Role of Particle Shape on the Stress Propagation in Granular Packings

We present an experimental and numerical study on the influence that particle aspect ratio has on the mechanical and structural properties of granular packings. For grains with maximal symmetry (squares), the stress propagation in the packing localizes forming chainlike forces analogous to the ones observed for spherical grains. This scenario can be understood in terms of stochastic models of aggregation and random multiplicative processes. As the grains elongate, the stress propagation is strongly affected. The interparticle normal force distribution tends toward a Gaussian, and, correspondingly, the force chains spread leading to a more uniform stress distribution reminiscent of the hydrostatic profiles known for standard liquids

Servidor municipal de datos espaciales con capacidad para WMTS : aplicación al callejero municipal de Malgrat de Mar

El sistema inclou un servidor d'aplicacions, un servidor de dades espacials i un sistema gestor de bases de dades alfanumèriques; dóna servei de mapes sota l'especificació Web Map Tile Service, de l'OGC, i s'explica el procés de confecció dels tiles per a cada nivell de zoom amb el programari GeoWebCache integrat en Geoserver. Mostra l'estructura de matrius de tessel·les (TileMatrix) i piràmides (TileMatrixSets). Implementa un portal visualitzador de mapes (geoportal), capaç per a WMTS i WMS, amb les opcions d'exploració de capes i consulta a la base de dades del carrerer oficial de l'Ajuntament de Malgrat de Mar

Improved earthquake response via simulation and integrated space- and ground-based technologies: the TREMOR proposal

Earthquakes occurring around the world each year cause thousands ofdeaths, millions of dollars in damage to infrastructure, and incalculablehuman suffering. In recent years, satellite technology has been asignificant boon to response efforts following an earthquake and itsafter-effects by providing mobile communications between response teamsand remote sensing of damaged areas to disaster management organizations.In 2007, an international team of students and professionals assembledduring theInternational Space University’s Summer Session Program in Beijing, Chinato examine how satellite and ground-based technology could be betterintegrated to provide an optimised response in the event of an earthquake.The resulting Technology Resources for Earthquake MOnitoring and Response(TREMOR) proposal describes an integrative prototype response system thatwill implement mobile satellite communication hubs providing telephone anddata links between response teams, onsite telemedicine consultation foremergency first-responders, and satellite navigation systems that willlocate and track emergency vehicles and guide search-and-rescue crews. Aprototype earthquake simulation system is also proposed, integratinghistorical data, earthquake precursor data, and local geomatics andinfrastructure information to predict the damage that could occur in theevent of an earthquake. The backbone of these proposals is a comprehensiveeducation and training program to help individuals, communities andgovernments prepare in advance. The TREMOR team recommends thecoordination of these efforts through a centralised, non-governmentalorganization.

Patient-specific computational hemodynamics of intracranial aneurysms from 3D rotational angiography and CT angiography: an in vivo reproducibility study

Patient-specific simulations of the hemodynamics in intracranial aneurysms can be constructed by using image-based vascular models and CFD techniques. This work evaluates the impact of the choice of imaging technique on these simulations

How do coil configuration and packing density influence intra-aneurysmal hemodynamics?

Endovascular coiling is a well-established therapy for treating intracranial aneurysms. Nonetheless, postoperative hemodynamic changes induced by this therapy remain not fully understood. The purpose of this work is to assess the influence of coil configuration and packing density on intra-aneurysmal hemodynamics

Toward integrated management of cerebral aneurysms

In the last few years, some of the visionary concepts behind the virtual physiological human began to be demonstrated on various clinical domains, showing great promise for improving healthcare management. In the current work, we provide an overview of image- and biomechanics-based techniques that, when put together, provide a patient-specific pipeline for the management of intracranial aneurysms. The derivation and subsequent integration of morphological, morphodynamic, haemodynamic and structural analyses allow us to extract patient-specific models and information from which diagnostic and prognostic descriptors can be obtained. Linking such new indices with relevant clinical events should bring new insights into the processes behind aneurysm genesis, growth and rupture. The development of techniques for modelling endovascular devices such as stents and coils allows the evaluation of alternative treatment scenarios before the intervention takes place and could also contribute to the understanding and improved design of more effective devices. A key element to facilitate the clinical take-up of all these developments is their comprehensive validation. Although a number of previously published results have shown the accuracy and robustness of individual components, further efforts should be directed to demonstrate the diagnostic and prognostic efficacy of these advanced tools through large-scale clinical trials.

