Boolean networks are coarse-grained models of the regulatory dynamics that controls the survival and proliferation of a living cell. The dynamics is time- and state-discrete. This Boolean abstraction assumes that small differences in concentration levels are irrelevant; and the binary distinction of a low or a high concentration of each biomolecule is sufficient to capture the dynamics. In this work, we briefly introduce the gene regulatory models, where with the advent of system-specific Boolean models, new conceptual questions and analytical and numerical challenges arise. In particular, the response of the system to external intervention presents a novel area of research. Thus first we investigate how to quantify a node\\\''s individual impact on dynamics in a more detailed manner than an averaging against all eligible perturbations. Since each node now represents a specific biochemical entity, it is the subject of our interest. The prediction of nodes\\\'' dynamical impacts from the model may be compared to the empirical data from biological experiments. Then we develop a hybrid model that incorporates both continuous and discrete random Boolean networks to compare the reaction of the dynamics against small as well as flip perturbations in different regimes. We show that the chaotic behaviour disappears in high sensitive Boolean ensembles with respect to continuous small fluctuations in contrast to the flipping. Finally, we discuss the role of distributing delays in stabilizing of the Boolean dynamics against noise. These studies are expected to trigger additional experiments and lead to improvement of models in gene regulatory dynamics.

The existing theoretical and empirical literature to investigate the existence of local market power is typically based on spatial competition models in the tradition of Hotelling's (1929) linear city and Salop's (1979) circular city. In models of this kind, strong assumptions are made that lead to a spatial homogeneity (symmetry) of firms in a highly stylized one-dimensional market space. However, some of these assumptions are hardly satisfied in many (retail) markets. The present thesis builds on a recent model by Chen and Riordan (2007), in which the market is characterized by a star-shaped graph with a central intersection. In an extension of Chen and Riordan, I distinguish between firms close to the center and firms in the periphery of a spatial market. This spatial heterogeneity leads to an asymmetric competition between firms. A central firm directly competes with a larger number of firms than remote firms do. The implications of the theoretical model are tested in two empirical applications to the retail gasoline market of Vienna and Austria. Using station level data on diesel prices, I estimate price reaction functions for gasoline stations in two different approaches. In the first approach the Austrian retail gasoline market is divided into numerous highly localized and delimited markets. The second approach analyzes the metropolitan area of Vienna and treats the whole market as one big network of gasoline stations, which are connected through the road network. In both approaches I apply econometric spatial autoregressive (SAR) models. The estimated parameters of the slopes of the reaction functions are used to evaluate the impact of individual gasoline stations on equilibrium market prices depending on their location within the market (network). All results obtained provide evidence for (more) central suppliers serving as a stronger reference in pricing than (rather) remote suppliers. Thus, the assumption of a symmetry in spatial competition which is usually implied by spatial competition models in theoretical and applied research, is rejected. (author's abstract)

We empirically investigate the importance of centrality (holding a central position in a spatial network) for strategic interaction in pricing for the Austrian retail gasoline market. Results from spatial autoregressive models suggest that the gasoline station located most closely to the market center - defined as the 1-median location - exerts the strongest effect on pricing decisions of other stations. We conclude that centrality influences firms' pricing behavior and further find that the importance of centrality increases with market size. (authors' abstract) / Series: Department of Economics Working Paper Series

This thesis aims to investigate to what extent the centrality of religion influences the existential aspects of an individual’s meaning-system. To do this I used a meaning-system framework and a qualitative approach in which I gathered information through a questionnaire based on the Centrality of the Religious Meaning System Scale and by conducting 8 semi-structured interviews with young adults in Uppsala, Sweden. The analysis of these interviews was implemented through an abductive method. The theoretical perspective is based on the concept Global meaning and the General attribution theory. My conclusion is that those participating in the study describe their meanings differently depending on their religious meaning-system. The thesis also shows that the religious interpretations to a large degree were actualized by situational and dispositional factors. This suggest that the religious attributions were made to meet the participants need for meaning, control, and self-esteem. Finally, the thesis indicates that the centrality of one’s religion appears to inform the religious meaning-system, as well as, functions as a dispositional factor. Thus, this thesis suggests that the centrality of one’s religion can be an influential factor in how religious meaning is constructed regarding existential questions.

