Thesis (PhD Food Sc)--Stellenbosch University, 2012. / ENGLISH ABSTRACT: The fermentation of milk has been known for millennia and leads to nutritious and prolonged shelf-life dairy products. In Southern Africa, traditional fermented dairy products have the same value as local staple foods and are consumed as a part of or as a whole meal. However, the retail price and the technology make many commercialised fermented dairy products unaffordable to the majority of the population. There is thus a need for a healthy nutritious low-cost easily prepared fermented dairy product. A product that could be the answer to the above need, is Kefir. The principle advantage is that the Kefir beverage is made from reusable Kefir grains, which unfortunately are not easily available and grow slowly. Kefir grains can only be obtained from pre-existing grains, which presents a problem in the marketing of the grains. A mass culturing technique was developed to produce large masses of grains but preparation of Kefir using these grains results in a product (MG Kefir) lacking in the sensory attributes of Traditional Kefir. Thus, the overall objective of this research was to determine the impact of environmental factors on the metabolic profiles of Kefir produced using different Kefir grains and this was then followed by the subsequent enrichment of Kefir prepared with mass cultured grains so as to obtain a Kefir beverage that has improved organoleptic qualities. To determine the impact of environmental factors Traditional and MG Kefir were prepared under controlled and uncontrolled conditions. Traditional Kefir was found to give the best beverage and was thus considered as the control. Under controlled conditions the optimum incubation temperature for the production of Kefir was 22ºC as over-acidification was observed at 25ºC. The metabolic profiles of both Traditional and MG Kefir showed that both contained acetaldehyde, ethanol, acetone, diacetyl and acetic acid. In addition, the metabolic profiles revealed that an inadequate ratio of diacetyl to acetaldehyde as well as the lack of ethyl acetate was responsible for the flavour defect in MG Kefir. In order to overcome this defect, citrate and ascorbate (0.015 % w.v-1) were added during Kefir fermentation to enhance the diacetyl and ethyl acetate production. This addition showed a positive impact on diacetyl but not on ethyl acetate production. Improvement of the overall flavour of Kefir was observed as the ratios of diacetyl to acetaldehyde were higher (0.21 – 0.5) in the samples with added citrate and ascorbate than in the samples without (0.12 – 0.17). The production of ethyl acetate in MG Kefir was enhanced by combining the effects of longer incubation (24 h + 18 h at 22ºC), addition of ethanol and acetic acid at 0.79% (m.v-1) and the addition of either Lactococcus lactis ssp. diacetylactis biovar diacetylactis 318 or Candida kefyr 1283. The best yields were obtained in samples containing C. kefyr 1283 and only added ethanol (9.22 mg.L-1), indicating that ethanol is an important factor in ethyl acetate production by Kefir starter strains and suggesting that the absence of ethyl acetate is an indication that the grains do not contain a yeast capable of producing sufficient ethyl acetate. During this investigation, the impact of ethyl acetate on the organoleptic quality of Kefir during storage at refrigerated and room temperatures were also studied. The results indicated that refrigerated Kefir contained up to 40 mg.L-1 of ethyl acetate and was not found defective and thus ethyl acetate was considered a positive contributor to Kefir flavour. This is of particular interest as ethyl acetate is a potent flavour compound at concentrations below 5 mg.L-1. Improvements of MG Kefir’s flavour were successful and will be of value for commercial Kefir production where the main aim is to optimise