627 resultados para Silicone hydrogel contact lenses
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As part of the workshop in lenses to graphic arts-photography
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Introducción. Los Contact Center son una tendencia global que cada vez se impone más en nuestro país, y el estrés es un factor común ligado a sus trabajadores alrededor del mundo. Materiales y métodos. Este estudio de corte transversal, evalúo desde tres perspectivas el estrés buscando hallar la prevalencia de estresores laborales y síntomas de estrés en 440 trabajadores de un Contac Center en Bogotá en el 2015, a través de la realización de las encuestas JCQ (Job Content Questionnaire), ERI (Effort Reward Imbalance Questionaire), y Cuestionario para la Evaluación del Estrés (Ministerio de Protección Social) comparando los hallazgos entre el grupo de operadores que usan y los que no usan el audífono en diadema. Resultados. La prevalencia total de estrés bajo fue del 13%, muy bajo del 83,8% y 3,2% no reportaron síntomas de estrés. No se encontraron niveles de estrés medio o alto. En las prevalencias de estrés según el uso de la diadema, se encontró un nivel bajo de estrés en el 25% de los que usan diadema, muy bajo en el 68% y 6,5% no presentaron síntomas de estrés; por el contrario, el grupo que no usa la diadema presento sólo el 1% de estrés bajo y el 99% de estrés muy bajo, no hubo participantes que no reportaran estrés. Estresores laborales como la autoridad de decisión y la percepción de recompensa variaron en ambos grupos. El riesgo al usar la diadema de tener un nivel de estrés bajo fue del OR 2,32 IC95%(1,56-6,09), mostrando que al usar la diadema se tiene un doble de riesgo de bajo estrés en trabajadores operativos de Contact Center frente a presentar un estrés muy bajo. Conclusiones. La prevalencia de estrés general fue baja en ambos grupos evaluados. Las mujeres, los jóvenes y participantes estrato 2 y 3 fueron los grupos predominantes. Hay dos veces mayor riesgo al usar la diadema de tener estrés bajo en trabajadores operativos. Se recomienda mayor seguimiento por parte de los Contac center a los estresores y síntomas de estrés a los que están expuestos sus trabajadores por lo que se requiere promover más estudios que sirvan de soporte para evaluar la diadema como factor estresor laboral.
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Crédito común para Secundaria Obligatoria en el cual se pretende profundizar en las estructuras idiomáticas propias para presentarse a uno mismo, y a otras personas, e introducir elementos de la realidad francesa en el contexto educativo de los alumnos. Se proponen 9 grupos de actividades de aprendizaje destinadas a potenciar los siguientes aspectos: comprensión de la lengua del profesor, participación dinámica en la clase, contactar con la realidad francesa, apropiación de la lengua, reconocimento de la lengua oral en el texto escrito y viceversa, y reconocimiento de elementos fonéticos y prosódicos en la lengua oral.
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Resumen tomado de la publicación. Monográfico con el título: Competencias básicas en el marco de la convergencia europea
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A number of recent experiments suggest that, at a given wetting speed, the dynamic contact angle formed by an advancing liquid-gas interface with a solid substrate depends on the flow field and geometry near the moving contact line. In the present work, this effect is investigated in the framework of an earlier developed theory that was based on the fact that dynamic wetting is, by its very name, a process of formation of a new liquid-solid interface (newly “wetted” solid surface) and hence should be considered not as a singular problem but as a particular case from a general class of flows with forming or/and disappearing interfaces. The results demonstrate that, in the flow configuration of curtain coating, where a liquid sheet (“curtain”) impinges onto a moving solid substrate, the actual dynamic contact angle indeed depends not only on the wetting speed and material constants of the contacting media, as in the so-called slip models, but also on the inlet velocity of the curtain, its height, and the angle between the falling curtain and the solid surface. In other words, for the same wetting speed the dynamic contact angle can be varied by manipulating the flow field and geometry near the moving contact line. The obtained results have important experimental implications: given that the dynamic contact angle is determined by the values of the surface tensions at the contact line and hence depends on the distributions of the surface parameters along the interfaces, which can be influenced by the flow field, one can use the overall flow conditions and the contact angle as a macroscopic multiparametric signal-response pair that probes the dynamics of the liquid-solid interface. This approach would allow one to investigate experimentally such properties of the interface as, for example, its equation of state and the rheological properties involved in the interface’s response to an external torque, and would help to measure its parameters, such as the coefficient of sliding friction, the surface-tension relaxation time, and so on.
