Notre compréhension de la mobilité criminelle repose presque exclusivement sur des études sur le journey-to-crime qui portent sur l'analyse des distances parcourues par les délinquants entre leur domicile et le lieu de leurs crimes. Dans cette thèse, nous nous demandons d'abord si la pertinence théorique et la validité méthodologique sous-jacente à la mesure de journey-to-crime ont été suffisamment démontrées pour justifier son influence dominante dans le domaine de la criminologie environnementale. Sur la base d'une analyse critique des recherches sur le journey-to-crime, nous soutenons que si l'intérêt pour la mesure est compréhensible, il existe de meilleures façons de mesurer la mobilité criminelle. Nous démontrons que certains postulats implicites qui la sous-tendent sont trompeurs et que de nombreux biais méthodologiques limitent son utilité. Nous suggérons que pour mieux comprendre la mobilité criminelle, le journey-to-crime devrait devenir complémentaire à de nouvelles mesures plus raffinées. Des implications pour les études futures sont proposées. Nous quantifions ensuite de manière empirique les différents biais méthodologiques de la mesure de journey-to-crime en examinant dans quelle mesure ceux-ci affectent sa capacité à estimer le « véritable » trajet effectué par les délinquants lors de la perpétration de leurs crimes. À l'aide de données policières, d'entrevues et de technologies numériques de cartographie, l'itinéraire détaillé emprunté par 98 délinquants lors de 449 crimes de vol est reconstitué afin de tester certaines des hypothèses qui sous-tendent la mesure de journey-to-crime. Les données policières utilisées pour calculer les distances résidence-crime se sont révélées être suffisamment fiables au niveau du lieu du crime, mais peu fiables pour ce qui est du lieu de résidence du délinquant. Plusieurs raisons sont fournies pour expliquer pourquoi les policiers ont de la difficulté à identifier correctement où un délinquant réside réellement le jour d'un crime donné. La résidence des délinquants s'est distinguée comme un endroit important de leur parcours criminel, mais le trajet effectivement emprunté par ces derniers s'est avéré beaucoup plus complexe que l'itinéraire résidence-crime-résidence présumé par la mesure de journey-to-crime. Malgré ses nombreuses lacunes, nos résultats ont démontré que cette mesure pouvait quand même être considérée comme une estimation valide et utile de la distance totale réellement parcourue lors d'un crime par les auteurs de vols qualifiés et d'autres vols, mais pas par les auteurs de cambriolages et de vols de véhicule à moteur. Les implications pour la recherche sur la mobilité criminelle et les études futures sont abordées. Nous investiguons finalement le nomadisme criminel, soit la propension d'un individu à s'engager dans des déplacements interurbains continus ou intermittents comme moyen de faire face aux conséquences de son mode de vie criminel (p. ex., stigmatisation, pauvreté, désorganisation, etc.) et/ou comme stratégie d'adaptation à la réalité d'être un « criminel de carrière ». L'itinéraire des crimes commis au Canada pendant la carrière criminelle de 448 hommes reconnus coupables d'infractions sexuelles a été reconstitué grâce à des entrevues individuelles et à l'analyse détaillée de casiers judiciaires. Cinq composantes distinctes du nomadisme criminel (c.-à-d., nombre de trajets, nombre de points nodaux, longueur des routes, étendue géographique de la criminalité et superficie de la zone d'activité mesospatiale), inspirées de la théorie des patrons criminels (crime pattern theory), sont suggérées et analysées. Les résultats montrent que le nomadisme criminel est davantage la réalité de gens de race blanche, jeunes et éduqués, qui ont une carrière criminelle prolifique entrecoupée de longues peines d'incarcération. Les délinquants nomades n'errent pas au hasard, mais semblent plutôt chercher des opportunités et un retour à une certaine forme d'anonymat. Les variables relatives aux infractions sexuelles n'ont pas apporté une contribution significative aux modèles de prédiction, ce qui donne à penser que le nomadisme criminel est davantage un phénomène criminel général que spécifique aux infractions sexuelles. Nos résultats suggèrent qu'une carrière criminelle prolifique est généralement associée à un mode de vie nomade et géographiquement dispersé. Les implications pour les politiques publiques et les études futures sont abordées. / Our collective understanding of criminal mobility relies almost exclusively on journey-to-crime research, which focuses on the distances traveled by offenders from their homes to the location of their crimes. In this thesis, we first ask whether the theoretical relevance and the methodological validity underlying the journey-to-crime measurement are sufficient for it to continue to be a leading influence in the field of environmental criminology. Based on a critical review of the foundations of journey-to-crime research, we argue that while the interest in the journey-to-crime measurement is understandable, there are better ways to assess criminal mobility. Some likely misleading implicit presuppositions and methodological biases are identified, and the manner in which they affect our comprehension of criminal mobility is discussed. We suggest that a better understanding of criminal mobility would come from complementing journey-to-crime with new, more refined, measures. Implications for future studies are proposed. We then empirically quantify the methodological biases of the journey-to-crime measurement, by investigating the extent to which they affect its ability to estimate the itineraries offenders actually travel during the perpetration of their crimes. With the support of police-arrest records, interviews, and web-mapping technologies, the detailed route taken by 98 offenders during 449 theft-related crimes are reconstructed in order to test some of the key assumptions underlying journey-to-crime research. Police data used to compute home-crime distances have been found to provide satisfactorily accurate crime-location addresses, but poorly accurate offender home-addresses. Several explanations of why the police have problems correctly identifying where an offender is truly residing on the day of a given crime are presented. Even if the offender's residence was the most important