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Search Results: 1 - 10 of 11272 matches for " Matthew Blair "
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Quantification of drought tolerance in Ethiopian common bean varieties  [PDF]
Asrat Asfaw, Matthew W. Blair
Agricultural Sciences (AS) , 2014, DOI: 10.4236/as.2014.52016

Understanding the level of drought tolerance of the varieties available in each country is of paramount importance for breeding common bean for drought adaptation. The goal of this study was to evaluate 25 common bean genotypes of which 24 were released/recommended varieties for production by farmers and one was a drought tolerant check. The genotypes were planted at two sites in Ethiopia, Hawasssa and Amaro, using variable sowing dates, one that was early to avoid drought and one that was late to expose the crop to drought. The experiments were repeated over two years in Hawassa and one year in Amaro. This resulted in treatments with high and low total seasonal rainfall and six environments for analysis. The impact of drought stress on the trait expression of the varieties was not uniform across traits assessed and varieties tested. The effect of drought on photosynthate translocation and partitioning traits was much greater than on yield component traits in the varieties studied. This indicating less breeding efforts has been made in improving the varieties ability to mobilize photosynthate to the developing grain as compared to the yield component traits. Drought tolerant varieties like Hawassa Dume maintained better photosynthate translocation and partitioning than the drought sensitive varieties like Brown Speckled bean. Hawassa Dume also showed better yield stability and performed well under both drought stress and nonstress conditions. Our results indicate the relevance of high levels of photosynthate translocation and partitioning as an effective selection objective for improving drought tolerance in common bean. The information generated on the drought tolerance of the available varieties should help in the design of a breeding strategy that incorporates adaptation traits with commercial characteristics preferred by common bean farmers for varieties to be grown in diverse environments.

Effects of Moisture Deficit on the Yield of Cowpea Genotypes in the Guinea Savannah of Northern Ghana  [PDF]
Damba Yahaya, Nicholas Denwar, Matthew W. Blair
Agricultural Sciences (AS) , 2019, DOI: 10.4236/as.2019.104046
Abstract: Cowpea is multipurpose, leguminous, high protein crop in the tropics that provides food for humans and fodder for animals. The crop adds nitrogen and other nutrients to the soil through symbiotic relationship with rhizobia and direct decomposition of cowpea by-products. Despite its multiple benefits for humankind, the yield of cowpea is far below its potential and its production in the crop’s birthplace of Africa is especially affected by abiotic factors. Soil moisture deficit is one of the main abiotic factors that affect the yield of cowpea in the semi-arid tropics, including the Sahelian and Guinea Savannah regions in West Africa. Even though cowpea is a drought tolerant legume, different genotypes respond differently to drought, resulting in up to 100% or more yield increases in the case of resistant genotypes or 50% or more yield loss in case of susceptible types. Mitigating the effect of soil moisture deficit on cowpea production requires selection of genotypes that can withstand drought. With this in mind, the goal of this study was to identify drought tolerant cowpea germplasm for the Savannah region of Northern Ghana using cultivated genotypes from the United States Department of Agriculture (USDA) tested with and without irrigation at the Bontanga irrigation facility during the dry season in 2018. Fifty genotypes were used, which included 45 imported from USDA and five (5) local genotypes from the Savannah Agriculture Research Institute (SARI). The experiment had 2 × 50 factorial treatments (irrigation × genotypes) and consisted of randomized complete block design with three (3) replications per treatment. Two (2) watering regimes were introduced namely, drought stressed (no irrigation) and non-stressed/control (irrigated). Morpho-physiological, phenological and yield data were taken on the cowpeas evaluated with drought tolerance assessed based on grain yield data and derived indices. All parameters measured showed significant differences (p ≤ 0.05) except for the number of branches per plant. Genotypes PI339600, PI527263, PI527302, PI582793, PI582867 and SARI-6-2-6 produced high grain yields under both drought stress and non-stress conditions. These genotypes could be exploited for future breeding programs for developing drought tolerant cowpea varieties for the savannah ecology and other areas with similar environmental conditions.
