Aximo: automated axiomatic reasoning for information update

Aximo is a software written in C++ that verifies epistemic properties of dynamic scenarios in multi-agent systems. The underlying logic of our tool is based on the algebraic axiomatics of Dynamic Epistemic Logic. We also present a new theoretical result: the worst case complexity of the verification problem of Aximo

Trade Openness: An Australian Perspective

Australia’s external trade is relatively low compared with the size of its economy. Indeed, Australia’s openness ratio (exports plus imports as a proportion of GDP) in 2002 was the third-lowest among the 30 OECD countries. This paper seeks to understand Australia’s low openness by analysing the empirical determinants of aggregate country trade. We begin by estimating a standard gravity model of bilateral trade. Although the model appears to fit the bilateral data very well, it does a relatively poor job at fitting countries’ aggregate trade levels, with different methodologies sometimes providing highly conflicting results. The focus of the paper is an equation for country openness. Our equation explains a substantial amount of the variation in how much countries trade using a small number of explanatory variables. We find that the most important determinants of openness are population and a measure of distance to potential trade partners. Countries with larger populations trade less, as do countries that are relatively more remote. Furthermore, after controlling for trade policy there is little evidence of a positive correlation between openness and economic development. While gravity models suggest Australia trades much more than expected, the openness equation suggests that its level of trade is relatively close to what would be expected. The most important factors in explaining Australia’s low openness ratio are its distance to the rest of the world, and to a lesser extent its large geographic size.trade; outward orientation; economic geography; trade liberalisation

Adaptive mesh refinement computation of acoustic radiation from an engine intake

A block-structured adaptive mesh refinement (AMR) method was applied to the computational problem of acoustic radiation from an aeroengine intake. The aim is to improve the computational and storage efficiency in aeroengine noise prediction through reduction of computational cells. A parallel implementation of the adaptive mesh refinement algorithm was achieved using message passing interface. It combined a range of 2nd- and 4th-order spatial stencils, a 4th-order low-dissipation and low-dispersion Runge–Kutta scheme for time integration and several different interpolation methods. Both the parallel AMR algorithms and numerical issues were introduced briefly in this work. To solve the problem of acoustic radiation from an aeroengine intake, the code was extended to support body-fitted grid structures. The problem of acoustic radiation was solved with linearised Euler equations. The AMR results were compared with the previous results computed on a uniformly fine mesh to demonstrate the accuracy and the efficiency of the current AMR strategy. As the computational load of the whole adaptively refined mesh has to be balanced between nodes on-line, the parallel performance of the existing code deteriorates along with the increase of processors due to the expensive inter-nodes memory communication costs. The potential solution was suggested in the end

A meta-analysis of randomized trials of behavioural treatment of depression

Reproduced with permission of the publisher. Copyright © 2008 Cambridge University Press.Background. Depression is a common, disabling condition for which psychological treatments, in particular cognitive behavioural therapies are recommended. Promising results in recent randomized trials have renewed interest in behavioural therapy. This systematic review sought to identify all randomized trials of behavioural therapy for depression, determine the effect of such interventions and examine any moderators of such effect. Method. Randomized trials of behavioural treatments of depression versus controls or other psychotherapies were identified using electronic database searches, previous reviews and reference lists. Data on symptom-level, recovery/ dropout rate and study-level moderators (study quality, number of sessions, severity and level of training) were extracted and analysed using meta-analysis and meta-regression respectively. Results. Seventeen randomized controlled trials including 1109 subjects were included in this meta-analysis. A random-effects meta-analysis of symptom-level post-treatment showed behavioural therapies were superior to controls [standardized mean difference (SMD)-0.70, 95% CI -1.00 to -0.39, k=12, n=459], brief psychotherapy (SMD -0.56, 95% CI -1.0 to -0.12, k=3, n=166), supportive therapy (SMD -0.75, 95% CI -1.37 to -0.14, k=2, n=45) and equal to cognitive behavioural therapy (SMD 0.08, 95% CI -0.14 to 0.30, k=12, n=476). Conclusions. The results in this study indicate behavioural therapy is an effective treatment for depression with outcomes equal to that of the current recommended psychological intervention. Future research needs to address issues of parsimony of such interventions

