On the Sutherland's Integrability Condition for Two-Dimensional N-Particle Systems

Following Sutherland's work on one-dimensional integrable systems we formulate and study its two-dimensional version. Physically it expresses the absence of true 3-body forces among an assembly of N particles leaving exclusively effective 2-body interactions. This criterion may be a suitable candidate for an integrability condition.Comment: 13 pages,uses LATeX2e and epsf. File prepared using the uufiles packag

Congestion Charging and the Optimal Provision of Public Infrastructure: Theory and Evidence

The paper provides a theoretical framework for analysing the effects of public infrastructure provision on private sector productivity using the example of a transport network. Public infrastructure such as a transport network is assumed to be a (congested) public good. When the provision of this good is at the long run equilibrium level, consumers pay a price which reflects the (individually-determined) marginal productivity of the good and the supplier is also recovering all its opportunity costs. In the traditional literature on transport congestion (Walters, 1961; Mohring and Harwitz, 1962), the concept of infrastructure capacity is often defined in term of the maximum level of traffic flow, which is more of a usage concept rather than a ‘capacity’ concept. Congestion is then defined in terms of the difference between the marginal social cost of this traffic flow and the marginal private costs. There has been some debate in the literature on the way travel demand in general, and traffic congestion in particular, has been defined in terms of traffic flow because this will tend to give an ambiguous definition of the concept of ‘congestion’ in some cases. An alternative measure for the concept of traffic demand (and supply), and of ‘congestion’, is in terms of traffic density or volume rather than in terms of traffic flow. In this paper, we explore this alternative definition of ‘capacity utilisation’ and of ‘congestion’ in terms of traffic density. We arrive at an alternative definition for the concept of optimal congestion tax that turns out to be more robust. This is because it can be applied, not only to the situation of ‘low congestion’ but also to the case of bottleneck or ‘hyper-congestion’ which is not well analysed in the traditional literature. The paper also illustrates this new concept with some numerical calculations based on empirical observations on an actual road network

Linking discrete choice to continuous demand within the framework of a computable general equilibrium model for the analysis of wider economic impacts of transport investment projects

Discrete choice (DC) models are commonly used as basic building blocks in ‘bottom-up’ models which seek to describe consumer and producer behaviour at a disaggregate level, in contrast to continuous demand (CD) models which are used to describe behaviour at a more aggregate level. At a disaggregate level, choice behaviour is defined in terms of commodities differentiated by qualities or attributes. In contrast, aggregate demand behaviour is defined in terms of broadly defined and generically different commodities. In a DC model, the main focus of analysis is not the total quantity of demand, but rather the relative shares or substitution between the choice alternatives, in contrast to a continuous demand model where the focus is on the aggregate substitution between groups of commodities as well as on the income effects. Seen in this way, there is scope for complementary usage of DC and CD models within the framework of a CGE model where DC models are used to describe the preferences for a narrowly defined set of commodities belonging to a particular sector of an economy whereas CD models are used to describe the interactions between these sectors. In this paper, we describe how DC and CD models can be used in such an integrated fashion in a spatial computable general equilibrium model to inquire into the wider economic impacts of a transport investment project in the Sydney Metropolitan Area

Linking Discrete Choice to Continuous Demand in a Spatial Computable General Equilibrium Model

Discrete choice (DC) models are often used to describe consumer behaviour at a disaggregate level where the choice decision is defined in terms of a set of alternatives (commodities) differentiated mainly by their quality attributes rather than just prices, and individuals making the choice decisions are differentiated by their socio-economic characteristics rather than just income level. DC models therefore are rich in details which are important for policies analysis at a micro or intra-sectoral level (e.g., transport sector, housing sector). In contrast, continuous demand (CD) models are specialized in describing behaviour at an aggregate (inter-sectoral) level (e.g. trade-off between transport and land-use activities). DC and CD models are therefore complements rather than substitutes and increasingly, there is a need to integrate the use of both types of models especially in an economy-wide model to look at the impacts of policies which are implemented at a microeconomic level (e.g. investment in a particular transport network) and yet having impacts which are measured adequately only at an economy-wide level. This paper presents a methodology for integrating the use of DC and CD models in the framework of a computable general equilibrium (economy-wide) model. The paper also illustrates the application of this methodology suggested in an empirical example, taken from a study of the investment in the Northwest Rail network in the Sydney Metropolitan Area (Australia)

