882 research outputs found

    Impact assessment of irrigation management transfer in the Alto Rio Lerma Irrigation District, Mexico

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    Irrigation managementPrivatizationAssessmentEconomic aspectsLegal aspectsData collectionWater rightsWater allocationWater distributionGroundwaterFinancingMaintenanceOperationsAgricultural productionWater users' associationsFarmer participation

    Western Mediterranean climate and environment since Marine Isotope Stage 3: a 50,000-year record from Lake Banyoles, Spain

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    We present new stable isotope (δ¹⁸Ocalcite and δ¹³ Ccalcite) and diatom data from a 67-m sediment core (BAN II) from Lake Banyoles, northeastern Spain. We reassessed the chronology of the sequence by correlating stable isotope data with a shorter U-series-dated record from the lake, confirming a sedimentological offset between the two cores and demonstrating that BAN II spans Marine Isotope Stages (MIS) 3–1. Through comparison with previous records, the multi-proxy data are used to improve understanding of palaeolimnological dynamics and, by inference, western Mediterranean climate and environmental change during the past ca. 50,000 years. Three main zones, defined by isotope and diatom data, correspond to the MIS. The basal zone (MIS 3) is characterised by fluctuating δ¹⁸Ocalcite and benthic diatom abundance, indicating a high degree of environmental and climate variability, concomitant with large lake-level changes. During the full glacial (MIS 2), relatively constant δ¹⁸Ocalcite and a poorly preserved planktonic-dominated diatom assemblage suggest stability, and intermittently, unusually high lake level. In MIS 1, δ¹⁸Ocalcite and δ¹³Ccalcite initially transition to lower values, recording a pattern of Late Glacial to Holocene change that is similar to other Mediterranean records. This study suggests that Lake Banyoles responds limnologically to changes in the North Atlantic ocean–atmosphere system and provides an important dataset from the Iberian Peninsula, a region in need of longer-term records that can be used to correlate between marine and terrestrial archives, and between the western and eastern Mediterranean

    Crop-based irrigation operations in the North West Frontier Province of Pakistan. Vol.II: Research approach and interpretation. Final Report

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    Irrigation management / Crop-based irrigation / Research / Irrigation canals / Water demand / Performance evaluation / Agricultural production / Pakistan / North West Frontier Province

    Alloy Interface Interdiffusion Modeled

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    With renewed interest in developing nuclear-powered deep space probes, attention will return to improving the metallurgical processing of potential nuclear fuels so that they remain dimensionally stable over the years required for a successful mission. Previous work on fuel alloys at the NASA Glenn Research Center was primarily empirical, with virtually no continuing research. Even when empirical studies are exacting, they often fail to provide enough insight to guide future research efforts. In addition, from a fundamental theoretical standpoint, the actinide metals (which include materials used for nuclear fuels) pose a severe challenge to modern electronic-structure theory. Recent advances in quantum approximate atomistic modeling, coupled with first-principles derivation of needed input parameters, can help researchers develop new alloys for nuclear propulsion

    The Effects of Night-time Temperatures on Physiological and Biochemical Traits in Rice

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    High nighttime temperatures impair rice yield. Additionally, heat stress periods have increased during the last years in the rice areas of the tropics. The aim of this study was to physiologically characterize six genotypes of rice (a commercial cultivar (ʻF60ʼ) and five selected lines (ʻIR 1561ʼ, ʻFLO 2764ʼ, ʻLV447-1ʼ, ʻCT19021ʼ, and ʻLV1401ʼ) subjected to two nighttime temperatures (24 and 30 °C), based on different physiological traits. When the collar formed on leaf 6 of the main stem, one group of six plants in each genotype was subjected to 30 °C from 18:00 to 24:00 hours for eight days, while the other group remained at 24 °C. Differences were found in the interaction between genotype and nighttime temperatures, where a high night temperature reduced leaf photosynthesis by approximately 50% in all genotypes compared to the controls (20 µmol vs. 10 µmol CO2 m-2 s-1, respectively). In general, higher plant respiration was also observed in almost all genotypes when the plants were exposed to 30 °C. However, rice plants of the genotype ʻF60ʼ showed a constant respiration under two different night temperatures. A high nighttime temperature increased the electrolyte leakage and malondialdehyde content only in the ʻLV1401ʼ plants. Plant growth and Fv/Fm ratio were separately conditioned by the night temperature or the genotype factor. A lower total plant dry weight was found at 30 °C (620.36 mg) than in rice plants exposed to 24 °C (254.16 mg). The Fv/Fm ratio was slightly diminished at a high nighttime temperature. These results suggest that physiological variables, such as leaf photosynthesis, plant respiration, malondialdehyde content and leaf photosynthetic pigments, can be considered markers for characterizing tolerant genotypes in earlier growth phases during plant breeding programs