node in their crime journey, the actual travel undertaken by offenders was much more complex than the home-crime-home itinerary assumed by the journey-to-crime measurement. Despite its numerous drawbacks, the traditional journey-to-crime measure is still a valid and useful proxy for the total distance actually traveled by offenders in robbery and “other theft”, but not in burglary and motor-vehicle theft. Implications for criminal mobility research and future studies are discussed. We finally investigate criminal nomadism ― an individual’s propensity to engage in continuous or intermittent interurban travel as a way to cope with the consequences of their criminal lifestyle (e.g., stigma, poverty, disorganization, etc.) and/or as a strategy to adapt to the reality of being a “career criminal.” The criminal-career itinerary across Canada of 448 men convicted of sex offenses was reconstructed through individual interviews and analysis of detailed criminal records. Five distinct components of criminal nomadism (i.e., trips, nodes, paths, range, and mesolevel activity space), inspired by crime pattern theory, are suggested and analyzed. Results show that criminal nomadism is the reality of young and educated Whites who have a prolific criminal career interspersed with long incarceration sentences. Nomadic offenders did not wander freely and randomly, but rather seemed to be looking for opportunities and privacy. Sex-offending variables did not make a significant contribution to predictions, suggesting that criminal nomadism is more a general offending phenomenon than something specific to sex offending. This provides supporting evidence for the hypothesis that an extensive criminal career is generally associated with a geographically scattered and nomadic lifestyle. Implications for public policies and future studies are discussed.

This is a comparative study of the spatial patterns of peasant crop farming in Chibombo District between the 1980s and the 1990s. The study lists and discusses the agricultural support system, communication infrastructure and the crop production and patterns of the 1980s within the environment of centralised planning and then compares these to the structures and patterns of the 1990s in an atmosphere of economic liberalisation. This comparison in crop production, cropping patterns, institutional support systems and the communication infrastructure in five sampled farming wards of Chibombo District, leads to the conclusion that there is a marked change in the structures and patterns of the 1990s from those of the 1980s. Thus, in Chibombo District, the state of the communication infrastructure in the 1990s is generally poorer than the communication infrastructure of the 1980s, the agricultural support system of the 1990s is largely privately owned and found in fewer farming areas while the agricultural support system of the 1980s was state controlled and more widely spread, and crop patterns in some farming wards are different in the 1990s from those of the 1980s. In the 1990s, crop production in farming wards with a supportive environment has increased than it was in the 1980s but decreased in those where a conducive environment lacks. In this line, the study makes several recommendations for consideration on how to mitigate the problems that the peasant farmers are facing or how to enhance the positive changes that have occurred in Chibombo District. / Geography / M.A. (Geography)

This is a comparative study of the spatial patterns of peasant crop farming in Chibombo District between the 1980s and the 1990s. The study lists and discusses the agricultural support system, communication infrastructure and the crop production and patterns of the 1980s within the environment of centralised planning and then compares these to the structures and patterns of the 1990s in an atmosphere of economic liberalisation. This comparison in crop production, cropping patterns, institutional support systems and the communication infrastructure in five sampled farming wards of Chibombo District, leads to the conclusion that there is a marked change in the structures and patterns of the 1990s from those of the 1980s. Thus, in Chibombo District, the state of the communication infrastructure in the 1990s is generally poorer than the communication infrastructure of the 1980s, the agricultural support system of the 1990s is largely privately owned and found in fewer farming areas while the agricultural support system of the 1980s was state controlled and more widely spread, and crop patterns in some farming wards are different in the 1990s from those of the 1980s. In the 1990s, crop production in farming wards with a supportive environment has increased than it was in the 1980s but decreased in those where a conducive environment lacks. In this line, the study makes several recommendations for consideration on how to mitigate the problems that the peasant farmers are facing or how to enhance the positive changes that have occurred in Chibombo District. / Geography / M.A. (Geography)

In recent decades, it was shown that belowground competition for some plants may take form of the tragedy of the commons (TOC). In these plants, the competing neighbours invest more in root systems than would be appropriate for optimal nutrient uptake for the group and also more than they do when grown alone. However, there is also strong evidence that other species do not follow TOC, and tailor their root system to best nutrient exploitation irrespectively of competitor presence. The root investment strategy of these plants should correspond to the ideal free distribution (IFD). In my thesis I focus on two aspects:  I use game theoretical models to explore, whether those strategies can coexist within species and also whether different species can coexist if they have different strategy. From this model I draw predictions, which I test by meta-analysis.  Using Agrostis stolonifera as a model, I test assumptions on nutrient and neighbour perception, which underlie TOC and IFD models. I show that according to mathematical models, those two strategies can coexist in different species in a community, but cannot coexist within a species. Within a species, the TOC strategy should always dominate, once it appears. This can be extrapolated to macroevolutionary scale - once TOC occurs in certain clade, it should...

