De-graft Johnson Emmanuel | Kwame Nkrumah University of Science and Technology (original) (raw)

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Papers by De-graft Johnson Emmanuel

Microbial Risk Analysis, 2018

The use of aquaculture is increasing to meet the growing global demand for seafood. However, the ... more The use of aquaculture is increasing to meet the growing global demand for seafood. However, the use of aquaculture for seafood production incurs potential human health risks, especially from enteric bacteria such as Salmonella spp. Salmonella spp. was the most frequently reported cause of outbreaks associated with crustaceans from 1998 to 2004. Among crustacean species, shrimp are the most economically important, internationally traded seafood commodity, and the most commonly aquaculture-raised seafood imported to the United States. To inform safe aquaculture practices, a quantitative microbial risk assessment (QMRA) was performed, incorporating stochastic variability in pathogen growth, industrial shrimp processing, and consumer shrimp preparation. Several scenarios including gamma irradiation and cooking time were considered in order to examine the relative importance of these practices in terms of their impact on risk. Median annual infection risks for all scenarios considered were below 10 −4 and median disability adjusted life year (DALY) metrics were below 10 −6 DALY per person per year, however, 95th percentile risks were above 10 −4 annual probability of infection and 10 −6 DALY per person per year for scenarios with improper cooking and lack of gamma irradiation. The greatest difference between microbiological risks for the scenarios tested was observed when comparing proper vs. improper cooking (5-6 orders of magnitude) and gamma irradiation (4-5 orders of magnitude) compared to (up to less than 1 order of magnitude) for peeling and "deveining" (removing the shrimp digestive tract) vs. peeling only. The findings from this research suggest that restriction of Salmonella spp. to low levels (median 5-30 per L aquaculture pond water) may be necessary for scenarios in which proper downstream food handling and processing cannot be guaranteed. internationally traded seafood commodity (Amagliani et al., 2012). Moreover, penaeid shrimps are the most commercially important species of farmed shrimp globally (FAO, 2016; Farfante, 1988; Moss et al., 2012). Penaeus vannamei, whiteleg shrimp, have been effectively grown in multiple states in the US,

Applied Soil Ecology, 2018

Reliable information on the persistence of rhizobium in soil in the absence of host between growi... more Reliable information on the persistence of rhizobium in soil in the absence of host between growing periods is important in deciding whether inoculation on the same plot in subsequent seasons is necessary. This study determined the survival of introduced rhizobium strains and predominant factors that influence the declining rates of their populations. Bradyrhizobium yuanmingense (BR 3267) and B. japonicum (USDA 110) were manually incorporated into soils at four different locations (Kpalga, Tanina, Tunayilli and Busa) in northern Ghana at 2.5 × 10 8 (log 10 8.4) and 2.5 × 10 7 (log 10 7.4) cells g −1 peat, respectively, per 6 m 2. The populations of surviving cells were estimated at 0, 21, 42, 81, 142 and 296 days using the Most Probable Number (MPN) count technique. Several decline functions were applied to the data with hyperbolic regression function emerging as the option that provides the best fit for B. yuanmingense strain BR 3267 and B. japonicum strain USDA 110 at all locations. There was no significant difference in the declining rates between the different locations; however, there were differences in the declining rates for the sampling times. At 296 days, the numbers of surviving cells of B. yuanmingense strain BR 3267 and B. japonicum strain USDA 110 were log 10 1.9 and log 10 1.7, respectively. Native rhizobium population and soil moisture were the predominant factors that affected the survival of the introduced strains. It is evident from the studies that these strains can survive in sufficient numbers at least within a year; therefore, re-inoculation may not be necessary for a following season especially when using B. yuanmingense strain BR 3267.

Communications in Mathematics and Statistics, 2016

Sometimes, people with interest in measuring quality of education take into account level in acad... more Sometimes, people with interest in measuring quality of education take into account level in academic performance and various associated factors. Usually, an average academic performance is an accustomed way of assessment; however, this study examines on individual basis different factors that might have an impact on the academic performance of undergraduate students. Data on the semester weighted average of class of 2012 mathematics students were acquired from the Quality Assurance and Planning Unit and the

A thesis submitted to the Department of Mathematics in partial fulfillment of the requirement for... more A thesis submitted to the Department of Mathematics in partial fulfillment of the requirement for the award of the degree of Doctor of Philosophy in Mathematical Statistics, 2015

European Journal of Pure and Applied Mathematics, 2018

In this paper, we introduce the proofs of product inequalities:u v ≤ u + v , for all u, v ∈ [0, 2... more In this paper, we introduce the proofs of product inequalities:u v ≤ u + v , for all u, v ∈ [0, 2], and u + v ≤ u v , for allu, v ∈ [2, ∞). The first product inequality u v ≤ u + v holds forany two vectors in the interval [0, 1] in Holder’s space and also valid anytwo vectors in the interval [1, 2] in the Euclidean space. On the otherhand, the second product inequality u + v ≤ u v ∀u, v ∈ [2, ∞)only in Euclidean space. By applying the first product inequality to theL p spaces, we observed that if f : Ω → [0, 1], and g : Ω → R, thenf p g p ≤ f p + g p . Also, if f, g : Ω → R, then f p + g p ≤f p g p .

