387 resultados para Parallelism


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En el entorno actual, diversas ramas de las ciencias, tienen la necesidad de auxiliarse de la computación de altas prestaciones para la obtención de resultados a relativamente corto plazo. Ello es debido fundamentalmente, al alto volumen de información que necesita ser procesada y también al costo computacional que demandan dichos cálculos. El beneficio al realizar este procesamiento de manera distribuida y paralela, logra acortar los tiempos de espera en la obtención de los resultados y de esta forma posibilita una toma decisiones con mayor anticipación. Para soportar ello, existen fundamentalmente dos modelos de programación ampliamente extendidos: el modelo de paso de mensajes a través de librerías basadas en el estándar MPI, y el de memoria compartida con la utilización de OpenMP. Las aplicaciones híbridas son aquellas que combinan ambos modelos con el fin de aprovechar en cada caso, las potencialidades específicas del paralelismo en cada uno. Lamentablemente, la práctica ha demostrado que la utilización de esta combinación de modelos, no garantiza necesariamente una mejoría en el comportamiento de las aplicaciones. Por lo tanto, un análisis de los factores que influyen en el rendimiento de las mismas, nos beneficiaría a la hora de implementarlas pero también, sería un primer paso con el fin de llegar a predecir su comportamiento. Adicionalmente, supondría una vía para determinar que parámetros de la aplicación modificar con el fin de mejorar su rendimiento. En el trabajo actual nos proponemos definir una metodología para la identificación de factores de rendimiento en aplicaciones híbridas y en congruencia, la identificación de algunos factores que influyen en el rendimiento de las mismas.

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With the advent of High performance computing, it is now possible to achieve orders of magnitude performance and computation e ciency gains over conventional computer architectures. This thesis explores the potential of using high performance computing to accelerate whole genome alignment. A parallel technique is applied to an algorithm for whole genome alignment, this technique is explained and some experiments were carried out to test it. This technique is based in a fair usage of the available resource to execute genome alignment and how this can be used in HPC clusters. This work is a rst approximation to whole genome alignment and it shows the advantages of parallelism and some of the drawbacks that our technique has. This work describes the resource limitations of current WGA applications when dealing with large quantities of sequences. It proposes a parallel heuristic to distribute the load and to assure that alignment quality is mantained.

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In this paper we present the procedure we followed to develop the Italian Super Sense Tagger. In particular, we adapted the English SuperSense Tagger to the Italian Language by exploiting a parallel sense labeled corpus for training. As for English, the Italian tagger uses a fixed set of 26 semantic labels, called supersenses, achieving a slightly lower accuracy due to the lower quality of the Italian training data. Both taggers accomplish the same task of identifying entities and concepts belonging to a common set of ontological types. This parallelism allows us to define effective methodologies for a broad range of cross-language knowledge acquisition tasks.

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Male rats were subjected to "psychological stress" which consisted in 10 sec footshock on the first day followed 24 hr later by a 10 sec stay in the experimental chamber without shock. Intravenous antiserum against alpha-MSH markedly changed the functional state of mesencephalic and hypothalamic DA neurons (assessed by histochemical microfluorimetry) when administered before the second session but not when given before the first session. These observations reveal an interesting parallelism in the temporal characteristics of the effects of alpha-MSH on avoidance behavior and central DA systems.

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We present a new approach for analyzing the turnover rates of Cretaceous radiolarians recorded in pelagic sequences of western Tethys, The analysis of major extinction-radiation events and the fluctuation of diversity are compared with major paleoceanographic events and variation of diversity in dinoflagellates, calcareous nannoplankton and ammonites. There is an extraordinary correlation between biotic changes and sea level changes, temperatures, O, C and Sr isotopes, phosphorus accumulation rates and anoxic episodes. This reveals a predominantly abiotic control on the evolution of radiolarians. The rate of turnover and the diversity through time of two major orders of radiolarians (nassellarians and spumellarians) exhibits (1) the quasi-parallelism of their diversity curves, excluding a direct competition between them, (2) greater resistance of spumellarians to extinction during the early stage of extinction intervals and (3) a stronger post-extinction recovery of nassellarians. Evolutionary rates of radiolarians can be a good means of monitoring global environmental changes and allowing us to understand more clearly the relationship between plankton evolution, climate and pale oceanographic processes.

