1,752 research outputs found

    On the reduction of 4-oxo-4h-benzopyran-3-carbaldehydes : global and local electrophilicity patterns

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    The theoretical global and local electrophilicity patterns of substituted and chelated 4-oxo-4H-benzopyran-3-carbaldehydes (formylchromones) have been evaluated using the electrophilicity index proposed by Parr et al [J. Am. Chem. Soc. 1999, 121, 1922]. The complexation of formylchromones with aluminum predicts a strong electrophilic character of these compounds against nucleophiles. Local response at the active sites may also be assessed in terms of a global contribution described by the global electrophilicity, and a local contribution described by the variations in electrophilic Fukui function at those sites. The highest local electrophilicity is found at the formyl group of the chelated formylchromones, in spite of that, the highest positive charge is located on the pyrone carbonyl group. This result is consistent with the experimental observed reactivity displayed by 4-oxo-4H-benzopyran-3-carbaldehydes in the presence of 2-propanol and alumina

    Extreme compass and Dynamic Multi-Armed Bandits for Adaptive Operator Selection

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    The goal of adaptive operator selection is the on-line control of the choice of variation operators within evolutionary algorithms. The control process is based on two main components, the credit assignment, that defines the reward that will be used to evaluate the quality of an operator after it has been applied, and the operator selection mechanism, that selects one operator based on some operators qualities. Two previously developed adaptive operator selection methods are combined here: Compass evaluates the performance of operators by considering not only the fitness improvements from parent to offspring, but also the way they modify the diversity of the population, and their execution time; dynamic multi-armed bandit proposes a selection strategy based on the well-known UCB algorithm, achieving a compromise between exploitation and exploration, while nevertheless quickly adapting to changes. Tests with the proposed method, called ExCoDyMAB, are carried out using several hard instances of the satisfiability problem (SAT). Results show the good synergetic effect of combining both approaches

    EEG characterization of the Alzheimer's disease continuum by means of multiscale entropies

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    Alzheimer's disease (AD) is a neurodegenerative disorder with high prevalence, known for its highly disabling symptoms. The aim of this study was to characterize the alterations in the irregularity and the complexity of the brain activity along the AD continuum. Both irregularity and complexity can be studied applying entropy-based measures throughout multiple temporal scales. In this regard, multiscale sample entropy (MSE) and refined multiscale spectral entropy (rMSSE) were calculated from electroencephalographic (EEG) data. Five minutes of resting-state EEG activity were recorded from 51 healthy controls, 51 mild cognitive impaired (MCI) subjects, 51 mild AD patients (ADMIL), 50 moderate AD patients (ADMOD), and 50 severe AD patients (ADSEV). Our results show statistically significant differences (p-values < 0.05, FDR-corrected Kruskal-Wallis test) between the five groups at each temporal scale. Additionally, average slope values and areas under MSE and rMSSE curves revealed significant changes in complexity mainly for controls vs. MCI, MCI vs. ADMIL and ADMOD vs. ADSEV comparisons (p-values < 0.05, FDR-corrected Mann-Whitney U-test). These findings indicate that MSE and rMSSE reflect the neuronal disturbances associated with the development of dementia, and may contribute to the development of new tools to track the AD progression.This research was supported by European Commission and European Regional Development Fund (FEDER) under project “Análisis y correlación entre el genoma completo y la actividad cerebral para la ayuda en el diagnóstico de la enfermedad de Alzheimer” (Cooperation Programme Interreg V-A Spain-Portugal, POCTEP 2014-2020); by “Ministerio de Ciencia, Innovación y Universidades” and FEDER under projects PGC2018-098214-A-I00 and DPI2017-84280-R; and by “Fundação para a Ciência e a Tecnologia/Ministério da Ciência, Tecnologia e Inovação” and FEDER under projects POCI-01-0145-FEDER-007274 and UID/MAT/00144/2013

    Cognition as Embodied Morphological Computation

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    Cognitive science is considered to be the study of mind (consciousness and thought) and intelligence in humans. Under such definition variety of unsolved/unsolvable problems appear. This article argues for a broad understanding of cognition based on empirical results from i.a. natural sciences, self-organization, artificial intelligence and artificial life, network science and neuroscience, that apart from the high level mental activities in humans, includes sub-symbolic and sub-conscious processes, such as emotions, recognizes cognition in other living beings as well as extended and distributed/social cognition. The new idea of cognition as complex multiscale phenomenon evolved in living organisms based on bodily structures that process information, linking cognitivists and EEEE (embodied, embedded, enactive, extended) cognition approaches with the idea of morphological computation (info-computational self-organisation) in cognizing agents, emerging in evolution through interactions of a (living/cognizing) agent with the environment

    Supraorganized Collagen Enhances Schwann Cell Reactivity And Organization In Vitro.

