EXPLORATION OF LIGNIN-BASED SUPERABSORBENT POLYMERS (HYDROGELS) FOR SOIL WATER MANAGEMENT AND AS A CARRIER FOR DELIVERING RHIZOBIUM SPP.

Superabsorbent polymers (hydrogels) as soil amendments may improve soil hydraulic properties and act as carrier materials beneficial to soil microorganisms. Researchers have mostly explored synthetic hydrogels which may not be environmentally sustainable. This dissertation focused on the development and application of lignin-based hydrogels as sustainable soil amendments. This dissertation also explores the development of pedotransfer transfer functions (PTFs) for predicting saturated hydraulic conductivity using statistical and machine learning methods with a publicly available large data set. A lignin-based hydrogel was synthesized, and its impact on soil water retention was determined in silt loam and loamy fine sand soils. Hydrogel treatment significantly increased water retention at saturation/near saturation by 0.12 cm3 cm-3 and at field capacity by 0.08 cm3 cm-3 for silt loam soil compared to a control treatment with no added lignin hydrogel. Hydrogel application significantly increased water retention at -3 cm to -15,000 cm soil water pressure head by 0.01 - 0.03 cm3 cm-3 for the loamy fine sand soil. Calculations demonstrated that at a 1% (w/w) concentration or lower, lignin-based hydrogels in silt loam and loamy fine sand soils would not increase plant available soil water storage. The incorporation of lignin-hydrogels significantly decreased saturated hydraulic conductivity. In unsaturated conditions, application of the lignin-based hydrogel at 0.1 and 0.3% (w/w) increased hydraulic conductivity. New pedotransfer functions (PTFs) for predicting saturated hydraulic conductivity were developed using machine learning (ML) and a large public database. Random forest regression and gradient boosted regression both gave the best performances with R2 =0.71 and RMSE = 0.47 cm h-1 on the validation data set. The concentration of lignin-alginate hydrogel added to Rhizobial cell culture did not affect cell survival. All treatments of wet bioencapsulated beads achieved a similar yield of 97%, however, the presence of starch in the lignin-alginate beads increased the survival of Rhizobium cells

Molecular genotyping in a malaria treatment trial in Uganda - unexpected high rate of new infections within 2 weeks after treatment.

Polymerase chain reaction (PCR) genotyping of malaria parasites in drug efficacy trials helps differentiate reinfections from recrudescences. A combination therapy trial of one (n = 115) or three (n = 117) days artesunate (1AS, 3AS 4 mg/kg/day) plus sulphadoxine-pyrimethamine (SP) vs. SP alone (n = 153) was conducted in Mbarara, a mesoendemic area of western Uganda. All paired recurrent Plasmodium falciparum parasitaemias on days 7, 14, 21 and 28 post-treatment were genotyped by PCR amplification and analysis of glutamate-rich protein (glurp) and merozoite surface proteins (msp) 1 and 2 genes to distinguish recrudescent from new infections. A total of 156 (1AS = 61, 3AS = 35, SP alone = 60) of 199 paired recurrent samples were successfully analysed and were resolved as 79 recrudescences (1AS = 32, 3AS = 8, SP = 39) and 77 as new infections (1AS = 29, 3AS = 27, SP = 21). The ratios of proportions of new to recrudescent infections were 0.2, 0.9, 1.4 and 1.9 on days 7, 14, 21 and 28, respectively (P < 0.001, chi(2) test for linear trend). Unexpected high new infection rates were observed early in follow-up on days 7 [5/26 (19.2%)] and 14 [24/51 (47.1%)]. These results impact significantly on resistance monitoring and point to the value of genotyping all recurrent infections in antimalarial trials

Machine Learning Approach to Simulate Soil CO\u3csub\u3e2\u3c/sub\u3e Fluxes under Cropping Systems

