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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

Starch-protein active films for food preservation

Moreno Marro, Olga 05 May 2017 (has links)
The overall objective of the doctoral thesis was the development of starch-based (S) biodegradable active films for food packaging applications, by applying both casting method and thermoprocessing. Different blends of S with protein material have been studied in order to improve the functional properties of the films or confer antimicrobial/antioxidant activity. The following protein materials were used: powder buttermilk (BM); lactoferrin (LF) and/or lysozyme (LZ), and bovine gelatin (BG). Ethyl lauroyl arginate (LAE, E243) was also incorporated as antimicrobial compound. Likewise, S:BG blend films, either with or without LAE, with previously oxidized S, have been studied to enhance the crosslinking of polymer chains and to improve the film properties. The films have been characterized as to their functional properties as packaging material, their antioxidant and/or antimicrobial properties, as well as their capacity for preserving different food systems, in terms of lipid oxidation and microbial spoilage. Blends of S with BM gave rise to films with a heterogeneous structure, in which the formation of a protein gel was observed when BM dispersion was heated with S at 90 ºC for 30 min. The heat treatment promoted an increase in the resistance to break and stretchability of films, together with a decrease in water vapour permeability. Only those films subjected to heat treatment exhibited antioxidant activity, probably due to the release of active peptides as a result of high temperatures. However, no antilisterial activity was observed for any film containing BM. The incorporation of LF and/or LZ into S films, obtained by the casting method, led to a partial compatibility between polymers, thus affecting the microstructure of S films, as well as leading to an rise in the glass transition temperature. Films with proteins were less extensible, especially when LF was incorporated. All of the films tested were effective at controlling the progress of lipid oxidation in pork lard, whereas only films with LF/LZ blend reduced the growth of coliforms in minced pork meat, as a result of their synergistic action. Films based on S and BG blends (1:1) were obtained by both casting method and thermo-processing. Phase separation of both polymers (stratified structure or separated domains of both polymers, respectively) was observed in both cases. The incorporation of LZ, but mainly LAE, into films, enhanced the compatibility between polymers. Thermo-processed films were more permeable to water vapour and oxygen, less rigid and resistant and more stretchable, in comparison with those films obtained by casting. While LAE incorporation improved the water vapour barrier capacity, it worsened the oxygen barrier properties, contrary to the effect produced by LZ. All films with LAE exhibited high antilisterial activity. Films based on oxidized S and BG (1:1), obtained by casting, showed a high polymer compatibility, and crosslinking between the polymer chains occurred due to the carbonyl-amino condensation reaction. As a result, the water uptake ability of the films decreased and the mechanical and barrier properties improved, although film browning was induced due to the formation of Maillard compounds. LAE incorporation implied its involvement in condensation reactions, due to its bi-functional character (carbonyl-amino), thus affecting crosslinking and the film properties. These reactive processes progressed throughout storage time, leading to an increase in the mechanical resistance and browning of the films. The obtained Maillard compounds conferred antimicrobial capacity on the films, which increased as the storage time progressed. The application of blend films of native or oxidized S and BG with LAE, for the purposes of preserving vacuum packaged chicken breast fillets, extended the shelf-life through the inhibition of bacterial growth (total viable counts; psicrotrophic, anaerobic,lactic acid bacteria and coliforms). Samples packaged i / El objetivo general de la presente tesis doctoral se basa en el desarrollo de films activos biodegradables a base de almidón (S) para su aplicación en sistemas de envasado de alimentos, por medio de dos métodos diferentes de obtención, método en húmedo por extensión y secado (casting) y método en seco (termoprocesado). Se estudiaron mezclas de S con diferentes materiales proteicos, con fin de disminuir la alta higroscopicidad de los films de S y su retrogradación a lo largo del tiempo de almacenamiento y mejorar sus propiedades funcionales, así como conferirles actividad antimicrobiana/antioxidante. Los materiales proteicos utilizados fueron los siguientes: suero de mantequilla en polvo (BM); lactoferrina (LF) y/o lisozima (LZ), y gelatina bovina (BG). El etil lauroil arginato (LAE, E243) fue también incorporado como compuesto antimicrobiano. Asimismo, se estudiaron los films mezcla de S con BG, con y sin LAE incorporado, habiendo oxidado previamente el S, para así potenciar el entrecruzado de las cadenas poliméricas y mejorar las propiedades de los films. Estos fueron caracterizados en sus propiedades funcionales como material de envase, sus propiedades antioxidantes y/o antimicrobianas, así como por su capacidad de conservación de diferentes sistemas alimentarios, en términos de su oxidación lipídica y deterioro microbiológico. Las mezclas de S con BM dieron lugar a películas con una estructura heterogénea, en las que se observó la formación de un gel proteico como resultado del calentamiento de la dispersión BM con S a 90 ºC durante 30 min. El tratamiento térmico promovió un aumento de la resistencia a la rotura y extensibilidad de los films, junto con una disminución en la permeabilidad al vapor de agua. Sólo las películas sometidas a tratamiento térmico y homogeneización con cizalla mostraron actividad antioxidante, probablemente debido a la liberación de péptidos activos en consecuencia