Use of distance education for teacher training and development in Malawi: models, practices, and successes

This article argues that the distance education (DE) delivery model has the potential to offer education and training to a greater majority of Malawians who, for one reason or another, cannot be accommodated in the traditional face-to-face delivery model. Motivated by the need to understand the delivery models employed by DE institutions in the country, the technologies they employ, and the need to gauge major successes of this model of provision, an audit study involving Mzuzu University, the Domasi College of Education, the Malawi College of Distance Education, the Department of Teacher Education and Development, Chancellor College, the Malawi Polytechnic, and Aggrey Memorial School was conducted in 2012. This was necessitated by the need to establish the nature and effi cacy of distance education in Malawi. The major fi nding of the study is that, although this model of delivery has allowed access to education and training for people who otherwise would have been denied the opportunity because of the restrictive nature of the face-to-face delivery mode, DE institutions in Malawi continue to face challenges pertaining to the use of basic, rudimentary and often obsolete technologies, which make the delivery model cumbersome for both tutors and learners. The implication is that the full potential of this delivery model has been attenuated by the use of such instructional technologies. The paper recommends that Malawi must invest in the requisite infrastructure and appropriate technologies to enhance the effi cacy of distance education and e-learning as a means of broadening and increasing access to education and training.Proceedings of the 5th biennial International Conference on Distance Education and Teachers’ Training in Africa (DETA) held at the University of Nairobi, Nairobi, Kenya, 30 July - 1 August 2013

Anne Gennings

Anne Gennings of New York State, started her career as a hospital dietitian and served as president of New York State Dietetics. Gennings then became the food service director at New Harvard Central School and stayed in that position for thirty-three years. She was president of the New York School Nutrition Association in the late 1980s and president of the American School Food Service Association in the early 1990s.https://egrove.olemiss.edu/icn_ohistories/1057/thumbnail.jp

Evaluating Geographically Weighted Regression Models for Environmental Chemical Risk Analysis

In the evaluation of cancer risk related to environmental chemical exposures, the effect of many correlated chemicals on disease is often of interest. The relationship between correlated environmental chemicals and health effects is not always constant across a study area, as exposure levels may change spatially due to various environmental factors. Geographically weighted regression (GWR) has been proposed to model spatially varying effects. However, concerns about collinearity effects, including regression coefficient sign reversal (ie, reversal paradox), may limit the applicability of GWR for environmental chemical risk analysis. A penalized version of GWR, the geographically weighted lasso, has been proposed to remediate the collinearity effects in GWR models. Our focus in this study was on assessing through a simulation study the ability of GWR and GWL to correctly identify spatially varying chemical effects for a mixture of correlated chemicals within a study area. Our results showed that GWR suffered from the reversal paradox, while GWL overpenalized the effects for the chemical most strongly related to the outcome

Assessment of Weighted Quantile Sum Regression for Modeling Chemical Mixtures and Cancer Risk

In evaluation of cancer risk related to environmental chemical exposures, the effect of many chemicals on disease is ultimately of interest. However, because of potentially strong correlations among chemicals that occur together, traditional regression methods suffer from collinearity effects, including regression coefficient sign reversal and variance inflation. In addition, penalized regression methods designed to remediate collinearity may have limitations in selecting the truly bad actors among many correlated components. The recently proposed method of weighted quantile sum (WQS) regression attempts to overcome these problems by estimating a body burden index, which identifies important chemicals in a mixture of correlated environmental chemicals. Our focus was on assessing through simulation studies the accuracy of WQS regression in detecting subsets of chemicals associated with health outcomes (binary and continuous) in site-specific analyses and in non-site-specific analyses. We also evaluated the performance of the penalized regres-sion methods of lasso, adaptive lasso, and elastic net in correctly classifying chemicals as bad actors or unrelated to the outcome. We based the simulation study on data from the National Cancer Institute Surveillance Epidemiology and End Results Program (NCI-SEER) case–control study of non-Hodgkin lymphoma (NHL) to achieve realistic exposure situations. Our results showed that WQS regression had good sensitivity and specificity across a variety of conditions considered in this study. The shrinkage methods had a tendency to incorrectly identify a large number of components, especially in the case of strong association with the outcome

