L’apport principal de cette thèse réside dans l’évaluation de la vulnérabilité d’un certain nombre de règles de voteà la violation de deux propriétés ; nous nous appuyons pour cela sur l’approche axiomatique de la théorie du choixsocial, qui permet d’étudier le comportement d’un mécanisme de choix social vis-à-vis d’un jugement de valeurémis par l’économiste. La symétrie inverse ("reversal symmetry") est la première propriété examinée. A la suite destravaux de Saari [150], nous évaluons deux catégories de règles de vote en prenant cette propriété comme critèrede décision : d’une part, les règles positionnelles simples et d’autre part les règles positionnelles à deux tours. Plusprécisément, nous calculons la probabilité d’occurrence de ce phénomène à la fois en domaine universel (c’est-à-direlorsque les individus peuvent exprimer n’importe quel ordre de préférence), et en domaine restreint (lorsque deshypothèses supplémentaires sont introduites sur la manière dont les votants classent les « candidats » à l’élection).Nous examinons le cas de trois candidats, de quatre candidats ainsi que le contexte d’élections à un très grandnombre de votants, en faisant tendre ce nombre vers l’infini.La seconde thématique est consacrée à l’examen du comportement de la règle de Dodgson face à la propriété d’homogénéité.Nous proposons une méthode de calcul simple et systématique du score de Dodgson. Nous distinguonsensuite différentes classes de profils pour lesquels cette règle est susceptible d’être vulnérable à cette propriété. Afinde compléter notre recherche, des fréquences de violation de cette propriété par la règle de Dodgson sont fournies. / The contribution of this thesis lies in the evaluation of the vulnerability of a number of voting rules to the violationof two properties of the theory of social choice. We rely on the axiomatic approach of social choice theory to examinethe behavior of a social choice procedure according to a value judgment (or axiom) emitted by the economist.Reversal symmetry is the first property studied. Following the works of Saari [150], we evaluate two families ofvoting by using this property as the decision criterion : the simple scoring rules on the one hand, and the scoringrules with runoff on the other hand. We do probability calculations to evaluate how frequent this phenomenon is,in the three-candidate case under universal domain as well as under a restricted domain, and we also tackle thefour-candidate case and the infinite number of voters case.The second topic is devoted to the study of the Dodgsonrule according to the homogeneity axiom. We introduce a simple and systematic method for the computation ofthe Dodgson score. We distinguish various classes of profiles at which that rule may be vulnerable to this property.Further, frequencies of violation of this property by the Dodgson rule are provided.

Sampling of liquid steel to control the steel making process is very important in the steel industry. However, there are numerous types of disposable samplers and no united standard for sampling. The goal in this study is to investigate the effect of slag protection type and sample geometry on sampling parameters and sample homogeneity. Three sample geometries were selected: i) Björneborg ii) Lollipop with a 6 mm thickness and iii) Lollipop with a 12 mm thickness. These sample geometries have been tested with two types of slag protection: metal-cap-protection and argon-protection. The filling velocity and solidification rate of steel samples have been experimentally measured during plant trials. The sample homogeneity with respect to total oxygen content and inclusion size distribution has been determined in different parts of the samples. The study shows that argon-protected samplers have lower, more even, filling velocities (0.19±0.09 m/s) compared to metal-cap-protected samplers (1.28±2.23 m/s). The solidification rate measurements of the different samplers show that the 6 mm thick Lollipop has the highest solidification rate (99~105 °C/s).  Measurements of total oxygen content in argon-protected samples showed little variation between different zones of the samples. However, metal-cap-protected samples contained much higher total oxygen contents. Light optical microscope studies showed that the increase in total oxygen content was probably caused by entrapment of top slag during sampling. Furthermore, it was found that the contamination of top slag in the metal samples increased with a decreased sample weight. Determination of inclusion size distribution in argon-protected Lollipop samples showed that a larger number of primary inclusions are found in the top part compared to the middle and the bottom part of the samples.