de la alta temperatura y fuerza de cizalla aplicada Sin embargo, no se observó actividad antilisteria para ninguno de los films con BM. La incorporación de LF y/o LZ en films de S condujo a una compatibilidad parcial entre polímeros, afectando así a la microestructura de los films de S, y produciendo un aumento de la temperatura de transición vítrea y disminución de la capacidad de alargamiento de los films, especialmente cuando se incorporó LF. Todos los films resultaron eficaces en el control del progreso de la oxidación lipídica de la manteca de cerdo, mientras que sólo las películas con mezcla LF/LZ redujeron el crecimiento de coliformes en carne picada de cerdo, como resultado de su acción sinérgica. Los films basados en la mezcla S y BG (1: 1) fueron obtenidos por casting y termo-moldeado y compresión, llevando a la separación de fases entre ambos polímeros (estructura esratificada o separación de dominios de ambos polímeros, respectivamente). La incorporación de LZ, y principalmente de LAE, en los films, aumentó la compatibilidad entre ambos polímeros. Los films termoprensados fueron más permeables al vapor de agua y al oxígeno, menos rígidos y resistentes y más extensibles, en comparación con aquellos obtenidos por casting. La incorporación de LAE mejoró la capacidad de barrera contra el vapor de agua, mientras que incurrió en un empeoramiento de la barrera frente al oxígeno, contrariamente al efecto producido por la LZ. Los films con LAE, moldeados o termoprensados, mostraron una alta eficacia antilisteria. Los films basados en S oxidado y BG (1: 1), fueron obtenidos por casting y mostraron una alta compatibilidad polimérica, lo cual condujo al entrecruzado de las cadenas como resultado de la reacción de condensación carbonilo-amino producida entre ambos polímeros. En consecuencia, la capacidad de absorción de agua de los films disminuyó y se mejoraron las propiedades mecánicas y de barrera, aunque también se indujo a un pardeamiento de los films, indicando / L'objectiu general de la tesi doctoral és el desenvolupament de films actius biodegradables a base de midó (S) per a la seua aplicació en sistemes d'envasat d'aliments, amb l'utitització del mètode d'extensió i assecat (casting) i termoprocessat (barrejat en fos i termo-compressió). Es van estudiar barreges de S amb diferents materials proteics, per millorar les propietats funcionals dels films o conferir activitat antimicrobiana. Els materials protèics utilitzats van ser: sèrum de mantega en pols (BM); lactoferrina (LF) i/o lisozima (LZ), i gelatina bovina (BG). L'ètil lauroil arginat (LAE, E243) va ser també incorporat com a compost antimicrobià. Així mateix, es van estudiar els films barreja de S amb BG, amb i sense LAE, havent oxidat prèviament el S, per potenciar l'entrecreuat de les cadenes polimèriques i millorar les propietats dels films. Aquests van ser caracteritzats en les seues propietats funcionals com a material d'envàs, les seues propietats antioxidants i/o antimicrobianes, així com en la seua capacitat de conservació en diferents sistemes alimentaris, en termes de la seua oxidació lipídica i deteriorament microbià. Les barreges de S amb BM van donar lloc a films amb una estructura heterogènia, en què es va observar la formació d'un gel protèic com a resultat del calfament de la dispersió BM amb S a 90 ºC durant 30 min. El tractament tèrmic va promoure un augment de la resistència al trencament i extensibilitat dels films, juntament amb una disminució en la permeabilitat al vapor d'aigua. Només el films sotmesos a tractament tèrmic van mostrar activitat antioxidant, probablement a causa de l'alliberament de pèptids actius com a conseqüència de l'alta temperatura. No obstant això, no es va observar activitat antilisteria per cap dels films amb BM. La incorporació de LF i/o LZ en films de S obtinguts per casting va donar lloc a una compatibilitat parcial entre polímers, afectant a la microestructura dels films de S, i produint un augment de la temperatura de transició vítria. Els films amb les proteïnes van ser menys extensibles, especialment quan es va incorporar LF. Tots els films van resultar eficaços en el control de l'oxidació lipídica de la mantega de porc, mentre que només el films amb barreja LF/LZ van reduir el creixement de coliforms en carn picada de porc, com a resultat de la seua acció sinèrgica. Els films amb barreges S i BG (1: 1) van ser obtinguts per casting i termo-processat. En tots dos casos es va observar separació de fases entre els dos polímers (estructura estratificada o separació de dominis d'ambdós polímers, respectivament). La incorporació de LZ, i principalment de LAE, en els films, va augmentar la compatibilitat entre tots dos polímers. Els films termo-processats van ser més permeables al vapor d'aigua i l'oxigen, menys rígids i resistents i més extensibles, en comparació amb els obtinguts per càsting. La incorporació de LAE va millorar la capacitat de barrera al vapor d'aigua, a l'hora que va disminuir la capacitat de barrera davant l'oxigen, contràriament a l'efecte produït per la LZ. Tots els films amb LAE, van mostrar una alta capacitat antilisteria. Els films amb S oxidat i BG (1: 1), van ser obtinguts per casting i van mostrar una alta compatibilitat dels polímers, tot produint entrecreuat de les cadenes com a resultat de la reacció de condensació carbonil-amino. En conseqüència, va disminuir la capacitat d'absorció d'aigua dels films i es van millorar les propietats mecàniques i de barrera, encara que es va promoure l'enfosquiment dels films, cosa que indica la formació de compostos de Maillard. La incorporació de LAE va implicar la seua participació en les reaccions de condensació, a causa del seu caràcter bi-funcional (carbonil-amino), el que va afectar a l'entrecreuat i les propietats dels films. Aquests processos reactius van progressar al llarg del temps d'emmagatzematge, donant lloc a un augment de l / Moreno Marro, O. (2017). Starch-protein active films for food preservation [Tesis doctoral no publicada]. Universitat Politècnica de València. https://doi.org/10.4995/Thesis/10251/80616 / TESIS
2

