434 research outputs found

    On evaluating density driven groundwater flow in the closed basin

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    The hydrogeochemical cycle in the Pilot Valley, a closed basin, is subject to climate variability over a wide range of spatial and temporal scales over long period of time. Saturated and Unsaturated Transport Model (SUTRA) is employed in the Pilot Valley to simulate subsurface and density driven groundwater flow under various climatic and geologic conditions. A Maxey-Eakin method with coupled catchment model, aridity index and incomplete beta function for groundwater recharge distribution is integrated into the SUTRA model for various simulations. A Rayleigh number is used to analyze these circulation patterns of flow under variable climate and geologic conditions. The simulation results, under different groundwater recharge rates, indicate the existence or absence of free convection flow and salt nose movement under the playa and towards hinge line. The simulation result for a historical wet period (12 ka) has a narrow salt nose extent and a historical dry period (6 ka) has a wider salt nose extent. High permeability values generate more free convective cells and low permeability values generate less or eliminate free convective cells in the flow domain. This study will help minimize damage from extreme climatic conditions which occur frequently in the study area and also help manage water resources efficiently

    Arbuscular Mycorrhizas: Producing and Applying Arbuscular Mycorrhizal Inoculum

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    This publication addresses common questions about arbuscular mycorrhiza (AM) fungi and provides information that will enable interested individuals to produce and then evaluate AMF inocula with minimal external assistance

    NREL Pyrheliometer Comparison: September 16 to 27, 2013 (NPC-2013)

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    Accurate measurements of direct normal (beam) solar irradiance from pyrheliometers are important for the development and deployment of solar energy conversion systems, improving our understanding of the Earth's energy budget for climate change studies, and for other science and technology applications involving solar flux. Providing these measurements places many demands on the quality system used by the operator of commercially available radiometers. Maintaining accurate radiometer calibrations traceable to an international standard is the first step in producing research-quality solar irradiance measurements. As with all measurement systems, absolute cavity radiometers and other types of pyrheliometers are subject to performance changes over time. NREL has developed and maintained a group of absolute cavity radiometers with direct calibration traceability to the World Radiometric Reference (WRR). These reference instruments are used by NREL to calibrate pyrheliometers and pyranometers using the ISO 17025 accredited Broadband Outdoor Radiometer Calibration (BORCAL) process (Reda et al. 2008). NPCs are held annually at the Solar Radiation Research Laboratory (SRRL) in Golden, Colorado. Open to all pyrheliometer owners/operators, e.g. NREL, NASA, NIST, NOAA, USA industry and academia, USA-DOE and other national laboratories, and national and international organizations. Each NPC provides an opportunity to determine the unique World Radiometric Reference (WRR) transfer factor (WRR-TF) for each participating pyrheliometer. By adjusting all subsequent pyrheliometer measurements by the appropriate WRR-TF, the solar irradiance data are traceable to the International System of Units through WRR

    Validation of GOES-Derived Surface Radiation Using NOAA's Physical Retrieval Method

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    This report was part of a multiyear collaboration with the University of Wisconsin and the National Oceanic and Atmospheric Administration (NOAA) to produce high-quality, satellite-based, solar resource datasets for the United States. High-quality, solar resource assessment accelerates technology deployment by making a positive impact on decision making and reducing uncertainty in investment decisions. Satellite-based solar resource datasets are used as a primary source in solar resource assessment. This is mainly because satellites provide larger areal coverage and longer periods of record than ground-based measurements. With the advent of newer satellites with increased information content and faster computers that can process increasingly higher data volumes, methods that were considered too computationally intensive are now feasible. One class of sophisticated methods for retrieving solar resource information from satellites is a two-step, physics-based method that computes cloud properties and uses the information in a radiative transfer model to compute solar radiation. This method has the advantage of adding additional information as satellites with newer channels come on board. This report evaluates the two-step method developed at NOAA and adapted for solar resource assessment for renewable energy with the goal of identifying areas that can be improved in the future

    Illness and Treatment Perceptions of Patients with Epilepsy Attending Treatment at a Tertiary Hospital in Addis Ababa – A Qualitative Exploration

