INTRODUCTION According to ILO (2000), in developing countries about 59 per cent of labour force belongs to the agriculture sector. This is a particularly serious concern from the viewpoint of promoting the health of a population and reduction of social vulnerability in a country like Mozambique where more than half of the population depends on agriculture as their means of survival and wage earning. The current study attempts to address the agriculture mineral dust as occupational hygiene and health risk factors among agriculture workers, taking into account that dust that is breathed in may contain quartz, known as a carcinogenic and pathogenic agent. OBJECTIVE OF THE STUDY The study aims to pinpoint risk potential to health that may be caused by mineral dust through assessing occupational exposure doses to respirable dust and quartz during plowing, and primary and secondary tilling operations identified in the study, as the major dust risk operations; and the more prevailing operations in maize and root plant on medium sized farms‟ production cycle. MATERIALS AND METHODS Sampling of dust was conducted on 2 medium sized farms selected by convenience in the district of Boane (study setting) based on geological map soil characterisation of the study area. Full-time period dust samples were collected from 4 different tractor operators. The tractor operators were identified as the risky group. In total were taken seventy valid samples; thirty-nine from maize and thirty-one from root plant. Three tractor operators were fully engaged in maize cultivation and 1 was engaged in root plant during the period of the study data collection. In all occasions, the „open-cabbed‟ tractor machines were observed and used by tractor operators. The involved sampling subjects‟ operators were informed in advance about the study purpose and they accepted participation in the research. Nineteen dust samples were randomly selected for determination of the quartz fraction using the MDHS 101 Infrared Spectrophotometer Method. Active dust sampling MDHS 14/3 HD-cyclone method was applied with GLA 5000 filter type. All quality control procedures applied in active dust sampling method and gravimetric determination of concentration were checked in order to accept or reject samples for further analysis and determination of exposure concentration. RESULTS Standard statistical procedures and sampling strategy data analysis and interpretation procedures, including the SPSS software version 11.5 were used to produce valid results and findings. In the specific case of the agriculture sector, workers are found in changeable conditions and working time, therefore the effective working time distribution was estimated varying at a level of 311.6 min., 95 per cent CI (294-329.7). The observed minimal and maximal values were 179 and 500 min., respectively. The filter medium potential contamination was checked out through determination of the mass variation of the blank samples. The filter contamination was assumed possible through absorption and/or adsorption of humidity at level of minus 0.00407 mg with lower limit of minus 0.01 and upper limit of 0.00183 mg. The results on exposure indicate high exposure dose in maize crop cultivation in contrast to root plant crop cultivation. The findings show that in medium-sized farming, the average exposure to respirable dust is 0.702 (SD 0.571) and the average exposure for respirable quartz is 0.074 (SD 0.06). About 96 per cent of respirable dust exposure measurements were found in compliance with the South Africa standard for respirable dust; and for respirable quartz 74 per cent, 45 per cent and 17 per cent of exposure measurements were in compliance with the SA, NIOSH and ACGIH occupational exposure limits respectively. Each tractor operator‟s measurements showed a significant variation of the exposure concentration, probably due to the intraday and interday variation. The exposure measurements geometric standard deviation (GSD) was found equal or above 2.0 for both maize and root plant measurements and this indicates the influence of environmental factors in the exposure profile variation. CONCLUSION The research is supportive of some international published studies in which respirable quartz exposure in agriculture sector, although highly variable, has potential significance for over-exposure. The measurements of exposure to respirable quartz have shown over-exposure scenarios. However some were found below the permitted exposure limits.

Thesis (Ph.D.)--University of the Witwatersrand, Faculty of Health Sciences, 1997.

This study sought to explore the effects of virtual reality (VR) as a technology that can potentially improve guided meditation practices; VR guided meditation sessions and audio guided meditation sessions were compared. Specifically, this study investigated VR’s impact on an individual’s self-perception of psychological factors that reflect mood or emotion; it also examined VR’s impact on an individual’s self-perception of presence and relaxation. After examination, VR guided meditation had no significant impact on an individual’s self-perception of mood and emotion or self-reported feelings of relaxation. However, guided VR meditation had a significant impact on an individual’s self-reported perception of presence; participants who meditated with VR felt “as if they were at the beach.” Although this study demonstrated that a fairly inexpensive VR system can enhance feelings of presence, that sense of presence did not enhance feelings of well-being and relaxation; this could be attributed to the novelty effect. / 2020-09-06

No description available.

