Cosmological simulations are used by astronomers to investigate large scale structure formation and galaxy evolution. Structure nding, that is, the discovery of gravitationally-bound objects such as dark matter halos, is a crucial step in many such simulations. During recent years, advancing computational capacity has lead to halo-nders needing to manage increasingly larger simulations. As a result, many multi-core solutions have arisen in an attempt to process these simulations more eciently. However, a many-core approach to the problem using graphics processing units (GPUs) appears largely unexplored. Since these simulations are inherently n-body problems, they contain a high degree of parallelism, which makes them very well suited to a GPU architecture. Therefore, it makes sense to determine the potential for further research in halo-nding algorithms on a GPU. We present a number of modified algorithms, for accelerating the identication of halos and sub-structures, using entry-level graphics hardware. The algorithms are based on an adaptive hierarchical renement of the friends-of-friends (FoF) method using six phase-space dimensions: This allows for robust tracking of sub-structures. These methods are highly amenable to parallel implementation and run on GPUs. We implemented four separate systems; two on GPUs and two on CPUs. The first system for both CPU and GPU was implemented as a proof of concept exercise to familiarise us with the problem: These utilised minimum spanning trees (MSTs) and brute force methods. Our second implementation, for the CPU and GPU, capitalised on knowledge gained from the proof of concept applications, leading us to use kd-trees to efficiently solve the problem. The CPU implementations were intended to serve as benchmarks for our GPU applications. In order to verify the efficacy of the implemented systems, we applied our halo finders to cosmological simulations of varying size and compared the results obtained to those given by a widely used FoF commercial halo-finder. To conduct a fair comparison, CPU benchmarks were implemented using well-known libraries optimised for these calculations. The best performing implementation, with minimal optimisation, used kd-trees on the GPU. This achieved a 12x speed-up over our CPU implementation, which used similar methods. The same GPU implementation was compared with a current, widely-used commercial halo finder FoF system, and achieved a 2x speed-up for up to 5 million particles. Results suggest a scalable solution, where speed-up increases with the size of dataset used. We conclude that there is great potential for future research into an optimised kd-tree implementation on graphics hardware for the problem of structure finding in cosmological simulations.

Lic.-avhandling Linköping : Linköpings universitet, 2006.

Diss. Umeå : Umeå universitet, 2007.

Thesis (Ph. D.)--University of Washington, 2004. / Vita. Includes bibliographical references (leaves 100-109).

Thesis (Ph. D.)--Ohio State University, 2005. / Title from first page of PDF file. Document formatted into pages; contains xvii, 216 p.; also includes graphics (some col.). Includes bibliographical references. Available online via OhioLINK's ETD Center

Diss. Karlstad : Karlstads universitet, 2009.

La levure Candida albicans présente une tolérance élevée aux réarrangements de son génome et en particulier, aux pertes d’hétérozygotie (LOH). Ces LOH sont le plus souvent le résultat de la réparation d’une cassure double-brin de l’ADN (DNA DSB) et jouent un rôle important dans différents aspects de la biologie de C. albicans. Afin d’étudier les mécanismes moléculaires à l’origine des LOH, nous avons combiné un système d’induction d’un DNA DSB par la méganucléase I-SceI et un système rapporteur de LOH optimisé pour l’analyse par FACS. La surexpression de I-SceI entraine une forte augmentation du taux de LOH, principalement des conversions géniques. La caractérisation des cellules ayant subi une LOH a permis d’identifier des allèles récessifs délétères et létaux présents à l’état hétérozygote dans le génome de la souche de laboratoire de C. albicans. Ces allèles influent sur la nature des LOH observés suite à un DNA DSB. Nous avons également caractérisé la fidélité de la réparation d’un DNA DSB induit par I-SceIchez C. albicans. Cette étude a permis de décrire des recombinaisons complexes et inattendues se déroulant pendant les événements de break-induced replication et de conversions géniques avec crossover. En parallèle, une collection de 564 plasmides de surexpression pour des gènes impliqués dans les voies de signalisation et dans l’intégrité du génome et de la paroi a été transformée dans une souche possédant les deux systèmes mentionnés ci-dessus. L’analyse des transformants dans des conditions ou non d’expression de I-SceI a permis d’identifier des gènes dont la surexpression augmente le taux basal de LOH ou diminue le taux de LOH élevé du à l’expression d’I-SceI. / The Candida albicans genome displays a high tolerance to rearrangements, notably loss-ofheterozygosity (LOH) events. These events most often result from the repair of DNA double-strandbreaks (DSBs) and are known to play an important role in different aspects of C. albicans biology.To study the molecular mechanisms leading to LOH, we have combined an I-SceI meganuclease-dependent DSB-inducing system with a FACS-optimized reporter system of LOH. Our results show that expression of I-SceI leads to a dramatic increase in the frequency of LOH events,mainly gene conversion events. Characterization of cells having undergone a LOH led us to identify recessive lethal and deleterious alleles present in the heterozygous state in the genome of the C.albicans laboratory strain. These alleles influence the nature of the LOH events that are observed following a DSB. We also characterized the fidelity of the repair following an I-SceI-induced DNA DSB. This revealed unexpected complex recombination events occurring upon both break-induced replication and gene conversion with crossover repair events. In parallel, a collection of 564 over expression plasmids for genes involved in signaling pathways, genome integrity and cell wall integrity has been transformed in a C. albicans strainharboring the I-SceI-dependent DSB-inducing system and FACS-optimized LOH reporter. Analyses of the resulting transformants under conditions that allowed fro I-SceI expression or not, led to the identification of genes whose overexpression results either in an increase of the basal LOH rate or in areduction of the high LOH frequency associated to I-SceI expression.