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    We investigated the reactivity and expression of basal lamina collagen by Schwann cells (SCs) cultivated on a supraorganized bovine-derived collagen substrate. SC cultures were obtained from sciatic nerves of neonatal Sprague-Dawley rats and seeded on 24-well culture plates containing collagen substrate. The homogeneity of the cultures was evaluated with an SC marker antibody (anti-S-100). After 1 week, the cultures were fixed and processed for immunocytochemistry by using antibodies against type IV collagen, S-100 and p75NTR (pan neurotrophin receptor) and for scanning electron microscopy (SEM). Positive labeling with antibodies to the cited molecules was observed, indicating that the collagen substrate stimulates SC alignment and adhesion (collagen IV labeling - organized collagen substrate: 706.33 ± 370.86, non-organized collagen substrate: 744.00 ± 262.09; S-100 labeling - organized collagen: 3809.00 ± 120.28, non-organized collagen: 3026.00 ± 144.63, P < 0.05) and reactivity (p75NTR labeling - organized collagen: 2156.33 ± 561.78, non-organized collagen: 1424.00 ± 405.90, P < 0.05; means ± standard error of the mean in absorbance units). Cell alignment and adhesion to the substrate were confirmed by SEM analysis. The present results indicate that the collagen substrate with an aligned suprastructure, as seen by polarized light microscopy, provides an adequate scaffold for SCs, which in turn may increase the efficiency of the nerve regenerative process after in vivo repair.44682-

    El delito de herejía:"iter" jurídico

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    Towards Autopoietic Computing

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    A key challenge in modern computing is to develop systems that address complex, dynamic problems in a scalable and efficient way, because the increasing complexity of software makes designing and maintaining efficient and flexible systems increasingly difficult. Biological systems are thought to possess robust, scalable processing paradigms that can automatically manage complex, dynamic problem spaces, possessing several properties that may be useful in computer systems. The biological properties of self-organisation, self-replication, self-management, and scalability are addressed in an interesting way by autopoiesis, a descriptive theory of the cell founded on the concept of a system's circular organisation to define its boundary with its environment. In this paper, therefore, we review the main concepts of autopoiesis and then discuss how they could be related to fundamental concepts and theories of computation. The paper is conceptual in nature and the emphasis is on the review of other people's work in this area as part of a longer-term strategy to develop a formal theory of autopoietic computing.Comment: 10 Pages, 3 figure

    La indagación científica como enfoque pedagógico: estudio sobre las prácticas innovadoras de docentes de ciencia en EM (Región de Valparaíso)

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    RESUMEN: El presente trabajo refiere los resultados de un estudio cualitativo cuyo objetivo fue describir y comprender las prácticas de seis docentes de ciencia en Educación Secundaria que han logrado transformar su enseñanza, aproximándose a un enfoque indagatorio. El enfoque metodológico empleado fue Grounded Theory, el cual se aplicó a la observación de 54 horas (cr.) de clase. El estudio aporta con información descriptiva y comprensiva sobre las características de las prácticas observadas, así como las condiciones que las permiten y las consecuencias que conllevan. Se finaliza discutiendo el impacto que este estudio tiene sobre la formación inicial y continua de docentes de ciencia de Educación Secundaria. ABSTRACT: This research refers the results of a qualitative study which purpose was to describe and understand the teaching practices of six secondary science teachers who have transformed their teaching practice by applying an inquiry approach. The method used was Grounded Theory applied to the observation of 54 class hours (cr.). This research contributes with descriptive and comprehensive information about characteristics of the observed practices, as well as the conditions that allow them and their consequences. Finally, we discuss the implications that this study has on pre-service and in-service secondary science teacher education

    Profesionalismo y auto cuidado de los residentes, ¿cómo debemos enfocar su formación?

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    El profesionalismo es una competencia bien definida en la educación de los residentes, sin embargo, es un constructo complejo, sensible a variables sociales y culturales. Puede definirse como el nivel de destreza, buen juicio y comportamiento adecuado esperable de personas entrenadas para realizar bien su trabajo. Es una competencia que no se mantiene estable en el tiempo y decae cuando el profesional está sometido a altos niveles de estrés y se asocia a calidad de cuidado, educación, ética, moral, filosofía y humanismo. Es una competencia esencial en el profesional por lo cual debemos replantear los currículos para incluir formas de enseñar y evaluar el profesionalismo. Es fundamental pensar en programas que logren equilibrar la carga de trabajo con el bienestar de los futuros profesionales. Debemos generar un clima adecuado de aprendizaje donde el profesional en entrenamiento sea un protagonista activo, y el auto cuidado sea visibilizado como una competencia esencial para mantener el equilibrio entre la vida personal y profesional. Este articulo plantea una revisión y reflexión de este tema que cobra cada vez mas importancia en la formación de postgrado de futuros especialistas
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