Model of Cortical Cell Processing to Estimate Binocular Disparity

International audienceThe starting point of our work are the physiological and psychophysical studies made on 3D vision, we attempt to build a model of stereoscopic vision. Hence, we used 2D Gabor filters to model the simple and complex cells sensitive to horizontal binocular disparity (Barlow 1967, Daugman 1985). Each of these cells has a preferred disparity and is sensitive to spatial frequency and orientation. It has been shown by Prince et al (2002) that the range of preferred disparities depends on the spatial frequency. We designed a bank of filters in which the distribution of preferred disparity follows the same principle. Moreover, since the stereo-threshold was found to be increasing with the magnitude of disparity inside each spatial frequency channel, the disparity distribution is not uniform. We took the energy model of Ohzawa et al (1986) as a basis since it has been demonstrated that it fits well with the disparity sensitive cells response from V1 in front of most of stimuli. We modified the classical model by normalizing the complex binocular response by the monocular complex response. We took different measures to reduce false matches such as a pooling procedure and an orientation averaging already used by Chen and Qian (2004). As already demonstrated for 2D vision, a coarse-to-fine process seems to be the best way to deal with multiple spatial frequency channels for stereoscopic vision (Smallman 1995, Menz and Freeman 2003). The first estimation based on low spatial frequencies determines if the estimation will be refined channels depending on its inclusion in the disparity range of the higher spatial frequency channel

Using natural versus artificial stimuli to perform calibration for 3D gaze tracking

International audienceThe presented study tests which type of stereoscopic image, natural or artificial, is more adapted to perform efficient and reliable calibration in order to track the gaze of observers in 3D space using classical 2D eye tracker. We measured the horizontal disparities, i.e. the difference between the x coordinates of the two eyes obtained using a 2D eye tracker. This disparity was recorded for each observer and for several target positions he had to fixate. Target positions were equally distributed in the 3D space, some on the screen (with a null disparity), some behind the screen (uncrossed disparity) and others in front of the screen (crossed disparity). We tested different regression models (linear and non linear) to explain either the true disparity or the depth with the measured disparity. Models were tested and compared on their prediction error for new targets at new positions. First of all, we found that we obtained more reliable disparities measures when using natural stereoscopic images rather than artificial. Second, we found that overall a non-linear model was more efficient. Finally, we discuss the fact that our results were observer dependent, with variability's between the observer's behavior when looking at 3D stimuli. Because of this variability, we proposed to compute observer specific model to accurately predict their gaze position when exploring 3D stimuli

Video Outpainting using Conditional Generative Adverarial Networks

Recent advancements in machine learning and neural networks have pushed the boundaries of what computers can achieve. Generative adversarial networks are a specific type of neural network that have proved wildly successful at content generation tasks. With this success, filling in missing sections of images or videos became a research topic of interest. Research in video inpainting has made steady progress throughout the years focusing on filling missing content in the center of a frame while research on video outpainting, which focuses on filling missing sections on the edge of the frame, has not. This thesis focuses on outpainting research by using conditional generative adversarial networks (cGANs) which apply a condition, such as an input image, to a generative adversarial network (GAN) in order to reformat traditional 4:3 video into a modern 16:9 format. This is accomplished by using a cGAN typically used for image-to-image translation and adapting it to generate the missing content from video frames. Although generated frames are not capable of accurately reconstructing missing content, this process is capable of producing context aware video that many times seamlessly blends with the original frame. The results of this research provide a glimpse of the possibility of using conditional generative adversarial networks for video outpainting

La delegación del Poder Tributario en el Poder Ejecutivo, su regulación en el Perú y en otros países andinos

