Juan Fernández

Cefalea cardíaca: ¿una entidad infradiagnosticada?

La cefalea cardiaca, o cefalea como manifestacion de isquemia miocardica, es una entidad individualizada recientemente. Su diagnostico en un paciente con cardiopatia isquemica requiere una cefalea intensa, acompanada de nauseas y empeorada por el ejercicio, que cede tras la administracion de nitratos. Presentamos los casos de 2 pacientes que cumplian estos criterios diagnosticos. En ambos, esta cefalea fue el unico sintoma de isquemia coronaria, lo que retraso el diagnostico, acontecio con esfuerzos y en reposo, y solo cedio tras la administracion de nitratos. La cefalea cardiaca ha de sospecharse en pacientes con cardiopatia isquemica que consultan por cefalea de reciente comienzo, aunque no presenten dolor toracico, sobre todo si mejoran con nitratos. El diagnostico diferencial con la migrana es crucial de cara a evitar medicaciones vasoconstrictoras.

Stencil computations on heterogeneous platforms for the Jacobi method: GPUs versus Cell BE

We are witnessing the consolidation of the heterogeneous computing in parallel computing with architectures such as Cell Broadband Engine (Cell BE) or Graphics Processing Units (GPUs) which are present in a myriad of developments for high performance computing. These platforms provide a Software Development Kit (SDK) to maximize performance at the expense of dealing with complex and low-level architectural details which makes the software development a daunting task. This paper explores stencil computations in several heterogeneous programming models like Cell SDK, CellSs, ALF and CUDA to optimize the Jacobi method for solving Laplace’s differential equation. We describe the programming techniques to extract the maximum performance on the Cell BE and the GPU, and compare their computing paradigms. Experimental results are shown on two Nvidia Teslas and one IBM BladeCenter QS20 blade which incorporates two 3.2xa0GHz Cell BEs vxa05.1. The speed-up factor for our set of GPU optimizations reaches 3–4×, and the execution times defeat those of the Cell BE by an order of magnitude, also showing great scalability when moving towards newer GPU generations and/or more demanding problem sizes.

Design of an efficient communication infrastructure for highly contended locks in many-core CMPs

Lock synchronization is a key programming primitive for shared-memory many-core CMPs. However, as the number of cores increases, conventional software implementations cannot meet the desirable levels of performance and scalability. Meanwhile, most existing hardware-supported lock proposals require modifications at some level of the memory hierarchy, thus degrading QoS of applications through synchronization traffic. n nIn this paper, we propose GLock, a dedicated network infrastructure and a token-based message-passing protocol to provide a non-intrusive, extremely efficient and fair implementation for highly contended locks. Two implementations of GLock are considered. The first leverages current full-custom G-lines technology, whilst the second uses a cost-effective mainstream industrial toolflow with an advanced 45 nm technology. When compared with the most efficient software-based lock, both alternatives provide significant reductions in execution time, network traffic and power consumption, for a representative set of benchmarks, with negligible area overhead.

Cardiac Cephalgia: an Underdiagnosed Condition?

Cardiac cephalgia, or headache occurring as manifestation of myocardial ischemia, has only recently been recognized as a distinct entity. In patients with known ischemic cardiopathy, its diagnosis depends on the presence of severe headache that is accompanied by nausea, worsened by physical exercise, and only ceases with nitrate administration. We report on two patients who met diagnostic criteria for this entity. In both, headache was the only symptom of coronary ischemia, and delayed its diagnosis. Headache occurred both at rest and during exertion, and resolved only after the administration of nitrates. Cardiac cephalgia should be suspected in patients with a history of ischemic cardiopathy who present with de novo headache, even when thoracic pain is absent, especially if the headache improves with nitrates. Differential diagnosis with migraine is crucial to avoid the administration of vasoconstrictors.

Suspended sediment observations in the Barcelona inner-shelf during storms

ABSTRACT Grifoll, M., Gracia, V., Fernandez, J. and Espino, M. 2013. Suspended sediment observations in the Barcelona inner-shelf during storms. This contribution describes in detail the Suspended Sediment Concentration (SSC) obtained from an observational set at 24 m depth in the Catalan inner-shelf (North-western Mediterranean Sea) analysing the dominant processes affecting sediment dynamics during storm events. A clear correlation between SSC, energetic waves, and along-shelf currents events has been found. Peaks in river discharge associated to rainy events are also correlated with SSC measurements. Measured conditions highlight the different sediment dynamic situations present during short-term events such as “wet” and “dry” storms with similar wave height. SSC observed during “dry” conditions are correlated with wave action. On the other hand, SSC peaks during “wet” conditions are primarily caused by wave action, along-shelf current, and river discharge. Observed sediment fluxes during storms are larger in spring than during fall. Although the observations present similar characteristics to other inner-shelf regions in the NW Mediterranean Sea, the results reveal a non-negligible influence of the along-shelf current in sediment dynamics. The results presented here contribute to advance in the understanding of sediment dynamics in wave-dominated regions such as the Catalan shelf.

Capability Assessment of Sediment Transport Forecasting in Mediterranean Continental Shelves

Comunicacion presentada en Coastal Sediments 2011, celebrado del 2 al 6 de mayo de 2011 en Miami, Florida (Estados Unidos)