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Search Results: 1 - 10 of 355621 matches for " Viviana E. Ré "
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Flexural Performance of I-Joist Fabricated with Glue-Laminated Bamboo and Gmelina arborea Plywood  [PDF]
Viviana Paniagua, Róger Moya
Open Journal of Civil Engineering (OJCE) , 2014, DOI: 10.4236/ojce.2014.43018
Abstract:

The search for efficient and versatile structural elements, leads to the fabrication of I-joists (6.5 cm × 18.5 cm × 600 cm (width × depth × length) with glue-laminated bamboo (Guada angustifolia) in the flanges and Gmelina arborea 12-mm structural plywood in the web. The results showed a modulus of rupture (MOR) of 39.45 MPa and an effective modulus of elasticity (MOE) of 17.05 GPa. Shearing in the glue line was 5.95 MPa and the lamination strength was 6.45 MPa. Structural design values averaged 9.43 MPa for bending and 4.72 MPa in shear according to Costa Rican structural standards. Both resistance value (flexure and shear) were considered satisfactory for structural proposes and I-joists fabricated with bamboo and G. arborea plywood are comparable with the Andean classification group “C” structural grade. The use of this I-joist was also shown in roofing and flooring systems. This beam can be used in allowable spans from 2 to 4 m in span for flooring systems and from 5 to 7 m for roofing applications.

New Withanolides from Two Varieties of Jaborosa Caulescens
Viviana E. Nicotra,Roberto R. Gil,Juan C. Oberti,Gerardo Burton
Molecules , 2000, DOI: 10.3390/50300514
Abstract: The phytochemical study of two species of Jaborosa caulescens (var. caulescens and var. bipinnatifida) yielded the four new withanolides 1-4. The structures of the new compounds were determined using a combination of spectroscopic techniques (including 1D and 2D NMR) and Molecular Modeling.
Determinación de la actividad celulolítica del suelo proveniente de cultivos de Stevia rebaudiana Bertoni
Gutiérrez R.,Viviana; Pinzón E.,ángela; Casas,Jaime; Martínez,María Mercedes;
Agronomía Colombiana , 2008,
Abstract: in this study celullolytic activity was determined in soil using a fluorogenic technique, which utilizes 4-methylumbelliferil b-glucose (muf) as substrate, and was compared with the quantitative technique of somogyi nelson (sn). sediment control was handled as a positive method of muf, as this technique was standardized previously in this matrix. soil sampling was done in puerto lópez, meta, in stevia rebaudiana bertoni crops using a simple random sampling. sediments were collected in la conejera wetland located in suba, bogotá. three treatments were done to both matrixes: t1: matrix (control); t2: matrix + crude enzymatic extract (2.34 uc); t3: matrix + streptomyces sp (59x103 spores/ml). to obtain the crude enzymatic extract used in t2 an isolation of the celulloytic microogranisms was done with greater activity in carboximethylcellulose (cmc 1%) from soil samples for its subsequent fermentation and extraction of enzyme extract. incubation of the matrix in three treatments was done at room temperature during 60 days where tests were performed every 15 days in order to analyze enzymatic activity by the established methods (muf and sn). humidity was maintained at 4.6%. no evidence of differential effects in the enzymatic activity with any of the treatments was found. also, there was no statistical correlation between the methods (<16%). thus, we propose the fluorogenic technique as a viable and reliable methodology to determinate cellulolytic activity because of its high specificity, faster assembly as well as its easy manipulation, precision and repeatability. nevertheless the sn technique has not been ruled out for future studies.
Detección molecular de enfermedad mínima residual en melanoma y otros tumores sólidos Molecular detection of minimal residual disease in melanoma and solid tumors
Valeria Vázquez,Laura L. Otero,Viviana E. Laurent,Mariano R. Gabri
Medicina (Buenos Aires) , 2009,
Abstract: La disponibilidad de métodos altamente sensibles y específicos para la detección de enfermedad mínima residual en pacientes con tumores sólidos podría tener importantes consecuencias pronósticas y terapéuticas. Uno de los métodos más usados para la detección molecular de células cancerosas es la técnica de RT-PCR, que permite la amplificación de secuencias de ARNm específicas de distintos tejidos. La misma fue aplicada por primera vez en la detección de células tumorales circulantes en sangre periférica de pacientes con melanoma avanzado, poco tiempo después fue adaptada para la búsqueda de enfermedad mínima residual en otros tumores sólidos. El objetivo de la presente revisión es evaluar la información publicada desde el primer estudio sobre este tema en 1991 y analizar el valor clínico de los hallazgos obtenidos. Se discute también la importancia del manejo de la muestra y de la estandarización de los procedimientos de RT-PCR. The availability of highly sensitive and specific methods for the detection of minimal residual disease in patients with solid tumors may have important prognostic and therapeutic implications. One of the most widely used methods for the molecular detection of cancer cells is the RT-PCR technique, which leads to the amplification of tissue-specific mRNA. It was firstly applied in the detection of circulating tumor cells in peripheral blood of patients with advanced melanoma; and soon it was adapted for the detection of minimal residual disease in other solid tumors. The aim of the present review is to evaluate the published data since the first study in 1991 and to analyze the clinical value of the findings obtained. The importance of sample handling and standardization of RT-PCR procedures is also discussed.
