What is a scientific experiment?: The impact of a professional development course on teachers’ ability to design an inquiry-based science curriculum

Designing inquiry-based science lessons can be a challenge for secondary school teachers. In this study we evaluated the development of in-service teachers’ lesson plans as they took part in a 10-month professional development course in Peru which engaged teachers in the design of inquiry-based lessons. At the beginning, most teachers designed either confirmatory or structured inquiry activities. As the course progressed, however, they started designing guided and open inquiry lesson plans. We found four factors that accounted for this change: re-evaluating the need for lab materials, revising their views on the nature of science, engaging in guided and open inquiry activities themselves, and trying out inquiry-based lessons with their own students. Our results point to the importance of engaging teachers in prolonged and varied opportunities for inquiry as part of teacher education programs in order to achieve the challenge of changing teachers’ views and practices in science education.Fil: Pérez, María del Carmen B.. Universidad de Piura; PerúFil: Furman, Melina Gabriela. Universidad de San Andrés. Escuela de Educación; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; Argentin

Saturated hydrocarbon content in olive fruits and crude olive pomace oils

40 Páginas; 14 Tablas; 5 FigurasOlive fruits contain an n-alkane series of saturated hydrocarbons mainly in the pulp. Lower amounts of a complex mixture of paraffins, unresolved by gas chromatography (UCM – unresolved complex mixture), have been found in cuticle, stone (woody shell and seed), olive leaves, and talc used as an aid to olive oil extraction. The amounts of both kinds of hydrocarbons are related to the olive cultivar and are transferred to oils in a proportion depending on the oil-obtaining process (centrifugation or solvent extraction). In olive oil obtained by centrifugation, only n-alkanes were detected. However, in olive oil extracted by second centrifugation, small amounts of UCM paraffins were detected together with the n-alkanes. Olive pomace oils showed a very variable content of both types of hydrocarbons according to the different obtaining process, such as double centrifugation, solvent extraction or centrifugation followed by solvent extraction. ‘White mineral oil’ used in oil extraction machinery is the source of the high concentrations of UCM paraffins found in some olive and olive pomace oils. In the case of second centrifugation olive oil, a maximum limit of 50 mg kg−1 of UCM is suggested, whereas in the case of crude olive pomace oil, it amounts to 250 mg kg−1 plus an additional minimum of 1.0 for the n-alkanes/UCM ratio.The technical expertise of Mrs Rosario González Cordones is acknowledged for her assistance in the laboratory. This work was supported by a grant of the Spanish Ministry of Agriculture, Food, and EnvironmentPeer reviewe

Impact of Olive Extract Addition on Corn Starch-Based Active Edible Films Properties for Food Packaging Applications

Active edible films based on corn starch containing glycerol as a plasticizer and an olive extract obtained from Spanish olive fruit (Olea europaea) by-products (olive extract; OE) at different concentrations (0, 0.05, 0.1 and 0.2 wt%) were prepared by using the casting technique and further solvent-evaporation. OE showed high total phenolic and flavonoids contents and antioxidant activity, which was evaluated by using three different methods: free radical scavenging assay by (1, 1-Dipheny l-2-picrylhydrazyl) DPPH, 2, 2-Azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) ABTS radical inhibition and ferric reducing antioxidant power (FRAP). The incorporation of OE into the corn starch/glycerol matrix underlined the antioxidant potential and antimicrobial effect against E. coli and S. aureus of these novel active films, being noticeable for films added with 0.2 wt% OE. The developed active films showed a clear thermo-oxidative stability improvement with OE incorporation, in particular at 0.2 wt% loading with an increase of around 50 °C in the initial degradation temperature (Tini) and oxidation onset temperature (OOT). The functional properties of control films were also improved with OE addition resulting in a decrease in Young´s modulus, elongation at break, shore D hardness and water vapor permeability. The present work suggested the potential of the developed corn starch-based edible films as low-price and sustainable food packaging systems to prevent the oxidative deterioration of packaged foodstuff while reducing also the generation of olive by-products

Una experiencia de universidades Iberoamericanas que estudian las dificultades de los estudiantes universitarios en los cursos introductorios de física

Los estudios realizados por siete universidades iberoamericanas constituyen un claro ejemplo del trabajo en redes. El mismo ha consistido en determinar tanto el conocimiento conceptual como algunas habilidades básicas de ingresantes a la universidad en carreras de Ciencias e Ingeniería. El diagnóstico indaga en lo conceptual sobre temas de cinemática lineal, fuerzas, energía, circuitos eléctricos resistivos y fuerza eléctrica. En lo procedimental se estudia el reconocimiento de una hipótesis de trabajo, identificación de las variables en un fenómeno físico, control de variables en un experimento, interpretación de datos experimentales en forma de tabla o gráfico, entre otros. Las preguntas de las dos pruebas fueron seleccionadas de tests utilizadas en reconocidos trabajos científicos.La investigación es cuasi experimental con pruebas iguales de pre y postest. Para esta presentación se han elegido los resultados obtenidos en el periodo 2006-2008. Los resultados del pretest, de ambas pruebas, son bajos y revelan que los estudiantes tienen conocimientos conceptuales y procedimentales muy pobres. Estos datos alertan sobre las dificultades que tienen estos alumnos en los cursos introductorios universitarios de Física, donde se supone familiaridad con estos conocimientos básicos. Los resultados posinstrucción corroboran esa predicción e indican que los estudiantes no han alcanzado los niveles deseados en las dimensiones investigadas. Los problemas son similares en las diferentes universidades.Los datos alertan sobre la necesidad de desarrollar estrategias de enseñanza en la universidad que involucren a los estudiantes en la participación activa de sus propios procesos de formación para tratar de revertir estos resultados