Strichartz and Localized Energy Estimates for the Wave Equation in Strictly Concave Domains
Matthew D. Blair
Mathematics , 2014,
Abstract: We prove localized energy estimates for the wave equation in domains with a strictly concave boundary when homogeneous Dirichlet or Neumann conditions are imposed. By restricting the solution to small, frequency dependent, space time collars of the boundary, it is seen that a stronger gain in regularity can be obtained relative to the usual energy estimates. Mixed norm estimates of Strichartz and square function type follow as a result, using the energy estimates to control error terms which arise in a wave packet parametrix construction. While the latter estimates are not new for Dirichlet conditions, the present approach provides an avenue for treating these estimates when Neumann conditions are imposed. The method also treats Schr\"odinger equations with time independent coefficients.
$L^q$ bounds on restrictions of spectral clusters to submanifolds for low regularity metrics
Matthew D. Blair
Mathematics , 2012,
Abstract: We prove $L^q$ bounds on the restriction of spectral clusters to submanifolds in Riemannian manifolds equipped with metrics of $C^{1,\alpha}$ regularity for $0 \leq \alpha \leq 1$. Our results allow for Lipschitz regularity when $\alpha =0$, meaning they give estimates on manifolds with boundary. When $0< \alpha \leq 1$, the scalar second fundamental form for a codimension 1 submanifold can be defined, and we show improved estimates when this form is negative definite. This extends results of Burq-G\'erard-Tzvetkov and Hu to manifolds with low regularity metrics.
On refined local smoothing estimates for the Schr?dinger equation in exterior domains
Matthew D Blair
Mathematics , 2011,
Abstract: We consider refinements of the local smoothing estimates for the Schr\"odinger equation in domains which are exterior to a strictly convex obstacle in $\RR^n$. By restricting the solution to small, frequency dependent collars of the boundary, it is expected that taking its square integral in space-time should exhibit a larger gain in regularity when compared to the usual gain of half a derivative. By a result of Ivanovici, these refined local smoothing estimates are satisfied by solutions in the exterior of a ball. We show that when such estimates are valid, they can be combined with wave packet parametrix constructions to yield Strichartz estimates. This provides an avenue for obtaining these bounds when Neumann boundary conditions are imposed.
Voltage profile generation for simultaneous multi-protein detection in western blot analysis  [PDF]
Matthew Blair, Mina Wanis, Gaurav Swarnkar, Hiroki Yokota, Stanley Chien
Journal of Biomedical Science and Engineering (JBiSE) , 2012, DOI: 10.4236/jbise.2012.59067
Abstract: Western blotting is a popular technique for examining expression levels of proteins using gel-based electrophoretic fractionation followed by blotting and antibody reactions. Although this is a mature technique, one of the major limitations is the need to prepare an individual electrophoretic gel for each of the protein species to be analyzed. Since most analyses require the detection of multiple protein species, a procedure that allows utilization of a single gel for detecting multiple protein species should significantly save time and resources. In this paper, we developed a novel multiprotein detection device, which enabled simultaneous detection of several proteins species from a single electrophoretic gel. In this device, a protein transfer unit utilized a multi-anode plate that generated a non-uniform voltage profile. This voltage profile enabled uniform transfer regardless of molecular mass of proteins. In vitro experiments using samples, isolated from boneforming osteoblast cells, showed that the expression levels of 5 - 7 different proteins were detectable in the presence and absence of mechanical stimulation that activated genes necessary for bone formation. The result supports the notion that through simultaneous detection of multiple protein species, the described device contributes to reduction in procedural time and sample amounts, as well as a removal of variations among multiple gels.