Functionally low-literate consumers' use of food labels in the rural area of Valspan in the Northern Cape of South Africa / Fay Irvine

Irvine, Fay January 2014 (has links)
Functionally low-literate consumers may often struggle to complete everyday adult tasks, such as reading food labels. Food labels are an important source of information for consumers, and assist them to make informed and wise food purchase decisions. However, the manner in which functionally low-literate consumers read, understand and apply this information to their decisionmaking, is different to literate consumers, and minimal research has been conducted regarding functionally low-literate consumers and their use of food labels in South Africa. This study was conducted in a predominantly low-literate and low-income rural area of Valspan, South Africa. Therefore, using food labels to make healthy and financially sound food choices may be considered especially important for this group of consumers. The current study served to conduct an in-depth literature review of functionally low-literate consumers‟ use of food labels in a rural area; explore whether and how functionally low-literate consumers use (read, understand and apply to decision-making) food label information; explore and describe the differences between the demographic characteristics of low-literate consumers and their use (reading, understanding and application) of food labels; make recommendations to educators on how functionally low-literate consumers can improve their use of food labels in a rural area; as well as to make recommendations on how food labels can be adapted to be more user-friendly to functionally low-literate consumers. Data was collected, using 292 interviewer administrated questionnaires, using purposive criterion sampling. The inclusion criteria for respondents were that they: had to be older than 18 years, living in Valspan and must have completed between grades 5 and 8 at school. Data analysis was done, using descriptive statistics, T-tests, ANOVA‟s, Spearman‟s rank order correlations and two-way frequency tables. Effect sizes were taken into consideration for all differences and associations. The results showed that respondents in this study did read food labels. They were also able to understand some simple aspects of the food label, but struggled with other aspects. When respondents struggled to understand food labels, they were selective about who they would ask to assist them, favouring the help of familiar family members and friends. Regarding the respondents‟ ability to apply food label information to their decision-making, respondents were able to identify several store logos, probably due to their tendency to pictorial thinking. Food-related calculations were relatively well completed; however, certain calculation-related terminology was not well understood by respondents. Food label symbols were not well identified, indicating that respondents did not have a good understanding of the meaning of these symbols. Literacy is vital to the use of food labels, as respondents who showed higher literacy levels showed a tendency towards better understanding of food label information, food label symbols and store logos. They also tended to be better equipped to correctly execute product-related calculations. Regarding demographics, respondents who spoke English and Afrikaans and who had a higher income had a tendency to better understand food label information, than respondents who spoke other languages and belonged to lower-income groups. If food labels are adapted, so that even lowliterate consumers are able to efficiently use food labels, they will be able to make informed and wise food product choices. This situation would be beneficial to low-literate and low-income consumers, marketers and retailers, as products with usable labels may consequently become the preferred choice of low-literate consumers and money wary low-income consumers. Additionally, marketers and retailers would be able to capitalise on the mass purchasing power that this target market represents. / M. Consumer Science, North-West University, Potchefstroom Campus, 2014
3

Functionally low-literate consumers' use of food labels in the rural area of Valspan in the Northern Cape of South Africa / Fay Irvine