Eine große Herausforderung für Verkehrsmodelle stellt die korrekte Abbildung der Entscheidungsmuster bei der Zielwahl dar. Diese bestimmt die räumlichen Strukturen der Nachfrage und steht in engem Zusammenhang mit zentralen Ergebnissen der Nachfragemodellierung. Rund ein Drittel der Alltagswege in Deutschland sind Einkaufs- und Erledigungwege. Zahlreiche Arbeiten zeigen die Bedeutung von habitualisierten Verhaltensmustern bei der Wahl eines Einkaufsortes. Die Motive der Geschäftswahl gelten als sehr vielfältig. Besondere Bedeutung wird zudem den Primäraktivitätenorten zugeschrieben. Gleichwohl erfolgt die Abbildung der Zielwahl in der Nachfragemodellierung zumeist sehr vereinfachend. Gewöhnlich wird von einem Versorgungseinkauf mit der Geschäftsgröße und der Anreisezeit ausgegangen. Diese Arbeit zeigt anhand empirischer Auswertungen Möglichkeiten einer verhaltensorientierten Abbildung der Einkaufszielwahl in mikroskopischen Personenverkehrsmodellen auf. Im Fokus stehen die Variabilität der Geschäftswahl, die ausschlaggebenden Motive sowie die räumlichen Bezugspunkte der Suche. Am Beispiel des Erwerbs von Nahrungs- und Genussmitteln, von Textilien sowie von Unterhaltungselektronik werden Unterschiede zwischen Einkaufswaren verschiedener Fristigkeit, aber auch zwischen verschiedenen Personengruppen herausgearbeitet. Simulationsrechnungen mit dem Nachfragemodell TAPAS zeigen, dass eine Differenzierung der Einkaufsart sowie die Nutzung eines motivgestützen Erreichbarkeitsmaßes die Modellierungsergebnisse stark verbessern. Die Arbeit stellt erweiterte Indikatoren für eine Berücksichtigung der räumlichen Bezugspunkte bei der Beurteilung der Modellierungsergebnisse bereit. Auch stehen mit den Analysen der Aktivitätenräume, der Umwegfaktoren, der Lage der Einkaufsorte sowie der kumulierten Reiseweiten Informationen zur Verfügung, die generell für die Definition adäquater Suchräume und Bezugspunkte für die Modellierung städtischer Untersuchungsgebiete genutzt werden können. / A major challenge in travel demand modelling is the correct representation of decision patterns underlying the choice of destinations. This choice determines the spatial structures of demand and is closely related to central modelling results. Around one third of everyday trips in Germany are for shopping and errands. Numerous studies show the importance of habitualised behavioral patterns when choosing a shopping location. The motives for choosing a shop are considered to be very diverse. Particular importance is attributed to primary activity locations. Nevertheless, the representation of the target choice in demand modelling is usually very simplified. Usually, a supply purchase is implicitly assumed, with the size of the shop and travel time from the previous location being the most important choice criteria. Using empirical analyses, this dissertation shows possibilities for a behavior-oriented depiction of shopping location choice in microscopic passenger transport models. These are discussed in terms of their usability for modeling. The analyses focus on the variability of destinations, the decisive motives and the spatial reference points of the location search. Using the example of the purchase of food and beverages, textiles and consumer electronics, differences between shopping goods of different periodicity and also different groups of people are presented. Simulation calculations with the demand model TAPAS show that a differentiation of the type of purchase and the use of a motive-based accessibility measure greatly improves the modelling results. The dissertation provides extended indicators for a consideration of spatial reference points in the evaluation of the modelling results. Furthermore, the analyses of activity areas, diversion factors, the location of shopping locations and cumulative travel distances provide information that can be generally used to define adequate search areas and reference points for the modelling of urban study areas.Einkaufsverhalten