Deployment of self-expandable stents in aneurysmatic cerebral vessels: comparison of different computational approaches for interventional planning

In the last few years, there has been a growing focus on faster computational methods to support clinicians in planning stenting procedures. This study investigates the possibility of introducing computational approximations in modelling stent deployment in aneurysmatic cerebral vessels to achieve simulations compatible with the constraints of real clinical workflows. The release of a self-expandable stent in a simplified aneurysmatic vessel was modelled in four different initial positions. Six progressively simplified modelling approaches (based on Finite Element method and Fast Virtual Stenting – FVS) have been used. Comparing accuracy of the results, the final configuration of the stent is more affected by neglecting mechanical properties of materials (FVS) than by adopting 1D instead of 3D stent models. Nevertheless, the differencesshowed are acceptable compared to those achieved by considering different stent initial positions. Regarding computationalcosts, simulations involving 1D stent features are the only ones feasible in clinical context.

Three-dimensional morphological analysis of intracranial aneurysms: a fully automated method for aneurysm sac isolation and quantification

Morphological descriptors are practical and essential biomarkers for diagnosis andtreatment selection for intracranial aneurysm management according to the current guidelinesin use. Nevertheless, relatively little work has been dedicated to improve the three-dimensionalquanti cation of aneurysmal morphology, automate the analysis, and hence reduce the inherentintra- and inter-observer variability of manual analysis. In this paper we propose a methodologyfor the automated isolation and morphological quanti cation of saccular intracranial aneurysmsbased on a 3D representation of the vascular anatomy.

On codes, matroids, and secure multiparty computation from linear secret-sharing schemes

Error-correcting codes and matroids have been widely used in the study of ordinary secret sharing schemes. In this paper, the connections between codes, matroids, and a special class of secret sharing schemes, namely, multiplicative linear secret sharing schemes (LSSSs), are studied. Such schemes are known to enable multiparty computation protocols secure against general (nonthreshold) adversaries.Two open problems related to the complexity of multiplicative LSSSs are considered in this paper. The first one deals with strongly multiplicative LSSSs. As opposed to the case of multiplicative LSSSs, it is not known whether there is an efficient method to transform an LSSS into a strongly multiplicative LSSS for the same access structure with a polynomial increase of the complexity. A property of strongly multiplicative LSSSs that could be useful in solving this problem is proved. Namely, using a suitable generalization of the well-known Berlekamp–Welch decoder, it is shown that all strongly multiplicative LSSSs enable efficient reconstruction of a shared secret in the presence of malicious faults. The second one is to characterize the access structures of ideal multiplicative LSSSs. Specifically, the considered open problem is to determine whether all self-dual vector space access structures are in this situation. By the aforementioned connection, this in fact constitutes an open problem about matroid theory, since it can be restated in terms of representability of identically self-dual matroids by self-dual codes. A new concept is introduced, the flat-partition, that provides a useful classification of identically self-dual matroids. Uniform identically self-dual matroids, which are known to be representable by self-dual codes, form one of the classes. It is proved that this property also holds for the family of matroids that, in a natural way, is the next class in the above classification: the identically self-dual bipartite matroids.

Women of the beat generation : la traducción de una obra poética coral

Comentario a la traducción por encargo del libro WOTBG, centrado en las muestras de obra poética de las distintas autoras y la necesidad de conservar sus similitudes y sus diferéncias.

Rep Sol el Morell?

