Markov decision processes (MDPs) have proven to be a useful model for sequential decision- theoretic reasoning under uncertainty, yet they require the specification of a reward function that can require sophisticated human judgement to assess relevant tradeoffs. This dissertation casts the problem of specifying rewards as one of preference elicitation and aims to minimize the degree of precision with which a reward function must be specified while still allowing optimal or near-optimal policies to be produced. We demonstrate how robust policies can be computed for MDPs given only partial reward information using the minimax regret criterion. Minimax regret offers an intuitive bound on loss; however, it is computationally intractable in general. This work develops techniques for exploiting MDP structure to allow for offline precomputation that enables efficient online minimax regret computation. To complement this exact approach we develop several general approximations that offer both upper and lower bounds on minimax regret. We further show how approximations can be improved online during the elicitation procedure to balance accuracy and efficiency. To effectively reduce regret, we investigate a spectrum of elicitation approaches that range from the computationally-demanding optimal selection of complex queries about full MDP policies (which are informative, but, we believe, cognitively difficult) to the heuristic selection of simple queries that focus on a small set of reward parameters. Results are demonstrated on MDPs drawn from the domains of assistive technology and autonomic computing. Finally we demonstrate our framework on a realistic website optimization domain, per- forming elicitation on websites with tens of thousands of webpages. We show that minimax regret can be efficiently computed, and develop informative and cognitively reasonable queries that quickly lower minimax regret, producing policies that offer significant improvement in the design of the underlying websites.

Examensarbetets syfte var att undersöka preferenser för olika mellanmålsdrycker, avsedda för skolbarn och som enbart var tillverkad av skånska vegetabilier. Ett ytterligare syfte var att studera lärares uppfattningar av elevernas koncentrationsförmåga under lektionstiden innan lunch. Som ett första led i att utse tre mellanmålsdrycker till ett preferenstest bland skolelever utfördes två konsensusprofileringar. Första profileringen utfördes med experter inom produktutvecklingsområdet där fyra dryckesprototyper profilerades och den andra profileringen utfördes med en studentpanel där 3 vidareutvecklade prototyper profilerades. Preferenstestet utfördes med barn som deltagare för att utse vilken av de tre prototypdryckerna som barnen ansåg som favorit. Favoriten skulle användas till ett projekt vid namn Skolskjutsen. För att ta reda på lärares uppfattning kring elevernas koncentrationsförmåga innan lunch utfördes en kvalitativ mailundersökning med sex deltagande lärare. Resultatet från profileringarna visade att prototyperna skiljde sig från varandra i fråga om egenskaperna utseende, doft, smak och konsistens. De två utvalda mellanmålsdryckerna från profilering 1 var båda söta och mindre sura, den nya framtagna prototypen som profilerades i profilering 2 ansågs både vara för sur och mindre söt i smaken. Preferenstestet visade att barnen signifikant föredrog svartvinbärsdrycken framför mixdrycken i smak, utseende och i helhet. Svartvinbärsdrycken var mer söt och mindre sur i smaken jämfört med mixdrycken. Det var endast ett fåtal av barnen som föredrog mixdrycken som var minst söt och mest sur i smaken.     Slutsatsen av preferenstestet är att majoriteten av barnen i studien föredrog drycker som smakar sött och inte allt för surt. För majoriteten av barnen är det smaken som är den avgörande faktorn. Lärarna anser att barnen är mest koncentrerade på skoldagens start och är minst koncentrerade sent på eftermiddagen. Lärarna som deltog i studien anser även att barnen är hungriga och mindre koncentrerade timmen innan lunch. De undviker att ha mer krävande lektioner som matte och svenska timmen innan lunchen. / The thesis aimed to examine preferences for different snack drinks for school children, and that alone was made from Scania vegetables. A further aim was to study teacher’s perceptions of students' ability to concentrate during class time before lunch. As a first step to appoint three snacks drinks to a preference test among school students were two consensus profiling conducted. First profiling was conducted with experts in the field where four beverage prototypes were profiled and the other profiling was performed with a student panel where three further developed prototypes were profiled. The preference test was conducted with children as participants to select which of the three prototype drinks the children considered favorites. The favorite would be used for a project called Skolskjutsen. To find out the teachers 'perception of students' ability to concentrate before lunch was performed a qualitative email survey with six participating teachers. The results from the profiling have showed that the prototype differed from each other in terms of characteristics appearance, aroma, flavor and texture. The two snack drinks from profiling one was both sweet and less sour, but the new developed prototype which was profiled in profiling 2 considered being too acidic and less sweet in taste. The preference test showed that children significantly preferred the black currant drink before the mix drink in taste, appearance and in full. Blackcurrant drink was sweeter and less acidic in flavor compared to the mix drink. There were only a few of the children who preferred the mix drink that was least sweet and most acidic in taste. The conclusion of the preference test is that the majority of children in the study preferred the beverages that taste sweet and not too acid. For the majority of children, it is the taste that is the determining factor. The teacher’s view that children are most concentrated on the start of the school day and is least concentrated in the late afternoon. The teachers who participated in the study also consider that the kids are hungry and less concentrated the hour before lunch. They avoid having more demanding classes as math and Swedish before lunch. / Skolskjutsen