Investigation of Chemically Prestressed Concrete

This research investigated the possibility of prestressing a concrete element by inducing expansion of the concrete paste at an early age. This behavior is being called chemically prestressed concrete, for this project, was studied by varying the amount of expansion. A literature review was performed which outlines different experiments investigating the chemical prestressing of concrete. Two of the main focuses of the literature review are the chemical structure of calcium sulfo-aluminate cements and chemically induced axial force. Phase one of this research was to investigate the varying levels of expansion by using 21%, 23%, 25%, 27%, and 29% replacement by weight of portland cement with an expansive mineral admixture. The mix designs developed in phase one of this research utilized the varying percentages of expansive mineral admixture. The concrete’s expansion or shrinkage was measured over an extended period using restrained prisms and restrained cylinders. The specimens were wet cured for the first seven days, allowing expansion to develop. The prisms were measured using a length comparator. The restrained cylinders were measured using a vibrating wire strain gage (VWSG) system. The VWSG were connected to a Geokon data acquisition system to constantly read the expansion or shrinkage at an interval of 15 minutes. Phase two of this research investigated the use of internal restraint to develop the prestress of the concrete. The internal restraint conditions included four types of steel fibers: CTS proprietary, Novocon 1050 he, Novocon XR, and Dramix. The mix design with 25% replacement of Portland cement with the expansive mineral admixture was used throughout phase two. The same type of restrained prisms and restrained cylinders were monitored to determine the amount of restraint provided by each fiber type. Phase three of this researched included casting a series of slabs to examine the behavior on a larger scale. Three slabs were cast using the 25% replacement of Portland cement with the expansive mineral admixture to monitor the amount of restraint provided by the differing reinforcements. Slab 1 had no reinforcement of steel fibers in the 25% replacement of Portland cement with the expansive mineral admixture, slab 2 had a No. 5 bar around the edges of the slab, and slab 3 had the Novocon XR steel fibers. All three slabs were instrumented with three VWSG’s throughout. The VWSG’s were placed longitudinally along the tip and midpoint and transversely in the midpoint of the slab. The tests conducted show how significantly a change in the percentage of expansive mineral admixture can affect the expansion of the concrete. The results show a trend in which increasing expansive mineral admixture created increased expansion. The steel fibers created internal restraint of the expansion, but each fiber type created a different level of restraint. The fibers internal restraint can create a material induced prestress by restricting the expansion and carrying the associated stress from restraining the expansion. Chemically prestressed slabs have the potential for becoming used in industry, but the sizing effect must be accounted for when designing

Human Microbiome Mixture Analysis Using Weighted Quantile Sum Regression

: Studies of the health effects of the microbiome often measure overall associations by using diversity metrics, and individual taxa associations in separate analyses, but do not consider the correlated relationships between taxa in the microbiome. In this study, we applied random subset weighted quantile sum regression with repeated holdouts (WQSRSRH), a mixture method successfully applied to 'omic data to account for relationships between many predictors, to processed amplicon sequencing data from the Human Microbiome Project. We simulated a binary variable associated with 20 operational taxonomic units (OTUs). WQSRSRH was used to test for the association between the microbiome and the simulated variable, adjusted for sex, and sensitivity and specificity were calculated. The WQSRSRH method was also compared to other standard methods for microbiome analysis. The method was further illustrated using real data from the Growth and Obesity Cohort in Chile to assess the association between the gut microbiome and body mass index. In the analysis with simulated data, WQSRSRH predicted the correct directionality of association between the microbiome and the simulated variable, with an average sensitivity and specificity of 75% and 70%, respectively, in identifying the 20 associated OTUs. WQSRSRH performed better than all other comparison methods. In the illustration analysis of the gut microbiome and obesity, the WQSRSRH analysis identified an inverse association between body mass index and the gut microbe mixture, identifying Bacteroides, Clostridium, Prevotella, and Ruminococcus as important genera in the negative association. The application of WQSRSRH to the microbiome allows for analysis of the mixture effect of all the taxa in the microbiome, while simultaneously identifying the most important to the mixture, and allowing for covariate adjustment. It outperformed other methods when using simulated data, and in analysis with real data found results consistent with other study findings