the flavour of Kefir. However, stabilising the grain microbial consortium was found to be important as it is responsible, over time, for both stable and acceptable Kefir. Acceptability of Traditional, MG and other Kefirs (Candi-Kefir and Lacto-Kefir) prepared with microbially stabilised MG was evaluated by 85 consumers. Results indicated that pH (r = 0.978; p < 0.05) was a significant driver of liking for flavour, especially for female consumers (r = 0.982; p < 0.05). In addition, three clusters, each characterised by different liking attributes were identified. Cluster I generally disliked all the products whereas slight acidic Kefir such as Candi-Kefir (7.63) and Lacto-Kefir (7.09) were preferred by Cluster III. Cluster II showed preference to Kefir with moderate acidity and high ethanol content. In that regard, Traditional Kefir obtained the best score (7.50) and MG Kefir the lowest score (4.87). The sensory study is of value as it led to the identification of the drivers of consumers liking by the different types of consumers. In the course of this project, near infrared reflectance spectroscopy was developed as a rapid method to estimate lactic and acetic acids, which are the organic acids responsible for acidity in Kefir, as well as pH and titratable acidity (TA). The results showed that the calibration models for lactic acid (RPD = 2.57 – 3.16), pH (RPD = 2.90) and TA (RPD = 2.60) were good for screening purposes (2 < RPD < 3); indicating that these models would show if the concentrations of lactic acid, the pH or the TA varied from the normal range. This study has demonstrated that the flavour of MG Kefir, prepared with enriched grains, was successfully improved and has provided some understanding on the preference liking of Kefir, an unknown fermented dairy product to South African consumers. / AFRIKAANSE OPSOMMING: Die fermentering van melk is al vir millennia bekend en lei tot voedsame suiwelprodukte met 'n verlengde raklewe. In Suidelike Afrika het tradisioneel gefermenteerde suiwelprodukte dieselfde waarde as plaaslike stapelvoedsels en word dit as 'n maaltyd of as deel van 'n maaltyd geëet. Die kleinhandelsprys en tegnologie van kommersieel gefermenteerde suiwelprodukte maak hierdie produkte egter onbekostigbaar vir die grootste deel van die populasie. Daar is dus 'n behoefte aan 'n gesonde, voedsame, goedkoop, maklik-om-te-berei gefermenteerde suiwelproduk. 'n Moontlike produk om aan die bogenoemde te voldoen is Kefir. Die hoof voordeel is dat die Kefir drankie van herbruikbare Kefirkorrels gemaak word, maar ongelukkig is hierdie korrels nie vrylik beskikbaar nie, en vermeerder dit stadig. Kefirkorrels kan net van reeds bestaande korrels verkry word wat problematies is vir die bemarking van hierdie korrels. 'n Massakwekingstegniek is ontwikkel vir die produksie van groot hoeveelhede korrels maar die voorbereiding van Kefir met hierdie korrels lei tot 'n produk (MG Kefir) wat sensories minder aanvaarbaar is as tradisionele Kefir. Die hoofdoel van hierdie navorsing was dus om die invloed van omgewingsfaktore op die metaboliese profiele van Kefir, berei deur gebruik te maak van verskillende Kefirkorrels, te bepaal. Dit is gevolg deur die verryking van Kefir berei van massagekweekte korrels om 'n Kefir drankie met verbeterde organoleptiese kwaliteite te verkry. Tradisionele en MG Kefir is voorberei onder gekontroleerde en ongekontroleerde toestande om die impak van omgewingsfaktore te bepaal. Die beste drankie is van tradisionele Kefir verkry en is dus beskou as die kontrole. Die optimum temperatuur vir die produksie van Kefir onder gekonroleerde toestande is 22ºC aangesien oor-versuring by 25ºC waargeneem is. Die metaboliese profiele van beide tradisionele en MG Kefir het gewys dat beide produkte asetaldehied, etanol, asetoon, diasetiel en asynsuur bevat. Die metaboliese profiele het verder gewys dat 'n onvoldoende diasetiel tot asetaldehied verhouding sowel as 'n tekort aan etielasetaat verantwoordelik was vir 'n geur defek in MG Kefir. Om hierdie defek te oorkom is sitraat en askorbaat (0.015% m.v-1) tydens Kefir fermentasie bygevoeg om diasetiel en etielasetaat produksie te verhoog. Hierdie byvoeging het 'n positiewe effek gehad op diasetiel produksie, maar nie op die produksie etielasetaat nie. 