by Chan Chun-wai, Francis. / Thesis (M.Phil.)--Chinese University of Hong Kong, 1993. / Includes bibliographical references (leaves 105-116). / Abstract --- p.I / Acknowledgments --- p.III / Abbreviations --- p.IV / Objectives --- p.VI / Content --- p.VII / Chapter Section 1 --- Introduction / Chapter I. --- Preamble --- p.1 / Chapter II. --- Characteristics of Cell Death Process --- p.1 / Chapter II.1. --- Necrosis --- p.1 / Chapter II.2. --- Apoptosis-Programmed Cell Death --- p.5 / Chapter III. --- Triggering of Programmed Cell Death --- p.10 / Chapter IV. --- DNA Fragmentation and Activation of Endogenous Endonuclease --- p.12 / Chapter V. --- Signal Transduction Leading to Programmed Cell Death --- p.14 / Chapter V.1. --- Role of Calcium Ion --- p.14 / Chapter V.2. --- Role of Protein Kinase C --- p.15 / Chapter V.3. --- Protein Dephosphorylation by Phosphatases --- p.16 / Chapter V.4. --- Role of Adenosine 3':5'-cyclic Monophosphate --- p.17 / Chapter V.5. --- Other Signaling Mechanisms --- p.17 / Chapter VI. --- Gene Regulation in Programmed Cell Death --- p.19 / Chapter VI. 1. --- Gene Expression in Programmed cell death --- p.19 / Chapter VI. 1.1 . --- Tissue Transglutaminase --- p.19 / Chapter VI. 1.2. --- Poly (ADP-ribose) Polymerase --- p.20 / Chapter VI. 1.3. --- Testosterone-Repressed Prostate Message-2 Gene --- p.20 / Chapter VI. 1.4. --- Other Programmed Cell Death Associated Gene Expressions --- p.21 / Chapter VI.2. --- Protooncogene Regulation in Programmed Cell Death --- p.22 / Chapter VI.2.1. --- bcl-2 Expression --- p.22 / Chapter VI.2.2. --- c-myc Expression --- p.23 / Chapter VII. --- Concanavalin A and succinylated Concanavalin A --- p.25 / Chapter VII. 1. --- Physiochemical Characterization --- p.25 / Chapter VII.2. --- Cellular Response to Concanavalin A --- p.29 / Chapter VIII. --- Features of Murine Macrophage Cell Line PU5-1.8 and Normal Macrophages --- p.32 / Chapter Section 2 --- Materials and Methods / Chapter I. --- Materials --- p.33 / Chapter II. --- Cell Culture --- p.33 / Chapter III. --- [Methyl-3H]-Thymidine Incorporation Assay --- p.34 / Chapter IV. --- [Methyl-3H]-Thymidine Release Assay --- p.34 / Chapter V. --- "3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT ) Cell Death Assay" --- p.35 / Chapter VI. --- Identification of Cell Death using DNA Chelating Fluorescence Probes´ؤFluorescent Microscopy and Confocal Laser Microscopy --- p.35 / Chapter VII. --- Analysis of DNA Fragmentation --- p.37 / Chapter VIII. --- Determination of Fluxes by Confocal Laser Microscopy --- p.38 / Chapter IX. --- Determination of PKC Activation by Western Blotting and Immunocytochemistry --- p.39 / Chapter X. --- Statistical Analysis --- p.41 / Chapter Section 3 --- Results / Chapter I. --- Concanavalin A was a Cell Death Causing Agent in PU5-1.8 cells --- p.42 / Chapter I.1 --- Con A Reduced the Cell Proliferation in PU5-1.8 cells --- p.42 / Chapter I.2. --- Con A Exhibited Cytotoxic Effect to PU5-1.8 cells --- p.44 / Chapter I.3. --- Con A Exhibited Cytotoxic Effect on Normal Peritoneal Macrophages --- p.46 / Chapter I.4. --- Succinylated Concanavalin A Showed a Weaker Cytotoxic Effect in the PU5-1.8 cells --- p.46 / Chapter I.5. --- α-D-Methylmannopyranoside Inhibited the Cytotoxic Effect of Con A in PU5-1.8 cells --- p.50 / Chapter I.6. --- FCS Inhibited the Con A-induced cell death of PU5-1.8 cells --- p.52 / Chapter II. --- Concanavalin A was an Apoptosis Causing Agentin PU5-1.8 cells --- p.57 / Chapter II. 1. --- Con A Induced Apoptosis in PU5-1.8 cells --- p.57 / Chapter II. 2. --- Con A Enhanced the Release of DNA in PU5-1.8 cell --- p.63 / Chapter II. 3. --- Con A Induced DNA fragmentation in PU5-1.8 cells --- p.63 / Chapter II.4. --- Cycloheximide Inhibited the Con A-Induced Cell Death in PU5-1.8 cells --- p.67 / Chapter II.5. --- Nicotinamide Inhibited the Con A-Induced Cell Death in PU5-1.8 cells --- p.71 / Chapter III. --- Signaling elicited by Concanavalin A --- p.74 / Chapter III.1. --- Con A Increased Intracellular Free Calcium Ion Concentration of PU5-1.8 cells --- p.74 / Chapter III. 1.1. --- Con A Induced Ca2+ Mobilization in PU5-1.8 cells --- p.74 / Chapter III. 1.2. --- Con A Induced the Ca2+ Influx and Intracellular Ca2+ Mobilization --- p.78 / Chapter III. 1.3. --- BAPTA-AM Inhibited the Ca2+ Mobilization in PU5-1.8 cells Stimulated by Con A --- p.80 / Chapter III.2. --- Role of Protein kinase C --- p.86 / Chapter III.2.1. --- Con A Increased the amount of PKC in PU5-1.8 cells --- p.86 / Chapter III.2.2. --- Con A translocated the Protein Kinase C from Cytosol into Subnuclear Region --- p.86 / Chapter III.2.3. --- The Cell Death Induced by Con A Is Partially Inhibited by PKC Depletion But not by Staurosporine --- p.89 / Chapter Section 4 --- Discussions / Chapter I. --- PU5-1.8 cells as a Model for the Study of Cell Deathin Macrophages --- p.94 / Chapter II. --- Concanavalin A caused Cell Death in PU5-1.8 cells --- p.95 / Chapter III. --- Concanavalin A induced Programmed Cell Death in PU5-1.8 cells --- p.97 / Chapter IV. --- Increase in Intracellular Calcium was not Required in Con A-induced Cell Death --- p.100 / Chapter V. --- Activation of Protein Kinase C was Partially Required for Con A-induced Cell Death --- p.101 / Chapter VI. --- General Discussions --- p.102 / Chapter Section 5 --- Bibliography --- p.104 / Reference --- p.104