Randomized trial comparing daily interruption of sedation and nursing-implemented sedation algorithm in medical intensive care unit patients

Introduction Daily interruption of sedation (DIS) and sedation algorithms (SAs) have been shown to decrease mechanical ventilation (MV) duration. We conducted a randomized study comparing these strategies. Methods Mechanically ventilated adults 18 years old or older in the medical intensive care unit (ICU) were randomly assigned to DIS or SA. Exclusion criteria were severe neurocognitive dysfunction, administration of neuromuscular blockers, and tracheostomy. Study endpoints were total MV duration and 28-day ventilator-free survival. Results The study was terminated prematurely after 74 patients were enrolled (DIS 36 and SA 38). The two groups had similar age, gender, racial distribution, Acute Physiology and Chronic Health Evaluation II score, and reason for MV. The Data Safety Monitoring Board convened after DIS patients were found to have higher hospital mortality; however, no causal connection between DIS and increased mortality was identified. Interim analysis demonstrated a significant difference in primary endpoint, and study termination was recommended. The DIS group had longer total duration of MV (median 6.7 versus 3.9 days; P = 0.0003), slower improvement of Sequential Organ Failure Assessment over time (0.70 versus 0.23 units per day; P = 0.025), longer ICU length of stay (15 versus 8 days; P \u3c 0.0001), and longer hospital length of stay (23 versus 12 days; P = 0.01). Conclusion In our cohort of patients, the use of SA was associated with reduced duration of MV and lengths of stay compared with DIS. Based on these results, DIS may not be appropriate in all mechanically ventilated patients

A Cohort study evaluation of maternal PCB exposure related to time to pregnancy in daughters

Background: Polychlorinated biphenyls (PCBs) remain ubiquitous environmental contaminants. Developmental exposures are suspected to impact reproduction. Analysis of mixtures of PCBs may be problematic as components have a complex correlation structure, and along with limited sample sizes, standard regression strategies are problematic. We compared the results of a novel, empirical method to those based on categorization of PCB compounds by (1) hypothesized biological activity previously proposed and widely applied, and (2) degree of ortho- substitution (mono, di, tri), in a study of the relation of maternal serum PCBs and daughter’s time to pregnancy. Methods: We measured PCBs in maternal serum samples collected in the early postpartum in 289 daughters in the Child Health and Development Studies birth cohort. We queried time to pregnancy in these daughters 28–31 years later. We applied a novel weighted quantile sum approach to find the bad-actor compounds in the PCB mixture found in maternal serum. The approach includes empirical estimation of the weights through a bootstrap step which accounts for the variation in the estimated weights. Results: Bootstrap analyses indicated the dominant functionality groups associated with longer TTP were the dioxin-like, anti-estrogenic group (average weight, 22%) and PCBs not previously classified by biological activity (54%). In contrast, the unclassified PCBs were not important in the association with shorter TTP, where the anti-estrogenic groups and the PB-inducers group played a more important role (60% and 23%, respectively). The highly chlorinated PCBs (average weight, 89%) were mostly associated with longer TTP; in contrast, the degree of chlorination was less discriminating for shorter TTP. Finally, PCB 56 was associated with the strongest relationship with TTP with a weight of 47%. Conclusions: Our empirical approach found some associations previously identified by two classification schemes, but also identified other bad actors. This empirical method can generate hypotheses about mixture effects and mechanisms and overcomes some of the limitations of standard regression techniques