190 research outputs found

    First collection of landrace vegetable crops cultivated in Valle Fértil, Argentina

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    The richness of the cultural values found in the Argentinean Andean communities is integrated by a varied diversity of genetic resources, the development of a sustainable agriculture, and the conservation of the producer’s own seeds. Local agriculture is a family economic activity, in which traditional varieties of vegetable landraces are highly appreciated for their flavour, colour and aromas. However; social, economic and environmental factors have an effect on crop diversity conservation. The main aim of this work was to retrieve and maintain a representative collection of traditional crop genetic resources still cultivated in the District of Valle Fértil, San Juan Province, Argentina, and to document the farmers’ crop experiences and uses. Fifty families were interviewed; 26 of these donated a total of 49 samples belonging to eight species. The landraces collected showed a geometric distribution, typical of communities with low number of species; and a pattern of dominance. A few species are present in almost all farms while rare species are found in specific environments. Local germplasm recovery can prevent genetic erosion, so that both the formal breeding sector and the farmers can make use of the diversity of this collection.La riqueza cultural de las comunidades andinas de la Argentina está integrada por la diversidad de sus recursos genéticos, el desarrollo de un sistema agrícola sostenible y por el mantenimiento de sus semillas. La agricultura local es una actividad económica familiar, donde las variedades tradicionales de hortalizas son muy apreciadas por su sabor, color y aroma. Sin embargo, distintos factores sociales, económicos y ambientales afectan la diversidad de tales cultivos. Los objetivos de este trabajo fueron recuperar y conservar una muestra representativa de los recursos genéticos vegetales tradicionales aún presentes en el departamento de Valle Fértil, provincia de San Juan, Argentina, y documentar las experiencias y usos de ellos por parte de los productores. Se entrevistaron 50 familias de las cuales 26 donaron un total de 49 muestras pertenecientes a ocho especies. Las variedades criollas recolectadas mostraron una distribución geométrica típica en comunidades con pocasespecies, y un patrón de dominancia donde algunas especies están presentes en casi todas las huertas mientras que especies poco representadas se encuentran en ambientes específicos. La recuperación del germoplasma local puede prevenir la erosión genética, de modo que tanto los mejoradores como los productores puedan aprovechar la diversidad de esta colección

    Search for composite and exotic fermions at LEP 2

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    A search for unstable heavy fermions with the DELPHI detector at LEP is reported. Sequential and non-canonical leptons, as well as excited leptons and quarks, are considered. The data analysed correspond to an integrated luminosity of about 48 pb^{-1} at an e^+e^- centre-of-mass energy of 183 GeV and about 20 pb^{-1} equally shared between the centre-of-mass energies of 172 GeV and 161 GeV. The search for pair-produced new leptons establishes 95% confidence level mass limits in the region between 70 GeV/c^2 and 90 GeV/c^2, depending on the channel. The search for singly produced excited leptons and quarks establishes upper limits on the ratio of the coupling of the excited fermio

    Search for charginos in e+e- interactions at sqrt(s) = 189 GeV

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    An update of the searches for charginos and gravitinos is presented, based on a data sample corresponding to the 158 pb^{-1} recorded by the DELPHI detector in 1998, at a centre-of-mass energy of 189 GeV. No evidence for a signal was found. The lower mass limits are 4-5 GeV/c^2 higher than those obtained at a centre-of-mass energy of 183 GeV. The (\mu,M_2) MSSM domain excluded by combining the chargino searches with neutralino searches at the Z resonance implies a limit on the mass of the lightest neutralino which, for a heavy sneutrino, is constrained to be above 31.0 GeV/c^2 for tan(beta) \geq 1.Comment: 22 pages, 8 figure

    Search for lightest neutralino and stau pair production in light gravitino scenarios with stau NLSP

