15 research outputs found

    Efecto del riego por goteo en el rendimiento y contenido de antocianinas en cultivares de maíz morado (Zea mays L.)

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    En condiciones de cambio climático, el uso óptimo del recurso hídrico y adecuado manejo agronómico, tienen como propósito incrementar el rendimiento y calidad de las cosechas, en tal sentido, el objetivo del ensayo fue evaluar el efecto de tres caudales hídricos suministrados por goteo (C1-1,6 LH-1; C2-1,4LH-1 y C3-1,2 LH-1); en el rendimiento y contenido de antocianinas en cultivares de maíz morado (V1:PMV-581; V2:MMMejorado y V3:MMComun) . Se utilizó el DBCA con factorial. Los resultados para diámetro de mazorcas reportaron que las interacciones C1xV2 y C1xV1, registraron promedios de 4,83 y 4,77 cm respectivamente; para peso de mazorcas por área neta con la interacción C1xV1 se obtuvo el mayor promedio de 4,78 kg, y asimismo un rendimiento equivalente a 11 950 kg.ha-1 .Mayor contenido de antocianinas se obtuvo con la interacción C1xV1 con 88,71 mg.L-1; y con la C2xV1 se obtuvo 74,95 mg.L-1. Se concluye que la interacción C1V1 denoto el mayor rendimiento por hectárea así como el mayor contenido de antocianinas

    Susceptibility of larval stages of Leptophobia aripa Boisduval (Lepidoptera: Pieridae) to entomopathogens

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    Under laboratory conditions, the efficacy of four formulations based on Bacillus subtilis, Bacillus thuringiensis var kurstaki, Metarhizium anisopliae, Beauveria bassiana plus a control (distilled water) on the larval development stages of the Leptophobia aripa Boisduval plague were evaluated. 15 larvae were collected for each stage, placed in groups of 5 per plate for a total of five treatments with three repetitions. As food, leaves of the cabbage crop were taken and sprinkled with the products as appropriate. The larvae were examined under a stereoscopic microscope for 7 days, and the Abbott formula was used to determine the percentage of mortality. Among the results, in the case of the first and second larval stage, the entomopathogens B. thuringiensis var kurstaki had higher efficiency with 56.70% and 60% mortality respectively, in the third and fourth stage the species B. bassiana shows greater effectiveness with 66.70% and 50%, in the fifth stage M. anisopliae registers a mortality of 36.70%. The third larval stage was selected as the most susceptible to the application of B. thuringiensis var kurstaki, B. bassiana and M. anisopliae respectively.En condiciones de laboratorio se evaluó la eficacia de cuatro formulados a base de Bacillus subtilis, Bacillus thuringiensis var kurstaki, Metarhizium anisopliae, Beauveria bassiana más un testigo (agua destilada) sobre los estados de desarrollo larval de la plaga Leptophobia aripa Boisduval. Se colectaron 15 larvas por cada estadio, colocadas en grupos de 5 por placa para un total de cinco tratamientos con tres repeticiones. Como alimento se ocuparon hojas del cultivo de col que fueron asperjadas con los productos según corresponda. Las larvas se examinaron al microscopio estereoscópico por 7 días, y para la determinación del porcentaje de mortalidad se utilizó la fórmula de Abbott. Entre los resultados se tiene que, para el caso del primer y segundo estadio larval, el entomopatógeno B. thuringiensis var kurstaki tuvo mayor eficiencia con un 56,70% y 60% de mortalidad respectivamente, en el tercer y cuarto estadio la especie B. bassiana muestra mayor efectividad con 66,70% y 50%, en el quinto estadio el M. anisopliae registra una mortalidad de 36,70%. Se seleccionó al tercer estadio larval como el más susceptible a la aplicación de B. thuringiensis var kurstaki, B. bassiana y M. anisopliae respectivamente

    Brown dwarfs and very low mass stars in the Praesepe open cluster: a dynamically unevolved mass function?