La presente tesis que lleva por título “La delegación del Poder Tributario en el Poder Ejecutivo, su regulación en el Perú y en otros países andinos” trata sobre la delegación legislativa tributaria regulada en los artículos 74 y 104 de la Carta del Perú aprobada en el año 1993, y en los países andinos de Bolivia, Colombia, Ecuador y Venezuela. La doctrina admite que el poder tributario ya no es atribución exclusiva del Poder Legislativo, que originariamente gozaba de esta facultad por estar allí representados los ciudadanos y ser el único que emite leyes, toda vez que el principio de reserva de ley (o legalidad como también se le suele denominar), en el cual se sustentaba dicho poder del Estado, se ha flexibilizado ante la necesidad de “distribuir” el poder tributario en otros entes estatales, para regular los aranceles, en situaciones de emergencia y crisis, y por la necesidad de dotar de facultades legislativas tributarias a entes que gozan de autonomía relativa como los municipios, y delegar atribuciones al Poder Ejecutivo para que legisle sobre temas tributarios. En la presente tesis contrastamos opiniones a favor y en contra sobre la figura en estudio, e identificamos ciertas incongruencias y falencias en el ordenamiento constitucional y tributario peruano que es menester corregir; siendo necesario delimitar el ámbito, los plazos para su ejercicio y las materias sobre las que debe legislar el Poder Ejecutivo, asimismo se reflexiona sobre la necesidad que el Parlamento ejerza un control previo sobre los proyectos de las normas que apruebe el Ejecutivo, cuidando que sean congruentes con las disposiciones y principios tributarios que la Constitución contempla, como garantía de respeto a los derechos de los contribuyentes. Finalmente, exploramos las Constituciones de los países andinos antes citados para conocer si acogen la delegación legislativa tributaria en el Poder Ejecutivo y, de ser el caso, como han desarrollo su tratamiento

Tracking a genetic signal of extinction-recolonization events in a neotropical tree species: Voucapoua americana Aublet in French Guiana

Drier periods from the late Pleistocene and early Holocene have been hypothesized to have caused the disappearance of various rainforest species over large geographical areas in South America and restricted the extant populations to mesic sites. Subsequent improvement in climatic conditions has been associated with recolonization. Changes in population size associated with these extinction‐recolonization events should have affected genetic diversity within species. However, these historical hypotheses and their genetic consequences have rarely been tested in South America. Here, we examine the diversity of the chloroplast and nuclear genomes in a Neotropical rainforest tree species, Vouacapoua americana (Leguminosae, Caesalpinioideae) in French Guiana. The chloroplast diversity was analyzed using a polymerase chain reaction‐restriction fragment length polymorphism method (six pairs of primers) in 29 populations distributed over most of French Guiana, and a subset of 17 populations was also analyzed at nine polymorphic microsatellite loci. To determine whether this species has experienced extinction‐recolonization, we sampled populations in areas supposedly not or only slightly affected by climatic changes, where the populations would not have experienced frequent extinction, and in areas that appear to have been recently recolonized. In the putatively recolonized areas, we found patches of several thousands of hectares homogeneous for chloroplast variation that can be interpreted as the effect of recolonization processes from several geographical origins. In addition, we observed that, for both chloroplast and nuclear genomes, the populations in newly recolonized areas exhibited a significantly smaller allelic richness than others. Controlling for geographic distance, we also detected a significant correlation between chloroplast and nuclear population differentiation. This result indicates a cytonuclear disequilibrium that can be interpreted as a historical signal of a genetic divergence between fragmented populations. In conclusion, the spatial genetic structure of contemporary V. americana populations shows evidence that this species has experienced large extinction‐recolonization events, which were possibly caused by past climatic change

La prueba indiciaria en el delito de tráfico ilícito de drogas y su implicancia en las sentencias condenatorias Ayacucho 2021

El propósito del estudio se centró en analizar de qué manera los jueces penales aplican determinados criterios relativos al ejercicio valorativo de la prueba indiciaria al emitir sus decisiones judiciales contenidas en las sentencias condenatorias respecto a los procesos de tráfico ilícito de drogas en Ayacucho 2021.El enfoque es cualitativo, desarrollado en el contexto de un tipo de investigación aplicada, la que busca la solución de problemas prácticos de la realidad, cuenta con un diseño de investigación fenomenológico, orientado a explorar y comprender el fenómeno a través de las experiencias personales, mediante el empleo de la entrevista efectuadas a los expertos profesionales en la materia abordada, la misma que aportó información de gran relevancia para el propósito de estudio, debiendo precisar que los resultados derivados son confiables y válidos los que permitieron arribar a la conclusión que a través de la aplicación de este mecanismo probatorio puede arribarse a una sentencia condenatoria, arribándose a las conclusiones que los jueces aplican los criterios establecidos en la norma procesal penal y conforme a la jurisprudencia vigente, por otro la valoración adecuada de la prueba por indicios dependerá de la solidez de esta y la correcta valoración realizada por los juzgadores y finalmente, se ha llegado a establecer que la motivación de las decisiones judiciales, dependerá de la justificación en que las sustenten

