Showing papers by "University of the Free State published in 2005"
TL;DR: Examples are presented demonstrating that wild-type and genetically engineered strains of Y. lipolytica can be used for alkane and fatty-acid bioconversion, such as aroma production, for production of SCP and SCO, for citric acid production, in bioremediation, in fine chemistry, for steroid biotransformation, and in food industry.
Abstract: The alkane-assimilating yeast Yarrowia lipolytica degrades very efficiently hydrophobic substrates such as n-alkanes, fatty acids, fats and oils for which it has specific metabolic pathways. An overview of the oxidative degradation pathways for alkanes and triglycerides in Y. lipolytica is given, with new insights arising from the recent genome sequencing of this yeast. This includes the interaction of hydrophobic substrates with yeast cells, their uptake and transport, the primary alkane oxidation to the corresponding fatty alcohols and then by different enzymes to fatty acids, and the subsequent degradation in peroxisomal beta-oxidation or storage into lipid bodies. Several enzymes involved in hydrophobic substrate utilisation belong to multigene families, such as lipases/esterases (LIP genes), cytochromes P450 (ALK genes) and peroxisomal acyl-CoA oxidases (POX genes). Examples are presented demonstrating that wild-type and genetically engineered strains of Y. lipolytica can be used for alkane and fatty-acid bioconversion, such as aroma production, for production of SCP and SCO, for citric acid production, in bioremediation, in fine chemistry, for steroid biotransformation, and in food industry. These examples demonstrate distinct advantages of Y. lipolytica for their use in bioconversion reactions of biotechnologically interesting hydrophobic substrates.
564 citations
TL;DR: The NFCS indicated that a large majority of households were food-insecure and that energy deficit and micronutrient deficiencies were common, resulting in a high prevalence of stunting.
Abstract: Objective: The aim of the National Food Consumption Survey (NFCS) in South Africa was to determine the nutrient intakes and anthropometric status of children (1–9 years old), as well as factors that influence their dietary intake. Design: This was a cross-sectional survey of a nationally representative sample of all children aged 1–9 years in South Africa. A nationally representative sample with provincial representation was selected using 1996 Census information. Subjects: Of the 3120 children who were originally sampled data were obtained from 2894, a response rate of 93%. Methods: The sociodemographic status of each household was assessed by a questionnaire. Dietary intake was assessed by means of a 24-hour recall and a foodfrequency questionnaire from the caregivers of the children. Food purchasing practices were determined by means of a food procurement questionnaire. Hunger was assessed by a modified hunger scale questionnaire. Nutritional status was determined by means of anthropometric measurements: height, weight, head circumference and arm circumference. Results: At the national level, stunting (height-for-age below minus two standard deviations ( ,2 2SD) from the reference median) was by far the most common nutritional disorder, affecting nearly one in five children. The children least affected (17%) were those living in urban areas. Even with regard to the latter, however, children living in informal urban areas were more severely affected (20%) compared with those living in formal urban areas (16%). A similar pattern emerged for the prevalence of underweight (weight-for-age ,2 2SD), with one in 10 children being affected at the national level. Furthermore, one in 10 (13%) and one in four (26%) children aged 1–3 years had an energy intake less than half and less than two-thirds of their daily energy needs, respectively. For South African children as a whole, the intakes of energy, calcium, iron, zinc, selenium, vitamins A, D, C and E, riboflavin, niacin, vitamin B6 and folic acid were below two-thirds of the Recommended Dietary Allowances. At the national level, data from the 24-hour recalls indicated that the most commonly consumed food items were maize, sugar, tea, whole milk and brown bread. For South African children overall, one in two households (52%) experienced hunger, one in four (23%) were at risk of hunger and only one in four households (25%) appeared food-secure. Conclusion: The NFCS indicated that a large majority of households were foodinsecure and that energy deficit and micronutrient deficiencies were common, resulting in a high prevalence of stunting. These results were used as motivation for the introduction of mandatory fortification in South Africa.
