2,682 research outputs found

    Wind loads analysis at the anchorages of the Talavera de la Reina cable stayed bridge

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    This paper describes wind tunnel tests performed on wind tunnel models of the Talavera de la Reina cable stayed bridge. The work describes the aeroelastic model construction and it is focused on the evaluation and analysis of the mean and peak wind loads at the tower foundation and the cable anchorages since these data can be very useful by the bridge manufacturer as a support for the bridge design. The work is part of a complete wind tunnel study carried out to analyze the aeroelastic stability of the bridge

    On the connection of fractures with clays and fluids in the accretionary prism of the Nankai Trough at Site C0002, NanTroSEIZE IODP Expedition 338/348. Borehole images and log interpretation results

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    International Ocean Discovery Program IODP has extensively used the D/V Chikyu to drill the Kumano portion of the Nankai Trough. (IODP) Expeditions 338 and 348 of the NanTroSEIZE project drilled deep into the inner accretionary prism south of the Kii Peninsula collecting a suite of LWD data, including natural gamma ray, electrical resistivity logs and borehole images, suitable to characterize structures (fractures and faults) inside the accretionary prism. Both expeditions drilled into the accretionary prism at Site C0002: Hole C0002F (Expedition 338) was drilled down to 2004.5 mbsf, Hole C0002P (Expedition 348) reached a depth of 3058.8 mbsf. Structural interpretation and analysis of logging-while-drilling data in the deep inner prism revealed intense deformation of a generally homogenous bedding that dips steeply and are intersected by faults and fractures. The interpretation of the images of both Hole C0002F and Hole C0002P reveals distinct areas of intense fracturing and faulting within a very clay-dominated lithology. Faults are undobutedly interpreted on C0002P images. The relationship between fractures, faults and the changes in clay mineralogy from cutting sample analyses is analyzed to characterize potential connection between these features in the accretionary prismM.J. Jurado research supported by PNIDI- CGL2009-13405, CGL2010-21568, and ACI2008-0773 projects.Peer Reviewe

    Marker based Thermal-Inertial Localization for Aerial Robots in Obscurant Filled Environments

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    For robotic inspection tasks in known environments fiducial markers provide a reliable and low-cost solution for robot localization. However, detection of such markers relies on the quality of RGB camera data, which degrades significantly in the presence of visual obscurants such as fog and smoke. The ability to navigate known environments in the presence of obscurants can be critical for inspection tasks especially, in the aftermath of a disaster. Addressing such a scenario, this work proposes a method for the design of fiducial markers to be used with thermal cameras for the pose estimation of aerial robots. Our low cost markers are designed to work in the long wave infrared spectrum, which is not affected by the presence of obscurants, and can be affixed to any object that has measurable temperature difference with respect to its surroundings. Furthermore, the estimated pose from the fiducial markers is fused with inertial measurements in an extended Kalman filter to remove high frequency noise and error present in the fiducial pose estimates. The proposed markers and the pose estimation method are experimentally evaluated in an obscurant filled environment using an aerial robot carrying a thermal camera.Comment: 10 pages, 5 figures, Published in International Symposium on Visual Computing 201

    Determinación del flujo de calor a partir de sondeos petroleros en la Cuenca Catalano-Balear

