2,418 research outputs found

    Towards a more complete description of nucleon distortion in lepton-induced single-pion production at low-Q2Q^2

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    Theoretical predictions for lepton-induced single-pion production (SPP) on 12^{12}C are revisited in order to assess the effect of different treatments of the current operator. On one hand we have the asymptotic approximation, which consists in replacing the particle four-vectors that enter in the operator by their asymptotic values, i.e., their values out of the nucleus. On the other hand we have the full calculation, which is a more accurate approach to the problem. We also compare with results in which the final nucleon is described by a relativistic plane wave, to rate the effect of the nucleon distortion. The study is performed for several lepton kinematics, reproducing inclusive and semi-inclusive cross sections belonging to the low-Q2Q^2 region (between 0.05 and 1 GeV2^2), which is of special interest in charged-current (CC) neutrino-nucleus 1π\pi production. Inclusive electron results are compared with experimental data. We find non-trivial corrections comparable in size with the effect of the nucleon distortion, namely, corrections up to 6\%, either increasing or diminishing the asymptotic prediction, and a shift of the distributions towards higher energy transfer. For the semi-inclusive cross sections, we observe the correction to be prominent mainly at low values of the outgoing nucleon kinetic energy. Finally, for CC neutrino-induced 1π+\pi^+ production, we find a reduction at low-Q2Q^2 with respect to both the plane-wave approach and the asymptotic case

    Leucaena leucocephala in ruminant nutrition

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    It is a common situation in extensive ruminant production systems in tropical countries to have low production indicators due to nutrient deficiencies in the diet. An economic alternative to increase animal production is the incorporation of legumes (fodder and fruits) in the diet. This review, presents an analysis of the positive and negative effects of Leucaena leucocephala consumption by ruminants, with particular emphasis on the secondary compound mimosine. Leucaena due to its high nutrient content, rumen by-pass protein supply and its possible effect on the reduction of greenhouse gas (attributed to tannins) has become one of the legumes most commonly used in ruminant feeding practices. However, in countries where leucaena has been introduced, its use is still limited to levels below 30% inclusion in the diet, due to the secondary compound mimosine and its isomers (3,4 and 2,3 DHP), which can induce toxicity, even when animals are inoculated with rumen fluid containing the bacteria Synergistes jonesii reported as responsible for degrading these compounds in the rumen. In the Yucatan Peninsula, Mexico, ruminants consuming leucaena can tolerate more than 50% inclusion in the diet, without having a negative impact on production, attributed intake to mimosine and its isomers. We conclude that in animals not adapted, the intake would be limited to low inclusion levels (less than 30% inclusion in the diet), mainly because of mimosine and its derivatives. The decrease in intake or diet digestibility seem to better explain the reduction in methane production, however, in vivo studies are required to clearly establish the mechanism of action. It has been reported the presence of different bacteria to S. jonessi that would have the ability to degrade mimosine and its derivatives, however, the activity of these bacteria and its effectiveness must be confirmed in vivo

    Hollow-core fiber-based speckle displacement sensor

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    The research enterprise towards achieving high-performance hollow-core photonic crystal fibers has led to impressive advancements in the latest years. Indeed, using this family of fibers becomes nowadays an overarching strategy for building a multitude of optical systems ranging from beam delivery devices to optical sources and sensors. In most applications, an effective single-mode operation is desired and, as such, the fiber microstructure or the light launching setups are typically designed for achieving such a behavior. Alternatively, one can identify the use of large-core multimode hollow-core fibers as a promising avenue for the development of new photonic devices. Thus, in this manuscript, we propose and demonstrate the utilization of a large-core tubular-lattice fiber for accomplishing a speckle-based displacement sensor, which has been built up by inserting and suitably dislocating a single-mode fiber inside the void core of the hollow fiber. The work reported herein encompasses both simulation and experimental studies on the evolution of the multimode intensity distributions within the device as well as the demonstration of a displacement sensor with an estimated resolution of 0.7 {\mu}m. We understand that this investigation identifies a new opportunity for the employment of large-core hollow fibers within the sensing framework hence widening the gamut of applications of this family of fibers

    All-fiber broadband spectral acousto-optic modulation of a tubular-lattice hollow-core optical fiber

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    We demonstrate a broadband acousto-optic notch filter based on a tubular-lattice hollow-core fiber for the first time. The guided optical modes are modulated by acoustically induced dynamic long-period gratings along the fiber. The device is fabricated employing a short interaction length (7.7 cm) and low drive voltages (10 V). Modulated spectral bands with 20 nm half-width and maximum depths greater than 60 % are achieved. The resonant notch wavelength is tuned from 743 to 1355 nm (612 nm span) by changing the frequency of the electrical signal. The results indicate a broader tuning range compared to previous studies using standard and hollow-core fibers. It further reveals unique properties for reconfigurable spectral filters and fiber lasers, pointing to the fast switching and highly efficient modulation of all-fiber photonic devices

    All-fiber fast acousto-optic temporal control of tunable optical pulses

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    We demonstrate a new all-fiber electrically tunable modulation method which significantly reduces the response time of a Bragg grating acousto-optic modulator. A 4 cm long device is fabricated with a 1 cm grating inscribed in a suspended core fiber. An acoustic pulse train is switched out of phase along the fiber, damping unwanted natural resonant vibrations inside the grating. The device rise time is decreased from 56 to 9 µs by tuning the duty cycle of the driven electrical signal, contributing to achieve the shortest switching time of 15.6 µs. This tunable temporal response reveals unique features to change the profile of optical pulses. High pulse modulation depths are achieved employing a compact acousto-optic modulator, pointing to fast switching of all-fiber photonic devices