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    [Abridged] In this paper, we present the results of a photometric survey to identify low mass and brown dwarf members of the old open cluster Praesepe (age of 590[+150][-120]Myr and distance of 190[+6.0][-5.8]pc) and use this to infer its mass function which we compare with that of other clusters. We have performed an optical (Ic-band) and near-infrared (J and Ks-band) photometric survey of Praesepe with a spatial coverage of 3.1deg^2. With 5sigma detection limits of Ic=23.4 and J=20.0, our survey is sensitive to objects with masses from about 0.6 to 0.05Msol. The mass function of Praesepe rises from 0.6Msol down to 0.1Msol and then turns-over at ~0.1Msol. The rise observed is in agreement with the mass function derived by previous studies, including a survey based on proper motion and photometry. Comparing our mass function with that for another open cluster with a similar age, the Hyades (age ~ 600Myr), we see a significant difference. Possible reasons are that dynamical evaporation has not influenced the Hyades and Praesepe in the same way, or that the clusters did not have the same initial mass function, or that dynamical interactions have modified the evolution of one or both clusters. Although a difference in the binary fractions of the clusters could cause the observed (i.e. system) mass functions to differ, measurements in the literature give no evidence for a significant difference in the binary fractions of the two clusters. Of our cluster candidates, six have masses predicted to be equal to or below the stellar/substellar boundary at 0.072Msol.Comment: 11 pages, 11 figures, accepted for publication in A&A. Higher resolution of Figures 2-3-4-5 in A&A published version. Revised version corrected for Englis

    Low mass stars, brown dwarf candidates and the mass function of the young open cluster NGC 2547

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    We present a catalogue of RIZ photometry over an area of 0.855 square degrees, centred on NGC 2547. The survey is substantially complete to limits of R_c=21.5, I_c=19.5, Z=19.5. We use the catalogue to define NGC 2547 candidates with masses of about 0.05-1.0 M_sun. After correcting for incompleteness and contamination by foreground field dwarfs, we investigate the mass function of the cluster, its binary content, and search for evidence of mass segregation among lower mass stars. There is evidence for mass segregation between high (>3 M_sun) and lower mass stars, but over the range 0.1<M<0.7 M_sun, the data are consistent with no further mass segregation. By fitting King profiles we conclude that at least 60 percent of the low-mass stellar population are contained in our survey. The cluster mass function is remarkably similar to the Pleiades for 0.075<M<0.7 M_sun. Because of its age (~30 Myr), we demonstrate that this mass function is robust to several systematic uncertainties likely to affect older and younger clusters and is therefore one of the best available estimates for the initial mass function in young disc populations. For 0.05<M<0.075 M_sun there is some evidence for a deficit of brown dwarfs in NGC 2547 compared with other clusters. This deficit may extend to lower masses or may only be a dip, perhaps caused by an imperfect understanding of the mass-magnitude relationship at temperatures of 2800K.Incompleteness in our survey, and the luminosity functions from which we estimate contamination, leave this question open. The binary fraction for systems with mass ratios greater than about 0.5 is 20-35 per cent for M-dwarfs in NGC 2547, quite consistent with that found in the field (abridged).Comment: 24 pages, accepted for MNRAS. Version with better Figures and electronic catalogues available from http://www.astro.ex.ac.uk/people/timn/Catalogues/description.htm

    The stellar and sub-stellar IMF of simple and composite populations

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    The current knowledge on the stellar IMF is documented. It appears to become top-heavy when the star-formation rate density surpasses about 0.1Msun/(yr pc^3) on a pc scale and it may become increasingly bottom-heavy with increasing metallicity and in increasingly massive early-type galaxies. It declines quite steeply below about 0.07Msun with brown dwarfs (BDs) and very low mass stars having their own IMF. The most massive star of mass mmax formed in an embedded cluster with stellar mass Mecl correlates strongly with Mecl being a result of gravitation-driven but resource-limited growth and fragmentation induced starvation. There is no convincing evidence whatsoever that massive stars do form in isolation. Various methods of discretising a stellar population are introduced: optimal sampling leads to a mass distribution that perfectly represents the exact form of the desired IMF and the mmax-to-Mecl relation, while random sampling results in statistical variations of the shape of the IMF. The observed mmax-to-Mecl correlation and the small spread of IMF power-law indices together suggest that optimally sampling the IMF may be the more realistic description of star formation than random sampling from a universal IMF with a constant upper mass limit. Composite populations on galaxy scales, which are formed from many pc scale star formation events, need to be described by the integrated galactic IMF. This IGIMF varies systematically from top-light to top-heavy in dependence of galaxy type and star formation rate, with dramatic implications for theories of galaxy formation and evolution.Comment: 167 pages, 37 figures, 3 tables, published in Stellar Systems and Galactic Structure, Vol.5, Springer. This revised version is consistent with the published version and includes additional references and minor additions to the text as well as a recomputed Table 1. ISBN 978-90-481-8817-

