1,742 research outputs found

    Characterization of ISP Traffic: Trends, User Habits, and Access Technology Impact

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    In the recent years, the research community has increased its focus on network monitoring which is seen as a key tool to understand the Internet and the Internet users. Several studies have presented a deep characterization of a particular application, or a particular network, considering the point of view of either the ISP, or the Internet user. In this paper, we take a different perspective. We focus on three European countries where we have been collecting traffic for more than a year and a half through 5 vantage points with different access technologies. This humongous amount of information allows us not only to provide precise, multiple, and quantitative measurements of "What the user do with the Internet" in each country but also to identify common/uncommon patterns and habits across different countries and nations. Considering different time scales, we start presenting the trend of application popularity; then we focus our attention to a one-month long period, and further drill into a typical daily characterization of users activity. Results depict an evolving scenario due to the consolidation of new services as Video Streaming and File Hosting and to the adoption of new P2P technologies. Despite the heterogeneity of the users, some common tendencies emerge that can be leveraged by the ISPs to improve their servic

    Amplification and cloning of cDNAS of cytochrome P4501A1 and metallothionein genes from Sparus aurata Linnaeus, 1758 and Liza aurata (Risso, 1810) by Race-PCR

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    The biotransformation of xenobiotics found in marine ecosystems is catalysed by inducible systems, a property that makes them useful as early-warning biomarkers of environmental pollution. We have focused our study on cytochrome P4501A1 (CYP 1A1) as a phase I response against organic aromatic xenobiotics, and metallothionein (MT), which reflects pollution by transition metals. The high homology existing between the sequences of both genes, already cloned in different fish species, enabled us to design degenerate oligos to amplify by RT-PCR specific sequences of CYP 1A1 and MT genes in two teleost fish species of the Spanish South Atlantic littoral, the gilthead seabream, Sparus aurata Linnaeus, 1758, and the grey mullet, Liza aurata (Risso 1810). To this end, the expression of both genes was previously induced by intraperitoneal injection with Aroclor 1254 (CYP 1A1) and CdCl2 (MT). The specific sequences for both genes amplified by RT-PCR with degenerate oligos were subsequently used to design new, specific oligos to obtain by Race-PCR (Rapid Amplification of cDNA Ends) the complete cDNAs coding for both genes in both fish species, which were subsequently cloned and sequenced. The coding sequences and the corresponding proteins were compared with those already obtained in other fish species. We are currently developing homologous probes for mRNA quantification using molecular biology techniques in both fish species, to be employed as molecular biomarkers of pollution in the Spanish South Atlantic littoral.La biotransformación de xenobióticos presentes en ecosistemas marinos está catalizada por varios sistemas inducibles, lo que permite su uso como biomarcadores de alerta temprana de contaminación ambiental. Este estudio se ha centrado en el citocromo P4501A1 (CYP 1A1), como respuesta de fase I contra xenobióticos orgánicos aromáticos, y la metalotioneína (MT), que refleja la contaminación por metales de transición. La alta homología existente entre las secuencias de ambos genes previamente clonados en diferentes especies de peces permitió diseñar oligos degenerados para amplificar por RT-PCR secuencias específicas de los genes CYP 1A1 y MT en dos especies de peces teleósteos del litoral suratlántico español, la dorada Sparus aurata Linnaeus, 1758 y la lisa Liza aurata (Risso, 1810). Para ello, la expresión de ambos genes se indujo por inyección intraperitoneal con Aroclor 1254 (CYP 1A1) y CdCl2 (MT). Las secuencias específicas de ambos genes, amplificadas por RT-PCR con tales oligos, se usaron posteriormente para diseñar nuevos oligos específicos; éstos se usaron para amplificar por Race-PCR (Rapid Amplification of cDNA Ends) los cDNAs completos que codifican tales genes en ambas especies de peces, que fueron posteriormente clonados y secuenciados. Las secuencias codificantes y las proteínas correspondientes se han comparado con las obtenidas en otras especies de peces. Actualmente se desarrollan sondas homólogas para cuantificar por métodos de biología molecular los mRNAs específicos en ambos peces, para su uso como biomarcadores moleculares de contaminación en el litoral suratlántico español.Instituto Español de Oceanografí