Determinación de la actividad celulolítica del suelo proveniente de cultivos de Stevia rebaudiana Bertoni
Gutiérrez R Viviana,Pinzón E. ángela,Casas Jaime,Martínez María Mercedes
Agronomía Colombiana , 2008,
Abstract: En el presente estudio se determinó la actividad celulolítica en suelo mediante el uso de una técnica fluorogénica que utiliza 4-metilumbeliferil B-glucosa (MUF) como sustrato, y se comparó con la técnica de Somogyi Nelson (SN). Se manejó sedimento como control positivo del método MUF, ya que esta técnica se estandarizó previamente en esta matriz, y suelo como matriz a evaluar. El muestreo de suelo se realizó en Puerto López, Meta, en cultivos de Stevia rebaudiana Bertoni mediante un muestreo aleatorio simple. El sedimento se recolectó en el humedal La Conejera, localidad de Suba, Bogotá. Se realizaron tres tratamientos para ambas matrices: T1: matriz (control); T2: matriz+extracto crudo enzimático (2,34 UC); T3: matriz+Streptomyces sp. (59x103 conidios/mL). Para la obtención del extracto crudo enzimático utilizado en el T2 se realizó el aislamiento del microorganismo celulolítico con mayor actividad en agar CMC 1% m/v a partir de muestras de suelo, para su posterior fermentación y obtención de extracto enzimático. La incubación de las matrices en los tres tratamientos se realizó a temperatura ambiente, humedad mantenida a 4,6% durante 60 días, con muestreos periódicos cada 15 días para determinar actividad enzimática por métodos planteados (MUF y SN). No se evidenciaron efectos diferenciales en la actividad enzimática con ninguno de los tratamientos planteados, como tampoco se obtuvo correlación estadística entre los métodos (<16%). Es así que se propone la técnica fluorogénica como una metodología viable y fiable de la actividad celulolítica, en virtud de su alta especificidad, mayor rapidez en el montaje, así como por su facilidad de ejecución y apreciable precisión en términos de repetibilidad; sin embargo la técnica de SN no se descarta para futuros estudios.
Detección molecular de enfermedad mínima residual en melanoma y otros tumores sólidos
Vázquez,Valeria; Otero,Laura L.; Laurent,Viviana E.; Gabri,Mariano R.; Gómez,Daniel E.; Alonso,Daniel F.;
Medicina (Buenos Aires) , 2009,
Abstract: the availability of highly sensitive and specific methods for the detection of minimal residual disease in patients with solid tumors may have important prognostic and therapeutic implications. one of the most widely used methods for the molecular detection of cancer cells is the rt-pcr technique, which leads to the amplification of tissue-specific mrna. it was firstly applied in the detection of circulating tumor cells in peripheral blood of patients with advanced melanoma; and soon it was adapted for the detection of minimal residual disease in other solid tumors. the aim of the present review is to evaluate the published data since the first study in 1991 and to analyze the clinical value of the findings obtained. the importance of sample handling and standardization of rt-pcr procedures is also discussed.