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The research area of magnetic field effects (MFE) on organic systems has been intensively studied during the last decade. It has been revealed that there are processes that are subject to low fields (< 50 mT) and processes that are subject to high fields (> 50 mT). While the low field processes are widely accepted to be a result of the suppression of the spin mixing caused by random hyperfine fields and spin-orbit coupling within the devices, the origin of the high field processes is still not clear. Although several mechanisms, like triplet-charge carrier interaction (TCI) and triplet-triplet annihilation (TTA), were proposed to explain the high field MFEs, how these processes are affected by a magnetic field is not well understood. This thesis presents a study of the role of excitons on MFEs using aluminium tris(8-hydroxyquinolinate) (Alq3) based diodes, focusing on the behaviour of high field effects on electroluminescence (MEL). In order to investigate the role of excitons on high field MEL, devices with different structures were designed to modify the population of exciton and excess charge carriers in the devices via controlling the injection of charge carriers. In this way, the exciton population dependent TTA and TCI processes can be studied further and even distinguished, since the TTA depends mainly on the population of triplets while the TCI depends on the exciton to charge carrier ratio. Steady state MFE measurements were performed, and results show that significant high field MEL decay can be seen in a device with extremely low triplet concentration. This indicates that TTA cannot be the underlying mechanism of high field MEL decay. The gradual trend of high field MEL, changing from a moderate increase to significant decays upon adjusting the hole and electron injection from balanced to severely hole dominated, suggests that this high field decay is exciton-hole interaction dependent. To decompose the role of singlets and triplets on high MELs, transient MFE measurements were performed on the Alq3 based standard devices. Since in Alq3 layer singlets feature a lifetime of ~ns and triplets feature a lifetime of ~ms, the behaviour of MEL at the rising edge and the falling edge of a pulse can provide a useful tool. Results show that an extra component occurs in the transient MEL at large current density and high fields. This indicates that the high field MEL is related to triplet-charge carrier interaction.

by Wei-Zai Shen. / Thesis (Ph.D.)--Chinese University of Hong Kong, 1997. / Includes bibliographical references (p. 170-193) / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Mode of access: World Wide Web.