This thesis provides an account of the metaphors of cancer in a comparable English and Spanish corpus of 300 press popularisation articles. The aim is to identify relevant source domains that are employed in these articles to conceptualise the disease. Although a number of studies have explored the use of WAR metaphors in the discourse on cancer, there is still little understanding of the actual way cancer is presented metaphorically to the lay public in the press or of the range of source domains that conceptualise the target domain. Thus, in addition to the WAR, VIOLENCE AND AGGRESSION source domain, this study focuses on other metaphorical systems exploited to elucidate such aspects as metastasis, apoptosis, cancer treatments and cancer research. A text analysis was carried out with the aid of a corpus software program. The metaphors in the two subcorpora were compared quantitatively and qualitatively for cross-cultural differences in terms of their functions and patterning. Although cancer knowledge is popularised through similar metaphorical expressions, subtle differences have been identified in terms of metaphor density, choice of metaphor and the functions performed by these expressions. / Esta tesis describe las metáforas del cáncer en un corpus bilingüe inglés-español de 300 artículos de divulgación en la prensa. El objetivo ha sido identificar los distintos dominios fuente relevantes que se emplean en la conceptualización de la enfermedad. Aunque varios trabajos han estudiado las metáforas bélicas utilizadas en el discurso del cáncer, todavía se sabe poco de la forma en la que el cáncer se representa mediante metáforas al público lego y de la variedad de dominios fuente que conceptualizan el dominio meta. Así, además del dominio fuente de la GUERRA, VIOLENCIA Y AGRESIÓN, este estudio se centra en otros sistemas metafóricos empleados para clarificar diversos aspectos como la metástasis, la apoptosis, los tratamientos del cáncer y la investigación oncológica. El análisis textual se ha realizado con la ayuda de un programa informático de análisis de corpus textuales. Las metáforas de ambos subcorpus se han comparado cuantitativa y cualitativamente con el fin de identificar diferencias transculturales en relación a las funciones y a los patrones de las mismas. Aunque el conocimiento sobre el cáncer se divulga a través de expresiones metafóricas similares, se pueden apreciar pequeñas diferencias en relación a la densidad metafórica, la elección de las metáforas y las funciones que estas expresiones desempeñan.