Riskkapitalbranschen är en växande bransch i Sverige och både en viktig finansiär samt kunskapskälla för både nystartade företag och företag med ambition att växa sig stora och internationella. Beroende på vart i livscykeln ett företag befinner sig står de inför olika utmaningar och behöver hjälp med olika saker, en hjälp som riskkapitalbolagen kan bidra med. Studien syftar till att generera kunskap om svenska riskkapitalbolag och bidra med kunskap till den kunskapslucka vi observerat inom ämnet. Studien fokuserar på nätverksstrukturen bland de företag som svenska riskkapitalbolag har valt att investera i samt skillnaden i nätversstrukturen beroende på vart i livscykeln företagen befinner sig. Med en kvantitativ metod har vi, genom att identifiera relationerna mellan de företag som riskkapitalbolagen investerar i, kartlagt nätverken mellan de olika aktörerna. Populationen bestod av svenska riskkapitalbolag och urvalet skedde strategiskt utifrån vad olika källor ansåg vara de två största och mest framgångsrika riskkapitalbolagen i norden. Med hjälp av excel, Minitab 16 samt UCINET 6 har vi kunnat illustrera de olika nätverken samt kunnat analysera dem i form av centralitet och densitet på nätverksnivå samt jämfört de olika relationerna. Studiens resultat visar på att riskkapitalbolagen är med och löser de olika fasernas karakteristiska utmaningar med hjälp av hur de strukturerar nätverken bland de företag de väljer att investera i. Detta betyder således att nätverkets struktur är viktig för de olika företagens framgång. / This study is aiming of contributing with information about Swedish Venture Capital firms, which we have found is missing. By answering research questions like how the networks of the Venture Capital firms are structured and if the network structure has different settings depending on which phases in the life cycle the invested companies are located. We focus on the Swedish venture capital firms and their networks. The network structure is analyzed out of centrality, density and number of relationships. In UCINET 6 we were able to make illustrations of our networks and to calculate the values of our variables on network level. In the statistical program Minitab, we calculated the mean value and standard deviation for the venture capitals’ invested companies’ phases.

We highlight the importance of "centrality" for pricing. Firms characterized by a more central position in a spatial network are more powerful in terms of having a stronger impact on their competitors' prices and on equilibrium prices. These propositions are derived from a simple theoretical model and investigated empirically for the retail gasoline market of Vienna, Austria. We compute a measure of network centrality based on the locations of gasoline stations in the road network. Results from a spatial autoregressive model show that prices of gasoline stations are more strongly correlated with prices of central competitors.

La croissance explosive de la population sénégalaise a permis d’atteindre 13 millions d’habitants en 2009 contre 2 millions en 1950. La moitié de cette population, constituée largement de jeunes, vivent dans les zones urbaines comme Touba, Thiès et Saint Louis. Cet essor démographique a conduit à l’extension spatiale et la création de nouvelles centralités dans les villes sénégalaises. Il en résulte des paysages urbains et des fonctions très contrastés. Ce décalage fonctionnel et géographique a créé des besoins de mobilités très fortes.Dans les zones urbaines non planifiés et/ou éloignées des centres, les mobilités de proximité se développent par le biais de la marche à pieds et des transports hippomobiles. Alors que les déplacements menant vers les centres pour des motivations de travail, de commerce, d’études ou d’accès aux services divers se font essentiellement via les transports collectifs motorisés.De toute évidence, les relations entre transport et urbanisme sont ambivalentes. Si l’urbanisation précède le réseau de transport dans les quartiers périphériques, ailleurs, ils jouent un rôle majeur dans la structuration des espaces urbains notamment dans les centres historiques et le long des grands axes routiers.Pourtant, les transports informels opèrent en marge des règles pour satisfaire les besoins de mobilité des usagers à faible revenu. Ce qui rend ainsi éminent le rôle des pouvoirs publics dans la régulation des transports. / Senegal’s population grew in excess of 13 million people in 2009 from 2 million in 1950. The urban population growth led to the spatial extension and centralities of the cities. Half of the population, largely young, lives in urban areas like Touba, Thiès and Saint Louis. That gave a very contrasting urban landscapes and diverse urban functions. This shift has created very strong functional and geographical mobility needs. In urban unplanned areas and / or remote from centers, local mobility grew through walk and horse-drawn transport. Movements leading to the centers for reasons of work, commerce, education or access to various services abound via motorized transport.Clearly, the relationship between transport and urban planning are ambivalent. If urban development precedes the transport network in the suburbs, elsewhere, it plays a major role in the structuring of urban areas, especially in the historic centers and along major highways.Yet this informal transport is operating outside the rules, it meets the mobility needs of many low-income users. Thus, it is making prominent the role of the government to regulate the transports sector.