'n Verbetering in die algehele geur van Kefir is waargeneem aangesien die diasetiel tot asetaldehied verhoudings hoër (0.21 – 0.5) was in die monsters met bygevoegde sitraat en askorbaat as in die monsters daarsonder (0.12 – 0.17). Die produksie van etielasetaat in MG Kefir is verhoog deur die effekte van 'n verlengde inkubasie tydperk (24 h + 18 h by 22ºC), die byvoeging van etanol en asynsuur teen 0.79% (m.v-1) en die byvoeging van óf Lactococcus lactis ssp. diacetylactis biovar diacetylactis 318 óf Candida kefyr 1283 te kombineer. Die beste opbrengs is verkry in monsters wat C. kefyr 1283 en slegs etanol (9.22 mg.L-1) bevat het. Dit dui daarop dat etanol 'n belangrike faktor is vir etielasetaat produksie in Kefir beginstamme en wys moontlik op die afwesigheid van etielasetaat wat daarop dui dat die korrels nie 'n gis bevat wat bevoeg is om genoegsame hoeveelhede etielasetaat te produseer nie. Tydens hierdie ondersoek is die impak van etielasetaat op die organoleptiese kwaliteit van Kefir gedurende opberging by verkoelde- en kamertemperatuur ook bestudeer. Die resultate het gewys dat verkoelde Kefir tot 40 mg.L-1 etielasetaat bevat het sonder dat dit defektief was. Etielasetaat is dus beskou as 'n positiewe bydraer in terme van Kefir geur. Dit is van besondere belang aangesien etielasetaat 'n sterk geurkomponent teen konsentrasies laer as 5 mg.L-1 is. Verbeteringe in MG Kefir se geur was suksesvol en sal van waarde wees vir kommersiële Kefir produksie waar die hoofdoel die optimisering van Kefir geur is. Stabilisering van die korrels se mikrobiologiese konsortium is ook belangrik aangesien daar gevind is dat dit oor tyd verantwoordelik is vir stabiele en aanvaarbare Kefir. Die aanvaarbaarheid van tradisioneel, MG en ander Kefirs (Candi-Kefir en Lacto-Kefir), voorberei van mikrobiologies gestabiliseerde MG, is deur 85 verbruikers geëvalueer. Die resultate het aangedui dat pH (r = 0.978; p < 0.05) 'n belangrike faktor is in die bepaling van verbruikers se voorkeur van geur is, veral by vroulike verbruikers (r = 0.978; p < 0.05). Drie groepe, elk gekenmerk deur verskillende voorkeur en aanvaarbaarheid eienskappe, is verder geïdentifiseer. Groep I het oor die algemeen van geen van die produkte gehou nie en Groep III het die effense suur Kefirs soos Candi-Kefir (7.63) en Lacto-Kefir (7.09) verkies. Groep II het die Kefir met 'n matige suurheid en hoë etanolinhoud verkies. Tradisionele Kefir het die hoogste telling (7.50) en MG Kefir die laagste telling (4.78) behaal. Die sensoriese studie is van waarde aangesien dit gelei het tot die identifisering van die drywers van verbruikersvoorkeure deur die verskillende tipes verbruikers. Tydens hierdie projek is 'n naby-infrarooi reflektansie spektroskopiese metode ontwikkel vir die vinnige skatting van melk- en asynsuur, die organise sure wat verantwoordelik is vir die suurheid van Kefir, asook die pH en titreerbare suurheid (TS). Die resultate het getoon dat die kalibrasiemodelle vir melksuur (RPD = 2.57 – 3.16), pH (RPD = 2.90) en TS (RPD = 2.60) voldoende was vir siftingsdoeleindes (2 < RPD < 3). Dit dui daarop dat hierdie modelle sal aandui wanneer die konsentrasie van melksuur, pH of TS afwissel van die normale reeks. Hierdie studie het gewys dat die geur van MG Kefir, berei van verrykte korrels, suksesvol verbeter is en het ook gelei tot insigte in die voorkeur van aanvaarbaarheid van Kefir, 'n onbekende gefermenteerde suiwelproduk vir Suid-Afrikaanse verbruikers.

