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Search Results: 1 - 10 of 202 matches for " BC Ndukwu "
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Probable functions and remobilisation of calcium oxalates inMusa L.
JO Osuji, BC Ndukwu
African Journal of Biotechnology , 2005,
Abstract: The occurrence and distribution of calcium oxalate crystals were investigated in the young and ageing structures of Musa L. cultivars. The calcium oxalate crystals were tested histochemically and examined using light microscopy. The studies revealed the presence of varying forms of the crystals including intra-amylar, solitary and raphide bundles in the different tissues and organs. Remobilization and redistribution of the crystals were observed following senescence in all the cultivars investigated. The usefulness of these observations in understanding the functions and fate of calcium oxalate crystals in plants are highlighted.
Cytogenetic studies on some Nigerian species of Solanum L. (Solanaceae)
GC Obute, BC Ndukwu, BE Okoli
African Journal of Biotechnology , 2006,
Abstract: Cytogenetic studies to determine the chromosome number, structure and behaviour of some species of Solanum in Nigeria was carried out. Attempt was also made to induce polyploidy in the species. Comparative analysis of the cytological behaviour of the diploid and polyploid cytotypes was made. The studies show that the somatic chromosome number in the genus Solanum is 2n = 24. Colchiploidisation produced tetraploids with 2n = 48 and aneuploids with 2n = 69. The karyotype analysis indicates that the chromosomes were generally very small. There were also slight variations in centromeric positions and arm lengths. Meiotic behaviour of the chromosomes involved a combination of bivalent and multivalent associations especially at the polyploid levels. The significance of this work in the understanding of cytogenetic behaviour of plants and crop improvement efforts are discussed
Cytogenetic studies on some Nigerian species of Solanum L. (Solanaceae)
GC Obute, BC Ndukwu, BE Okoli
African Journal of Biotechnology , 2006,
Abstract: Cytogenetic studies to determine the chromosome number, structure and behaviour of some species of Solanum in Nigeria were carried out. Attempt was also made to induce polyploidy in the species. Comparative analysis of the cytological behaviour of the diploid and polyploid cytotypes was made. The studies show that the somatic chromosome number in the genus Solanum is 2n = 24. Colchiploidisation produced tetraploids with 2n = 48 and aneuploids with 2n = 69. The karyotype analysis indicates that the chromosomes were generally very small. There were also slight variations in centromeric positions and arm lengths. Meiotic behaviour of the chromosomes involved a combination of bivalent and multivalent associations especially at the polyploid levels. The significance of this work in the understanding of cytogenetic behaviour of plants and crop improvement efforts are discussed
Targeted mutagenesis in Vigna unguiculata (L.) Walp. and Cucumeropsis mannii (NAUD) in Nigeria
GC Obute, BC Ndukwu, OF Chukwu
African Journal of Biotechnology , 2007,
Abstract: The mutagenic effects of 0.2% aqueous solution of colchicine on gross and micromophological features of seedlings of Vigna unguiculata (L) Walp. and Cucumeropsis mannii (Naud.) were investigated. Terminal buds of two-week old seedlings were assaulted with 0.2% colchicine by the cotton plug and micro syringe methods and performances were monitored until maturity. Colchicine-treated V. unguicu-lata seedlings were observed to grow slower, had malformed leaves, flowered late and produced less number of seeds per pod than the control. Mean values of features like stomatal indices on both the abaxial and adaxial surfaces, terminal leaflet dimensions and trichome distribution between the treated and control were found to be significantly different. In contrast, treated seedlings of C. mannii flowered and fruited earlier than the case of control material. However, growth was also slowed down by the treatment while features like stomatal indices and trichome distribution were not significantly different. The results here have shown that apart from doubling of chromosomes, colchicine can also be used to induce other mutagenic changes which may be of agronomic utility.
Tracking sexual dimorphism in Telfairia occidentalis Hooker f. (Cucurbitaceae) with morphological and molecular markers
BC Ndukwu, GC Obute, IL Wary-Toby
African Journal of Biotechnology , 2005,
Abstract: Morphological (foliar features) and molecular (DNA fingerprinting) markers were used to characterize sexual dimorphism in Telfairia occidentalis Hook. f. (Cucurbitaceae). A total of thirty strains comprising fifteen males and fifteen females from market-sourced fruits bred to the third generation were used for the investigation. The amplified fragment length polymorphism (AFLP) technique was combined with silver staining to determine the level of DNA polymorphism in the strains. Results showed that the females were generally larger in size than the males in leaf morphological features, while DNA fingerprints revealed the existence of polymorphism in the plant. However, this genetic variability did not clearly correspond with presence of sexual dimorphism in the species. The implications of these results in understanding the genetics, breeding and conservation of the plant’s germplasm are discussed.
