927 research outputs found

    Characterisation of abrasive water-jet process for drilling titanium and carbon fibre reinforced polymer stacks

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    Experiments were carried out in stacks composed of titanium and carbon-fibre-reinforced polymer (CFRP) with the aim to investigate the effect of water-jet process variables on drilled diameter and surface condition. A design of experiments (DoE) approach was taken, considering variables such as water pressure, traverse rate, abrasive mass flow and stack set-up. Two different set-ups were investigated: CFRP over titanium (CFRP/Ti) and vice versa (Ti/CFRP). The experimental variables were related to taper ratio, surface roughness of the hole bore, hole quality and surface condition. Statistical analysis was carried out in order to develop mathematical models which include process variables interactions and quadratic terms. This led to models with high correlation and prediction power; which allow a better understanding of the process and can form the base for further process optimisation. The models were validated with additional experiments and showed good agreement with the water-jet system. The results showed that set-up and its interaction with other process variables has a strong influence on the performance of the abrasive water-jet system for producing holes in hybrid materials

    Bioprospección de hiperparásitos de Hemileia vastatrix en Guatemala

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    La bioprospección de agentes de control biológico es una actividad primaria en la búsqueda de alternativas para el manejo de plagas y enfermedades; las reservas naturales dentro de plantaciones de café por las caracterí­sticas de biodiversidad son aptas para albergar diversidad microbiana y entre ellos agentes biocontroladores. El estudio se realizó en 10 fincas con reservas naturales con café, cinco en el departamento de Guatemala, cuatro en Sacatepéquez y una en Chimaltenango, los muestreos se realizaron en época seca y lluviosa; se obtuvo, documentó y determinaron en laboratorio los agentes hiperparásitos: Cladosporium hemileiae Steyaert, y Lecanicillium lecanii (Zimmerm.) Zare & W. Gams y además un insecto micófago Mycodiplosis sp. (Diptera, Cecidomyiidae). Se evaluaron las cepas de los hongos hiperparásitos con el í­ndice de velocidad de crecimiento micelial (IVCM) y producción de conidiosporas. Se estableció que las mejores cepas de C. hemileiae fueron: Morán época seca parte baja, San Sebastián época seca y Guardabarranca parte alta; para L. lecanii fueron: San Sebastián época seca y Corral Viejo estación lluviosa parte baja

    Effect of five rootstocks in flowering, fructification and maturity in orange "frost valencia" citrus sinensis (l.) obs. in palmira, the cauca valley

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    The work was made at Instituto Colombiano Agropecuario, Palmira in the Cauca Valley. It was considered under observation twenty citric trees over five rootstocks: Citrumelo 4475, Citrus amblycarpa, Citrange yuma, Trifoliado por Ruby Or and Mandarina Cleopatra. Flower development, intensity of flower and fruit production, thicken percentage, fruit's development, fruits falled percentage, maduration process and number and weight at harvested fruits was evaluated. Flowering is induced between 15-30 days after any rain. The maximum fruit production was between five and six months after maximum precipitation. The rootstocks are different in maturity epoch, fruit's production; however there were not great differences in potential production (17-20%).En el trabajo, realizado en el Instituto Colombiano Agropecuario en Palmira, Valle del Cauca, se consideraron 20 árboles cítricos injertados sobre Citrumelo 4475, Citrus amblycarpa, Citrange yuma, Trifoliado por Ruby Or y Mandarina Cleopatra. Se evaluaron los parámetros desarrollo floral, época e intensidad de la floración, porcentaje de cuajamiento, desarrollo del fruto, proceso de maduración y número y peso de frutos cosechados. La floración de la naranja ocurrió 15-30 días después de una lluvia; la máxima producción de frutos se presentó entre cinco y seis meses después de la máxima precipitación. Los porta-injertos mostraron diferenciase significativas en período de maduración y producción de frutos; no obstante, su potencial productivo fue relativamente similar (17-20%)

    Morphometrics and Phylogenomics of Coca ( Erythroxylum spp.) Illuminate Its Reticulate Evolution, With Implications for Taxonomy

