The diffusion of chloride ion in cement paste.

The effect of the composition of the cement paste with respect to the water:cement ratio and mineral pozzolan content on the effective chloride ion diffusivity is investigated. The diffusivity is found to increase as the water:cement ratio increases. The effectiveness of pyrolized sheet moulding compound in preventing the diffusion of chloride ion is discussed. Pyrolized sheet moulding compound is found to be effective in decreasing the chloride ion diffusivity, and that the diffusivity decreased as the PSMC content of the paste is increased. In addition, the effect of experimental parameters such as sample thickness and concentration gradient, and of modifications to the standard diffusion cell are investigated. A change in the chloride ion concentration in cell 1 of the diffusion cell is found to have no significant effect on the measured chloride ion diffusivity. The sample thickness was found to effect the measured chloride ion diffusivity. (Abstract shortened by UMI.)Dept. of Mechanical, Automotive, and Materials Engineering. Paper copy at Leddy Library: Theses & Major Papers - Basement, West Bldg. / Call Number: Thesis1992 .M226. Source: Masters Abstracts International, Volume: 31-04, page: 1906. Thesis (M.A.Sc.)--University of Windsor (Canada), 1992

Phase-change Nanophotonics

Phase-change materials, including metals, semiconductors and liquid crystals, have played a key role in the evolution of active nanophotonic and plasmonic functionalities. They present unique opportunities at the nano- (i.e. subwavelength) scale as a source of optical nonlinearity and a platform for high-contrast, low-energy electro-and all-optical switching / memory devices. I will review Southampton’s work in this field: from the demonstration of exceptionally large (including metamaterial-enhanced) phase-change nonlinearities underpinned by light-induced, surface-mediated structural transitions in confined gallium; through the harnessing of non-volatile optically-induced amorphous/crystalline transitions in chalcogenides (such as Ge:Sb:Te) to realize plasmonic hybrid and all-dielectric switchable and laser re-writable metasurfaces; to the recent revelation that germanium and bismuth-based chalcogenide alloys can themselves present switchable and compositionally-tunable plasmonic properties in the UV-VIS spectral range

Testing a Hypothesis of Non-REM Sleep Reinforcement and REM Sleep Refinement for the Benefits of Post-Learning Sleep on Memory Retrieval

It is well established that post-learning sleep benefits later memory retrieval, but there is still much to learn about the processes involved and the nature of these benefits. Sleep is composed of stages of non-REM (NREM) and REM sleep: NREM sleep, especially slow wave activity of NREM sleep, and REM sleep have been implicated in memory performance benefits, but the specific contributions of each state remain unclear. This thesis presents a hypothesis proposing that post-learning NREM sleep supports memory accessibility, benefitting the likelihood of successful memory retrieval, and that post-learning REM sleep supports memory fidelity, allowing for more accurate retrieval when retrieval is successful. This hypothesis was tested over studies examining the effects of an afternoon nap (Chapter 2), targeted memory reactivation during NREM slow wave sleep (Chapter 3), and both targeted memory reactivation during NREM slow wave sleep and selective deprivation of REM sleep (Chapter 4) on measures of memory accessibility and memory fidelity in visuospatial memory tasks. In each study, measures of sleep architecture and electroencephalographic power in sleep were examined as predictors of memory performance. Several identified associations and interactions further inform an understanding of how NREM sleep and REM sleep may benefit memory performance. Most notably, these studies consistently found greater slow wave activity of NREM sleep to be specifically associated with better maintenance of memory accessibility. These studies did not identify a clear effect of REM sleep. It is hoped that the hypothesis and findings presented stimulate additional inquires that will further our understanding of the individual and combined contributions of NREM and REM sleep

Association between body condition score and live weight in pasture-based Holstein-Friesian dairy cows

peer-reviewedThe objective was to quantify the strength of the relationship between body condition score (BCS) and live weight (LW) in pasture-based Holstein-Friesian dairy cattle, and to determine the kg LW per unit BCS. A total of 26021 test-day records with information on both BCS (1–10 scale, where 1 is emaciated and 10 is obese) and LW across 1110 lactations from one research farm were used in the analysis. Correlation and regression analyses were used to determine the degree of association between BCS and LW in different parities, stages of the inter-calving interval and years. Correlations between BCS and LW were relatively consistent, with the mean correlation between BCS and LW across all data of 0·55 implying that differences in BCS explain approximately 30% of the variation in LW. Significantly different regressions of LW on BCS were present within stage of inter-calving interval by parity subclasses. Excluding calving, LW per unit BCS varied from 17 kg (early to mid lactation in parity 1) to 36 kg (early lactation in parity 4 and 5). However, LW per unit BCS was greatest at calving varying from 44 kg in first parity animals to 62 kg in second parity animals. On average, 1 BCS unit equated to 31 kg LW across all data

The determinants of wealth and gender inequity in cognitive skills in Latin America

Wealth and gender inequity in the accumulation of cognitive skills is measured as the association between subject competency and wealth and gender using the OECD’s Programme for International Student Assessment. Wealth inequity is found to occur not through disparate household characteristics but rather through disparate school characteristics; little evidence is found of an association between wealth and competency within schools. Weak evidence is found of wealth mitigating gender differences through school characteristics. These findings suggest that wealth inequity in the accumulation of cognitive skills is almost exclusively associated with disparate school characteristics and that disparate school characteristics may play a role in accentuating gender inequity.Tertiary Education,Education For All,Disability,Primary Education,Secondary Education

Pre-existing condition : taking media coverage into account when preparing for H1N1

This paper examines the claim that media exaggerated the threat of H1N1, prompting an immediate demand for limited vaccine. We compare the Australian’s and the Daily Telegraph’s (UK) coverage of H1N1 with the coverage in the Globe and Mail, which is comparatively critical of government performance. The events of October 2009 underscore the difficulty and importance of responding to media coverage of “uncertain risks” (Renn 2008), risks for which there is a lack of scientific basis for decision making and which potentially generate anxious public responses

Antiepileptic Drug Mechanisms of Action

Clinically used antiepileptic drugs (AEDs) decrease membrane excitability by interacting with ion channels or neurotransmitter receptors. Currently available AEDs appear to act on sodium channels, GABA A receptors, or calcium channels. Phenytoin, carbamazepine, and possibly valproate (VPA) decrease high-frequency repetitive firing of action potentials by enhancing sodium channel inactivation. Benzodiazepines and barbiturates enhance GABA A receptor-mediated inhibition. Ethosuximide and possibly VPA reduce a low-threshold calcium current. The mechanisms of action of AEDs currently under development are less clear. Lamotrigine may decrease sustained high-frequency repetitive firing. The mechanisms of action of felbamate are unknown. Gabapentin (GBP) appears to bind to a specific binding site in the central nervous system with a restricted regional distribution, but the identity of the binding site and the mechanism of action of GBP remain uncertain.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/66291/1/j.1528-1157.1993.tb05918.x.pd