Reconstructing snow avalanches in the Southeastern Pyrenees

A regional study of snow avalanche processes was undertaken in the SE Pyrenees. Dendrogeomorphology was used to date and reconstruct large-scale snow avalanche events that occurred in the last four decades. Dendrochronological analyses yielded the dates of nine winters when avalanches occurred in the recent past in six studied avalanche paths. Some of these avalanches were already known, but others had not been documented. In one case, the existing avalanche path map was improved with the dendrogeomorphological information of a larger past event. As a result of the dendrogeomorphological analyses, evidence for three regional-scale major avalanche years was identified in the SE Pyrenees from 1971 to 2004: 1971¿1972, 1995¿1996 and 2002¿2003. The specific synoptic atmospheric situations and the most likely nivometeorological and snowpack conditions that released these major avalanches were determined using weather data for the seasons of major avalanche releases. In 1971¿1972 the snow avalanche episode was characterized by a deep trough crossing the Pyrenees. In 1995¿1996 a variety of meteorological situations produced several episodes of major avalanches. In 2002¿2003 the more significant of two episodes was attributed to a north advection pumping an arctic air mass over the Pyrenees. The 1995¿1996 avalanche season proved to be the most notable in the four past decades in the Pyrenees.

L'educació a Catalunya

Cercar antecedents historics de la situació política actual a Catalunya equival a aprofundir en els orígens de la nostra constitució com a poble. I en aquest sentit cal destacar que 1989 ha estat considerat -si bé amb certes polemiques- l'any de I'acompliment del primer milalenari. Deixarem ara de banda altres consideracions i les pinzellades historiques que segueixen es limitaran a l'ambit educatiu. Com és ben sabut, el Decret de Nova Planta, que va dictar Felip V el 1714, després de la presa de Barcelona, va abolir totes les institucions catalanes d'autogovern i va iniciar un llarg període de repressió lingüística i cultural que, tanmateix, no va ser obstacle perque en ple segle XVIII sorgissin obres pedagogiques com Instruccions per a l'ensenyanga de minyons de Baldiri Reixac.

Mobile robot experimental modeling and control strategies using sensor fusion

This research work deals with the problem of modeling and design of low level speed controller for the mobile robot PRIM. The main objective is to develop an effective educational, and research tool. On one hand, the interests in using the open mobile platform PRIM consist in integrating several highly related subjects to the automatic control theory in an educational context, by embracing the subjects of communications, signal processing, sensor fusion and hardware design, amongst others. On the other hand, the idea is to implement useful navigation strategies such that the robot can be served as a mobile multimedia information point. It is in this context, when navigation strategies are oriented to goal achievement, that a local model predictive control is attained. Hence, such studies are presented as a very interesting control strategy in order to develop the future capabilities of the system. In this context the research developed includes the visual information as a meaningful source that allows detecting the obstacle position coordinates as well as planning the free obstacle trajectory that should be reached by the robot

Les Galeries Dalmau: un projecte de modernitat a la ciutat de Barcelona

Principis del segle XX, la burgesia, conscient del seu estatus, va conduir la cultura catalana cap a una modernitat de caire neoclassicista i d’orígens mediterranis: el Noucentisme. Aquest moviment va ser un obstacle clar per a l’Avantguarda, que no només implicava la negació de l’art passat, sinó també el refús de la imatge realista del món, així com una voluntat d’experimentació formal. Malgrat que l’ambient no era propici per al desenvolupament lliure d’aquest art modern, el galerista Josep Dalmau i Rafel (1867-1937), atent als canvis de la seva època, va aventurar-se a traslladar, per primera vegada, els “ismes” europeus del començament de segle a la ciutat comtal. L’Exposició d’Art Cubista, que es va celebrar entre el 20 d’abril i el 10 de maig de 1912 a les seves Galeries, va ser la mostra inicial més important de l’art d’Avantguarda a Catalunya.

Percolation and three-dimensional structure of supercritical water

It is well established that at ambient and supercooled conditions water can be described as a percolating network of H bonds. This work is aimed at identifying, by neutron diffraction experiments combined with computer simulations, a percolation line in supercritical water, where the extension of the H-bond network is in question. It is found that in real supercritical water liquidlike states are observed at or above the percolation threshold, while below this threshold gaslike water forms small, sheetlike configurations. Inspection of the three-dimensional arrangement of water molecules suggests that crossing of this percolation line is accompa- nied by a change of symmetry in the first neighboring shell of molecules from trigonal below the line to tetrahedral above.

Modeling and control of electromechanical systems

The material presented in the these notes covers the sessions Modelling of electromechanical systems, Passive control theory I and Passive control theory II of the II EURON/GEOPLEX Summer School on Modelling and Control of Complex Dynamical Systems.We start with a general description of what an electromechanical system is from a network modelling point of view. Next, a general formulation in terms of PHDS is introduced, and some of the previous electromechanical systems are rewritten in this formalism. Power converters, which are variable structure systems (VSS), can also be given a PHDS form.We conclude the modelling part of these lectures with a rather complex example, showing the interconnection of subsystems from several domains, namely an arrangement to temporally store the surplus energy in a section of a metropolitan transportation system based on dc motor vehicles, using either arrays of supercapacitors or an electric poweredflywheel. The second part of the lectures addresses control of PHD systems. We first present the idea of control as power connection of a plant and a controller. Next we discuss how to circumvent this obstacle and present the basic ideas of Interconnection and Damping Assignment (IDA) passivity-based control of PHD systems.

