EFFECTS OF MODULATED LDLs ON THE RELEASE OF ENDOTHELIN-1AND PROSTACYCLIN BY ENDOTHELIAL CELLS IN CULTURE

Epidemiological studies have demonstratedthat hyperlipidemia and smoking are synergisticfactors for atherogenesis and its complications['j,but the mechanism behind is not fully clarified. En-' dothelium--derived vasoconstrictors, in contrast toendothelium-derived vasodilators lead to smoothmuscle cell (SMC) contraction and support SMCproliferation which might be involved in the originand the development of atherosclerosis[2.3J, Lipid-soluble smoke particels,which contain high concen-trations…     

Trip chaining as a barrier to the propensity to use public transport

Trip chaining is a growing phenomenon in travel and activity behaviour. Individuals increasingly seek out opportunities to minimise the amount of travel required as part of activity fulfilment, given the competing demands on time budgets and their valuation of travel time savings. This search for ways of fulfilling (more) activities with less travel input has produced a number of responses, one of which is trip chaining. A particularly important policy implication of trip chaining is the potential barrier it creates in attracting car users to switch to public transport. This paper seeks to improve our understanding of trip chaining as a barrier to public transport use. A series of discrete choice models are estimated to identify the role that socio-economic and demographic characteristics of households have on the propensity to undertake trip chains of varying degrees of simplicity/complexity that involve use of the car or public transport with an embedded commuting or non-commuting primary purpose. Multinomial logit, nested logit and random parameter logit models are developed and contrasted to establish the gains in relaxing the strict conditions of the multinomial logit model.     

Assessment of large transport infrastructure projects: The CBA-DK model

This paper presents a newly developed decision support model to assess transport infrastructure projects: CBA-DK. The model combines use of conventional cost–benefit analysis to produce aggregated single point estimates, with quantitative risk analysis using Monte Carlo simulation to produce interval results. The embedded uncertainties within traditional CBA such as ex-ante based investment costs and travel time savings are of particular concern. The paper investigates these two impacts in terms of the Optimism Bias principle which is used to take account of the underestimation of construction costs and the overestimation of travel time savings. The CBA-DK methodological approach has been used to apply suitable probability distribution functions on the uncertain parameters, thus resulting in feasibility risk assessment moving from point to interval results. The proposed assessment model makes use of both deterministic and stochastic based information. Decision support as illustrated in this paper aims to provide assistance in the development and ultimately the choice of action, while accounting for the uncertainties surrounding transport appraisal schemes. The modelling framework is illustrated by the use of a case study appraising airport and runway alternatives in the capital of Greenland – Nuuk. The case study has been conducted in cooperation with the Home Rule Authorities of Greenland.     

Toll product preferences and implications for alternative payment options and going cashless

There has been a great deal of research on deriving estimates of the value of travel time savings (VTTS) as a way of converting travel time benefits of toll roads relative to free routes into monetary units, the major user benefit in the development of forecasts of traffic and hence revenue streams. By contrast there has been almost no consideration given to identifying the role that various tollroad products play in establishing preferences for toll routes over non-tolled routes. Increasingly tollroads give users the option to pay by cash at a toll booth, by electronic tolling or by a pre- or post-paid debit and credit account system involving vehicle identification. The efficiency gained by electronic tolling for both the users and the operator have resulted in moves in many jurisdictions to eliminate cash collection entirely (or not introduce it when introducing a new tolled road facility), and to introduce a range of pre- and post-payment options. This has been accompanied by a growing move to distance-based charging in some contexts which is more cumbersome to structure with a cash option. This paper investigates current and potential travellers’ preferences for a range of toll products and how much individual’s are willing to pay for very specific toll products. Data from a stated choice experiment is used in a mixed logit model to establish the role that toll products play in the context of offered times and costs of alternative routes, in choosing between alternative ways of paying for the use of tolled routes.

