Energy transfer in two-wave mixing quasi-degenerated in photorefractive crystals

Wave equations describing the quasi-degenerated two-beam coupling in the photorefractive crystals for high frequency gratings have been solved. In the case of the quasi-degenerate two-beam coupling, equations depend upon the coupling coefficient, the response time of the medium, the input beams frequencies, the absorption coefficient and the input intensity ratio. The response time of the medium is function of the diffusion field, the drift field, the saturation field and the concentration ratio, i.e., the ratio between NA density of acceptor impurities and ND density of donor impurities. The effect of these parameters on the gain has been studied in details.Facultad de Ciencias Exacta

Energy transfer in two-wave mixing quasi-degenerated in photorefractive crystals

Wave equations describing the quasi-degenerated two-beam coupling in the photorefractive crystals for high frequency gratings have been solved. In the case of the quasi-degenerate two-beam coupling, equations depend upon the coupling coefficient, the response time of the medium, the input beams frequencies, the absorption coefficient and the input intensity ratio. The response time of the medium is function of the diffusion field, the drift field, the saturation field and the concentration ratio, i.e., the ratio between NA density of acceptor impurities and ND density of donor impurities. The effect of these parameters on the gain has been studied in details.Facultad de Ciencias Exacta

Relevancia del E-commerce para el sector confecciones de la ciudad de Pereira

El presente documento establece una propuesta para tratar de determinar cuál es la importancia que tiene el E-commerce para el mejoramiento de la comercialización de productos en el sector confecciones de la ciudad de Pereira; teniendo como objetivo general analizar la relevancia que tiene el E-Commerce para el desarrollo comercial del sector confecciones de la ciudad de Pereira. Con el análisis de información de carácter primario y secundario, se podrá establecer si esta novedosa tendencia basada en las TIC, es una estrategia fundamental para que las empresas del mencionado sector mejoren sus resultados comerciales. Luego del desarrollo de la investigación, se permite exponer que el E-commerce aprueba replantear los objetivos en la empresa con un claro direccionamiento estratégico, facilitando crear nuevos productos y mercados, diferentes canales de distribución, reducir el coste de las actividades empresariales y favorecer la apertura de nuevos mercados (Fernández, 2015). Cabe resaltar que el E-commerce está teniendo un papel importante en las empresas y es fundamental para la globalización, ya que tiene un alcance con los clientes a nivel mundial y no solamente local. La necesidad de llevar un mercado nacional al exterior, convirtió al comercio electrónico en una herramienta favorable para las empresas, obteniendo de esta forma un crecimiento para la comercialización; llevando a la constitución de entidades para promover, regular y controlar el comercio electrónico. En Colombia se constituyó la entidad CCCE Cámara Colombiana de Comercio Electrónico (Mazuera, 2012). Las empresas que lo implementan logran tener ventajas competitivas frente al comercio tradicional; su inversión se basa en la creación de programas, redes y sistemas que permiten dar a conocer un bien y/o producto al mundo. Lo anterior reafirma la intención de la presente investigación, ya que ella proporciona a los empresarios del sector un conocimeinto más a fondo sobre los elementos que les puede brindar

La familia huilense y el cuidado de la salud: una estrategia para el mantenimiento de la salud familiar

Esta investigación implementó una estrategia piloto para el mantenimiento de la salud basada en el enfoque sistémico dentro del enfoque de la promoción y prevención que plantea la Ley de Segundad Social en Salud para la atención integral de la familia. El estudio se desarrolló en tres fases: inicialmente se realizó una fase cuantitativa-descriptiva en los municipios de Neiva, Pitalito, Garzón, La Plata y Baraya, así como una cualitativa con grupos focales a partir de las categorías teóricas. Del análisis de la información cualitativa surgieron las categorías inductivas centrales: concepto salud-enfermedad; percepción salud enfermedad; prácticas en salud; percepción de instituciones y profesionales de la salud; responsabilidad del cuidado de la salud en la familia. Con las categorías se construyó la estrategia de mantenimiento en salud de la familia huilense (tercera fase del estudio), la intervención se desarrolló en Neiva, mediante la ejecución de una estrategia piloto basada en el conversatorio reflexivo terapéutico bajo el contexto de la promoción de la salud, que permitió establecer lo que podría ser una alternativa para el cuidado integral de la salud de la familia

