394 research outputs found

    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

    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

    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

    Patterns of language and auditory dysfunction in 6-year-old children with epilepsy

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    In a previous study we reported difficulty with expressive language and visuoperceptual ability in preschool children with epilepsy and otherwise normal development. The present study analysed speech and language dysfunction for each individual in relation to epilepsy variables, ear preference, and intelligence in these children and described their auditory function. Twenty 6-year-old children with epilepsy (14 females, 6 males; mean age 6:5 y, range 6 y–6 y 11 mo) and 30 reference children without epilepsy (18 females, 12 males; mean age 6:5 y, range 6 y–6 y 11 mo) were assessed for language and auditory ability. Low scores for the children with epilepsy were analysed with respect to speech-language domains, type of epilepsy, site of epileptiform activity, intelligence, and language laterality. Auditory attention, perception, discrimination, and ear preference were measured with a dichotic listening test, and group comparisons were performed. Children with left-sided partial epilepsy had extensive language dysfunction. Most children with partial epilepsy had phonological dysfunction. Language dysfunction was also found in children with generalized and unclassified epilepsies. The children with epilepsy performed significantly worse than the reference children in auditory attention, perception of vowels and discrimination of consonants for the right ear and had more left ear advantage for vowels, indicating undeveloped language laterality

    Nitrogen and phosphorus dynamics in plants and soil fertigated with decentralised wastewater treatment effluent

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    Municipalities in South Africa face problems in providing sanitation to unserved informal settlements in peri-urban areas and rural nodes. The Decentralised Wastewater Treatment System (DEWATS) connected to community ablution blocks can be an option, with the treated effluent then applied to agricultural land. However, the management of treated wastewater through irrigation of crops must be environmentally sustainable. This study therefore investigated nitrogen (N) and phosphorus (P) dynamics in soil irrigated with DEWATS effluent. A field study with banana and taro in a randomised complete block design with three blocks and two irrigation treatments (DEWATS effluent without fertiliser vs tap water + fertiliser) was carried out over a period of 992 days at the Newlands-Mashu Research Site, Durban, South Africa. Data were collected on crop N and P uptake, soil chemical properties, and nutrient leaching together with groundwater monitoring. Nitrogen and P uptake was not significantly different (p > 0.05) between the two irrigation treatments. Irrigation with DEWATS effluent increased soil N and P concentrations within the upper 0.3 m implying its importance as a fertiliser source. Leaching of N and P from DEWATS effluent treated plots was comparable to that from the tap water + fertiliser treatments. However, to manage excess water in the soil, practices such as irrigation to meet crop water requirements with room for rainfall and installation of subsurface drainage when possible can be employed.The Water Research Commission, South Africahttp://www.elsevier.com/locate/agwat2020-04-20hj2019Plant Production and Soil Scienc
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