A KBS application for market research advice in transport

This paper presents some results of a knowledge based system (KBS) development applied to market research (MR) issues in transport. This application represents a rule production approach to decisions associated with the definition of appropriate survey procedures for various operation‐management problems in a transport enterprise or agency. The basic idea is to provide an aid for the user (manager, student or practitioner), who is concerned with MR, but is not very familiar with this field or has some concerns over data‐gathering and the use of that information. It focuses on specific applications in the transport environment and gives the user some support in maintaining greater consistency in his (her) decisions.

The objective of this paper is to describe the system structure, to point out some important aspects and problems arising during its development and also to make some comments with respect to the further development of this and similar systems.     

Delivering Value for Money to Government through Efficient and Effective Public Transit Service Continuity: Some Thoughts

Abstract

This paper documents some thoughts on the reform agenda in public transit that is occurring throughout the world. The specific focus is on a growing commitment to competitive regulation through competitive tendering, and the efforts by a few governments (notably in Australia) to take control of the tangible assets used by private operators as a mechanism to exercise the opportunity, if so taken, to put services out to competitive tender. The paper reviews the theoretical arguments and empirical evidence on contracting regimes and asset ownership, and the role that government and the operator might play in a setting in which building trusting and collaborative partnerships has merit in delivering services that are in the main funded from the public purse.     

Transport policy for an ageing population

Mobility declines with increasing age, reflecting the onset of physical or mental infirmity, affordability of travel for those on retirement incomes, and the mal-design of the transport infrastructure and operational arrangements. With the prospect of a rapidly ageing population, it is important to address measures to promote mobility if the quality of life of older people is to be sustained. In the UK, pensioners on low incomes, who could be hindered in their travel by the cost of fares on public transport, benefit from the general availability of half price (or better) concessionary fares for local travel. A variety of measures are in place to counter the effects of age-associated disabilities that hinder mobility, including low floor buses, subsidised taxis and community transport schemes. The Disability Discrimination Act is ensuring that public services vehicles are accessible to older people with disabilities. The motor car is of increasing importance in later life, particularly for those with disabilities, and a variety of design and technological approaches are being brought to bear to maintain the mobility of older people. These various efforts undoubtedly enhance the mobility of older people. However, beyond that broad conclusion it is hard to make evidencebased judgements. There is therefore a pressing need to develop methods to evaluate developments in policy and practice.     

Limitations of transport policy

There is an implication in the notion of 'transport policy' that substantial improvements could be made to the transport system given sufficient ingenuity, investment and good will. This paper argues that such policy aspirations cannot cope with the desire for ever-increasing mobility, a deep and powerful force in modern society. In densely populated countries there is no possibility of meeting the demand for unconstrained movement through construction of additional transport infrastructure, since new and longer journeys would quickly fill the extra capacity until the congestion equilibrium is re-established. What limits mobility in practice is the time individuals have available for travel, time which is equitably distributed. Transport plans need to acknowledge this time constraint as fundamental, and accordingly be realistically modest about what is achievable. It is an illusion that the transport system could be substantially more efficient whilst remaining equitable.     

Shift of reference point and implications on behavioral reaction to gains and losses

It is widely recognized that individual decision-making is subject to the evaluation of gains and losses around a reference point. The estimation of discrete choice models increasingly use data from stated choice experiments which are pivoted around a reference alternative. However, to date, the specification of a reference alternative in transport studies has been fixed, whereas it is common to observe individuals adjusting their preferences according to a change in their reference point. This paper focuses on individual reactions, in a freight choice context, to a negative change in the reference alternative values, identifying the behavioural implications in terms of loss aversion and diminishing sensitivity. The results show a significant adjustment in the valuation of gains and losses around a shifted reference alternative. In particular, we find an average increase in loss aversion for cost and time attributes, and a substantial decrease for punctuality. These findings are translated to significant differences in the willingness to pay and willingness to accept measures, providing supporting evidence of respondents’ behavioural reaction.