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    South American coca (Erythroxylum coca and E. novogranatense) has been a keystone crop for many Andean and Amazonian communities for at least 8,000 years. However, over the last half-century, global demand for its alkaloid cocaine has driven intensive agriculture of this plant and placed it in the center of armed conflict and deforestation. To monitor the changing landscape of coca plantations, the United Nations Office on Drugs and Crime collects annual data on their areas of cultivation. However, attempts to delineate areas in which different varieties are grown have failed due to limitations around identification. In the absence of flowers, identification relies on leaf morphology, yet the extent to which this is reflected in taxonomy is uncertain. Here, we analyze the consistency of the current naming system of coca and its four closest wild relatives (the “coca clade”), using morphometrics, phylogenomics, molecular clocks, and population genomics. We include name-bearing type specimens of coca's closest wild relatives E. gracilipes and E. cataractarum. Morphometrics of 342 digitized herbarium specimens show that leaf shape and size fail to reliably discriminate between species and varieties. However, the statistical analyses illuminate that rounder and more obovate leaves of certain varieties could be associated with the subtle domestication syndrome of coca. Our phylogenomic data indicate extensive gene flow involving E. gracilipes which, combined with morphometrics, supports E. gracilipes being retained as a single species. Establishing a robust evolutionary-taxonomic framework for the coca clade will facilitate the development of cost-effective genotyping methods to support reliable identification

    Ethylene is involved in strawberry fruit ripening in an organ-specific manner

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    The fruit of the strawberry Fragaria×ananassa has traditionally been classified as non-climacteric because its ripening process is not governed by ethylene. However, previous studies have reported the timely endogenous production of minor amounts of ethylene by the fruit as well as the differential expression of genes of the ethylene synthesis, reception, and signalling pathways during fruit development. Mining of the Fragaria vesca genome allowed for the identification of the two main ethylene biosynthetic genes, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase. Their expression pattern during fruit ripening was found to be stage and organ (achene or receptacle) specific. Strawberry plants with altered sensitivity to ethylene could be employed to unravel the role of ethylene in the ripening process of the strawberry fruit. To this end, independent lines of transgenic strawberry plants were generated that overexpress the Arabidopsis etr1-1 mutant ethylene receptor, which is a dominant negative allele, causing diminished sensitivity to ethylene. Genes involved in ethylene perception as well as in its related downstream processes, such as flavonoid biosynthesis, pectin metabolism, and volatile biosynthesis, were differently expressed in two transgenic tissues, the achene and the receptacle. The different transcriptional responsiveness of the achene and the receptacle to ethylene was also revealed by the metabolic profiling of the primary metabolites in these two organs. The free amino acid content was higher in the transgenic lines compared with the control in the mature achene, while glucose and fructose, and citric and malic acids were at lower levels. In the receptacle, the most conspicuous change in the transgenic lines was the depletion of the tricarboxylic acid cycle intermediates at the white stage of development, most probably as a consequence of diminished respiration. The results are discussed in the context of the importance of ethylene during strawberry fruit ripening.Facultad de Ciencias ExactasInstituto de Fisiología Vegeta

    Resultados preliminares de la evaluación de vacunas oleosas contra la fiebre aftosa en Colombia.

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    En el presente trabajo se reportan los resultados preliminares de evaluación de vacunas con adyuvante oleoso en bovinos inoculados previamente con vacunas hidroxisaponinadas. Se utilizó una vacuna elaborada en el Laboratorio de Enfermedades Animales de Plum Island con cepas colombianas preparadas en células BHK21, cultivadas en botellas rotantes e inactivadas con ethylene imina binaria (BEI). El adyuvante fué preparado con aceite mineral (markol 52) y arlacel A. La dosis fué de 5 ml de vacuna bivalente administrada por vía subcutánea. El experimento se realizó en una hacienda de tipo comercial, con condición de bosque tropical húmedo, a una altitud de 0 m.s.n.m. y una temperatura promedio de 28 grados centígrados. Se vacunaron 1000 bovinos, de los cuales 391 correspondieron a animales menores de dos años y los restantes a adultos. El esquema de vacunación de la primera dosis se estableció sin considerar edad y número de vacunaciones anteriores realizadas con vacuna hidroxisaponinada y con base a niveles de anticuerpos se seleccionaron grupos de jóvenes y adultos. La respuesta inmunitaria fué determinada por evaluación de niveles de anticuerpos neutralizantes, a los 4, 6, 8 y 12 meses post-vacunación. El número de muestras para cada sangría se estableció por métodos estadísticos. Los altos niveles de anticuerpos observados a 4, 6, 8 y 12 meses en los dos grupos de animales que recibieron vacuna oleosa indican que se puede lograr una inmunidad uniforme y duradera con una o dos aplicaciones de vacuna oleosa al año En los animales vacunados no se presentó ninguna reacción indeseable y los nódulos vacunales desaparecieron entre 1 y 2 mesesGanado de doble propósito-Ganaderia doble proposit

