Relationship between voids and interlaminar shear strength of polymer matrix composites

The effect of voids on the interlaminar shear strength of a polyimide matrix composite system is described. The AS4 graphite/PMR-15 composite was chosen for study because this system can be readily processed by using the standard specified cure cycle to produce void-free composites and because preliminary work in this study had shown that the processing parameters of this resin matrix system can be altered to produce cured composites of varying void contents. Thirty-eight 12-ply unidirectional composite panels were fabricated for this study. A significant range of void contents (0 to 10 percent) was produced. The panels were mapped, ultrasonically inspected, and sectioned into interlaminar shear, flexure, and fiber content specimens. The density of each specimen was measured and interlaminar shear and flexure strength measurements were then made. The fiber content was measured last. The results of these tests were evaluated by using ultrasonic results, photomicrographs, statistical methods, theoretical relationships derived by other investigators, and comparison of the test data with the Integrated Composite Analyzer (ICAN) computer program developed at the Lewis Research Center for predicting composite ply properties. The testing is described in as much detail as possible in order to help others make realistic comparisons

ICAN sensitivity analysis

A computer program called Integrated Composite Analyzer (ICAN) was used to predict the properties of high-temperature polymer matrix composites. ICAN is a collection of NASA Lewis Research Center-developed computer codes designed to carry out analysis of multilayered fiber composites. The material properties used as input to the program were those of the thermoset polyimide resin PMR-15 and the carbon fiber Celion 6000. The sensitivity of the predicted composite properties to variations in the resin and fiber properties was examined. In addition, the predicted results were compared with experimental data. In most cases, the effect of changes in resin and fiber properties on composite properties was reasonable. However, the variations in the composite strengths with the moisture content of the PMR-15 resin were inconsistent. The ICAN-predicted composite moduli agreed fairly well with experimental values, but the predicted composite strengths were generally lower than experimental values

Urbanization and Pattern of Urban Food Consumption in Ashanti Region, Ghana: Implications for Food Security

The study assesses the influence of rapid urbanization on urban consumption pattern and food security of the urban dweller using primary data collected from urban households in Ashanti region of Ghana. The food security index was estimated based on a minimum daily calorie requirement of 2900Kcal. The consumption pattern indicates that yam, cassava and rice are gaining importance in urban household diet in the region. The expenditure share also shows that food constitutes 74.6% of urban household budget. The estimated food security index of the region is 0.66, implying that on average urban households in the region are food insecure. The results further show that 78.5% of the respondents are food insecure whiles  34.2%  are affected by severe food insecurity. The study therefore recommends that government and other stakeholders should promote the consumption of local foods by branding local foods. Also, creation of alternative livelihood activities in urban areas could increase household income and increase their access to food. Keywords: Urbanization, Consumption pattern, Food security, Urban Household

College Climate and Teacher-Trainee’s Academic Work in Selected Colleges of Education in the Ashanti Region of Ghana

The study aimed at investigating the extent to which College climate (Leadership roles/practices and Class size) impact on academic work of Teacher-trainees. A survey research design was used for the study because it involved a study of relatively large population who were purposively and randomly selected. A sample size of 322 out of the population of 1850 from Offinso, Akokerri and Wesley Colleges of Education comprising 226 males and 114 females were used for the study. A questionnaire and an interview guide were used to collect data for the study. The data collected were analyzed using Means, Standard deviations and Analysis of Variance (ANOVA). The study established that effective leadership roles and practices of Principals and Tutors had impact on the academic work of Teacher-trainees. By implication, good leadership practices had a positive relationship with students’ academic work. The results of the ANOVA tests indicated that there was no significant difference in the means of the responses on College class size provided by the respondents (p>-.05). The implication is that large class sizes turn to affect classroom teaching and learning as compared to small class size. The respondents from Offinso College had the lowest mean of 2.41on infrastructure, implying that their College infrastructure was the least developed. However, the respondents of Akokerri had an overall mean of 3.55 which implied that their College infrastructure was moderately developed. The study also revealed that, the higher the academic qualification of college tutors in their respective area of study, the more likely they are to impact positively on the academic work of Teacher-trainees. Keywords:Leadership, School/College Climate, Organic Leadership and Transformational Leadership

Teachers’ Concerns Towards the Implementation of ICT Curriculum in Basic Schools in Kumasi Metropolis

