Nitrogen Status of Soils of Selected Land-uses of Two Cropping Systems in the Humid Tropical Rainforest, Southeastern Nigeria

Nitrogen status of soils provides information about the capacity of soils to sustain crop productivity and maintain environmental safety. Nitrogen status of soils of selected land-use types of perennial and annual cropping systems were evaluated in the humid tropical rainforest zone, southeastern, Nigeria. Experimental design was a 6 x 3 factorial replicated 3 times in a randomized complete block setup. Total N, NH4-N, NO3-N and organic N were determined. Also correlation between selected soil properties and various N forms were estimated. Nitrogen forms significantly (LSD 0.05) decreased in the order Oil palm > cocoyam > cashew > rubber > cassava > yam, oil palm > cocoyam > rubber > cashew > yam > cassava, oil palm > cashew > rubber = cocoyam > yam > cassava and oil palm > cashew > rubber > cocoyam > yam > cassava for NH4-N, NO3-N, organic N and total N respectively and with each higher in the surface 0-15 cm than the other soil depths. Mean soil concentrations of land uses under perennial and annual cropping systems were 3.69 and 2.23 mg kg-1 NH4-N, 8.56 and 5.50 mg kg-1 NO3-N, 0.20 and 0.17 g kg-1 organic N and 0.22 and 0.19 g kg-1total N respectively, with the former better than the later. Nitrogen status of the various land use types correlated with soil clay, silt, OM, available P, ECEC and pH. In general, N status varied with land uses under perennial and annual cropping systems and low indicating the need for external N input for crop sustenance and inability for environmental pollution. Keywords: Nitrogen, Land use, Cropping Systems, Humid Tropics and Southeastern Nigeri

Model exploration and analysis for quantitative safety refinement in probabilistic B

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.Comment: In Proceedings Refine 2011, arXiv:1106.348

Sexual Behavior and Abuse: A Case Study of University Undergraduates in Tertiary Institutions in Imo State, Nigeria

Introduction: In young people including adolescents, risky sexual behavior has been recognized as an important health, social and demographic concern in the developing world. Aim: To assess sexual behaviors and their association with current and life-time occurrence of sexual abuse among female undergraduates in tertiary institutions in Imo State, Nigeria. Methodology: This was a school based cross sectional study involving 600 female students selected from tertiary institutions in Imo State Nigeria, using the multistage sampling technique. Data was collected using a semi-structured, self-administered questionnaire and analyzed using a data software (EPI-INFO version 3.3.2). Descriptive variables were presented using summary indices, frequency tables/percentages, and graph while associations between variables were done using the Chi-square and binary regression. A p-value of 0.05 was considered significant. Results: The mean age of the students was 21.73.2 years. About 65.2% of the respondents have initiated sexual intercourse and of this proportion, 75.6% were sexually active in the last one year preceding survey. The mean age at initiation of sexual debut among the students was 18.93.8 years and the commonest form of sexual act practiced was penile/vaginal sex. About 15.2% of the students had been currently abused. Predictors of current sexual abuse were; ever had sexual intercourse (OR.4.63), being within 14-19 years of age at first sexual initiation, (OR: 0.42), had first sexual exposure with a casual partner (OR: 12.38), and being sexually active in the last 1 year preceding study, (OR: 2.16). Conclusion: Risky sexual behaviors were prevalent and were found to influence the occurrence of sexual abuse, among the students. Thus, there is need to institute appropriate prevention strategies to limit risky sexual behaviors and it consequences among adolescents and young adults

A UTP semantics of pGCL as a homogeneous relation

We present an encoding of the semantics of the probabilis- tic guarded command language (pGCL) in the Unifying Theories of Programming (UTP) framework. Our contribution is a UTP encoding that captures pGCL programs as predicate-transformers, on predicates over probability distributions on before- and after-states: these predi- cates capture the same information as the models traditionally used to give semantics to pGCL; in addition our formulation allows us to de- ne a generic choice construct, that covers conditional, probabilistic and non-deterministic choice. As an example we study the Monty Hall game in this framework

Longitudinal Ambient PM<inf>2.5</inf> Measurement at Fifteen Locations in Eight Sub-Saharan African Countries Using Low-Cost Sensors

Peer reviewed: TrueFunder: Medical Research Council Doctoral Training Program scholarshipFunder: Aldama FoundationFunder: NIHR Global Health Research Unit on Lung Health and TB in Africa at LSTM— “IMPALA”Funder: National Institute for Health Research (NIHR) using UK aid from the UK Government to support global health researchAir pollution is a major global public health issue causing considerable morbidity and mortality. Measuring levels of air pollutants and facilitating access to the data has been identified as a pathway to raise awareness and initiate dialogue between relevant stakeholders. Low-and middle-income countries (LMICs) urgently need simple, low-cost approaches to generate such data, especially in settings with no or unreliable data. We established a network of easy-to-use low-cost air quality sensors (PurpleAir-II-SD) to monitor fine particulate matter (PM2.5) concentrations at 15 sites, in 11 cities across eight sub-Saharan Africa (sSA) countries between February 2020 and January 2021. Annual PM2.5 concentrations, seasonal and temporal variability were determined. Time trends were modelled using harmonic regression. Annual PM2.5 concentrations ranged between 10 and 116 µg/m3 across study sites, exceeding the current WHO annual mean guideline level of 5 µg/m3. The largest degree of seasonal variation was seen in Nigeria, where seven sites showed higher PM2.5 levels during the dry than during the wet season. Other countries with less pronounced dry/wet season variations were Benin (20 µg/m3 versus 5 µg/m3), Uganda (50 µg/m3 versus 45 µg/m3), Sukuta (Gambia) (20 µg/m3 versus 15 µg/m3) and Kenya (30 µg/m3 versus 25 µg/m3). Diurnal variation was observed across all sites, with two daily PM2.5 peaks at about 06:00 and 18:00 local time. We identified high levels of air pollution in the 11 African cities included in this study. This calls for effective control measures to protect the health of African urban populations. The PM2.5 peaks around ‘rush hour’ suggest traffic-related emissions should be a particular area for attention.</jats:p