    Ethylene is involved in strawberry fruit ripening in an organ-specific manner

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    The fruit of the strawberry Fragaria×ananassa has traditionally been classified as non-climacteric because its ripening process is not governed by ethylene. However, previous studies have reported the timely endogenous production of minor amounts of ethylene by the fruit as well as the differential expression of genes of the ethylene synthesis, reception, and signalling pathways during fruit development. Mining of the Fragaria vesca genome allowed for the identification of the two main ethylene biosynthetic genes, 1-aminocyclopropane-1-carboxylic acid (ACC) synthase and ACC oxidase. Their expression pattern during fruit ripening was found to be stage and organ (achene or receptacle) specific. Strawberry plants with altered sensitivity to ethylene could be employed to unravel the role of ethylene in the ripening process of the strawberry fruit. To this end, independent lines of transgenic strawberry plants were generated that overexpress the Arabidopsis etr1-1 mutant ethylene receptor, which is a dominant negative allele, causing diminished sensitivity to ethylene. Genes involved in ethylene perception as well as in its related downstream processes, such as flavonoid biosynthesis, pectin metabolism, and volatile biosynthesis, were differently expressed in two transgenic tissues, the achene and the receptacle. The different transcriptional responsiveness of the achene and the receptacle to ethylene was also revealed by the metabolic profiling of the primary metabolites in these two organs. The free amino acid content was higher in the transgenic lines compared with the control in the mature achene, while glucose and fructose, and citric and malic acids were at lower levels. In the receptacle, the most conspicuous change in the transgenic lines was the depletion of the tricarboxylic acid cycle intermediates at the white stage of development, most probably as a consequence of diminished respiration. The results are discussed in the context of the importance of ethylene during strawberry fruit ripening.Facultad de Ciencias ExactasInstituto de Fisiología Vegeta

    National Prevalence and Trends of HIV Transmitted Drug Resistance in Mexico

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    BACKGROUND: Transmitted drug resistance (TDR) remains an important concern for the management of HIV infection, especially in countries that have recently scaled-up antiretroviral treatment (ART) access. METHODOLOGY/PRINCIPAL FINDINGS: We designed a study to assess HIV diversity and transmitted drug resistance (TDR) prevalence and trends in Mexico. 1655 ART-naïve patients from 12 Mexican states were enrolled from 2005 to 2010. TDR was assessed from plasma HIV pol sequences using Stanford scores and the WHO TDR surveillance mutation list. TDR prevalence fluctuations over back-projected dates of infection were tested. HIV subtype B was highly prevalent in Mexico (99.9%). TDR prevalence (Stanford score>15) in the country for the study period was 7.4% (95% CI, 6.2∶8.8) and 6.8% (95% CI, 5.7∶8.2) based on the WHO TDR surveillance mutation list. NRTI TDR was the highest (4.2%), followed by NNRTI (2.5%) and PI (1.7%) TDR. Increasing trends for NNRTI (p = 0.0456) and PI (p = 0.0061) major TDR mutations were observed at the national level. Clustering of viruses containing minor TDR mutations was observed with some apparent transmission pairs and geographical effects. CONCLUSIONS: TDR prevalence in Mexico remains at the intermediate level and is slightly lower than that observed in industrialized countries. Whether regional variations in TDR trends are associated with differences in antiretroviral drug usage/ART efficacy or with local features of viral evolution remains to be further addressed

    The Long-Baseline Neutrino Experiment: Exploring Fundamental Symmetries of the Universe

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    The preponderance of matter over antimatter in the early Universe, the dynamics of the supernova bursts that produced the heavy elements necessary for life and whether protons eventually decay --- these mysteries at the forefront of particle physics and astrophysics are key to understanding the early evolution of our Universe, its current state and its eventual fate. The Long-Baseline Neutrino Experiment (LBNE) represents an extensively developed plan for a world-class experiment dedicated to addressing these questions. LBNE is conceived around three central components: (1) a new, high-intensity neutrino source generated from a megawatt-class proton accelerator at Fermi National Accelerator Laboratory, (2) a near neutrino detector just downstream of the source, and (3) a massive liquid argon time-projection chamber deployed as a far detector deep underground at the Sanford Underground Research Facility. This facility, located at the site of the former Homestake Mine in Lead, South Dakota, is approximately 1,300 km from the neutrino source at Fermilab -- a distance (baseline) that delivers optimal sensitivity to neutrino charge-parity symmetry violation and mass ordering effects. This ambitious yet cost-effective design incorporates scalability and flexibility and can accommodate a variety of upgrades and contributions. With its exceptional combination of experimental configuration, technical capabilities, and potential for transformative discoveries, LBNE promises to be a vital facility for the field of particle physics worldwide, providing physicists from around the globe with opportunities to collaborate in a twenty to thirty year program of exciting science. In this document we provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess.Comment: Major update of previous version. This is the reference document for LBNE science program and current status. Chapters 1, 3, and 9 provide a comprehensive overview of LBNE's scientific objectives, its place in the landscape of neutrino physics worldwide, the technologies it will incorporate and the capabilities it will possess. 288 pages, 116 figure
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