744 research outputs found

    Geomatic methods applied to the change study of the la Paúl Rock Glacier, Spanish Pyrenees

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    Producción CientíficaRock glaciers are one of the most important features of the mountain permafrost in the Pyrenees. La Paúl is an active rock glacier located in the north face of the Posets massif in the La Paúl glacier cirque (Spanish Pyrenees). This study presents the preliminary results of the La Paúl rock glacier monitoring works carried out through two geomatic technologies since 2013: Global Navigation Satellite System (GNSS) receivers and Terrestrial Laser Scanning (TLS) devices. Displacements measured on the rock glacier surface have demonstrated both the activity of the rock glacier and the utility of this equipment for the rock glaciers dynamic analysis. The glacier has exhibited the fastest displacements on its west side (over 35 cm yr-1), affected by the Little Ice Age, and frontal area (over 25 cm yr-1). As an indicator of permafrost in marginal environments and its peculiar morphology, La Paúl rock glacier encourages a more prolonged study and to the application of more geomatic techniques for its detailed analysis.Ministerio de Economía, Industria y Competitividad - Fondo Europeo de Desarrollo Regional (project CGL2015-68144-R)Junta de Extremadura - Fondo Europeo de Desarrollo Regional (project GR10071

    Influence of the Growing Conditions in the Content of Vitamin C in Diplotaxis erucoides

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    Diplotaxis erucoides is an edible plant with potential for marketing. Here, we analysed the influence of the growing conditions in this species, D. tenuifolia and Eruca sativa, and studied the relation among the ascorbic (AA) and dehydroascorbic (DHA) acid forms. Plants were grown in the late winter-spring season under two conditions, greenhouse and field. The contents in AA, DHA and vitamin C (VC) were analysed by HPLC. The content of VC and AA were, in general, remarkable higher in the plants grown in the field. On the other hand, the mean percentage of DHA was less than 11%, being in this case higher for plants grown in the greenhouse. Thus, growing this potential crop in the field seems a better option in order to increase the content in VC, being AA the main form present at the moment of gathering

    Modelo de competencia docente del profesor de medicina en la UNAM

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    El estudio presenta un modelo de competencia docente del profesor de medicina. Fue generado a partir de un modelo conceptual preexistente: a) dicho modelo se sometió al juicio de expertos quienes seleccionaron las competencias de mayor impacto; b) se construyó un perfil de competencias; c) se generó un instrumento basado en la opinión de los estudiantes y otro de autoevaluación; d) ambos fueron validados por 18 expertos en evaluación; e) se aplicó a 2,281 estudiantes y 107 profesores, obteniendo un comportamiento psicométrico adecuado que permitió establecer un modelo acorde a las tendencias actuales en evaluación del desempeño docente

    The Sound Emission Board of the KM3NeT Acoustic Positioning System

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    We describe the sound emission board proposed for installation in the acoustic positioning system of the future KM3NeT underwater neutrino telescope. The KM3NeT European consortium aims to build a multi-cubic kilometre underwater neutrino telescope in the deep Mediterranean Sea. In this kind of telescope the mechanical structures holding the optical sensors, which detect the Cherenkov radiation produced by muons emanating from neutrino interactions, are not completely rigid and can move up to dozens of meters in undersea currents. Knowledge of the position of the optical sensors to an accuracy of about 10 cm is needed for adequate muon track reconstruction. A positioning system based on the acoustic triangulation of sound transit time differences between fixed seabed emitters and receiving hydrophones attached to the kilometre-scale vertical flexible structures carrying the optical sensors is being developed. In this paper, we describe the sound emission board developed in the framework of KM3NeT project, which is totally adapted to the chosen FFR SX30 ultrasonic transducer and fulfils the requirements imposed by the collaboration in terms of cost, high reliability, low power consumption, high acoustic emission power for short signals, low intrinsic noise and capacity to use arbitrary signals in emission mode.Comment: 9 pages, 4 figure

    Managing daily surgery schedules in a teaching hospital: a mixed-integer optimization approach

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    Background: This study examined the daily surgical scheduling problem in a teaching hospital. This problem relates to the use of multiple operating rooms and different types of surgeons in a typical surgical day with deterministic operation durations (preincision, incision, and postincision times). Teaching hospitals play a key role in the health-care system; however, existing models assume that the duration of surgery is independent of the surgeon's skills. This problem has not been properly addressed in other studies. We analyze the case of a Spanish public hospital, in which continuous pressures and budgeting reductions entail the more efficient use of resources. Methods: To obtain an optimal solution for this problem, we developed a mixed-integer programming model and user-friendly interface that facilitate the scheduling of planned operations for the following surgical day. We also implemented a simulation model to assist the evaluation of different dispatching policies for surgeries and surgeons. The typical aspects we took into account were the type of surgeon, potential overtime, idling time of surgeons, and the use of operating rooms. Results: It is necessary to consider the expertise of a given surgeon when formulating a schedule: such skill can decrease the probability of delays that could affect subsequent surgeries or cause cancellation of the final surgery. We obtained optimal solutions for a set of given instances, which we obtained through surgical information related to acceptable times collected from a Spanish public hospital. Conclusions: We developed a computer-aided framework with a user-friendly interface for use by a surgical manager that presents a 3-D simulation of the problem. Additionally, we obtained an efficient formulation for this complex problem. However, the spread of this kind of operation research in Spanish public health hospitals will take a long time since there is a lack of knowledge of the beneficial techniques and possibilities that operational research can offer for the health-care system

