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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
1

Is there a mortality differential by marital status among women in South Africa? a study on a rural sub-district of Mpumalanga Province in the North-East South Africa

Shoko, Mercy 22 September 2009 (has links)
Abstract Using longitudinal data collected between 1999 and 2007, for Agincourt Demographic Surveillance Area, the paper examines the effect of marital status and co-residence on mortality of women who are aged between 20 and 80. The Cox Proportional Hazard Model is used to investigate the relationship between mortality and the covariates; marital status, co-residence, woman’s country of origin and marital duration for married women. The number of months the husband was resident in the ADSA is used as a proxy for coresidence. After controlling for women migration, marital status and co-residence were significant. The divorced/separated and widowed women had a higher probability of dying compared to the married. In addition, being married to a migrant partner increased the woman’s probability of dying. Thus the study concludes that marital status and coresidence affects mortality.
2

Axisymmetric Drop Shape Analysis (ADSA) and Lung Surfactant

Saad, Sameh Mossaad Iskander 11 January 2012 (has links)
The objective of this thesis was to further develop a methodology for surface tension measurement called Axisymmetric Drop Shape Analysisn(ADSA) and to adapt it to studies of lung surfactants, i.e. the material that coats and facilitates the functioning of the lungs of all mammals. The key property of a functioning lung surfactant is its surface tension, which can reach extremely low values. Such values are difficult to measure; but a certain configuration of ADSA, using a constrained sessile drop (ADSA--CSD), is capable of performing such measurements. Clinically, lung surfactant films can be altered from both sides, i.e. from the airspace as well as from the bulk liquid phase that carries the film. Therefore, being able to access the interface from both sides is important. Here, ADSA--CSD was redesigned to be used as a micro film balance allowing access to the interface from both gas- and liquid-side. This allows deposition from the gas side as well as complete exchange of the bulk liquid phase. The new design was used to study lung surfactant inhibition and inhibition reversal. A dynamic compression-relaxation model (CRM) was developed to describe the mechanical properties of lung surfactant films by investigating the response of surface tension to changes in surface area. The model evaluates the quality of lung surfactant preparations -- beyond the minimum surface tension value -- and calculates the film properties, i.e. elasticity, adsorption and relaxation, independent of the compression protocol. The accuracy of the surface tension measurement can depend on drop size. A detailed analysis of drop shapes and accuracy of measured surface tension values was performed using a shape parameter concept. Based on this analysis, the design of ADSA--CSD was optimized to facilitate more accurate measurements. The validity analysis was further extended to the more conventional pendant drop setup (ADSA--PD). An overall upgrade of both hardware and software of ADSA--CSD, together with extensive numerical work, is described and applied to facilitate a more efficient operation. Finally, it is noted that the ADSA--CSD setup developed here can be used for a wide range of colloid and surface chemical applications.
3

Axisymmetric Drop Shape Analysis (ADSA) and Lung Surfactant

Saad, Sameh Mossaad Iskander 11 January 2012 (has links)
The objective of this thesis was to further develop a methodology for surface tension measurement called Axisymmetric Drop Shape Analysisn(ADSA) and to adapt it to studies of lung surfactants, i.e. the material that coats and facilitates the functioning of the lungs of all mammals. The key property of a functioning lung surfactant is its surface tension, which can reach extremely low values. Such values are difficult to measure; but a certain configuration of ADSA, using a constrained sessile drop (ADSA--CSD), is capable of performing such measurements. Clinically, lung surfactant films can be altered from both sides, i.e. from the airspace as well as from the bulk liquid phase that carries the film. Therefore, being able to access the interface from both sides is important. Here, ADSA--CSD was redesigned to be used as a micro film balance allowing access to the interface from both gas- and liquid-side. This allows deposition from the gas side as well as complete exchange of the bulk liquid phase. The new design was used to study lung surfactant inhibition and inhibition reversal. A dynamic compression-relaxation model (CRM) was developed to describe the mechanical properties of lung surfactant films by investigating the response of surface tension to changes in surface area. The model evaluates the quality of lung surfactant preparations -- beyond the minimum surface tension value -- and calculates the film properties, i.e. elasticity, adsorption and relaxation, independent of the compression protocol. The accuracy of the surface tension measurement can depend on drop size. A detailed analysis of drop shapes and accuracy of measured surface tension values was performed using a shape parameter concept. Based on this analysis, the design of ADSA--CSD was optimized to facilitate more accurate measurements. The validity analysis was further extended to the more conventional pendant drop setup (ADSA--PD). An overall upgrade of both hardware and software of ADSA--CSD, together with extensive numerical work, is described and applied to facilitate a more efficient operation. Finally, it is noted that the ADSA--CSD setup developed here can be used for a wide range of colloid and surface chemical applications.
4