In this dissertation, I investigate predictors and consequences of transactive memory system (TMS) development. A transactive memory system is a shared system for encoding, storing, and recalling who knows what within a group. Groups with well-developed transactive memory systems typically perform better than groups lacking such memory systems. I study how communication enhances the development of TMS and how turnover disrupts both TMS and its relationship to group performance. More specifically, I examine how communication networks affect the amount of communication, how the structure of the communication network affects the extent to which the group members share a strong identity as a group, and how both of these factors affect a group’s TMS. I also analyze how turnover disrupts the relationship between transactive memory systems and group performance. In addition, I examine how the communication network and turnover interact to affect group performance. I analyze these effects in three laboratory studies. The controlled setting of the experimental laboratory permits me to make causal inferences about the relationship of turnover and the communication network to group outcomes. Results promise to advance theory about transactive memory systems and communication networks.

Parallèlement à la géométrisation de l'espace urbain dégageant un centre géométrique, s'est développée une vision hiérarchique de l'occupation de l'espace. Le sommet de cette hiérarchie a longtemps coïncidé avec cette centralité géométrique, qui devient alors l'espace d'identification de la ville, autrement nommé le centre-ville. Or la situation des centres-villes a beaucoup évolué aujourd'hui. Bejaia, à l'instar d'autres villes du monde, n'échappe pas au phénomène de l'éclatement du centre traditionnel suivi de l'apparition de nouvelles centralités. Notre étude vise à rechercher, dans le cadre d'une pluridisciplinarité d'approche, les niveaux de ruptures et le degré de correspondance ou d'écart entre la politique planificatrice adoptée et le potentiel socio-économique et urbanistique de la ville de Bejaia concernant ses espaces centraux. Elle cherche en particulier à dégager les polarités touristiques liées au site, au patrimoine et à la société et les prédispositions touristiques qui en résultent, et à développer leur cohérence dans la perspective d'une ouverture vers l'environnement méditerranéen. / Along with the geometrization of urban space producing a geometric center, a hierarchical vision of space occupation has been developed. The top of this hierarchy has coincided for a long time with this geometrical centrality which becomes the essential element of city's identification, known by the term of downtown or city center. It is essential to note that downtowns have significantly evolved. Like other cities all over the world, the city of Bejaia doesn't escape this phenomenal disruption of these traditional centers, followed by emergence of new centralities. In the framework of a multidisciplinary approach, our study aims to discover different levels of breaks and degree of both conformance and difference between planning policy and socio-economic potentials of Bejaia, concerning its central spaces. Essentially, it searches to identify its touristic predispositions and develop their consistence and coherence in the light of opening up to the Mediterranean area.

The study explored the relationships between role centrality, work-family culture, work-family balance and work-family conflict. Additionally, it examined the incorporation of work-family culture into border permeability as used in work-family border theory. A total of 103 participants from five organisations completed the questionnaires. Participants were employed in administrative, professional/skilled/specialist, supervisory or management positions. Data were analysed using Pearson’s Product Moment correlation and Simple Regression. Significant results were obtained between role centrality, home centrality and workfamily balance as well as work-family conflict. These were in support of Clark (2000) work-family border theory. However, work centrality produced insignificant relationships. Work-family culture produced significantly strong relationships and predictability on work-family balance and conflict. The study findings highlight a need for expansion of border theory to include work-family culture as an aspect of border permeability.