Texte remanié de: Diss.--Kassel--Univ. Kassel, 1994. / Bibliogr. p. 207-234.

Reproduction de : Thèse de doctorat : Sciences économiques : Lyon 2 : 2005. / Titre provenant de l'écran-titre. Bibliogr.

Evaluation Problem: The Western Cape Provincial Government faces a public problem of declining service levels with respect of public bus transport services. Stemming from the public problem is the management problem of modelling choice behaviour of commuter stated choices for utility maximisation and therefore as a means of optimising the allocation of the Public Transport Operating Grant (PTOG) expenditure. Historically, differing perceptions amongst travellers, and the difficulties in quantifying these attributes, mean that they are rarely included (directly) within the modelling and appraisal process, or the associated utility computation (Crockett, Sinclair and Whelan. 2008:11). A combination of policies which would ensure that the discrete choices of commuters for an improved bus service are considered in a modal shift from the Golden Arrow Bus Services (Pty) Ltd (GABS) bus service to the MyCiTi Integrated Rapid Transit (IRT) service is required to be produced from this evaluation. Evaluation Approach: The evaluation brings together data and analytical information on a broader, more inclusive, societal model of the public transport service in Cape Town. It seeks to: - identify the value aspects of the public bus transport infrastructure and services, - identify and model choice behaviour of GABS bus service users, - generate preference valuations for public transport service attributes and - determine the effect of service attributes on modal choice namely GABS and a hypothetical MyCiTi service area. A discrete choice experiment models the stated choices of respondents who were made to choose between various combinations of service levels during the morning and afternoon peak commuting times. The commuters' willingness to pay for a switch to a new MyCiTi IRT-type service from their current choice of an existing GABS bus service is estimated. The choice data is collected by means of an on-board bus survey along three particular routes in Table View, a West Coast Region in the City of Cape Town, South Africa and where the new MyCiTi service is being introduced. The analyses will show which service attributes are significant in commuter mode choice behaviour, such as changes travel time, fare prices and other significant service attributes, as well as which level of service would maximise utility for the target population. Major Evaluative Conclusions: The evaluation found that the DCE choice modelling approach used was unfamiliar to the respondents and would most likely not have been completely understood. Although the factorial approach to designing the experiment could identify an exhaustive list of value aspects to choose from, the need to adopt a fractional factorial in the final design does necessitate further experimentation to produce a more comprehensive choice model, inclusive of more service attributes and with the discrete choice models corroborated with revealed preference data. Seat availability was by far the most significant choice determinant and the lack thereof would be a serious deterrent to a modal shift to using the new MyCiTi service. The number of transfers during the trip and the distance of the bus stop from home were also significant choice determinants. The choice models indicated that the female commuters particularly, were willing to pay for the new MyCiTi bus-type service. In the absence of suitable seating capacity, a reduced travel time would be required to reduce the standing times and make the MyCiTi service an attractive option. The analysis produced inconclusive data for ridership predictions, although it can generally be said that provided sufficient seating, the GABS bus users will be willing to switch modes, as there is no indication in the data to suggest otherwise. Considering the preferences expressed for the service attributes, a hypothetical service can be proposed, with a service mix of R9.00 per trip, that would take 45 minutes and that offered the commuter a seat for the journey. The first bus stop would be no more than two kilometres away and the journey would consist of no more than one transfer to reach the final destination.

The implementation of new public transport networks, such as the Gautrain, present new responsibilities and opportunities for urban development. Mega projects like these are constructed for various economical, social and political reasons. These underlying orders beg a necessary question when defining the architectural program required for the integration of the stations and there relative contexts. Integration is a key narrative for the exploration and enquiry of this thesis. The new Gautrain system should connect with existing and future transport systems, social systems and other contextual realities. Another question raised throughout the theoretical enquiry of this thesis is; to what extent does this connection and integration occur at the recently completed Gautrain stations? The idea of creating ‘Gateways’ into a city, rather than mere station ‘posts’ is explored as an architectural narrative. These ‘Gateways’ become the introductory point for commuters and an opportunity to create an experiential dimension relating to ‘the image of a city’ and its ‘zeitgeist’. Pretoria Station was chosen due the many layers of integration intrinsic to the site. This opportunity is available due to the existence of neo‐classical buildings within the immediate and macro context. Here the application of a contemporary, 21st century piece may create a representation of the progression of architectural and sociological thinking, relating to city building and transportation. This site also offers opportunities for exploring the integration of existing and future transport networks due to the existence of several of transport modes. Theories of city building and ‘placemaking’ are explored as a requirement borne out of the neglect for this site as it has developed through the modern era.