Recent years have seen a renewed interest in Variable Speed Limit (VSL) strategies. New opportunities for VSL as a freeway metering mechanism or a homogenization scheme to reduce speed differences and lane changing maneuvers are being explored. This paper examines both the macroscopic and microscopic effects of different speed limits on a traffic stream, especially when adopting low speed limits. To that end, data from a VSL experiment carried out on a freeway in Spain are used. Data include vehicle counts, speeds and occupancy per lane, as well as lane changing rates for three days, each with a different fixed speed limit (80 km/h, 60 km/h, and 40 km/h). Results reveal some of the mechanisms through which VSL affects traffic performance, specifically the flow and speed distribution across lanes, as well as the ensuing lane changing maneuvers. It is confirmed that the lower the speed limit, the higher the occupancy to achieve a given flow. This result has been observed even for relatively high flows and low speed limits. For instance, a stable flow of 1942 veh/h/lane has been measured with the 40 km/h speed limit in force. The corresponding occupancy was 33%, doubling the typical occupancy for this flow in the absence of speed limits. This means that VSL strategies aiming to restrict the mainline flow on a freeway by using low speed limits will need to be applied carefully, avoiding conditions as the ones presented here, where speed limits have a reduced ability to limit flows. On the other hand, VSL strategies trying to get the most from the increased vehicle storage capacity of freeways under low speed limits might be rather promising. Additionally, results show that lower speed limits increase the speed differences across lanes for moderate demands. This, in turn, also increases the lane changing rate. This means that VSL strategies aiming to homogenize traffic and reduce lane changing activity might not be successful when adopting such low speed limits. In contrast, lower speed limits widen the range of flows under uniform lane flow distributions, so that, even for moderate to low demands, the under-utilization of any lane is avoided. These findings are useful for the development of better traffic models that are able to emulate these effects. Moreover, they are crucial for the implementation and assessment of VSL strategies and other traffic control algorithms.

Bakgrund och problem: Forskning kring ägares heterogenitet har lett till att ägare kan kategoriseras efter preferenser och strategier i bolagsstyrningen. Homogeniteten inom ägarkategorierna kan dock ifrågasättas både inom den egna nationella kontexten och över institutionella kontexter. Företagsgrupper är en ägarkategori vars homogenitet särskilt kan ifrågasättas på grund av skillnader i ägarstrukturer mellan länder och i Sverige. Trots det stora inflytande som företagsgrupper har i Sverige är det även en förbisedd och understuderad ägarkategori som med problematik kopplas ihop med familjeägande. Syfte: Att förklara företagsgruppers strategier och beteenden för att avgöra om dessa utgör en homogen ägartyp inom den svenska kontexten. Metod: Undersökningen med utgångspunkt i år 2021 har en deduktiv ansats med modeller som utvecklas utifrån tidigare forskning om ägartyper och dess beteende. Modellerna ifrågasätts dock genom liknande forskning med kontrasterande slutsatser. Slutsats: Företagsgrupper bör inte behandlas som synonymt med familj eftersom åtskiljande prefenser för styrelseersättning pekar på skillnader mellan ägartyperna. Företagsgrupper är homogena på gruppnivå när det gäller dess preferenser för ägaroberoende och styrelseersättning. På sfärnivå upptäcks dock en heterogenitet bland sfärerna i form av avvikande preferenser för styrelseersättning. / Background and problem: Research into the heterogeneity of owners has led to owners being categorized according to preferences and strategies in corporate governance. However, the homogeneity within the ownership categories can be questioned both within the own national context and across institutional contexts. Business groups are an ownership category whose homogeneity especially can be questioned due to differences in ownership structures between countries and in Sweden. Despite the major influence that business groups have in Sweden, it is an overlooked and understudied ownership category that is problematically linked to family ownership. Purpose: To explain the strategies and behaviors of business groups to determine whether these constitute a homogenous ownership type within the Swedish context Method: The study, which examines the year 2021, has a deductive approach with models that are developed based on previous research on owner types and their behavior. However, the models are questioned by similar research with contrasting conclusions. Conclusion: Business groups should not be treated as synonymous with family ownership because deviant preferences for board compensation point to differences between the ownership types. Business groups are homogeneous at the group level in terms of their preferences for board independence from owners and board compensation. At sphere level, however, a heterogeneity is detected among the spheres in the form of deviant preferences for board remuneration.

People read for various purposes like learning specific skills, acquiring foreign languages, and enjoying the pure reading experience, etc. This kind of pure enjoyment may credit to many aspects, such as the aesthetics of languages, the beauty of rhyme, and the entertainment of being surprised by what will happen next, the last of which is typically featured in fictional narratives and is also the main topic of this project. In other words, “good” fiction may be better at entertaining readers by baffling and eluding their expectations whereas “normal” narratives may contain more cliches and ready-made sentences that are easy to predict. Therefore, this project examines whether “good” fiction is less predictable than “normal” fiction, the two of which are predefined as canonized and non-canonized.  The predictability can be statistically reflected by the probability of the next words being correctly predicted given the previous content, which is then further measured in the metric of perplexity. Thanks to recent advances in deep learning, language models based on neural networks with billions of parameters can now be trained on terabytes of text to improve their performance in predicting the next unseen texts. Therefore, the generative pre-trained modeling and the text generator are combined to estimate the perplexities of canonized literature and non-canonized literature.  Due to the potential risk that the terabytes of text on which the advanced models have been trained may contain book content within the corpus, two series of models are designed to yield non-biased perplexity results, namely the self-trained models and the generative pre-trained Transformer-2 models. The comparisons of these two groups of results set up the final hierarchy of architecture constituted by five models for further experiments.  Over the process of perplexity estimation, the perplexity variance can also be generated at the same time, which is then used to denote how predictability varies across sequences with a certain length within each piece of literature. Evaluated by the perplexity variance, the literature property of homogeneity can also be examined between these two groups of literature.  The ultimate results from the five models imply that there lie distinctions in both perplexity values and variances between the canonized literature and non-canonized literature. Besides, the canonized literature shows higher perplexity values and variances measured in both median and mean metrics, which denotes that it is less predictable and homogeneous than the non-canonized literature.  Obviously, the perplexity values and variances cannot be used to define the literary quality directly. However, they offer some signals that the metric of perplexity can be insightful in the literary quality analysis using natural language processing techniques.

