715 research outputs found

    Transpiración nocturna en vid

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    Se presentan las medidas de transpiración media cada quince minutos, de la vid (Vitis vinifera cv. Tempranillo), en tres periodos fenológicos del cultivo: cerrado de racimo, envero y maduración. El estudio se realizó en dos plantas de 16 años de edad, a un marco de plantación de 3 m x 1,5 m, regadas mediante goteo y plantadas en un lisímetro de pesada continua monolítico de 9 m2 de superficie. Con la finalidad de poder medir la transpiración, la superficie del lisímetro fue cubierta con una lona impermeable, para evitar la pérdida de agua por evaporación, dejándose únicamente al aire libre el cultivo; de esta manera, las medidas registradas de pérdida de peso se debieron únicamente al efecto de la transpiración. Los resultados indicaron transpiración antes y después de la salida del sol, oscilando los valores de un 7% a un 16%, con respecto a la transpiración total del día.Ministerio de Economía y Competitividad AGL2014- 54201-C4-4-RMinisterio de Economía y Competitividad RTA2011-00100-C05-04Ministerio de Economía y Competitividad RTA 2014-00049-C05-0

    Magnetism and structure of LixCoO2 and comparison to NaxCoO2

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    The magnetic properties and structure of LixCoO2 for x between 0.5 and 1.0 are reported. Co4+ is found to be high-spin in LixCoO2 for x between 0.94 and 1.0 and low-spin for x between 0.50 and 0.78. Weak antiferromagnetic coupling is observed, increasing in strength as more Co4+ is introduced. At an x value of about 0.65, the temperature-independent contribution to the magnetic susceptibility and the electronic contribution to the specific heat are largest. Neutron diffraction analysis reveals that the lithium oxide layer expands perpendicular to the basal plane and the Li ions displace from their ideal octahedral sites with decreasing x. A comparison of the structures of the NaxCoO2 and LixCoO2 systems reveals that the CoO2 layer changes substantially with alkali content in the former but is relatively rigid in the latter. Further, the CoO6 octahedra in LixCoO2 are less distorted than those in NaxCoO2. We postulate that these structural differences strongly influence the physical properties in the two systems

    ¿Es posible mejorar la eficiencia en el uso del agua de un viñedo mediante un acolchado orgánico del suelo?

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    El objetivo de este trabajo fue evaluar el efecto que un acolchado orgánico del suelo (restos de poda) puede tener sobre la evapotranspiración del cultivo (ETc) de la vid con el fin de mejorar la eficiencia en el uso del agua. El estudio se realizó durante la campaña de 2015 en la finca “Las Tiesas”, Albacete (España). Las medidas se llevaron a cabo en un lisímetro monolítico de pesada ubicado en el centro de una parcela de vid (Vitis vinífera L., cv. Tempranillo) de 1 ha de superficie, y con cepas plantadas a un marco de 3 x 1,5 m y conducción en espaldera. Se llevaron a cabo tres ciclos de medidas, cada uno consistió en mantener el suelo desnudo durante los dos primeros días, los dos siguientes se cubrió la superficie del lisímetro con un acolchado orgánico (restos de poda de la vid) y los dos últimos días se cubrió el lisímetro con un acolchado inorgánico (lona de plástico). Los resultados indican que para la misma demanda evaporativa y fracción de cubierta vegetal, el acolchado orgánico redujo la ETc de la vid algo más de un 17%, mientras que el plástico la redujo un 25%. Los resultados obtenidos indican que con el acolchado orgánico sigue produciéndose una cierta evaporación de agua desde el suelo, pero se reduce considerablemente la ETc pudiéndose mejorar la eficiencia en el uso del agua.Ministerio de Economía y Competitividad FEDER AGL2014-54201-C4-4- RRTA 2011-00100-C05-04RTA 2014-00049-C05-0

    Estimación de la evaporación/transpiración en un cultivo de viña mediante radiometría térmica

