Aprendizaje de circuitos eléctricos en el nivel polimodal : resultados de distintas aproximaciones didácticas

En este trabajo se informa sobre la enseñanza mediante Tutoriales para Física Introductoria de circuitos eléctricos simples en 2º año Polimodal de la escuela pública argentina. La experiencia se realizó en dos escuelas distintas, una estatal mixta y otra privada de mujeres. Se asignó, aleatoriamente, como población de control a otra división de la escuela estatal, donde se continuó con la enseñanza de tipo tradicional. Se utilizó como instrumento de medición un test de respuestas múltiples (DIRECT), que contiene una taxonomía, por demás completa, de concepciones alternativas y dificultades de aprendizaje sobre circuitos eléctricos. Se logró una importante mejora en el aprendizaje conceptual respecto de la enseñanza tradicional, independientemente del nivel socioeconómico, tipo de escuela y género de los alumnos. Se postula que la utilización conjunta de este tipo de estrategia educativa e instrumentos de medición provee condiciones de trabajo adecuadas para una mejora sustancial en la enseñanza de la física en casi cualquier sistema educativo.We report on teaching resistive electric circuits through Tutorials for Introductory Physics to 11th grade students at Argentina high schools. The experiment was carried out at two different schools: one public, state-run, mixed-gender institution and a confessional school only for women. The Determining and Interpreting Resistive Electric Circuits Concepts Tests (DIRECT), which contain a rather complete taxonomy of misconceptions and learning dificulties with regards to electric circuits, were used to measure conceptual learning. Our results show a very significant improvement in conceptual learning when Tutorials are used, as compared to the traditional instruction used in the control population, for students from different socio-economic backgrounds, of different gender and types of schools. We advocate that the complementary use of active learning teaching strategies, like Tutorials, and measuring instruments like DIRECT, provides the conditions for significant improvements in the teaching of physics in almost any educational system

Effects of Interactions with the GroEL Cavity on Protein Folding Rates

AbstractEncapsulation of proteins in chaperonins is an important mechanism by which the cell prevents the accumulation of misfolded species in the cytosol. However, results from theory and simulation for repulsive cavities appear to be inconsistent with recent experimental results showing, if anything, a slowdown in folding rate for encapsulated Rhodanese. We study the folding of Rhodanese in GroEL, using coarse-grained molecular simulations of the complete system including chaperonin and substrate protein. We find that, by approximating the substrate:GroEL interactions as repulsive, we obtain a strong acceleration in rate of between one and two orders of magnitude; a similar result is obtained by representing the chaperonin as a simple spherical cavity. Remarkably, however, we find that using a carefully parameterized, sequence-based potential to capture specific residue-residue interactions between Rhodanese and the GroEL cavity walls induces a very strong reduction of the folding rates. The effect of the interactions is large enough to completely offset the effects of confinement, such that folding in some cases can be even slower than that of the unconfined protein. The origin of the slowdown appears to be stabilization—relative to repulsive confinement—of the unfolded state through binding to the cavity walls, rather than a reduction of the diffusion coefficient along the folding coordinate

Enseñanza de circuitos: ¿dependen los resultados de la experiencia del docente?

El objetivo de este trabajo es mostrar como depende la efectividad de la instrucción de la experiencia del docente. Para ello se comparan los resultados obtenidos por tres docentes de muy distinta experiencia, un profesor con más de 20 años de experiencia docente y dos alumnos de Profesorado en Física, que realizaron esta instrucción como parte de sus prácticas docentes. La estrategia utilizada en las tres clases experimentales fue Tutoriales para Física Introductoria, que fue implementada en similares condiciones en distintas clases de la escuela secundaria. En todos los casos el conocimiento conceptual fue determinada con el test DIRECT. Trabajos previos de nuestro grupo había mostrado que Tutoriales produce un aprendizaje conceptual más profundo y duradero que la instrucción tradicional, independientemente del género y condición socio-económica de los estudiantes. El presente trabajo muestra que los buenos resultados se mantienen independientemente de la experiencia del docente, siempre que el mismo haya tenido un adecuado entrenamiento en la utilización de metodologías de enseñanza para el aprendizaje activo.The aim of this work is to show how the efficiency of instruction depends on teacher's experience. The conceptual knowledge on electric circuits have been measured with the test DIRECT on four classes taught by three teachers of very different experience: one with more than 20 years of teaching experience, and other two that taught this subject as part of their pre-graduation training. Tutorials for Introductory Physics was the activelearning teaching strategy used in all cases, implemented under similar conditions. The present results indicate that the efficiency of instruction was the same for all teachers, provided they use the same teaching strategy and have been properly trained for it. It also confirmed, for these inexperienced teachers, that Tutorials is clearly more efficient than traditional instruction in fostering conceptual learning.Fil: Sirur Flores, J.. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; ArgentinaFil: Lenhe, G.. Colegio San Luis Gonzaga; ArgentinaFil: Sánchez, E.. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; ArgentinaFil: Benegas, Julio Ciro. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - San Luis. Instituto de Matemática Aplicada de San Luis "Prof. Ezio Marchi". Universidad Nacional de San Luis. Facultad de Ciencias Físico, Matemáticas y Naturales. Instituto de Matemática Aplicada de San Luis ; Argentina. Universidad Nacional de San Luis. Facultad de Ciencias Físico Matemáticas y Naturales. Departamento de Física; Argentin