Development of Axisymmetric Drop Shape Analysis - No Apex (ADSA-NA)

Kalantarian, Ali 10 January 2012 (has links)
The main purpose of this thesis is the development of a new methodology of contact angle measurement called ADSA-NA (Axisymmetric Drop Shape Analysis - No Apex) that analyzes drop shape configurations with no apex. Thus ADSA-NA facilitates contact angle measurements on drops with a capillary protruding into the drop. This development is desirable because the original ADSA has some limitations for contact angle measurement, and there is a need for the improvement of the accuracy of contact angle measurement. To develop ADSA-NA, a new reference point other than the apex and a new set of optimization parameters different from those of ADSA had to be defined. The three main modules of ADSA had also to be modified; the image analysis, the numerical integration of the Laplace equation for generating theoretical curves, and the optimization procedure. It was shown that ADSA-NA significantly enhances the precision of contact angle and surface tension measurements (by at least a factor of 5) compared to those obtained from sessile drops using ADSA. Computational as well as design aspects of ADSA-NA were scrutinized in depth, well beyond the level of scrutiny in the original ADSA. On the computational side, the results obtained from one and the same drop image were compared using different gradient and non-gradient edge detection strategies and different gradient and non-gradient optimization methods. It was found that the difference between the results of different edge detection strategies is minimal. It was also found that all the optimization methods yield the same answer with eight significant figures for one and the same image. The determination of the location of the solid surface in the drop image was also further refined. On the design side, the effect of controllable experimental factors such as drop height and drop volume on the accuracy of surface tension measurement was studied. It was shown that drop height is the dominant experimental factor, and larger drop heights yield lower surface tension errors.
5

Development of Axisymmetric Drop Shape Analysis - No Apex (ADSA-NA)

Kalantarian, Ali 10 January 2012 (has links)
The main purpose of this thesis is the development of a new methodology of contact angle measurement called ADSA-NA (Axisymmetric Drop Shape Analysis - No Apex) that analyzes drop shape configurations with no apex. Thus ADSA-NA facilitates contact angle measurements on drops with a capillary protruding into the drop. This development is desirable because the original ADSA has some limitations for contact angle measurement, and there is a need for the improvement of the accuracy of contact angle measurement. To develop ADSA-NA, a new reference point other than the apex and a new set of optimization parameters different from those of ADSA had to be defined. The three main modules of ADSA had also to be modified; the image analysis, the numerical integration of the Laplace equation for generating theoretical curves, and the optimization procedure. It was shown that ADSA-NA significantly enhances the precision of contact angle and surface tension measurements (by at least a factor of 5) compared to those obtained from sessile drops using ADSA. Computational as well as design aspects of ADSA-NA were scrutinized in depth, well beyond the level of scrutiny in the original ADSA. On the computational side, the results obtained from one and the same drop image were compared using different gradient and non-gradient edge detection strategies and different gradient and non-gradient optimization methods. It was found that the difference between the results of different edge detection strategies is minimal. It was also found that all the optimization methods yield the same answer with eight significant figures for one and the same image. The determination of the location of the solid surface in the drop image was also further refined. On the design side, the effect of controllable experimental factors such as drop height and drop volume on the accuracy of surface tension measurement was studied. It was shown that drop height is the dominant experimental factor, and larger drop heights yield lower surface tension errors.

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