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    La estimación precisa de la evapotranspiración de cultivo (ETc), así como su partición en las componentes evaporativa (E) y transpirativa (T), resultan fundamentales para mejorar la eficacia en la gestión del riego de cultivos en hilera en regiones áridas y semiáridas. El objetivo de este trabajo es contribuir a un mejor entendimiento de la partición E/T sobre viña llevando a cabo un balance de energía por separado para las componentes de suelo y de vegetación. En este trabajo se presentan los resultados de un experimento llevado a cabo en la finca de Las Tiesas, Albacete, de junio a octubre de 2013. Se instalaron un conjunto de radiómetros de infrarrojo térmico, apuntando directamente a las plantas y al suelo entre hileras. Se tomaron medidas de las cuatro componentes de la radiación neta, del flujo de calor en el suelo, además de variables meteorológicas y parámetros biofísicos. Todas las medidas se almacenaron en intervalos de 15 minutos, y se promediaron después a escala horaria y diaria. El valor medio observado de ETc fue de 3,1 mm día-1. La evaporación se estimó en torno al 30%. Los resultados presentados en este trabajo ofrecen una primera impresión de la partición E/T, y muestran el potencial de la caracterización térmica de la viña con este finAn accurate estimation of crop evapotranspiration (ETc), and its partition into both components, soil evaporation (E) and canopy transpiration (T), is known to be critical for a more effective irrigation scheduling of row-crops in arid and semi-arid environments. Vineyards are the best example in Mediterranean countries. The aim of this work is to improve our understanding of the E/T partition in vineyards by establishing a separate energy balance for soil and canopy components. An experiment was conducted in Las Tiesas experimental farm, Albacete (Spain), from June to October of 2013. A set of thermal-infrared radiometers were assembled pointing directly to the plants and the soil between rows. Measurements of the four components of the net radiation over the canopy and soil heat fluxes, as well as meteorological variables and biophysical parameters were all collected and stored every 15-min. Hourly and daily averages were then computed and analyzed. An average daily ETc value of 3.1 mm day-1 was observed in both sites. Interrow soil evaporation reached as much as 30% of the total ETc. These results provide a first insight into the partition E/T and show the potential of the vine thermal characterization with this aim.Ministerio de Economía y Competitividad CGL2013-46862-C2-1/2-PUnión Europea, AGL2014-54201-C4-4-RInstituto Nacional de Investigaciones Agrarias RTA 2011-00100-C05-04Instituto Nacional de Investigaciones Agrarias RTA 2014-00049-C05-03Generalitat Valenciana PROMETEOII/2014/08

    A new digital predictive predistorter for behavioral power amplifier linearization

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    This letter presents a new digital adaptive predistorter (PD) for power amplifier (PA) linearization based on a nonlinear auto-regressive moving average (NARMA) structure. The distinctive characteristic of this PD is its straightforward deduction from the NARMA PA model, without the need of using an indirect learningapproachto identify the PD function.The PD itself presents a NARMA structure, and hence it can be quickly implemented by means of lookup tables. Single and multicarrier modulated signals collected from a three-stage LDMOS class AB PA, with a maximum output power of 48-dBm CW have been used to validate the linearity performance of this new predictive predistorter.Peer Reviewe

    Novo neonicotinóide associado a regulador de crescimento de insetos, no controle da mosca-branca e do pulgão na cultura do algodão.