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    Promptly decaying lightest neutralinos and long-lived staus are searched for in the context of light gravitino scenarios. It is assumed that the stau is the next to lightest supersymmetric particle (NLSP) and that the lightest neutralino is the next to NLSP (NNLSP). Data collected with the Delphi detector at centre-of-mass energies from 161 to 183 \GeV are analysed. No evidence of the production of these particles is found. Hence, lower mass limits for both kinds of particles are set at 95% C.L.. The mass of gaugino-like neutralinos is found to be greater than 71.5 GeV/c^2. In the search for long-lived stau, masses less than 70.0 to 77.5 \GeVcc are excluded for gravitino masses from 10 to 150 \eVcc . Combining this search with the searches for stable heavy leptons and Minimal Supersymmetric Standard Model staus a lower limit of 68.5 \GeVcc may be set for the stau mas

    Hadronization properties of b quarks compared to light quarks in e+e- -> q qbar from 183 to 200 GeV

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    The DELPHI detector at LEP has collected 54 pb^{-1} of data at a centre-of-mass energy around 183 GeV during 1997, 158 pb^{-1} around 189 GeV during 1998, and 187 pb^{-1} between 192 and 200 GeV during 1999. These data were used to measure the average charged particle multiplicity in e+e- -> b bbar events, _{bb}, and the difference delta_{bl} between _{bb} and the multiplicity, _{ll}, in generic light quark (u,d,s) events: delta_{bl}(183 GeV) = 4.55 +/- 1.31 (stat) +/- 0.73 (syst) delta_{bl}(189 GeV) = 4.43 +/- 0.85 (stat) +/- 0.61 (syst) delta_{bl}(200 GeV) = 3.39 +/- 0.89 (stat) +/- 1.01 (syst). This result is consistent with QCD predictions, while it is inconsistent with calculations assuming that the multiplicity accompanying the decay of a heavy quark is independent of the mass of the quark itself.Comment: 13 pages, 2 figure

    Limits on the production of scalar leptoquarks from Z (0) decays at LEP

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    A search has been made for pairs and for single production of scalar leptoquarks of the first and second generations using a data sample of 392000 Z0 decays from the DELPHI detector at LEP 1. No signal was found and limits on the leptoquark mass, production cross section and branching ratio were set. A mass limit at 95% confidence level of 45.5 GeV/c2 was obtained for leptoquark pair production. The search for the production of a single leptoquark probed the mass region above this limit and its results exclude first and second generation leptoquarks D0 with masses below 65 GeV/c2 and 73 GeV/c2 respectively, at 95% confidence level, assuming that the D0lq Yukawa coupling alpha(lambda) is equal to the electromagnetic one. An upper limit is also given on the coupling alpha(lambda) as a function of the leptoquark mass m(D0)

    Updated precision measurement of the average lifetime of B hadrons

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    The measurement of the average lifetime of B hadrons using inclusively reconstructed secondary vertices has been updated using both an improved processing of previous data and additional statistics from new data. This has reduced the statistical and systematic uncertainties and gives \tau_{\mathrm{B}} = 1.582 \pm 0.011\ \mathrm{(stat.)} \pm 0.027\ \mathrm{(syst.)}\ \mathrm{ps.} Combining this result with the previous result based on charged particle impact parameter distributions yields \tau_{\mathrm{B}} = 1.575 \pm 0.010\ \mathrm{(stat.)} \pm 0.026\ \mathrm{(syst.)}\ \mathrm{ps.

    Caracterización morfológica y de calidad de germoplasma de Capsicum colectado en el noroeste de Argentina

