2,599 research outputs found

    Motivic Milnor fiber of a quasi-ordinary hypersurface

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    Let f : (Cd+1, 0) -> (C, 0) be a germ of complex analytic function such that its zero level defines an irreducible germ of quasi-ordinary hypersurface (S, 0) subset of (Cd+1, 0). We describe the motivic Igusa zeta function, the motivic Milnor fibre and the Hodge-Steenbrink spectrum of f at 0 in terms of topological invariants of (S, 0) subset of (Cd+1, 0)

    Log canonical thresholds of quasi-ordinary hypersurface singularities

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    The log canonical thresholds of irreducible quasi-ordinary hypersurface singularities are computed, using an explicit list of pole candidates for the motivic zeta function found by the last two authors

    El videojuego, un nuevo relato

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    Il s'agit d'une étude de la structure et du contrat du lecture établi dans le vidéo-jeu, d'après les principes opératifs de la Téorie Littéraire et de la Sémiotique. En tant que texte narratif, il donne lieu a un contrat de lecture caractérisé par une série de stratégies qui configurent l'adolescent comme lecteur idéal. La fiction (en rapport avec le registre du récit traditionnel)et la condition interactive (accentuée par des stratégies clefs qui font un effet de vraisemblance) sont les arguments pour expliquer sa consommation.A study of the structure and the contract of reading established in the videogame according to the operating principles in Literary Theory aod Semiotics. As a narrative text it gives rise to the contract of reading typified by a acquience of strategies which shape adolescents as a pattern of readers. Fiction(related to the already known register of the traditional tale)and the interactive condition (stressed by key strategies which develop effects of verisimilitude) are the arguments to explain consumption.Publicad

    Identification of N-terminal protein acetylation and arginine methylation of the voltage-gated sodium channel in end-stage heart failure human heart

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    The α subunit of the cardiac voltage-gated sodium channel, Naᵥ1.5, provides the rapid sodium inward current that initiates cardiomyocyte action potentials. Here, we analyzed for the first time the post-translational modifications of Naᵥ1.5 purified from end-stage heart failure human cardiac tissue. We identified R526 methylation as the major post-translational modification of any Naᵥ1.5 arginine or lysine residue. Unexpectedly, we found that the N terminus of Naᵥ1.5 was: 1) devoid of the initiation methionine, and 2) acetylated at the resulting initial alanine residue. This is the first evidence for N-terminal acetylation in any member of the voltage-gated ion channel superfamily. Our results open the door to explore Naᵥ1.5 N-terminal acetylation and arginine methylation levels as drivers or markers of end-stage heart failure

    Transport and Combustion of Firebrands. Final Report of Grants FG-SP-114 and FG-SP-146 Vol. II

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    A theoretical and experimental study has been carried out on the combustion properties and flight paths of firebrands when they are carried upwards by convective currents and then forwards by the winds. The study has shown that the flight paths of firebrands can be fall decreases continuously as the firebrand burns. Several types of wind tunnels have been developed especially designed to study combustion of firebrands at their final velocity of fall. The study has also show that combustion of firebrands at constant wind speed. The influence of the initial size and initial shape of the firebrands, kind of wood and initial moisture content has been studied, as well as the influence of several types convection columns configurations. Results of these studies enable the calculation of the maximum range of possible fire spread by firebrands of given initial characteristics, once the convective currents above the fire are known as vell as the horizontal wind conditions

    Aplicaciones de la esteganografía en la seguridad informática

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    En la presente investigación se pretende hacer un recorrido histórico de las principales aplicaciones de la esteganografía a la seguridad de la información. Métodos empleados por los griegos para comunicarse en medio de las guerras de modo secreto, el siglo XIV y las técnicas utilizadas por los prisioneros de la Santa Inquisición, los conflictos religiosos presentados en la Inglaterra del siglo XVI y las diferencias entre las hijas del rey Enrique VIII. El primer libro que utilizó en su vocablo la palabra esteganografía y las razones por las que la iglesia católica no lo aceptó, se describen además, métodos utilizados para ocultar información en partituras de música así como los utilizados por africanos para escapar de la esclavitud española. El siglo XX y la llegada de la segunda guerra mundial fueron fundamentales para la aplicación de técnicas esteganográficas. La esteganografía moderna proporciona nuevos medios por los cuales transmitir información. La era moderna de la esteganografía utiliza recursos como imágenes, archivos de audio o video para ocultar información. Los campos de aplicación de la disciplina se expanden, además de los conflictos bélicos se tiene en cuenta técnicas de espionaje industrial, filtrado de información de carácter privado, implementación de software espía y las marcas de agua digitales para garantizar los derechos de autor

    Apposition of iroquois expressing and non-expressing cells leads to cell sorting and fold formation in the Drosophila imaginal wing disc

