Aportaciones a la autodid??ctica de la F??sica

El plan general del trabajo consiste en hacer expl??citas y comparar, con rigurosidad cient??fica, los m??todos de ense??anza que impl??citamente preocupa a todo profesor cuando trata de comunicar a sus alumnos la materia que imparte, en este caso la f??sica. Probar la efectividad de la Ense??anza Programada de F??sica a nivel universitario, compar??ndola con la tradicional. Se sigue el Sistema de Skinner de Ense??anza Programada y toda la investigaci??n se lleva a cabo durante dos cursos acad??micos teniendo como referencia 400 alumnos. A un grupo de alumnos de primer curso de la Secci??n de F??sica se les imparti?? un temario de F??sica por el m??todo de la ense??anza tradicional durante dos cursos; y el mismo temario, previamente elaborado, a otro grupo de la misma secci??n, tambi??n durante los mismos cursos por el m??todo de la Ense??anza Programada. Ambos grupos, y en ambos cursos fueron elegidos al azar comprobando, antes del experimento, que ambas muestras pertenec??an a la poblaci??n total, y que eran homog??neos intelectual y ps??quicamente. Se cont?? con la ayuda de la Ciencia Psicol??gica y Estad??stica. Se han medido ciertos factores de la inteligencia y de la personalidad del alumno que se cree tienen que ver con el aprendizaje de la F??sica. En base a esto se han preparado textos programados de F??sica General a nivel del primer curso de Ciencias F??sicas. Se ha probado que el valor de las correlaciones obtenidas, para las muestras tomadas, se puede extender a la poblaci??n, calculando los errores muestrales y los intervalos de confianza correspondientes. Se elige al azar dos muestras homog??neas intelecual y psiqu??camente de entre la poblaci??n estudiantil de F??sica y a cada una de ellas se les imparti?? un tipo de ense??anza distinto. Despu??s de aplicar la Teor??a Estad??stica de la significaci??n de la diferencia de medios en los dos tipos de ense??anza y resultados de este estudio di?? un 't' de student significativo, lo que demuestra que la ense??anza programada, ha dado mejor resultado en el aprendizaje de la f??sica general del primer curso de Facultad que la ense??anza tradicional.

Speech intelligibility in noise-induced hearing loss: effects of high-frequency compensation

This dissertation examines the frequency response that results in the maximum level of speech intelligibility for persons with noise-induced hearing loss.

La problemática de la violencia escolar en los 7mos años de Básica de: la Escuela Fiscal “Ángel Isaac Chiriboga” y del “Pensionado “San Vicente” de la ciudad de Quito. Año lectivo 2012-2013

Esta investigación científica tiene como objetivo analizar y comparar las estrategias pedagógicas, y el tipo de comunicación desarrollados en los 7mos Años de las escuelas: “Ángel Isaac Chiriboga” y Pensionado “San Vicente” de Quito. 2012- 2013; en el primer quinquemestre; a través de, la aplicación de guías de observación de clase para conocer el tipo de estrategias pedagógicas desarrolladas en el proceso de enseñanza-aprendizaje y el uso de encuestas a los/as alumnos/as para identificar la clase de interacción que existe entre alumno-maestro y alumno-alumno. De esta manera, reconocer los factores que contribuyen a generar la violencia escolar y brindar recomendaciones alternativas, que propicien la disminución de la violencia escolar. De hecho, este trabajo consta de la Introducción que contiene: planteamiento del problema, pregunta central de la investigación, propósito de la investigación, justificación, objetivos: general, específicos, antecedentes legales, alcances, limitaciones y metodología que guía el trabajo y tipo de fuentes. El Capítulo I aborda el Marco Contextual (descripción física y organización: funcional y estructural de la escuela). El Capítulo II describe al Marco Conceptual de: conceptualización básica de violencia, agresión, características y Teorías del Aprendizaje: Conductistas (Watson- Pavlo, Skinner), Cognoscitivas (Piaget, Vigotzky), y por Modelación (Bandura) y de la Inteligencia Emocional, (Goleman) El Capítulo III contiene el Marco Empírico que consiste en el análisis e interpretación de la información. Finalmente, constarán las conclusiones, recomendaciones, bibliografía y anexos.