266 citations
TL;DR: A critical feminist perspective is geared towards addressing the politics of multiple overlapping identities as discussed by the authors, since gender is intertwined with other identities such as race, class and nationality, the dichotomy between universalism and cultural relativism is overcome by connecting individual experiences in a particular location to wider regional and global structures and processes.
Abstract: A feminist perspective can make security discourse more reflective of its own normative assumptions. In respect of an expanded human security concept, a feminist perspective highlights the dangers of masking differences under the rubric of the term ‘human’. A critical feminist perspective is geared towards addressing the politics of multiple overlapping identities. Since gender is intertwined with other identities such as race, class and nationality, the dichotomy between universalism and cultural relativism is overcome by connecting individual experiences in a particular location to wider regional and global structures and processes. An overview of a number of feminist and security-studies schools of thought reveals the extent of universalizing tendencies and gender silences within such discourses. The conceptual and political commensurability of the gender and security constructs is often overlooked. An emphasis on identity politics may thus help to clarify the ambivalence of human security as both a political project of emancipation and an analytical framework. A case is therefore made for more fluid context-based interpretations of gender in human security. In this regard it is posited that alternative feminist approaches, such as those rooted in the African context, could facilitate dialogue within and across supposedly irreconcilable standpoints.
175 citations
TL;DR: In this article, a simple model for intercropping was developed for cereal and legume growth and yield, under semi-arid conditions, based on radiation interception and use, and incorporating a water stress factor.
162 citations
TL;DR: In this paper, the NDVI data derived from the NOAA-Advanced Very Resolution Radiometer (AVHRR) has been used in several countries to forecast crop yields in Swaziland.
154 citations
TL;DR: In this paper, the authors examined the determinants of households' food security using a logistic regression procedure and found that an introduction to fertilizer use and an improvement in the educational levels of household heads lead to a relatively greater probability of food security.
Abstract: The main objective of the study was to examine the determinants of households' food security using a logistic regression procedure. The model was initially fitted with eleven factors, of which six were found to be significant, and all exhibited the expected signs. These include farmland size, ox ownership, fertilizer application, education level of household heads, household size, and per capita production. The result was analyzed further to compute partial effects and to conduct simulation studies on significant determinant factors. Analysis of partial effects revealed that an introduction to fertilizer use and an improvement in the educational levels of household heads lead to relatively greater probability of food security. On the other hand, simulations were conducted on the basis of the base category of farmers, representing food secure households, revealed that both educational levels of household heads and fertilizer application by farmers have relatively high potential to more than double...
154 citations
TL;DR: The overall efficacy of IV amiodarone, as measured by time to success, was dose related but not significantly for any arrhythmia subgroup, including JET, but the subgroups were too small for an accurate assessment.
Abstract: Background— Intravenous (IV) amiodarone has proven efficacy in adults. However, its use in children is based on limited retrospective data. Methods and Results— A double-blind, randomized, multicenter, dose-response study of the safety and efficacy of IV amiodarone was conducted in 61 children (30 days to 14.9 years; median, 1.6 years). Children with incessant tachyarrhythmias (supraventricular arrhythmias [n=26], junctional ectopic tachycardia [JET, n=31], or ventricular arrhythmias [n=4]) were randomized to 1 of 3 dosing regimens (low, medium, or high: load plus 47-hour maintenance) with up to 5 open-label rescue doses. The primary efficacy end point was time to success. Of 229 patients screened, 61 were enrolled during 13 months by 27 of 48 centers in 7 countries. Median time to success was significantly related to dose (28.2, 2.6, and 2.1 hours for the low-, medium-, and high-dose groups, respectively; P=0.028). There was no significant association with dose for any arrhythmia subgroup, including JET,...
154 citations
TL;DR: In this article, the impact of rangeland degradation on soil characteristics (compaction, temperature, soil-water content, infiltrability, root and litter turnover, and the organic matter content), was determined for a semi-arid rangelands.
