159 research outputs found

    Towards automated composition of convergent services: a survey

    Get PDF
    A convergent service is defined as a service that exploits the convergence of communication networks and at the same time takes advantage of features of the Web. Nowadays, building up a convergent service is not trivial, because although there are significant approaches that aim to automate the service composition at different levels in the Web and Telecom domains, selecting the most appropriate approach for specific case studies is complex due to the big amount of involved information and the lack of technical considerations. Thus, in this paper, we identify the relevant phases for convergent service composition and explore the existing approaches and their associated technologies for automating each phase. For each technology, the maturity and results are analysed, as well as the elements that must be considered prior to their application in real scenarios. Furthermore, we provide research directions related to the convergent service composition phases

    Revalorización de la arquitectura vernácula: módulo de vivienda para una comunidad asháninka de Alto Kamonashiarii

    Get PDF
    DOI: https://doi.org/10.26439/limaq2021.n007.5185 The introduction of contemporary construction techniques and materials in native communities generates a distortion of their identity that affects the acceptance and use of local vernacular techniques. This article presents an experience that revalues ​​and analyzes vernacular architecture, obtained through the development of a housing module for an Ashaninka community in Alto Kamonashiarii in Satipo, carried out by the Sustainable Architecture Study Circle (CEAS) of the University of Lima.DOI: https://doi.org/10.26439/limaq2021.n007.5185 La introducción de técnicas constructivas o materiales contemporáneos en las comunidades nativas genera una distorsión de su identidad que repercute en la aceptación y empleo de las técnicas vernáculas locales. Este artículo presenta una experiencia que revaloriza y analiza la arquitectura vernácula, obtenida mediante el desarrollo de un módulo de vivienda para una comunidad asháninka de Alto Kamonashiarii, en Satipo, realizado por el Círculo de Estudio de Arquitectura Sostenible(CEAS) de la Universidad de Lima

    Selección de descriptores de tensión para localización de fallas en redes de distribución de energía

    Get PDF
    Permanent and transient power supply interruption affects power quality indexes related to continuity and causes negative effects in industry, commercial and residential users.As alternative to solve this problem,transmission networks have efficient fault location and protection schemes. Distribution facilities are constrained by technical,economical and operative aspects to implement fault identification and location strategies. In this paper an alternative solution of the fault location problem in power distribution systems, having a minimum of investment from utilities and giving appropriate information which helps to prevent and attend faults. By means of voltage signal characterization measured at the distribution substation and using an optimization and learning technique known as Support Vector Machines (SVM), the most probable zone where the fault was happened is located. The obtained results help to reduce time to locate faults in power distribution systems having a relatively low economical investment.La interrupción del suministro de energía eléctrica en forma permanente o transitoria, afectan los índices de calidad asociados con la continuidad y ocasionan efectos negativos en usuarios industriales, comerciales y residenciales. Para resolver este problema, las redes de transmisión cuentan con esquemas eficientes de protección y localización de fallas; las empresas de distribución, en razón de sus implicaciones técnicas, económicas y operativas,están limitadas para implementar estrategias de identificación y localización de fallas. En este artículo se presenta una alternativa de solución al problema de localización de fallas en redes de distribución de energía eléctrica, con un mínimo de inversión por parte de estas empresas y que proporcione la información apropiada para la prevención y atención oportuna de fallas. Mediante la caracterización de la señal de tensión medida en la subestación de distribución y utilizando la técnica de optimización y aprendizaje conocida como Máquinas de Soporte Vectorial (SVM), se localiza la zona probable donde ocurrió la falla.Los resultados obtenidos, permiten con muy bajo costo, mejorar los tiempos de localización de fallas en los sistemas de distribución

    Reduced mRNA abundance of the main enzymes involved in methionine metabolism in human liver cirrhosis and hepatocellular carcinoma