Material addicional: http://hdl.handle.net/10230/25939 / Aquesta tesi estudia llibres de text per a no catalanoparlants adults publicats entre 2005 i 2015 des d’una perspectiva crítica. Els dos objectius principals són: (a) explorar de quina forma el context macro influencia la naturalesa dels materials objecte d’estudi, i (b) examinar la relació entre el contingut dels llibres i les condicions socioeconòmiques de l’actual fase del capitalisme. Per assolir el primer objectiu, fem una anàlisi crítica de l’evolució de l’ensenyament i materials de llengües estrangeres en relació amb el seu context macro. L’estudi suggereix que les polítiques del Consell d’Europa tenen un gran impacte en l’ensenyament de llengües estrangeres, i també en els llibres de català per a no catalanoparlants adults. Aquesta institució ha promogut l’ensenyament comunicatiu d’una llengua instrumental amb un seguit de projectes que han dut a un accelerat procés d’estandardització, centralització i homogeneïtzació de l’ensenyament i els materials didàctics. Les propostes del Consell d’Europa s’han desenvolupat en sintonia amb l’esperit mercantilista que el neoliberalisme propugna per a totes les esferes de la vida. Per atènyer el segon objectiu, es desenvolupa una anàlisi quantitativa del contingut del corpus seguida d’una de més interpretativa centrada en els móns de la feina, els viatges i l’habitatge. Els resultats apunten que les pràctiques i valors neoliberals solen aparèixer des d’una perspectiva positiva, com a fenòmens naturals, sense que s’hi mencionin aspectes negatius o limitacions. Els llibres, a més, proposen un tipus d’activitats que podrien contribuir a desenvolupar entre els aprenents els rols de consumidors i treballadors emprenedors i flexibles que l’ordre socioeconòmic vigent requereix. / This thesis studies contemporary course books for Catalan as a foreign language published from 2005 to 2015 from a critical perspective. Two main objectives of this study are: (a) to describe in what way the macro context influences the nature of the studied materials, and (b) to examine the relationship between the content of the course books and the socio-economical conditions in the latest phase of capitalism. In order to accomplish the first objective, the study explores the ways foreign and second language learning processes and textbook design evolved relating them to the wider macro context. The study suggests that the language policies from the Council of Europe have a major impact on foreign language teaching in Europe and are subsequently influencing on curriculum and course book design of Catalan as a foreign language. This institution has been actively involved in creation and promotion of the communicative language teaching with the emphasis on instrumental language. It has also been a firm promoter of the processes of standardization, centralization and homogenization of foreign language learning and course book design. The Council of Europe’s projects for language learning, have been developed in accord with the mercantilist spirit of neoliberalism that extends to all spheres of live. To accomplish the second objective a quantitative analysis of the corpus was developed followed by a more interpretative one centered on the topics of work, housing and travel. The results suggest that practices and values of neoliberalism usually appear in a positive, naturalized way without mentioning their negative aspects or limitations. Moreover, the course books analyzed propose activities which support and develop the roles of consumers and entrepreneurs in students that the current economic order requires.

This PhD dissertation examines how educational practice mediates learning the language of instruction with immigrant students in a linguistic support classroom in Catalonia. From a socioconstructivist theoretical approach, educational practice was examined at two levels: at the macro-level, we identify the forms of joint activity which are developed during the different learning tasks , and at the micro-level, the dialogue at the classroom was examined, focusing on the semiotic resources through which the teacher establishes and maintains intersubjectivity with students on the language activities. The research results show three key issues in the development of educational practice: the teaching of language is a shared reflective process around the language as "a procedure", second, this process is supported by the transitions between different forms and ways of using language, and finally, the educational practice is characterized by the orchestration of discursive strategies “in dyad” with other discursive strategies “in group”. Thereby the teacher's speech become adjusted to different levels of knowledge of the language school that the students possess. / El cambio del bilingüismo al plurilingüismo probablemente es la mayor transformación que ha experimentado la escuela en Catalunya en los últimos diez años. Esta tesis doctoral presenta un estudio cualitativo que examina cómo la práctica educativa media en el aprendizaje del catalán con alumnos inmigrantes multilingües a su llegada a Catalunya. Desde una aproximación socio-constructivista analizamos la mediación pedagógica en dos niveles de análisis: en el nivel global, identificamos las formas de organización de la actividad conjunta en las diferentes tareas de aprendizaje de la lengua, y en el nivel local, analizamos el diálogo en clase, focalizándonos en los recursos semióticos y discursivos por medio de los cuales la maestra establece y mantiene intersubjetividad con los alumnos en relación con el contenido de enseñanza. Los resultados muestran tres cuestiones fundamentales sobre la práctica educativa en el aula de acogida lingüística: enseñar la lengua constituye un proceso reflexivo continuado entorno al lenguaje como procedimiento, este proceso se sostiene mediante la negociación compartida de transiciones entre formas y modos diferentes de emplear el lenguaje en diferentes situaciones y contextos, y por último, la práctica educativa se caracteriza por la orquestación de estrategias comunicativas diádico-grupales, las cuáles permiten crear condiciones de inclusión para los alumnos que tienen un menor conocimiento del catalán en relación a aquellos otros alumnos que poseen un mayor conocimiento de esta lengua.