Reducing disease prevalence through selection for host resistance offers a desirable alternative to chemical treatment which is a potential environmental concern due to run-off, and sometimes only offers limited protection due to pathogen resistance for example (Chen et al., 2010). Genetic analyses require large sample sizes and hence disease phenotypes often need to be obtained from field data. Disease data from field studies is often binary, indicating whether an individual became infected or not following exposure to infectious pathogens. In genetic analyses of binary disease data, however, exposure is often considered as an environmental constant and thus potential variation in host infectivity is ignored. Host infectivity is the propensity of an infected individual to infect others. The lack of attention to genetic variation in infectivity stands in contrast to its important role in epidemiology. The theory of indirect genetic effects (IGE), also known as associative or social genetic effects, provides a promising framework to account for genetic variation in infectivity as it investigates heritable effects of an individual on the trait value of another individual. Chapter 2 examines to what extent genetic variance in infectivity/susceptibility is captured by a conventional model versus an IGE model. The results show that, unlike a conventional model, which does not capture the variation in infectivity when it is present in the data, a model which takes IGEs into account captures some, though not all, of the inherent genetic variation in infectivity. The results also show that genetic evaluations that incorporate variation in infectivity can increase response to selection and reduce future disease risk. However, the results of this study also reveal severe shortcomings in using the standard IGE model to estimate genetic variance in infectivity caused by ignoring dynamic aspects of disease transmission. Chapter 3 explores to what extent the standard IGE model could be adapted for use with binary infectious disease data taking account of dynamic properties within the remit of a conventional quantitative genetics mixed model framework and software. The effect of including disease dynamics in this way was assessed by comparing the accuracy, bias and impact for estimates obtained for simulated binary disease data with two such adjusted IGE models, with the Standard IGE model. In the first adjusted model, the Case model, it was assumed that only infected individuals have an indirect effect on their group mates. In the second adjusted IGE model, the Case-ordered model, it was assumed that only infected individuals exert an indirect effect on susceptible group mates only. The results show that taking the disease status of individuals into account, by using the Case model, considerably improves the bias, accuracy and impact of genetic infectivity estimates from binary disease data compared to the Standard IGE model. However, although heuristically one would assume that the Case-ordered model would provide the best estimates, as it takes the disease dynamics into account, in fact it provides the worst. Moreover, the results suggest that further improvements would be necessary in order to achieve sufficiently reliable infectivity estimates, and point to inadequacy of the statistical model. In order to derive an appropriate relationship between the observed binary disease trait and underlying susceptibility and infectivity, epidemiological theory was combined with quantitative genetics theory to expand the existing framework in Chapter 4. This involved the derivation of a genetic-epidemiological function which takes dynamic expression of susceptibility and infectivity into account. When used to predict the outcome of simulated data it proved to be a good fit for the probability of an individual to become infected given its own susceptibility and the infectivity of its group mates. Using the derived function it was demonstrated that the use of a linear IGE model would result in biased estimates of susceptibility and infectivity as observed in Chapters 2 & 3. Following the results of Chapter 4, the derived expression was used to develop a Markov Chain Monte Carlo (MCMC) algorithm in order to estimate breeding values in susceptibility and infectivity in Chapter 5. The MCMC algorithm was evaluated with simulated disease data. Prior to implementing this algorithm with real disease data an adequate experimental design must be determined. The results suggest that there is a trade-off for the ability to estimate susceptibility and infectivity with regards to group size; this is in line with findings for IGE models. A possible compromise would be to place relatives in both larger and smaller groups. The general discussion addresses such questions regarding experimental design and possible areas for improvement of the algorithm. In conclusion, the thesis advances and develops a novel approach to the analysis of binary infectious disease data, which makes it possible to capture genetic variation in both host susceptibility and infectivity. This approach has been refined to make those estimates increasingly accurate. These breeding values will provide novel opportunities for genome wide association studies and may lead to novel genetic disease control strategies tackling not only host resistance but also the ability to transmit infectious agents.

MSc (Nursing), Faculty of Health Sciences, University of the Witwatersrand, 2009 / Anxiety, depressive and post-traumatic stress (PTS) symptoms have been identified in many patients following ICU treatment (Rattray, Johnston & Wildsmith 2005). The Intensive Care Unit (ICU) is a stressful environment and patients may be left with long standing psychological symptoms that impair their quality of life (Scragg, Jones & Fauvel 2001). There is a dearth of research on early assessment of the psychological sequelae following treatment in ICU in South Africa and interventions required to aid in the recovery process. Post-traumatic stress symptoms do not appear to decrease over time after ICU discharge (Jones et al 2001, Rattray et al 2005), indeed they may endure for a number of years (Kapfhammer et al 2004) causing the patients significant suffering. The purpose of this study was to investigate the prevalence of symptoms of anxiety, depression and post-traumatic stress in patients, at their first follow up visit in the outpatient department at a level one academic hospital in Johannesburg, South Africa. A prospective, quantitative, cross-sectional, descriptive format was used to investigate these variables. The total sample number was 98 and the instruments used in the structured interview were the Hospital Anxiety and Depression Scale (HADS) and the Experience After Treatment in ICU –7 (ETIC-7). The prevalence of symptoms of anxiety in this sample population was 48%, depression 28% and post-traumatic stress 32%. Fifty-eight percent of the sample had combined anxiety and depression scores severe enough to have a ‘possible clinical disorder’.