1,501 research outputs found

    Developing Intensity-Duration-Frequency (IDF) Curves From Satellite-Based Precipitation: Methodology and Evaluation

    Get PDF
    Given the continuous advancement in the retrieval of precipitation from satellites, it is important to develop methods that incorporate satellite-based precipitation data sets in the design and planning of infrastructure. This is because in many regions around the world, in situ rainfall observations are sparse and have insufficient record length. A handful of studies examined the use of satellite-based precipitation to develop intensity-duration-frequency (IDF) curves; however, they have mostly focused on small spatial domains and relied on combining satellite-based with ground-based precipitation data sets. In this study, we explore this issue by providing a methodological framework with the potential to be applied in ungauged regions. This framework is based on accounting for the characteristics of satellite-based precipitation products, namely, adjustment of bias and transformation of areal to point rainfall. The latter method is based on previous studies on the reverse transformation (point to areal) commonly used to obtain catchment-scale IDF curves. The paper proceeds by applying this framework to develop IDF curves over the contiguous United States (CONUS); the data set used is Precipitation Estimation from Remotely Sensed Information Using Artificial Neural Networks – Climate Data Record (PERSIANN-CDR). IDFs are then evaluated against National Oceanic and Atmospheric Administration (NOAA) Atlas 14 to provide a quantitative estimate of their accuracy. Results show that median errors are in the range of (17–22%), (6–12%), and (3–8%) for one-day, two-day and three-day IDFs, respectively, and return periods in the range (2–100) years. Furthermore, a considerable percentage of satellite-based IDFs lie within the confidence interval of NOAA Atlas 14

    Porosity measurements of interstellar ice mixtures using optical laser interference and extended effective medium approximations

    Get PDF
    Aims. This article aims to provide an alternative method of measuring the porosity of multi-phase composite ices from their refractive indices and of characterising how the abundance of a premixed contaminant (e.g., CO2) affects the porosity of water-rich ice mixtures during omni-directional deposition. Methods. We combine optical laser interference and extended effective medium approximations (EMAs) to measure the porosity of three astrophysically relevant ice mixtures: H2O:CO2=10:1, 4:1, and 2:1. Infrared spectroscopy is used as a benchmarking test of this new laboratory-based method. Results. By independently monitoring the O-H dangling modes of the different water-rich ice mixtures, we confirm the porosities predicted by the extended EMAs. We also demonstrate that CO2 premixed with water in the gas phase does not significantly affect the ice morphology during omni-directional deposition, as long as the physical conditions favourable to segregation are not reached. We propose a mechanism in which CO2 molecules diffuse on the surface of the growing ice sample prior to being incorporated into the bulk and then fill the pores partly or completely, depending on the relative abundance and the growth temperature.Comment: 9 pages, 6 figures, 1 table. Accepted for publication in A&

    Innovar la educación en ciencias a través de enseñar y aprender acerca de la naturaleza de Ciencia y Tecnología

    Get PDF
    Esta comunicación contribuye a lema del congreso tratando de mejorar la enseñanza de la ciencia a través de una propuesta innovadora parapromover la comprensión del funcionamiento actual de la ciencia y tecnología en la sociedad (CTS),transformando las propuestas de la investigación didácticaen instrumentos útiles para los profesores en el aula. Describe las líneas básicas de un proyecto de investigación (EANCYT, Enseñanza y aprendizaje de naturaleza de la ciencia y la tecnología, NdCyT) que afronta el problema educativo de enseñar NdCyT con calidad y eficacia en países latinos.Elpropósito central es presentar los aspectos comunesdel proyecto y del simposio, es decir, los fundamentos teóricos y didácticos para enseñarcontenidos de NdCyT, que se apoyan en tres ejes básicos: la investigación sobre NdCyT, sobre secuencias de enseñanza-aprendizaje y las teorías del aprendizaje de la ciencia.Los aspectos innovadores de la comunicación se centran en el diseño de las secuencias de enseñanza aprendizaje (SEA) a aplicar en el aula, los instrumentos de evaluación de la mejora del aprendizaje de los estudiantes y el diseño empírico de la investigación para la verificación de la eficacia de las SEAs

    An analysis of interplanetary solar radio emissions associated with a coronal mass ejection

    Full text link
    Coronal mass ejections (CMEs) are large-scale eruptions of magnetized plasma that may cause severe geomagnetic storms if Earth-directed. Here we report a rare instance with comprehensive in situ and remote sensing observa- tions of a CME combining white-light, radio, and plasma measurements from four different vantage points. For the first time, we have successfully applied a radio direction-finding technique to an interplanetary type II burst detected by two identical widely separated radio receivers. The derived locations of the type II and type III bursts are in general agreement with the white light CME recon- struction. We find that the radio emission arises from the flanks of the CME, and are most likely associated with the CME-driven shock. Our work demon- strates the complementarity between radio triangulation and 3D reconstruction techniques for space weather applications

    PLA scaffolds production from Thermally Induced Phase Separation: effect of process parameters and development of an environmentally improved route assisted by supercritical carbon dioxide

    Get PDF
    In this work, a relatively large scale of PLA scaffolds was produced using thermally induced phase separation (TIPS) combined with a supercritical carbon dioxide (SC-CO2) drying step as a green alternative. For the TIPS step, the phase separation of PLA and 1,4-dioxane solvent was controlled by adjusting the process conditions such as the polymer concentration and molecular weight, the 1,4-dioxane solvent power and the cooling conditions. The scaffolds morphology was analyzed by scanning electron microscopy. Their structural and mechanical properties were correlated together with the possibility to tune them by controlling the process conditions. An environmental analysis using the Life Cycle Assessment (LCA) methodology confirmed a reduction of at least 50% of the environmental impact of the whole process using the SC-CO2 drying compared to the traditional freeze-drying technology. This work is the first known attempt to conduct the LCA methodology on TIPS process for the PLA scaffolds production

    TLR3 MATURATION, LOCALISATION AND APOPTOTIC ROLE IN CANCER

    Get PDF
    Oral Communication presented at the ";Forum des Jeunes Chercheurs";, Brest (France) 2011

    Estandardització i marcadors tumorals

    Get PDF
    corecore