Wedges, Cones, Cosmic Strings, and the Reality of Vacuum Energy

One of J. Stuart Dowker's most significant achievements has been to observe that the theory of diffraction by wedges developed a century ago by Sommerfeld and others provided the key to solving two problems of great interest in general-relativistic quantum field theory during the last quarter of the twentieth century: the vacuum energy associated with an infinitely thin, straight cosmic string, and (after an interchange of time with a space coordinate) the apparent vacuum energy of empty space as viewed by an accelerating observer. In a sense the string problem is more elementary than the wedge, since Sommerfeld's technique was to relate the wedge problem to that of a conical manifold by the method of images. Indeed, Minkowski space, as well as all cone and wedge problems, are related by images to an infinitely sheeted master manifold, which we call Dowker space. We review the research in this area and exhibit in detail the vacuum expectation values of the energy density and pressure of a scalar field in Dowker space and the cone and wedge spaces that result from it. We point out that the (vanishing) vacuum energy of Minkowski space results, from the point of view of Dowker space, from the quantization of angular modes, in precisely the way that the Casimir energy of a toroidal closed universe results from the quantization of Fourier modes; we hope that this understanding dispels any lingering doubts about the reality of cosmological vacuum energy.Comment: 28 pages, 16 figures. Special volume in honor of J. S. Dowke

Speech-based recognition of self-reported and observed emotion in a dimensional space

The differences between self-reported and observed emotion have only marginally been investigated in the context of speech-based automatic emotion recognition. We address this issue by comparing self-reported emotion ratings to observed emotion ratings and look at how differences between these two types of ratings affect the development and performance of automatic emotion recognizers developed with these ratings. A dimensional approach to emotion modeling is adopted: the ratings are based on continuous arousal and valence scales. We describe the TNO-Gaming Corpus that contains spontaneous vocal and facial expressions elicited via a multiplayer videogame and that includes emotion annotations obtained via self-report and observation by outside observers. Comparisons show that there are discrepancies between self-reported and observed emotion ratings which are also reflected in the performance of the emotion recognizers developed. Using Support Vector Regression in combination with acoustic and textual features, recognizers of arousal and valence are developed that can predict points in a 2-dimensional arousal-valence space. The results of these recognizers show that the self-reported emotion is much harder to recognize than the observed emotion, and that averaging ratings from multiple observers improves performance

Raising and Multiplying Leaders for Vietnamese Ministries in the Converge Worldwide/Baptist General Conference-U.S.

The purpose of this study is to develop a strategy to raise and multiply godly leaders for the Vietnamese (ConvergeViet) Ministries in Converge Worldwide/Baptist General Conference-U.S. churches and then provide practical approaches for mobilizing, training, coaching, and releasing leaders toward their full potential. Since the Vietnamese Christian population in the United States is less than 2 percent of total Vietnamese population in the United States of nearly two million, there is a great need to raise and multiply leaders in ConvergeViet churches in accordance with the command in Matthew 28:18-20. The focus of this study is to equip ConvergeViet leaders or Christian workers in the United States with a better understanding of the need to raise and multiply godly leaders for ConvergeViet Ministries. This process includes contextually adapting coaching questions and modeling for long-term change, as well as developing guidelines for using this new model in ConvergeViet Ministries-U.S. This study is divided into seven chapters. The first chapter provides a ministry profile of ConvergeViet churches in the United States, while the second investigates the need for leadership development among ConvergeViet churches. The third chapter gives theological perspectives for leadership development, and the fourth addresses theological perspectives for leadership multiplication. The fifth chapter develops strategies of raising and multiplying godly leaders for ConvergeViet Ministries-U.S., the sixth creates ownership of raising and multiplying leaders in ConvergeViet Ministries, and the final chapter describes the implementation of strategies for raising and multiplying leaders for ConvergeViet Ministries in the United States. This study provides biblical foundation and principles of leadership as well as a practically reproducible model of leadership development for other recent immigrant churches in the United States. Content Reader: Kurt Fredrickson, Ph.D

Arousal and Valence Prediction in Spontaneous Emotional Speech: Felt versus Perceived Emotion

In this paper, we describe emotion recognition experiments carried out for spontaneous affective speech with the aim to compare the added value of annotation of felt emotion versus annotation of perceived emotion. Using speech material available in the TNO-GAMING corpus (a corpus containing audiovisual recordings of people playing videogames), speech-based affect recognizers were developed that can predict Arousal and Valence scalar values. Two types of recognizers were developed in parallel: one trained with felt emotion annotations (generated by the gamers themselves) and one trained with perceived/observed emotion annotations (generated by a group of observers). The experiments showed that, in speech, with the methods and features currently used, observed emotions are easier to predict than felt emotions. The results suggest that recognition performance strongly depends on how and by whom the emotion annotations are carried out. \u