What's wrong with classes? The theory of Knowledge

This paper wants to investigate the deepest meaning of the word class that is often used in machine learning and classification as a well-defined concept. This adventure will lead the reader to the fundamentals of Mathematics like set theory from Zermelo-Fraenkel. This will be our start, like is all Mathematics, to understand how well defined is the class concept. A broader theory will be outlined with the courageous attempt to give an homogenous framework to deal with machine learning problems

Role of Dps (DNA-binding proteins from starved cells) aggregation on DNA.

The review outlines the experimental studies that have led to the current understanding at a molecular level of the protective role exerted by Dps proteins under stress conditions. After a brief description of the structural signatures and of the ferroxidase activity, which confers to all Dps proteins the capacity to decrease the hydroxyl radical induced DNA damage, the interaction of some family members with DNA is analysed. Special emphasis is given to the Dps structural elements that render the interaction with DNA possible and to the consequences that complex formation has on nucleoid organization and microbial survival

ESTUDIOS DE DOCTORADO, GESTIÓN UNIVERSITARIA Y GARANTÍA DE LA CALIDAD DE LA EDUCACIÓN SUPERIOR EN LOS NUEVOS ESPACIOS REGIONALES

Los estudios doctorales, constituyen el resultado natural de la consolidación de la oferta de posgraduación de las instituciones de educación superior y constituyen un capítulo esencial de su contribución a la investigación, a la generación de conocimiento nuevo y a la inserción de las sociedades nacionales en la sociedad del conocimiento. Su desarrollo y gestión, las características que eventualmente poseen no son, en consecuencia, irrelevantes en términos de poder, estrategias y gestión de las universidades. El objetivo de este trabajo es el de revisar, aun en forma provisional, esa cuestión clave para el desarrollo convergente de lo que podríamos denominar una Educación Superior sudamericana y hacerlo a partir de los específicos desarrollos latinoamericanos y de los recientes aportes que se procesan en Europa y en los Estados Unidos, en el entendido de que la cooperación académica y la internacionalización, constituyen aspectos centrales de la emergente sociedad del conocimiento, llamada a transformar talvez como nunca antes, la vida de las universidades

Scale Object Selection (SOS) through a hierarchical segmentation by a multi-spectral per-pixel classification

International audienceIn high resolution multispectral optical data, the spatial detail of the images are generally smaller than the dimensions of objects, and often the spectral signature of pixels is not directly representative of classes we are interested in. Thus, taking into account the relations between groups of pixels becomes increasingly important, making object­oriented approaches preferable. In this work several scales of detail within an image are considered through a hierarchical segmentation approach, while the spectral information content of each pixel is accounted for by a per­pixel classification. The selection of the most suitable spatial scale for each class is obtained by merging the hierarchical segmentation and the per­pixel classification through the Scale Object Selection (SOS) algorithm. The SOS algorithm starts processing data from the highest level of the hierarchical segmentation, which has the least amount of spatial detail, down to the last segmentation map. At each segmentation level, objects are assigned to a specific class whenever the percentage of pixels belonging to the latter, according to a pixel­based procedure, exceeds a predefined threshold, thereby automatically selecting the most appropriate spatial scale for the classification of each object. We apply our method to multispectral, panchromatic and pan­sharpened QuickBird images

Estudios de doctorado y gestión universitaria: tendencias globales y experiencias locales

El presente trabajo se propone una indagación sobre los retos planteados por los estudios de doctorado a la gestión universitaria, estudios doctorales cuya revisión ha tenido lugar en años recientes, en diversas regiones del mundo. Para ello explora las tendencias globales que se evidencian en esa revisión (incremento en el número de programas, redefiniciones conceptuales y nuevas funciones, diversificación de los tipos de programas, componentes centrales y experiencias de educación, evaluación y auditoría, entre otras), caracterizando a la formación doctoral en términos de sus procesos y productos. La cuestión de los estudios de nivel doctoral es analizada en referencia a los nuevos imperativos de gestión del conocimiento, emergentes de las tendencias de transformación del campo de la educación superior y a la práctica de las instituciones. Con ese propósito se revisa la situación del Uruguay, caracterizada por su tardía institucionalización de un sistema de posgrados en ciencias básicas y en tecnologías, aun en curso tanto en lo relativo a otras áreas del conocimiento, como en referencia a su evaluación y acreditación. . Los casos de las ciencias sociales y del área biomédica, son revisados finalmente, a efectos de dar cuenta de aspectos de la práctica local, y de los procesos específicos de un entorno científico periférico

Ligand binding to the dimeric hemoglobin from Scapharca inaequivalvis, a hemoglobin with a novel mechanism for cooperativity.