Philosophiae Doctor - PhD / The major objective of this study was to investigate the nature of the relationship between achievement motivation, autonomous and social achievement values, study habits and attitudes, locus of control and socio-economic status (SES) as independent variables on the one hand and the level of achievement as dependent variable on the other. The subjects were 548 second and third year social science students who were studying in seven different directions at the University of the Western Cape during 1990. The following measuring instruments were used in the investigation: The Ray-Lynn (1980) Achievement Orientation questionnaire; Strumpfer's (1975) questionnaire for the measuring of autonomous and social achievement values; Rotter's (1966) internal/external locus of control scale, as adapted by Collins (1974); The study habits and attitudes subscales of the Brown and Holtzman (1955) Survey of Study Habits and Attitudes (SSHA) questionnaire, as adapted for South African conditions; A brief biographical questionnaire The achievement criterion consisted of the average achievement point, which is constituted of a proportion of achievement obtained in continuous evaluation, and a proportion of achievement obtained in the final examination. The following findings were made: Achievement motivation plays a much smaller role in achievement than can be expected and its influence is gender specific. It explains only about 5% of the variance in the achievement of males, and non in the case of females. Academically successful and unsuccessful students could also not be distinguished from each other in terms of level of achievement motivation. The measuring instrument for achievement motivation, although valid and reliable, probably does not succeed in measuring aspects of achievement motivation which are related to a specific situation such as the academic. While social achievement value is not related to achievement, autonomous achievement value explains 4,8% of the variance in achievement of males but none in the case of females. Successful and unsuccessful students also do not differ from each other with regard to their achievement value orientation. Study habit and attitude do not differ in their ability to predict the achievement criterion and explain 4,1% and 5,3% of the variance in achievement of males respectively, but none in the case of females. Successful and unsuccessful students can be distinguished in terms of their study habits and attitudes. Socio-economic status has a differential influence on achievement. While higher SES females achieve at a higher level than low SES females, males do not differ in this regard. The subjects are predominantly internally orientated as far as locus of control characteristic is concerned. Although internal individuals display more "positive" characteristics compared to external individuals, the two groups do not, however, differ as far as level of achievement is concerned, irrespective of gender or socio-economic status. African students have a more positive attitude towards study compared to English and Afrikaans speaking, as well as bilingual (English and Afrikaans speaking) students. Females in this study are generally more homogenous than males. It is recommended that: The suitability of the average achievement point as a criterion of achievement be studied; A broad investigation be launched into practices and problems which might centre around the system of continuous evaluation at uwc, with specific reference to possible problems that students, lecturers and big departments may experience; The nature of differences which might exist between higher and low SES female, and low SES female and low SES male students be investigated; The nature of debilitating factors which affect the achievement of low SES female students be investigated; The tendency towards greater homogeneity among female influence thereof on university study; The adjustment of African students at uwc be studied with the objective of identifying factors that obstruct their academic progress

The speech recognition threshold (SRT) is an important measure, as it validates the pure-tone average (PTA), assists in the diagnosis and prognosis of hearing impairments, and aids in the identification of non-organic hearing impairments. Research has shown that in order for SRT testing to yield valid and reliable measures, testing needs to be performed in the patient's native language. There are currently no published materials for SRT testing in the Samoan language. As a result, audiologists are testing patients with English materials or other materials not of the patient's native language. Results produced from this manner of testing are confounded by the patient's vocabulary knowledge and may reflect a language deficit rather than a hearing loss. The present study is aimed at developing SRT materials for native speakers of Samoan to enable valid and reliable measures of SRT for the Samoan speaking population. This study selected 28 trisyllabic Samoan words that were found to be relatively homogeneous in regard to audibility and psychometric function slope. Data were gathered on 20 normal hearing native speakers of Samoan and the intensity of each selected word was adjusted to make the 50% performance threshold of each word equal to the mean PTA of the 20 research participants (5.33 dB HL). The final edited words were digitally recorded onto compact disc to allow for distribution and use for SRT testing in Samoan.

