La formación de conceptos en la resolución numérica de ecuaciones no lineales

Un estudiante no necesariamente utiliza la definición cuando decide si un objeto matemático es ejemplo o contraejemplo de un concepto determinado, sino que generalmente toma la decisión basándose en una imagen que se hizo del mismo. Por lo tanto, es aconsejable comenzar la enseñanza de cada concepto presentando diversos ejemplos mediante los cuales los alumnos puedan formarse una adecuada imagen. Este trabajo tiene como objetivo presentar la secuencia didáctica que se diseñó para la comprensión de los conceptos que se hallan involucrados en la resolución numérica de ecuaciones no lineales, ofreciendo experiencias y ejemplos. También se mostrarán los resultados obtenidos tras su aplicación

Female breakfast skippers display a disrupted cortisol rhythm and elevated blood pressure

Chronic stress and over-activity in the hypothalamic–pituitary–adrenal (HPA) axis may link breakfast skipping and poor cardiometabolic health. Missing the first major meal of the day in rodents prolongs elevated circulating corticosterone at a time when it\u27s normally decreasing. To extend these findings to humans, we hypothesized that habitual breakfast skippers would display a similar pattern of circulating cortisol and alterations in meal and stress-induced cortisol reactions. Normal weight to obese women aged 18–45 years old who were strictly defined as either breakfast skippers (n = 30) or breakfast eaters (n = 35) were invited to participate in our study. Normal breakfast habits were maintained for the entire study period and each participant attended 4 lab visits. Over the first 2 lab visits, body composition, fasting clinical chemistries, and self-reports of chronic stress were assessed. On each of 2 additional days (lab visits 3 and 4), salivary free cortisol was measured at home upon waking and at bedtime, and in the lab in response to a standard lunch, ad libitum afternoon snack buffet, and stress and control (relaxation) tasks. The order of the control and stress test visits was randomized. While body weight, body composition, HOMA-IR, total and HDL cholesterol did not statistically differ (p N 0.05), both diastolic and systolic blood pressure was elevated (p b 0.01) and LDL cholesterol was lower (p = 0.04) in the breakfast skipper group. Compared to the breakfast eaters and on the control task visit only, breakfast skippers had higher circulating cortisol from arrival to midafternoon (p b 0.01) and during the snack buffet (p b 0.05). Furthermore, the lunch-induced cortisol reaction was larger in the ‘skippers’ (p = 0.03). On both stress and control visit days, the diurnal cortisol amplitude was significantly (p = 0.02) blunted in breakfast skippers. Self-reports of chronic stress did not differ between the groups. These data indicate that habitually skip- ping breakfast is associated with stress-independent over-activity in the HPA axis which, if prolonged, may increase risk (e.g., hypertension) for cardiometabolic disease in some people

Entornos virtuales: un nuevo escenario para el aprendizaje del análisis numérico

En la actualidad, las instituciones de nivel superior enfrentan el desafío de desarrollar en los alumnos la alfabetización digital necesaria para la utilización competente de las herramientas tecnológicas. Una alternativa para promover dicha alfabetización digital es el uso de los entornos virtuales de aprendizaje. En este contexto, el Grupo Ingeniería & Educación ha diseñado una plataforma virtual y diversos sitios para ser utilizados en las clases de Análisis Numérico de la Facultad Regional San Nicolás como complemento de las clases presenciales. Este artículo tiene como objetivo mostrar estos entornos virtuales, que se utilizan en función de los estilos de aprendizajes de los alumnos

Uso de objetos de aprendizaje como facilitadores de la comprensión de los métodos numéricos para resolver problemas de valor inicial

Los estudiantes de carreras de ingeniería deben adquirir habilidades y destrezas para resolver, en forma exacta o aproximada, problemas que involucran ecuaciones diferenciales, dado que éstas usualmente modelizan problemas ingenieriles. En los cursos de Análisis Numérico de la Facultad Regional San Nicolás se han detectado inconvenientes en el aprendizaje de métodos numéricos para resolver problemas de valor inicial. Para superar estas dificultades, se han elaborado aplicaciones que implementan los métodos numéricos estudiados para ser utilizadas durante el desarrollo de las clases. En este trabajo se muestran las aplicaciones diseñadas en Mathematica, en formato CDF, junto con algunas de las actividades que se les presentó a los estudiantes durante el aprendizaje del tema. Para medir el impacto de estas herramientas en el proceso de comprensión de los alumnos, se aplicó una encuesta donde debían determinar en qué grado los CDFs utilizados los ayudó a comprender los distintos conceptos matemáticos involucrados

Digitalización de imágenes del microscopio electrónico de barrido HITACHI HHS-2R

El Laboratorio de Microscopia Aplicada a Estudios Moleculares y Celulares (LAMAE) de la FIUNER, posee un Microscopio Electrónico de Barrido (M.E.B) marca Hitachi, Modelo HHS-2R. Este equipo es del año 1978, y se encuentra en muy buenas condiciones de funcionamiento, pero posee un sistema de registro de imágenes obsoleto que limita drásticamente su utilización. El presente trabajo tiene como objetivo principal actualizar el sistema de video analógico  y reemplazar el sistema  original de  fotografía tipo polaroid, por un sistema de digitalización, captura y almacenamiento digital de imágenes. Además como objetivo secundario y no menos importante se propone diseñar e implementar un sistema que simule las señales de video no convencional presentes en el M.E.B para luego ser usado en lugar de éste durante la fase experimental y de validación del sistema de digitalización de imágenes. Por lo expresado anteriormente, el  trabajo realizado se divide en dos tareas principales: el desarrollo del sistema de digitalización de imágenes del microscopio y el desarrollo del sistema que permita realizar las pruebas sobre la placa digitalizadora