    Evaluación de la eficacia de diferentes insecticidas químicos para el control de la oruga del cascabullo, Helicoverpa gelotopoeon Dyar (Lepidoptera: Noctuidae), en el cultivo de garbanzo

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    En la campaña 2010, la superficie cultivada con garbanzo en la Argentina fue de 40.000 ha, lo que significó un crecimiento del 150% con respecto a la campaña 2009 (Vizgarra et al., 2011). En la provincia de Tucumán y zonas de influencia (sudeste de Catamarca y oeste de Santiago del Estero), la superficie sembrada superó las 25.000 ha para la campaña 2011, producto del buen precio que tuvo esta legumbre en el 2010, que la posicionó como una interesante alternativa invernal (Vizgarra et al., 2012).Fil: Scalora, Franco S.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Casmuz, Augusto S.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Cazado, Lucas Emiliano. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán; ArgentinaFil: Aralde, Marcos R.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Aybar Guchea, Matías. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Fadda, Lucas A.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gómez, Mario. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gómez, César Horacio. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Tolosa, Gerardo J.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Vera, Martín A.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gastaminza, Gerardo A.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Willink, Eduardo. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Vizgarra, Oscar N.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Rodriguez, Walter. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentin

    Impacto del daño ocasionado por el picudo negro de la vaina, Rhyssomatus subtilis Fiedler (Coleoptera: Curculionidae), en diferentes etapas fenológicas del cultivo de soja

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    El picudo negro de la soja, Rhyssomatus subtilis Fiedler, es una plaga ampliamente difundida en gran parte del Noroeste Argentino y la soja constituye uno de sus cultivos hospederos preferidos (Cazado et al., 2013). El picudo afecta al cultivo durante todo su ciclo. En la etapa vegetativa, los adultos se alimentan de los cotiledones, tallos y brotes tiernos de las plantas, llegando a comprometer su estructura e incluso ocasionando su muerte. En la etapa reproductiva, tanto el adulto como la larva causan perjuicios al cultivo. Durante la formación de los granos, las hembras colocan los huevos en el interior de las vainas de soja. Las larvas, al nacer, se alimentan de los granos verdes, llegando a consumir uno o más granos dentro de una misma vaina. La alimentación de las larvas incide en forma directa sobre el rinde del cultivo (Socías et al., 2009). Además, los orificios de alimentación y oviposición constituyen vías de ingreso para patógenos que afectan la calidad de la semilla (Escobar et al., 2009).Fil: Cazado, Lucas Emiliano. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Casmuz, Augusto Sebastián. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Scalora, Franco S.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Aralde, Marcos R.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Aybar Guchea, Matías. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Colledani Toranzo, G. Alejandro. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gómez, Mario. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Fadda, Lucas A.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Fernández, José L.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gómez, César Horacio. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentina. Consejo Nacional de Investigaciones Científicas y Técnicas; ArgentinaFil: Gastaminza, Gerardo Alfredo. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Willink, Eduardo. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentin

    Evaluación de diferentes alternativas para el control del complejo de orugas defoliadoras y el impacto de éstas sobre el rendimiento del cultivo de soja

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    El orden Lepidoptera agrupa la mayor cantidad de especies cuyas larvas causan daños de importancia al cultivo de soja. Entre estas, las de mayor importancia son las especies de hábitos defoliadores, especialmente Anticarsia gemmatalis, Rachiplusia nu y Chrysodeixis (Pseudoplusia) includens. Cabe destacar que esta última especie se muestra tolerante a las dosis normales de insecticidas empleadas para el control de las otras dos 1 orugas.Fil: Casmuz, Augusto S.. Estacion Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Scalora, Franco S.. Estacion Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Cazado, Lucas Emiliano. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Tucumán. Instituto de Tecnología Agroindustrial del Noroeste Argentino; Argentina. Estacion Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Aralde, Marcos R.. Estacion Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Aybar Guchea, Matías. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gómez, Mario. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Fadda, Lucas A.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Colledani Toranzo, Alejandro. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Fernández, José L.. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Vera, Alejandro. Estacion Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gómez, Horacio. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Gastaminza, Gerardo Alfredo. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; ArgentinaFil: Moa, Darío. Gobierno de Tucumán. Ministerio de Desarrollo Productivo. Estación Experimental Agroindustrial Obispo Colombres; Argentin

    A new polyacetylene from Vernonia scorpioides (Lam.) Pers. (Asteraceae) and its in vitro antitumoral activity

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    The dichloromethane fraction obtained from hydroalcoholic crude extract of leaves and flowers of Vernonia scorpioides (Asteraceae) was investigated, resulting in the isolation and structure elucidation of a new polyacetylene namely 5-octa-2,4,6-triynyl-furan-2(5H)-one. The structure of the isolated compound was determined based on IR, NMR (1D and 2D) and MS spectrometric data. The antitumor potential, including cytotoxicity to tumor cells and genotoxicity, was investigated. The results suggest that apoptotic cell death may have occurred, at least in part, via a caspase-dependent mechanism.A fração diclorometano obtida pelo particionamento do extrato hidroalcoólico obtido das folhas e flores de Vernonia scorpioides (Asteraceae) resultou no isolamento e caracterização de um novo poliacetileno, 5-octa-2,4,6-triinil-furan-2(5H)-ona. A determinação estrutural foi baseada em dados de espectrometria de Ressonância Magnética Nuclear mono e bidimensionais, de Massas e de Infravermelho. Foi investigado o potencial antitumoral e genotóxico do novo poliacetileno e os resultados encontrados sugerem genotoxicidade e citotoxicidade, onde a morte celular ocorreu via apoptose, envolvendo um mecanismo dependente de caspase.13271333Conselho Nacional de Desenvolvimento Científico e Tecnológico (CNPq)Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES
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