Galactic Chemical Evolution and the abundances of lithium, beryllium and boron

A LiBeB evolution model including Galactic Cosmic Ray nucleosynthesis, the $\nu$-process, novae, AGB and C-stars is presented. We have included Galactic Cosmic Ray Nucleosynthesis (GCRN) in a complete Chemical Evolution Model that takes into account 76 stable isotopes from hydrogen to zinc. Any successful LiBeB evolution model should also be compatible with other observational constraints like the age-metallicity relation, the G-dwarf distribution or the evolution of other elements. At the same time, we have checked how different would be a model that took into account the last observations by Wakker et al. (1999) of metal-enriched clouds falling onto the disk, from a primordial infall model.Comment: 2 pages, 2 figures. To appear in `Cosmic Evolution' Conference at IAp, Paris 13-17 Nov 200

A cost-effective clustered architecture

In current superscalar processors, all floating-point resources are idle during the execution of integer programs. As previous works show, this problem can be alleviated if the floating-point cluster is extended to execute simple integer instructions. With minor hardware modifications to a conventional superscalar processor, the issue width can potentially be doubled without increasing the hardware complexity. In fact, the result is a clustered architecture with two heterogeneous clusters. We propose to extend this architecture with a dynamic steering logic that sends the instructions to either cluster. The performance of clustered architectures depends on the inter-cluster communication overhead and the workload balance. We present a scheme that uses run-time information to optimise the trade-off between these figures. The evaluation shows that this scheme can achieve an average speed-up of 35% over a conventional 8-way issue (4 int+4 fp) machine and that it outperforms the previously proposed one.Peer ReviewedPostprint (published version

Statistical analysis and comparison of 2T and 3T1D e-DRAM minimum energy operation

Bio-medical wearable devices restricted to their small-capacity embedded-battery require energy-efficiency of the highest order. However, minimum-energy point (MEP) at sub-threshold voltages is unattainable with SRAM memory, which fails to hold below 0.3V because of its vanishing noise margins. This paper examines the minimum-energy operation point of 2T and 3T1D e-DRAM gain cells at the 32-nm technology node with different design points: up-sizing transistors, using high- V th transistors, read/write wordline assists; as well as operating conditions (i.e., temperature). First, the e-DRAM cells are evaluated without considering any process variations. Then, a full-factorial statistical analysis of e-DRAM cells is performed in the presence of threshold voltage variations and the effect of upsizing on mean MEP is reported. Finally, it is shown that the product of the read and write lengths provides a knob to tradeoff energy-efficiency for reliable MEP energy operation.Peer ReviewedPostprint (author's final draft

Replacing 6T SRAMs with 3T1D DRAMs in the L1 data cache to combat process variability

With continued technology scaling, process variations will be especially detrimental to six-transistor static memory structures (6T SRAMs). A memory architecture using three-transistor, one-diode DRAM (3T1D) cells in the L1 data cache tolerates wide process variations with little performance degradation, making it a promising choice for on-chip cache structures for next-generation microprocessors.Peer ReviewedPostprint (published version

Strategies to enhance the 3T1D-DRAM cell variability robustness beyond 22 nm

3T1D cell has been stated as a valid alternative to be implemented on L1 memory cache to substitute 6T, highly affected by device variability as technology dimensions are reduced. In this work, we have shown that 22 nm 3T1D memory cells present significant tolerance to high levels of device parameter fluctuation. Moreover, we have observed that when variability is considered the write access transistor becomes a significant detrimental element on the 3T1D cell performance. Furthermore, resizing and temperature control have been presented as some valid strategies in order to mitigate the 3T1D cell variability.Peer ReviewedPostprint (author's final draft

Políticas locales de consumo para superar el ideal hiperconsumista

Este capítulo es fruto de la investigación encargada por el Área de Salud Pública y Consumo de la Diputación de Barcelona, editada en: Brugué, Q., Canal, R. y Marquilles, B. (2010): «Informe sobre les polítiques locals de consum a la província de Barcelona (1999-2008)», Diputació de Barcelona, Col. Documents de Treball, Sèrie Desenvolupament Econòmic 11

¿Queremos decir lo mismo cuando hablamos de participación? : Perspectivas de activistas, técnicos y políticos locales reveladas con metodología Q

El artículo analiza y compara el pensamiento en torno a la participación ciudadana de políticos, técnicos y activistas de la esfera municipal de Madrid, Barcelona, San Sebastián y Lleida. La investigación se fundamenta en la metodología Q, cuya combinación de elementos cuantitativos y cualitativos permite generar evidencias de modo sistemático, riguroso y cuantificable, sin renunciar a la complejidad y la riqueza del lenguaje de los propios actores. Los resultados nos revelan tres perspectivas sobre la participación (integral, regeneradora y desconfiada), divergentes en cuanto a su apreciación de las instituciones políticas y las organizaciones sociales. Con todo, también se constata la existencia de un núcleo de consenso sobre el que se pueden construir instituciones participativas más legítimas y eficaces.The article analyses and compares the thinking on citizen participation of elected and non-elected officials, as well as social activists of the Spanish cities of Madrid, Barcelona, San Sebastián and Lleida. The research is based on Q methodology, whose combination of quantitative and qualitative elements can generate systematic, rigorous and quantifiable evidence, without sacrificing the complexity and richness of language. The results reveal three distinct perspectives on participation (integral, regenerative and distrustful), that differ notably in their appreciation of political institutions and social organizations. However, results also point to the existence of a core of consensus beliefs, which opens the door to building more legitimate and effective participatory institutions