507 research outputs found

    Book Review: \u3ci\u3eGenetic Glass Ceilings: Transgenics for Crop Diversity\u3c/i\u3e By Jonathan Gressel

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    In what is destined to become a classic, Jonathan Grassel’s Genetic Glass Ceiling: Transgenics for Crop Diversity is a carefully crafted book that is firmly rooted in science, engaging and thought-provoking, very bold in its assertions, and yet not overly alarming. Throughout, its author challenges his readers to think outside the box. Cognizant of the fact that genetic engineering as a tool in the plant breeder’s toolkit has its ardent proponents as well as detractors, Grassel, who obviously belongs to the former camp, devotes the first nine chapters to a thorough review of the science, showing how plant breeders are constrained in their work by diminishing genetic diversity, the lifeblood of their trade, and why genetic engineering deserves consideration as the “genetic glass ceiling buster.” The approach adopted in writing this book may be likened to a classic SWOT (strengths-weaknesses-opportunities- threats) analysis of the issues. Classical plant breeding is responsible for the domestication of numerous plant species resulting in highly productive cultivars that form the basis of the world’s food supply. Of the crops that feed the world, the so-called “big four” (corn, wheat, rice, and soybean) have received most attention by breeders, to the extent that a yield plateau has been attained or approached. Classical breeding tools are incapable of breeching what Gressel aptly describes as a genetic glass ceiling to enable more productive and versatile cultivars to be developed to meet ever-increasing world food needs

    The Impact of Managerial Networking Relationships on Organizational Performance in Sub­Saharan Africa: Evidence from Ghana

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    This paper focuses on how managerial networking relationships developed with external entities affect organizational performance using survey data from organizations in Ghana. Networking relationships with external entities are established so as to obtain resources, valuable information, and to acquire and exploit knowledge, in order to overcome the high level of uncertainty in the business environment. The findings provide strong support that managerial networking relationships developed with top managers of other firms, government bureaucratic officials, community leaders, and leaders of employee unions and representatives enhance organizational performance. However, managerial networking relationships developed with politicians at different levels of government are either not related to performance or impede performance. Empirically, the findings confirm that managerial networking relationships may have beneficial as well as detrimental effects on organizations

    Impacts of Postharvest Temperature Exposure Profiles on Rice Physicochemical Properties

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    Heated-air drying followed by tempering (HAT) is effective for increasing rough-rice drying rates without compromising head rice yield (HRY). However, heat exposure could affect rice end-use properties. Hypothesizing that the total amount of heat exposure incurred by rice during heated-air drying determines the trend and magnitude of changes in end-use properties, this dissertation sought to 1) characterize the effects of drying and tempering regimen on changes in end-use properties, 2) derive an index to quantify and compare the amount of heat exposure that rice kernels incur during active drying and, 3) relate values of this index to changes in rice end-use properties. A series of drying experiments were conducted on a long-grain rice cultivar. Paste viscosities and texture of rice gels prepared from flour obtained from dried (12.5% MC) rice samples were evaluated. A theoretical framework was developed and employed alongside time-temperature data collected from drying experiments to derive an index for quantifying thermal exposure, Graham-Acquaah’s Thermal Exposure (GATE) value, during drying. Paste viscosities and gel texture were not only dependent on drying air temperature but also on how long the rice was exposed to a given temperature during drying and tempering. Air relative humidity (rh) had an indirect effect on end-use properties. Using different HAT regimens, peak viscosity was altered by 16%, breakdown by 24%, and setback by \u3e500% compared to control samples. Gel strength was increased by approximately 40% with HAT regimens. The GATE values had strong and significant (

    Part I. Synthesis of homochiral 2-methyl-1-azoniatricyclo(4.4.3.0(1,6))tridecane and 2-methyl-1-azoniatricyclo(4.4.4.0(1,6))tetradecane and their applications in phase transfer catalysis. Part II. Enamines and iminium salts from amido acids.