Same-sex experiences are more prevalent than is thought. Individuals often engage in same-sex behaviours in order to understand their same-sex attractions, which may result in the incorrect integration of a homosexual or bisexual sexual identity. Same-sex behaviour may also lead to feelings of guilt and shame, and can result in confusion regarding sexual identity, which could ultimately influence the successful integration of a sexual identity (a key developmental task during adolescence) and subsequent stages of an individual’s life. This study investigated how young males experienced their sexual identity after having same-sex experiences. In order to better understand these experiences, this study also looked at sexual identity and its development from a psychosocial approach. In addition, this study also took a phenomenological approach into account to better understand how young males understand their same-sex experiences within their socio-cultural context. The qualitative research method was used because it aims to understand how people make sense of their everyday lives and foregrounds participants’ perceptions and experiences. When researching human behaviour, context and behaviour cannot be separated and therefore a phenomenological design was used. The population included five young males who lived in the Boland and Northern suburbs of the Western Cape and who have had same-sex experiences. The participants were selected utilizing the non-probability (convenient purposive) sampling technique, however, the sampling procedure also made use of snowball sampling. Biographically, the participants were between the ages of 18 and 24, and had different sexual orientations. The participants included black and white students who spoke Afrikaans or English, and originated from different provinces in South Africa. Data were collected through a two-part semi-structured interview. The first interview focused on questions about the participants’ sexual preference and identity, same-sex experiences and support system. During the second interview participants were asked to make a collage representing how they viewed their sexual identity with regards to the same-sex experiences they have had. This interview also focused on member checking. The collages and member checking served as forms of triangulation. Data were transcribed and analysed by means of a content analysis that focused on four main categories. These categories corresponded to four main questions that formed part of the first interview. The researcher concluded that each participant experienced his sexual identity and same-sex encounters differently and that none of them experienced the development of their sexual identity as ‘natural’ or as something that was present from birth. They all experienced confusion and conflict about their sexual preference because it was in contrast to their sociocultural context. Same-sex experiences were the result of confusion but also caused confusion and this confusion was mostly experienced in the earlier life stages. More research is needed on the heterosexual identity development of heterosexual identified individuals who have same-sex experiences, so that these individuals can also be accommodated within a sexuality. The development of programmes for therapeutic and/or educational purposes, that focus on the sexual identity and sexual identity development of adolescents, must also be considered in future research. / MA (Psychology), North-West University, Potchefstroom Campus, 2014

This research presents the first North American route-choice model for cyclists developed from a large sample of GPS data. These findings should encourage all interested municipalities to implement cycling as part of their transportation planning by determining key designing and planning factors to encourage cycling. The analysis is based on processing revealed preference data obtained from 415 self-selected cyclists in Waterloo, Ontario, which corresponded to 2000 routes. Cyclists' route decisions were modeled using multinomial logit framework of discrete choice theory. The main finding involved in capturing two different behaviour groups, namely experienced and inexperienced cyclists. This was subsequently reflected in the two developed models. The key factors impacting route-choice were found to be trip length, speed, volume, bicycle lane presence and percent of uphill gradient that cyclists face. The predictive power of the best model was 65%. The outlier analysis found that the relative significance of uphill gradient coefficient in one circumstances and perhaps the exclusion of unobserved variables, in other circumstances could be the cause why probability of actual choice was not predicted by both models all the time. In addition, this research involved in the development of a transferability study involving route-choice modeling for cyclists. The analysis is based on the revealed preference data obtained from 255 self-selected cyclists in Peel Region, Ontario, which corresponded to 425 unique routes. The choice set contained actual routes and a combination of alternatives obtained by labeling and impedance rules. The transferability of Waterloo's model to Peel Region was 37%. This means that cyclists behaviour in the Peel Region can be predicted correctly by travel length, bicycle lane presence and percent of uphill gradient for every third cyclist.