146 citations
TL;DR: In this article, the authors explored work wellness from a spiritual framework through the construct of meaning in life by focusing on the contribution that a person's sense of meaning can play to improve work wellness and wellness in general.
Abstract: The role of spirituality in the organization is a rapidly growing area of interest in management literature and conferences This resulted in a call for more scientific inquiry into workplace spirituality However, progress with empirical research on spirituality in organizations seems to be hampered by a lack of construct clarity Whilst the construct of workplace spirituality is being clarified, spirituality can be approximated and operationalized through one of its major elements, meaning in life Much knowledge and insights can be gained in the role and relationships of spirituality in organizations through this approach One such postulated relationship with spirituality (meaning in life) is wellness This postulation is based mainly on the results from research studies that consistently show relationships between meaning in life and psychological well‐being As work is also an element of wellness, potential relationships between meaning in life and various aspects of work wellness are explored and conceptualized This paper explores work‐wellness from a spiritual framework through the construct of meaning in life by focusing on the contribution that a person's sense of meaning in life can play to improve work‐wellness and wellness in general A research agenda is developed of postulated relationships of meaning in life with various work wellness related constructs Thirteen research propositions are proposed to provide direction for the empirical inquiry into workplace spirituality
119 citations
TL;DR: The problems facing the pastoralists in the Middle Awash Valley have been created over many years and the solutions will also require time, and sustainable utilisation of the rangeland ecosystem is not possible with the current approach of the communal grazing systems.
112 citations
TL;DR: Heavy grazing proved to be a strong overriding effect of the positive influences of the woody plants, and emphasizes the importance of conservative stocking rates and proper pasture management.
TL;DR: The results of the study confirmed the existence of differences in the soil nutrient status between the various subhabitats, which occurred in a specific spatial gradient from the stem base of the plants towards the open, uncanopied areas.
TL;DR: Oestrous synchronization study on 202 Dorper ewes kept under extensive veld conditions of South Africa during the transition period from the natural breeding to the anoestrus season found no significant differences in terms of oestrous response, time to onset of ostrus and the duration of induced oestrus due to differences in the type of progestagen sponges or time and route of PMSG administration.
TL;DR: In this article, the authors evaluated the risk associated with maize-bean intercropping by quantifying long-term yield in both inter-cropping and sole cropping in a semi-arid region of South Africa (Bloemfontein, Free State) with reference to rainfall variability.
TL;DR: Linked leaf rust and stripe rust resistance genes introduced from Triticum dicoccoides protected common wheat seedlings against a range of pathotypes of the respective pathogens.
Abstract: Linked leaf rust and stripe rust resistance genes introduced from Triticum dicoccoides protected common wheat seedlings against a range of pathotypes of the respective pathogens. The genes were chromosomally mapped using monosomic and telosomic analyses, C-banding and RFLPs. The data indicated that an introgressed region is located on wheat chromosome arm 6BS. The introgressed region did not pair with the ‘Chinese Spring’ 6BS arm during meiosis possibly as a result of reduced homology, but appeared to pair with 6BS of W84-17 (57% of pollen mother cells) and ‘Avocet S’. The introgressed region had a very strong preferential pollen transmission (0.96–0.98) whereas its transmission through egg cells (0.41–0.66) varied with the genetic background of the heterozygote. Homozygous resistant plants had a normal phenotype, were fertile and produced plump seeds. Symbols Lr53 and Yr35 are proposed to designate the respective genes.
TL;DR: The narrow genetic basis among the Ethiopian pungent elongated-fruit cultivars suggests that the pepper breeding program of Ethiopia should focus on enriching its germplasm through local collection and introductions from other parts of the world.
