La aplicación de "chequeos" para evaluar habilidades de pensamiento crítico y superior en un curso universitario básico de electromagnetismo

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The thermoplastic techniques or single-cone technique on the quality of root canal filling with tricalcium silicate-based sealer : an integrative review

The filling of the root canal system (RCS) is an important step in endodontic treatment and aims to obtain a three-dimensional sealing of the root canal spaces to prevent bacterial contamination. For this, the selection of an appropriate sealer must be p

Enseñanza por competencias en la universidad: Un ejemplo del electromagnetismo básico

Higher education must be characterized for preparing its graduates as personal and professional competent citizens. Nevertheless, some general competences in higher education are not enough treated and they must be reinforced using active and cooperative learning. Physics teaching allows teachers design and guide activities that develop capacities and thinking skills, preparing students for applying them in daily opportunities. In this work it is presented a problematic situation referred to electric circuits and led to students belonged to a basic electromagnetism course of the second year of a Bachelor and Teaching Degree in Physics. The general objective is to promote, in this group of university students, competences to give an efficient solution to the stated situation.La Educación Superior debe caracterizarse por preparar a sus egresados como ciudadanos competentes personal y profesionalmente. No obstante, algunas competencias generales de la Educación Superior no se trabajan lo suficiente y deberían reforzarse utilizando el aprendizaje activo y cooperativo. La enseñanza de la Física permite al docente proyectar y guiar actividades que desarrollen capacidades y habilidades de pensamiento de los alumnos, que los prepare para aplicarlas en las oportunidades que se presentan en la vida cotidiana. En este trabajo se presenta una situación problemática, referida al tema circuitos eléctricos, y dirigida a alumnos de un curso básico de Electromagnetismo de segundo año de las carreras Profesorado y Licenciatura en Física. El objetivo general es el de promover, en el grupo de estudiantes universitarios, competencias para dar solución en forma eficaz a la situación planteada

Evaluation of the impact behaviour of AlSi10Mg alloy produced using laser additive manufacturing

In the present study, instrumented impact strength tests were carried out on Charpy AlSi10Mg samples produced using laser additive manufacturing in order to accurately investigate the influence of building directions, heat treatment parameters and also the effect of Hot Isostatic Pressing (HIP) on their impact properties. AlSi10Mg cast samples were also tested for comparison. In addition to metallographic inspections, a deep characterization of the fracture surfaces in all the analysed conditions was performed. Microstructural features were also correlated to the impact properties: absorbed energy, peak force, crack nucleation and propagation energies. It was found that additive manufactured samples in as-produced condition exhibit the best performance due to their peculiar microstructure. HIP, followed by T6 heat treatment, is positive for the alloy properties since it effectively reduces porosities, which are a favourable path for crack propagation. Building direction has a clear effect on the fracture propagation. Samples in as-produced condition display greater unevenness of the fracture surface in the horizontal direction than in the vertical direction. This trend is less evident after heat treatment, but still detectable. The fractal dimension of the fracture surfaces is a quantitative parameter sensitive to the building orientation of samples and to the performed heat treatments

Habilidades de pensamiento crítico y superior desarrolladas por un grupo de alumnos de carreras de Física universitaria: Resultados de entrevistas realizadas a sus docentes

This work shows the results obtained from the analysis of in-depth interviews carried on a group of students´ teachers of the Bachelor in Physics and Teaching Training in Physics, in the Faculty of Exact and Natural Science of the National University of La Pampa, Argentine. The methodology used is a generic case study in which the focus is set in teachers´ opinions about scientific thinking changes produced in students to which, an integrated teaching strategy, based in the practice of higher and critical thinking, was applied in a basic electromagnetism course. It is concluded that, in these students those skills have been promoted, in all the cognitive dominions as they show this capacity in all the courses after that in which the strategy was applied.En este trabajo se muestran los resultados obtenidos del análisis de entrevistas en profundidad efectuadas a docentes de un grupo de alumnos, de las carreras Licenciatura en Física y Profesorado en Física de la Facultad de Ciencias Exactas y Naturales de la Universidad Nacional de La Pampa, Argentina. La metodología empleada es un estudio de casos genérico en el cual el foco está puesto en las opiniones de los docentes acerca de los cambios en la forma de pensamiento científico del grupo de estudiantes al cual se aplicó, en un curso básico de electromagnetismo una estrategia de enseñanza integradora, basada en la práctica de habilidades de pensamiento crítico y superior. Se concluye que se ha promovido en estos estudiantes el desarrollo de dichas habilidades, en todos los niveles del dominio cognitivo, al poner ellos de manifiesto esta capacidad durante el cursado de la de totalidad de las asignaturas, posteriores a aquella donde se aplicó la estrategia

Aplicación de actividades para practicar habilidades de pensamiento crítico y superior en un curso universitario básico de electromagnetismo: algunos resultados

