Inelastic torsional seismic response of nominally symmetric reinforced concrete frame structures: shaking table tests

This paper discusses the torsional response of a scaled reinforced concrete frame structure subjected to several uniaxial shaking table tests. The tested structure is nominally symmetric in the direction of shaking and exhibits torsion attributable to non-uniform yielding of structural components and uncertainties in the building process. Asymmetric behavior is analyzed in terms of displacement, strain in reinforcing bars, energy dissipated at plastic hinges, and damage at section and frame levels. The results show that for low levels of seismic hazard, for which the structure is expected to perform basically within the elastic range, the accidental eccentricity is not a concern for the health of the structure, but it significantly increases the lateral displacement demand in the frames (about 30%) and this might cause significant damage to non-structural components. For high levels of seismic hazard the effects of accidental torsion become less important. These results underline the need to consider accidental eccentricity in evaluating the performance of a structure for very frequent or frequent earthquakes, and suggest that consideration of torsion may be neglected for performance levels associated with rare or very rare earthquakes

Shaking table tests of a RC frame structure equipped with hysteretic dampers

This paper provides partial results of an on-going research aimed at investigating the seismic response of reinforced concrete (RC) frames equipped with hysteretic-type energy dissipating devices (EDD). From a prototype RC frame structure designed only for gravity loads, a test model scaled in geometry to 2/5 was defined and built in the Laboratory of Structures of the University of Granada. Four EDDs were installed in the test model to provide the same seismic resistance than a conventional RC bare frame designed for sustain gravity and seismic loads following current codes. The test model with EDDs was subjected to several seismic simulations with the shaking table of Laboratory of structures of the University of Granada. The test results provide empirical evidences on the efficiency of the EDDs to prevent damage on the main frame and concentrating the inelastic deformations on the EDDs

A shake table test of typical mediterranean reinforced concrete structures

This research investigates the ultimate earthquake resistance of typical RC moment resisting frames designed accordingly to current standards, in terms of ultimate energy absorption/dissipation capacity. Shake table test of a 2/5 scale model, under several intensities of ground motion, are carried out. The loading effect of the earthquake is expressed as the total energy that the quake inputs to the structure, and the seismic resistance is interpreted as the amount of energy that the structure dissipates in terms of cumulative inelastic strain energy

¿Qué hay de nuevo en la Rizartrosis?

La rizartrosis en el momento actual está en periodo de avance, ya que nuevos descubrimientos biomecánicos sobre que ligamento es más importante para la estabilidad, e histológicos con el hallazgo de mecanoreceptores en los ligamentos abren un nuevo abanico de posibilidades terapéuticas con el control neuromuscular. La clasificación de Eaton y Littler sigue vigente actualmente, aunque hay nuevas propuestas como el índice radiológico para la artrosis del pulgar. El tratamiento poco ha variado, ya que la trapecectomía sigue siendo una opción válida, pero numerosas técnicas han sido desarrolladas, sin tener ningún estudio que confirme la superioridad de alguna con las demás. Últimamente, nuevas técnicas como la artroscopia, o la utilización de dispositivos tipo Tightrope®, se empiezan a utilizar, sin tener todavía estudios a largo plazo que nos indiquen si son realmente eficaces.Nowadays, osteoarthritis of the thumb is breakthrough time. Thaks to the new biomechanical findings which ligament is more important for stability, and the histological finding of tha mechanoreceptors in the ligaments, that open up a new range of therapeutic possibilities with neuromuscular control. The classification of Eaton and Littler is still currently in force, although there are new proposals as the radiological index for osteoarthritis of the thumb. Treatment has changed little, the trapeziectomy remains as an option, but many techniques have been developed without any studies that confirm the superiority of one with the other ones. Recently, new techniques such as arthroscopy, or use Tightrope® type devices are beginning to use, without yet having longterm studies that tell us whether they are really effective

Optimización y revalidación del análisis de nitrógeno por el método

En el presente artículo, se ha optimizado y se ha revalidado el procedimiento de análisis de nitrógeno en muestras de taurina mediante el método Kjeldahl. La Asociación Española de Farmacéuticos de la Industria (AEFI) propone un modelo de cálculo que permite determinar el número de replicados a realizar, en función del coeficiente de variación de la repetibilidad del procedimiento (C.V.%) y el valor límite aceptado, que en el caso de la determinación de la pureza, corresponde al valor máximo o mínimo de las especificaciones de la muestra. Al aplicar dicho modelo, considerando la incertidumbre de calibración del equipo, como el mínimo valor posible para el C.V.%, y teniendo en cuenta las especificaciones establecidas para la taurina en la U.S. Pharmacopeia 30, se obtiene que el número de replicados a realizar es de cinco o seis, según las condiciones de trabajo

Adenocarcinoma in Caroli's Disease Treated by Liver Transplantation

Caroli's disease is characterized by congenital cystic dilatation of the intrahepatic bile ducts. In 7% of casea a malignant tumor develops complicating the course of the disease

Perles supposées en variscite du sud-est de la France (Arles-Fontvieille, IVe mill. av. J.-C.) : premiers résultats d’une recherche en devenir