With the growing number of datasets to describe greenhouse gas (GHG) emissions, there is an opportunity to develop novel predictive models that require neither the expense nor time required to make direct field measurements. This study evaluates the potential for machine learning (ML) approaches to predict soil GHG emissions without the biogeochemical expertise that is required to use many current models for simulating soil GHGs. There are ample data from field measurements now publicly available to test new modeling approaches. The objective of this paper was to develop and evaluate machine learning (ML) models using field data (soil temperature, soil moisture, soil classification, crop type, fertilization type, and air temperature) available in the Greenhouse gas Reduction through Agricultural Carbon Enhancement network (GRACEnet) database to simulate soil CO2 fluxes with different fertilization methods. Four machine learning algorithms—K nearest neighbor regression (KNN), support vector regression (SVR), random forest (RF) regression, and gradient boosted (GB) regression—were used to develop the models. The GB regression model outperformed all the other models on the training dataset with R2 = 0.88, MAE = 2177.89 g C ha−1 day−1, and RMSE 4405.43 g C ha−1 day−1. However, the RF and GB regression models both performed optimally on the unseen test dataset with R2 = 0.82. Machine learning tools were useful for developing predictors based on soil classification, soil temperature and air temperature when a large database like GRACEnet is available, but these were not highly predictive variables in correlation analysis. This study demonstrates the suitability of using tree-based ML algorithms for predictive modeling of CO2 fluxes, but no biogeochemical processes can be described with such models

Age of Menarche among basic level school girls in Madina, Accra

The current study was designed to determine the age at which menarche occurs among school girls in Madina, Accra. A survey was conducted among 529 girls selected using multi-stage sampling from basic schools in Madina, Accra. Respondents completed a questionnaire that recorded age-at-first menstruation by recall, household characteristics, and anthropometry. Mean age at menarche was 12.74 + 1.15 years; probit analysis yielded a median age of 12.09 years. Menarcheal age was significantly correlated with current age (r=0.48; p&lt;0.01). Most girls (90%) had first menstruation before age 13. Their mothers' mean age at menarche was 13.6 + 1.08 years. In a multivariate linear regression model, household wealth (p&lt;0.01) and body mass index (p&lt;0.01) were the main modifiable independent predictors of age at onset of menarche. School girls in Madina attained menarche earlier than previously estimated. Our study suggests an influence of household level improvement in socio-economic status on menarcheal age.L'&eacute;tude actuelle a &eacute;t&eacute; con&ccedil;ue en vue de d&eacute;terminer l'&acirc;ge auquel la menstruation s'&eacute;tablit chez les &eacute;coli&egrave;res &agrave; Medina, Accra. Une enqu&ecirc;te a &eacute;t&eacute; men&eacute;e aupr&egrave;s des 529 filles &agrave; l'aide d'un &eacute;chantillon &agrave; multiples &eacute;tapes tir&eacute;e des &eacute;coles &agrave; Medina, Accra. Les enqu&ecirc;t&eacute;es ont rempli un questionnaire qui a enregistr&eacute; l'&acirc;ge &agrave; la premi&egrave;re menstruation &agrave; travers le rappel, les caract&eacute;ristiques familiales et l'anthropom&eacute;trie. L'&acirc;ge moyen &agrave; la premi&egrave;re menstruation &eacute;tait 12,74&plusmn;1,15 ans ; une analyse par la m&eacute;thode des probits a donn&eacute; un &acirc;ge m&eacute;dian de 12,09 ans. L'&acirc;ge qui se rapporte &agrave; l'&eacute;tablissement de la menstruation &eacute;tait remarquablement corr&eacute;l&eacute; avec l'&acirc;ge actuel (r=0, 48 ; p&lt;0,01). La plupart des filles (90%) avaient leur premi&egrave;re menstruation &agrave; l'&acirc;ge de 13ans. L'&acirc;ge moyen de leurs m&egrave;res au moment de la menstruation &eacute;tait 13,61&plusmn;08 ans Dans un mod&egrave;le de r&eacute;gression lin&eacute;aire multifactoriel, la richesse du m&eacute;nage (p&lt;0,01) et l'indice de masse corporelle (p&lt;0,01) ont &eacute;t&eacute; les principaux indices modifiables de l'&acirc;ge au commencement de la menstruation. Quelques &eacute;coli&egrave;res &agrave; Medina ont commenc&eacute; la menstruation plus t&ocirc;t qu'on avait pr&eacute;vue. Notre &eacute;tude montre qu'il y a une influence de l'am&eacute;lioration du niveau du m&eacute;nage dans l'&eacute;tat socio-&eacute;conomique sur l'&acirc;ge qui se rapporte &agrave; l'&eacute;tablissement de la menstruation.Key words: menarche, Ghana, school, menstruation, teenag