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    A method using information from oil wells has been applied to calculate heat flow at seven oil wells in the Valencia trough, a Neogene extensional basin located in the western Mediterranean. Most of these weils penetrate the Cenozoic sedimentary cover and the underlying Mesozoic sequences and the Paleozoic basement. The basic data set consists of well logs, rock samples including cuttings and cores, and bottom hole (BHT) and dril1 stem test (DST) temperature data. Thermal conductivity of the rock matrix is determined from the conductivities and volumetric fractions of its mineral components by using a geometrical mean model. The in-situ thermal conductivity profile is then obtained as a function of porosity, and it is corrected for in-situ temperature conditions. The sonic log has been used to estimate the porosity profile, which has been corrected depending on the clay content of the formation. Finally, vertical heat flow variation is calculated at every well by combining bulk thermal conductivity profile and geothermal gradients.The bulk thermal conductivity has been shown to be very sensitive to lithologic and porosity changes, with values that vary from 1.5 W m-K-' for shales with over 40 percent porosity, to about 4.3 W m-' K-' for dolomites and consolidated quartz-rich sandstones that constitute the basement. The maximum thermal conductivity values are attained for the basement materials and are due to the low porosity (caused by compaction and burial) and to the high matrix conductivities of Mesozoic carbonates and sandstones. The mean bulk thermal conductivity of the sediments is found to be about 2 W m-' K-l. Therefore, a thermal blanketing effect is likely to occur due to the conductivity contrast between the sedimentary cover and the underlying basement. This effect, which has been neglected in previous models of the thermal evolution of the Valencia trough, probably has acted to slow down post-extensional lithospheric cooling and to reduce tectonic subsidence.A regional thermal gradient of 3612 "C km-' is obtained from the available temperature data. This value is siightly lower than that estimated from a set of wells in the southwestern part of the basin. The calculated heat flow values are highly scattered, the maximum value being located in the southwestern part of the basin. As a consequence, the resulting heat flow agrees with the increase towards the SW previously observed in the Valencia trough. The mean heat flow value in the study area is determined to be 85-90 mW m-2. Although thermal conductivity could be overestimated, this value is too high to be just a consequence of the rifting process in the Valencia trough, since most of the wells considered are located in the northernmost part of the basin. The thermal effect of groundwater circulation is proposed to be in part responsible for the positive and negative thermal gradient anomalies.Fracturing and karstification, which has been widely recognized in the Mesozoic carbonates in the basement, together with the temperature data and porosity results, support this hypothesis

    DATA-LIMITED MIXED FISHERIES TARGETING DATA-POOR SPECIES: THE ARTISANAL PURSE-SEINE FLEET IN THE CANARY ISLANDS

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    In waters off The Canary Islands, small pelagic fish are targeted by an artisanal purse seine fleet. This fishery has been monitored within the EU Data Collection Framework since 2013. The status assessment of the most important commercial species (i.e. Scomber colias, Trachurus spp, Sardinella spp and Sardina pilchardus) are included in the Fishery Committee for the Eastern Central Atlantic (CECAF). However, the short time series and the limited knowledge of the life history traits of these species in the Archipelago had been considered too limited to perform any assessment exercise. In this context, a multi-model approach was attempted to assess the status of these species for the first time in the area, using the methods recommended by CECAF and the International Council for the Exploration of the Sea (ICES). Time series of landings and fishing effort includes data since 2009 to 2020, being less reliable at the beginning of the series. In addition, the biological and population information needed as input data in those models, are available depending on the species, this increasing the uncertainty of these analyses. A total of six data-limited (length- and catch-based) methods was applied. Results show that a quantitative assessment of the Canaries small pelagic stocks, with the final aim of providing scientific advice for management purposes, is not yet feasible. Therefore, it is necessary and urgent to address the current uncertainties around these species and fisheries, both by improving the knowledge of their life histories and by solving the shortfalls related to the data of this artisanal and multispecific fishery

    Estimación del valor marginal del agua de riego en olivar mediante el método de la función de producción

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    Economic valuation of irrigation water is done through the use of production functions for the case of the olive grove. In order to do so the integration of an agronomic model (based on the production function) and an economic model linked to the profitability of the crop (the ratio of revenue and operating costs) in the area under study is proposed. The study case encompasses the Guadalbullon River Sub-basin area, belonging to the Guadalquivir River Hydrologic Demarcation (Southern Spain). Within the overall deficit of the Guadalquivir River basin, the Guadalbullon River poses a special problem as it is unregulated and there are important irrigated fields on its banks, most of them olive groves. Net marginal value of water obtained (having deducted the variable costs of production including harvesting and irrigation) is € 0.60 m-3 for the allocation of 1,000 m3 ha-1 and € 0.53 m-3 for the water right allowance of 1,500 m3 ha3 (average for period 2005/2008). The results obtained support the recommendation by other authors suggesting the use of deficit irrigation in olive, additionally the high value of water estimated contributes to explain the substantial increase in irrigated olive area in Andalucia.This research was made possible thanks to funding support of the FPI help Program of the Ministry of Science and Innovation related to the research project called «Análisis prospectivo de la sostenibilidad de los sistemas agrarios nacionales en el marco de la PAC» (Ref AGL2006-05587-C04-02).Peer Reviewe