Addresing schemes generation for multiplexed AFLC displays with color, gray scale and video rate capability

4 pages, 10 figures, 1 table.-- Contributed to: 3ª Reunión Española de Optoelectrónica (OPTOEL'03), Leganés, Madrid, Jul 14-16, 2003.In the last years, fiat liquid crystal displays (LCD) have experienced a great spreading, both in its applications as in its manufacturing technology. Ferroelectric Liquid Crystals (FLCs) is the technology on which the research has been mainly focused.This work was partially supported by the Spanish Ministry of Science and Technology, grant no. TIC2000-1594-C02-02.Publicad

Dietary modifications engaged in young muslims of Ramadan fasting

La práctica del precepto islámico del Ramadán (R), impone a las personas que lo practican importantes modificaciones fisiológicas y psicológicas debido a las restricciones hídricas y dietéticas a las que se ven sometidos, lo que tiene una especial repercusión en el rendimiento físico e intelectual de los estudiantes musulmanes, particularmente en sociedades multiculturales de tipo occidental, en las que no se producen ajustes horarios, en las actividades diarias. Entre las modificaciones introducidas en los hábitos de vida, por esta causa, destacan los cambios dietéticos, tanto cualitativos como cuantitativos. Por la relevancia de la cuestión y ante el escaso conocimiento de los efectos del Ramadán en estudiantes adolescentes que viven en sociedades no islámicas, se plantea como objetivo de este estudio, el análisis de las modificaciones en macronutrientes, ocurridas durante el R, en un grupo de alumnos musulmanes de ambos sexos, con el fin de solucionar y prevenir algunos de los problemas que se plantean en este periodo. Material y método: Se seleccionaron 55 jóvenes musulmanes (24 hombres y 31 mujeres) con edades comprendidas entre 15 y 18 años, que realizan el R y se analizó la dieta mediante inventario de 3 días, una semana antes del ayuno y en la segunda semana durante éste. Resultados: En el R, no hay cambios significativos en la ingesta calórica de los hombres y sí en el de las mujeres. Se incrementa el consumo de carbohidratos y proteínas y desciende el de grasas. Discusión: Los cambios en R conducen a una dieta más ajustada a las recomendaciones nutricionales, y a esto parece haber contribuido el hecho de que los participantes llevaron a cabo sus comidas en el seno doméstico donde, a pesar del corte occidental de la población, se deja sentir una importante influencia de las tradiciones y hábitos magrebíes, por el contacto fronterizo con Marruecos.The practice of the Islamic precept of Ramadan (R) imposes to those who practice it important physiological and psychological changes due to the water and dietary restrictions they are subjected to, which has a particular impact on the Muslim students’ physical and psychological performances, particularly in multicultural Western societies, where there are no schedule adjustments in daily activities. Among the changes in lifestyle, consequently, the dietary changes are stressed, both qualitative and quantitative. Due to the importance of this issue and facing the limited knowledge the Muslim teenagers who live in non-Islamic societies have about the effects of Ramadan, it is suggested as main objective of this study the analysis of changes in nutrients during R in a group of Muslim students of both sexes, in order to solve and prevent some of the problems shown in this period. Materials and methods: 55 Muslim youngsters were selected (24 men and 31 women) aged between 15 and 18, who practise R; and the diet was analysed by inventory over 3 days, one week before fasting and in the second week during it. Results: In R there are no relevant changes in caloric intake. The consumption of carbohydrates and proteins is increased, and that of fat is decreased. Discussion: the changes in R lead to a diet more regulated to nutritional recommendations; and to this seems to have contributed the fact that the participants took their meals at home, where, in spite of the Western cut of the population, it is felt an important influence of North African traditions and habits, due to its border contact with Morocco

Mentiras contagiosas. Guía para esquivar la desinformación en salud

Internet y las redes sociales han democratizado la comunicación de contenidos sobre salud y han multiplicado la difusión pública de informaciones relacionadas con ese tema. Muchas de las informaciones sanitarias proceden de fuentes acreditadas y son plenamente solventes, lo que permite a la ciudadanía acceder fácilmente a información de calidad que promueve comportamientos responsables. Sin embargo, al mismo tiempo, en las redes circulan cada vez más contenidos sobre salud de procedencia desconocida y fiabilidad dudosa. Buena parte de esos mensajes son, de hecho, intencionadamente engañosos. Las redes, en definitiva, son una moneda de dos caras: dan acceso a contenidos sanitarios de calidad, pero exponen asimismo a la ciudadanía a diversos riesgos. Esta guía pretende desarrollar y divulgar pautas que sirvan para contrarrestar el fenómeno de la desinformación en materia de salud

Displays and Photonics Application Group activities

Displays and Photonics Application Group (GDAF) is devoted to design and development of passive and active devices and sensors for their applications in WDM networks, CWDM, POP, and RF over fiber networks using different technologies such as optical fibers, liquid crystals, and integrated optics. The group is also very active in modeling, electrooptical characterization, and addressing electronics of LCDs. In this article we are going to describe the main activities carried out in the group.Publicad