L’objecte del treball és analitzar com afecta la instal·lació d’una gran empresa en un poble relativament petit, més concretament com va afectar la implantació d’unarefineria al 1975, que ara pertany a Repsol YPF, a la vida del Morell (Tarragonès).Per veure les diferències més clarament s’ha decidit fer una comparació amb un altrepoble similar, Vilallonga del Camp, que fa frontera amb el Morell. L’elecció d’aquestpoble és un dels passos més importants del treball.L’objectiu d’aquest treball és analitzar l’evolució d’un poble del Tarragonès, el Morell,després de la instal·lació d’una refineria de la Respol. Com que la implantació va ser famés de trenta anys, hem considerat convenient avaluar les diferències i similituds ambels canvis d’un altre poble. Creiem que aquesta elecció és un pas fonamental del treball,i per això, ha estat, probablement, la part més difícil.Hem pensat en molts candidats, per exemple La Pobla de Montornès, Salomó, laSecuita (Tarragonès), Riudoms (Baix Camp), etc.Però finalment ens vam decantar per Vilallonga del Camp, també situat al Tarragonès;ja que reuneix les condicions necessàries per realitzar l’anàlisi que volíem fer. Si bé notenia ni la mateixa extensió ni el mateix nombre d’habitants quan es va implantar larefineria (uns dels objectius desitjats a l’hora d’escollir el poble a comparar), sí quecompleix el requisit que la indústria estava localitzada només en el terme municipal delMorell i no de Vilallonga del Camp. Addicionalment, hem considerat que les similitudsamb el Morell eren més importants que aquestes discrepàncies. És a dir, ambdós pobleses dedicaven al mateix sector productiu en el moment de la implantació de la indústria,l’agricultura, a més, els nuclis urbans estan separats per només un quilòmetre, això voldir que la climatologia és la mateixa i que les diferències de comunicacions no són gaireimportants; per tant partien d’una situació similar i amb les mateixes expectatives defutur. A partir d’aquí preteníem estudiar l’evolució dels dos pobles, i com tots aquestsfactors han anat variant al llarg del temps.

Proyecto Kimbi : Márketing viral. Pásalo o no

“Un reciente estudio de la consultora Nielsen estima en 49.650 millones de € las pérdidas anuales procedentes de la inversión en publicidad no efectiva en el mundo”.Esta noticia refleja un hecho que causa alarmismo en la sociedad. Semejante gasto desbaratado en llevar a cabo un proyecto que no causa ningún beneficio es motivo de preocupación entre economistas y profesionales del Marketing. Ciertamente, entenderíamos que multitud de personas se llevasen las manos a la cabeza ante la evidencia de semejante despilfarro. Llegados a este punto, hay que comunicar dos hechos. En primer lugar, hemos de aclarar que este es un titular ficticio y los datos que se aportan son irreales.Lamentablemente, en segundo lugar se ha de exponer que las cifras estimadas reales duplican –siendo optimistas‐ las anteriormente citadas (1 “Advertising expenditure forecast 2008” ZenithOptimedia – Nielsen Facts 2008).Actualmente los expertos en Marketing están en medio de un proceso de búsqueda de nuevas fórmulas que aumenten la eficacia y reduzcan el gasto de sus campañas publicitarias, y ése es el terreno en donde se mueve el Marketing viral, fenómeno en plena expansión gracias a la creciente importancia de Internet en nuestras vidas.Este hecho fue lo que nos ha empujado a investigar sobre la disciplina y sus métodos.Descubrir qué se ocultaba detrás de la categoría “viral” y darnos cuenta de su imparable desarrollo, descubriendo cómo habíamos sido a la vez verdugos y mártires en la propagación de mensajes publicitarios.En nuestro trabajo queremos darle un nuevo sentido al concepto de ahorro en el Marketing viral, intentado descubrir si es posible llevar a cabo una transformación low‐cost del concepto de Marketing viral y aplicarla con éxito a un sector de lapoblación en el que podamos controlar los efectos de una campaña de dichas características, por lo cual escogimos a los estudiantes del campus de Ciutadella de la Universidad Pompeu Fabra como target de nuestra campaña.Además, nos planteamos analizar el ahorro de nuestra campaña mediante el análisis y comparación coste‐resultado de otras vías de Marketing tradicionales con un concepto novedoso y a la vez preciso como es el de “eficacia real publicitaria”, en el cual nos servimos de estudios sociopsicológicos de consumidores para establecer unosbaremos más cercanos a la realidad que los métodos más comunes de medición de resultados publicitarios.Para ello, es necesario crear una identidad completamente nueva. Es aquí donde surge la marca, franquicia, empresa, organización y filosofía –ficticias‐ Kimbi. Y el reto exige un esfuerzo notable: dar a conocer una identidad –comercial y empresarial‐ ficticia que no ofrece ningún servicio ni producto a un sector poblacional y crear expectativas en elobjetivo, llamar su atención, grabar en sus mentes nuestros identificativos y esperar que el virus del “movimiento Kimbi” se propague entre ellos con éxito. Es decir, competir en el saturado panorama publicitario contra multitud de multinacionales que ya tienen unos usuarios fieles y una reputación labrada, que ofrecen productos y servicios de manera gratuita en bastantes ocasiones y que disponen de ingentes cantidades de recursos y capital para publicitar su identidad comercial en multitud de medios mainstream con el objetivo de atraerles y causarles un impacto publicitario. Esperamos haber conseguido, al menos, que el lector sienta el deseo de ver el trabajo. ¿Queréis descubrir el resultado?