Thèse de doctorat : Sciences économiques. Economie des transports : Lyon 2 : 2007. / Titre provenant de l'écran-titre. Bibliogr.

Thesis (Ph. D.)--College of William and Mary. / Typescript (photocopy). Vita. Includes bibliographical references.

No description available.

No description available.

Thesis (M.Sc.) (Operations Research) --University of Limpopo, 2009. / This study is focused on the scheduling of minibus (taxi) transport between the City of Polokwane and Mankweng Township in the Limpopo Province of South Africa. New formulations of integer programming for taxi timetabling problems were presented. The problem is modeled as a single link transit. Hard and soft constraints have been identified. The main objective of the study is to design the best schedule that minimizes the waiting time of passengers and provides better service to the public for taxi transport on the aforementioned link. In this study the proposed solution methods managed to produce a timetable with a non-conflicting set of taxis and no consecutive assignment of one taxi to the trips within a duration time (total time traveled on a return trip between two locations). Local search algorithms such as the Genetic Algorithm are used in the research, mainly due to its flexibility and power to produce the best solution to the timetabling problems. The algorithm starts with a population of a feasible search space. Two operators: mutations and crossovers, were designed in such a way that they do not produce infeasible offspring. / National Research Foundation (NRF) in conjunction with the University of Limpopo.

acase@tulane.edu / The sodium-dicarboxylate co-transporter NaDC1/SLC13A2, located at the apical membrane of the proximal tubule, reabsorbs Krebs cycle intermediates from the glomerular filtrate and is thought to be responsible for the bulk of citrate transport in the nephron. Previous studies in our lab have shown that NaDC1 is not calcium-sensitive and that transport of citrate and succinate in opossum kidney (OK) proximal tubule cells is calcium-sensitive. When apical extracellular calcium is lowered apical citrate transport increases significantly in OK cells. In this study we demonstrate that stimulating the Calcium-Sensing Receptor (CaSR) by addition of spermine in normal and low extracellular calcium results in inhibition of succinate transport indicating that the CaSR plays a role in calcium-sensitive dicarboxylate transport regulation. Thapsigargin, commonly used to increase intracellular calcium, also inhibited succinate transport in normal and low extracellular calcium. This indicates that the CaSR signals through the guanine nucleotide binding protein Gq. In addition to increased intracellular calcium, Gq signaling also activates Protein Kinase C (PKC). The PKC activator, Phorbol 12-Myristate 13-Acetate (PMA), inhibited dicarboxylate transport in low extracellular calcium only indicating that PKC regulates calcium-sensitive transport specifically. Also investigated were the potential roles of the Gi and Gs pathways. Gi and Gs inhibit and activate adenylate cyclase respectively. Inhibiting Gi with Pertussis Toxin and treating cells with 8-Br-cAMP had no effect on transport indicating that neither Gi nor Gs regulate dicarboxylate transport. Inhibiting adenylate cyclase with MDL 12,330A decreased dicarboxylate transport in normal and low extracellular calcium. However, 8-Br-cAMP did not reverse these effects indicating that MDL 12,330A is inhibiting transport in some way other than Gi signaling. To determine that in OK cells if ligand biased signaling of the CaSR favors Gq at the expense of Gi and Gs, ELISA assays were used to measure intracellular cAMP concentration. We found that calcium and spermine do not change intracellular levels of cAMP. Thus, our studies on Gq, Gi and Gs signaling reveal that there is ligand biased signaling of the CaSR in favor of the Gq pathway and that dicarboxylate transport is regulated by the CaSR → Gq → PKC pathway. / 1 / Ryan Walker