Dispositivos de protección respiratoria para personal de la salud en el marco de la pandemia por COVID-19

Uno de los peligros ocupacionales en el entorno de la salud es la transmisión aérea de ciertas enfermedades infecciosas. El potencial de exposición no se limita al personal del equipo de salud que atiende directamente a pacientes, sino que abarca también a las personas que entregan comidas, limpian las habitaciones de los pacientes y hacen trabajos de mantenimiento. Todas las personas que trabajan en áreas donde hay pacientes infectados con enfermedades de transmisión aérea están en posible riesgo.Fil: Maggia, Norma. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentina.Fil: Olivera, María Eugenia. Universidad Nacional de Córdoba. Facultad de Ciencias Químicas; Argentina.Fil: Olivera, María Eugenia. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; Argentina.Fil: Maggia, Norma. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Investigación y Desarrollo en Tecnología Farmacéutica; Argentina

La reserva de ley y la aprobación de las alícuotas de los impuestos por norma infralegal

Constituye una investigación doctoral que pone en cuestión la aprobación que efectúa el Poder Ejecutivo de las alícuotas (aspecto mensurable) de los impuestos por norma inferior a una ley o a una con rango de ley, lo cual a nuestro criterio contraviene al longevo principio de reserva de ley en materia tributaria –principio acogido por nuestra norma constitucional en su artículo 74- que informa que la creación de los tributos, en este caso los impuestos, deben ser efectuados por ley o con aquella norma que tenga tal rango y con ello todos sus elementos nucleares que le brindan plena configuración conforme se colige además de lo dispuesto en la Norma IV del Título Preliminar del Texto único Ordenado (en adelante el TUO) del Código Tributario. En la investigación se analiza también si resulta correcta la posición asumida por nuestro Tribunal Constitucional que se ha pronunciado a favor de que en efecto las alícuotas de los impuestos sean aprobados por norma infra legal, siempre que se cuente con una ley autoritativa en la que se establezcan parámetros para tal actuación, lo que creemos podría atenuar la vulneración al principio de reserva de ley, pero que sin embargo no se condice con las disposiciones constitucionales que no autorizan tal acontecer

Environmental and geographical factors structure soil microbial diversity in New Caledonian ultramafic substrates: A metagenomic approach

Soil microorganisms play key roles in ecosystem functioning and are known to be influenced by biotic and abiotic factors, such as plant cover or edaphic parameters. New Caledonia, a biodiversity hotspot located in the southwest Pacific, is one-third covered by ultramafic substrates. These types of soils are notably characterised by low nutrient content and high heavy metal concentrations. Ultramafic outcrops harbour diverse vegetation types and remarkable plant diversity. In this study, we aimed to assess soil bacterial and fungal diversity in New Caledonian ultramafic substrates and to determine whether floristic composition, edaphic parameters and geographical factors affect this microbial diversity. Therefore, four plant formation types at two distinct sites were studied. These formations represent different stages in a potential chronosequence. Soil cores, according to a given sampling procedure, were collected to assess microbial diversity using a metagenomic approach, and to characterise the physico-chemical parameters. A botanical inventory was also performed. Our results indicated that microbial richness, composition and abundance were linked to the plant cover type and the dominant plant species. Furthermore, a large proportion of Ascomycota phylum (fungi), mostly in non-rainforest formations, and Planctomycetes phylum (bacteria) in all formations were observed. Interestingly, such patterns could be indicators of past disturbances that occurred on different time scales. Furthermore, the bacteria and fungi were influenced by diverse edaphic parameters as well as by the interplay between these two soil communities. Another striking finding was the existence of a site effect. Differences in microbial communities between geographical locations may be explained by dispersal limitation in the context of the biogeographical island theory. In conclusion, each plant formation at each site possesses is own microbial community resulting from multiple interactions between abiotic and biotic factors. (Résumé d'auteur