    Social and medical aspects longevity

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    The article deals with the demographical problem's population aging, life expectancy, premature aging, are shown results on quality of life in countries in relation to different indexes, that form itye

    Producción de semilla certificada de papa

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    El cultivo de la papa ha alcanzado gran importancia en el país en los últimos años, creemos que sea conveniente presentar una relación sobre las más comunes enfermedades y accidentes del cultivo y sobre los métodos que aquí o en otros países se están empleando para combatirlas. Esto parece aún más importante ahora, cuando estamos entrando en la fase de la producción de semilla certificada, para cuya organización y buen éxito es indispensable conocer a fondo y distinguir claramente los diversos tipos de enfermedades que atacan al cultivo

    Enfermedades producidas por priones en los Animales

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    Las encefalopatías espongiformes transmisibles (EETs) o enfermedades producidas por priones, son un grupo de enfermedades neurodegenerativas, de progresión lenta y fatales. Afectan tanto a los humanos como a los animales. Dentro de este grupo se encuentra la Encefalopatía Espongiforme Bovina (EEB), que se diagnosticó en Gran Bretaña y que posteriormente ha afectado a otros países. Esta patología ha causado gran impacto por el daño que ha provocado en la salud animal, en la economía y por su relevancia en la salud pública de estos países, al ser una enfermedad zoonótica. El agente etiológico de todas las EETs, se denomina "prión", que corresponde a la forma alterada (PrPSc) de una proteína constitutiva de la membrana celular (PrPC). La forma patológica es infectiva, capaz de producir la enfermedad, extremadamente resistente al calor y a otros métodos tradicionales de esterilización, que son efectivos contra otros patógenos. Entre las características comunes de estas patologías, se incluyen su curso con un largo periodo de incubación, el que puede durar hasta 3 años, posterior a la exposición. Los signos clínicos aparecen después de este período, los animales afectados presentan signos neurológicos progresivos y cambios morfológicos degenerativos del sistema nervioso central, que terminan con la muerte del individuo. Las principales EETs en los animales, que se describen en este trabajo son: el scrapie de ovinos y caprinos, la Encefalopatía Espongiforme Bovina (EEB), la Encefalopatía Transmisible del Visón (ETV), la Enfermedad del Desgaste Crónico (EDC) en ciervos y alces y la Encefalopatía Espongiforme Felina (EEF).  

    Rice seedlings showed a higher heat tolerance through the foliar application of biostimulants

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    The use of biostimulants is an agronomic tool to improve plant tolerance to abiotic stress in plants. This study explored the effect of foliar biostimulants sprays such as brassinosteroids (BR), amino acids (AA), nitrophenolates (NP) or a biostimulant based on botanical extracts (BE) on leaf gas exchange parameters [photosynthesis (PN), stomatal conductance (gs) and transpiration (E)], leaf photosynthetic pigments, lipid peroxidation of membranes and proline content of two commercial rice genotypes [‘Fedearroz 67’ and ‘Fedearroz 60’] under heat stress conditions. The established treatments were: i) plants without heat stress and foliar applications of biostimulants (C), ii) plants under heat stress and without foliar applications of biostimulants (HT), and iii) plants with heat stress and three foliar applications with BR (1 mL·L-1), AA (30 mL·L-1), NP (15 mL·L-1) or BE (15 mL·L-1). The results showed that the application of BR, AA, NP or BE increased the values ​​of PN (~14.5 µmol CO2·m-2·s-1), gs (~0.46 mmol·m-2·s-1) and E (~43.9 H20 day-1·plant-1) compared to plants (both genotypes) not treated with biostimulants under heat stress (9.9 µmol CO2·m-2·s-1 for PN, 0.31 mmol·m-2·s-1 for gs, and 27.3 H20 day-1·plant-1 for E). Foliar biostimulant sprays also caused a lower malondialdehyde and proline production in rice genotypes under heat stress. In conclusion, the biostimulants BR, AA, NP, or BE can be considered an agronomic strategy to help mitigate the adverse effects of heat stress in rice areas where periods of high temperatures are expected during the day in Colombia
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