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    <p>Abstract</p> <p>Background</p> <p>The organization of the different tissues of an animal requires mechanisms that regulate cell-cell adhesion to promote and maintain the physical separation of adjacent cell populations. In the <it>Drosophila </it>imaginal wing disc the <it>iroquois </it>homeobox genes are expressed in the notum anlage and contribute to the specification of notum identity. These genes are not expressed in the adjacent wing hinge territory. These territories are separated by an approximately straight boundary that in the mature disc is associated with an epithelial fold. The mechanism by which these two cell populations are kept separate is unclear.</p> <p>Results</p> <p>Here we show that the Iro-C genes participate in keeping the notum and wing cell populations separate. Indeed, within the notum anlage, cells not expressing Iro-C tend to join together and sort out from their Iro-C expressing neighbours. We also show that apposition of Iro-C expressing and non-expressing cells induces invagination and apico-basal shortening of the Iro-C<sup>- </sup>cells. This effect probably underlies formation of the fold that separates the notum and wing hinge territories. In addition, cells overexpressing a member of the Iro-C contact one another and become organized in a network of thin strings that surrounds and isolates large groups of non-overexpressing cells. The strings appear to exert a pulling force along their longitudinal axis.</p> <p>Conclusion</p> <p>Apposition of cells expressing and non-expressing the Iro-C, as it occurs in the notum-wing hinge border of the <it>Drosophila </it>wing disc, influences cell behaviour. It leads to cell sorting, and cellular invagination and apical-basal shortening. These effects probably account for keeping the prospective notum and wing hinge cell populations separate and underlie epithelial fold formation. Cells that overexpress a member of the Iro-C and that confront non-expressing cells establish contacts between themselves and become organized in a network of thin strings. This is a complex and unique phenotype that might be important for the generation of a straight notum-wing hinge border.</p

    Estimation of volume using the nucleator and lattice points

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    The nucleator is a method to estimate the volume of a particle, i.e., a compact subset of R3, which is widely used in Stereology. It is based on geometric sampling and known to be unbiased. However, the prediction of the variance of this estimator is non-trivial and depends on the underlying sampling scheme. We propose well established tools from quasi-Monte Carlo integration to address this problem. In particular, we show how the theory of reproducing kernel Hilbert spaces can be used for variance prediction and how the variance of estimators based on the nucleator idea can be reduced using lattice (or lattice-like) points. We illustrate and test our results on various examples

    Bibliometric Studies on Rural Female Entrepreneurship: A Metabibliometric Review

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    Entrepreneurship as an important factor for economic development has also become a field of research to understand the causes, effects, successes, failures, characteristics, financing, and other aspects of entrepreneurship. One of the important aspects that studies on entrepreneurship must consider is a gender approach, from that perspective, the research aims to identify trends in research on female entrepreneurship in rural areas based on an analysis of bibliometric studies conducted in this field. A deductive, bibliographic, descriptive, and correlational method was used, and bibliometrics was used as an instrument. The data used were retrieved from three databases: Scopus, WOS, Google Scholar, to identify types, scope and trends of research and provide researchers with a scientific basis on the current situation. A total of 44 papers were considered as population and after using the PRISMA method and excluding studies not related to the research objective and duplicates with the Scopus database, a total of 30 articles were analyzed which constitute the total sample. VOSviewer and SPSS were used for the analysis. The search for documents in the three databases covered the period from 1960 to 2023. The results show, therefore, that bibliometric research on entrepreneurship has not yet addressed other topics beyond a generalization of female entrepreneurship, such as studies on entrepreneurship considering gender, rural geographic spaces, ICT, training, financing, effects, causes, successes, and failures. This allows us to detect that there is an ample scope for developing research not only at the case level, but also at the country level, because for example, in the case of Ecuador we were unable to identify bibliometric studies that analyses these different aspects with a gender focus and spatial intervention of the rural sphere on women's entrepreneurship. On the other hand, research is focused on showing results of female entrepreneurship in urban areas and very little or almost nothing in rural areas, mainly in Latin American countries. It is also observed that they have a recent trend, which would contribute to obtaining indicators and planning future research, as well as contributing to the definition of policies and knowing the discipline state and its progress

    Humanoid synthesis using clifford algebra

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    One of the challenges in the simulation of human motion, either applied to humanoid robots or avatars in virtual environments, is to design a kinematics structure and a set of joint trajectories that move a robot or avatar in a human-like manner. In this paper, a technique is introduced to create accurate humanlike motion with a simplified topology as a reference. Using an optical motion capture system, a finite number of key poses are captured from different subjects performing full body articulated movements. Motion is modeled using the Clifford algebra of dual quaternions and dimensional synthesis techniques are applied to generate the kinematic skeleton of a 3D avatar or robot. The synthesized kinematic skeleton provides location of joints and dimensions of the links forming the limbs, as well as the joint trajectories. Five serial chains constitute our approximation to the human skeleton. Revolute, universal and spherical joints are employed, although other topologies can be used in a similar fashion. Several real datasets are evaluated and results demonstrate that good accuracy can be obtained at interactive rates using the presented methodology. The results show that using simple serial chains in combination with dimensional synthesis suffices to generate the mechanical structure and trajectories of a humanoid robot or 3D avatar mimicking human motion.Postprint (author’s final draft
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