Irvine, Fay January 2014 (has links)
Functionally low-literate consumers may often struggle to complete everyday adult tasks, such as reading food labels. Food labels are an important source of information for consumers, and assist them to make informed and wise food purchase decisions. However, the manner in which functionally low-literate consumers read, understand and apply this information to their decisionmaking, is different to literate consumers, and minimal research has been conducted regarding functionally low-literate consumers and their use of food labels in South Africa. This study was conducted in a predominantly low-literate and low-income rural area of Valspan, South Africa. Therefore, using food labels to make healthy and financially sound food choices may be considered especially important for this group of consumers. The current study served to conduct an in-depth literature review of functionally low-literate consumers‟ use of food labels in a rural area; explore whether and how functionally low-literate consumers use (read, understand and apply to decision-making) food label information; explore and describe the differences between the demographic characteristics of low-literate consumers and their use (reading, understanding and application) of food labels; make recommendations to educators on how functionally low-literate consumers can improve their use of food labels in a rural area; as well as to make recommendations on how food labels can be adapted to be more user-friendly to functionally low-literate consumers. Data was collected, using 292 interviewer administrated questionnaires, using purposive criterion sampling. The inclusion criteria for respondents were that they: had to be older than 18 years, living in Valspan and must have completed between grades 5 and 8 at school. Data analysis was done, using descriptive statistics, T-tests, ANOVA‟s, Spearman‟s rank order correlations and two-way frequency tables. Effect sizes were taken into consideration for all differences and associations. The results showed that respondents in this study did read food labels. They were also able to understand some simple aspects of the food label, but struggled with other aspects. When respondents struggled to understand food labels, they were selective about who they would ask to assist them, favouring the help of familiar family members and friends. Regarding the respondents‟ ability to apply food label information to their decision-making, respondents were able to identify several store logos, probably due to their tendency to pictorial thinking. Food-related calculations were relatively well completed; however, certain calculation-related terminology was not well understood by respondents. Food label symbols were not well identified, indicating that respondents did not have a good understanding of the meaning of these symbols. Literacy is vital to the use of food labels, as respondents who showed higher literacy levels showed a tendency towards better understanding of food label information, food label symbols and store logos. They also tended to be better equipped to correctly execute product-related calculations. Regarding demographics, respondents who spoke English and Afrikaans and who had a higher income had a tendency to better understand food label information, than respondents who spoke other languages and belonged to lower-income groups. If food labels are adapted, so that even lowliterate consumers are able to efficiently use food labels, they will be able to make informed and wise food product choices. This situation would be beneficial to low-literate and low-income consumers, marketers and retailers, as products with usable labels may consequently become the preferred choice of low-literate consumers and money wary low-income consumers. Additionally, marketers and retailers would be able to capitalise on the mass purchasing power that this target market represents. / M. Consumer Science, North-West University, Potchefstroom Campus, 2014
4

The identification and export promotion of low-carbon environmental goods in South Africa / Antoinette van Niekerk.

Van Niekerk, Antoinette January 2012 (has links)
Economic and environmental objectives are traditionally seen as mutually exclusive, especially in terms of higher economic growth rates that are coupled with higher greenhouse gas emissions. The first aim of this study is to find a possible creative solution, in which higher economic growth can be coupled with lower greenhouse gas emissions, also known as low-carbon growth. The literature review shows that the economic growth aspect of low-carbon growth can be achieved by increasing exports. The other part of low-carbon growth, namely lower greenhouse gas intensity, can be achieved by diffusing low-carbon technologies (or environmental goods). The World Trade Organisation also encouraged the liberalisation of environmental goods. Therefore, low-carbon growth could be achieved by promoting the production and exports of low-carbon environmental goods. Although the World Trade Organisations has encouraged the liberation of environmental goods, there is no official list of environmental goods. Therefore, the second aim of this study is to derive a list of low-carbon environmental goods from existing lists of environmental goods. Thirty-nine lowcarbon environmental goods are identified for the purpose of this study. The Decision Support Model (DSM) is used to identify realistic export opportunities for these environmental goods. These low-carbon environmental goods were ranked based on three criteria: i) their potential environmental benefits, ii) South Africa’s capacity to produce these goods, and iii) their potential economic benefits. The five low-carbon environmental goods that ranked the highest are photosensitive semiconductors (HS-6: 854140), towers and lattice masts (HS-6: 730820), electrical control and distribution boards smaller than 1kV (HS-6: 853710), gearing, ball screws, speed changers, torque converter (HS-6: 848340), and static converters (HS-6: 850440). The exact environmental uses, producers, intensive and extensive export opportunities of the top five goods were discussed. The best overall intensive export opportunities according to potential export value are HS-6: 854140; photosensitive semiconductors (USD 922,362,000) to Germany and HS-6: 853710; electrical control and distribution boards smaller than 1kV, to the United States (USD 838,671,000). The best overall extensive export opportunities according to their potential export value are HS-6: 854140; photosensitive semiconductors to China (USD 953,255,000) and HS-6: 854140; photosensitive semiconductors to Hong Kong (USD 363,505,000). The results of this study will enable policy-makers to make optimal decisions regarding which environmental goods to produce and export. / Thesis (MCom (Economics))--North-West University, Potchefstroom Campus, 2013.
5

The identification and export promotion of low-carbon environmental goods in South Africa / Antoinette van Niekerk.