Mortality in a seven-and-a-half-year follow-up of a trial of insecticide-treated mosquito nets in Ghana

A 17% efficacy in preventing all-cause mortality in children aged 6-59 months was previously reported from a cluster-randomized controlled trial of insecticide-treated mosquito nets (ITNs) carried out in the Kassena-Nankana District of northern Ghana from July 1993-June 1995. A follow-up until the end of 2000 found no indication in any age group of increased mortality in the ITN group after the end of the randomized intervention. These results should further encourage the use of ITNs as a malaria control tool in areas of high endemicity of Plasmodium falciparu

Spatio-temporal malaria transmission patterns in Navrongo demographic surveillance site, northern Ghana

The relationship between entomological measures of malaria transmission intensity and mortality remains uncertain. This is partly because transmission is heterogeneous even within small geographical areas. Studying this relationship requires high resolution, spatially structured, longitudinal entomological data. Geostatistical models that have been used to analyse the spatio-temporal heterogeneity have not considered the uncertainty in both sporozoite rate (SR) and mosquito density data. This study analysed data from Kassena-Nankana districts in northern Ghana to obtain small area estimates of malaria transmission rates allowing for this uncertainty.; Independent Bayesian geostatistical models for sporozoite rate and mosquito density were fitted to produce explicit entomological inoculation rate (EIR) estimates for small areas and short time periods, controlling for environmental factors.; Mosquitoes were trapped from 2,803 unique locations for three years using mainly CDC light traps. Anopheles gambiae constituted 52%, the rest were Anopheles funestus. Mean biting rates for An. funestus and An. gambiae were 32 and 33 respectively. Most bites occurred in September, the wettest month. The sporozoite rates were higher in the dry periods of the last two years compared with the wet period. The annual EIR varied from 1,132 to 157 infective bites. Monthly EIR varied between zero and 388 infective bites. Spatial correlation for SR was lower than that of mosquito densities.; This study confirms the presence of spatio-temporal heterogeneity in malaria transmission within a small geographical area. Spatial variance was stronger than temporal especially in the SR. The estimated EIR will be used in mortality analysis for the area

Rates and Causes of Death in Chiradzulu District, Malawi, 2008: A Key Informant Study

In September 2008, we measured all-cause mortality in Chiradzulu District, Malawi (population 291 000) over a 60-day retrospective period, using capture-recapture analysis of three lists of deaths provided by (i) key community informants, (ii) graveyard officials and (iii) health system sources. Estimated crude and under-5-year mortality rates were 18.6 (95% CI 13.9-24.5) and 30.6 (95% CI 17.5-59.9) deaths per 1000 person-years. We also classified causes of death through verbal autopsy interviews on 50 deaths over the previous 40 days. Half of deaths were attributable to infection, and half of deaths among children aged under 5 were attributable to neonatal causes. HIV/AIDS was the leading cause of death (16.6%), with a cause-attributable mortality rate of 1.8 (0.4-3.6) deaths per 1000 person-years

Determinants of Under-Five Mortality in Builsa District, Upper East Region, Ghana

