Secondary roads often suffer from diverted traffic trying to avoid congestion on major motorways. In this paper we study the traffic problems of a small town that is located parallel to a congested ...motorway and suffers from such diverted traffic (high local accident risks, local congestion and other nuisances). We assume that the motorway and the secondary road through the local town are under the jurisdiction of a different authority. A local government controls local accident risks and congestion using non-price measures such as speed bumps, traffic lights and explicit access restrictions for through traffic. A ‘federal’ government can control traffic levels on the motorway using tolls. We show the following results. First, competition between the federal and local authority leads to a Nash equilibrium where the toll is too high and there is too much traffic calming compared to the second-best social optimum. Second, if the local government uses traffic calming measures, imposing a federal toll on the main road is welfare-reducing, unless congestion on the main road is severe and accident risks and other traffic nuisances in the small town are unimportant. Third, traffic diverted from the main road to the local community gives the latter strong incentives to close the local road for through traffic, even when it is socially undesirable to do so. Fourth, if the access restriction only applies to through traffic by trucks, the conflict between federal and local authorities disappears: both will agree on restricting truck access. A numerical application using a two-link network between Leuven and Brussels (the highway and an alternative road passing through local communities) illustrates the theoretical results.
This article analyses the negotiated and contingent nature of research access and limitations in a cooperative research project in Kyrgyzstan, Central Asia. It argues that even technically and ...legally ‘free’ academic research is often subject to a number of restrictions emanating from the politicization of research at the so-called frontiers of the global political economy of academic knowledge production. This frontier status and contested nature of knowledge and research is especially marked in Kyrgyzstan, where recent revolutions and social conflict have created a tense climate amidst authorities’ attempts to reassert their epistemic dominance. Against this background, the article analyses how the ‘politics of sovereignty’ employed in state actors’ attempts to curb intrusive research are equally present in the realization of cooperative research projects with different national and international (non-governmental) organizations/networks, whose members enact the research cooperation or hamper it in different ways, sometimes in ambiguous, sometimes in obvious manner. Further reflection is provided on the emotional and psychological factors which playing a role in the negotiation of access and the shaping of the overall research project. In conclusion, it is argued that the decisions, views and behaviour of people at the forefront of knowledge production in the global periphery cannot be subjected to moral binaries but need to be understood in terms of the role played by spontaneous reactions, inter-subjective sense-making processes and evaluations of people and projects over time.
The framework developed in this paper can deal with scenarios where selected sub-ontologies of a large ontology are offered as views to users, based on contexts like the access rights of a user, the ...trust level required by the application, or the level of detail requested by the user. Instead of materializing a large number of different sub-ontologies, we propose to keep just one ontology, but equip each axiom with a label from an appropriate context lattice. The different contexts of this ontology are then also expressed by elements of this lattice. For large-scale ontologies, certain consequences (like the subsumption hierarchy) are often pre-computed. Instead of pre-computing these consequences for every context, our approach computes just one label (called a boundary) for each consequence such that a comparison of the user label with the consequence label determines whether the consequence follows from the sub-ontology determined by the context. We describe different black-box approaches for computing boundaries, and present first experimental results that compare the efficiency of these approaches on large real-world ontologies. Black-box means that, rather than requiring modifications of existing reasoning procedures, these approaches can use such procedures directly as sub-procedures, which allows us to employ existing highly-optimized reasoners. Similar to designing ontologies, the process of assigning axiom labels is error-prone. For this reason, we also address the problem of how to repair the labelling of an ontology in case the knowledge engineer notices that the computed boundary of a consequence does not coincide with her intuition regarding in which context the consequence should or should not be visible.
There has been much confusion in property rights inquiry into real (immovable) property (i.e., land) between open access and common property, and between public property and common property because ...that is often also open access. This paper argues that the property rights and access control are two distinct dimensions of land resource management. Access control involves the exercise of exclusionary power relevant to the management of the immovable property (property management) for its optimal use. A review of the literature shows that definitions of property management tend to be too narrow but point towards the need to articulate issues within the property rights paradigm. As a contribution to sustainable resource use as a dimension of land planning, this paper points out and discusses the probable sources of the confusion between land property rights and property management. A “Land Property Rights and Management Matrix” (LPRMM) is developed as a theoretical tool for clarifying the confusion and the relationships amongst relevant concepts. The LPRMM is theoretically informed by Barzel’s not entirely correct distinction between legal (de jure) and economic (de facto) rights and enriched by relevant literature on property rights and property management. Practical use of the LPRMM is illustrated by its application to analyze the issues pertaining to the actual resource-use phenomena in colonial military buildings erected on both private and public land in Hong Kong. The results show that heritage buildings on land under public ownership as private property can be neglected or intensively managed. The LPRMM is not only a useful theoretical tool for precisely assessing the actual affairs of resource use but also a practical tool for identifying issues of property management in its widest sense. The LPRMM offered is a proper interpretation of Barzel’s distinction between legal and economic rights and contributes to systematically re-interpreting property management as town planning writ large in terms of de jure property rights and de facto access.
Background
Observed reductions in firearm suicides in Australia have been linked to the 1997 national firearms agreement (NFA) introduced following the 1996 Port Arthur massacre. The NFA placed ...strong access restrictions on firearms.