Van Niekerk, Antoinette January 2012 (has links)
Economic and environmental objectives are traditionally seen as mutually exclusive, especially in terms of higher economic growth rates that are coupled with higher greenhouse gas emissions. The first aim of this study is to find a possible creative solution, in which higher economic growth can be coupled with lower greenhouse gas emissions, also known as low-carbon growth. The literature review shows that the economic growth aspect of low-carbon growth can be achieved by increasing exports. The other part of low-carbon growth, namely lower greenhouse gas intensity, can be achieved by diffusing low-carbon technologies (or environmental goods). The World Trade Organisation also encouraged the liberalisation of environmental goods. Therefore, low-carbon growth could be achieved by promoting the production and exports of low-carbon environmental goods. Although the World Trade Organisations has encouraged the liberation of environmental goods, there is no official list of environmental goods. Therefore, the second aim of this study is to derive a list of low-carbon environmental goods from existing lists of environmental goods. Thirty-nine lowcarbon environmental goods are identified for the purpose of this study. The Decision Support Model (DSM) is used to identify realistic export opportunities for these environmental goods. These low-carbon environmental goods were ranked based on three criteria: i) their potential environmental benefits, ii) South Africa’s capacity to produce these goods, and iii) their potential economic benefits. The five low-carbon environmental goods that ranked the highest are photosensitive semiconductors (HS-6: 854140), towers and lattice masts (HS-6: 730820), electrical control and distribution boards smaller than 1kV (HS-6: 853710), gearing, ball screws, speed changers, torque converter (HS-6: 848340), and static converters (HS-6: 850440). The exact environmental uses, producers, intensive and extensive export opportunities of the top five goods were discussed. The best overall intensive export opportunities according to potential export value are HS-6: 854140; photosensitive semiconductors (USD 922,362,000) to Germany and HS-6: 853710; electrical control and distribution boards smaller than 1kV, to the United States (USD 838,671,000). The best overall extensive export opportunities according to their potential export value are HS-6: 854140; photosensitive semiconductors to China (USD 953,255,000) and HS-6: 854140; photosensitive semiconductors to Hong Kong (USD 363,505,000). The results of this study will enable policy-makers to make optimal decisions regarding which environmental goods to produce and export. / Thesis (MCom (Economics))--North-West University, Potchefstroom Campus, 2013.
6

Low body mass index and the associations with cardiovascular function in Africans : the PURE study / Venter H.L.