    Comprensión y Producción de Lenguaje I - HU543 - 202101

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    Descripción: Comprensión y Producción de Lenguaje 1 es un curso de primer ciclo, que busca desarrollar las habilidades vinculadas con la comprensión lectora y la redacción de textos escritos formales y adecuados a una situación comunicativa determinada. Por ello, durante el curso, las actividades posibilitarán que el estudiante reflexione sobre cómo el lenguaje es una herramienta que nos permite entender la realidad (comprensión) y comunicar adecuadamente nuestras ideas sobre ella (producción). Esta reflexión se realizará con énfasis en el uso del lenguaje en las redes sociales, espacio que se ha constituido como un nuevo lugar para la divulgación de asuntos diversos: desde temas de ocio o entretenimiento hasta temas académicos, científicos y políticos. En ese sentido, este curso propone que el alumno asuma el rol de un ciudadano crítico, es decir, aquella persona que no solo consume información, sino que produce contenido a partir de una investigación en fuentes confiables. Considerando lo explicado, nuestros alumnos no solo serán capaces de redactar un texto escrito formal de acuerdo con las necesidades comunicativas del ámbito universitario y de la sociedad actual, sino que podrán transformarlo en un texto multimodal (el cual involucra diferentes medios de comunicación: visual, auditivo, imagen, texto, entre otros) que tenga sentido en las redes sociales, lugar de interacción real con sus lectores. Estos productos comunicativos deberán presentar una organización conveniente, un desarrollo sólido y suficiente (lo que implica una lectura crítica de las fuentes de información), y una escritura acorde con la normativa vigente. 3 Propósito: El curso desarrolla la competencia de comunicación escrita, en el nivel 1; es decir, el estudiante es capaz de construir mensajes coherentes y sólidos que se adecúan a la situación y propósito comunicativo. Este desarrollo le permite la generación y construcción de nuevas ideas, lo cual es relevante para su vida académica y profesional. La actual sociedad de la información y el conocimiento, caracterizada por la disrupción, la innovación y la complejidad en las formas de comunicación mediadas por la tecnología, enfrenta al estudiante y al profesional a nuevos retos en las maneras de comunicar aquello que conoce y que construye. En este escenario, la competencia comunicativa escrita adquiere protagonismo como herramienta para transmitir el conocimiento creado. El curso se alinea con esta exigencia, pues contribuye a que el estudiante responda exitosamente a las demandas comunicativas del contexto académico, y a que el egresado pueda desenvolverse idóneamente en el campo profesional y laboral

    The Present and Future of QCD

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    International audienceThis White Paper presents the community inputs and scientific conclusions from the Hot and Cold QCD Town Meeting that took place September 23-25, 2022 at MIT, as part of the Nuclear Science Advisory Committee (NSAC) 2023 Long Range Planning process. A total of 424 physicists registered for the meeting. The meeting highlighted progress in Quantum Chromodynamics (QCD) nuclear physics since the 2015 LRP (LRP15) and identified key questions and plausible paths to obtaining answers to those questions, defining priorities for our research over the coming decade. In defining the priority of outstanding physics opportunities for the future, both prospects for the short (~ 5 years) and longer term (5-10 years and beyond) are identified together with the facilities, personnel and other resources needed to maximize the discovery potential and maintain United States leadership in QCD physics worldwide. This White Paper is organized as follows: In the Executive Summary, we detail the Recommendations and Initiatives that were presented and discussed at the Town Meeting, and their supporting rationales. Section 2 highlights major progress and accomplishments of the past seven years. It is followed, in Section 3, by an overview of the physics opportunities for the immediate future, and in relation with the next QCD frontier: the EIC. Section 4 provides an overview of the physics motivations and goals associated with the EIC. Section 5 is devoted to the workforce development and support of diversity, equity and inclusion. This is followed by a dedicated section on computing in Section 6. Section 7 describes the national need for nuclear data science and the relevance to QCD research
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