    Get PDF
    BACKGROUND/AIMS: It has been known for at least 50 years that alterations in methionine metabolism occur in human liver cirrhosis. However, the molecular basis of this alteration is not completely understood. In order to gain more insight into the mechanisms behind this condition, mRNA levels of methionine adenosyltransferase (MAT1A), glycine methyltransferase (GNMT), methionine synthase (MS), betaine homocysteine methyltransferase (BHMT) and cystathionine beta-synthase (CBS) were examined in 26 cirrhotic livers, five hepatocellular carcinoma (HCC) tissues and ten control livers. METHODS: The expression of the above-mentioned genes was determined by quantitative RT-PCR analysis. Methylation of MAT1A promoter was assessed by methylation-sensitive restriction enzyme digestion of genomic DNA. RESULTS: When compared to normal livers MAT1A, GNMT, BHMT, CBS and MS mRNA contents were significantly reduced in liver cirrhosis. Interestingly, MAT1A promoter was hypermethylated in the cirrhotic liver. HCC tissues also showed decreased mRNA levels of these enzymes. CONCLUSIONS: These findings establish that the abundance of the mRNA of the main genes involved in methionine metabolism is markedly reduced in human cirrhosis and HCC. Hypermethylation of MAT1A promoter could participate in its reduced expression in cirrhosis. These observations help to explain the hypermethioninemia, hyperhomocysteinemia and reduced hepatic glutathione content observed in cirrhosis

    Towards automated composition of convergent services: A survey

    Get PDF
    A convergent service is defined as a service that exploits the convergence of communication networks and at the same time takes advantage of features of the Web. Nowadays, building up a convergent service is not trivial, because although there are significant approaches that aim to automate the service composition at different levels in the Web and Telecom domains, selecting the most appropriate approach for specific case studies is complex due to the big amount of involved information and the lack of technical considerations. Thus, in this paper, we identify the relevant phases for convergent service composition and explore the existing approaches and their associated technologies for automating each phase. For each technology, the maturity and results are analysed, as well as the elements that must be considered prior to their application in real scenarios. Furthermore, we provide research directions related to the convergent service composition phases

    Parámetros genéticos de características de tipo y producción en ganado Holstein del departamento de Antioquia

    Get PDF
    RESUMEN Objetivo. Estimar heredabilidades, correlaciones fenotípicas y genotípicas entre 24 características de tipo y producción de leche en vacas Holstein del departamento de Antioquia. Materiales y métodos. Se analizaron un total de 2395 registros de vacas Holstein. Se estimaron componentes de varianza mediante el procedimiento de máxima verosimilitud restricta con modelos animales bi-característicos. Para las características de tipo, el modelo incluyó los efectos fijos de finca, año de nacimiento y país de origen del padre de la vaca, el grupo contemporáneo (año-mes-clasificador) y la covariable edad a la clasificación. Para la producción de leche el modelo incluyó los efectos fijos de finca, año de parto, país y año de nacimiento del padre. Resultados. Las heredabilidades encontradas para las características de tipo variaron de 0.04 a 0.44 y para producción de leche fue de 0.22, los errores estándar de la heredabilidad fueron inferiores a 0.06. Las correlaciones genéticas de producción de leche con las características profundidad de la ubre (-0.72) fue alta, mientras las correlaciones más altas entre las características de tipo fueron entre extremo anterior y tamaño (0.90), ángulo de la pezuña y profundidad del talón (0.98), profundidad del talón y uniformidad de pezuñas (0.85); y ligamento suspensorio medio y colocación de pezones posteriores (0.76). Conclusiónes. Se encontró una considerable variación genética en características de tipo dentro de la población Holstein de Antioquia. Las correlaciones genéticas entre algunas características de tipo fueron altas e indican la posibilidad de reducir el número de características evaluadas en cada anima

    Relación entre características de tipo y producción de leche en vacas Holstein de Antioquia, Colombia

    Get PDF
    Objetivo. Evaluar la relación entre las características de tipo agrupadas por factores con la producción de leche en ganado Holstein de Antioquia, Colombia. Materiales y métodos. Se utilizaron datos de 24 características lineales y producción de leche de 3102 vacas de la raza Holstein del departamento de Antioquia en control lechero oficial. Se realizó un análisis por factores (AF) con el método de componentes principales y se retuvieron los factores que mostraron valores propios mayores que 1.0. Posteriormente se realizó un análisis de varianza para la variable producción de leche, donde se tuvieron en cuenta los efectos fijos de finca, mes de parto y año de clasificación y se estimaron los coeficientes de regresión lineal para cada uno de los factores retenidos. Resultados. El AF mostró que sólo siete factores fueron retenidos y agruparon cerca del 64% del total de la varianza de todas las características de tipo analizadas. El primer factor reunió las variables relacionadas con la estructura general de la vaca y tuvo un valor propio de 3.85. El análisis de varianza mostró que los factores se relacionaron con producción de leche Conclusiones. Para producción de leche en Antioquia, Colombia, sobresalen las vacas grandes, anchas de pecho, altas y profundas del cuerpo, con pezuñas uniformes, angulosas y talones profundos, un sistema mamario caracterizado por ubres de textura suave, buen ligamento medio, un buen carácter lechero y ubres profundas