Abstract Previous research has demonstrated that non-contingent reinforcement (NCR) and differential reinforcement of other behaviors (DRO) are effective procedures in reducing problem behavior of children both in and out of the classroom. However, few studies have assessed which procedure is most socially acceptable among teachers. In addition, studies have not recorded data on fidelity of implementation among teachers. A non-concurrent multiple baseline across teachers design was used to (a) demonstrate the effect of NCR and DRO on the problem behaviors of school aged children with no identified developmental disability, and (b) assess implementation fidelity of each procedure by the teacher. This study further assessed which procedure was preferred by teachers by the addition of questionnaires and a choice phase in which teachers ultimately chose which procedure to implement. Results showed that both procedures significantly reduced problem behavior across all participants, with the DRO procedure having the greatest effect. The procedure that was preferred most by teachers varied across participants. One of the three participants preferred the NCR procedure, one preferred the DRO procedure and the last participant gave mixed results between the procedure she said she preferred in the surveys and the procedure she chose to implement in the final choice phase.

A logo lies central in an organisation's visual identity system and it is a way of communicating fundamental aspects about the organisation, such as the organisation personality or the organisation's mission and vision. The logo, or corporate visual identity, could be seen as the organisation's visual shorthand that summarises these fundamental aspects. A design element such as colour can be an expressive tool in terms of visual identity. The use of a particular colour in the logo of an organisation conveys a specific message about that company's identity and personality through the meaning and symbolism that is attached to the colour. The corporate colour scheme of an organisation can also aid in communication without being displayed in context of the visual identity. The combination of both verbal communication such as text, and visual communication such as images, through a design element like colour, could provide an effective method of conveying information. The nature of this study is descriptive. It examined the role played by colour in an organisation's visual identity as a communication tool. The study followed a qualitative approach, making use of a literature study and a case study approach. In the literature study, the role of the graphic designer, the visual identity and a design element like colour in the context of corporate communication were examined. The sources of evidence used for the case study approach, were questionnaires, as well as a colour analysis of the corporate colour schemes of each of the selected case organisations as utilised in their visual identities. The research project attempted to determine the role of colour as communication, as well as the motivation behind the use of a particular colour, should such a motivation exist, and the communication intended behind each colour. The project also attempted to determine the target markets at which the communication is aimed; the research done by each of the case organisations regarding colour symbolism and the suitability of the colour regarding the target markets; and the importance attached to colour as a communication tool. These questions were investigated through the use of the questionnaires. The colour analysis was done to function as a control mechanism to, for example, determine whether the intended message behind colour correlated to the perceived message as determined by the colour analysis. The results from the questionnaires and colour analysis used in the study showed that colour does play an important role in the selected case organisation's visual identities. The results of the study also found, however, that regardless of how important colour was viewed as a method of communication by the respondents, certain factors exist which influence the effectiveness of colour as a communication tool. / Thesis (M.A. (Communication Studies))--North-West University, Potchefstroom Campus, 2004.

The role of brain dominance in the maintenance of learner discipline Recent research in especially Education Law has shown that maintaining discipline in South African schools constitutes a problem for many educators. Research over the last few decades has also indicated a strong link between brain dominance and behaviour. The aim of this research was to establish to what extent the brain dominance of learners and educators influence their attitude towards and perceptions of the implementation of schools' codes of conduct and their resulting behaviour in class. Educators' response to indiscipline was studied against the backdrop of the Constitution, and more specifically the Bill of Rights, as well as other legislation pertaining to learner discipline. The findings revealed a strong link between brain dominance and the behaviour and attitudes of learners and. educators regarding school discipline. It is therefore suggested that the code of conduct should be developed with input from learners and educators from all four quadrants of the brain. Where possible, a measure of flexibility should be included in these documents in the form of incentives for good behaviour and by using discretion when implementing the code of conduct. The insight of educators and learners into the implications of brain dominance was also found to be crucial. / Thesis (M.Ed.)--North-West University, Potchefstroom Campus, 2006.

