34 resultados para Stick-slip


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[cat] L’objectiu d’aquest breu article és provar i analitzar la influència de la saviesa d’Heràclit en alguns poemes de Miguel de Unamuno com ara ‘La elegía eterna’ i ‘La flor tronchada’. En certes ocasions –‘La elegía eterna’- Heràclit és per a ell una mena de crossa amb l’ajut de la qual reïx a mostrar poèticament les seves angoixes i, en d’altres –‘La flor tronchada’- necessita realment Heràclit per a il•lustrar la seva visió de Déu i de la vida humana com una lluita o guerra permanent.

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We investigate the depinning transition occurring in dislocation assemblies. In particular, we consider the cases of regularly spaced pileups and low-angle grain boundaries interacting with a disordered stress landscape provided by solute atoms, or by other immobile dislocations present in nonactive slip systems. Using linear elasticity, we compute the stress originated by small deformations of these assemblies and the corresponding energy cost in two and three dimensions. Contrary to the case of isolated dislocation lines, which are usually approximated as elastic strings with an effective line tension, the deformations of a dislocation assembly cannot be described by local elastic interactions with a constant tension or stiffness. A nonlocal elastic kernel results as a consequence of long-range interactions between dislocations. In light of this result, we revise statistical depinning theories of dislocation assemblies and compare the theoretical results with numerical simulations and experimental data.

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"static" instanton, representing pair creation of critical bubbles¿a process somewhat analogous to thermal activation in flat space. In that case, the branes may stick together due to thermal symmetry restoration, and the pair creation rate depends exponentially on the ambient de Sitter temperature, switching off sharply as the temperature approaches zero. Such a static instanton may be well suited for the ¿saltatory¿ relaxation scenario proposed by Feng et al.

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We study the forced displacement of a fluid-fluid interface in a three-dimensional channel formed by two parallel solid plates. Using a lattice-Boltzmann method, we study situations in which a slip velocity arises from diffusion effects near the contact line. The difference between the slip and channel velocities determines whether the interface advances as a meniscus or a thin film of fluid is left adhered to the plates. We find that this effect is controlled by the capillary and Péclet numbers. We estimate the crossover from a meniscus to a thin film and find good agreement with numerical results. The penetration regime is examined in the steady state. We find that the occupation fraction of the advancing finger relative to the channel thickness is controlled by the capillary number and the viscosity contrast between the fluids. For high viscosity contrast, lattice-Boltzmann results agree with previous results. For zero viscosity contrast, we observe remarkably narrow fingers. The shape of the finger is found to be universal.

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The Oligocene deposits of Montgat are integrated in a small outcrop made up of Cenozoic and Mesozoic rocks located in the Garraf-Montnegre horst, close to the major Barcelona fault. The Oligocene of Montgat consists of detrital sediments of continental origin mainly deposited in alluvial fan environments; these deposits are folded and affected by thrusts and strike-slip faults. They can be divided in two lithostratigraphic units separated by a minor southwest-directed thrust: (i) the Turó de Montgat Unit composed of litharenites and lithorudites with high contents of quartz, feldspar, plutonic and limestone rock fragments; and (ii) the Pla de la Concòrdia Unit composed of calcilitharenites and calcilithorudites with high contents of dolosparite and dolomicrite rock fragments. The petrological composition of both units indicates that sediments were derived from the erosion of Triassic (Buntsandstein, Muschelkalk and Keuper facies), Jurassic and Lower Cretaceous rocks (Barremian to Aptian in age). Stratigraphic and petrological data suggest that these units correspond to two coalescent alluvial fans with a source area located northwestwards in the adjoining Collserola and Montnegre inner areas. Micromammal fossils (Archaeomys sp.) found in a mudstone layer of the Pla de la Concòrdia Unit assign a Chattian age (Late Oligocene) to the studied materials. Thus, the Montgat deposits are the youngest dated deposits affected by the contractional deformation that led to the development of the Catalan Intraplate Chain. Taking into account that the oldest syn-rift deposits in the Catalan Coastal Ranges are Aquitanian in age, this allows to precise that the change from a compressive to an extensional regime in this area took place during latest Oligocene-earliest Aquitanian times. This age indicates that the onset of crustal extension related to the opening of the western Mediterranean Basin started in southern France during latest Eocene-early Oligocene and propagated southwestward, affecting the Catalan Coastal Ranges and the northeastern part of the Valencia trough during the latest Chattian-earliest Aquitanian times.