Aims
To assess the impact of legislative restrictions on the incidence of firearm suicide in Queensland and explore alternative or contributory factors behind observed declines.
Method
The Queensland suicide register (QSR) provided detailed information on all male suicides in Queensland (1990–2004), with additional data for Australia (1968–2004) accessed from other official sources. Trends in suicide rates pre/post NFA, and in method selection, were assessed using negative binomial regressions. Changing method selection patterns were examined using a cohort analysis of 5 years of age classes for Australian males.
Results
The observed reduction in firearms suicides was initiated prior to the 1997 introduction of the NFA in Queensland and Australia, with a clear decline observed in Australian figures from 1988. No significant difference was found in the rate pre/post the introduction of the NFA in Queensland; however, a significant difference was found for Australian data, the quality of which is noticeably less satisfactory. A marked age-difference in method choice was observed through a cohort analysis demonstrating both time and age influences. Within sequential birth cohorts, rates of firearms suicides decreased in younger males but increased in hanging suicides; this trend was far less marked in older males.
Conclusions
The implemented restrictions may not be responsible for the observed reductions in firearms suicide. Data suggest that a change in social and cultural attitudes could have contributed to the shift in method preference.
This paper explores the impact of the re-introduction of access restrictions to forests in Tanzania, through participatory forest management (PFM), that have excluded villagers from forests to which ...they have traditionally, albeit illegally, had access to collect non-timber forest products (NTFPs). Motivated by our fieldwork, and using a spatial–temporal model, we focus on the paths of forest degradation and regeneration and villagers' utility before and after an access restriction is introduced. Our paper illustrates a number of key points for policy makers. First, the benefits of forest conservation tend to be greatest in the first few periods after an access restriction is introduced, after which the overall forest quality often declines. Second, villagers may displace their NTFP collection into more distant forests that may have been completely protected by distance alone before access to a closer forest was restricted. Third, permitting villagers to collect limited amounts of NTFPs for a fee, or alternatively fining villagers caught collecting illegally from the protected forest, and returning the fee or fine revenue to the villagers, can improve both forest quality and villagers' livelihoods.
► The benefits of forest conservation may be greatest in the first few periods after an access restriction is introduced. ► After an access restriction is introduced, villagers may displace their forest resource collection into more distant forests that were previously fully protected by distance alone. ► Permitting villagers to collect limited amounts of forest products for a fee, or alternatively fining villagers caught collecting illegally from the protected forest, and returning the fee or fine revenue to the villagers, can improve both forest quality and villagers' livelihoods.
To examine existing evidence on the effectiveness of interventions that are designed to prevent the illegal sale of tobacco to young people. The review considers specific sub-questions related to the ...factors that might influence effectiveness, any differential effects for different sub-populations of youth, and barriers and facilitators to implementation.
A review of studies on the impact of interventions on young people under the age of 18 was conducted. It included interventions that were designed to prevent the illegal sale of tobacco to children and young people. The review was conducted in July 2007, and included 20 papers on access restriction studies. The quality of the papers was assessed and the relevant data was extracted.
The evidence obtained from the review indicates that access restriction interventions may produce significant reductions in the rate of illegal tobacco sales to youth. However, lack of enforcement and the ability of youth to acquire cigarettes from social sources may undermine the effectiveness of these interventions.
When access interventions are applied in a comprehensive manner, they can affect young people's access to tobacco. However, further research is required to examine the effects of access restriction interventions on young people's smoking behaviour.
Aim of this work is to evaluate the overall effect of social origins on secondary school track enrolment in Italy, Germany and Netherlands, allowing for consistent cross country comparisons. Track ...choices are assumed to depend on student’s ability and social origins; since proficiency before tracking is not observed, ability is not kept under control. Nonetheless, the unconditional social background effect is the quantity of main substantive interest because it represents the total effect of social origins on school choices. Yet, since regression coefficients in logit models are biased even with independent unobserved heterogeneity, comparison across countries are difficult; the average sample derivative of the response probability is employed and it is showed to be a valid alternative measure of the total social origins effect. The following issue is also addressed: social origins inequality in secondary school choices may be affected by access restrictions policies, at work in some countries, where enrolment into the academic track is subject to binding school recommendations or ability tests. First, we propose a simple theoretical model and derive that the policy is expected to lower the effect of social origins conditional on ability, although the impact on the total effect can either decrease or increase. Second, by exploiting the institutional differences across German Länder with respect to enrolment policies, we carry out a preliminary empirical analysis within Germany. The main empirical findings are: (i) the total effect of social origins on track choice is weaker in the Netherlands and stronger in Germany, with Italy in between; (ii) within Germany, access restriction seem to weaken the parental background effect.
Low-emission zones are currently one of several tools which are in use for the improvement of air quality thanks to the limited entry of vehicles to European city centres. This article describes ...basic characteristics and parameters of low-emission zones in comparison with other types of used restrictions and explains the evaluation system of particularly environmental benefits and impacts. These theoretic assumptions are confronted with established low-emission zones in selected European urban areas; measured benefits and impacts of individual measures are evaluated and compared.
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