This work shows the results obtained in the implementation of actions ("checkings" and partial evaluation) which have been thought and elaborated by the teachers with the proposal of promoting in the students the possibility of developing a higher and critical thinking. The methodology used is a generic case study in which the sample is formed by all the assistant students to the Physics III course, of the Bachelor in Physics and Teaching Training in Physics, during the year 2007 in the Faculty of Exact and Natural Science of the National University of La Pampa, Argentine. It may be concluded that, the proposed actions to facilitate higher and critical thinking have promoted in this group of students a critical and reflexive learning, allowing them to integrate knowledge, to evaluate themselves and to be evaluated during the developing of the contends of "Electrostatic and magnetostatic fields related with their sources".En este trabajo se hace referencia a los resultados obtenidos de la aplicación de las acciones ("chequeos" y evaluación parcial) pensadas y elaboradas por los docentes, tendientes a favorecer en los estudiantes la posibilidad de desarrollar destrezas intelectuales del pensamiento superior y crítico. La metodología utilizada es un estudio de caso genérico en el que la muestra está constituida por la totalidad de los alumnos que cursaron la asignatura Física III en el año 2007 de las carreras Licenciatura en Física y Profesorado en Física de la Facultad de Ciencias Exactas y Naturales de la Universidad Nacional de La Pampa, Argentina. Se puede concluir que, las acciones propuestas como facilitadoras del pensamiento crítico y superior han promovido, en este grupo de alumnos un aprendizaje críticamente reflexivo y permitieron a los mismos integrar el conocimiento, autoevaluarse y ser evaluados durante el desarrollo del tema "Campos eléctricos y magnéticos relacionados con sus fuentes"

Prospective study of the meaning of indeterminate results of the Recombinant Immunoblot Assay for hepatitis C virus in blood donors

Background. The interpretation of "indeterminate" results of the recombinant immunoblot assay (RIBA) is a particularly sensitive issue for Transfusion Services, and donors with such a serological condition require long-term follow-up. Materials and methods. In the Immunohaematology and Transfusion Medicine Division of Umberto I University Hospital (Rome, Italy), 102,979 donor blood units were screened for hepatitis C virus (HCV) antibodies by enzyme-linked immunosorbent assay (ELISA) over a 5-year period (01.01.2000 - 31.12.2004). Since 24.10.2001, HCV-RNA testing was added. All samples repeatedly reactive by ELISA were then submitted to a HCV confirmatory assay (RIBA). Results. Among the 102,979 donors we found 271 positive to HCV ELISA testing. The results of the RIBA assay for these donors were negative in 178 (65.7%) cases, positive in 28 (10.3%) and indeterminate in 65 (24.0 %). Of the 65 subjects with an indeterminate pattern, 24 completed a sufficient follow-up (median 25 months; range, 6 - 52), during which some (n=8; 33%) converted to a negative status, some (n=16; 67%) maintained their reactivity pattern, but none became seropositive for HCV. Conclusions. The HCV-RIBA indeterminate status may indicate either a non-specific reaction (false positive) or a real pre-existing or initial infection and does not, therefore, enable a prediction of outcome. The use of HCV genomic assays (nucleic acid amplification testing), which are more specific than antibody-based assays (ELISA, RIBA), therefore improves HCV blood donor testing by allowing an accurate interpretation of such primary assays

Effect of heat treatment on microstructure and erosion resistance of white cast irons for slurry pumping applications

A series of commercial and non-conventional heat treatments was performed to modify the initial as-cast microstructure of two high-chromium (14 wt% and 18 wt% Cr) white cast irons and a low chromium nickel-bearing grade (Ni-Hard 2) for slurry pumping applications. The effect of each heat treatment on the microstructure of the alloys was carefully investigated by optical and scanning electron microscope and X-ray diffraction analysis. Samples were tested for impact erosion resistance in flowing slurry by using a modified-Coriolis apparatus and their weight losses were related to microstructure and hardness. The analysis showed that the erosion resistance of these alloys is related to the carbides volume fraction and hardness, in combination with the matrix microstructure. In case of high-chromium white irons, the destabilization heat treatment (950°C-2h) produced a hard martensitic matrix with secondary carbides that gave superior erosion resistance compared to all other conditions. Excellent performances were obtained also for Ni-Hard 2 in as-cast condition, indicating that this alloy could be an economic alternative to high chromium irons in applications where good erosion resistance is required

Evolving serodiagnostics by rationally designed peptide arrays: the Burkholderia paradigm in Cystic Fibrosis

Efficient diagnosis of emerging and novel bacterial infections is fundamental to guide decisions on therapeutic treatments. Here, we engineered a novel rational strategy to design peptide microarray platforms, which combines structural and genomic analyses to predict the binding interfaces between diverse protein antigens and antibodies against Burkholderia cepacia complex infections present in the sera of Cystic Fibrosis (CF) patients. The predicted binding interfaces on the antigens are synthesized in the form of isolated peptides and chemically optimized for controlled orientation on the surface. Our platform displays multiple Burkholderia-related epitopes and is shown to diagnose infected individuals even in presence of superinfections caused by other prevalent CF pathogens, with limited cost and time requirements. Moreover, our data point out that the specific patterns determined by combined probe responses might provide a characterization of Burkholderia infections even at the subtype level (genomovars). The method is general and immediately applicable to other bacteria