First-passage and escape problems in the Feller process

The Feller process is an one-dimensional diffusion process with linear drift and state-dependent diffusion coefficient vanishing at the origin. The process is positive definite and it is this property along with its linear character that have made Feller process a convenient candidate for the modeling of a number of phenomena ranging from single-neuron firing to volatility of financial assets. While general properties of the process have long been well known, less known are properties related to level crossing such as the first-passage and the escape problems. In this work we thoroughly address these questions.

Electrical signature of modern and ancient tectonic processes in the crust of the Atlas mountains of Morocco.

The Atlas Mountains in Morocco are considered as type examples of intracontinental chains, with high topography that contrasts with moderate crustal shortening and thickening. Whereas recent geological studies and geodynamic modeling have suggested the existence of dynamic topography to explain this apparent contradiction, there is a lack of modern geophysical data at the crustal scale to corroborate this hypothesis. Newly-acquired magnetotelluric data image the electrical resistivity distribution of the crust from the Middle Atlas to the Anti-Atlas, crossing the tabular Moulouya Plain and the High Atlas. All the units show different and unique electrical signatures throughout the crust reflecting the tectonic history of development of each one. In the upper crust electrical resistivity values may be associated to sediment sequences in the Moulouya and Anti-Atlas and to crustal scale fault systems in the High Atlas developed during the Cenozoic times. In the lower crust the low resistivity anomaly found below the Mouluya plain, together with other geophysical (low velocity anomaly, lack of earthquakes and minimum Bouguer anomaly) and geochemical (Neogene-Quaternary intraplate alkaline volcanic fields) evidence, infer the existence of a small degree of partial melt at the base of the lower crust. The low resistivity anomaly found below the Anti-Atlas may be associated with a relict subduction of Precambrian oceanic sediments, or to precipitated minerals during the release of fluids from the mantle during the accretion of the Anti-Atlas to the West African Supercontinent during the Panafrican orogeny ca. 685 Ma).

Arte publico 2010

El concepto de arte público es un término polisémico cuyos significados se reflejan en la diversidad de recursos que podemos hallar en internet. Por lo tanto, la aproximación a dichos recursos requerirá una acotación del propio concepto, que transita entre los ámbitos de la escultura, el monumento, las artes visuales y el espacio urbano entendido desde su vertiente cívica. La aproximación a los contenidos de internet vinculados con el arte público se aborda desde tres áreas temáticas cuyo análisis nos ayudará a organizar un volumen heterogéneo de información. La primera área incide en el papel de los centros de investigación y ayuntamientos en la promoción, inventariado y catalogación de las colecciones de arte en el espacio público. La segunda se centra en aquellos sitios web que son entendidos como fuentes de información y herramientas; los denominados think tanks. La tercera y última destaca la presencia en la red de páginas oficiales dedicadas a autores y obras específicas. The concept of public art is a polysemic term, and the dispersion of its meaning is reflected in the diversity of resources we can find on the web. Therefore, the approach to these resources needs a delimitation of the concept, crossing the fields of Sculpture, Monument, Visual arts and Urban space, defined from a civic perspective. The management of these resources is addressed from three strands, whose analysis will help us to organize a heterogeneous volume of information. The first affects the role of research centers and municipalities in the promotion, inventory and cataloging of collections of art in public spaces. The second focuses on those websites understood as sources of information and resources, the so-called think tanks. The third highlights the presence in the web of official sites devoted to specific authors and works. Keywords: public art, monument, public space, internet

JXTA-Overlay P2P Platform and Its Application for Robot Control

The design of an efficient collaborative multirobot framework that ensures the autonomy and the individualrequirements of the involved robots is a very challenging task. This requires designing an efficient platform for inter-robot communication. P2P is a good approach to achieve this goal. P2P aims at making the communication ubiquitous thereby crossing the communication boundary and has many attractive features to use it as a platform for collaborative multi-robot environments. In this work, we present the JXTA Overlay P2P system and its application for robot control. Since JXTAOverlay is able to overcome Firewalls, Routers and NATs, it is possible to control end-devices in a WAN without changing the network security policy. We used JXTA-Overlay for the control of robot motors. We evaluated the proposed system by many experiments and have shown that the proposed system has a good performance and can be used successfully for the control of robot.