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Obras sobre inmueble propio. Tratamiento impositivo

Trabajo final de posgrado (Especialización en Tributación)Como uno de los componentes fundamentales del desarrollo y crecimiento económico de un país, está la actividad de la construcción; la cual se encuadra dentro de un tratamiento tributario muy complejo. El sujeto empresa constructora debe tener muy claro tanto la forma jurídica que adopte, como así también el tipo de operaciones que realice, principalmente cuando se trata de obra sobre inmueble propio. Se puede vislumbrar que se está ante un caso particular de Hecho Imponible complejo, ya que, en el Impuesto al Valor Agregado, si bien la obra sobre inmueble propio se cataloga como un servicio, el nacimiento del hecho imponible se da con la venta. A su vez, la base de imposición no es el precio de venta sino la parte del mismo correspondiente a la obra. En la práctica existen diversas situaciones en las cuales el tratamiento impositivo da a lugar al nacimiento de diferentes posturas doctrinarias (intereses, señas, alícuotas, etc.). Las leyes impositivas argentinas difieren en el tratamiento de acuerdo a la forma jurídica que adopte el sujeto empresa constructora (Fideicomiso, Consorcios, Cooperativas, Persona física, etc.) como así también de acuerdo al tipo de operatorias que realice, estableciendo exenciones, alícuotas diferenciales, y tratamientos particulares a situaciones especiales. Es importante destacar, que si bien este trabajo desarrolla separadamente los distintos aspectos contemplados en las leyes tributarias (objeto, hecho imponible, sujeto, base imponible) para definir o no la gravabilidad de una obra, deben tenerse en cuenta todas las normas que regulan estos aspectos, aplicándolas de manera combinada.Fil: Sirur Flores, Mariela Lilián. Universidad Nacional de Córdoba. Facultad de Ciencias Económicas; Argentina

Simulating the Impact of Personality on Fake News

Fake news is a key issue for social networks. We use an agent-based network simulation to model the spread of (fake) news. The agents' behaviour captures the OCEAN ("big five") personality trait model. The network is homophilic for political preference, analytical thinking and emotion. We studied the system with personality traits and homophily each turned on/off. Personality traits and homophily exhibited a statistically significant but typically minimal impact. Ignoring personality traits when modelling fact-checking can overestimate its effectiveness

A clinical study of arrhythmias associated with acute myocardial infarction and thrombolysis

Background: Arrhythmias are a common occurrence in ACS. This study was undertaken to analyze the incidence, frequency and type of arrhythmias in relation to the site of infarction to aid in timely intervention to modify the outcome in MI and to study the significance of Reperfusion arrhythmias.Methods: 100 patients were evaluated. ECG and cardiac enzymes were studied. Arrhythmias complicating AMI in terms of their incidence, timing, severity, type, relation, reperfusion and results were studied.Results: Of the 100 cases, 74% were males and 26% females of which incidence being common between 4th to 7th decades of life. AMI was common in patients with Diabetes and Hypertension (23% each). Incidence of AWMI (58%) is higher than IWMI (40%). Out of all arrhythmias, Ventricular Tachycardia was seen in 24% cases with 50% mortality and preponderance to Antero Lateral Myocardial Infarction. Sinus Tachycardia was seen in 23% of cases with preponderance to Antero Lateral Myocardial Infarction and persistence of Sinus Tachycardia was a prognostic sign, mortality being 22%. Complete Heart Block and Sinus Bradycardia were seen with IWMI, incidence being 53.8% and 100% respectively. Bundle Branch Block was common in AWMI (31%) than IWMI (10%). Among 64 thrombo-lysed cases, 21 had Reperfusion Arrhythmias without any mortality, whereas remaining 43 without Reperfusion Arrhythmias had mortality of 18.6%.Conclusions: According to the study, Tachy-arrhythmias are common with Anterior Wall Myocardial Infarction and Brady-arrhythmias in Inferior Wall Myocardial Infarction. Reperfusion Arrhythmias are a benign phenomenon and good indicator of successful reperfusion

A weak characterization of slow variables in stochastic dynamical systems

We present a novel characterization of slow variables for continuous Markov processes that provably preserve the slow timescales. These slow variables are known as reaction coordinates in molecular dynamical applications, where they play a key role in system analysis and coarse graining. The defining characteristics of these slow variables is that they parametrize a so-called transition manifold, a low-dimensional manifold in a certain density function space that emerges with progressive equilibration of the system's fast variables. The existence of said manifold was previously predicted for certain classes of metastable and slow-fast systems. However, in the original work, the existence of the manifold hinges on the pointwise convergence of the system's transition density functions towards it. We show in this work that a convergence in average with respect to the system's stationary measure is sufficient to yield reaction coordinates with the same key qualities. This allows one to accurately predict the timescale preservation in systems where the old theory is not applicable or would give overly pessimistic results. Moreover, the new characterization is still constructive, in that it allows for the algorithmic identification of a good slow variable. The improved characterization, the error prediction and the variable construction are demonstrated by a small metastable system