APOBEC3G Polymorphism as a Selective Barrier to Cross-Species Transmission and Emergence of Pathogenic SIV and AIDS in a Primate Host
Annabel Krupp,Kevin R. McCarthy,Marcel Ooms,Michael Letko,Jennifer S. Morgan,Viviana Simon,Welkin E. Johnson
PLOS Pathogens , 2013, DOI: 10.1371/journal.ppat.1003641
Abstract: Cellular restriction factors, which render cells intrinsically resistant to viruses, potentially impose genetic barriers to cross-species transmission and emergence of viral pathogens in nature. One such factor is APOBEC3G. To overcome APOBEC3G-mediated restriction, many lentiviruses encode Vif, a protein that targets APOBEC3G for degradation. As with many restriction factor genes, primate APOBEC3G displays strong signatures of positive selection. This is interpreted as evidence that the primate APOBEC3G locus reflects a long-term evolutionary “arms-race” between retroviruses and their primate hosts. Here, we provide direct evidence that APOBEC3G has functioned as a barrier to cross-species transmission, selecting for viral resistance during emergence of the AIDS-causing pathogen SIVmac in captive colonies of Asian macaques in the 1970s. Specifically, we found that rhesus macaques have multiple, functionally distinct APOBEC3G alleles, and that emergence of SIVmac and simian AIDS required adaptation of the virus to evade APOBEC3G-mediated restriction. Our evidence includes the first comparative analysis of APOBEC3G polymorphism and function in both a reservoir and recipient host species (sooty mangabeys and rhesus macaques, respectively), and identification of adaptations unique to Vif proteins of the SIVmac lineage that specifically antagonize rhesus APOBEC3G alleles. By demonstrating that interspecies variation in a known restriction factor selected for viral counter-adaptations in the context of a documented case of cross-species transmission, our results lend strong support to the evolutionary “arms-race” hypothesis. Importantly, our study confirms that APOBEC3G divergence can be a critical determinant of interspecies transmission and emergence of primate lentiviruses, including viruses with the potential to infect and spread in human populations.
Aves del Parque General San Martín (Mendoza): Distribución y características
Gómez,Viviana E.;
Multequina , 2006,
Abstract: birds of general san martín park (mendoza-argentina) were surveyed. their zones of action were defined, seasonal changes in composition and structure were analyzed, and observations on ecology and behaviour of birds were made. the work was carried out between january 2000 and january 2004. for the surveys, the 420 ha of the park were divided into 11 areas, called ornithological areas, according to the principal avenues and floristic differences. four areas were studied on a daily basis, staying for 30 minutes in each one during three days a week. behaviours, action areas, and daily and seasonal abundance were recorded. sixty-three bird species were recorded belonging to 25 families and 14 orders. passeriforms was the most representative order and tyrannidae the most diverse family. the highest daily abundance coincided with sunny days after a rain. the period of highest abundance coincided with the arrival of migratory species. the most diverse area was characterized by its variation in exotic and native plant species.
Estrategias mercantiles, redes y migraciones de comerciantes durante el período rosista
Conti,Viviana E.;
Cuadernos de la Facultad de Humanidades y Ciencias Sociales. Universidad Nacional de Jujuy , 2003,
Abstract: in argentine, the end of the independence wars was continued by the civil struggles. in the north west, they meant the local elites migration to the border countries after the federal triumph in 1831. this paper analyze the moves of the local merchants houses and the networks structure before the migrations. we also analyze these networks in valparaiso, cobija and potosì, between 1831 and 1852. this research is focused in the follow up about a little merchants group of salta and jujuy, along the 1st. half of nineteenth century. we select those who had to migrate by politics reasons.
Aves del parque general San Martín (Mendoza). Distribución y características
Viviana E. Gómez
Multequina , 2006,
Abstract: Se relevaron las aves del Parque General San Martín en Mendoza, Argentina; se definieron sus zonas de acción dentro del mismo, se analizaron los cambios estacionales en la composición y abundancia de especies y se efectuaron observaciones sobre la ecología y comportamiento de las aves que lo habitan. El trabajo se llevó a cabo entre enero de 2000 y enero de 2004. Para realizar los relevamientos se dividió el predio de 420 has en 11 áreas menores, denominadas áreas Ornitológicas, según las principales avenidas y las características florísticas. En general se recorrieron 4 áreas por día permaneciendo 30 minutos en cada una durante tres días por semana. Se observó comportamientos, áreas de acción, abundancia diaria y estacional en cada una. Se contabilizaron 63 especies de aves, pertenecientes a 25 familias y 14 órdenes. El orden más representado fue Passeriformes y la familia más diversa fue Tyrannidae. La mayor abundancia diaria coincidió con los días soleados posteriores a una lluvia. La época de mayor abundancia coincidió con la llegada de los migrantes de primavera. El área más diversa estuvo caracterizada por su variedad de vegetación exótica y nativa que atrae aves de ambientes áridos y otras típicas de ambientes más húmedos
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