Screening Cowpea (Vigna unguiculata (L.) Walp.) Genotypes for Enhanced N2 Fixation and Water Use Efficiency under Field Conditions in Ghana  [PDF]
Damba Yahaya, Nicholas Denwar, Mustapha Mohammed, Matthew W. Blair
American Journal of Plant Sciences (AJPS) , 2019, DOI: 10.4236/ajps.2019.104047
Abstract: To explore the variations in symbiotic N2 fixation and water use efficiency in cowpea, this study evaluated 25 USDA cowpea genotypes subjected to drought under field conditions at two locations (Kpachi and Woribogu) in the Northern region of Ghana. The 15N and 13C natural abundance techniques were respectively used to assess N2 fixation and water use efficiency. The test genotypes elicited high symbiotic dependence in association with indigenous rhizobia, deriving between 55% and 98% of their N requirements from symbiosis. Consequently, the amounts of N-fixed by the genotypes showed remarkable variations, with values ranging from 37 kg·N-fixed·ha-1 to 337 kg·N-fixed·ha-1. Most genotypes elicited contrasting symbiotic performance between locations, a finding that highlights the effect of complex host/soil microbiome compatibility on the efficiency of the cowpea-rhizobia symbiosis. The test genotypes showed marked variations in water use efficiency, with most of the genotypes recording higher δ13C values when planted at Kpachi. Despite the high symbiotic dependence, the grain yield of the test cowpeas was low due to the imposed drought, and ranged from 56 kg/ha to 556 kg/ha at Kpachi, and 143 kg/ha to 748 kg/ha at Woribogu. The fact that some genotypes could grow and produce grain yields of 627
Contenido de hierro y cinc en la semilla y su respuesta al nivel de fertilización con fósforo en 40 variedades de fríjol colombianas
Astudillo,Carolina; Blair,Matthew W.;
Agronomía Colombiana , 2008,
Abstract: the improvement of beans in colombia has produced a large number of varieties for different agro-ecological zones and with different adaptation ranges. the objective of this research was to determine the nutritional quality of common bean genotypes from colombia in terms of iron and zinc content of the seed and to determine how soil fertilization with high or low levels of phosphorus impact yield with these minerals . a total of 40 genotypes were evaluated including released varieties from ica or corpoica (of the diacol or ica series), traditional landrace varieties from valle, nari?o and norte de santander, and ciat breeding lines as control. these were planted in darién in the first semester of 2004 under two-fertilization treatments in complete randomized block experiments with three repetitions. iron and zinc content was measured in harvested seed using the spectrophotometric method of atomic absorption. variance analysis showed significant differences for mineral content among genotypes, and between high and low phosphorus fertilization levels with averages of 61.5 and 53.2 ppm for iron and 26.3 and 23.1 for zinc, respectively. given these results, phosphorus fertilization can increase iron content in bean seeds, but can reduce zinc content in seeds.
Contenido de hierro y cinc en la semilla y su respuesta al nivel de fertilización con fósforo en 40 variedades de fríjol colombianas
Astudillo Carolina,Blair Matthew W.
Agronomía Colombiana , 2008,
Abstract: El mejoramiento del fríjol en Colombia ha producido un amplio número de variedades para diferentes zonas agroecológicas y con diferentes rangos de adaptación. Los objetivos de esta investigación fueron determinar la calidad nutricional del fríjol en Colombia en cuanto al contenido de hierro y cinc en el grano y entender cómo los niveles de fertilización del suelo alta y baja en fósforo afectan tanto el rendimiento como el nivel de estos minerales. Se evaluaron 40 genotipos arbustivos dentro de los que se encuentran variedades liberadas por el ICA o Corpoica (series Diacol e ICA), cultivares tradicionales de los departamentos de Valle, Nari o, Norte de Santander, y líneas CIAT como testigos. Estos se sembraron en la localidad de Darién en el primer semestre de 2004, en los dos tratamientos de fertilización, con dise o de bloques completos aleatorizados con tres repeticiones. El contenido de hierro y cinc en la semilla cosechada fue determinado por espectroscopia de absorción atómica. El análisis de varianza mostró diferencias significativas para la concentración de los minerales entre las variedades y entre los niveles de alta y baja fertilización con fósforo con promedios de 61,5 y 53,2 ppm, respectivamente, para hierro, y 26,3 y 23,1 ppm, respectivamente, para cinc. Teniendo en cuenta el análisis combinado para hierro y cinc a través de los dos tratamientos de fósforo, se sugiere que la aplicación de fósforo puede incrementar la concentración de hierro en la semilla, pero no la de cinc.
The Projected Gross-Pitaevskii Equation for harmonically confined Bose gases
P. Blair Blakie,Matthew J. Davis
Physics , 2004, DOI: 10.1103/PhysRevA.72.063608
Abstract: We extend the Projected Gross Pitaevskii equation formalism of Davis et al. [Phys. Rev. Lett. \bf{87}, 160402 (2001)] to the experimentally relevant case of harmonic potentials. We outline a robust and accurate numerical scheme that can efficiently simulate this system. We apply this method to investigate the equilibrium properties of a harmonically trapped three-dimensional Bose gas at finite temperature, and consider the dependence of condensate fraction, position and momentum distributions, and density fluctuations on temperature. We apply the scheme to simulate an evaporative cooling process in which the preferential removal of high energy particles leads to the growth of a Bose-Einstein condensate. We show that a condensate fraction can be inferred during the dynamics even in this non-equilibrium situation.
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