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    Paprika production is concentrated in Northwestern Argentina, where around 1500 ha are annually grown. Farmers mainly from Andean valleys, maintain their local landraces or "criollas" under different environmental conditions, using their farming traditions and selection criteria. These traditional varieties represent valuable genetic resources for conservation and selection of agronomical and quality traits. Between 2005 and 2007 eight collecting trips were made to Northwestern Argentina in order to recover local germplasm. As a result, five hundred new vegetable seed samples have been incorporated into the Germplasm Bank. Among these accessions 32 belong to Capsicum, the majority for paprika production, that were evaluated in field conditions using a randomized block design with three repetitions of eight plants per accession; 54 morphological and agronomical traits were measured during two production cycles. Multivariate analyses determine three groups, where fruit characters were the most efficient for accession differentiation. Accessions suitable for paprika production were further examined, and variability for fruit pungency and color was found. Promising accessions were selected for ex situ conservation and breeding purposes.La producción de pimiento para pimentón se concentra en el noroeste de la Argentina, donde anualmente se cultivan unas 1500 hectáreas. En los valles andinos los agricultores mantienen sus variedades locales o “criollas” en diferentes condiciones ambientales y siguiendo sus tradiciones agrícolas y criterios de selección. Estas variedades son recursos genéticos valiosos para la conservación y selección de caracteres agronómicos y de calidad. Entre 2005 y 2007 se realizaron ocho viajes a dicha zona, con el fin de recuperar el germoplasma local. Como resultado 500 nuevas muestras de semillas de hortalizas se han incorporado en el Banco de Germoplasma. Entre ellas 32 entradas de Capsicum, la mayoría utilizadas para la producción de pimentón, que se evaluaron a campo mediante un diseño de bloques al azar con tres repeticiones de ocho plantas por entrada, y se midieron 54 caracteres morfológicos y agronómicos durante dos ciclos de producción. El análisis multivariado determinó tres grupos, donde los caracteres del fruto fueron más eficientes para la diferenciación de las entradas. Se estudiaron en particular las entradas para la producción de pimentón, encontrándose variabilidad en el picor y en el color del fruto. Las entradas promisorias fueron seleccionadas para su conservación ex situ y mejoramiento

    First collection of landrace vegetable crops cultivated in Valle Fértil, Argentina Primera colección de hortalizas criollas cultivadas en Valle Fértil, Argentina

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    The richness of the cultural values found in the Argentinean Andean communities is integrated by a varied diversity of genetic resources, the development of a sustainable agriculture, and the conservation of the producer's own seeds. Local agriculture is a family economic activity, in which traditional varieties of vegetable landraces are highly appreciated for their flavour, colour and aromas. However; social, economic and environmental factors have an effect on crop diversity conservation. The main aim of this work was to retrieve and maintain a representative collection of traditional crop genetic resources still cultivated in the District of Valle Fértil, San Juan Province, Argentina, and to document the farmers' crop experiences and uses. Fifty families were interviewed; 26 of these donated a total of 49 samples belonging to eight species. The landraces collected showed a geometric distribution, typical of communities with low number of species; and a pattern of dominance. A few species are present in almost all farms while rare species are found in specific environments. Local germplasm recovery can prevent genetic erosion, so that both the formal breeding sector and the farmers can make use of the diversity of this collection.La riqueza cultural de las comunidades andinas de la Argentina está integrada por la diversidad de sus recursos genéticos, el desarrollo de un sistema agrícola sostenible y por el mantenimiento de sus semillas. La agricultura local es una actividad económica familiar, donde las variedades tradicionales de hortalizas son muy apreciadas por su sabor, color y aroma. Sin embargo, distintos factores sociales, económicos y ambientales afectan la diversidad de tales cultivos. Los objetivos de este trabajo fueron recuperar y conservar una muestra representativa de los recursos genéticos vegetales tradicionales aún presentes en el departamento de Valle Fértil, provincia de San Juan, Argentina, y documentar las experiencias y usos de ellos por parte de los productores. Se entrevistaron 50 familias de las cuales 26 donaron un total de 49 muestras pertenecientes a ocho especies. Las variedades criollas recolectadas mostraron una distribución geométrica típica en comunidades con pocas especies, y un patrón de dominancia donde algunas especies están presentes en casi todas las huertas mientras que especies poco representadas se encuentran en ambientes específicos. La recuperación del germoplasma local puede prevenir la erosión genética, de modo que tanto los mejoradores como los productores puedan aprovechar la diversidad de esta colección
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