104 research outputs found

    Interactions In Space For Archaeological Models

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    In this article we examine a variety of quantitative models for describing archaeological networks, with particular emphasis on the maritime networks of the Aegean Middle Bronze Age. In particular, we discriminate between those gravitational networks that are most likely (maximum entropy) and most efficient (best cost/benefit outcomes).Comment: 21 pages, 6 figures, 2 tables. Contribution to special issue of Advances in Complex Systems from the conference `Cultural Evolution in Spatially Structured Populations', UCL, London, September 2010. To appear in Advances in Complex System

    Volatile Decision Dynamics: Experiments, Stochastic Description, Intermittency Control, and Traffic Optimization

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    The coordinated and efficient distribution of limited resources by individual decisions is a fundamental, unsolved problem. When individuals compete for road capacities, time, space, money, goods, etc., they normally make decisions based on aggregate rather than complete information, such as TV news or stock market indices. In related experiments, we have observed a volatile decision dynamics and far-from-optimal payoff distributions. We have also identified ways of information presentation that can considerably improve the overall performance of the system. In order to determine optimal strategies of decision guidance by means of user-specific recommendations, a stochastic behavioural description is developed. These strategies manage to increase the adaptibility to changing conditions and to reduce the deviation from the time-dependent user equilibrium, thereby enhancing the average and individual payoffs. Hence, our guidance strategies can increase the performance of all users by reducing overreaction and stabilizing the decision dynamics. These results are highly significant for predicting decision behaviour, for reaching optimal behavioural distributions by decision support systems, and for information service providers. One of the promising fields of application is traffic optimization.Comment: For related work see http://www.helbing.or

    Modelling gender perception of quality in interurban bus services

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    This paper models how women and men perceive the quality of interurban bus services and proposes a new methodology for detecting the highest priority service variables to act on. Service quality perception was modelled using both ordered logit and ordered probit models using data from revealed preference surveys. The methodology for detecting different priority levels uses the graphic representation of the relationships between influence in the model and average evaluation by users. The modification of certain variables increases the knowledge of how woman evaluate quality in bus services to help promote the use of interurban public transport. Statistical analysis of the data provides some conclusions such as: the proportion of users increases as age decreases for both men and women; and women seem to make shorter and more frequent trips than men. The best model for this data set was ordered logit. As expected, the most relevant variable is the relationship between quality and price. Other important variables are the condition of the bus and the frequency of service

    Assessment of the Degree of Willingness to Change from Motorized Travel Modes to Walking or Cycling

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    This paper presents an analysis of the degree of willingness to change from motorized travel modes to walking or cycling. The aim of the analysis is to reduce uncertainty between stated willingness to change and real shifts from car or transit to nonmotorized transportation modes. Data were collected in the city of Valencia, Spain, through a novel data collection effort based on multiple survey methods. Respondents traveling by car or transit were asked about their willingness to change to walking or cycling under the implementation of improvement measures to be selected. Then a hypothetical scenario was presented to respondents who stated a willingness to change; in the scenario, the previously selected measures were implemented and respondents were supposed to be cycling or walking. In addition, the costs of their usual travel mode were gradually reduced until they gave up cycling or walking. Those who decided to keep on walking or cycling were assumed to have a strong willingness to change. A statistical analysis performed with Heckman's sample selection model permitted identification of demographic, socioeconomic, and travel-related factors influencing the degree of willingness to change. Results revealed that car users presented a stronger willingness to switch to walking or cycling than transit users. In addition, older respondents showed a stronger willingness to change to both walking and cycling. Work- and school-related journeys were less associated with walking than noncommuting journeys, but they were more related to cycling. Policy implications of the results are highlighted.Ferrer, S.; Ruiz SĂĄnchez, T. (2013). Assessment of the Degree of Willingness to Change from Motorized Travel Modes to Walking or Cycling. Transportation Research Record. (2382):112-120. doi:10.3141/2382-13S112120238

    High-Speed Rail Versus Air Transportation: Case Study of Madrid–Barcelona, Spain.

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    Travel time savings, better quality of the supplied services, greater comfort for the users, and improved accessibility are the main factors of success of High Speed Rail(HSR)links. This paper presents the results from a revealed and stated preference survey conducted to both HSR and air transport users in the Madrid Barcelona corridor. The data gathered from the stated preference survey was used to calibrate a modal choice model aiming at explaining competition between HSR and air transportation in the corridor. From the model, the authors obtain that prices and service frequency are the most important variables to compete with the other mode. In addition, they found that check-in and security controls at the airport are a crucial variable for the users in their modal choice. Other policies, such as the improvement of parking facilities at the train stations, play a secondary role

    Demand for environmentally friendly vehicles: A review and new evidence

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    Although the need for more environmentally friendly vehicles was recognized some decades ago, this new market has not yet established itself. Consumer behavior needs to be studied to ascertain when people will decide to purchase hybrid or electric vehicles rather than conventional ones. An in-depth review of the state-of-the-art has identified existing deficiencies and these are addressed in this paper, proposing a new approach that is applied to the case of Santander in Spain. Emphasis is placed on the role of citizens in researching the local market and their requirements with respect to such vehicles; our model assumes variability in user preferences, an utmost requirement as concluded from the literature review. Results suggest that the highest demand for cleaner vehicles would be achieved in two ways: firstly, by penalizing conventional vehicles in terms of costs/km; secondly, by providing incentives directed at lowering the purchasing price of hybrid and electric vehicles. Finally, as demand becomes more elastic, the preferred strategy should initially focus on hybrid vehicles

    Outcomes from elective colorectal cancer surgery during the SARS-CoV-2 pandemic

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    This study aimed to describe the change in surgical practice and the impact of SARS-CoV-2 on mortality after surgical resection of colorectal cancer during the initial phases of the SARS-CoV-2 pandemic
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