Diagnosi d'una llei franquista: la Llei de Redempció de Censos de 1945

El 31 de desembre de 1945 les cons franquistes van aprovar una Llei de Redempció de Censos específica per a Catalunya. Es tractava d'una llei que permetia als censataris, és a dir, als emfiteutes, als propietaris de finques gravades amb censos, d'accedir a la propietat plena de les "seves" finques, és a dir, de les finques de les quals eren titulars del domini útil. D'entrada, la promulgació d'una llei com aquesta, en el marc d'un règim franquista, pot provocar un cert desconcert. En el discurs historiogràfic dominant sobre l'Espanya contemporània, la supervivència dels censos ha estat vista com una prova de la supervivència dels drets feudals, és a dir, com una clara rèmora del passat, com una evidencia del caràcter incomplet de la revolució liberal, i també com un obstacle al desenvolupament agrari i, per tant, al creixement econòmic'. Una llei de redempció de censos ha tendit a ser vista, en aquest context, com una llei clarament beneficiosa per al conjunt de la societat i, en particular, per a la pagesia i els sectors més populars. El corol·lari que es deriva d’aquesta percepció implica, admetem-ho, una visió favorable al paper del franquisme: aquest regim hauria exercit, en aquest terreny específic de les relacions socials agràries, un paper modernitzadori, i també, un paper clarament favorable a les classes populars

The global carbon budget:a conflicting claims problem

Despite global environmental governance has traditionally couched global warming in terms of annual CO2 emissions (a flow), global mean temperature is actually determined by cumulative CO2 emissions in the atmosphere (a stock). Thanks to advances of scientific community, nowadays it is possible to quantify the \global carbon budget", that is, the amount of available cumulative CO2 emissions before crossing the 2oC threshold (Meinshausen et al., 2009). The current approach proposes to analyze the allocation of such global carbon budget among countries as a classical conflicting claims problem (O'Neill, 1982). Based on some appealing principles, it is proposed an efficient and sustainable allocation of the available carbon budget from 2000 to 2050 taking into account different environmental risk scenarios. Keywords: Carbon budget, Conflicting claims problem, Distribution, Climate change. JEL classification: C79, D71, D74, H41, H87, Q50, Q54, Q58.

Micromorphological characterization and lithification of microbial mats from the Ebro Delta (Spain)

The structural organization of microbial mats from the Ebro Delta (Spain) and their accretion and partial lithification processes were explored using scanning electron microscopy in back-scattered electron mode and low-temperature scanning electron microscopy. Two differentiated zones were distinguished in a transverse section of a fragment taken from the mat at a depth of 2.5 mm. The first consisted of an upper layer in which the dominant microorganisms, Microcoleus spp., actively grew in an embedded slack matrix of exopolysaccharides. Microcoleus filaments were oriented parallel to the surface and to each other, with filaments below arranged perpendicularly to one another but without crossing. Most of the minerals present were allochthonous grains of calcium phosphate biocorroded by cyanobacteria. The second zone was below a depth of 1 mm and made up of accretion layers with large deposits of calcium carbonate and smaller amounts of calcium phosphate of biological origin. The predominance of a particular type of mineral precipitation with a characteristic external shape and/or texture within a zone, e.g., sponge-like deposits of calcium phosphate, appears to depend on the taxa of the prevailing microorganisms

Electrical signature of modern and ancient tectonic processes in the crust of the Atlas mountains of Morocco.

The Atlas Mountains in Morocco are considered as type examples of intracontinental chains, with high topography that contrasts with moderate crustal shortening and thickening. Whereas recent geological studies and geodynamic modeling have suggested the existence of dynamic topography to explain this apparent contradiction, there is a lack of modern geophysical data at the crustal scale to corroborate this hypothesis. Newly-acquired magnetotelluric data image the electrical resistivity distribution of the crust from the Middle Atlas to the Anti-Atlas, crossing the tabular Moulouya Plain and the High Atlas. All the units show different and unique electrical signatures throughout the crust reflecting the tectonic history of development of each one. In the upper crust electrical resistivity values may be associated to sediment sequences in the Moulouya and Anti-Atlas and to crustal scale fault systems in the High Atlas developed during the Cenozoic times. In the lower crust the low resistivity anomaly found below the Mouluya plain, together with other geophysical (low velocity anomaly, lack of earthquakes and minimum Bouguer anomaly) and geochemical (Neogene-Quaternary intraplate alkaline volcanic fields) evidence, infer the existence of a small degree of partial melt at the base of the lower crust. The low resistivity anomaly found below the Anti-Atlas may be associated with a relict subduction of Precambrian oceanic sediments, or to precipitated minerals during the release of fluids from the mantle during the accretion of the Anti-Atlas to the West African Supercontinent during the Panafrican orogeny ca. 685 Ma).

All-sky search algorithms for monochromatic signals in bar gravitational wave detector data

In this paper we design and develop several filtering strategies for the analysis of data generated by a resonant bar gravitational wave (GW) antenna, with the goal of assessing the presence (or absence) therein of long-duration monochromatic GW signals, as well as the eventual amplitude and frequency of the signals, within the sensitivity band of the detector. Such signals are most likely generated in the fast rotation of slightly asymmetric spinning stars. We develop practical procedures, together with a study of their statistical properties, which will provide us with useful information on the performance of each technique. The selection of candidate events will then be established according to threshold-crossing probabilities, based on the Neyman-Pearson criterion. In particular, it will be shown that our approach, based on phase estimation, presents a better signal-to-noise ratio than does pure spectral analysis, the most common approach.