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The Oligocene deposits of Montgat are integrated in a small outcrop made up of Cenozoic and Mesozoic rocks located in the Garraf-Montnegre horst, close to the major Barcelona fault. The Oligocene of Montgat consists of detrital sediments of continental origin mainly deposited in alluvial fan environments; these deposits are folded and affected by thrusts and strike-slip faults. They can be divided in two lithostratigraphic units separated by a minor southwest-directed thrust: (i) the Turó de Montgat Unit composed of litharenites and lithorudites with high contents of quartz, feldspar, plutonic and limestone rock fragments; and (ii) the Pla de la Concòrdia Unit composed of calcilitharenites and calcilithorudites with high contents of dolosparite and dolomicrite rock fragments. The petrological composition of both units indicates that sediments were derived from the erosion of Triassic (Buntsandstein, Muschelkalk and Keuper facies), Jurassic and Lower Cretaceous rocks (Barremian to Aptian in age). Stratigraphic and petrological data suggest that these units correspond to two coalescent alluvial fans with a source area located northwestwards in the adjoining Collserola and Montnegre inner areas. Micromammal fossils (Archaeomys sp.) found in a mudstone layer of the Pla de la Concòrdia Unit assign a Chattian age (Late Oligocene) to the studied materials. Thus, the Montgat deposits are the youngest dated deposits affected by the contractional deformation that led to the development of the Catalan Intraplate Chain. Taking into account that the oldest syn-rift deposits in the Catalan Coastal Ranges are Aquitanian in age, this allows to precise that the change from a compressive to an extensional regime in this area took place during latest Oligocene-earliest Aquitanian times. This age indicates that the onset of crustal extension related to the opening of the western Mediterranean Basin started in southern France during latest Eocene-early Oligocene and propagated southwestward, affecting the Catalan Coastal Ranges and the northeastern part of the Valencia trough during the latest Chattian-earliest Aquitanian times.

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The aim of this brief article is to demonstrate and analyze the influence of Heraclitus’s thought on some of the poems written by Miguel de Unamuno, in particular ‘La elegía eterna’ and ‘La flor tronchada’. At times –as in ‘La elegía eterna’– Heraclitus merely serves as a sort of a walking stick, an aid to his efforts to poetically reveal his anxieties. On other occasions –as in ‘La flor tronchada’– he genuinely needs Heraclitus’s philosophy to illustrate his view of human life and its relation to God as unending warfare.

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La literatura ha estat, històricament, una forma de vivència i de coneixença del territori. En aquest sentit, el projecte Geografia literària dels Països Catalans esdevé una proposta de redescoberta de pobles, ciutats i comarques, de recuperació i fixació en la memòria d’espais, indrets, cases, monuments, edificis patrimonials o llocs mítics que han estat el centre d’interès dels nostres escriptors d’ençà dels trobadors i Ramon Llull fins als nostres dies. Per tot plegat, aquest treball té un triple objectiu: en primer lloc, donar a conèixer la iniciativa Geografia literària dels Països Catalans; en segon lloc, proposar-ne un marc teòric, i, per acabar, analitzar, específicament, alguns dels espais literaris que es localitzen a la comarca d’Osona.

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Since the begínning ofAdvertising, art has been a source ofinexhaustible inspiration for the advertising creative, who have used or misused it with any limits. With more or less direct references to artists, pieces or art movements, to references to the act ofart creation itself and certain aesthetic categories. Taking into account the various semantic versions that art offers, with multiple connotative lectures, this use has not been much profitable in many occasions, not as much as it could have been. However, in other circumstances, thís use has been vampirizing, only preoccupied for the audience impact ofa well knowll reference, but despising it and reducing it to a mere reclaim. In the case ofGiocconda by Leonardo da Vinci or the Birth ofVenus by Bottícelli are significant examples ofthis use, maybe popular, ofthe art productíon. That is to say that the depository was used as a source ofreferences to enrich the lectures ofthe advertising pieces (for instance, the excellent Citroen Xsara Picasso advertisement with the fordism mass production chain) or ¡ust to allow a higher t1Otoriety (like the Chupa-Chups advertisement where the Mona Lisa heartily sucks one ofthe mythical sweets with a stick). Thanks to a selected advertising pieces, graphical and audiovisual, we will be able to go through this kind ofadvertising creation logistics, from the moment that this one decided to call out these art references that were sleeping dreamingly Oll the fair in a depository until this strictly cultural moment came.