    Charles Tilly: Legado y estela De The Vendée a Contentious Performances, para comprender el conflicto político del s. XIX español

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    Charles Tilly’s later work sums up, assesses, specifies and projects into the future the theoretical and empirical legacy of a life of study devoted to Historical Sociology. From his masterpiece opera prima, The Vendée, on to his latest Contentious politics, Tilly developed a vast array of theoretical concepts, which he provided with extensive and precise empirical referents (among them, we may cite: performance, collective action repertoire, political opportunity structure, mechanisms for mobilization and, finally, worthiness, unity, numbers and commitment). Today, these notions are located at the very core of the sociological/historical studies about political contention in early Modern Europe. Tilly’s preference for quantitative and comparative methods was subservient to his interest in giving account of, not the motivational Why?, but the objective How, When and What for of collective mobilization; not in explanatory ‘laws’ of historical change, but in analytically fecund descriptions of similar, but also unique historical episodes. This article adopts the methodological paradigm Tilly first developed when writing The Vendée, analytically updated throughout his later work, as theoretical framework for a new approach of the social and political mobilization that led to the first Carlista war. Specifically, the mechanisms for mobilization that provided material and human resources for the war effort are researched in three different Navarre villages –selected by their differing economic, cultural, and politically features.Las últimas obras de Charles Tilly recapitulan, evalúan, concretan y proyectan hacia el futuro el legado empírico y teórico de una vida dedicada a la sociología histórica. Desde su opera prima sobre la Vendée hasta Contienda política y democracia en Europa, Tilly desarrolló y dio amplio y preciso contenido empírico a un conjunto de conceptos teóricos que hoy vertebran los estudios del conflicto político al inicio de la modernidad europea (entre otros, actuación, repertorio de acción colectiva, estructura de oportunidad política, mecanismos de movilización y, finalmente el despliegue de respetabilidad, unidad, número y compromiso ‒WUNC, en su acrónimo inglés). Su predilección por los métodos cuantitativos y comparativos perseguía explicar, no el motivacional por qué sino el objetivo cómo, cuándo y para qué de la movilización popular; no buscaba ‘leyes’ del cambio histórico, sino descripciones analíticamente fértiles de acontecimientos históricos semejantes, pero singulares y únicos. El paradigma metodológico que elaboró por vez primera en La Vendeé, analíticamente actualizado a través de su obra posterior, sirve aquí como marco para un nuevo abordaje de la movilización social y política que condujo a la primera guerra carlista, específicamente, mediante el estudio comparado de los mecanismos de movilización de recursos materiales y humanos para el esfuerzo de guerra en tres municipios navarros de características económicas, culturales y políticas bien diferenciadas

    Amplification and cloning of cDNAS of cytochrome P4501A1 and metallothionein genes from Sparus aurata Linnaeus, 1758 and Liza aurata (Risso, 1810) by Race-PCR