Abstract The homodimeric hemoglobin from Scapharca inaequivalvis has an unusual spatial arrangement of the subunits (Royer, W.E., Jr., Love, W.E., and Fenderson, F.F. (1985) Nature 316, 277-280). The time course of oxygen and nitric oxide rebinding to this protein following flash photolysis has been measured on a nanosecond time scale. A large amplitude is observed with a half-time of 20 ns (NO). With oxygen the half-time decreases from 70 ns at low fractional photolysis to 30 ns at large breakdown. The second order rate of NO binding is 1.6 x 10(7)/MS, and is the same as that for oxygen. Analysis of the geminate data suggests that oxygen and nitric oxide react more rapidly with the heme than in myoglobin, but also escape much more rapidly from its vicinity

Student Sliced Inverse Regression

International audienceSliced Inverse Regression (SIR) has been extensively used to reduce the dimension of the predictor space before performing regression. SIR is originally a model free method but it has been shown to actually correspond to the maximum likelihood of an inverse regression model with Gaussian errors. This intrinsic Gaussianity of standard SIR may explain its high sensitivity to outliers as observed in a number of studies. To improve robustness, the inverse regression formulation of SIR is therefore extended to non-Gaussian errors with heavy-tailed distributions. Considering Student distributed errors it is shown that the inverse regression remains tractable via an Expectation- Maximization (EM) algorithm. The algorithm is outlined and tested in the presence of outliers, both in simulated and real data, showing improved results in comparison to a number of other existing approaches

Collaborative Sliced Inverse Regression

International audienceSliced Inverse Regression (SIR) is an effective method for dimensionality reduction in high-dimensional regression problems. However, the method has requirements on the distribution of the predictors that are hard to check since they depend on unobserved variables. It has been shown that, if the distribution of the predictors is elliptical, then these requirements are satisfied.In case of mixture models, the ellipticity is violated and in addition there is no assurance of a single underlying regression model among the different components. Our approach clusterizes the predictors space to force the condition to hold on each cluster and includes a merging technique to look for different underlying models in the data. A study on simulated data as well as two real applications are provided. It appears that SIR, unsurprisingly, is not capable of dealing with a mixture of Gaussians involving different underlying models whereas our approach is able to correctly investigate the mixture

Studies on the Relations between Molecular and Functional Properties of Hemoglobin: VII. KINETIC EFFECTS OF THE REVERSIBLE DISSOCIATION OF HEMOGLOBIN INTO SINGLE CHAIN MOLECULES

Abstract The kinetics of the reactions of human hemoglobin with carbon monoxide and oxygen has been studied in photochemical and rapid mixing experiments over a large range of hemoglobin concentration. When the reaction is initiated by rapid removal of the ligand from ligand-bound hemoglobin, the kinetics of the combination of hemoglobin with CO shows a marked concentration dependence in both the photochemical and the rapid mixing experiments. In dilute hemoglobin solutions (below 10-5 m in heme), dissociation of the ligand from oxyhemoglobin or carbonmonoxyhemoglobin is followed by slow changes (half-time of the order of seconds) in the properties of the system. These results lead to the following picture, which is also consistent with other as yet unexplained aspects of hemoglobin kinetics. (a) Ligand-bound hemoglobin dissociates reversibly into single chain molecules at concentrations below 10-5 m. (b) Deoxygenated hemoglobin has a much lower tendency to dissociate into single chain molecules, and there is no appreciable dissociation even at concentrations of the order of 10-6 to 10-7 m. (c) The association of deoxygenated α and β chains is a relatively slow process. Therefore, after sudden dissociation of the ligand from dilute hemoglobin solutions, the properties of the system, for a brief time, are those of a mixture of deoxygenated hemoglobin and deoxygenated α and β chains. (d) The properties of the single chain molecules obtained by dilution of ligand-bound hemoglobin are the same as those of isolated α and β hemoglobin chains as obtained by preparative procedures

NUEVOS TERRITORIOS Y FRONTERAS DEL CONOCIMIENTO: DESAFÍOS DE LA FORMACIÓN AVANZADA EN AMÉRICA LATINA

Este artículo es un avance de una investigación en curso, en el marco de una línea de trabajo más amplia sobre las nuevas tendencias contemporáneas en los estudios doctorales. Esta investigación, parte de las siguientes cuestiones: ¿Cuáles son los desafíos que los nuevos campos científico tecnológicos imponen a la formación avanzada? y ¿De qué manera esos desafíos han sido abordados en los doctorados en nuestra región con diversos recursos y tradiciones científicas? La metodología parte del análisis cualitativo (entrevistas, revisión documental, de una muestra de programas de doctorado en el campo de la nanociencia y de la nanotecnología, de reciente desarrollo y creciente importancia económica. Estos enfrentan múltiples tensiones entre las nuevas formas de producción de conocimiento, las relaciones entre los practicantes de las diversas disciplinas, subdisciplinas y otras divisiones de los campos científicos, así como las demandas de diversos agentes externos e internos de los sistemas educativos. El trabajo concluye que para las instituciones de educación superior, los desafíos de los doctorados se configuran en torno a i) las propias dinámicas de la producción y difusión del conocimiento, y ii) la viabilidad y sustentabilidad de los programas de formación avanzada