Venter, Herman Louwrens January 2011 (has links)
Cardiovascular disease is known as one of the leading causes of mortality worldwide, where low income countries or developing countries have the highest prevalence of cardiovascular disease. One of the main reasons for this statistics is acculturation that leads to changes in behavioral lifestyle and malnutrition within these countries. Low body mass index was found to be an independent risk factor for cardiovascular disease in several studies. From literature it is found that body mass index is lower than the ideal body mass index and is associated with cardiovascular disease. According to Higashi (2003) a body mass index of 22.2 kg/m2 is associated with the lowest morbidity. If body mass index decreases to lower values than the ideal body mass index, a J–curve will be evident suggesting higher prevalence of cardiovascular disease associated with low body mass index. These findings imply that not only high body mass index but also a low body mass index may be a risk factor for cardiovascular disease, morbidity and mortality. Whether low body mass index is associated with cardiovascular risk in an African population remains unclear. Objective: The aim of this study was to investigate the possible associations of low body mass index with variables of cardiovascular function in Africans, with a low socio–economic status. Methodology: This prospective cohort study (N= 2 010) is part of the Prospective Urban and Rural Epidemiology study (PURE) conducted in the North–West Province of South Africa in 2005, where the health transition in urban and rural subjects was investigated within an apparently low socio–economic status group. Our crosssectional PURE sub–study included 496 African people from rural and urban settings, (men, N= 252 and women, N= 244) aged between 35–65 years and body mass index lower than 25 kg/m2. Subjects were sub–divided into two groups. The first group consisted of Africans with a low body mass index smaller or equal to 20 kg/m2 (men; N= 152, women; N= 94) whilst the second group consisted of Africans with a normal body mass index larger than 20 kg/m2 and smaller or equal to 25 kg/m2 (men; N= 100, women; N= 150). Systolic blood pressure and diastolic blood pressure measurements were obtained with the validated OMRON HEM–757 device. The pulse wave velocity was measured using the Complior SP device. Blood was drawn by a registered nurse from the antebrachial vein using a sterile winged infusion set and syringes. Analyses for cholesterol, high density lipoprotein, triglycerides, gamma–glutamyl transferase and high sensitive C–reactive protein were completed utilizing the Konelab 20i. Data analyses were performed using the Statistica 10 program. Statistical analyses were executed to determine significant differences between age, body mass index and lifestyle factors as well as cardiovascular related variables in the different groups. T–tests were used to determine significant differences between independent groups. ANCOVA tests were used to determine BMI group differences independent of age, smoking and alcohol consumption. Partial correlations, which were adjusted for age, smoking and alcohol consumption, determined associations between the BMI groups and cardiovascular variables. Results: Our results indicated significantly higher mean values for the African men, with low body mass index, for cardiovascular variables (Diastolic blood pressure, 88.0 ± standard deviation (SD) 13.4 mmHg; mean arterial pressure, 103.8 ± SD 14.4 mmHg and carotid–radial pulse wave velocity, 12.6 ± SD 2.47 m/s) compared to the normal body mass index group (Diastolic blood pressure, 84.2 ± SD 12.2 mmHg; mean arterial pressure, 100.0 ± SD 13.2 mmHg and carotid–radial pulse wave velocity, 11.6 ± SD 2.00 m/s). The African women with low body mass index had a significant difference for carotid–radial pulse wave velocity (11.3 ± SD 2.43 m/s) compared to the normal body mass index group (10.6 ± SD 2.10 m/s). In African men, after the variables were adjusted for age, smoking and alcohol consumption, we revealed that diastolic blood pressure (88.0 with confidence interval (CI) [86.0– 90.0] mmHg) and carotid–radial pulse wave velocity (12.5 with CI [12.1–12.9] m/s) remained significant higher in the low body mass index group. Additionally, carotidradial pulse wave velocity was negatively associated with body mass index in African men. In the low body mass index group, Pearson and partial correlations of r= – 0.204; p= 0.012 and r= –0.200; p= 0.020 were found respectively in carotid–radial pulse wave velocity. Furthermore, in our unadjusted scatter plot with body mass index versus pulse wave velocity this negative trend of increasing carotid–radial pulse wave velocity with decreasing body mass index was noticeable in both African men and women. Even when carotid–radial pulse wave velocity was adjusted for age, smoking, alcohol consumption, mean arterial pressure and heart rate, a J–curve between carotid–radial pulse wave velocity and body mass index was still evident. Conclusion: A detrimental effect of low body mass index is evident on cardiovascular function in Africans. If body mass index decreases from the optimum value of 22.2 kg/m2 to lower values, a J–curve is evident between body mass index and cardiovascular variables suggesting higher prevalence of cardiovascular disease associated with low body mass index. In our sub–study the carotid–radial pulse wave velocity increases significantly in African men with low body mass index, thus supporting the theory that stiffening of the arteries is evident in Africans with a low body mass index. Low body mass index may contribute to the high prevalence of cardiovascular disease mortality within developing countries and therefore, increase the risk for cardiovascular disease. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2012.
7

Low body mass index and the associations with cardiovascular function in Africans : the PURE study / Venter H.L.