Understanding Firms' Inflation Expectations Using the Bank of Canada's Business Outlook Survey

Inflation expectations are a key determinant of actual and future inflation and thus matter for the conduct of monetary policy. We study how firms form their inflation expectations using quarterly firm-level data from the Bank of Canada's Business Outlook Survey, spanning the 2001 to 2015 period. The data are aggregated to construct an inflation expectations index. Results based on the index suggest that expectations are not consistent with the rationality assumption but are, still, more complex than purely adaptive expectations. Firms' own unique experiences, such as the dynamics of the prices they expect to pay (wages/inputs), significantly influence aggregate expectations. Expectations are also found to be significantly and positively correlated with movements in oil prices. Most of the preceding results hold at the firm level. The estimation of structural shift specifications suggests that inflation expectations in Canada have drifted downward since the Great Recession. However, the data do not suggest that Canadian businesses' expectations have become unanchored

Understanding firms' inflation expectations using the Bank of Canada's Business Outlook Survey

Inflation expectations are a key determinant of actual and future inflation and thus matter for the conduct of monetary policy. We study how firms form their inflation expectations using quarterly firm-level data from the Bank of Canada's Business Outlook Survey, spanning the 2001 to 2015 period. The data are aggregated to construct an inflation expectations index. Results based on the index suggest that expectations are not consistent with the rationality assumption but are, still, more complex than purely adaptive expectations. Firms' own unique experiences, such as the dynamics of the prices they expect to pay (wages/inputs), significantly influence aggregate expectations. Expectations are also found to be significantly and positively correlated with movements in oil prices. Most of the preceding results hold at the firm level. The estimation of structural shift specifications suggests that inflation expectations in Canada have drifted downward since the Great Recession. However, the data do not suggest that Canadian businesses' expectations have become unanchored

Modelling Backward Travelling Holes in Mixed Traffic Conditions Using an Agent Based Simulation

A spatial queue model in a multi-agent simulation framework is extended by introducing a more realistic behaviour, i.e. backward travelling holes. Space corresponding to a leaving vehicle is not available immediately on the upstream end of the link. Instead, the space travels backward with a constant speed. This space is named a ‘hole’. The resulting dynamics resemble Newell’s simplified kinematic wave model. Furthermore, fundamental diagrams from homogeneous and heterogeneous traffic simulations are presented. The sensitivity of the presented approach is tested with the help of flow density contours

What makes self-help interventions effective in the management of depressive symptoms? Meta-analysis and meta-regression.

Reproduced with permission of the publisher. © 2007 Cambridge University Press.Background. Although self-help interventions are effective in treating depression, less is known about the factors that determine effectiveness (i.e. moderators of effect). This study sought to determine whether the content of self-help interventions, the study populations or aspects of study design were the most important moderators. Method. Randomized trials of the effectiveness of self-help interventions versus controls in the treatment of depressive symptoms were identified using previous reviews and electronic database searches. Data on moderators (i.e. patient populations, study design, intervention content) and outcomes were extracted and analysed using meta-regression. Results. Thirty-four studies were identified with 39 comparisons. Study design factors associated with greater effectiveness were unclear allocation concealment, observer-rated outcome measures and waiting-list control groups. Greater effectiveness was also associated with recruitment in non-clinical settings, patients with existing depression (rather than those ‘at risk ’), contact with a therapist (i.e. guided self-help) and the use of cognitive behavioural therapy (CBT) techniques. However, only guided self-help remained significant in the multivariate analysis [regression coefficient 0.36, 95% confidence interval (CI) 0.05–0.68, p=0.03]. In the subset of guided studies, there were no significant associations between outcomes and the session length, content, delivery mode or therapist background. Conclusions. The results provide some insights into moderators of self-help interventions, which might assist in the design of future interventions. However, the present study did not provide a comprehensive description, and other research methods might be required to identify factors associated with the effectiveness of self-help