    Different doses of adenoviral vector expressing IL-12 enhance or depress the immune response to a coadministered antigen: the role of nitric oxide

    Get PDF
    Joint immunization with two recombinant adenoviruses, one expressing hepatitis C virus (HCV) core and E1 proteins and another expressing IL-12 (RAdIL-12), strongly potentiates cellular immune response against HCV Ags in BALB/c mice when RAdIL-12 was used at doses of 1 x 105-1 x 107 plaque-forming units. However, cellular immunity against HCV Ags was abolished when higher doses (1 x 108 plaque-forming units) of RAdIL-12 were used. This immunosuppressive effect was associated with marked elevation of IFN-gamma and nitric oxide in the serum and increased cell apoptosis in the spleen. Administration of N-nitro-L -arginine methyl ester (L-NAME), an inhibitor of nitric oxide synthase, to mice that received high doses of RAdIL-12 was lethal, whereas no apparent systemic toxicity by L -NAME was observed in those immunized with lower doses of the adenovirus. Interestingly, in mice immunized with recombinant adenovirus expressing core and E1 proteins of HCV in combination with RAdIL-12 at low doses (1 x 107 plaque-forming units), L -NAME inhibited T cell proliferation and CTL activity in response to HCV Ags and also production of Abs against adenoviral proteins. In conclusion, gene transfer of IL-12 can increase or abolish cell immunity against an Ag depending of the dose of the vector expressing the cytokine. IL-12 stimulates the synthesis of NO which is needed for the immunostimulating effects of IL-12, but apoptosis of T cells and immunosuppression ensues when IFN-gamma and NO are generated at very high concentrations

    Hyperhomocysteinemia in liver cirrhosis: mechanisms and role in vascular and hepatic fibrosis

    Get PDF
    Numerous clinical and epidemiological studies have identified elevated homocysteine levels in plasma as a risk factor for atherosclerotic vascular disease and thromboembolism. Hyperhomocysteinemia may develop as a consequence of defects in homocysteine-metabolizing genes; nutritional conditions leading to vitamin B(6), B(12), or folate deficiencies; or chronic alcohol consumption. Homocysteine is an intermediate in methionine metabolism, which takes place mainly in the liver. Impaired liver function leads to altered methionine and homocysteine metabolism; however, the molecular basis for such alterations is not completely understood. In addition, the mechanisms behind homocysteine-induced cellular toxicity are not fully defined. In the present work, we have examined the expression of the main enzymes involved in methionine and homocysteine metabolism, along with the plasma levels of methionine and homocysteine, in the liver of 26 cirrhotic patients and 10 control subjects. To gain more insight into the cellular effects of elevated homocysteine levels, we have searched for changes in gene expression induced by this amino acid in cultured human vascular smooth muscle cells. We have observed a marked reduction in the expression of the main genes involved in homocysteine metabolism in liver cirrhosis. In addition, we have identified the tissue inhibitor of metalloproteinases-1 and alpha1(I)procollagen to be upregulated in vascular smooth muscle cells and liver stellate cells exposed to pathological concentrations of homocysteine. Taken together, our observations suggest (1) impaired liver function could be a novel determinant in the development of hyperhomocysteinemia and (2) a role for elevated homocysteine levels in the development of liver fibrosis

    Methylthioadenosine phosphorylase gene expression is impaired in human liver cirrhosis and hepatocarcinoma

    Get PDF
    Methylthioadenosine phosphorylase (MTAP) is a key enzyme in the methionine and adenine salvage pathways. In mammals, the liver plays a central role in methionine metabolism, and this essential function is lost in the progression from liver cirrhosis to hepatocarcinoma. Deficient MTAP gene expression has been recognized in many transformed cell lines and tissues. In the present work, we have studied the expression of MTAP in human and experimental liver cirrhosis and hepatocarcinoma. We observe that MTAP gene expression is significantly reduced in human hepatocarcinoma tissues and cell lines. Interestingly, MTAP gene expression was also impaired in the liver of CCl4-cirrhotic rats and cirrhotic patients. We provide evidence indicating that epigenetic mechanisms, involving DNA methylation and histone deacetylation, may play a role in the silencing of MTAP gene expression in hepatocarcinoma. Given the recently proposed tumor suppressor activity of MTAP, our observations can be relevant to the elucidation of the molecular mechanisms of multistep hepatocarcinogenesis
    corecore