Living environments are seldom, if ever, devoid of all background auditory stimuli. However, the relationship between particular structural components of acoustic backgrounds and cognitive task performance remains unclear. Two experiments were completed to examine the influence of sound on a visual selective attention task. Participants performed the Stroop task (Stroop, 1935) while silence or background acoustic patterns of various complexities were presented over headphones. No effect of background sound on performance was found. A post-hoc analysis indicated that in comparison with participants who do not regularly listen to music while studying, participants who regularly listen to music while studying performed better on the Stroop task when a structured auditory pattern that included variation in both frequency and time interval was presented in the background. These results indicate that distinct structural components of background auditory sequences may interact with individual characteristics to influence cognitive performance on a task involving selective attention.

Sensorische Asymmetrien zeigen sich vor allem im Bereich der Augen und der Ohren. Es gibt verschiedene Möglichkeiten, diese Asymmetrien zu untersuchen. Hierbei kann man Präferenz-, Leistungstests and sensorische Tests unterscheiden. Im Gegensatz zur Präferenz der Augen wurde die Ohrpräferenz bisher nur wenig berücksichtigt. Das Ziel dieser Studie ist es, einige neue Aspekte zur Untersuchung vorzulegen. Wir konnten in der Literatur insgesamt 13 verschiedene Tests zur Bestimmung der Präferenzohrigkeit nachweisen: «Schublade», «Tischdecke», «Schachtel», «Stoppuhr», «Telefonhörer», «Wandtelefon», «Ohrstecker», «Tür», «Herzschlag», «Taschenradio», «Stimme», «Wand» und «Kopfbewegung». Bei insgesamt 300 Studenten wurde nun die Brauchbarkeit dieser 13 Testproben geprüft. Es konnte eine hohe Beziehung zwischen «Stoppuhr», «Herzschlag», «Tür» und «Schachtel» nachgewiesen werden, nicht jedoch zwischen Telefonieren und Ohrigkeit. Es wird vorgeschlagen, die Ohrigkeit mit einer Testbatterie zu bestimmen, welche vier Testproben umfasst («Stoppuhr», «Herzschlag», «Tür» und «Schachtel»). / Sensory asymmetries are most prominent with respect to the eyes and ears. There are various ways to investigate these asymmetries. The tests used for this purpose can be classified as preference, performance and sensory tests. Contrary to eyedness, earedness has received little attention. The objective of this study is to provide a few new investigatory aspects. We were able to identify 13 different tests for the determination of earedness in the literature: ‘drawer’, ‘tablecloth’, ‘box’, ‘stop watch’, ‘telephone receiver’, ‘wall phone’, ‘earphone’, ‘door’, ‘heartbeat’, ‘transistor radio’, ‘voice’, ‘wall’ and ‘head movement’. A study including 300 student test subjects was done to determine the usefulness of this battery of 13 tests. A high correlation was found between ‘stop watch’, ‘heartbeat’, ‘door’ and ‘box’, but not between telephoning and earedness. The determination of earedness by a battery comprised of 4 tests (‘stop watch’, ‘heartbeat’, ‘door’ and ‘box’) is suggested. / Les asymétries sensorielles se manifestent surtout au niveau des yeux et des oreilles. Il existe plusieurs façons d’étudier des asymétries. On distingue les tests de latéralité, les tests de performance et les tests sensoriels. Contrairement à la latéralité visuelle, la latéralité auditive a été peu étudiée jusqu’ici. Cette étude a pour but de présenter des aspects nouveaux dans ce domaine. Nous avons retrouvé dans la littérature 13 tests au total pour la détermination de la latéralité auditive: «le tiroir», «la nappe», «la boîte», «le chronomètre», «l’écouteur téléphonique», «le téléphone mural», «l’appareil auditif», «la porte», «les battements du coeur», «la radio portative», «la voix», «le mur», «le mouvement de la tête». L’utilité de ces 13 tests a été éprouvée chez 300 étudiants. Une relation significative avec la latéralité a été obtenue pour «le chronomètre », «les battements du coeur», «la porte» et «la boî- te», mais pas pour le téléphone. Les auteurs proposent d’établir la latéralité auditive au moyen d’une batterie de 4 tests: «le chronomètre», «les battements du coeur», «la porte» et «la boîte». / Dieser Beitrag ist mit Zustimmung des Rechteinhabers aufgrund einer (DFG-geförderten) Allianz- bzw. Nationallizenz frei zugänglich.