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    Resumo: O objetivo deste trabalho foi avaliar o desempenho da nova molécula química dinotefuram, pertencente ao grupo dos neonicotinóides, associada a um análogo do hormônio juvenil (piriproxifem), em aplicação foliar, no controle da mosca-branca B. tabaci Biótipo B e do pulgão A. gossypii, em algodoeiro. O delineamento foi em blocos ao acaso com quatro repetições. Os tratamentos foram: testemunha, dinotefuram + piriproxifem a 25 + 12,5; 50 + 12,5; 75 + 12,5; 25 + 25; 50 + 25; 75 + 25 e dinotefuram a 75 g i.a./ha. Cada parcela foi de 48m2. Para aplicação foliar, utilizou-se um pulverizador costal equipado com barra contendo seis pontas cônicas (TXVK-8), propelido por CO2 e volume de 200 L/ha. Foram realizadas avaliações de eficiência dos tratamentos aos 0, 5, 10, 15 e 20 dias após a aplicação, contando-se o número de ninfas de mosca-branca e o número de pulgões em 10 folhas por parcela. Pela análise dos resultados, concluiu-se que o inseticida dinotefuram associado ao piriproxifem, foi eficiente no controle de ninfas de mosca-branca e do pulgão, igualando-se aos padrões já utilizados

    Quantum mechanical modeling of excited electronic states and their relationship to cathodoluminescence of BaZrO3

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    First-principles calculations set the comprehension over performance of novel cathodoluminescence (CL) properties of BaZrO3 prepared through microwave-assisted hydrothermal. Ground (singlet, s*) and excited (singlet s** and triplet t** ) electronic states were built from zirconium displacement of 0.2 Å in {001} direction. Each ground and excited states were characterized by the correlation of their corresponding geometry with electronic structures and Raman vibrational frequencies which were also identified experimentally. A kind of optical polarization switching was identified by the redistribution of 4dz2 and 4dxz (Zr) orbitals and 2pz O orbital. As a consequence, asymmetric bending and stretching modes theoretically obtained reveal a direct dependence with their polyhedral intracluster and/or extracluster ZrO6 distortions with electronic structure. Then, CL of the as-synthesized BaZrO3 can be interpreted as a result of stable triplet excited states, which are able to trap electrons, delaying the emission process due to spin multiplicity changes

    STI epidemic re-emergence, socio-epidemiological clusters characterisation and HIV coinfection in Catalonia, Spain, during 2017-2019 : A retrospective population-based cohort study

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    Objectives To describe the epidemiology of sexually transmitted infections (STIs), identify and characterise socio-epidemiological clusters and determine factors associated with HIV coinfection. Design Retrospective population-based cohort. Setting Catalonia, Spain. Participants 42 283 confirmed syphilis, gonorrhoea, chlamydia and lymphogranuloma venereum cases, among 34 600 individuals, reported to the Catalan HIV/STI Registry in 2017-2019. Primary and secondary outcomes Descriptive analysis of confirmed STI cases and incidence rates. Factors associated with HIV coinfection were determined using logistic regression. We identified and characterized socio-epidemiological STI clusters by Basic Health Area (BHA) using K-means clustering. Results The incidence rate of STIs increased by 91.3% from 128.2 to 248.9 cases per 100 000 population between 2017 and 2019 (p<0.001), primarily driven by increase among women (132%) and individuals below 30 years old (125%). During 2017-2019, 50.1% of STIs were chlamydia and 31.6% gonorrhoea. Reinfections accounted for 10.8% of all cases and 6% of cases affected HIV-positive individuals. Factors associated with the greatest likelihood of HIV coinfection were male sex (adjusted OR (aOR) 23.69; 95% CI 16.67 to 35.13), age 30-39 years (versus <20 years, aOR 18.58; 95% CI 8.56 to 52.13), having 5-7 STI episodes (vs 1 episode, aOR 5.96; 95% CI 4.26 to 8.24) and living in urban areas (aOR 1.32; 95% CI 1.04 to 1.69). Living in the most deprived BHAs (aOR 0.60; 95% CI 0.50 to 0.72) was associated with the least likelihood of HIV coinfection. K-means clustering identified three distinct clusters, showing that young women in rural and more deprived areas were more affected by chlamydia, while men who have sex with men in urban and less deprived areas showed higher rates of STI incidence, multiple STI episodes and HIV coinfection. Conclusions We recommend socio-epidemiological identification and characterisation of STI clusters and factors associated with HIV coinfection to identify at-risk populations at a small health area level to design effective interventions
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