Quantitative Safety: Linking Proof-Based Verification with Model Checking for Probabilistic Systems
Ukachukwu Ndukwu
Electronic Proceedings in Theoretical Computer Science , 2009, DOI: 10.4204/eptcs.13.3
Abstract: This paper presents a novel approach for augmenting proof-based verification with performance-style analysis of the kind employed in state-of-the-art model checking tools for probabilistic systems. Quantitative safety properties usually specified as probabilistic system invariants and modeled in proof-based environments are evaluated using bounded model checking techniques. Our specific contributions include the statement of a theorem that is central to model checking safety properties of proof-based systems, the establishment of a procedure; and its full implementation in a prototype system (YAGA) which readily transforms a probabilistic model specified in a proof-based environment to its equivalent verifiable PRISM model equipped with reward structures. The reward structures capture the exact interpretation of the probabilistic invariants and can reveal succinct information about the model during experimental investigations. Finally, we demonstrate the novelty of the technique on a probabilistic library case study.
Oil and Gas Pipeline Construction-Induced Forest Fragmentation and Biodiversity Loss in the Niger Delta, Nigeria  [PDF]
Ikechukwu O. Agbagwa, Benjamin C. Ndukwu
Natural Resources (NR) , 2014, DOI: 10.4236/nr.2014.512061
Abstract: The impacts of oil and gas pipeline construction on the forest and biodiversity in parts of the Niger Delta was investigated. This was achieved by studying the construction activities and operational phases of two pipelines with cumulative length of 165 km vis-à-vis the biodiversity of the affected area. The study involved field sampling along the RoWs to inventorize the fauna and flora, visual assessments and interview with locals. It was observed that the pipelines traversed moist lowland/freshwater swamp and mangrove forests, and barrier islands with approximately 4,950,000 m2 (equivalent of 495 hectares) of forest cleared and 9,642,000 trees killed to realize the pipelines. A total of 219 plant species in 66 families and 125 different fauna species from 64 families were recorded in these areas. Three out of the 4 recorded species of Meliaceae were threatened based on IUCN Conservation Status. Also based on IUCN Conservation Status, 20 mammals, including Pan troglodytes, Cercopithecus erythrogaster and Trichechus senegalensis, 7 birds, 2 reptiles and 1 amphibian were within threatened group. The results showed that the study area had witnessed colossal loss of biodiversity due to habitat displacement, forest fragmentation and deforestation, and escalated exploitation of species. The study identified the most affected biodiversity, and proffered measures to mitigate such occurrences.
Model exploration and analysis for quantitative safety refinement in probabilistic B
Ukachukwu Ndukwu,Annabelle McIver
Electronic Proceedings in Theoretical Computer Science , 2011, DOI: 10.4204/eptcs.55.7
Abstract: The role played by counterexamples in standard system analysis is well known; but less common is a notion of counterexample in probabilistic systems refinement. In this paper we extend previous work using counterexamples to inductive invariant properties of probabilistic systems, demonstrating how they can be used to extend the technique of bounded model checking-style analysis for the refinement of quantitative safety specifications in the probabilistic B language. In particular, we show how the method can be adapted to cope with refinements incorporating probabilistic loops. Finally, we demonstrate the technique on pB models summarising a one-step refinement of a randomised algorithm for finding the minimum cut of undirected graphs, and that for the dependability analysis of a controller design.
An expectation transformer approach to predicate abstraction and data independence for probabilistic programs
Ukachukwu Ndukwu,Annabelle McIver
Electronic Proceedings in Theoretical Computer Science , 2010, DOI: 10.4204/eptcs.28.9
Abstract: In this paper we revisit the well-known technique of predicate abstraction to characterise performance attributes of system models incorporating probability. We recast the theory using expectation transformers, and identify transformer properties which correspond to abstractions that yield nevertheless exact bound on the performance of infinite state probabilistic systems. In addition, we extend the developed technique to the special case of "data independent" programs incorporating probability. Finally, we demonstrate the subtleness of the extended technique by using the PRISM model checking tool to analyse an infinite state protocol, obtaining exact bounds on its performance.
Perseverance: an Indispensable Value for Man’s Success in the Light of Lk. 9:62
BC Udeh
African Research Review , 2010,
Abstract: As a clergy in the missionary field, who has been interacting with people, coupled with the experiences gathered in the institutions of higher learning, it has been observed that many people who are facing many difficult challenges in life, most often despair and surrender. Many people do not know that if they fail in one area, they can still succeed in another. What it means therefore is that one is expected to know one’s target, and do everything within one’s power to hit that target. It is to this effect that Jesus, referring to the kingdom of God as a necessary target, emphatically affirmed that, who ever puts his hands on the plough and looks back, is not fit for the kingdom of God (Luke 9:62). The purpose of this write up therefore is to awaken people’s consciousness on the importance of perseverance in man’s quest for success in life and to urge people to persevere in their struggle for survival. To verify the possibility of hitting ones target through perseverance, the researcher, examined the difficulties experienced by Abraham Lincoln during his journey to the presidential seat of America and Helen killer’s achievements in life in spite of her deformities. It was observed that duo were able to succeed because of their perseverance and tenacity towards the achievement of their set target. The conclusion therefore is that those who have persevered in the pursuit of their set target most often succeeded. It is therefore recommended that everyone should be able to identify ones set target and go for it. Furthermore, people should stop losing hope in the face of difficulties rather, one should get convinced that perseverance and tenacity can give victory to all.
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