5,245 research outputs found

    Opportunistic linked data querying through approximate membership metadata

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    Between URI dereferencing and the SPARQL protocol lies a largely unexplored axis of possible interfaces to Linked Data, each with its own combination of trade-offs. One of these interfaces is Triple Pattern Fragments, which allows clients to execute SPARQL queries against low-cost servers, at the cost of higher bandwidth. Increasing a client's efficiency means lowering the number of requests, which can among others be achieved through additional metadata in responses. We noted that typical SPARQL query evaluations against Triple Pattern Fragments require a significant portion of membership subqueries, which check the presence of a specific triple, rather than a variable pattern. This paper studies the impact of providing approximate membership functions, i.e., Bloom filters and Golomb-coded sets, as extra metadata. In addition to reducing HTTP requests, such functions allow to achieve full result recall earlier when temporarily allowing lower precision. Half of the tested queries from a WatDiv benchmark test set could be executed with up to a third fewer HTTP requests with only marginally higher server cost. Query times, however, did not improve, likely due to slower metadata generation and transfer. This indicates that approximate membership functions can partly improve the client-side query process with minimal impact on the server and its interface

    In Situ Bragg Coherent Diffraction Imaging Study of a Cement Phase Microcrystal during Hydration

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    Results of Bragg coherent diffraction imaging (BCDI) confirm that ion migration and consumption occur during hydration of calcium monoaluminate (CA). The chemical phase transformation promotes the hydration process and the formation of new hydrates. There is a potential for the formation of hydrates near where the active ions accumulate. BCDI has been used to study the in situ hydration process of CA over a 3 day period. The evolution of three-dimensional (3D) Bragg diffraction electron density, the “Bragg density”, and strain fields present on the nanoscale within the crystal was measured and visualized. Initial Bragg densities and strains in CA crystal derived from sintering evolve into various degrees during hydration. The variation of Bragg density within the crystal is attributed to the change of the degree of crystal ordering, which could occur through ion transfer during hydration. The observed strain, coming from the interfacial mismatch effect between high Bragg density and low Bragg density parts in the crystal, remained throughout the experiment. The first Bragg density change during the hydration process is due to a big loss of Bragg density as seen in the image amplitude but not its phase. This work provides new evidence supporting the through-solution reaction mechanism of CA

    La imagen de la juventud en la publicidad televisiva

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    El Consejo Audiovisual de Navarra, máxima autoridad audiovisual en la Comunidad Foral de Navarra, tiene entre sus funciones básicas la elaboración de estudios que aporten luz al complejo y cambiante panorama audiovisual. Por esta razón se encomendó a la Facultad de Comunicación de la Universidad de Navarra la elaboración de este informe que analiza en profundidad la imagen de la juventud en la publicidad televisiva. Este Consejo Audiovisual espera haber ayudado de esta manera a fomentar la protección de la juventud en su exposición a los medios audiovisuales y a mejorar la imagen que de ella se da especialmente en la televisión, uno de los mayores factores de socialización, sino el que más, de los jóvenes de nuestra sociedad

    L'Espectrometria de masses aplicada a la caracterització de materials

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    En aquest article hom pretén revisar en primer lloc, els principis de funcionament d'un espectròmetre de masses així com els principals desenvolupaments experimentals que aquesta tècnica ha assolit en l'actualitat. Per aquesta raó hom discutirà sobre diferents fonts d'ionització tant clàssiques (impacte electrònic, ionització química...) com d'altres dissenyades per a analitzar materials no volàtils. El concepte d'espectròmetre de doble enfocament també serà revisat. Hom introduirà els principis bàsics que permeten d'obtenir les anàlisi SIMS (Secondary Ion Mass Spectrometry) i els anomenats "ion imaging". Ha merescut una atenció especial la disposició FAB-CAD-MIKES (Fast Atom Bombardment – Collission Activated Decay- Mass Analysed Ion Kinetic Energy Spectrometry). També seran presentades algunes experiències realitzades amb aquestes tècniques.This paper reviews firstly the basis of a mass spectrometer and the main experimental developments reachead by this technique up to now. Different classical ionization sources (such as electron impact,chemical ionization ) and those developed for the analysis of non volatile materials as well as the concept of double focalization mass spectrometer will be discussed. Furthermore the principles of S.I.M.S. analysis and ion imaging, will be considered. Special attention will be devoted to the joint application of F.A.B.-C.A.D.-M.I.K.E.S. techniques. Finally, some experiences carried out with these techniques are reported

    SEOM clinical guidelines for diagnosis and treatment of metastatic colorectal cancer 2015

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    Colorectal cancer (CRC) is the second leading cause of cancer dead in Spain. About half the patients will eventually develop distant metastases. However, as treatment options are expanding, prognosis has steadily improved over the last decades. Management of advanced CRC should be discussed within an experienced multidisciplinary team to select the most appropriate systemic treatment (chemotherapy and targeted agents) and to integrate surgical or ablative procedures when indicated. Disease site and extent, resectability, tumor biology and gene mutations, clinical presentation, patient preferences, and comorbidities are key factors to design a customized treatment plan. The aim of these guidelines is to provide synthetic recommendations for managing advanced CRC patients

