Can type 2 diabetes be prevented through diet and exercise?

Diets that result in long-term weight loss of 5% to 7%, along with moderate-intensity exercise for more than 150 minutes per week, reduce the incidence of type 2 diabetes for patients with impaired glucose tolerance (IGT) (strength of recommendation [SOR]: A, based on multiple randomized controlled trials [RCTs]). Each of the trials demonstrating this finding included fairly intensive counseling as part of the successful intervention. Diet and exercise reduce the incidence of diabetes in both lean (body mass index [BMI] <25) and overweight patients with IGT (SOR: B, based on a single, large RCT)

A Land Use Change Monitoring System Based on LANDSAT

A procedure for economically determining statistics on acreages of change in the use of land between two dates has been developed to support a Department of Housing and Urban Development program on neighborhood change modeling. The application of image processing techniques to LANDSAT imagery in four stages (registration, differencing, classification, and tabulation) provides one of the basic data sets needed to model future land use in one of six typical urban areas. After appropriate LANDSAT imagery for two desired dates is obtained, date-to-date registration of the study area is performed. Once the two images are adequately registered, the procedures of determining the geographic areas of change are initiated. The ratio of two raw bands for the early date is computed and then subtracted from the same ratio for the late date. This difference is allowed to conform to a gaussian distribution, and those pixels whose values lie beyond two standard deviations from the mean are designated as areas of change. The first step in the creation of a late date classification map is to extract and classify only those areas that show change. Then the early date classified data for unchanged areas is digitally summed with the late date classified data in changed areas. Using polygon overlay routines individually for both the early and late date classifications and then combining the results, a tabulation revealing general land use changes (e.g., the number of acres of residential in the early date versus the number in the late date) can be generated. To determine the manner of the change (e.g., the number of acres changed from rural to urban), the land use classes are first aggregated into rural/urban dicotomies and then a routine which permits comparison of individual pixel values is executed. Finally, a tabulation can display the manner of the land use change aggregated by the administrative district desired (e.g., census tracts)

Reading Clay: The Temporal and Transformative Potential of Clay in Contemporary Scientific Practice

Clay has a long history in the global south and has been extensively studied by ‘Western’ social scientists particularly anthropologists and archeologists in relation to histories of earlier civilisations and cultural practices. Clay in relation to contemporary ‘science’ has received less attention in social science despite the emergence of the sub-discipline of ‘clay science’ and its increasing focus on clay to transform wide ranging aspects of social life. In this paper we work towards an exploration of clay in science. We begin with the question of ‘what is clay?’ from the perspective of a multidisciplinary group of scientists, whilst being alert to culturally located and past knowledges of clay that shape current scientific knowledges and practices. Drawing on interviews with six clay scientists we explore the ontological and epistemological process for scientists in ‘reading’ clay to reveal how clay is ‘classified’, ‘worked upon’ and ‘partnered’. Our findings suggest that clay comes into being for scientists by being read as an informational and temporal medium and agentic matter with transformative promise to remedy specific threats to human and environmental health

Effects of cryoprotectants on phospholipid monolayers - concentration and species dependence

The effects of four cryoprotectants (dimethylformamide (DMF), ethylene glycol (EG), glycerol and dimethyl sulfoxide (DMSO)) on monolayers of four phospholipids were investigated at high cryoprotectant concentration (10% v/v) relevant to cryoprotection, and compared with previous work at lower concentrations (5% v/v). The results show that the interactions between cryoprotective agents (CPAs) and lipids are complex, with significant differences identified as functions of CPA, concentration and phospholipid species. It was observed that generally DMF and EG cause monolayer compaction, whereas glycerol causes expansion (penetrating the monolayer), although each exhibited subtle differences with different phospholipids. DMSO showed significant differences depending on the headgroup (phosphatidylcholine vs phosphatidylethanolamine) and the physical state of the monolayer. In addition, it was found that DMF was the only CPA capable of penetrating monolayers at physiologically relevant lateral pressures. The results highlight that conclusions based on a single model system (e.g. DPPC) should not be extrapolated to other lipids, and there is a need to study a wider range of lipid species and CPA concentrations in order to understand their mechanisms of action more fullyPeer ReviewedPostprint (author's final draft

The characteristics and performance of concept stocks on the Johannesburg Securities Exchange

The backdrop to this study is derived from an international paper which analysed the characteristics and performance of concept stocks across different North American stock exchanges. The empirical findings indicated that concept stocks underperform the market as well as control stocks. Concept stocks were also found to exhibit abnormally high levels of research and development spending. This study replicates the North American research in the South African setting by analysing the characteristics and performance of concept stocks on the Johannesburg Securities Exchange. The method used analyses a number of the characteristics of the stocks based on financial indices. Their performance is measured using the buy-and-hold abnormal returns method. The results indicated that the concept stocks outperformed their control stocks on certain accounting characteristics, but underperformed on others. The returns generated by the concept stocks significantly underperformed the control stocks, but only in Years 3, 4 and 5. The concept stocks are therefore only accurately valued over the long term.Dissertation (MBA)--University of Pretoria, 2010.Gordon Institute of Business Science (GIBS)unrestricte

Crystallization of dense binary hard-sphere mixtures with marginal size ratio

Molecular dynamics simulations are performed for binary hard-sphere mixtures with a size ratio of γ=0.9 and a volume fraction of ϕ=0.58 over a range of compositions. We show how, at this high volume fraction, crystallization depends sensitively on the composition. Evidence is presented that crystallization in these mixtures does not proceed by the standard nucleation and growth paradigm. Rather, some crystallite forms almost immediately and then an interplay between compositional fluctuations and crystal growth is able to dramatically extend the time scale on which further crystallization occurs. This can be seen as a form of geometric frustration

Dynamical signatures of freezing: stable fluids, metastable fluids, and crystals

Mean squared displacements and velocity auto correlation functions are calculated using molecular dynamics for hard spheres under a range of conditions (i) for the equilibrium fluid below freezing; (ii) for the metastable fluid above freezing; and (iii) for the hard sphere crystal, both in the metastable region between freezing and melting, and in the stable region above melting. In addition, simulations are carried out for a metastable Lennard-Jones system. The results confirm recent studies that indicated the disappearance of the classical Alder long-time tail, and show that they apply to systems other than the metastable hard sphere fluid. The implications of these results for our understanding of crystallization and the glass transition are discussed

Measurement of glucose exclusion from the fully hydrated DOPE inverse hexagonal phase

The degree of exclusion of glucose from the inverse hexagonal HII phase of fully hydrated DOPE is determined using contrast variation small angle neutron scattering and small angle X-ray scattering. The presence of glucose is found to favour the formation of the non-lamellar HII phase over the fluid lamellar phase, over a wide range of temperatures, while having no significant effect on the structure of the HII phase. Glucose is preferentially excluded from the lipid-water interface resulting in a glucose concentration in the HII phase of less than half that in the coexisting aqueous phase. The degree of exclusion is quantified and the results are consistent with a hydration layer of pure water adjacent to the lipid head groups from which glucose is excluded. The osmotic gradient created by the difference in glucose concentration is determined and the influence of glucose on the phase behaviour of non-lamellar phase forming lipid systems is discussed