The concept of Goal Orientations (GOs), which was initially developed in the area of educational psychology, is becoming more and more popular in organisational psychology. Although research on GOs has come a long way since the 1970s there are still a number of conceptual and operational issues which have yet to be addressed. These include issues with the definition, dimensionality, stability and specificity of GOs. It is considered essential to address these concerns because they greatly influence the reliability, validity and accuracy of GO research. Consequently, one aim of this study was to examine the dimensionality, stability and specificity of GOs. It is believed that once enough evidence regarding these issues is gathered this could be used to develop a comprehensive definition of GOs. This study aims to contribute towards gathering such evidence. GOs have been examined both in terms of profiles as well as in terms of individual GO scales (non-profile perspective) in the past. This study uses both perspectives in order to attempt to provide as much information as possible regarding the issues being investigated. Another aim of this study was to investigate the relationships between GOs and performance, mental effort and self-efficacy. Further knowledge of these relationships is considered to be of benefit to organisations. So as to achieve these aims a longitudinal study, consisting of a survey and an experimental study, was carried out. The survey sample consisted of 641 participants whilst the experimental sample was made up of 73 participants. The participants were mainly Loughborough University students. However, there were also a number of employed and retired individuals participating in the study. Quantitative analysis was deemed to be the most appropriate method of analysis to achieve the aims of this study. Data analyses were carried out using SPSS and Latent Gold software packages. The results point towards GOs not being as general and stable as initially assumed. There is a strong possibility of GOs being domain-specific. Consistent with a number of past studies, the approach GOs were found to be more strongly related to self-efficacy, mental effort and performance on tasks than the avoidance GOs. Moreover, the relationships between GOs and these variables seem to be moderated by task characteristics. The profile analyses results revealed that a number of GO profiles obtained in this study were very similar to those obtained in other studies. A closer look at these common GO profiles indicated that some profiles were consistently more strongly related to self-efficacy, mental effort and performance than others. This study provides a foundation for future research studies to build on in order to better understand the nature of GOs and their relationships with self-efficacy, mental effort and performance.

As the ultimate fate of nearly all stars, including our Sun, white dwarfs (WDs) hold rich and informative histories in their observable light. To determine a fundamental parameter of WDs, mass, we perform the first measurement of the average gravitational redshift of an ensemble of WDs. We find a larger mean mass than that determined from the primary and expansive technique known as the spectroscopic method. The potential inaccuracy of this method has broad astrophysical implications, including for our understanding of Type 1a supernova progenitors and for constraining the age of the Universe. This motivates us to investigate the WD atmosphere models used with the spectroscopic method, particularly the input theoretical line profiles, by developing a new experimental platform to create plasmas at WD photospheric conditions (T_e ~ 1 eV, n_e ~ 10^17 cm^-3). Instead of observing WD spectra to infer the plasma conditions at the surface of the star, we set the conditions and measure the emergent spectra in the laboratory. X-rays from a z-pinch dynamic hohlraum generated at the Z Pulsed Power Facility at Sandia National Laboratories irradiate a gas cell to initiate formation of a large (120x20x10 mm or 24 cm^3) plasma. We observe multiple Balmer lines from our plasma in emission and in absorption simultaneously along relatively long (~120 mm) lines of sight perpendicular to the heating radiation. Using a large, radiation-driven plasma aides us to achieve homogeneity along our observed lines of sight. With time-resolved spectroscopy we measure lines at a range of electron densities that spans an order of magnitude, and we do this within one pulsed power shot experiment. Observing our plasma in absorption not only provides the signal-to-noise to measure relative line shapes, it allows us to measure relative line strengths because the lines share the same lower level population. This constrains the theoretical reduction factors used to describe ionization potential depression or the occupation probabilities associated with these Balmer lines. We compare our measured line shapes with the theoretical ones used in WD atmosphere models as part of the first fruits of this rich experimental platform. / text

This thesis focuses on the development of an innovative location-based scheduling methodology and a computer-based model for improving earthwork operations in road construction projects. Analysis of existing planning and scheduling practices in road construction projects conducted in the course of this research concluded that planning, scheduling and resource allocation are largely dependent on subjective decisions. Also, shortcomings exist due to the distinct characteristics of earthworks, e.g. one-off projects with uncertain site conditions and soil characteristics, causing delays and cost overruns of projects. The literature review found that existing linear scheduling methods provide inaccurate location-based information about earthworks and fail to integrate different productivity rates. A survey was used to capture and analyse industrial practices and issues related to delays and cost overruns. This analysis revealed that the accurate location-based information is vital for efficient resource planning and progress monitoring. Following these findings, a theoretical framework and specification were developed to automate location-based scheduling and visualisation of information. A prototype model was developed by integrating road design data, sectional quantities, productivity rates, unit cost, site access points, and arithmetic algorithms. The algorithms underpinning the model enable the generation of time-location plans automatically as a key output of the model. Weekly progress profiles, space congestion plans, and cost S-curves are the other outputs. A cut-fill algorithm was developed to identify optimum quantities of earthwork and its associated costs. Experiments were conducted with design data provided by a road construction company to demonstrate the model‟s functionality. Sensitivity analysis was used to identify the critical factors relating to earthwork scheduling. It was found that the model is capable of generating time-location plans, considering the critical factors and location aspects. Finally, the model was evaluated using a case study and validated by road construction professionals using an indirect comparison method. It was concluded that the model is a valuable tool for producing location-based scheduling, optimising resource planning and assisting in the communication of scheduling information from the location viewpoints in the earthwork projects.