Das Spurengas Lachgas (N₂O) trägt zur Klimaerwärmung und Zerstörung der Ozonschicht in der Atmosphäre bei. Mit einem Anteil von ca. 70% sind landwirtschaftliche Böden weltweit Hauptverursacher der hohen anthropogenenN₂O Emissionen. N₂O entsteht in Böden durch verschiedene mikrobiologische Prozesse, bei denen N₂O unter anderem aus düngerbürtigem N gebildet wird. Die Entwicklung effektiver Minderungsmaßnahmen wird erst möglich, wenn ein Verständnis der N₂O Quellprozesse und ihrer Dynamik in Böden vorhanden ist. In dieser Studie wurde die Denitrifikation als ein Quellprozess untersucht, der zusammen mit Nitrifikation und Nitrifizierer-Denitrifikation hauptsächlich für die N₂O Emissionen aus Böden verantwortlich ist. Die Denitrifikation beschreibt die Reduktion von Nitrat (NO₃^-) zu N2, wobei Nitrit (NO₂^-), Stickstoffmonoxid (NO) und N₂O Zwischenprodukte dieses Reaktionsweges sind. Lange Zeit galten heterotrophe Bakterien als alleinige Verursacher von N₂O Emissionen aus der Denitrifikation. Im Jahr 1972 wurde allerdings in Versuchen mit Pilzreinkulturen nachgewiesen, dass auch Pilze in der Lage sind, N₂O über die Denitrifikation zu bilden. Zwei Jahrzehnte später wurde gezeigt, dass den meisten Pilzen das Enzym N₂O-Reduktase fehlt. Somit ist nicht N₂, sondern N₂O das hauptsächliche Endprodukt der pilzlichen Denitrifikation. Dies lässt vermuten, dass die Bildung von N₂O durch pilzliche Denitrifikation noch unterschätzt wird, vorausgesetzt Pilze und Bakterien haben ähnliche Prozessraten. Bisher wurde jedoch nicht ausgiebig erforscht, welchen Anteil die einzelnen mikrobiellen Gemeinschaften an der N₂O Bildung tatsächlich haben. Zur Unterscheidung der N₂O Bildungsprozesse in Bezug auf die beteiligten Mikroorganismen stellt die Isotopenanalyse von N₂O eine vielversprechende Anwendung dar. Vor allem die ¹⁵N-Positionspräferenz im N₂O (SP = site preference, d.h. die Differenz zwischen den δ¹⁵N-Werten der außenständigen und zentralen N-Atome im linearen N₂O-Molekül) aus der Denitrifikation zeigte starke Unterschiede zwischen Reinkulturen einiger Bakterien (SP = -11 bis 0 ‰) und zwei untersuchten Pilzen (SP ~ 37 ‰). Jedoch wurden Bakterienreinkulturen bisher ausgiebiger untersucht als Pilzreinkulturen, auch wenn bekannt ist, dass sich die beteiligten Enzyme bei der Denitrifikation, bis auf die NO-Reduktase, zwischen Bakterien und Pilzen nicht unterscheiden. Die verschiedenen NO-Reduktasen sind vermutlich die Ursache für die unterschiedlichen SP-Werte des von Pilzen und Bakterien produzierten N₂O. Des Weiteren wurde bei Bakterien ein Austausch der Sauerstoffatome von Zwischenprodukten der Denitrifikation und dem umgebenden Wasser gefunden, der zwischen 4 und 100% beträgt. Ob es einen solchen Sauerstoffaustausch auch bei Pilzen gibt, ist bisher jedoch unerforscht. Würde der Sauerstoffaustausch bei pilzlicher Denitrifikation nicht erfolgen, ermöglichte dies neben der unterschiedlichen SP eine weitere Unterscheidung der Herkunft des N₂O. Der Sauerstoffaustausch würde signifikante Unterschiede in der O Isotopensignatur im N₂O pilzlicher bzw. bakterieller Herkunft verursachen. In der vorliegenden Studie, die Aufschluss über die pilzliche N₂O Produktion aus der Denitrifikation geben soll, wurden drei