The unified transform method for linear initial-boundary value problems: a spectral interpretation

It is known that the unified transform method may be used to solve any well-posed initial-boundary value problem for a linear constant-coefficient evolution equation on the finite interval or the half-line. In contrast, classical methods such as Fourier series and transform techniques may only be used to solve certain problems. The solution representation obtained by such a classical method is known to be an expansion in the eigenfunctions or generalised eigenfunctions of the self-adjoint ordinary differential operator associated with the spatial part of the initial-boundary value problem. In this work, we emphasise that the unified transform method may be viewed as the natural extension of Fourier transform techniques for non-self-adjoint operators. Moreover, we investigate the spectral meaning of the transform pair used in the new method; we discuss the recent definition of a new class of spectral functionals and show how it permits the diagonalisation of certain non-self-adjoint spatial differential operators.Comment: 3 figure

An approach for uncertainty aggregation using generalised conjunction/disjunction aggregators

Decision Support Systems are often used in the area of system evaluation. The quality of the output of such a system is only as good as the quality of the data that is used as input. Uncertainty on data, if not taken into account, can lead to evaluation results that are not representative. In this paper, we propose a technique to extend Generalised Con- junction/Disjunction aggregators to deal with un- certainty in Decision Support Systems. We first de- fine the logic properties of uncertainty aggregation through reasoning on strict aggregators and after- wards extend this logic to partial aggregators

Conceptual models of urban environmental information systems - toward improved information provision

Cities are the hub of European society - for over a millennium, they are the locus of social, political and economic development. As the core of intensive and creative human activity, they are also the place where the environmental externalities that accompany rapid development are most visible. The environmental consequences of urban development have been recognised long ago, as in the case of London, where in 1388 legislation was introduced to control pollutant emissions (Lowenthal, 1990). Similar historical environmental regulations can be demonstrated for many cities in Europe. However, while for most of history those who govern the city (be it the sovereign, city elders or local government) where responsible for the control, mitigation and management of the common environment in the city, the last 30 years are a period of profound change. This is due to the trend toward improved participation in environmental decision making . a more inclusive and open approach to decisions that deal with the city commons. This change did not occurre overnight but rather gradually. For example, in the United Kingdom, it was the Town and Country Planning Act of 1947 which introduced public scrutiny to changes in the urban form (Rydin, 1998), or the development of public involvement in environmental impact assessment of urban projects as developed in many countries throughout the developed world during the 1970s and 1980s (Gilpin 1995). These changes accelerate within the last three decades, and especially since the publication of .Our Common Future. (WCED and Brundtland 1987), the acceptance of the .Sustainable Development. principles and the Rio conference. A quiet (mini) revolution happened in Europe not long ago, toward the end of 1998 when the members of the United Nations Economic Commission for Europe (UN/ECE) signed the .Convention on Access to Information, Public Participation in Decision Making and Access to Justice in Environmental Matters. - the Aarhus Convention (UN/ECE 1998). The convention is expected to come into force by the end of 2001, and calls the governments and public authorities to open up access to environmental information as a means to improve public participation in environmental decision making and awareness of environmental issues (UN/ECE, 1998). However, these declarations on the value and importance of environmental information do not match our level of understanding on the role of environmental information in decision making processes, and especially on the role of information in improving awareness and participation. Therefore, it is useful to take a step back, and to try and evaluate how environmental information and access to it and its use support public involvement in such processes. This paper is aimed to offer a framework that can assist us in the analytical process of understanding environmental information use. It focuses on public access and assumes that environmental information will be delivered to the public through the Internet. Such assumption is based on the current trend within public authorities is to use Information and Communication Technology (ICT) as a major delivery medium and it seems that it will become more so in the near future (OECD 2000). The framework which this paper presents, is based on Soft Systems Methodology (SSM) study which unpacked some of the core issues relating to public access and use of environmental information (Haklay, 2001). Although the aim here is not to discuss the merits of SSM, but to focus on the conceptual models, some introduction to the techniques that are used here is needed. Therefore, the following section opens with introduction to SSM and its techniques. The core of the paper is dedicated to the development of conceptual models. After presenting the conceptual models, some conclusions about these models and their applications are drown

Economic evaluations of non-communicable disease interventions

Background Demographic projections suggest a major increase in non-communicable disease (NCD) mortality over the next two decades in developing countries. In a climate of scarce resources, policy-makers need to know which interventions represent value for money. The prohibitive cost of performing multiple economic evaluations has generated interest in transferring the results of studies from one setting to another. This paper aims to bridge the gap in the current literature by critically evaluating the available published data on economic evaluations of NCD interventions in developing countries. Methods We identified and reviewed the methodological quality of 32 economic evaluations of NCD interventions in developing countries. Developing countries were defined according to the World Bank classification for low- and lower middle-income countries. We defined NCDs as the 12 categories listed in the 1993 World Bank report Investing in Health. English language literature was searched for the period January 1984 and January 2003 inclusive in Medline, Science Citation Index, HealthStar, NHS Economic Evaluation Database and Embase using medical subheading terms and free text searches. We then assessed the quality of studies according to a set of pre-defined technical criteria. Results We found that the quality of studies was poor and resource allocation decisions made by local and global policy-makers on the basis of this evidence could be misleading. Furthermore we have identified some clear gaps in the literature, particularly around injuries and strategies for tackling the consequences of the emerging tobacco epidemic. Conclusion In the face of poor evidence the role of so-called generalised cost-effectiveness analyses has an important role to play in aiding public health decision-making at the global level. Further research is needed to investigates the causes of variation among cost, effects and cost-effectiveness data within and between settings. Such analyses still need to take a broad view, present data in a transparent manner and take account of local constraints