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"Beauty-contest" is a game in which participants have to choose, typically, a number in [0,100], the winner being the person whose number is closest to a proportion of the average of all chosen numbers. We describe and analyze Beauty-contest experiments run in newspapers in UK, Spain, and Germany and find stable patterns of behavior across them, despite the uncontrollability of these experiments. These results are then compared with lab experiments involving undergraduates and game theorists as subjects, in what must be one of the largest empirical corroborations of interactive behavior ever tried. We claim that all observed behavior, across a wide variety of treatments and subject pools, can be interpretedas iterative reasoning. Level-1 reasoning, Level-2 reasoning and Level-3 reasoning are commonly observed in all the samples, while the equilibrium choice (Level-Maximum reasoning) is only prominently chosen by newspaper readers and theorists. The results show the empirical power of experiments run with large subject-pools, and open the door for more experimental work performed on the rich platform offered by newspapers and magazines.

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Remote sensing spatial, spectral, and temporal resolutions of images, acquired over a reasonably sized image extent, result in imagery that can be processed to represent land cover over large areas with an amount of spatial detail that is very attractive for monitoring, management, and scienti c activities. With Moore's Law alive and well, more and more parallelism is introduced into all computing platforms, at all levels of integration and programming to achieve higher performance and energy e ciency. Being the geometric calibration process one of the most time consuming processes when using remote sensing images, the aim of this work is to accelerate this process by taking advantage of new computing architectures and technologies, specially focusing in exploiting computation over shared memory multi-threading hardware. A parallel implementation of the most time consuming process in the remote sensing geometric correction has been implemented using OpenMP directives. This work compares the performance of the original serial binary versus the parallelized implementation, using several multi-threaded modern CPU architectures, discussing about the approach to nd the optimum hardware for a cost-e ective execution.

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Quelles représentations de la schizophrénie les psychiatres vont-ils construire à travers l'étude des écrits asilaires des patients et des scientifiques dans la première moitié du XXème siècle? Le psychiatre helvétique Hans Steck (1891-1980), qui a travaillé à l'Asile psychiatrique de Cery de 1920 à 1960 et qui s'est fait connaître du public grâce à l'oeuvre d'Aloïse Corbaz, reconnue comme auteure d'art brut par Jean Dubuffet en 1945, constitue le fil rouge de la thèse. Dans le contexte des mouvements tels que Γ "art psychopathologique" et Γ "art brut", Steck étudie les théories de "la mentalité primitive et les peintures magiques des schizophrènes". En 1927, il se tourne vers les théories évolutionnistes de la régression et les premières études de Lévy-Bruhl pour avancer l'idée qu'il existe un "parallélisme schizo-primitif'. Puis il développe des explications de la pensée délirante, à partir des théories exposées lors du Premier Congrès International de Psychiatrie en 1950. Enfin, adoptant la perspective phénoménologique, il explique que "la fonction de l'art et la fonction du délire visent à reconstituer un monde viable pour le malade". En ce sens, l'expression artistique, bien que n'entrant pas dans le champ de la psychothérapie, fournit des indicateurs de l'état psychique du malade en même temps qu'elle contribue à son bien-être. Sont abordés les problèmes concernant la reconnaissance de Γ "auteur" interné, dont les oeuvres appartiennent soit aux archives médicales, soit au musée. La pérennité des critères qui définissent les oeuvres d'"art psychopathologique" ou d'"art brut" est également mise en question. Enfin, le rôle essentiel de l'écriture à l'hôpital, tant pour les patients que pour les soignants, fait l'objet de nombreux développements. - What representations of schizophrenia have psychiatrists been constructing when studying writings by patients and scientists in mental asylums in the first half of the 20th century? The Swiss psychiatrist Hans Steck (1891-1980) is the protagonist of this dissertation. From 1920 to 1960, he has been working at the "Asile psychiatrique de Cery" near Lausanne. Steck is known thanks to the paintings of Aloïse Corbaz, an artist recognized by Jean Dubuffet as belonging to the "art brut" movement in 1945. In the context of movements like "art psychopathologique" and "art brut," Steck studies theories of "primitive character and magic paintings of schizophrenics." In 1927, Steck engages with theories of regression and Lévy-Bruhl's early studies in order to push the idea of a "parallelism schizo-primitif." On the occasion of the First International Congress of psychiatry held in Paris in 1950, Steck develops explanations for the "pensée délirante." Finally, turning to a phenomenological point of view, he explains, "the function of art and the function of the delusion help the patient to reconstruct a viable environment for the sick person." In this way, artistic expression is not thought of as a psychotherapeutical means, but provides insight into the state of mind of a mentally sick person at the same time as contributing to his well-being. The dissertation discusses whether the "author's" work belongs in medical archives or museums. The continuity of "psychopathological art" and "art brut" criteria will be discussed. Finally, the essential role that writing played in the hospital for the patients as well as for the medical staff is presented.