Relationships between Duck and Grassland Bird Relative Abundance and Species Richness in Southern Saskatchewan

Digital map products that integrate long-term duck population and land-use data are currently being used to guide conservation program delivery on the Canadian Prairies. However, understanding the inter-relationships between ducks and other grassland bird species would greatly enhance program planning and delivery. We hypothesized that ducks, and Northern Pintail (Anas acuta) in particular, may function as an umbrella guild for the overall breeding habitat quality for other grassland bird species. We compared grassland bird species richness and relative abundance among areas of low, moderate, and high predicted waterfowl breeding densities (i.e., duck density strata) in the southern Missouri Coteau, Saskatchewan. We conducted roadside point counts and delineated habitats within a 400 m radius of each point. The duck high-density stratum supported greater avian species richness and abundance than did the duck low-density stratum. Overall, duck and other grassland bird species richness and abundance were moderately correlated, with all r between 0.37 and 0.69 (all P < 0.05). Although the habitat requirements of Northern Pintail may overlap with those of other grassland endemics, priority grassland bird species richness was only moderately correlated with total pintail abundance in both years, and the abundances of pintail and grassland songbirds listed by the Committee on the Status of Endangered Wildlife in Canada were not correlated. No differences in the mean number of priority grassland species were detected among the strata. Adequate critical habitat for several priority species may not be protected if conservation is focused only in areas of moderate to high wetland density because large tracts of contiguous, dry grassland habitat (e.g., pasture) occur infrequently in high-quality duck habitat.

The Representative Soil Sampling Scheme of England and Wales: a statistical analysis of topsoil nutrient status and pH between 1971 and 2001

The Representative Soil Sampling Scheme of England and Wales has recorded information on the soil of agricultural land in England and Wales since 1969. It is a valuable source of information about the soil in the context of monitoring for sustainable agricultural development. Changes in soil nutrient status and pH were examined over the period 1971-2001. Several methods of statistical analysis were applied to data from the surveys during this period. The main focus here is on the data for 1971, 1981, 1991 and 2001. The results of examining change over time in general show that levels of potassium in the soil have increased, those of magnesium have remained fairly constant, those of phosphorus have declined and pH has changed little. Future sampling needs have been assessed in the context of monitoring, to determine the mean at a given level of confidence and tolerable error and to detect change in the mean over time at these same levels over periods of 5 and 10 years. The results of a non-hierarchical multivariate classification suggest that England and Wales could be stratified to optimize future sampling and analysis. To monitor soil quality and health more generally than for agriculture, more of the country should be sampled and a wider range of properties recorded.

A jackknife variance estimator for unequal probability sampling

The jackknife method is often used for variance estimation in sample surveys but has only been developed for a limited class of sampling designs.We propose a jackknife variance estimator which is defined for any without-replacement unequal probability sampling design. We demonstrate design consistency of this estimator for a broad class of point estimators. A Monte Carlo study shows how the proposed estimator may improve on existing estimators.

Educational and psychosocial programmes for adolescents with diabetes: approaches, outcomes and cost-effectiveness

Diabetes incurs heavy personal and health system costs. Self-management is required if complications are to be avoided. Adolescents face particular challenges as they learn to take responsibility for their diabetes. A systematic review of educational and psychosocial programmes for adolescents with diabetes was undertaken. This aimed to: identify and categorise the types of programmes that have been evaluated; assess the cost-effectiveness of interventions; identify areas where further research is required. Sixty-two papers were identified and Subjected to a narrative review. Generic programmes focus on knowledge/skills, psychosocial issues, and behaviour/self-management. They result in modest improvements across a range of outcomes but improvements are often not sustained, suggesting a need for continuous support, possibly integrated into normal care. In-hospital education at diagnosis confers few advantages over home treatment. The greatest returns may be obtained by targeting poorly controlled individuals. Few studies addressed resourcing issues and robust cost-effectiveness appraisals are required to identify interventions that generate the greatest returns on expenditure. (C) 2004 Elsevier Ireland Ltd. All rights reserved.

Physiological and proteomic approaches to address heat tolerance during anthesis in rice (Oryza sativa L.)

Episodes of high temperature at anthesis, which in rice is the most sensitive stage to temperature, are expected to occur more frequently in future climates. The morphology of the reproductive organs and pollen number, and changes in anther protein expression, were studied in response to high temperature at anthesis in three rice (Oryza sativa L.) genotypes. Plants were exposed to 6 h of high (38 °C) and control (29 °C) temperature at anthesis and spikelets collected for morphological and proteomic analysis. Moroberekan was the most heat-sensitive genotype (18% spikelet fertility at 38 °C), while IR64 (48%) and N22 (71%) were moderately and highly heat tolerant, respectively. There were significant differences among the genotypes in anther length and width, apical and basal pore lengths, apical pore area, and stigma and pistil length. Temperature also affected some of these traits, increasing anther pore size and reducing stigma length. Nonetheless, variation in the number of pollen on the stigma could not be related to measured morphological traits. Variation in spikelet fertility was highly correlated (r=0.97, n=6) with the proportion of spikelets with ≥20 germinated pollen grains on the stigma. A 2D-gel electrophoresis showed 46 protein spots changing in abundance, of which 13 differentially expressed protein spots were analysed by MS/MALDI-TOF. A cold and a heat shock protein were found significantly up-regulated in N22, and this may have contributed to the greater heat tolerance of N22. The role of differentially expressed proteins and morphology during anther dehiscence and pollination in shaping heat tolerance and susceptibility is discussed.