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    Part I. The synthesis of homochiral 2-methyl-1-azoniatricyclo (4.4.3.0\sp{1,6}) tridecane and 2-methyl-1-azonia-tricyclo (4.4.4.0\sp{1,6}) tetradecane salts 6 and 7 starting from L-glutamic acid and L-alanine respectively and their applications in phase-transfer catalysis are described. The application of these salts in the enantioselective phase-transfer catalyzed cyclopropanation reaction between diethyl bromomalonate and methyl vinyl ketone, 2-chloroacrylonitrile or acrolein gave products in good chemical yields, but the enantiomeric excess of the products was very low. Alkylation reactions with ethyl 2-oxocyclopentanecarboxylate or ethyl 2-oxocyclohexanecarboxylate and allyl bromide proceed to give products in good yields but with very low enantiomeric excess. Possible reasons for these results are discussed. Part II. The synthesis of some N-(ω\omega-carboxyalkyl)lactams and N-(ω\omega-carbethoxyalkyl)lactams and their pyrolysis over soda lime to give enamines are described. This investigation took place as part of a general investigation of the effectiveness of this carbon-carbon bond forming reaction in the synthesis of enamines and iminium salts and the ability to utilize this method in the synthesis of 1-azapropellanes with different ring sizes.Dept. of Chemistry and Biochemistry. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1988 .A363. Source: Dissertation Abstracts International, Volume: 49-04, Section: B, page: 1168. Thesis (Ph.D.)--University of Windsor (Canada), 1988

    Human Capital Availability, Competitive Intensity and Manufacturing Priorities in a Sub-Saharan African Economy

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    Several studies have been done on the relationships between human resources management (HRM) practices and manufacturing activities. However, most of these studies have been confined to well-developed economies where the focus of HRM practices is mostly on the investment in human capital to facilitate the use of advanced manufacturing technology. In less developed economies, the primary HRM concern is attracting and retaining skilled, knowledgeable and experienced labor. In this study, we examine the relationships between human capital availability, competitive intensity and their interactive effects on manufacturing priorities in a Sub-Saharan African economy — Ghana. We found that competitive intensity is an important determinant of the emphasis firms plan to place on manufacturing priorities (low-cost, quality, flexibility, and delivery). However, human capital availability affects the emphasis firms plan to place on low-cost and delivery. Furthermore, competitive intensity moderates the relationship between human capital availability and the emphasis that firms plan to place on the manufacturing priorities of low-cost and quality

    Variations in agronomic and grain quality traits of rice grown under irrigated lowland conditions in West Africa

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    Rice breeding in West Africa has been largely skewed toward yield enhancement and stress tolerance. This has led to the variable grain quality of locally produced rice in the region. This study sought to assess variations in the agronomic and grain quality traits of some rice varieties grown in this region, with a view to identifying sources of high grain yield and quality that could serve as potential donors in their breeding programs. Forty‐five varieties were grown under irrigated conditions in Benin and Senegal with two trials in each country. There were wide variations in agronomic and grain quality traits among the varieties across the trials. Cluster analysis using paddy yield, head rice yield, and chalkiness revealed that 68% of the total variation could be explained by five varietal groupings. One group comprising seven varieties (Afrihikari, BG90‐2, IR64, Sahel 108, WAT311‐WAS‐B‐B‐23‐7‐1, WAT339‐TGR‐5‐2, and WITA 10) had high head rice yield and low chalkiness. Of the varieties in this group, Sahel 108 had the highest paddy yield in three of the four trials. IR64 and Afrihikari had intermediate and low amylose content, respectively, with the rest being high‐amylose varieties. Another group of varieties consisting of B6144F‐MR‐6‐0‐0, C74, IR31851‐96‐2‐3‐2‐1, ITA222, Jaya, Sahel 305, WITA 1, and WITA 2 had high paddy yield but poor head rice yield and chalkiness. The use of materials from these two groups of varieties could accelerate breeding for high yielding rice varieties with better grain quality for local production in West Africa

    Bioactivity of some natural products against the cowpea storage weevil Callosobruchus Maculatus L.

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    This work was carried out to evaluate the insecticidal activity of extracts from 14 plant species of Ghanaian origin against Callosobruchus maculatus adults under laboratory conditions. Phytochemical screenings of the 14 plant species were performed using standard laboratory methods to determine the types of secondary natural products present in the plant species. Aqueous, petroleum ether and ethanolic extracts of the 14 plant species were screened for their bioactivity against Artemia selina in a brine shrimp lethality test. The pesticidal activities of the plant products against Callosobruchus maculatus were investigated in laboratory experiments. Contact toxicity (filter paper impregnation method), grain treatment with plant products for insect population and mortality assays, and also effect of the plant products on grain damage were obtained and compared with Actellic Super EC (synthetic insecticide) during a three-month observation period. Cymbopogan winterianus oil caused the highest mortality, least damage to grains and the highest antireproductive effect. All grain-protective properties of the natural products were concentration and time dependent. Extracts of Cassia alata showed good potential in protecting cowpea and gave better protection than the powder, whilst Griffornia simplicifolia did not significantly protect the grains. Phytochemical investigations of the plants revealed the presence of terpenes, saponins, tannins, glycosides, alkaloids, anthraquinones and flavonoids. The presence of some of these compounds may be responsible for the pesticidal action of the plants.Keywords: Phytochemical screening, Extracts, Insecticidal, Brine shrimp lethality test, Cowpea