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Actualment un típic embedded system (ex. telèfon mòbil) requereix alta qualitat per portar a terme tasques com codificar/descodificar a temps real; han de consumir poc energia per funcionar hores o dies utilitzant bateries lleugeres; han de ser el suficientment flexibles per integrar múltiples aplicacions i estàndards en un sol aparell; han de ser dissenyats i verificats en un període de temps curt tot i l’augment de la complexitat. Els dissenyadors lluiten contra aquestes adversitats, que demanen noves innovacions en arquitectures i metodologies de disseny. Coarse-grained reconfigurable architectures (CGRAs) estan emergent com a candidats potencials per superar totes aquestes dificultats. Diferents tipus d’arquitectures han estat presentades en els últims anys. L’alta granularitat redueix molt el retard, l’àrea, el consum i el temps de configuració comparant amb les FPGAs. D’altra banda, en comparació amb els tradicionals processadors coarse-grained programables, els alts recursos computacionals els permet d’assolir un alt nivell de paral•lelisme i eficiència. No obstant, els CGRAs existents no estant sent aplicats principalment per les grans dificultats en la programació per arquitectures complexes. ADRES és una nova CGRA dissenyada per I’Interuniversity Micro-Electronics Center (IMEC). Combina un processador very-long instruction word (VLIW) i un coarse-grained array per tenir dues opcions diferents en un mateix dispositiu físic. Entre els seus avantatges destaquen l’alta qualitat, poca redundància en les comunicacions i la facilitat de programació. Finalment ADRES és un patró enlloc d’una arquitectura concreta. Amb l’ajuda del compilador DRESC (Dynamically Reconfigurable Embedded System Compile), és possible trobar millors arquitectures o arquitectures específiques segons l’aplicació. Aquest treball presenta la implementació d’un codificador MPEG-4 per l’ADRES. Mostra l’evolució del codi per obtenir una bona implementació per una arquitectura donada. També es presenten les característiques principals d’ADRES i el seu compilador (DRESC). Els objectius són de reduir al màxim el nombre de cicles (temps) per implementar el codificador de MPEG-4 i veure les diferents dificultats de treballar en l’entorn ADRES. Els resultats mostren que els cícles es redueixen en un 67% comparant el codi inicial i final en el mode VLIW i un 84% comparant el codi inicial en VLIW i el final en mode CGA.

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The cichlids of East Africa are renowned as one of the most spectacular examples of adaptive radiation. They provide a unique opportunity to investigate the relationships between ecology, morphological diversity, and phylogeny in producing such remarkable diversity. Nevertheless, the parameters of the adaptive radiations of these fish have not been satisfactorily quantified yet. Lake Tanganyika possesses all of the major lineages of East African cichlid fish, so by using geometric morphometrics and comparative analyses of ecology and morphology, in an explicitly phylogenetic context, we quantify the role of ecology in driving adaptive speciation. We used geometric morphometric methods to describe the body shape of over 1000 specimens of East African cichlid fish, with a focus on the Lake Tanganyika species assemblage, which is composed of more than 200 endemic species. The main differences in shape concern the length of the whole body and the relative sizes of the head and caudal peduncle. We investigated the influence of phylogeny on similarity of shape using both distance-based and variance partitioning methods, finding that phylogenetic inertia exerts little influence on overall body shape. Therefore, we quantified the relative effect of major ecological traits on shape using phylogenetic generalized least squares and disparity analyses. These analyses conclude that body shape is most strongly predicted by feeding preferences (i.e., trophic niches) and the water depths at which species occur. Furthermore, the morphological disparity within tribes indicates that even though the morphological diversification associated with explosive speciation has happened in only a few tribes of the Tanganyikan assemblage, the potential to evolve diverse morphologies exists in all tribes. Quantitative data support the existence of extensive parallelism in several independent adaptive radiations in Lake Tanganyika. Notably, Tanganyikan mouthbrooders belonging to the C-lineage and the substrate spawning Lamprologini have evolved a multitude of different shapes from elongated and Lamprologus-like hypothetical ancestors. Together, these data demonstrate strong support for the adaptive character of East African cichlid radiations.