Abstract: Data on genetic similarity among crop cultivars is of vital importance for the plant breeder. The objectives of this study were to group pepper (Capsicum annuum L.) genotypes into clusters according to their distances as estimated by morphological traits and amplified fragment length polymorphism (AFLP) markers and to assess the relationships between the two. Thirty-nine pepper genotypes obtained from different countries were grown in the greenhouse at University of the Free State, South Africa, during 2001 and 2002 in a randomized complete block design with three replications. A total of 20 different morphological traits were measured and six AFLP primer pairs were used to estimate pairwise genetic distances. Both datasets showed high genetic distances among the different genotypes, indicating high genetic diversity among them. The mean genetic distance among Ethiopian pungent elongated-fruit genotypes, was lower than that between them and the introduced ones. Morphological and AFLP distance estimations generally clustered together genotypes with similar fruit sizes. Significant, positive correlation was observed between morphological and AFLP diversity estimations. The narrow genetic basis among the Ethiopian pungent elongated-fruit cultivars suggests that the pepper breeding program of Ethiopia should focus on enriching its germplasm through local collection and introductions from other parts of the world.
TL;DR: Yellow-pigmented, Gram-negative organisms isolated from raw chicken were investigated by means of a polyphasic taxonomic approach and were shown to represent a novel species in the genus Chryseobacterium, for which the name C. vrystaatense sp.
Abstract: Yellow-pigmented, Gram-negative organisms isolated from raw chicken were investigated by means of a polyphasic taxonomic approach and were shown to represent a novel species in the genus Chryseobacterium, for which the name Chryseobacterium vrystaatense sp. nov. is proposed. Its nearest phylogenetic neighbours were Chryseobacterium joostei, Chryseobacterium indologenes and Chryseobacterium gleum, which showed 16S rRNA gene sequence similarity levels of 96·9, 97·1 and 96·1 %, respectively. Levels of DNA–DNA hybridization between strains of C. vrystaatense and Chryseobacterium reference species were below 46 %. Strain LMG 22846T (=CCUG 50970T) was chosen as the type strain and has a DNA G+C content of 37·1 mol%.
TL;DR: The tendency of unpaired meiotic chromosomes to undergo centric misdivision was exploited to translocate leaf rust and stripe rust resistance genes from an Aegilops kotschyi addition chromosome to a group 2 chromosome of wheat.
Abstract: The tendency of unpaired meiotic chromosomes to undergo centric misdivision was exploited to translocate leaf rust and stripe rust resistance genes from an Aegilops kotschyi addition chromosome to a group 2 chromosome of wheat. Monosomic and telosoanic analyses showed that the translocation occurred to wheat chromosome arm 2DL. The introgressed region did not pair with the corresponding wheat 2DL telosome during meiosis suggesting that a whole arm may have been transferred. Female transmission of the resistance was about 55% whereas male transmission was strongly preferential (96%). The symbols Lr54 and Yr37 are proposed to designate the new resistance genes.
TL;DR: In this paper, the relationship between photosynthetically active radiation (PAR) and solar radiation (SR) and between diffuse radiation and global radiation at Bloemfontein, South Africa were investigated.
Abstract: Relationships between photosynthetically active radiation (PAR) and solar radiation (SR) and between diffuse radiation and global radiation at Bloemfontein, South Africa were investigated. The ratio of PAR to SR (PAR/SR) has been reported from many places in the northern hemisphere, but there were not many PAR/SR measurements documented from the southern hemisphere, including the study region. Based on the present observations, mean PAR/SR in the region (0.48) was not exceptionally different from other reported data (0.45–0.50). The effects of sky condition on PAR/SR were also investigated and confirmed the previous findings. PAR/SR increased as the clearness index (KT = ratio of global to extraterrestrial SR) decreased, as sky conditions varied from clear to cloudy. Thus, PAR/SR can be a simple function of the clearness index (the global PAR model). In this study, PAR/SR was explained by a quadratic function of KT. For the relationship between diffuse and global radiation, a simple linear threshold diffuse PAR model, as a linear function of KT, was proposed for the study region using long-term data of diffuse and global SR. Using the previous findings on the relationship between the ratio of diffuse to global SR (KSR) and the ratio of diffuse to global PAR (KPAR), at high KT, KPAR can be estimated as 30% higher than KSR, while at low KTKPAR is equivalent to KSR.
