844 research outputs found

    Characterization of a buried paleosol under the upper tertiary sediments of As Pontes de García Rodríguez. (A Coruña, Galice, NW Spain)

    Get PDF
    [Resumen] Se estudia un perfil de meteorización y edáfico sobre filitas que se encuentra enterrado bajo los sedimentos de la cuenca terciaria de As Pontes de García Rodríguez (NO de España). El análisis mineralógico y los rasgos micromorfológicos (esferosideritas) ponen de manifiesto que el proceso edafogenético se desarrolló bajo dos paleoambientes sucesivos: El inicial, bajo condiciones subaéreas, conduce a la formación de caolinita y goethita; el segundo, con hidromorfía permanente, afecta fundamentalmente a los compuestos de hierro, originándose siderita. Como ayuda para entender los antiguos procesos, se analiza un perfil situado en el borde de la cuenca.[Abstract] A soil profile developed from phyllites is studied, it is located under the sediments of the Tertiary basin of As Pontes de García Rodríguez (NW Spain). The mineralogical analysis and the micromorphological features show mat the pedogenetic process comprissed two successive paleoenvironmental steps: The initial stage under subaeric conditions, let to the formation of kaolinite and goethite. During the second one, under permanent hydromorphic conditions, the main feature was a redistribution of iron compounds, with the formation of siderite. For the understanding of paleoprocesses, a present hydromorphous profile located on the basin margen is also studied and compared

    An evaluation resource for geographic information retrieval

    Get PDF
    In this paper we present an evaluation resource for geographic information retrieval developed within the Cross Language Evaluation Forum (CLEF). The GeoCLEF track is dedicated to the evaluation of geographic information retrieval systems. The resource encompasses more than 600,000 documents, 75 topics so far, and more than 100,000 relevance judgments for these topics. Geographic information retrieval requires an evaluation resource which represents realistic information needs and which is geographically challenging. Some experimental results and analysis are reported

    Granite paleoweathering: A case-study under the tertiary deposit of Xinzo de Limia

    Get PDF
    [Resumen] Se estudia una paleoalteración desarrollada sobre granito y situada bajo un espesor de 120 m. de sedimentos en la cuenca terciaria de Xinzo de Limia (Ourense). El cambio minera16gico más significativo es la transformaci6n de las plagioclasas en caolinita. Se detectan también pequeñas proporciones de esmectitas. El estudio geoquímico revela una clara lixiviaci6n de bases, como lo pone de manifiesto la disminución de todos los índices de alteración (Indices de Parker, Reiche y pH de abrasi6n). El proceso de meteorización dominante es la monosialitización, con una cierta tendencia bisialítica en las primeras fases de la alteración.[Abstract] A granite paleoweathering located under 120 m of tertiary sediments at Xinzo de Limia (Galicia, NW Spain) is studied. The transformation ofplagioclase in kaolinite is the most important mineralogical change ocurred during the process. Minor proportions of smectite- are detected too. The geochemistry study reveales an evident lixiviation of bases, so the different weathering rates decrease as the process progresses (Parker and Reiche indexes and abrasion-pH). The dominant process of weathering is the monosialitization (PEDRO, 1979) although the first phases show a bisialitic trend

    GeoCLEF 2007: the CLEF 2007 cross-language geographic information retrieval track overview

    Get PDF
    GeoCLEF ran as a regular track for the second time within the Cross Language Evaluation Forum (CLEF) 2007. The purpose of GeoCLEF is to test and evaluate cross-language geographic information retrieval (GIR): retrieval for topics with a geographic specification. GeoCLEF 2007 consisted of two sub tasks. A search task ran for the third time and a query classification task was organized for the first. For the GeoCLEF 2007 search task, twenty-five search topics were defined by the organizing groups for searching English, German, Portuguese and Spanish document collections. All topics were translated into English, Indonesian, Portuguese, Spanish and German. Several topics in 2007 were geographically challenging. Thirteen groups submitted 108 runs. The groups used a variety of approaches. For the classification task, a query log from a search engine was provided and the groups needed to identify the queries with a geographic scope and the geographic components within the local queries

    Data Mining: A Brief Introduction to the Field and Research Community

    Get PDF
    As organizations seek to understand and exploit vast – and increasing -- amounts of information brought by new technologies and practices, research in data mining and knowledge discovery is becoming increasing important. This paper presents a brief overview of the field of data mining, including research issues and information resources available through the research community

    GeoCLEF 2006: the CLEF 2006 Ccross-language geographic information retrieval track overview

    Get PDF
    After being a pilot track in 2005, GeoCLEF advanced to be a regular track within CLEF 2006. The purpose of GeoCLEF is to test and evaluate cross-language geographic information retrieval (GIR): retrieval for topics with a geographic specification. For GeoCLEF 2006, twenty-five search topics were defined by the organizing groups for searching English, German, Portuguese and Spanish document collections. Topics were translated into English, German, Portuguese, Spanish and Japanese. Several topics in 2006 were significantly more geographically challenging than in 2005. Seventeen groups submitted 149 runs (up from eleven groups and 117 runs in GeoCLEF 2005). The groups used a variety of approaches, including geographic bounding boxes, named entity extraction and external knowledge bases (geographic thesauri and ontologies and gazetteers)

    Challenges to evaluation of multilingual geographic information retrieval in GeoCLEF

    Get PDF
    This is the third year of the evaluation of geographic information retrieval (GeoCLEF) within the Cross-Language Evaluation Forum (CLEF). GeoCLEF 2006 presented topics and documents in four languages (English, German, Portuguese and Spanish). After two years of evaluation we are beginning to understand the challenges to both Geographic Information Retrieval from text and of evaluation of the results of geographic information retrieval. This poster enumerates some of these challenges to evaluation and comments on the limitations encountered in the first two evaluations

    Antioxidant vitamin intakes assessed using a food-frequency questionnaire: correlation with biochemical status in smokers and non-smokers

    Get PDF
    The increasing interest in the possible role of antioxidant vitamins in many disease states means that methods of assessing vitamin intakes which are suitable for large-scale investigations are now required. The suitability of the food-frequency questionnaire, which was developed by the Medical Research Council - Cardiff Group, for determining dietary intake of antioxidant vitamins in epidemiological studies was investigated in 196 Scottish men. The validity of the dietary data was assessed by comparison with serum vitamin concentrations, and separate analyses were performed for current smokers and non-smokers. The results showed that total energy intake and the percentage of energy derived from sugar were higher in smokers, and that both dietary and serum values of vitamin C, β-carotene and vitamin E were lower in smokers than non-smokers. After adjustment for serum lipids, energy intake and body mass index, correlation coefficients between dietary and serum vitamins C and E were similar for smokers (r 0.555 and 0.25 respectively) and non-smokers (r 0.58 and 0.32 respectively). Correlation between dietary and serum carotenes was reduced from 0.28 in non-smokers to 0.09 in smokers and correlations for retinol and total vitamin A were weakly significant only for non-smokers. The food-frequency questionnaire assigned > 70% of subjects correctly into the upper or lower plus adjacent tertiles of serum vitamin values, with the exception of β-carotene and total vitamin A for smokers. Thus, the food-frequency questionnaire appeared to be an adequate tool for assigning individuals into tertiles of serum antioxidant vitamins with the main exception of β-carotene for smokers. Marked differences do occur between the vitamins and between the smoking groups which may reflect reduced accuracy of reporting on the food-frequency questionnaire or differential absorption and metabolism of the vitamin
    corecore