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La dècada de 1980 va significar un punt i a part per als governs metropolitans. Després de viure una època daurada durant els 60 i 70, la reestructuració del sistema politicoeconòmic va comportar que les estructures de govern metropolità fossin qüestionades i fins i tot suprimides. Quan tot semblava indicar que restarien només com a record, la lògica de competència entre grans ciutats i la necessitat de reinventar-se en base a un desenvolupament sostenible va suposar un inesperat renaixement de la política metropolitana. Si fins aleshores la seva necessitat s'havia justificat bàsicament des d'un punt de vista funcional, seguint pautes tecnòcrates i burocratitzades, la nova metropolítica se centra en la competitivitat i en la sostenibilitat, alhora que posa èmfasi en assajar mètodes de governança. Londres, ciutat que presenta certs paral·lelismes històrics amb Barcelona, ha estat una ciutat pionera i de la seva experiència es pot aprendre per la capital catalana

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The past few decades have seen a considerable increase in the number of parallel and distributed systems. With the development of more complex applications, the need for more powerful systems has emerged and various parallel and distributed environments have been designed and implemented. Each of the environments, including hardware and software, has unique strengths and weaknesses. There is no single parallel environment that can be identified as the best environment for all applications with respect to hardware and software properties. The main goal of this thesis is to provide a novel way of performing data-parallel computation in parallel and distributed environments by utilizing the best characteristics of difference aspects of parallel computing. For the purpose of this thesis, three aspects of parallel computing were identified and studied. First, three parallel environments (shared memory, distributed memory, and a network of workstations) are evaluated to quantify theirsuitability for different parallel applications. Due to the parallel and distributed nature of the environments, networks connecting the processors in these environments were investigated with respect to their performance characteristics. Second, scheduling algorithms are studied in order to make them more efficient and effective. A concept of application-specific information scheduling is introduced. The application- specific information is data about the workload extractedfrom an application, which is provided to a scheduling algorithm. Three scheduling algorithms are enhanced to utilize the application-specific information to further refine their scheduling properties. A more accurate description of the workload is especially important in cases where the workunits are heterogeneous and the parallel environment is heterogeneous and/or non-dedicated. The results obtained show that the additional information regarding the workload has a positive impact on the performance of applications. Third, a programming paradigm for networks of symmetric multiprocessor (SMP) workstations is introduced. The MPIT programming paradigm incorporates the Message Passing Interface (MPI) with threads to provide a methodology to write parallel applications that efficiently utilize the available resources and minimize the overhead. The MPIT allows for communication and computation to overlap by deploying a dedicated thread for communication. Furthermore, the programming paradigm implements an application-specific scheduling algorithm. The scheduling algorithm is executed by the communication thread. Thus, the scheduling does not affect the execution of the parallel application. Performance results achieved from the MPIT show that considerable improvements over conventional MPI applications are achieved.

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During the fieldwork in the medieval fortification of Ausa (Gipuzkoa), a vast amount of sherds from several pottery artifacts featured by a cylindrical body has been found out. They presumably had the same function in contexts dated from the first half of xiv century. Although it has not been possible to reconstruct any of these artefacts, the study of the sherds allows us to think that they would have formed some sort of big-sized horn. This high-sounding instrument, which has been frequently reproduced in iconographic references, does not have at this moment any direct parallelism in Hispanic contexts, despite being plentiful of references to similar objects in medieval ranges from Provence and Languedoc. By introducing these artefacts from different approaches, we aim to go over the scarce knowledge of these instruments, whose evidence lets us to believe in their widespread distribution all over the landscape in several material contexts from Medieval Ages.

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During the fieldwork in the medieval fortification of Ausa (Gipuzkoa), a vast amount of sherds from several pottery artifacts featured by a cylindrical body has been found out. They presumably had the same function in contexts dated from the first half of xiv century. Although it has not been possible to reconstruct any of these artefacts, the study of the sherds allows us to think that they would have formed some sort of big-sized horn. This high-sounding instrument, which has been frequently reproduced in iconographic references, does not have at this moment any direct parallelism in Hispanic contexts, despite being plentiful of references to similar objects in medieval ranges from Provence and Languedoc. By introducing these artefacts from different approaches, we aim to go over the scarce knowledge of these instruments, whose evidence lets us to believe in their widespread distribution all over the landscape in several material contexts from Medieval Ages.

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We present an algorithm for the computation of reducible invariant tori of discrete dynamical systems that is suitable for tori of dimensions larger than 1. It is based on a quadratically convergent scheme that approximates, at the same time, the Fourier series of the torus, its Floquet transformation, and its Floquet matrix. The Floquet matrix describes the linearization of the dynamics around the torus and, hence, its linear stability. The algorithm presents a high degree of parallelism, and the computational effort grows linearly with the number of Fourier modes needed to represent the solution. For these reasons it is a very good option to compute quasi-periodic solutions with several basic frequencies. The paper includes some examples (flows) to show the efficiency of the method in a parallel computer. In these flows we compute invariant tori of dimensions up to 5, by taking suitable sections.