Venter, Herman Louwrens January 2011 (has links)
Cardiovascular disease is known as one of the leading causes of mortality worldwide, where low income countries or developing countries have the highest prevalence of cardiovascular disease. One of the main reasons for this statistics is acculturation that leads to changes in behavioral lifestyle and malnutrition within these countries. Low body mass index was found to be an independent risk factor for cardiovascular disease in several studies. From literature it is found that body mass index is lower than the ideal body mass index and is associated with cardiovascular disease. According to Higashi (2003) a body mass index of 22.2 kg/m2 is associated with the lowest morbidity. If body mass index decreases to lower values than the ideal body mass index, a J–curve will be evident suggesting higher prevalence of cardiovascular disease associated with low body mass index. These findings imply that not only high body mass index but also a low body mass index may be a risk factor for cardiovascular disease, morbidity and mortality. Whether low body mass index is associated with cardiovascular risk in an African population remains unclear. Objective: The aim of this study was to investigate the possible associations of low body mass index with variables of cardiovascular function in Africans, with a low socio–economic status. Methodology: This prospective cohort study (N= 2 010) is part of the Prospective Urban and Rural Epidemiology study (PURE) conducted in the North–West Province of South Africa in 2005, where the health transition in urban and rural subjects was investigated within an apparently low socio–economic status group. Our crosssectional PURE sub–study included 496 African people from rural and urban settings, (men, N= 252 and women, N= 244) aged between 35–65 years and body mass index lower than 25 kg/m2. Subjects were sub–divided into two groups. The first group consisted of Africans with a low body mass index smaller or equal to 20 kg/m2 (men; N= 152, women; N= 94) whilst the second group consisted of Africans with a normal body mass index larger than 20 kg/m2 and smaller or equal to 25 kg/m2 (men; N= 100, women; N= 150). Systolic blood pressure and diastolic blood pressure measurements were obtained with the validated OMRON HEM–757 device. The pulse wave velocity was measured using the Complior SP device. Blood was drawn by a registered nurse from the antebrachial vein using a sterile winged infusion set and syringes. Analyses for cholesterol, high density lipoprotein, triglycerides, gamma–glutamyl transferase and high sensitive C–reactive protein were completed utilizing the Konelab 20i. Data analyses were performed using the Statistica 10 program. Statistical analyses were executed to determine significant differences between age, body mass index and lifestyle factors as well as cardiovascular related variables in the different groups. T–tests were used to determine significant differences between independent groups. ANCOVA tests were used to determine BMI group differences independent of age, smoking and alcohol consumption. Partial correlations, which were adjusted for age, smoking and alcohol consumption, determined associations between the BMI groups and cardiovascular variables. Results: Our results indicated significantly higher mean values for the African men, with low body mass index, for cardiovascular variables (Diastolic blood pressure, 88.0 ± standard deviation (SD) 13.4 mmHg; mean arterial pressure, 103.8 ± SD 14.4 mmHg and carotid–radial pulse wave velocity, 12.6 ± SD 2.47 m/s) compared to the normal body mass index group (Diastolic blood pressure, 84.2 ± SD 12.2 mmHg; mean arterial pressure, 100.0 ± SD 13.2 mmHg and carotid–radial pulse wave velocity, 11.6 ± SD 2.00 m/s). The African women with low body mass index had a significant difference for carotid–radial pulse wave velocity (11.3 ± SD 2.43 m/s) compared to the normal body mass index group (10.6 ± SD 2.10 m/s). In African men, after the variables were adjusted for age, smoking and alcohol consumption, we revealed that diastolic blood pressure (88.0 with confidence interval (CI) [86.0– 90.0] mmHg) and carotid–radial pulse wave velocity (12.5 with CI [12.1–12.9] m/s) remained significant higher in the low body mass index group. Additionally, carotidradial pulse wave velocity was negatively associated with body mass index in African men. In the low body mass index group, Pearson and partial correlations of r= – 0.204; p= 0.012 and r= –0.200; p= 0.020 were found respectively in carotid–radial pulse wave velocity. Furthermore, in our unadjusted scatter plot with body mass index versus pulse wave velocity this negative trend of increasing carotid–radial pulse wave velocity with decreasing body mass index was noticeable in both African men and women. Even when carotid–radial pulse wave velocity was adjusted for age, smoking, alcohol consumption, mean arterial pressure and heart rate, a J–curve between carotid–radial pulse wave velocity and body mass index was still evident. Conclusion: A detrimental effect of low body mass index is evident on cardiovascular function in Africans. If body mass index decreases from the optimum value of 22.2 kg/m2 to lower values, a J–curve is evident between body mass index and cardiovascular variables suggesting higher prevalence of cardiovascular disease associated with low body mass index. In our sub–study the carotid–radial pulse wave velocity increases significantly in African men with low body mass index, thus supporting the theory that stiffening of the arteries is evident in Africans with a low body mass index. Low body mass index may contribute to the high prevalence of cardiovascular disease mortality within developing countries and therefore, increase the risk for cardiovascular disease. / Thesis (M.Sc. (Physiology))--North-West University, Potchefstroom Campus, 2012.
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A study of the current South African housing environment with specific reference to possible alternative approaches to improve living conditions / Louis Gerhardus Lategan