In vitro micro-tuber initiation and dormancy in yam

Dormancy is a mechanism that regulates the timing of sprouting (germination) of affected plant parts as well as ensures that the food quality of edible parts is maintained in storage until the following growing season. In yam, however, little is known about the control of tuber initiation or tuber dormancy. The objective of this study was to determine the effects of selected plant growth regulators (PGRs) on tuber initiation and dormancy, using an in vitro system. In two replicated experiments, 2-chloroethylphosphonic acid (ethephon, an ethylene source), abscisic acid (ABA) and gibberellin (GA3) – and their inhibitors silver nitrate, fluridone and 2-chloroethyl-trimethylammonium chloride, respectively – were added at two concentrations to the culture medium prior to explant culture. Dates of micro-tuber initiation and sprouting (end of dormancy) and tuber number were recorded. In the control (no PGR) in Experiment 1, micro-tubers were initiated at the base of the stem after 176 days and sprouted 235 days later, that is 411 days after culturing. Most PGR treatments had only small effects (±30 days) on the duration of dormancy and the time of micro-tuber initiation. However, in GA3 micro-tuber initiation occurred after 76 days, about 100 days earlier than in the control, whereas fluridone affected the position of micro-tubers and duration of dormancy. With fluridone treatments, tubers were found at the base of the stem (normal position) and on lower and upper nodes. Lower node tubers sprouted within 225 days of culturing compared with about 420 days after culturing at other nodal positions and in other PGR treatments. These data suggest an important role for ABA and gibberellic acid in yam micro-tuber initiation and the induction of dormancy.

Genetic analysis of heat tolerance at anthesis in rice

Genetic analysis of heat tolerance will help breeders produce rice (Oryza sativa L.) varieties adapted to future climates. An F6 population of 181 recombinant inbred lines of Bala (tolerant) × Azucena (susceptible) was screened for heat tolerance at anthesis by measuring spikelet fertility at 30°C (control) and 38°C (high temperature) in experiments conducted in the Philippines and the United Kingdom. The parents varied significantly for absolute spikelet fertility under control (79–87%) and at high temperature (2.9–47.1%), and for relative spikelet fertility (high temperature/control) at high temperature (3.7–54.9%). There was no correlation between spikelet fertility in control and high-temperature conditions and no common quantitative trait loci (QTLs) were identified. Two QTLs for spikelet fertility under control conditions were identified on chromosomes 2 and 4. Eight QTLs for spikelet fertility under high-temperature conditions were identified on chromosomes 1, 2, 3, 8, 10, and 11. The most significant heat-responsive QTL, contributed by Bala and explaining up to 18% of the phenotypic variation, was identified on chromosome 1 (38.35 mega base pairs on the rice physical genome map). This QTL was also found to influence plant height, explaining 36.6% of the phenotypic variation. A comparison with other studies of abiotic (drought, cold, salinity) stresses showed QTLs at similar positions on chromosomes 1, 3, 8, and 10, suggesting common underlying stress-responsive regions of the genome.

The effect of dietary nitrate on salivary, plasma, and urinary nitrate metabolism in humans

Dietary nitrate is metabolized to nitrite by bacterial flora on the posterior surface of the tongue leading to increased salivary nitrite concentrations. In the acidic environment of the stomach, nitrite forms nitrous acid, a potent nitrating/nitrosating agent. The aim of this study was to examine the pharmacokinetics of dietary nitrate in relation to the formation of salivary, plasma, and urinary nitrite and nitrate in healthy subjects. A secondary aim was to determine whether dietary nitrate increases the formation of protein-bound 3-nitrotyrosine in plasma, and if dietary nitrate improves platelet function. The pharmacokinetic profile of urinary nitrate excretion indicates total clearance of consumed nitrate in a 24 h period. While urinary, salivary, and plasma nitrate concentrations increased between 4- and 7-fold, a significant increase in nitrite was only detected in saliva (7-fold). High dietary nitrate consumption does not cause a significant acute change in plasma concentrations of 3-nitrotyrosine or in platelet function.