Daño neurológico detectado por RM difusión y variaciones en el estado neurocognitivo tras implante de TAVI vs. RVA en pacientes con similar perfil de riesgo:) Datos preliminares

El presente trabajo muestra los datos preliminares de una estudio de cohortes prospectivo unicéntrico que pretende comparar el daño neurológico asociado a dos intervenciones cardiacas para el tratamiento de la estenosis aórtica severa. Concretamente se analiza la aparición de lesiones isquémica agudas cerebrales detectadas por RM tras los dos procedimientos y su posible asociación con alteraciones del estado neurocognitivo en la evolución. La presentación actual solo muestra los datos preliminares de los resultados de la RM cerebral. En el apartado métodos se describe también como se realizó la valoración del estado neurocognitivo, no obstante, los resultados de estas valoraciones y su posible correlación con las lesiones en la RM cerebral aún no estan analizados y por lo tanto no se presentan.

Correlació entre resposta radiològica i resposta patològica en pacients amb càncer de mama tractades amb quimioteràpia neoadjuvant.

En pacients amb càncer de mama la ressonància magnètica és superior a altres exploracions per a monitoritzar la resposta a la quimioteràpia neoadjuvant. Analitzem la correlació entre resposta completa radiològica(RCr) valorada amb RM i resposta completa patològica (RCp), globalment i en funció dels diferents immunofenotips. Es tracta d´un estudi clínic, retrospectiu, on s´han inclòs 103 pacients tractades amb quimioteràpia neoadjuvant. Totes les pacients incloses disposaven de RM inicial i de RM post-quimioteràpia. La sensibilitat de la RM per a detectar RCp és d´un 82% i l´especificitat d´un 71%. El valor de sensibilitat més alt, del 100%, s´ha objectivat en els tumors triple negatius. La concordança global entre RCr i RCp és d´un 74%.

The effects of employment uncertainty and wealth shocks on the labor supply and claiming behavior of older American workers

Unemployment rates in developed countries have recently reached levels not seenin a generation, and workers of all ages are facing increasing probabilities of losingtheir jobs and considerable losses in accumulated assets. These events likely increasethe reliance that most older workers will have on public social insurance programs,exactly at a time that public finances are suffering from a large drop in contributions.Our paper explicitly accounts for employment uncertainty and unexpectedwealth shocks, something that has been relatively overlooked in the literature, butthat has grown in importance in recent years. Using administrative and householdlevel data we empirically characterize a life-cycle model of retirement and claimingdecisions in terms of the employment, wage, health, and mortality uncertainty facedby individuals. Our benchmark model explains with great accuracy the strikinglyhigh proportion of individuals who claim benefits exactly at the Early RetirementAge, while still explaining the increased claiming hazard at the Normal RetirementAge. We also discuss some policy experiments and their interplay with employmentuncertainty. Additionally, we analyze the effects of negative wealth shocks on thelabor supply and claiming decisions of older Americans. Our results can explainwhy early claiming has remained very high in the last years even as the early retirementpenalties have increased substantially compared with previous periods, andwhy labor force participation has remained quite high for older workers even in themidst of the worse employment crisis in decades.