3,300 research outputs found

    aspBEEF: Explaining Predictions Through Optimal Clustering

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    [Abstract] In this paper we introduce aspBEEF, a tool for generating explanations for the outcome of an arbitrary machine learning classifier. This is done using Grover’s et al. framework known as Balanced English Explanations of Forecasts (BEEF) that generates explanations in terms of in terms of finite intervals over the values of the input features. Since the problem of obtaining an optimal BEEF explanation has been proved to be NP-complete, BEEF existing implementation computes an approximation. In this work we use instead an encoding into the Answer Set Programming paradigm, specialized in solving NP problems, to guarantee that the computed solutions are optimal.Ministerio de Asuntos Económicos y Transformación Digital; TIN2017-84453-PXunta de Galicia; GPC ED431B 2019/03Xunta de Galicia; ED431G 2019/0

    La historia y los historiadores en el siglo XXI

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    The mission of this text is to explain why History has ceased to have in the last three decades the public presence and persuasive power that it had during the 19th century and the first half of the 20th century. We propose that History should articulate plural stories in order to generate a better intercultural connection in the global world in which we live and to overcome exclusive nationalist stories.Este texto tiene como misión explicar por qué la Historia ha ido dejando de tener en las tres últimas décadas la presencia pública y el poder persuasivo que tuvo durante el siglo XIX y buena parte del siglo XX. Se propone en las conclusiones que la Historia debe mostrar relatos plurales que ayuden a generar una mejor conexión intercultural en el mundo global en el que vivimos y a superar los relatos nacionalistas excluyentes.&nbsp

    Romera y Romero (Brest). La construcción de un espacio de comunicación artística entre Chile y Argentina (1942-1964)

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    The elaboration of this essay is part of a research project conceived around the documentary archive of the Spanish-Chilean art critic Antonio Romera (1908-1975). Among the numerous letters that make up this archive, we have located a total of fourteen letters addressed, between 1943 and 1964, by the Argentine art critic Jorge Romero Brest (1905-1989) to Romera, which, although intermittently, allow us to trace an overview of the links that they maintained at least in those more than twenty years. Going through the content of these letters, we extracted those themes that appeared as central and reiterated in them, defining the very headings of this article; They are: a) comments related to another of Antonio Romera’s priority activities, his work as a cartoonist; b) Romera’s contribution (and non-contribution) to the magazine founded and directed by Romero Brest (with the collaboration of his disciples), Ver y Estimar (1948-1955); c) the mutual comments and reviews between Romera and Romero Brest on the books they published between the 1940s and 1950s.La elaboración de este ensayo se enmarca dentro de un proyecto de investigación concebido en torno al archivo documental del crítico de arte hispano-chileno Antonio Romera (1908-1975). Entre las numerosas cartas de que consta dicho acervo, hemos localizado un total de catorce cartas dirigidas, entre 1943 y 1964, por el crítico de arte argentino Jorge Romero Brest (1905-1989) a Romera, que, aunque de manera intermitente, permiten trazar un panorama de los vínculos que mantuvieron al menos en esos más de veinte años. Atravesando el contenido de dichas misivas, extrajimos aquellos temas que aparecían como centrales y reiterados en las mismas, definiendo los propios epígrafes de este artículo; ellos son: a) comentarios vinculados con otra de las actividades prioritarias de Antonio Romera, su tarea como caricaturista; b) la contribución (y no contribución) de Romera a la revista fundada y dirigida por Romero Brest (con la colaboración de sus discípulos), Ver y Estimar (1948-1955); c) los comentarios y reseñas mutuos entre Romera y Romero Brest al hilo de los libros que fueron publicando entre los años 40 y 50

    A dilated pore of winer in a young Iberian lynx (Lynx Pardinus)

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    A 1.5-year-old male Iberian lynx born in captivity presented with a 2.2 cm exophytic nodular alopecic mass at the left tarsus medial aspect, before being released into the wild. The lesion had keratinised material protruding through a 1.2 cm pore, forming a cutaneous horn. Histopathology revealed a cystic dermo-epidermal lesion lined by psoriasiform hyperplasia of the epithelium, thicker at the base of the cyst, together with abrupt to progressive keratinization and keratin pearls. The central cystic cavity was filled with fibrillary keratin and ghost cells. Immunohistochemistry for pan-cytokeratin showed strong positive immunolabeling in the hyperplastic epithelium and a weaker immunolabeling at the content of the cyst. A final diagnosis of a Dilated Pore of Winer was made. This paper is the first reported case of a DPW in a lynx and a wild felid

    Percepción del clima motivacional de la clase de educación física, en estudiantes de enseñanza media perteneciente a una comuna de la provincia de Ñuble, región del Bío-Bío, Chile