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    BACKGROUND: Epilepsy can be a large economic burden in countries where appropriate treatment is not taken due to religious and psychosocial beliefs. The objective of this study was to explore the perceptions and experiences of patients with epilepsy attending their treatment at Tikur Anbessa SpecializedHospital about their illness and treatment.METHODS: A qualitative exploratory design with an in-depth interview was followed. Fourteen purposively selected patients were used until saturation of key emerging themes was achieved.RESULTS: The finding showed that study participants expressed perceptions towards their illness including about its cause, timeline, severity and psychosocial consequences which at times may be considered different from the biomedical version. They also expressed concerns about their treatment, reported aboutsocial and psychological issues and in certain cases dissatisfaction with their healthcare providers. Such issues may have led to delays in treatment-seeking and non-adherence to recommended treatment regimens and as well use of traditional medicine and spiritual healing. On the other hand, reasons that were reported to positively influence their treatment experiences include necessity perceptions about their medications, family support and use of spiritual healing alongside their biomedical treatment.CONCLUSION: The healthcare provision should improve to cater to these groups of patients including instituting chronic care management and appropriate health education provision

    Guide to chicken health and management in Ethiopia: For farmers and development agents

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    Biotechnology and Biological Sciences Research Council, United KingdomDepartment for International Development, United Kingdo

    Genetic Diversity among and within Accessions of a Lablab (\u3ci\u3eLablab purpureus\u3c/i\u3e) Collection Maintained in the ILRI Forage Genebank

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    Lablab (Lablab purpureus L.) is an important annual multi-purpose legume used as a vegetable for human consumption, as forage for livestock, and as green manure and a cover crop to improve soil fertility. It has a high feed value with good digestibility and high crude protein content. The International Livestock Research Institute (ILRI) forage genebank holds a diverse set of 340 lablab accessions collected from different regions of the world. A total of 1,843 plants from 142 lablab accessions (1 to 29 plants per accession genotyped individually) were genotyped by the genotyping-by-sequencing (GBS) method of the DArTseq platform. The genotyping produced a total of 38,824 and 64,793 genome-wide single nucleotide polymorphism (SNP) and SilicoDArT high-density markers, respectively. The short sequence reads corresponding to the markers were mapped on the mungbean (Vigna radiata) reference genome, with approximately 37% of the SNPs and 26 % of the SilicoDArTs able to be mapped. A subset of 1,000 robust markers was filtered by different criteria and used for the diversity analysis. Clustering analysis using the discriminant analysis of principal components (DAPC) detected five major groups, each with further subgroups. Analysis of molecular variance (AMOVA) showed a highly significant (P \u3c 0.00001) variation, explaining more than 73 % of the variance among the accessions. A significant variation (P \u3c 0.005) was also observed among plants within accessions, which explained about 27 % of the variation. The results of this study provide a useful guide for the management and rationalization of activities of the lablab germplasm collection at the ILRI genebank. The substantial genetic diversity observed in the collection reveals the potential of the population for further genetic studies

    Performance of Napier Grass (\u3ci\u3eCenchrus purpureus\u3c/i\u3e L.) Genotypes Grown under Limited Soil Moisture

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    Napier grass (Cenchrus purpureus Schumach L.) is an important perennial forage native to Africa and grown in many tropical and subtropical countries. It is considered as a short-term drought tolerant forage which is a useful trait in areas that are characterized by low precipitation during the dry season. To exploit the potential of this grass and identify water use efficient (WUE) genotypes, a field drought stress trial was conducted at Bishoftu, Ethiopia. Eighty-four Napier grass genotypes were planted in a p-rep design in four replications. The genotypes were evaluated for forage performance during the dry season of 2019 and 2020 based on agro-morphological traits under two soil moisture regimes- moderate water stress (MWS) and severe water stress (SWS). The results indicated the existence of significant diversity among the genotypes for agro-morphological traits and photosynthetic performance. Consistently high biomass producing genotypes with enhanced water use efficiency were observed across harvests in each soil moisture regime, which indicates the possibility of utilizing these genotypes for high biomass production under low soil moisture conditions after further validation in other environments
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