    Ethanol sensitivity: a central role for CREB transcription regulation in the cerebellum

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    BACKGROUND: Lowered sensitivity to the effects of ethanol increases the risk of developing alcoholism. Inbred mouse strains have been useful for the study of the genetic basis of various drug addiction-related phenotypes. Inbred Long-Sleep (ILS) and Inbred Short-Sleep (ISS) mice differentially express a number of genes thought to be implicated in sensitivity to the effects of ethanol. Concomitantly, there is evidence for a mediating role of cAMP/PKA/CREB signalling in aspects of alcoholism modelled in animals. In this report, the extent to which CREB signalling impacts the differential expression of genes in ILS and ISS mouse cerebella is examined. RESULTS: A training dataset for Machine Learning (ML) and Exploratory Data Analyses (EDA) was generated from promoter region sequences of a set of genes known to be targets of CREB transcription regulation and a set of genes whose transcription regulations are potentially CREB-independent. For each promoter sequence, a vector of size 132, with elements characterizing nucleotide composition features was generated. Genes whose expressions have been previously determined to be increased in ILS or ISS cerebella were identified, and their CREB regulation status predicted using the ML scheme C4.5. The C4.5 learning scheme was used because, of four ML schemes evaluated, it had the lowest predicted error rate. On an independent evaluation set of 21 genes of known CREB regulation status, C4.5 correctly classified 81% of instances with F-measures of 0.87 and 0.67 respectively for the CREB-regulated and CREB-independent classes. Additionally, six out of eight genes previously determined by two independent microarray platforms to be up-regulated in the ILS or ISS cerebellum were predicted by C4.5 to be transcriptionally regulated by CREB. Furthermore, 64% and 52% of a cross-section of other up-regulated cerebellar genes in ILS and ISS mice, respectively, were deemed to be CREB-regulated. CONCLUSION: These observations collectively suggest that ethanol sensitivity, as it relates to the cerebellum, may be associated with CREB transcription activity

    The impact of climate change on hydropower generation: a case study of Ghana's Akosombo Dam

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    Climate change has become one of the biggest challenges confronting the world’s economic, social and environmental development efforts today. Responses to these challenges normally fall into two broad categories, namely adaptation and mitigation. Drying lakes, dams, rivers, flooding and sea level rises are some of the climate change induced threats facing humanity and their communities. Typically associated with dams is the reduction in the water level due to an increase in temperature. This is affecting energy generation, particularly within the realm of hydropower facilities. It is against this background that this study investigated both the potential and present threats of climate change to hydropower generation using Ghana’s hydropower facilities through a case study of the Akosombo Dam. In achieving this, the study set out four research objectives. To achieve the four research objectives, the study adopted sound scientific approaches including the use of a mixed-method approach to gather both qualitative and quantitative data from five government organisations and some community members living within the Akosombo Dam catchment area. The data were gathered through administering questionnaires, interviews and field observations. The data included both primary and secondary data which were subjected through sound statistical analysis using advanced Excel and “R”. As part of the findings, the research identified the challenge of a “knowledge gap” in climate change related issues amongst significant members of the community. A statistical analysis of the climate data indicated increasing temperature and sporadic rainfall patterns within the vicinity of the Akosombo Dam and its surrounding areas. The data also revealed that there are institutional climate change policies developed by the managers of the Akosombo Dam to manage the Dam and national climate change. These environmental related policies are aimed towards the management of climate change in Ghana. As part of the recommendations, the study recommended that Ghana’s climate change policies should be revised to be attuned to the United Nations Sustainable Development Goals in the tackle against climate change which is aimed to be achieved by the year 2030 To enhance the management of hydropower, the study proposed the use of three novel comprehensive conceptual climate change management adaptation frameworks namely: integration and coordination network framework, adaptation framework of interaction and adaptation framework of outcomes. The study recommended the Volta River Authority to have its own climate change policy and in addition adopt the three novel climate change management adaptation frameworks to manage the Akosombo Dam in the current wave of the climate change effects.Environmental SciencesPh. D. (Environmental Management
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