    An A4 flavor model for quarks and leptons in warped geometry

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    We propose a spontaneous A4 flavor symmetry breaking scheme implemented in a warped extra dimensional setup to explain the observed pattern of quark and lepton masses and mixings. The main advantages of this choice are the explanation of fermion mass hierarchies by wave function overlaps, the emergence of tribimaximal neutrino mixing and zero quark mixing at the leading order and the absence of tree-level gauge mediated flavor violations. Quark mixing is induced by the presence of bulk flavons, which allow for cross-brane interactions and a cross-talk between the quark and neutrino sectors, realizing the spontaneous symmetry breaking pattern A4 --> nothing first proposed in [X.G.\,He, Y.Y.\,Keum, R.R.\,Volkas, JHEP{0604}, 039 (2006)]. We show that the observed quark mixing pattern can be explained in a rather economical way, including the CP violating phase, with leading order cross-interactions, while the observed difference between the smallest CKM entries V_{ub} and V_{td} must arise from higher order corrections. We briefly discuss bounds on the Kaluza-Klein scale implied by flavor changing neutral current processes in our model and show that the residual little CP problem is milder than in flavor anarchic models.Comment: 34 pages, 2 figures; version published in JHE

    Fine-root turnover rates of European forests revisited: an analysis of data from sequential coring and ingrowth cores

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    Background and Aims: Forest trees directly contribute to carbon cycling in forest soils through the turnover of their fine roots. In this study we aimed to calculate root turnover rates of common European forest tree species and to compare them with most frequently published values. Methods: We compiled available European data and applied various turnover rate calculation methods to the resulting database. We used Decision Matrix and Maximum-Minimum formula as suggested in the literature. Results: Mean turnover rates obtained by the combination of sequential coring and Decision Matrix were 0.86yr−1 for Fagus sylvatica and 0.88yr−1 for Picea abies when maximum biomass data were used for the calculation, and 1.11yr−1 for both species when mean biomass data were used. Using mean biomass rather than maximum resulted in about 30% higher values of root turnover. Using the Decision Matrix to calculate turnover rate doubled the rates when compared to the Maximum-Minimum formula. The Decision Matrix, however, makes use of more input information than the Maximum-Minimum formula. Conclusions: We propose that calculations using the Decision Matrix with mean biomass give the most reliable estimates of root turnover rates in European forests and should preferentially be used in models and C reportin

    Epigenetic Signatures Associated with Different Levels of Differentiation Potential in Human Stem Cells

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    The therapeutic use of multipotent stem cells depends on their differentiation potential, which has been shown to be variable for different populations. These differences are likely to be the result of key changes in their epigenetic profiles

    Four-dimensional distribution of the 2010 Eyjafjallajökull volcanic cloud over Europe observed by EARLINET

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    © Author(s) 2013. This work is distributed under the Creative Commons Attribution 3.0 License.The eruption of the Icelandic volcano Eyjafjallaj ökull in April-May 2010 represents a "natural experiment" to study the impact of volcanic emissions on a continental scale. For the first time, quantitative data about the presence, altitude, and layering of the volcanic cloud, in conjunction with optical information, are available for most parts of Europe derived from the observations by the European Aerosol Research Lidar NETwork (EARLINET). Based on multi-wavelength Raman lidar systems, EARLINET is the only instrument worldwide that is able to provide dense time series of high-quality optical data to be used for aerosol typing and for the retrieval of particle microphysical properties as a function of altitude. In this work we show the four-dimensional (4-D) distribution of the Eyjafjallajökull volcanic cloud in the troposphere over Europe as observed by EARLINET during the entire volcanic event (15 April-26 May 2010). All optical properties directly measured (backscatter, extinction, and particle linear depolarization ratio) are stored in the EARLINET database available at www.earlinet.org. A specific relational database providing the volcanic mask over Europe, realized ad hoc for this specific event, has been developed and is available on request at www.earlinet.org. During the first days after the eruption, volcanic particles were detected over Central Europe within a wide range of altitudes, from the upper troposphere down to the local planetary boundary layer (PBL). After 19 April 2010, volcanic particles were detected over southern and south-eastern Europe. During the first half of May (5-15 May), material emitted by the Eyjafjallajökull volcano was detected over Spain and Portugal and then over the Mediterranean and the Balkans. The last observations of the event were recorded until 25 May in Central Europe and in the Eastern Mediterranean area. The 4-D distribution of volcanic aerosol layering and optical properties on European scale reported here provides an unprecedented data set for evaluating satellite data and aerosol dispersion models for this kind of volcanic events.Peer reviewe
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