Using a correlational design, this study examined relationships among and between differentiation, profile elevation, gender and educational level (predictors) and depression, confidence, and vocational identity (criterion). Clients presenting for counseling services (n = 90) with a career concern at a large, metropolitan university were included in the study. Six assumptions were examined using three single hierarchical regression analyses to reveal relationships among and between variables. Two research assumptions were confirmed at the .05 level of significance. Bivariate correlations were computed to examine the structure coefficients. Beta weights and structure coefficients were examined to determine the relative contribution of the predictors in the regression model. Results indicated that differentiation, profile elevation, gender and educational level did not predict significant variance in depression and vocational identity. However, differentiation, profile elevation, and educational level did significantly predict confidence (p< .0001).

The work in this thesis mainly focuses on the assessment of density functional methods for computing structures and energies of organic and bioorganic molecules. Previous studies found dramatic conformational and stability changes from B3LYP to MP2 geometry optimization for some Tyr-Gly conformers. Possible reasons could be large intramolecular basis set superposition errors (BSSEs) in the MP2 calculations and the lack of dispersion in the B3LYP calculations. The fragmentation method and three kinds of rotation methods were used to investigate intramolecular BSSE. It is concluded that the rotation method cannot be used to correct intramolecular BSSE along a rotation profile. Another methodology is to employ modern density functionals. We focused on M06-L with the Tyr-Gly conformer ‘book6’. Potential energy profiles were determined by computing the energy for geometries optimized at various fixed values of a distance that controls the degree of foldedness of the structure. M06-L manifested itself as a very promising method to investigate the potential energy surface of small peptides containing aromatic residues. To predict Tyr-Gly structures, 108 potential conformers were created with a Fortran program. The geometry optimizations were done using M06-L/6-31G(d) and M05-2X/6-31+G(d). Two schemes were employed and the most stable conformers were compared to the 20 stable conformers found by B3LYP. Both schemes found 10 conformers similar to one of the B3LYP stable conformers, as well as several newly found conformers. The study of a missing B3LYP stable conformer showed that the possible reason of missing conformers may be the lack in dispersion in B3LYP theory. To study the hydration effect, we studied the conformations of neutral and zwitterionic 3-fluoro-γ-aminobutyric acid (3F-GABA) in solution using different solvation models, mainly the explicit water molecule models. Zwitterionic forms of 3F-GABA are preferred in solution. M06-2X performs better in calculating transition energy profiles than MP2.

The problem of this study is to determine a profile of the typical industrial arts major at North Texas State University, based on scores made on the American College Testing Program Battery, and to compare this profile with profiles of four other local subgroups. ACT scores representing nine categories of student information were analyzed from a total sampling of 286 North Texas State University students of the Industrial Arts Department, School of Business Administration, School of Education, and College of Arts and Sciences. Data were from tests administered during regular ACT testing sessions in 1966-67.