Effects of the Implementation of Tutored Learning Projects and Formative and Shared Assessment Systems in Pre-Service Teacher Education

The main purpose of Formative and Shared Assessment (F&SA) is to improve student learning, to improve and redirect teaching practice and to improve the teaching-learning process. This research has two objectives: (1) to analyse the results of the applicability and difficulty of the Good Practice of Tutored Learning Projects (TLP) in a Pre-service Teacher Education (PTE) subject; and (2) to examine the advantages and disadvantages of the F&SA system used in the same subject. For this purpose, a longitudinal study of a PTE subject is carried out over three academic years. The instruments used to collect information are: a structured report on Good Practice in university teaching and an anonymous questionnaire for students to evaluate the experience of Good Practice, which has been carried out and the subject’s evaluation system. The results show the consistency of the course design over the years. Students are satisfied with the TLP experience because they consider it to be useful, effective, innovative, replicable and sustainable, as well as helping in the acquisition of competences

Schistosomus reflexus en un canino: reporte caso

Durante la realización de una cesárea en el Centro de Medicina Veterinaria y Zootecnia de la Universidad CES se encontró un neonato de la raza Bull Terrier con signos de Schistosomus reflexus, una alteración congénita en la formación de la pared abdominal con exposición de las vísceras. El cachorro del presente reporte nació con vida y se realizó la corrección quirúrgica de la agenesia de la pared abdominal, procedimiento que le permitió su supervivencia por una semana más. El artículo describe el caso clínico de este neonato que según lo reporta la literatura, es el segundo caso de Schistosomus reflexus en un canino

The role of the family in deceased organ procurement: A guide for Clinitians and Policymakers

Families play an essential role in deceased organ procurement. As the person cannot directly communicate his or her wishes regarding donation, the family is often the only source of information regarding consent or refusal. We provide a systematic description and analysis of the different roles the family can play, and actions the family can take, in the organ procurement process across different jurisdictions and consent systems. First, families can inform or update healthcare professionals about a person’s donation wishes. Second, families can authorize organ procurement in the absence of deceased’s preferences and the default is not to remove organs, and oppose donation where there is no evidence of preference but the default is to presume consent; in both cases, the decision could be based on their own wishes or what they think the deceased would have wanted. Finally, families can overrule the known wishes of the deceased, which can mean preventing donation, or permitting donation when the deceased refused it. We propose a schema of 4 levels on which to map these possible family roles: no role, witness, surrogate, and full decisional authority. We conclude by mapping different jurisdictions onto this schema to provide a more comprehensive understanding of the consent system for organ donation and some important nuances about the role of families. This classificatory model aims to account for the majority of the world’s consent systems. It provides conceptual and methodological guidance that can be useful to researchers, professionals, and policymakers involved in organ procurement

Carboxymethyl cellulose coated magnetic nanoparticles transport across a human lung microvascular endothelial cell model of the blood–brain barrier

Sustained and safe delivery of therapeutic agents across the blood–brain barrier (BBB) is one of the major challenges for the treatment of neurological disorders as this barrier limits the ability of most drug molecules to reach the brain. Targeted delivery of the drugs used to treat these disorders could potentially offer a considerable reduction of the common side effects of their treatment. The preparation and characterization of carboxymethyl cellulose (CMC) coated magnetic nanoparticles (Fe3O4@CMC) is reported as an alternative that meets the need for novel therapies capable of crossing the BBB. In vitro assays were used to evaluate the ability of these polysaccharide coated biocompatible, water-soluble, magnetic nanoparticles to deliver drug therapy across a model of the BBB. As a drug model, dopamine hydrochloride loading and release profiles in physiological solution were determined using UV-Vis spectroscopy. Cell viability tests in Human Lung Microvascular Endothelial (HLMVE) cell cultures showed no significant cell death, morphological changes or alterations in mitochondrial function after 24 and 48 h of exposure to the nanoparticles. Evidence of nanoparticle interactions and nanoparticle uptake by the cell membrane was obtained by electron microscopy (SEM and TEM) analyses. Permeability through a BBB model (the transwell assay) was evaluated to assess the ability of Fe3O4@CMC nanoparticles to be transported across a densely packed HLMVE cell barrier. The results suggest that these nanoparticles can be useful drug transport and release systems for the design of novel pharmaceutical agents for brain therapy