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    El presente artículo entrega los resultados obtenidos del estudio sobre Percepción del Clima Motivacional de las Clases de Educación Física, en estudiantes de enseñanza media, pertenecientes a una comuna de provincia de Ñuble, región del Bío-Bío, Chile. Para ello se definió una muestra de tipo estratificada para seleccionar dos grupo cursos pertenecientes a establecimientos de una de las comunas de la provincia de Ñuble, a los que se aplicó la versión española del instrumento PMCSQ-2, (Balaguer, Guivernau y Duda 1997; Sánchez- Oliva, Leo, Sánchez, Alonso y García-Calvo 2010; Cervelló y Santos-Rosa 2000; Cervelló, Moreno, Del Villar y Reina 2007, diseñado y validado en inglés por Newton y Duda 1993 y Newton, Duda, y Yin.2000). Los principales resultados dan cuenta, en general, que los sujetos bajo estudio expresan mayoritariamente un agrado por la clase de Educación Física, donde se infiere que los estudiantes perciben que la práctica de enseñanza del profesor estimula el aprendizaje colaborativo y valora el esfuerzo realizado por ellos, por sobre prácticas centradas en el “castigo” o reprimenda por sus errores y refuerzo de valores de competitividad. Sin embargo, y a diferencia de los estudios citados en la investigación, no se encontraron diferencias significativas por género de dicha percepción.The article presents results from a research study about Perception of the Motivational environment with in Physical Education highschool students belonging to Provincia de Ñuble, Bío-Bío Region, Chile. Thestudy examines the importance of building favorable habits and attitudes towards physical activities as stated in current debates related to quality of education, focusing the discussion on students’ perception about Phys Ed and its relation with present and future sport habits. To carry out this study, we defined a stratified sample composed of two high school groups, who were applied the Spanish version of PMCSQ-2 instrument (Balaguer, Guivernau y Duda 1997; Sánchez-Oliva, Leo, Sánchez, Alonso y García-Calvo2010; Cervelló y Santos- Rosa 2000; Cervelló, Moreno, Del Villar y Reina 2007, originally designed and validated in English by Newton y Duda, 1993 y Newton, Duda, Yin 2000). The main findings show that, in general, the student subjects greatly expressed their satisfaction for Phys Ed sessions. We can infer that they perceived teaching practice as something that both stimulates collaborative learning and values their efforts, rather than as a ‘punishment’ or reprimand for their errors, or reinforcement of competitive values. Notwithstanding, we did not find significant related gender differences.Dossier II: Infancia y Educación

    Surface tension and microgravity

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    The behaviour of confined liquids on board an orbiting spacecraft is mainly driven by surface tension phenomena, which cause an apparently anomalous response of the liquid when compared with the behaviour that can be observed on an Earth laboratory provided that the amount of liquid is high enough. The reason is that in an orbiting spacecraft the different inertial forces acting on the bulk of the liquid are almost zero, causing thus capillary forces to be the dominant ones. Of course, since gravity forces are proportional to the liquid volume, whereas surface tension forces are proportional to the liquid surface, there are situations on Earth where capillarity can be the dominant effect, as it happens when very small volume liquid samples are considered. However, work with small size samples may require the use of sophisticated optical devices. Leaving aside the neutral buoyancy technique, a way of handling large liquid interfaces is by using drop towers, where the sample falls subjected to the action of Earth's gravity. This approach is suitable when the characteristic time of the problem under consideration is much smaller than the drop time. In this work the transformation of an out-of-use chimney into a drop tower is presented. Because of the miniaturization, hardiness and low cost of current electronic devices, a drop tower can be used as an inexpensive tool for undergraduate students to experimentally analyse a large variety of surface tension driven phenomena

    Diagnóstico incidental en tiempos de coronavirus: mixoma cardíaco en orejuela izquierda

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    Cardiac myxoma is the most common primary intracardiac benign tumour. Left atrium is the most frequent location,right next to the interatrium septum. Echocardiography is the technique of choice for detecting myxoma. We present a case which peculiarity is the atypical location of the mass in the left appendage and the diagnosis as an incidental finding in a CT scan as part of the “Management of patients under suspicion of COVID-19” protocolEl mixoma cardiaco es el tumor primario benigno intracardiaco más frecuente. Su localización típica la encontramos en la aurícula izquierda, adherido al septo interauricular. La ecocardiografía es su principal método diagnóstico. Se presenta el caso de un mixoma cardiaco que como peculiaridades tiene en primer lugar una localización atípica al situarse en orejuela izquierda y en segundo lugar, que se diagnostica a partir del hallazgo accidental de una masa auricular en una TAC solicitado en nuestro servicio de Urgencias como aplicación directa del protocolo sobre “Manejo de los pacientes bajo sospecha de COVID-19”

    Procedimiento para el cálculo de la distribución óptima de seguidores en un campo fotovoltaico de alta concentración

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    Los sistemas fotovoltaicos de alta concentración producen electricidad utilizando dispositivos ópticos que concentran la luz solar sobre celdas fotovoltaicas de pequeño tamaño. Este tipo de sistemas están compuestos por seguidores solares a dos ejes en los cuales, diariamente, se producen condiciones de auto sombreado. En este artículo se presenta un procedimiento para determinar la separación óptima de seguidores en una planta fotovoltaica de alta concentración, balanceando las pérdidas de energía por sombreado con las pérdidas de energía en los cables y con el costo del terreno. El procedimiento se aplica como ejemplo a un sistema hipotético a ubicar en Celaya, México

    Three-dimensional spatial distribution of synapses in the neocortex: A dual-beam electron microscopy study

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    In the cerebral cortex, most synapses are found in the neuropil, but relatively little is known about their 3-dimensional organization. Using an automated dual-beam electron microscope that combines focused ion beam milling and scanning electron microscopy, we have been able to obtain 10 three-dimensional samples with an average volume of 180 µm(3) from the neuropil of layer III of the young rat somatosensory cortex (hindlimb representation). We have used specific software tools to fully reconstruct 1695 synaptic junctions present in these samples and to accurately quantify the number of synapses per unit volume. These tools also allowed us to determine synapse position and to analyze their spatial distribution using spatial statistical methods. Our results indicate that the distribution of synaptic junctions in the neuropil is nearly random, only constrained by the fact that synapses cannot overlap in space. A theoretical model based on random sequential absorption, which closely reproduces the actual distribution of synapses, is also presented
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