TL;DR: In this article, the seasonal trend in root mass, root distribution with depth and root/shoot ratios along a degradation gradient were quantified over a 2 year period (2000/01 and 2001/02 growing seasons) for a semi-arid rangeland.
TL;DR: The results indicate that oestrous synchronisation with progestagen is efficient and the duration of the induced oestrus is shorter in Nguni does than in Boer goat does, and litter size reduces birth weight and survival rate of indigenous South African goat kids.
TL;DR: The findings suggest that there is a positive relationship between fathers' authoritarian styles and emotion-focused coping strategies in white adolescent learners, in contrast to other researchers found that authoritarian and harsh parental styles are closely related to psychological disturbance.
Abstract: Objective - The aim of this research was to investigate the relationship between perceived parenting styles and resilience in adolescence. Method - The respondents were a sample of 360 English speaking subjects, with a mean age of 17.6 years. Hierarchical regression analyses were used to investigate this relationship. The criterion variables included sense of coherence and problem-focused, emotion-focused and dysfunctional coping strategies. The predictor variables included six scales. Results - Authoritative parenting provided the most significant contribution to the explanation of the variance in resilience for black and white adolescents, and both genders. Surprisingly, the findings suggest that there is a positive relationship between fathers' authoritarian styles and emotion-focused coping strategies in white adolescent learners. In contrast, other researchers found that authoritarian and harsh parental styles are closely related to psychological disturbance. Conclusions - The identified relationships between the criterion and predictor variables found in this study for both black and white adolescents of both genders have distinct and far-reaching implications for envisaged interventions. A future study might also investigate the present study qualitatively. Further research will be necessary to enhance and develop appropriate parenting styles that facilitate resilience in adolescent children. Making use of more sophisticated methodologies, paying greater attention to the interaction between internal and external circumstances and refining theories to make specific predictions about how input variables influence components, should be considered in future.
TL;DR: In this article, the photoluminescence intensity of ZnO nanoparticles was compared with SiO2:Ce 3+ -doped SiO 2 (SiO2 :Ce3+ )a nd encapsulated in SiO1:CE 3+ (ZnO-SiO 2:Cé 3+ ) fabricated from sol-gels.
Abstract: ZnO nanoparticle sw ere synthesized and successfully incorporated in Ce 3+ -doped SiO2 matrix by a sol–gel method. Photoluminescence intensities were compared for ZnO nanoparticles, Ce 3+ -doped SiO2 (SiO2:Ce 3+ )a nd ZnO encapsulated in SiO2:Ce 3+ (ZnO–SiO2:Ce 3+ ) fabricated from sol–gels. Green emission from ZnO associated with anionic oxygen vacancies and blu eb roadband emission due to 5d 1 → 4f 1 transitions in Ce 3+ ions were observed. The photoluminescence intensity of Ce 3+ was enhanced considerably by the energy transfer from ZnO nanoparticles. (Some figures in this article are in colour only in the electronic version)
TL;DR: In this paper, the authors investigated the role of social grants in mitigating the socioeconomic impact of HIV/AIDS in South Africa, using data from a panel study on the household impact of the epidemic.
Abstract: Social grants may play an important role in mitigating the impact of HIV/AIDS. Eligibility for these grants is driven in part by the increasing burden of chronic illness, the mounting orphan crisis and the impoverishment of households associated with the epidemic. This article investigates the role of social grants in mitigating the socio-economic impact of HIV/AIDS in South Africa, using data from a panel study on the household impact of the epidemic. Social grants reduce inequality and decrease the prevalence, depth and severity of poverty in affected households. However, these transfers also have disincentive effects on employment, while non-uptake is in some cases higher amongst the poorest.
TL;DR: In this paper, the authors identify the constraints for livestock marketing by small-scale farmers and provide a new perspective on actionable strategies and implications for agricultural extension that will improve the situation.