Lategan, Louis Gerhardus January 2012 (has links)
In South Africa issues regarding the dissatisfactory delivery of low-cost housing developments are well known. Low-cost housing has generally been delivered in a manner which attempts to address housing backlogs, instead of focussing on establishing quality environments and sustainable communities. In order to address the current deficient approaches to low-cost residential development, a literature and empirical investigation was conducted with the purpose of exploring the South African status quo. Issues for improvement were researched within the existing knowledge base. The literature reviewed for this study encompassed government literature, policies and legislation as well as work from both national and international authors from a variety of fields, given the diverse nature and multiple impacts related to housing development. These literary works provided evidence to the conclusions drawn and informed the recommendations made accordingly. The empirical research conducted included several structured interviews, the distribution of questionnaires and the evaluation of various South African case studies. Empirical results added a quantitative measure to the evidence provided by the literature study and thus offered further conclusions and recommendations. The recommendations made were categorised according to their contribution to planning, management and design. It is believed that the adoption of these preliminary recommendations may greatly improve the housing delivery process and quality of life experienced by low-income beneficiaries. The issues covered in this study include research, conclusions and recommendations on: * Investigating the South African status quo with regard to housing policies and legislature. * Identifying the merits of historical theoretical models and their value in modern day housing development. * Discussing the importance of a locally focussed development approach with regard to the role of local municipalities versus provincial authorities in low-cost residential development. * Identifying the value of low-cost housing in local economic development and sustainable socio-economic growth. * Discussing the role of community participation in delivering sustainable neighbourhoods and communities. * Investigating the need for higher density development with specific reference to the integration of various housing typologies. * Exploring the relevance and benefits of alternative construction materials in low-cost residential development. * Exploring the informal backyard rental sector. * Exploring the approaches followed in South African case studies of varying successes in various provinces. It should be noted that the research conducted for this study, the conclusions drawn and the recommendations made provide substantial value, but are all mainly provided as preliminary concepts to be elaborated in a future PhD study. / Thesis (MArt et Scien (Urban and Regional Planning))--North-West University, Potchefstroom Campus, 2013
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A study of the current South African housing environment with specific reference to possible alternative approaches to improve living conditions / Louis Gerhardus Lategan

Lategan, Louis Gerhardus January 2012 (has links)
In South Africa issues regarding the dissatisfactory delivery of low-cost housing developments are well known. Low-cost housing has generally been delivered in a manner which attempts to address housing backlogs, instead of focussing on establishing quality environments and sustainable communities. In order to address the current deficient approaches to low-cost residential development, a literature and empirical investigation was conducted with the purpose of exploring the South African status quo. Issues for improvement were researched within the existing knowledge base. The literature reviewed for this study encompassed government literature, policies and legislation as well as work from both national and international authors from a variety of fields, given the diverse nature and multiple impacts related to housing development. These literary works provided evidence to the conclusions drawn and informed the recommendations made accordingly. The empirical research conducted included several structured interviews, the distribution of questionnaires and the evaluation of various South African case studies. Empirical results added a quantitative measure to the evidence provided by the literature study and thus offered further conclusions and recommendations. The recommendations made were categorised according to their contribution to planning, management and design. It is believed that the adoption of these preliminary recommendations may greatly improve the housing delivery process and quality of life experienced by low-income beneficiaries. The issues covered in this study include research, conclusions and recommendations on: * Investigating the South African status quo with regard to housing policies and legislature. * Identifying the merits of historical theoretical models and their value in modern day housing development. * Discussing the importance of a locally focussed development approach with regard to the role of local municipalities versus provincial authorities in low-cost residential development. * Identifying the value of low-cost housing in local economic development and sustainable socio-economic growth. * Discussing the role of community participation in delivering sustainable neighbourhoods and communities. * Investigating the need for higher density development with specific reference to the integration of various housing typologies. * Exploring the relevance and benefits of alternative construction materials in low-cost residential development. * Exploring the informal backyard rental sector. * Exploring the approaches followed in South African case studies of varying successes in various provinces. It should be noted that the research conducted for this study, the conclusions drawn and the recommendations made provide substantial value, but are all mainly provided as preliminary concepts to be elaborated in a future PhD study. / Thesis (MArt et Scien (Urban and Regional Planning))--North-West University, Potchefstroom Campus, 2013
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'n Behoeftebepaling van onderwysers om leerders met 'n lae selfwaarde in 'n klassituasie te akkommodeer / Winette Genis

Genis, Winette January 2013 (has links)
In practice, the learner with low self worth struggles to achieve certain goals and does not experience success in the classroom. Teachers involved in the lives of these learners do not always have the skills to motivate and handle them in the classroom. The general aim and focus of the research study therefore is to identify the needs of educators in a primary school setting in order to accommodate the learner with low self worth in the classroom. The theoretical framework of this study is based on the Gestalt theory, focussing on the phenomenological method of awareness. The researcher made use of a qualitative research approach and the empirical data was collected by means of focus groups. The collected data was analysed by Creswell’s spiral of data analysis. In conclusion, the researcher identified that educators have a need regarding their training, parental involvement, personal and professional support, and a need for a guideline to accommodate the learner with low self worth in the class. In closing, the researcher made some suggestions regarding future training of educators, practice and possible ideas for future research based on the needs of educators identified through this study. / MA (Psychology), North-West University, Potchefstroom Campus, 2014

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