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Multilayered hydrogel coatings can be developed on the surface of glass slides via layer-by-layer deposition of hydrogen-bonded interpolymer complexes formed by poly(acrylic acid) and methylcellulose. Chemical modification of the glass surface with (3-aminopropyl)triethoxysilane with subsequent layer-by-layer deposition and cross-linking of interpolymer complexes by thermal treatment allows fabrication of ultrathin hydrogel coatings, not detachable from the substrate. The thickness of these coatings is directly related to the number of deposition cycles and cross-linking conditions. An unusual dependence of the hydrogel swelling properties on the sample thickness is observed and can be interpreted by gradual transitions between two- and three-dimensional networks. The hydrogels exhibit pH-responsive swelling behaviour, achieving higher swelling degrees at pH > 6.0. These coatings can be used as model substrates to study the adhesive properties of pharmaceutical tablets and can potentially mimic the total work of adhesion observed for the detachment of mucoadhesives from porcine buccal mucosa but fail to exhibit identical detachment profiles.
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Purpose. Some children with visual stress and/or headaches have fewer symptoms when wearing colored lenses. Although subjective reports of improved perception exist, few objective correlates of these effects have been established. Methods. In a pilot study, 10 children who wore Intuitive Colorimeter lenses, and claimed benefit, and two asymptomatic children were tested. Steady-state potentials were measured in response to low contrast patterns modulating at a frequency of 12 Hz. Four viewing conditions were compared: 1) no lens; 2) Colorimeter lens; 3) lens of complementary color; and 4) spectrally neutral lens with similar photopic transmission. Results. The asymptomatic children showed little or no difference between the lens and no lens conditions. When all the symptomatic children were tested together, a similar result was found. However, when the symptomatic children were divided into two groups depending on their symptoms, an interaction emerged. Children with visual stress but no headaches showed the largest amplitude visual evoked potential response in the no lens condition, whereas those children whose symptoms included severe headaches or migraine showed the largest amplitude visual evoked potential response when wearing their prescribed lens. Conclusions. The results suggest that it is possible to measure objective correlates of the beneficial subjective perceptual effects of colored lenses, at least in some children who have a history of migraine or severe headaches.
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The self-assembly and hydrogelation properties of two Fmoc-tripeptides [Fmoc = N-(fluorenyl-9-methoxycarbonyl)] are investigated, in borate buffer and other basic solutions. A remarkable difference in self-assembly properties is observed comparing Fmoc-VLK(Boc) with Fmoc-K(Boc)LV, both containing K protected by N(epsilon)-tert-butyloxycarbonate (Boc). In borate buffer, the former peptide forms highly anisotropic fibrils which show local alignment, and the hydrogels show flow-aligning properties. In contrast, Fmoc-K(Boc)LV forms highly branched fibrils that produce isotropic hydrogels with a much higher modulus (G' > 10(4) Pa), and lower concentration for hydrogel formation. The distinct self-assembled structures are ascribed to conformational differences, as revealed by secondary structure probes (CD, FTIR, Raman spectroscopy) and X-ray diffraction. Fmoc-VLK(Boc) forms well-defined beta-sheets with a cross-beta X-ray diffraction pattern, whereas Fmoc-KLV(Boc) forms unoriented assemblies with multiple stacked sheets. Interchange of the K and V residues when inverting the tripeptide sequence thus leads to substantial differences in self-assembled structures, suggesting a promising approach to control hydrogel properties.