    Cytotoxicity and Membrane Interaction of Tamoxifen as Affected by Ca2+ and Mg2+: Use of a Bacterial Model System

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    A strain of Bacillus stearothermophilus was used as a model to study the interaction of tamoxifen (TAM) with the membrane and the cytostatic antiproliferative effects not related to estrogen binding. TAM inhibits the growth of B. stearothermophilus as a function of concentration. The supplementation of the growth medium with Ca2+ or Mg2+ partially relieves the growth inhibition by TAM, allowing growth at TAM concentrations that fully impair growth in the basal medium. Fluorescence polarization of 1,6-diphenyl-1,3,5-hexatriene (DPH) and of its propionic acid derivative (DPH-PA) reveals opposite effects induced by TAM and Ca2+. The addition of Ca2+ to liposomes of bacterial lipids promoted physical ordering as opposed to disordering induced by TAM. Thus, it is predictable that growth impairment induced by TAM is mediated through perturbations at the membrane level.http://www.sciencedirect.com/science/article/B6TCP-3X3K8KK-Y/1/c91ad40c71c69da7245d8f09c634d28

    Comparative study of tributyltin toxicity on two bacteria of the genus Bacillus

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    Tributyltin is a potent biocide mainly used in marine antifouling paints. Owing to its widespread distribution in coast areas and its high toxicity to aquatic organisms, the use of this compound is generally restricted and under government regulation. Despite of that, it persists in the aquatic environment. Organotins used in industry have also been detected in terrestrial environments. The persistence and high lipophilicity explain bioaccumulation. The role of bacteria in recycling organic matter prompted us to study the interaction of tributyltin with two ubiquitous bacilli, B. stearothermophilus and B. subtilis, proposed as biological indicators of pollutants with ecological impact. These bacteria have been used as suitable models for the study of toxicity mechanisms of unselective lipophilic compounds (e.g., DDT and endosulfan). Drug effects on growth parameters, oxygen consumption and membrane organization were assessed. Bacteria growth in a liquid complex medium was disturbed by concentrations of TBT as low as 25 nM (8 [mu]g L-1), close to the concentration in polluted environments. The respiratory activity is affected by TBT in both microorganisms. Membrane organization, assessed by fluorescence polarization of two fluidity probes, 1,6-diphenyl-1,3,5-hexatriene (DPH) and a propionic acid derivative (DPH-PA), was also perturbed by the xenobiotic. Alterations on growth, oxygen consumption and physical properties of membrane lipids are stronger in B. stearothermophilus as compared to B. subtilis. A putative relationship between growth inhibition and respiratory activity impairment induced by TBT and its effects on the physical behaviour of bacterial membrane lipids is suggested.http://www.sciencedirect.com/science/article/B6TCP-4GSJR3R-9/1/18e0ee5c8ce4e887466d84b850ad8ec

    Toxicity of methoprene as assessed by the use of a model microorganism

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    Methoprene is an insect juvenile growth hormone mimic, commonly used as a pesticide. Although widely used for the control of several pests, toxic effects on organisms of different phyla have been reported. These events triggered studies to clarify the mechanisms of toxicity of this insecticide putatively involved in ecological issues. Here we show the effect of methoprene on the normal cell growth and viability of a strain of the thermophilic eubacterium Bacillus stearothermophilus, previously used as a model for toxicological evaluation of other environment pollutants. Respiration studies were also carried out attempting to identify a putative target for the cytotoxic action of methoprene. Cell growth was affected and a decrease of the number of viable cells was observed as a result of the addition of methoprene to the growth medium, an effect reverted by the presence of Ca2+. Methoprene also inhibited the redox flow of B. stearothermophilus protoplasts before the cytochrome oxidase segment, an effect further studied by individually assessing the enzymatic activities of the respiratory complexes. This study suggests that methoprene membrane interaction and perturbation of cell bioenergetics may underlie the mechanism of toxicity of this compound in non-target organisms.http://www.sciencedirect.com/science/article/B6TCP-4GSJXGW-4/1/788f9fd7d4f3a4f1ae5d498a5674dcc
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