780 research outputs found

    Determining Irrigation Depths for Soybean Using a Simulation Model of Water Flow and Plant Growth and Weather Forecasts

    Get PDF
    A new scheme to determine irrigation depths using a two-point of predicted cumulative transpiration over irrigation interval is presented. Rather than maximizing water use efficiency, this scheme aims to maximize net income. The volumetric water price is considered to give farmers an incentive to save irrigation water. A field experiment for soybeans was carried out in the Arid Land Research Center, Tottori University, Japan in 2019. The total irrigation amount yield and net income by the proposed scheme were compared to those by a tensiometer-operated automated irrigation. The scheme could save irrigation water by 16% with a yield increment of 20%; resulting in a 22% increase in net income compared to the automated irrigation. The model simulated the volumetric water content in the effective root zone of the plant in fair agreement. These results indicate the effectiveness of the proposed scheme that may replace an automated irrigation system even considering uncertainty in weather forecast to determine irrigation depth and secure investment costs

    H(II) centers in natural silica under repeated UV laser irradiations

    Full text link
    We investigated the kinetics of H(II) centers (=Ge'-H) in natural silica under repeated 266nm UV irradiations performed by a Nd:YAG pulsed laser. UV photons temporarily destroy these paramagnetic defects, their reduction being complete within 250 pulses. After re-irradiation, H(II) centers grow again, and the observed recovery kinetics depends on the irradiation dose; multiple 2000 pulses re-irradiations induce the same post-irradiation kinetics of H(II) centers after each exposure cycle. The analysis of these effects allows us to achieve a deeper understanding of the dynamics of the centers during and after laser irradiation.Comment: Submitted to Journal of Non Crystalline Solid

    A new scheme to optimize irrigation depth using a numerical model of crop response to irrigation and quantitative weather forecasts

    Get PDF
    Irrigation management can be improved by utilizing advances in numerical models of water flow in soils that can consider future rainfall by utilizing data from weather forecasts. Toward this end, we developed a numerical scheme to determine optimal irrigation depth on scheduled irrigation days based on a concept of virtual net income as a function of cumulative transpiration over each irrigation interval; this scheme combines a numerical model of crop response to irrigation and quantitative weather forecasts. To evaluate benefits, we compared crop growth and net income of this proposed scheme to those of an automated irrigation method using soil water sensors. Sweet potato (Ipomoea batatas (L.), cv. Kintoki) was grown in 2016 in a sandy field of the Arid Land Research Center, Tottori University, Japan under either a non-optimized automated irrigation or the proposed scheme. Under the proposed scheme, 18% less water was applied, yield increased by 19%, and net income was increased by 25% compared with the results of the automated irrigation system. In addition, soil water content simulated by the proposed scheme was in fair agreement with observed values. Thus, it was shown that the proposed scheme may enhance net income and be a viable alternative for determining irrigation depths

    A quantitative model for IcR product in d-wave Josephson junctions

    Get PDF
    We study theoretically the Josephson effect in d-wave superconductor / diffusive normal metal /insulator/ diffusive normal metal/ d-wave superconductor (D/DN/I/DN/D) junctions. This model is aimed to describe practical junctions in high-TCT_C cuprate superconductors, in which the product of the critical Josephson current (ICI_C) and the normal state resistance (RR) (the so-called ICRI_{\rm C}R product) is very small compared to the prediction of the standard theory. We show that the ICRI_{\rm C}R product in D/DN/I/DN/D junctions can be much smaller than that in d-wave superconductor / insulator / d-wave superconductor junctions and formulate the conditions necessary to achieve large ICRI_{\rm C}R product in D/DN/I/DN/D junctions. The proposed theory describes the behavior of ICRI_{\rm C}R products quantitatively in high-TCT_{\rm C} cuprate junctions.Comment: 4 pages, 6 figure

    Optimization of Irrigation and Leaching Depths Considering the Cost of Water Using WASH_1D/2D Models

    Get PDF
    Optimization of water use with consideration of salinity control is a crucial task for crop production. A new scheme, “optimized irrigation”, was recently presented to determine irrigation depth using WASH_1D/2D which are numerical simulation models of water flow and solute transport in soils and crop growth. In the scheme, irrigation depth is determined such that net income is maximized considering the price of water and weather forecasts. To evaluate whether the optimized irrigation is also able to restrict salinity stress and avoid salinization without any intentional leaching, we carried out a numerical experiment for winter wheat grown in northern Sudan under the following scenarios: (1) Available water in the root zone is refilled using freshwater (0.17 g/L of NaCl) at every five days; (2) available water in the root zone is refilled using saline water (1.7 g/L) at every five days; (3) optimized irrigation using fresh water at 7-days interval; (4) optimized irrigation on a weekly basis using saline water; and (5) same as scenario 2, except for leaching is carried out at the middle of the growing season and leaching depth is optimized such that net income is maximized. The results showed that the optimized irrigation scheme automatically instructs additional water required for leaching at each irrigation event and maximizes the net income even under saline conditions

    Experimental observation of the crystallization of a paired holon state

    Full text link
    A new excitation is observed at 201 meV in the doped-hole ladder cuprate Sr14_{14}Cu24_{24}O41_{41}, using ultraviolet resonance Raman scattering with incident light at 3.7 eV polarized along the direction of the rungs. The excitation is found to be of charge nature, with a temperature independent excitation energy, and can be understood via an intra-ladder pair-breaking process. The intensity tracks closely the order parameter of the charge density wave in the ladder (CDWL_L), but persists above the CDWL_L transition temperature (TCDWLT_{CDW_L}), indicating a strong local pairing above TCDWLT_{CDW_L}. The 201 meV excitation vanishes in La6_{6}Ca8_{8}Cu24_{24}O41+δ_{41+\delta}, and La5_{5}Ca9_{9}Cu24_{24}O41_{41} which are samples with no holes in the ladders. Our results suggest that the doped holes in the ladder are composite bosons consisting of paired holons that order below TCDWT_{CDW}.Comment: Accepted for publication in Physical Review Letters (4 figures

    Bancroftian filariasis in Kwale District, Kenya

    Get PDF
    Objective: To determine the prevalence of Wuchereria bancrofti infection in an area designated for filariasis control trial.Design: A cross-sectional survey.Setting: Three villages in Kinango location, Kwale district, Coast Province, Kenya.Subjects/participants: Oral informed consent to participate was obtained from adults and parents or guardians of children below fifteen years of age.Main outcome measures: Microfilaraemia prevalences, microfilarial densities and clinical manifestations.Results: The overall prevalence of microfilaraemia in the population was 16.4%. The prevalence of microfilaraemia was age-dependent and the overall microfilarial density (MFD) was 69.4 mf/ml (geometric mean) and significantly higher in males (95.8 mf/ml) than in females (48.6 mf/ml) (p < 0.05). The prevalence of clinical signs of infection was also agedependent with elephantiasis being significantly higher in females (2.3%) than in males (0.9%) (p < 0.05). Among the males, the major clinical manifestation was hydrocele (10.4%).Conclusion: These findings show high prevalence of bancroftian filariasis in Kwale district and warrant similar studies followed by implementation of intervention measures to reduce transmission in all areas of endemicity in the Coast Province
    corecore