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    The biotransformation of xenobiotics found in marine ecosystems is catalysed by inducible systems, a property that makes them useful as early-warning biomarkers of environmental pollution. We have focused our study on cytochrome P4501A1 (CYP 1A1) as a phase I response against organic aromatic xenobiotics, and metallothionein (MT), which reflects pollution by transition metals. The high homology existing between the sequences of both genes, already cloned in different fish species, enabled us to design degenerate oligos to amplify by RT-PCR specific sequences of CYP 1A1 and MT genes in two teleost fish species of the Spanish South Atlantic littoral, the gilthead seabream, Sparus aurata Linnaeus, 1758, and the grey mullet, Liza aurata (Risso 1810). To this end, the expression of both genes was previously induced by intraperitoneal injection with Aroclor 1254 (CYP 1A1) and CdCl2 (MT). The specific sequences for both genes amplified by RT-PCR with degenerate oligos were subsequently used to design new, specific oligos to obtain by Race-PCR (Rapid Amplification of cDNA Ends) the complete cDNAs coding for both genes in both fish species, which were subsequently cloned and sequenced. The coding sequences and the corresponding proteins were compared with those already obtained in other fish species. We are currently developing homologous probes for mRNA quantification using molecular biology techniques in both fish species, to be employed as molecular biomarkers of pollution in the Spanish South Atlantic littoralLa biotransformación de xenobióticos presentes en ecosistemas marinos está catalizada por varios sistemas inducibles, lo que permite su uso como biomarcadores de alerta temprana de contaminación ambiental. Este estudio se ha centrado en el citocromo P4501A1 (CYP 1A1), como respuesta de fase I contra xenobióticos orgánicos aromáticos, y la metalotioneína (MT), que refleja la contaminación por metales de transición. La alta homología existente entre las secuencias de ambos genes previamente clonados en diferentes especies de peces permitió diseñar oligos degenerados para amplificar por RT-PCR secuencias específicas de los genes CYP 1A1 y MT en dos especies de peces teleósteos del litoral suratlántico español, la dorada Sparus aurata Linnaeus, 1758 y la lisa Liza aurata (Risso, 1810). Para ello, la expresión de ambos genes se indujo por inyección intraperitoneal con Aroclor 1254 (CYP 1A1) y CdCl2 (MT). Las secuencias específicas de ambos genes, amplificadas por RT-PCR con tales oligos, se usaron posteriormente para diseñar nuevos oligos específicos; éstos se usaron para amplificar por Race-PCR (Rapid Amplification of cDNA Ends) los cDNAs completos que codifican tales genes en ambas especies de peces, que fueron posteriormente clonados y secuenciados. Las secuencias codificantes y las proteínas correspondientes se han comparado con las obtenidas en otras especies de peces. Actualmente se desarrollan sondas homólogas para cuantificar por métodos de biología molecular los mRNAs específicos en ambos peces, para su uso como biomarcadores moleculares de contaminación en el litoral suratlántico españo

    Utilização de dados TM-LANDSAT para o mapeamento e monitoramento da cobertura vegetal.

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    Apesar da área florestada de cerca de 4 milhões de km2, a situação da Região Amazônica é preocupante em função do crescente processo de ocupação representado pela colonização agrícola e abertura de novas zonas rurais. A fim de identificar estas alterações na vegetação natural, este trabalho realizou o mapeamento e monitoramento espaço-temporal de uma área da Amazônia Legal, no Estado do Mato Grosso, através da Amazônia Legal, no Estado do Mato Grosso, através da metodologia desenvolvida no âmbito do Projeto TREES e também incorporando e testando a utilização do Índice de Vegetação da Diferença Normalizada (IVDN). Foram classificadas duas imagens TM-LANDSAT (1992 e 1997) e realizada a tabulação cruzada entre as mesmas para quantificar e identificar os processos antrópicos entre estas duas datas. Verificou-se que grandes propriedades, abundantes em 1992, foram mascaradas pelo excesso de nuvens em 1997. Os IVDN obtidos para cada uma das classes de vegetação (floresta, mosaico e cerrado) foram condizentes com o esperado, onde as classes com maior densidade arbórea apresentaram os maiores valores do índice

    Synthesis of hydroxyfatty esters by sequential epoxidation-hydrogenolysis: Solvent effects

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    The tandem/sequential combination of epoxidation and hydrogenolysis for unsaturated fatty esters is not straightforward, due to incompatibility problems with the impurities present or generated in the used solvents. The chlorinated impurities in alpha, alpha, alpha-trifluorotoluene leads to the formation of important amounts of chlorohydrins by HCl formation in the hydrogenolysis step. The use of trifluoroethanol (TFE) in the epoxidation step produces trifluoroacetic acid traces by oxidation, responsible for the opening of the epoxide with water and TFE. The solvent of choice was finally isobutyl acetate, which gathers the required physicochemical properties, with 85 % yield of hydroxystearates from methyl oleate in a sequential process
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