    Impact of the atmospheric climate modes on wave climate in the North Atlantic

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    Trabajo presentado en la EGU General Assemby 2014, celebrada del 27 de abril al 2 de mayo de 2014 en Viena (Austria)This study establishes the relationships between the mean modes of atmospheric variability in the North Atlantic and present wave climate. The modes considered, namely the North Atlantic Oscillation (NAO), the East Atlantic pattern (EA), the East Atlantic Western Russian pattern (EA/WR) and the Scandinavian pattern (SCAN), are obtained from the NOAA Climate Prediction Centre. The wave data sets used consist of buoy records and two high-resolution simulations of significant wave height (SWH), mean wave period (MWP) and mean wave direction (MWD) forced with ERA-40 (1958-2002) and ERA-INTERIM (1989-2008) wind fields. The results show the winter impact of each mode on wave parameters which are discussed regionally. The NAO and EA pattern increase winter SWH up to 1 m per unit index at the Scottish and Spanish coasts, respectively, during their positive phase; while EA pattern causes clockwise changes of winter MWD up to more than 60 degrees per unit index at the Bay of Biscay during its negative phase. EA/WR and SCAN patterns have a weaker impactPeer Reviewe

    Development of an acoustic transceiver for the KM3NeT positioning system

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    [EN] In this paper we describe an acoustic transceiver developed for the KM3NeT positioning system. The acoustic transceiver is composed of a commercial free flooded transducer, which works mainly in the 20-40 kHz frequency range and withstands high pressures (up to 500 bars). A sound emission board was developed that is adapted to the characteristics of the transducer and meets all requirements: low power consumption, high intensity of emission, low intrinsic noise, arbitrary signals for emission and the capacity of acquiring the receiving signals with very good timing precision. The results of the different tests made with the transceiver in the laboratory and shallow sea water are described, as well as, the activities for its integration in the Instrumentation Line of the ANTARES neutrino telescope and in a NEMO tower for the in situ tests. © 2012 Elsevier B.V. All rights reserved.This work has been supported by the Ministerio de Ciencia e Innovacion (Spanish Government), Project references FPA2009-13983-C02-02, ACI2009-1067, AIC10-D-00583, and Consolider-Ingenio Multidark (CSD2009-00064). It has also been funded by Generalitat Valenciana, Prometeo/2009/26, and the European 7th Framework Programme, Grant no. 212525.Larosa, G.; Ardid Ramírez, M.; Llorens Alvarez, CD.; Bou Cabo, M.; Martínez Mora, JA.; Adrián Martínez, S.; KM3NeT Consortium (2013). Development of an acoustic transceiver for the KM3NeT positioning system. Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment. 725:215-218. https://doi.org/10.1016/j.nima.2012.11.167S21521872

    Design of graphene-based TiO2 photocatalysts - A review

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    There is a recent increase in the interest of de- signing high-performance photocatalysts using graphene- based materials. This review gathers some important aspects of graphene–TiO 2 , graphene oxide–TiO 2 , and reduced gra- phene oxide–TiO 2 composites, which are of especial rele- vance as next generation photocatalysts. The methods used for the preparation of these materials, the associated mech- anistic fundamentals, and the application of graphene-based composites on the photocatalytic degradation of pollutants are reviewed. Some structural, textural, and chemical prop- erties of these materials and other photo-assisted applica- tions, such as hydrogen production from water splitting and dye-sensitized solar cells, are also briefly includedFinancial support for this work was provided by the European Commission (Clean Water—grant agreement no 227017) and by Fundação para a Ciência e a Tecnologia (FCT) and FEDER under Program COMPETE, project FCOMP-01-0124-FEDER-022706 (Ref. FCT Pest-C/EQB/LA0020/2011) and FCOMP-01-0124-FEDER- 008442 (Ref. NANO/NTec-CA/0046/2007). Clean Water is a Collab- orative Project co-funded by the Research DG of the European Com- mission within the joint RTD activities of the Environment and NMP Thematic Priorities. SMT and AMTS acknowledge financial support from SFRH/BPD/74239/2010 and POCI/N010/2006, respectively
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