International audiencePutative variscite beads, discovered in megalithic monuments of Arles Fontvieille (Bouches-du- Rhône, France) used at the end of the Neolithic period (3400 to 2200 BC) are a relatively unknown and still unpublished corpus. It includes 116 beads. Since its discovery in the nineteenth century, in fact, this corpus has not been thoroughly analysed, neither from the geographical origin of the raw material used, nor from the technolgical point of view of their very method of production. This paper provides the first results of an ongoing research project. Thus, macroscopic observations at the stereo microscope, suggests that the body is not entirely composed of variscite, but that other rocks have been potentially used (sericite? muscovite?). On the mean time, a link is to be done between the raw material used and the beads’ morphology. These observations, which will be soon verified by PIXE analysis already raise several questions : what are the different origins of the beads, what is their manufacture process, what is the timeline of their production, etc. ? This article presents for the first time the new research agenda that emerges from the detailed analysis of the corpus.Les perles supposées en variscite découvertes au sein des monuments mégalithiques d’Arles-Fontvieille (Bouches-du-Rhône, France) utilisés à la fin du Néolithique (3400-2200 av. J.-C.) constituent un corpus relativement méconnu et encore inédit. Il comprend 116 perles au total. Depuis sa découverte au XIXe s., en effet, ce corpus n’a fait l’objet d’aucune analyse approfondie, qu’il s’agisse d’étudier la matière première, d’en identifier l’origine, de caractériser les types d’objets et leurs modes de production, notamment. Ce travail, actuellement en cours, livre de premiers résultats. Ainsi, l’observation macroscopique des perles à la loupe binoculaire, en particulier, suggère-t-elle que le corpus n’est pas intégralement composé de variscite, d’autres roches ont potentiellement été utilisées (séricite ? muscovite ?). De même, un lien semble pouvoir être établi entre la matière et la morphologie des pièces. Ces observations, qui seront vérifiées prochainement par des analyses PIXE, soulèvent déjà plusieurs interrogations : quelles sont les différentes origines des perles ? De quels processus opératoires procèdentelles ? Quelle chronologie s’attache à ces productions ? etc. Cet article expose pour la première fois ces nouvelles problématiques de recherche qui émergent à partir de l’analyse approfondie de ces corpus

Dissolved organic carbon bioreactivity and DOC:DIN stoichiometry control ammonium uptake in an intermittent Mediterranean stream

1. Heterotrophic organisms in streams use dissolved organic carbon (DOC) and dissolved inorganic nitrogen (DIN) from the water column to meet their growth and energy requirements. However, the role of DOC availability in driving DIN uptake in headwater streams is still poorly understood. In this study, we focus on how DOC:DIN stoichiometry and DOC bioreactivity control ammonium (NH$_4$$^+$) uptake and heterotrophic aerobic respiration, and how this influence varies among seasons in a forested Mediterranean headwater stream. 2. We estimated in-stream NH$_4$$^+$ uptake rates seasonally by conducting whole-reach constant-rate additions of NH$_4$$^+$ with and without amendments of either lignin (recalcitrant DOC) or acetate (labile DOC). During each addition, we characterised microbial community composition by molecular analyses, stream metabolism with the single-station method, and heterotrophic aerobic respiration by adding a metabolic tracer (resazurin). 3. The stream was heterotrophic (net ecosystem production 800% higher during the co-additions of acetate than when adding NH$_4$$^+$ either alone or with lignin. 4. Our results indicate that in-stream NH$_4$$^+$ uptake was largely controlled by heterotrophic bacteria, and that the stoichiometric balance between organic resources and nutrients was key to explaining the variability of in-stream NH$_4$$^+$ uptake and heterotrophic aerobic respiration. Moreover, the observed increase in NH$_4$$^+$ uptake during acetate additions suggests that heterotrophic activity was limited by labile DOC availability. 5. Our study highlights that both DOC:DIN stoichiometry and DOC bioreactivity are relevant factors driving the seasonal pattern of in-stream N processing in this forested Mediterranean headwater stream

Light inhibition of foliar respiration in response to soil water availability and seasonal changes in temperature Mediterranean holm oak. (quercus ilex forest)

In the present study we investigated variations in leaf respiration in darkness (RD) and light (RL), and associated traits in response to season, and along a gradient of soil moisture, in Mediterranean woodland dominated by holm oak (Quercus ilex L.) in central and north-eastern Spain respectively. On seven occasions during the year in the central Spain site, and along the soil moisture gradient in north-eastern Spain, we measured rates of leaf RD, RL (using the Kok method), light-saturated photosynthesis (A) and related light response characteristics, leaf mass per unit area (MA) and leaf nitrogen (N) content. At the central Spain site, significant seasonal changes in soil water content and ambient temperature (T) were associated with changes in MA, foliar N, A and stomatal conductance. RD measured at the prevailing daily T and in instantaneous R-T responses, displayed signs of partial acclimation and was not significantly affected by time of year. RL was always less than, and strongly related to, RD, and RL/RD did not vary significantly or systematically with seasonal changes in T or soil water content. Averaged over the year, RL/RD was 0.66 ± 0.05 s.e. (n = 14) at the central Spain site. At the north-eastern Spain site, the soil moisture gradient was characterised by increasing MA and RD, and reduced foliar N, A, and stomatal conductance as soil water availability decreased. Light inhibition of R occurred across all sites (mean RL/RD = 0.69 ± 0.01 s.e. (n = 18)), resulting in ratios of RL/A being lower than for RD/A. Importantly, the degree of light inhibition was largely insensitive to changes in soil water content. Our findings provide evidence for a relatively constrained degree of light inhibition of R (RL/RD ~ 0.7, or inhibition of ~30%) across gradients of water availability, although combined impacts of seasonal changes in both T and soil water content increase the range of values expressed. The findings thus have implications in terms of the assumptions made by predictive models that seek to account for light inhibition of R, and for our understanding of how environmental gradients impact on leaf trait relationships in Mediterranean plant communities