Increased risk of preterm delivery with high cortisol during pregnancy is modified by fetal sex : a cohort study

Background: Previous studies show an association between maternal plasma and salivary cortisol and preterm birth but have been primarily conducted in high-income countries. It is unknown whether salivary cortisol is a risk factor for preterm birth in Ghana. Our objective was to determine whether maternal salivary cortisol during pregnancy was associated with pregnancy duration and preterm delivery in Ghana. Methods: We conducted a cohort study of 783 pregnant women in Ghana. We measured salivary cortisol at baseline (mean 16 wk), 28 wk., and 36 wk. gestation. Pregnancy duration was determined primarily by ultrasound. We used adjusted linear regression models to examine the association between cortisol and pregnancy duration and Poisson regression models to determine the risk of preterm delivery among women with high cortisol at baseline or 28 wk. gestation. Results: Mean pregnancy duration was 39.4 ± 1.8 wk. and 6.6% had a preterm delivery. Mean maternal cortisol increased throughout pregnancy, from 4.9 ± 2.7 nmol/L at baseline (16 wk) to 6.4 ± 3.2 nmol/L at 28 wk. and 7.9 ± 3.0 nmol/L at 36 wk. gestation. In adjusted analyses, higher cortisol concentrations at baseline (β = − 0.39, p =.002) and 28 wk. (β = − 0.49, p =.001), but not 36 wk. (β = − 0.23, p =.084) were associated with a shorter pregnancy duration. Women with high cortisol at baseline (> 6.3 nmol/L) had an increased relative risk of preterm delivery (RR (95% CI): 1.96 (1.13, 3.40)), but the association between high cortisol at 28 wk. and preterm delivery was not significant. There was a significant interaction with fetal sex (p-for-interaction = 0.037): among women carrying male fetuses, high cortisol at baseline increased the risk of preterm delivery threefold (3.18 (1.51, 6.71)) while there was no association (1.17 (0.50, 2.74)) among women carrying female fetuses. Conclusion: Higher maternal cortisol is associated with a shorter pregnancy duration and an increased risk of preterm delivery. Subgroup analysis by fetal sex revealed that this association is evident primarily among women carrying male fetuses. Future studies of cortisol and preterm delivery should include consideration of fetal sex as a potential effect modifier.publishedVersionPeer reviewe

DESIGN, DEVELOPMENT AND CHARACTERIZATION OF AN EXTREMELY LOWFREQUENCY ELECTROMAGNETIC FIELDS GENERATOR

In this article we present the results of the design, development and characterization of an extremely low frequency electromagnetic fields generator to carry out experiments with small animals. For the design of the exposure system, we took into account that its configuration should allow the application of a electromagnetic fields that meets uniformityand field intensity criteria, while making it possible to observe, manipulate and locate the sample easily, a fact that proposes accessibility requirements. For the application of different electromagnetic fields exposure protocols in the future, the generator must allow calibrated and homogeneous emissions, under known exposure conditions. Results of the constructive process are presented, in which the proposed materials and methods are analyzed, as well as the system performance results

Diseño, desarrollo y caracterización de un generador de CEM de frecuencia extremadamente baja para el trabajo con pequeños animales

En este trabajo presentamos los resultados del diseño, desarrollo y caracterización de un generador de Campos Electromagnéticos de Frecuencia Extremadamente Baja CEM-FEB para la realización de experimentos con pequeños animales. Para el diseño del sistema de exposición se tuvo como premisa que la configuración permita aplicar a la muestra un CEM que cumpla con criterios de uniformidad e intensidad de campo requeridos pero que además haga posible observar, manipular y ubicar la muestra fácilmente, lo cual impone requisitos de accesibilidad. Para la aplicación futura de distintos protocolos de exposición a CEM, el generador debe permitir realizar emisiones calibradas y homogéneas, bajo condiciones de exposición conocidas. Se presentan resultados del proceso constructivo, en los que se analizan materiales y métodos propuestos, así como de estudios de desempeño del sistema. Al final del trabajo se presentan los resultados de una prueba piloto trabajando con pequeños animales expuestos a CEM-FEB

Examining techniques for measuring the effects of nutrients on mental performance and mood state

Purpose: Intake of specific nutrients has been linked to mental states and various indices of cognitive performance although the effects are often subtle and difficult to interpret. Measurement of so-called objective variables (e.g. reaction times) is often considered to be the gold standard for assessing outcomes in this field of research. It can, however, be argued that data on subjective experience (e.g. mood) are also important and may enrich existing objective data. The aim of this review is to evaluate methods for measuring mental performance and mood, considering the definition of subjective mood and the validity of measures of subjective experience. Methods: A multi-stakeholder expert group was invited by ILSI Europe to come to a consensus around the utility of objective and subjective measurement in this field, which forms the basis of the paper. Therefore, the present review reflects a succinct overview of the science but is not intended to be a systematic review. Results: The proposed approach extends the traditional methodology using standard ‘objective’ measurements to also include the consumers’ subjective experiences in relation to food. Specific recommendations include 1) using contemporary methods to capture transient mood states; 2) using sufficiently sensitive measures to capture effects of nutritional intervention; 3) considering the possibility that subjective and objective responses will occur over different time frames; and 4) recognition of the importance of expectancy and placebo effects for subjective measures. Conclusions: The consensus reached was that the most informative approach should involve collection and consideration of both objective and subjective data