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The Quaternary Active Faults Database of Iberia (QAFI) is an initiative lead by the Institute of Geology and Mines of Spain (IGME) for building a public repository of scientific data regarding faults having documented activity during the last 2.59 Ma (Quaternary). QAFI also addresses a need to transfer geologic knowledge to practitioners of seismic hazard and risk in Iberia by identifying and characterizing seismogenic fault-sources. QAFI is populated by the information freely provided by more than 40 Earth science researchers, storing to date a total of 262 records. In this article we describe the development and evolution of the database, as well as its internal architecture. Aditionally, a first global analysis of the data is provided with a special focus on length and slip-rate fault parameters. Finally, the database completeness and the internal consistency of the data are discussed. Even though QAFI v.2.0 is the most current resource for calculating fault-related seismic hazard in Iberia, the database is still incomplete and requires further review.

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This work proposes the creation of a bioinspired electronic white cane for blind people using the whiskers principle for short-range navigation and exploration. Whiskers are coarse hairs of an animal's face that tells the animal that it has touched something using the nerves of the skin. In this work the raw data acquired from a low-size terrestrial LIDAR and a tri-axial accelerometer is converted into tactile information using several electromagnetic devices configured as a tactile belt. The LIDAR and the accelerometer are attached to the user’s forearm and connected with a wire to the control unit placed on the belt. Early validation experiments carried out in the laboratory are promising in terms of usability and description of the environment.

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The Bajo Segura fault zone (BSFZ) is the northern terminal splay of the Eastern Betic shear zone (EBSZ), a large left-lateral strike-slip fault system of sigmoid geometry stretching more than 450 km from Alicante to Almería. The BSFZ extends from the onshore Bajo Segura basin further into the Mediterranean Sea and shows a moderate instrumental seismic activity characterized by small earthquakes. Nevertheless, the zone was affected by large historical earthquakes of which the largest was the 1829 Torrevieja earthquake (IEMS98 X). The onshore area of the BSFZ is marked by active transpressive structures (faults and folds), whereas the offshore area has been scarcely explored from the tectonic point of view. During the EVENT-SHELF cruise, a total of 10 high-resolution single-channel seismic sparker profiles were obtained along and across the offshore Bajo Segura basin. Analysis of these profiles resulted in (a) the identification of 6 Quaternary seismo-stratigraphic units bounded by five horizons corresponding to regional erosional surfaces related to global sea level lowstands; and (b) the mapping of the active sub-seafloor structures and their correlation with those described onshore. Moreover, the results suggest that the Bajo Segura blind thrust fault or the Torrevieja left-lateral strike-slip fault, with prolongation offshore, could be considered as the source of the 1829 Torrevieja earthquake. These data improve our understanding of present deformation along the BSFZ and provide new insights into the seismic hazard in the area.

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Lignite deposits in the Cenozoic As Pontes strike-slip basin (northwestern Spain)were formed as a function of specific paleoclimatic conditions and tectonic evolution of the basin.

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Introducción: La incidencia de la presentación fetal podálica en España es del 3,8%. La moxibustión es parte integral de la milenaria medicina tradicional china. La técnica consiste en la colocación de un palillo incandescente de Artemisia vulgaris a unos pocos centímetros del punto de acupuntura Zhiyin (punto 67 del meridiano de vejiga, ubicado en la base externa de la uña del quinto dedo del pie). Los objetivos son: 1. Conocer el porcentaje de fetos que han rotado a cefálica mediante la moxibustión en gestantes que presenten una malposición fetal a partir de las 32 semanas de embarazo; 2. Identificar las complicaciones materno-fetales en la aplicación de la técnica. Sujetos: Se estudiaron 18 gestantes de más de 32 semanas de embarazo. Material y métodos: Mediante un estudio descriptivo de intervención, analizamos el porcentaje de fetos que rotaron a presentación cefálica. Resultados: Quince gestantes (83,9%) realizaron el tratamiento adecuadamente y las 3 restantes (16,7%) lo realizaron de manera ocasional y terminaron con una cesárea electiva por nalgas. Conclusiones: Parece razonable concluir que el cumplimiento del tratamiento influye en el tipo de parto (χ2= 12,600; gl= 1; p= 0,000), aunque no modifica el Apgar del recién nacido. Esta técnica se presenta como una alternativa económica, segura, sencilla y práctica para la versión fetal de la presentación podálica.

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Two small, alluvial-lacustrine subbasins developed during the early restraining overstep stages of the Oligocene-Miocene As Pontes strike-slip Basin (NW Spain). Later, the basin evolved into a restraining bend stage and an alluvial-swamp-dominated depositional framework developed. The palaeobiological record demonstrates that the Oligocene-Miocene palaeoclimate in NW Spain was subtropical, warm and humid to subhumid.