Cette étude propose une approche centrée sur l’activité de l’élève telle que définie et expériencée en cours d’Education Physique et Sportive. Il s’agit d’accéder à ce qui fait sens pour lui/elle lorsque confronté à une situation de résolution de problème, étant entendu que la démarche menée est inductive, participante et internaliste. Le contexte de l’étude se place dans un cycle complet de Course d’Orientation (T = 16h de pratique effective ; 8 séances) mené par un enseignant expert de l’approche réflexive et de l’APSA, auprès d’une classe optionnaire de 19 élèves (âge moyen 17ans ½). Trois études sont menées afin de caractériser le fonctionnement des élèves confrontés à l’épreuve de Baccalauréat et à sa préparation. La première étude porte sur l’analyse de la performance à différents moments du cycle. La seconde étude porte sur les interactions entre profils moteurs, verbaux et réflexifs des élèves à partir des traces écrites de leur activité. La troisième étude s’intéresse, à partir d’un test ante/post cycle inspiré de la théorie des intelligences multiples de Gardner, à cerner l’évolution des capacités déclarées par les élèves. Les résultats montrent que les élèves voient leurs profils évoluer avec une réussite variable au cours du cycle ; ces profils s’expriment en contexte en fonction des situations d’apprentissage, des ressources mobilisées et de l’interprétation des relations carte/milieu naturel. Un suivi de cas permet d’individualiser les résultats qui viennent à la fois questionner la manière dont est abordée l’APSA Course d’Orientation et les stratégies complexes déployées par les élèves / This study focuses on the student’s activity as defined and experienced in Physical Education. The target was to reach what makes sense for him/her when confronted with a problem solving task. The method used an inductive, participative and internalist approach. The study’s context was an optional full learning cycle of Orienteering (T= 16 hours duration; 8 sequences; n = 19 students 17 and half years old) taught by an expert teacher on critical thinking approach and on this sport practice. Three studies are expected to characterize the student functioning when confronted with the Baccalaureat examination and preparation. The first study layed on the analyzis of the performance at different moments of the learning. The second study was on the interactions between student motor, verbal and reflective profiles from the written reports of their activity. The third study was based on the pre/post test inspired from Gardner’ theory of the multiple intelligences: it helped describing the evolution of the declared capabilities of the students. Results showed that student profiles evolve according to a variable success all along the learning cycle; these profiles express within the situated context according to the learning tasks, the mobilized resources and the interpretation of the relationship between the map and the effective natural environment. A case study allowed individualizing the observations so as to question at a time the way Orienteering has to be taught and the complex strategies used by students

This research compared the expenditure patterns, profiles, and trip characteristics of volunteer and leisure tourists in New Orleans. Survey research methods were used to obtain a sample of voluntourists that was compared to a leisure tourist sample obtained from secondary data. Visitors’ expenditures across six types of spending, demographics, and travel information were collected. Data analysis included eight t-tests that revealed that voluntourists’ spending was lower in five out of six categories, total daily expenditures, and total trip spending. Voluntourists spent more on local transportation but preferred cheaper accommodations and dining, seldom gambled, shopped little at the destination, and rarely visited tourist attractions. Frequency analysis used to profile tourists discovered that voluntourists traveled greater distances to the destination than leisure tourists and came from northern states. While most leisure tourists were aged between 35-64 years, married, and neither students nor retired, most voluntourists were younger, single, and still in college.

We present infrared spectroscopy of the classical nova V339 Del, obtained over an similar to 2-yr period. The infrared emission lines were initially symmetrical, with half width half-maximum velocities of 525 km s(-1). In later (t greater than or similar to 77 d, where t is the time from outburst) spectra, however, the lines displayed a distinct asymmetry, with a much stronger blue wing, possibly due to obscuration of the receding component by dust. Dust formation commenced at approximately day 34.75 at a condensation temperature of 1480 +/- 20 K, consistent with graphitic carbon. Thereafter, the dust temperature declined with time as T-d alpha t(-0.346), also consistent with graphitic carbon. The mass of dust initially rose, as a result of an increase in grain size and/or number, peaked at approximately day 100, and then declined precipitously. This decline was most likely caused by grain shattering due to electrostatic stress after the dust was exposed to X-radiation. The appendix summarizes Planck means for carbon and the determination of grain mass and radius for a carbon dust shell.