Microbial Risk Analysis, 2018

The use of aquaculture is increasing to meet the growing global demand for seafood. However, the ... more The use of aquaculture is increasing to meet the growing global demand for seafood. However, the use of aquaculture for seafood production incurs potential human health risks, especially from enteric bacteria such as Salmonella spp. Salmonella spp. was the most frequently reported cause of outbreaks associated with crustaceans from 1998 to 2004. Among crustacean species, shrimp are the most economically important, internationally traded seafood commodity, and the most commonly aquaculture-raised seafood imported to the United States. To inform safe aquaculture practices, a quantitative microbial risk assessment (QMRA) was performed, incorporating stochastic variability in pathogen growth, industrial shrimp processing, and consumer shrimp preparation. Several scenarios including gamma irradiation and cooking time were considered in order to examine the relative importance of these practices in terms of their impact on risk. Median annual infection risks for all scenarios considered were below 10 −4 and median disability adjusted life year (DALY) metrics were below 10 −6 DALY per person per year, however, 95th percentile risks were above 10 −4 annual probability of infection and 10 −6 DALY per person per year for scenarios with improper cooking and lack of gamma irradiation. The greatest difference between microbiological risks for the scenarios tested was observed when comparing proper vs. improper cooking (5-6 orders of magnitude) and gamma irradiation (4-5 orders of magnitude) compared to (up to less than 1 order of magnitude) for peeling and "deveining" (removing the shrimp digestive tract) vs. peeling only. The findings from this research suggest that restriction of Salmonella spp. to low levels (median 5-30 per L aquaculture pond water) may be necessary for scenarios in which proper downstream food handling and processing cannot be guaranteed. internationally traded seafood commodity (Amagliani et al., 2012). Moreover, penaeid shrimps are the most commercially important species of farmed shrimp globally (FAO, 2016; Farfante, 1988; Moss et al., 2012). Penaeus vannamei, whiteleg shrimp, have been effectively grown in multiple states in the US,

Applied Soil Ecology, 2018

Reliable information on the persistence of rhizobium in soil in the absence of host between growi... more Reliable information on the persistence of rhizobium in soil in the absence of host between growing periods is important in deciding whether inoculation on the same plot in subsequent seasons is necessary. This study determined the survival of introduced rhizobium strains and predominant factors that influence the declining rates of their populations. Bradyrhizobium yuanmingense (BR 3267) and B. japonicum (USDA 110) were manually incorporated into soils at four different locations (Kpalga, Tanina, Tunayilli and Busa) in northern Ghana at 2.5 × 10 8 (log 10 8.4) and 2.5 × 10 7 (log 10 7.4) cells g −1 peat, respectively, per 6 m 2. The populations of surviving cells were estimated at 0, 21, 42, 81, 142 and 296 days using the Most Probable Number (MPN) count technique. Several decline functions were applied to the data with hyperbolic regression function emerging as the option that provides the best fit for B. yuanmingense strain BR 3267 and B. japonicum strain USDA 110 at all locations. There was no significant difference in the declining rates between the different locations; however, there were differences in the declining rates for the sampling times. At 296 days, the numbers of surviving cells of B. yuanmingense strain BR 3267 and B. japonicum strain USDA 110 were log 10 1.9 and log 10 1.7, respectively. Native rhizobium population and soil moisture were the predominant factors that affected the survival of the introduced strains. It is evident from the studies that these strains can survive in sufficient numbers at least within a year; therefore, re-inoculation may not be necessary for a following season especially when using B. yuanmingense strain BR 3267.

Communications in Mathematics and Statistics, 2016

Sometimes, people with interest in measuring quality of education take into account level in acad... more Sometimes, people with interest in measuring quality of education take into account level in academic performance and various associated factors. Usually, an average academic performance is an accustomed way of assessment; however, this study examines on individual basis different factors that might have an impact on the academic performance of undergraduate students. Data on the semester weighted average of class of 2012 mathematics students were acquired from the Quality Assurance and Planning Unit and the

A thesis submitted to the Department of Mathematics in partial fulfillment of the requirement for... more A thesis submitted to the Department of Mathematics in partial fulfillment of the requirement for the award of the degree of Doctor of Philosophy in Mathematical Statistics, 2015

European Journal of Pure and Applied Mathematics, 2018

In this paper, we introduce the proofs of product inequalities:u v ≤ u + v , for all u, v ∈ [0, 2... more In this paper, we introduce the proofs of product inequalities:u v ≤ u + v , for all u, v ∈ [0, 2], and u + v ≤ u v , for allu, v ∈ [2, ∞). The first product inequality u v ≤ u + v holds forany two vectors in the interval [0, 1] in Holder’s space and also valid anytwo vectors in the interval [1, 2] in the Euclidean space. On the otherhand, the second product inequality u + v ≤ u v ∀u, v ∈ [2, ∞)only in Euclidean space. By applying the first product inequality to theL p spaces, we observed that if f : Ω → [0, 1], and g : Ω → R, thenf p g p ≤ f p + g p . Also, if f, g : Ω → R, then f p + g p ≤f p g p .