The study sought to assess concerns of teachers regarding the implementation of ICT curriculum in basic schools in Kumasi metropolis. It also examined the relationship between gender and teachers’ stages of concerns. A multi-stage sampling procedure was adopted in selecting the sample for the study. The Stages of Concern Questionnaire was modified and used to gather data from 181 male and 165 female ICT teachers. Both descriptive and inferential statistics were used in analysing the data. Results showed that teachers generally had high consequence and informational concerns and low concern at awareness stage. This indicates that teachers were more bothered on the impact of the ICT curriculum on their students and also lacked requisite knowledge and skills in implementing the curriculum. Moreover, the independent sample t-test conducted revealed statistically significant relationship between gender and informational, management, consequence, collaboration and refocusing concerns. It was recommended among others that GES should embark on rigorous educational programmes in order to upgrade teachers’ knowledge and skills on the ICT curriculum. Keywords: Basic school teachers, Gender, ICT curriculum, Teachers’ Concern

Policy-reality gaps in Africa’s walking cities: Contextualizing institutional perspectives and residents’ lived experiences in Accra

This paper confronts the current policy landscape and lived experiences of walking in African cities through the lens of policies, plans, institutional, and residents’ narratives. The paper builds on qualitative evidence drawn from content analysis and semi-structured interviews with local-level stakeholders across policy sectors concerned directly or indirectly with walking and walkability in the city. Perspectives from local government institutions are first reviewed to ascertain considerations for accessibility, safety, and pleasurability dimensions of walking and, second, contrasted with the lived walking experiences of residents of low-income settlements in Accra. Results indicate limited attention to pleasurability dimensions in both policy and municipal plans and significant incongruities with residents’ lived realities of walking. This parallel between the frameworks and plans underpinning the construction of the walking environment and the lived experiences of those affected by such decisions seeks to nuance debates about policy-reality (dis)junctures in African urbanism

Examples of Risk Tools for Pests in Peanut (Arachis hypogaea) Developed for Five Countries Using Microsoft Excel

Suppressing pest populations below economically-damaging levels is an important element of sustainable peanut (Arachis hypogaea L.) production. Peanut farmers and their advisors often approach pest management with similar goals regardless of where they are located. Anticipating pest outbreaks using field history and monitoring pest populations are fundamental to protecting yield and financial investment. Microsoft Excel was used to develop individual risk indices for pests, a composite assessment of risk, and costs of risk mitigation practices for peanut in Argentina, Ghana, India, Malawi, and North Carolina (NC) in the United States (US). Depending on pests and resources available to manage pests, risk tools vary considerably, especially in the context of other crops that are grown in sequence with peanut, cultivars, and chemical inputs. In Argentina, India, and the US where more tools (e.g., mechanization and pesticides) are available, risk indices for a wide array of economically important pests were developed with the assumption that reducing risk to those pests likely will impact peanut yield in a positive manner. In Ghana and Malawi where fewer management tools are available, risks to yield and aflatoxin contamination are presented without risk indices for individual pests. The Microsoft Excel platform can be updated as new and additional information on effectiveness of management practices becomes apparent. Tools can be developed using this platform that are appropriate for their geography, environment, cropping systems, and pest complexes and management inputs that are available. In this article we present examples for the risk tool for each country.Instituto de Patología VegetalFil: Jordan, David L. North Carolina State University. Department of Crop and Soil Sciences; Estados UnidosFil: Buol, Greg S. North Carolina State University. Department of Crop and Soil Sciences; Estados UnidosFil: Brandenburg, Rick L. North Carolina State University. Department of Entomology and Plant Pathology; Estados UnidosFil: Reisig, Dominic. North Carolina State University. Department of Entomology and Plant Pathology; Estados UnidosFil: Nboyine, Jerry. Council for Scientific and Industrial Research. Savanna Agricultural Research Institute; GhanaFil: Abudulai, Mumuni. Council for Scientific and Industrial Research. Savanna Agricultural Research Institute; GhanaFil: Oteng-Frimpong, Richard.Council for Scientific and Industrial Research. Savanna Agricultural Research Institute; GhanaFil: Brandford Mochiah, Moses.Council for Scientific and Industrial Research. Crops Research Institute; GhanaFil: Asibuo, James Y. Council for Scientific and Industrial Research. Crops Research Institute; GhanaFil: Arthur, Stephen. Council for Scientific and Industrial Research. Crops Research Institute; GhanaFil: Paredes, Juan Andrés. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Fitopatología y Modelización Agrícola (UFyMA); ArgentinaFil: Paredes, Juan Andrés. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Monguillot, Joaquín Humberto. Consejo Nacional de Investigaciones Científicas y Técnicas. Unidad de Fitopatología y Modelización Agrícola (UFyMA); ArgentinaFil: Monguillot, Joaquín Humberto. Instituto Nacional de Tecnología Agropecuaria (INTA). Instituto de Patología Vegetal; ArgentinaFil: Rhoads, James. University of Georgia. Feed the Future Innovation Lab for Peanut; Estados Unido

