Modeling commuter preferences for the proposed bus rapid transit in Dar-es-Salaam

The paper analyzes individual commuter preferences towards the proposed bus rapid transit (BRT) system in Dar-es-Salaam, Tanzania. The objective of the survey was to identify how commuters perceive and value the proposed BRT service quality attributes. A stated preference survey of potential users of the proposed BRT was administered to 684 commuters who traveled to the central business district (CBD) on a regular basis. To this end, a special pictorial score card was developed that was suited for the local context and needed to capture the preferences of the commuter respondents. The BRT attributes considered for study are travel time, travel fare, and comfort. The stated choice data were analyzed using a binary logit model. The findings reveal, in order of importance, that comfort is the most valued attribute compared to travel time and travel fare, respectively

Key events and their effects on cycling behaviour in Dar-es-Salaam : abstract + powerpoint

The paper explores key events and investigates their effects on cycling behaviour in the city of Dar-es-Salaam, Tanzania. The objective of the study is to identify specific key events during a person’s life course with a significant effect on change of travel behaviour towards cycling in relation to stage of change. Stage of change is a key construct of the transtheoretical model of behaviour change that defines behavioural readiness (intentions and actions) into six distinct categories (i.e. pre-contemplation, contemplation, prepared for action, action, maintenance, and relapse). By using a binary logistic regression model, it was possible to identify the key events that influenced change of travel behaviour among 450 daily commuters in different stages of change of cycling behaviour. Model results have shown that income generation, poor daladala (public transport) service, and harsh behaviour of daladala operators have a significant impact on changing to maintenance stage. After marriage, after child birth, past incidence of car accident on bicycle, feel shame on bicycle, fear of losing virginity among girls and shifting from small towns to Dar-es-Salaam where cars are the common mode of travel, have a significant impact on cycling especially moving from maintenance to relapse stage of cycling behaviour

A Methodology to Engineer and Validate Dynamic Multi-level Multi-agent Based Simulations

This article proposes a methodology to model and simulate complex systems, based on IRM4MLS, a generic agent-based meta-model able to deal with multi-level systems. This methodology permits the engineering of dynamic multi-level agent-based models, to represent complex systems over several scales and domains of interest. Its goal is to simulate a phenomenon using dynamically the lightest representation to save computer resources without loss of information. This methodology is based on two mechanisms: (1) the activation or deactivation of agents representing different domain parts of the same phenomenon and (2) the aggregation or disaggregation of agents representing the same phenomenon at different scales.Comment: Presented at 3th International Workshop on Multi-Agent Based Simulation, Valencia, Spain, 5th June 201

Spatial variation of transit service quality preferences in Dar-es-Salaam

Commuter preferences for transit service quality are of great importance to transit service providers and regulatory agencies. The point of view of potential passengers is fundamental for evaluating transit service quality as they are envisaged to be the real consumers of the planned services and can therefore be considered the most suitable judges. A stated preference survey of daily commuters to the central business district (CBD) in the city of Dar-es-Salaam, Tanzania, was carried out to elicit preferences towards the proposed Dar Rapid Transit (DART) service. Preferences towards the proposed DART service are considered to vary based on the residential location of the potential users. These preferences are evaluated on the attributes travel time, fare and comfort. A binary logit model was applied to establish utility functions that were analysed spatially in a GIS, where a utility value was computed for each spatial unit. This paper accordingly analyses spatial variation of transit service quality preferences for the proposed DART service using geo-spatial techniques. The study uses a scenario-based approach to evaluate the effect of the proposed DART service by comparing the ‘without DART’ scenario, a case representing the existing public transport (daladala), and a ‘DART’ scenario, representing the future proposed DART system. The results indicate that the proposed DART attributes considered in the study have a significant effect on DART service quality. The results further reveal that utility values are significantly varying spatially, particularly dependent upon distance to CBD. Comfort is the most important attribute in zones up to 5 km from the CBD, travel fare is more important in zones between 5 and 15 km from the CBD, while travel time is more important in zones beyond 15 km distance from the CBD. The overall results indicate that the DART is likely to be more attractive than the existing public transport system

Dendritic Cells in Human Atherosclerosis: From Circulation to Atherosclerotic Plaques

Background. Atherosclerosis is a chronic inflammatory disease with atherosclerotic plaques containing inflammatory infiltrates predominantly consisting of monocytes/macrophages and activated T cells. More recent is the implication of dendritic cells (DCs) in the disease. Since DCs were demonstrated in human arteries in 1995, numerous studies in humans suggest a role for these professional antigen-presenting cells in atherosclerosis. Aim. This paper focuses on the observations made in blood and arteries of patients with atherosclerosis. In principal, flow cytometric analyses show that circulating myeloid (m) and plasmacytoid (p) DCs are diminished in coronary artery disease, while immunohistochemical studies describe increased intimal DC counts with evolving plaque stages. Moreover, mDCs and pDCs appear to behave differently in atherosclerosis. Yet, the origin of plaque DCs and their relationship with blood DCs are unknown. Therefore, several explanations for the observed changes are postulated. In addition, the technical challenges and discrepancies in the research field are discussed. Future. Future studies in humans, in combination with experimental animal studies will unravel mechanisms leading to altered blood and plaque DCs in atherosclerosis. As DCs are crucial for inducing but also dampening immune responses, understanding their life cycle, trafficking and function in atherosclerosis will determine potential use of DCs in antiatherogenic therapies

Cardiopulmonary Exercise Testing in Pediatrics

Aerobic fitness is an important determinant of overall health. Higher aerobic fitness has been associated with many health benefits. Because myocardial ischemia is rare in children, indications for exercise testing differ in children compared to adults. Pediatric exercise testing is imperative to unravel the physiological mechanisms of a reduced aerobic fitness and to evaluate intervention effects in children and adolescents with a chronic disease or disability. Cardiopulmonary exercise testing includes the measurement of respiratory gas exchange and is the gold standard for determining aerobic fitness, as well as for examining the integrated physiological responses to exercise in pediatric medicine. As the physiological responses to exercise change during growth and development, appropriate pediatric reference values are essential for an adequate interpretation of the cardiopulmonary exercise test