Hauptthemen behandelt. In einem Isotopen-Tracerexperiment mit <up>18</sup>O-angereichertem Wasser wurde untersucht, ob bei sechs Pilzreinkulturen ein Sauerstoffaustausch zwischen Wasser und Zwischenprodukten der Denitrifikation stattfindet. Die Pilzreinkulturen zeigten tatsächlich durch Inkorporation von ¹⁸O aus Wasser in N₂O einen Sauerstoffaustausch. Auch Pilze können bis zu 100% des O während der Denitrifikation austauschen. Eine Unterscheidung zwischen der Denitrifikation durch Bakterien und Pilze anhand der Sauerstoffsignatur ist somit nicht möglich. Das zweite Thema sollte Auskunft darüber geben, ob hohe SP-Werte des N₂O aus der Denitrifikation bei Pilzreinkulturen allgemeingültig sind. Neben den zwei bisher untersuchten wurden vier weitere Pilzreinkulturen inkubiert. Diese Studie zeigte für die getesteten Pilzarten ebenfalls höhere SP-Werte (SP = 19.7 bis 32.6 ‰) im Vergleich zum Wertebereich von Bakterienreinkulturen. Basierend auf den Ergebnissen zum Sauerstoffaustausch aus dem Isotopen-Tracerexperiment wurde für die jeweiligen sechs Pilze, anhand der im Rahmen dieses Versuchs ermittelten natürlichen Sauerstoffisotopensignaturen, Mechanismen zur O Isotopenfraktionierung untersucht. Dafür wurden, neben den Werten des Sauerstoffaustausches und der natürlichen O Isotopensignatur der Pilzreinkulturen, Werte für Fraktionierungseffekte aus der Literatur in einem Isotopenfraktionierungsmodell angewendet, um die Beteiligung der verschiedenen Enzyme, die während der Denitrifikation an dem Sauerstoffaustausch beteiligt sind, abzuschätzen. Im Vergleich zu den NO₃^-- und NO-Reduktasen wies die N₂O^--Reduktase einen maßgeblich höheren Sauerstoffaustausch auf. Die Erkenntnisse aus den Experimenten mit den Pilzereinkulturen sollten im Rahmen des dritten Themas auf Ihre Übertragbarkeit auf die mikrobiellen Gemeinschaften in Böden untersucht werden, indem Bodeninkubationsversuche mit selektiver Hemmung der Organismengruppen (Pilze und Bakterien) durchgeführt wurden. Bei dieser Modifizierung der Methode zur Substrat-induzierten Respiration mit selektiver Hemmung (SIRIN) sollte untersucht werden, ob sich die spezifischen SP-Werte für Bakterien und Pilze nach selektiver Wachstumshemmung von Bodengemeinschaften durch spezifische Antibiotika nachweisen lassen. Die Ausprägung des Hemmungseffekts auf SP-Werte in den drei getesteten Böden entsprach nicht den Erwartungswerten, die sich aus den SP-Werten der Pilz- und Bakterienreinkulturen ergaben. Die ermittelten SP-Werte lagen in den meisten Fällen im Bereich jener bakterieller Reinkulturen und eine Hemmung der Bakterien führte in keinem Fall zu der erwarteten Veränderungen der SP-Werte. Folglich konnten die SP-Werte dieser Versuche nicht dazu dienen, die N₂O Bildung in den gehemmten Varianten den verschiedenen Organismengruppen zu zuordnen. Ungeklärt blieb, ob dies durch fehlende Eignung der modifizierten SIRIN-Methode zu erklären ist, oder ob die an Reinkulturen beobachteten SP-Unterschiede zwischen Pilzen und Bakterien nicht auf mikrobielle Gemeinschaften der Versuchsböden übertragbar sind. Im Hinblick auf nach wie vor bestehende methodische Defizite bei der Untersuchung der Pilzdenitrifikation im Boden sollte dies in weitergehenden Studien geklärt werden.