phases of LS I +61◦303. In addition, we also obtained a differential energy spectrum for two orbital phase bins covering the phase range 0.5 < φ < 0.6 and 0.6 < φ < 0.7. The photon index in the two phase bins is consistent within the errors with an average index Γ = 2.6±0.2stat ±0.2sys. LS I +61◦303 was found to be variable at TeV energies on timescales of days. These new MAGIC measurements allowed us to search for intranight variability of the very high energy emission; however, no evidence for flux variability on timescales down to 30 min was found. To test for possible periodic structures in the light curve, we apply the formalism developed by Lomb and Scargle to the LS I +61◦303 data taken in 2005 and 2006. We found the LS I +61◦303 data set to be periodic with a period of (26.8 ± 0.2) days (with a post-trial chance probability of 10−7), close to the orbital period.Peer reviewe