Effects of Two Environmental Best Management Practices on Pond Water and Effluent Quality and Growth of Nile Tilapia, Oreochromis niloticus

The trajectory of aquaculture growth in sub-Saharan Africa has necessitated closer attention to the use of environmental best management practices (BMPs). Two BMPs in particular, water reuse and floating feeds, are being promoted for adoption by pond fish farmers in sub-Saharan Africa. In this study, we investigated: (1) the effect of water source and feed type on water quality; (2) the effect of water source and feed type on tilapia growth; and (3) the quality of potential effluents from ponds using different water source and feed types. The study was conducted in Ghana using on-farm experiments involving monitoring of water quality and growth of Nile tilapia Oreochromis niloticus for 160 days. Although considered low-intensity production systems, nutrients and solids in the study ponds exceeded levels expected in intensive culture ponds by wide margins, whereas BOD₅ was within the range for semi-intensive ponds. Floating feed was associated with higher water quality, especially dissolved oxygen, and higher growth, but water source did not significantly affect growth. Water reuse appears to be a viable BMP for sustainable aquaculture in the region, but the use of floating feed as BMP will depend on the economic profitability of floating feed use.This is the publisher’s final pdf. The published article is copyrighted by the author(s) and published by MDPI. The published article can be found at: http://www.mdpi.com/journal/sustainability.Keywords: Water quality, Fish production, Floating feeds, Environmental assessment, Sub-Saharan Africa, Water reuse, Aquaculture, Ghana, Tilapia, Effluent, BMPsKeywords: Water quality, Fish production, Floating feeds, Environmental assessment, Sub-Saharan Africa, Water reuse, Aquaculture, Ghana, Tilapia, Effluent, BMP

Unrecognized hypertension among a general adult Ghanaian population: An urban community-based cross-sectional study of prevalence and putative risk factors of lifestyle and obesity indices

Hypertension (HTN) is the leading cause of cardiovascular diseases. Nevertheless, most individuals in developing countries are unaware of their blood pressure status. We determined the prevalence of unrecognized hypertension and its association with lifestyle factors and new obesity indices among the adult population. This community-based study was conducted among 1288 apparently healthy adults aged 18–80 years in the Ablekuma North Municipality, Ghana. Sociodemographic, lifestyle characteristics, blood pressure and anthropometric indices were obtained. The prevalence of unrecognized HTN was 18.4% (237 / 1288). The age groups 45–54 years [aOR = 2.29, 95% CI (1.33–3.95), p = 0.003] and 55–79 years [aOR = 3.25, 95% CI (1.61–6.54), p = 0.001], being divorced [aOR = 3.02 95% CI (1.33–6.90), p = 0.008], weekly [aOR = 4.10, 95% CI (1.77–9.51), p = 0.001] and daily alcohol intake [aOR = 5.62, 95% CI (1.26–12.236), p = 0.028] and no exercise or at most once a week [aOR = 2.25, 95% CI (1.56–3.66), p = 0.001] were independently associated with HTN. Among males, the fourth quartile (Q4) of both body roundness index (BRI) and waist to height ratio (WHtR) [aOR = 5.19, 95% CI (1.05–25.50), p = 0.043] were independent determinants of unrecognized HTN. Among females, the third quartile (Q3) [aOR = 7.96, 95% CI (1.51–42.52), p = 0.015] and Q4 [aOR = 9.87 95% CI (1.92–53.31), p = 0.007] of abdominal volume index (AVI), the Q3 of both BRI and WHtR [aOR = 6.07, 95% CI (1.05–34.94), p = 0.044] and Q4 of both BRI and WHtR [aOR = 9.76, 95% CI (1.74–54.96), p = 0.010] were independent risk factors of HTN. Overall, BRI (AUC = 0.724) and WHtR (AUC = 0.724) for males and AVI (AUC = 0.728), WHtR (AUC = 0.703) and BRI (AUC = 0.703) for females yielded a better discriminatory power for predicting unrecognized HTN. Unrecognized hypertension is common among the apparently healthy adults. Increased awareness of its risk factors, screening, and promoting lifestyle modification is needed to prevent the onset of hypertension