Abstract: This paper identifies the constraints for livestock marketing by small-scale farmers. It further provides a new perspective on actionable strategies and implications for agricultural extension that will improve the situation. The development of an efficient livestock marketing system for the small-scale farmers by means of improved extension services and other related aspects are therefore afforded a main focus. A model for the provision of extension services that seeks to address the problem is presented. This model shows that an integrated approach is fundamental to the efficient provision of agricultural extension services which will improve, among other things, farmer productivity and efficiency through adoption and use of technology and practices. The latter is likely to underpin an efficient livestock marketing system within the small-scale livestock sector, thereby increasing possibilities for high market off-take, as well as increased profitability. Keywords : livestock, marketing, communal land, Eastern Cape South African Journal of Agricultural Extension Vol. 34(1) 2005: 81-103
TL;DR: In this paper, the reduction potential for the electrochemically reversible one electron oxidation of the ferrocenyl group varied between 0.304 (for the fctfa complex) and 0.172 (−1.022)V versus Fc/Fc+ in a manner that could be directly traced to the group electronegativities, χR, of the R groups on the β-diketonato ligands, as well as to the p K a ′ values of the free β -diketones.
TL;DR: The most promising development in the control of cervical cancer seems to be vaccination against the human papillomavirus, either as a preventative measure or for stimulating immunity in infected women.
Abstract: Cervical cancer remains the most common malignancy amongst females in countries of low income, mainly due to a lack of screening. Responsible factors are centred around inadequacies of the Pap smear: high cost; low sensitivity; the need of a laboratory with high human expertise; and a demanding logistic system for mass screening. No alternative screening method seems to be clearly advantageous. Although combinations of tests have higher sensitivities, they are complex, costly and associated with low specificities. Adding the problem of effective treatment, it seems that mass screening with adequate coverage of the population is an unreachable goal for many developing countries. The most promising development in the control of cervical cancer seems to be vaccination against the human papillomavirus, either as a preventative measure or for stimulating immunity in infected women.
TL;DR: In this article, an approach based on copulas is proposed and is compared to a model based on the physical behaviour of waves, which is necessary to use multivariate models in order to capture its dependencies.
Abstract: Optimal design of coastal or offshore structures requires the estimation of extreme quantiles of oceanographic data such as wave heights and wave periods. Since there are strong correlations between oceanographic variables, it is necessary to use multivariate models in order to capture its dependencies. To achieve this, an approach based on copulas is proposed and is compared to a model based on the physical behaviour of waves.
TL;DR: In this article, various surface cleaning techniques for the removal of contaminants from GaN were investigated and it was found that surfaces cleaned in (NH4)2S is the best cleaned, have the lowest values of both C and O, RMS roughness and Ga/N ratio.
TL;DR: In this article, seasonal water content fluctuation within the effective root zone was monitored during the growing season for a maize-bean intercrop (IMB), sole maize (SM) and sole bean (SB) in Free State Province, Republic of South Africa.
Abstract: Seasonal water content fluctuation within the effective root zone was monitored during the growing season for a maize-bean intercrop (IMB), sole maize (SM) and sole bean (SB) in Free State Province, Republic of South Africa. Comparisons were undertaken for progressive depths of extraction 0–300 mm; 300–600 mm and 600–900 mm respectively. These enabled the understanding of water extraction behavior of the cropping systems within the different soil layers including the topsoil surface normally influenced by soil surface evaporation. Additive intercrops have been known to conserve water, largely due to the early high leaf area index and the higher total leaf area. In this study, the combined effect of the intercrop components seemed to lower the total water demand by the intercrop compared to the sole crops. During the two seasons (2000/2001 and 2001/2002) the drained upper limit (DUL) and crop lower limits (CLL) were determined. The maize-bean intercrop, sole maize and sole bean had CLL of 141 mm/m, 149 mm/m and 159 mm/m respectively. The DUL was 262 mm/m for the site and therefore the potential plant extractable soil water for the cropping systems were: 121 mm/m (IMB); 114 mm/m (SM) and 103 mm/m (SB). Overall, the intercrop did not have significantly different total soil water extraction during both seasons, although it was additive, showing that it had higher water to biomass conversion.