Diese Dissertation entwickelt neue lokal adaptive Methoden zur Schaetzung und Vorhersage von Zeitreihendaten. Diese Methoden sind fuer die Volatilitaetsschaetzung von Finanzmarktrenditen und fuer Regressions- und Autoregressionsprobleme konstruiert worden. Die vorgeschlagenen Ansaetze werden als lokal adaptiv bezeichnet, denn, anstatt einen globalen datenerzeugenden Prozess aufzuzwingen, welcher durch eine endliche Anzahl von Parametern beschrieben werden kann, nehmen sie nur an, dass Beobachtungen, welche chronologisch nah bei einander liegen, durch einen konstanten Prozess gut approximiert werden koennen. Diese Prozeduren sind adaptiv, weil sie fuer jede Beobachtung in einer datengesteuerten Art und Weise das Intervall der Zeithomogenitaet,d.h. die Anzahl der chronologisch benachbarten und homogen vergangenen Daten, aussuchen, fuer welchen die Hypothese einer konstanten Struktur nicht verworfen werden kann. Nichtasymptotische theoretische Ergebnisse werden hergeleitet, welche die Optimalitaet der betrachteten Algorithmen zeigen. Vergleiche mit Standardansaetzen verdeutlichen, dass die neuen Prozeduren sich kompetitiv verhalten und eine nuetzliche Alternative bieten, ausserdem liefern intensive Simulationsstudien und Anwendungen an reellen Daten gute Ergebnisse und bezeugen dabei ihre Effektivitaet und praktische Relevanz. / This thesis develops new locally adaptive methods for estimation and forecasting of financial time series data. These methods are mainly tailored for volatility estimation of financial returns and for regression and autoregression problems. The proposed approaches are defined locally adaptive because instead of imposing a stationary data generating process which can be globally described by a finite number of parameters, they only assume that observations which are chronologically close to each other can be well approximated by a constant process. These procedures are adaptive in the sense that for each observation they choose in a data driven way the interval of time homogeneity, i.e. the number of chronologically close and homogeneous past data where the hypothesis of a constant structure can not be rejected. Nonasymptotic theoretical results are derived, which show the optimality of the suggested algorithms. Comparisons with standard approaches demonstrate that the new procedures behave competitively and offer a valuable alternative, furthermore, intensive simulation studies and applications to real data provide good results, confirming their effectiveness and practical relevance.

Cell motility under physiological and pathological conditions including malignant progression of cancer and subsequent metastasis are founded on environmental confinements. During the last two decades, three-dimensional cell migration has been studied mostly by utilizing biomimetic extracellular matrix models. In the majority of these studies, the in vitro collagen scaffolds are usually assumed to be homogenous, as they consist commonly of one specific type of collagen, such as collagen type I, isolated from one species. These collagen matrices should resemble in vivo extracellular matrix scaffolds physiologically, however, mechanical phenotype and functional reliability have been addressed poorly due to certain limitations based on the assumption of homogeneity. How local variations of extracellular matrix structure impact matrix mechanics and cell migration is largely unknown. Here, we hypothesize that local inhomogeneities alter cell movement due to alterations in matrix mechanics, as they frequently occur in in vivo tissue scaffolds and were even changed in diseased tissues. To analyze the effect of structural inhomogeneities on cell migration, we used a mixture of rat tail and bovine dermal collagen type I as well as pure rat and pure bovine collagens at four different concentrations to assess three-dimensional scaffold inhomogeneities. Collagen type I from rat self-assembled to elongated fibrils, whereas bovine collagen tended to build node-shaped inhomogeneous scaffolds. We have shown that the elastic modulus determined with atomic force microscopy in combination with pore size analysis using confocal laser scanning microscopy revealed distinct inhomogeneities within collagen matrices. We hypothesized that elastic modulus and pore size govern cancer cell invasion in three-dimensional collagen matrices. In fact, invasiveness of three breast cancer cell types is altered due to matrix-type and concentration indicating that these two factors are crucial for cellular invasiveness. Our findings revealed that local matrix scaffold inhomogeneity is another crucial parameter to explain differences in cell migration, which not solely depended on pore size and stiffness of the collagen matrices. With these three distinct biophysical parameters, characterizing structure and mechanics of the studied collagen matrices, we were able to explain differences in the invasion behavior of the studied cancer cell lines in dependence of the used collagen model.

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