Analytic model of a cache-only memory architecture

An approximate analytic model of a shared memory multiprocessor with a Cache Only Memory Architecture (COMA), the busbased Data Difussion Machine (DDM), is presented and validated. It describes the timing and interference in the system as a function of the hardware, the protocols, the topology and the workload. Model results have been compared to results from an independent simulator. The comparison shows good model accuracy specially for non-saturated systems, where the errors in response times and device utilizations are independent of the number of processors and remain below 10% in 90% of the simulations. Therefore, the model can be used as an average performance prediction tool that avoids expensive simulations in the design of systems with many processors.

Relating goal scheduling, precedence, and memory management in and-parallel execution of logic programs

The interactions among three important issues involved in the implementation of logic programs in parallel (goal scheduling, precedence, and memory management) are discussed. A simplified, parallel memory management model and an efficient, load-balancing goal scheduling strategy are presented. It is shown how, for systems which support "don't know" non-determinism, special care has to be taken during goal scheduling if the space recovery characteristics of sequential systems are to be preserved. A solution based on selecting only "newer" goals for execution is described, and an algorithm is proposed for efficiently maintaining and determining precedence relationships and variable ages across parallel goals. It is argued that the proposed schemes and algorithms make it possible to extend the storage performance of sequential systems to parallel execution without the considerable overhead previously associated with it. The results are applicable to a wide class of parallel and coroutining systems, and they represent an efficient alternative to "all heap" or "spaghetti stack" allocation models.

Dopamine receptor 4 promoter polymorphism modulates memory and neuronal responses to salience

Animal models and human functional imaging data implicate the dopamine system in mediating enhanced encoding of novel stimuli into human memory. A separate line of investigation suggests an association between a functional polymorphism in the promoter region for the human dopamine 4 receptor gene (DRD4) and sensitivity to novelty. We demonstrate, in two independent samples, that the -521Cmayor queT DRD4 promoter polymorphism determines the magnitude of human memory enhancement for contextually novel, perceptual oddball stimuli in an allele dose-dependent manner. The genotype-dependent memory enhancement conferred by the C allele is associated with increased neuronal responses during successful encoding of perceptual oddballs in the ventral striatum, an effect which is again allele dose-dependent. Furthermore, with repeated presentations of oddball stimuli, this memory advantage decreases, an effect mirrored by adaptation of activation in the hippocampus and substantia nigra/ventral tegmental area in C carriers only. Thus, a dynamic modulation of human memory enhancement for perceptually salient stimuli is associated with activation of a dopaminergic-hippocampal system, which is critically dependent on a functional polymorphism in the DRD4 promoter region.

La memoria en el proceso creativo de Juan Muñoz = Memory in the creative process of Juan Muñoz

Esta tesis integra un estudio reflexivo sobre la relación de dependencia entre la creación y la memoria a través del análisis de la última obra del escultor Juan Muñoz: Double Bind (Tate Modern, Londres, 2001). Desde esta posición es obligado replantear el análisis de la obra, lo que hace necesario su estudio cubriendo el mayor espectro posible de información accesible más allá de la obra en sí, para aproximarse a la convergencia entre memoria y creación. La perspectiva de análisis propuesta abre camino a nuevas consideraciones so¬bre la relevancia del conocimiento en el desarrollo del proceso creativo. Este análisis no debe tan sólo suponer una aportación al conocimiento del trabajo de Juan Muñoz. Debe también desprenderse de él la innegable participación y necesaria lectura del pasado en el presente. La amnesia de los tiempos pasados impide completar el atlas de imágenes en las que se apoya la creación impidiendo el conocimiento del origen de las fuentes de inspi¬ración y las bases de la creación de una determinada obra. Este hecho limita y distorsiona sus posibles interpretaciones. Pretendo un acercamiento al entendimiento de la forma de mirar y de crear a través del tiempo que es memoria. La memoria tiene un cometido de crucial importancia para la actividad mental y juega un papel fundamental en la conducta y en la creación. La obra es el resultado de la búsqueda de una idea que exprese algo que el creador no puede ex¬presar de otra manera. Es la necesidad de expresar las ideas mediante un lenguaje que se desarrolla en el tiempo y en el espacio, reflejo del ser que responde al pensamiento. Es una forma de experiencia donde subyacen las sendas del pasado y donde se plantea el futuro. Sólo el creador accede a la obra desde dentro, el observador llega a ella desde el exterior y mediante su propia subjetividad. Las obras son formas de experiencia de sus autores, comunicar el mensaje de dicha experiencia supone por tanto interpretar. Persiguiendo la necesidad de saber y entender, pretender explicar el sentido de una cosa implica una apreciación intencionada asociada al entendimiento del intérprete. Las obras son produc¬tos que portan un mensaje y que contienen en su estructura las trazas del tiempo vivido por su creador. Si se quiere adquirir un acercamiento que represente la posición de un autor, será necesario no solo mirar a través de ella, si no introducirse en el contexto de su historia. Mirar hacia atrás, hacia la profundidad del presente para tener conciencia del pensamiento presente y futuro. Recorrer de este modo la instalación Double Bind de Juan Muñoz proporciona una síntesis de sus preocupaciones e intereses a la vez que aporta un conocimiento no necesariamente inmediato, pero relevante y trascendente de la obra, su creador y la historia. ABSTRACT This thesis comprises a reflective study of the dependence relationship between creation and memory through the analysis of the latest work by the sculptor Juan Muñoz: Double Bind (Tate Modern, London, 2001). From this position, it is mandatory to rethink the analysis of the work, making it necessary to cover the widest possible range of information available beyond the work itself, in order to obtain a closer view of the convergence between memory and creation. The proposed analytical approach opens up new considerations on the relevance of knowledge during the development of the creative process. This analysis should not only make a contribution to the knowledge of the work of Juan Muñoz. It should also infer the undeniable involvement and the necessary reading of the past in the present. Amnesia regarding past makes it impossible to complete the atlas of images on which the creation is based, blocking knowledge of the origin of the sources of inspiration and the basis for the creation of a specific work. This fact limits and distorts its possible interpretations. My intention is an approach to how to understand memory as the way of looking and creating over time. Memory has a crucial role to mental activity and plays a key role in behaviour and creation. The work is the result of finding an idea that expresses something that the creator can not express otherwise. It is the need to express ideas by means of a language that develops throughout time and space, a reflection of the being that responds to the thought. It is a way of experience underlying the paths of the past and where the future is set out. Only the creator can access the work from the inside. The observer sees it from the outside and in accordance with his/her own subjectivity. The works form a part of the experience of their authors, thus implying the interpretation of the message of their experience being passed on. The pursuit of knowledge and understanding, and trying to explain the meaning of something implies a deliberate appreciation associated with the understanding of the interpreter. The works are products bearing a message and containing in their structure traces of the time lived by their creator. If one wants to come close to what the author’s posture represents, it will not only be necessary to penetrate it, but also to introduce oneself into the context of its history. Take a look back, towards the depth of the present in order to become aware of present and future thinking. To go across the installation of Double Bind by Juan Muñoz in this way offers a synthesis of his concerns and interests while also providing a not necessarily immediate knowledge, but one which is relevant and important to the work, its creator and history.