Under-five mortality rate is an important indicator of a community’s social development. The Upper East region, one of the most poverty-stricken regions in Ghana, has however recorded a dramatic decline in its under-five mortality rate since 1993; from 180 per 1000 live births to 79 per 1000 live births in 2003. The aim was to identify the determinants of under-five mortality in Builsa district. A case-control study was used to collect data from mothers of 60 cases and 120 controls matched for age, sex and place of residence. Even though 70% of mothers were illiter-ate, the educational level of mothers did not influence the child’s risk of death (OR 1.1). Chil-dren of mothers who had had previous child deaths were about 8 times more likely to die (OR 7.45,) while those who had not had vitamin A supplementation were about 10 times more likely to die (OR 9.57). Over 90% of mothers had an insecticide-treated bednet and more than 50% of them exclusively breastfed their children for the first 6 months of life. Protective risk factors identified included: exclusive breastfeeding (OR 0.72), use of an insecticide-treated bednet (OR 0.12), the number of live children a mother had (OR 0.54) and immunization (OR 0.53). Even in poverty, it is possible to improve the child health status of communities. Health staff should be equipped to pay special attention to mothers with previous child deaths in order to assist them to prevent further deaths.Keywords: Under-five mortality, determinants, case-control study, Builsa distric

Options for the Delivery of Intermittent Preventive Treatment for Malaria to Children: A Community Randomised Trial

Intermittent preventive treatment for malaria in children (IPTc) is a promising new intervention for the prevention of malaria but its delivery is a challenge. We have evaluated the coverage of IPTc that can be achieved by two different delivery systems in Ghana.IPTc was delivered by volunteers in six villages (community-based arm) and by health workers at health centres or at Expanded Programme on Immunisation outreach clinics (facility based) in another six communities. The villages were selected randomly and drugs were administered in May, June, September and October 2006. The first dose of a three-dose regimen of amodiaquine plus sulphadoxine-pyrimethamine was administered under supervision to 3-59 month-old children (n = 964) in the 12 study villages; doses for days 2 and 3 were given to parents/guardians to administer at home.The proportion of children who received at least the first dose of 3 or more courses of IPTc was slightly higher in the community based arm (90.5% vs 86.6%; p = 0.059). Completion of the three dose regimen was high and similar with both delivery systems (91.6% and 91.7% respectively).Seasonal IPTc delivered through community-based or facility-based systems can achieve a high coverage rate with the support and supervision of the district health management team. However, in order to maximise the impact of IPTc, both delivery systems may be needed in some settings.ClinicalTrials.gov NCT00119132

The effect of medical therapy on IOP control in Ghana

Background: To investigate IOP control following twelve months of continuous medical therapy in Ghana.Methods: This retrospective case series included 163 glaucoma patients diagnosed at a referral eye center between 1996 and 2006. Information collected included age, gender, IOP at presentation, six months and oneyear post treatment and types of anti-glaucoma medications prescribed. Optimal IOP control was defined according to results from the Advanced Glaucoma Intervention Study (AGIS), which demonstrated arrest of visual field progression in patients with IOP &lt; 18 mmHg at all visitations: Level 1 (post-treatment IOP . 21 mmHg); Level 2 (. 18 mmHg) and level 3 (. 16mmHg). The principal outcome measure was the achievement of IOP &lt;18 mmHg at six months and twelve month visitations.Results: One hundred sixty three patients were analyzed. These included 68 males (41.7%) and 95 females (58.3%). The mean age was 57}16  (median 59 years; range 7 . 95 years). There was no significant difference in age (p=0.35) or mean IOP (p=0.08) between genders. The mean pre-treated IOP of 31.9}8.9 mmHg significantly decreased to 21.3}6.6  mmHg at 6 months (p=0.001), with 57.4% of eyes at Level 1 IOP control, 25.3% at Level 2 and 15.4% at Level 3 and decreased further at 12 months to 20.7}6.9 mmHg (p=0.48) with 69.7% of eyes at Level 1, 34.4% at Level 2, and 12.4% at Level 3.Conclusions: Current medical regimen is insufficient to reduce IOP to target levels as defined in the Advanced Glaucoma Intervention Study.Keywords: Glaucoma, POAG, IOP, Ghana, intraocular pressur