A Numerical Solution Using an Adaptively Preconditioned Lanczos Method for a Class of Linear Systems Related with the Fractional Poisson Equation

This study considers the solution of a class of linear systems related with the fractional Poisson equation (FPE) (−∇2)α/2φ=g(x,y) with nonhomogeneous boundary conditions on a bounded domain. A numerical approximation to FPE is derived using a matrix representation of the Laplacian to generate a linear system of equations with its matrix A raised to the fractional power α/2. The solution of the linear system then requires the action of the matrix function f(A)=A−α/2 on a vector b. For large, sparse, and symmetric positive definite matrices, the Lanczos approximation generates f(A)b≈β0Vmf(Tm)e1. This method works well when both the analytic grade of A with respect to b and the residual for the linear system are sufficiently small. Memory constraints often require restarting the Lanczos decomposition; however this is not straightforward in the context of matrix function approximation. In this paper, we use the idea of thick-restart and adaptive preconditioning for solving linear systems to improve convergence of the Lanczos approximation. We give an error bound for the new method and illustrate its role in solving FPE. Numerical results are provided to gauge the performance of the proposed method relative to exact analytic solutions.

Dual-process action of exercise on appetite control : increase in orexigenic drive but improvement in meal-induced satiety

Background: Exercise could contribute to weight loss by altering the sensitivity of the appetite regulatory system. Objective: The aim of this study was to assess the effects of 12 wk of mandatory exercise on appetite control. Design: Fifty-eight overweight and obese men and women [mean (±SD) body mass index (in kg/m2) = 31.8 ± 4.5, age = 39.6 ± 9.8 y, and maximal oxygen intake = 29.1 ± 5.7 mL · kg–1 · min–1] completed 12 wk of supervised exercise in the laboratory. The exercise sessions were designed to expend 2500 kcal/wk. Subjective appetite sensations and the satiating efficiency of a fixed breakfast were compared at baseline (week 0) and at week 12. An Electronic Appetite Rating System was used to measure subjective appetite sensations immediately before and after the fixed breakfast in the immediate postprandial period and across the whole day. The satiety quotient of the breakfast was determined by calculating the change in appetite scores relative to the breakfast's energy content. Results: Despite large variability, there was a significant reduction in mean body weight (3.2 ± 3.6 kg), fat mass (3.2 ± 2.2 kg), and waist circumference (5.0 ± 3.2 cm) after 12 wk. The analysis showed that a reduction in body weight and body composition was accompanied by an increase in fasting hunger and in average hunger across the day (P < 0.0001). Paradoxically, the immediate and delayed satiety quotient of the breakfast also increased significantly (P < 0.05). Conclusions: These data show that the effect of exercise on appetite regulation involves at least 2 processes: an increase in the overall (orexigenic) drive to eat and a concomitant increase in the satiating efficiency of a fixed meal.

Action learning of online marketing via a global contest

Introduction: The Google Online Marketing Challenge is a global competition in which student teams run advertising campaigns for small and medium-sized businesses (SMEs) using AdWords, Google’s text-based advertisements. In 2008, its inaugural year, over 8,000 students and 300 instructors from 47 countries representing over 200 schools participated. The Challenge ran in undergraduate and graduate classes in disciplines such as marketing, tourism, advertising, communication and information systems. Combining advertising and education, the Challenge gives student hands-on experience in the increasingly important field of online marketing, engages them with local businesses and motivates them through the thrill of a global competition. Student teams receive US$200 in AdWords credits, Google’s premier advertising product that offers cost-per-click advertisements. The teams then recruit and work with a local business to devise an effective online marketing campaign. Students first outline a strategy, run a series of campaigns, and provide their business with recommendations to improve their online marketing. Teams submit two written reports for judging by 14 academics in eight countries. In addition, Google AdWords experts judge teams on their campaign statistics such as success metrics and account management. Rather than a marketing simulation against a computer or hypothetical marketing plans for hypothetical businesses, the Challenges has student teams develop and manage real online advertising campaigns for their clients and compete against peers globally.

Krylov subspace methods for approximating functions of symmetric positive definite matrices with applications to applied statistics and anomalous diffusion

Matrix function approximation is a current focus of worldwide interest and finds application in a variety of areas of applied mathematics and statistics. In this thesis we focus on the approximation of A^(-α/2)b, where A ∈ ℝ^(n×n) is a large, sparse symmetric positive definite matrix and b ∈ ℝ^n is a vector. In particular, we will focus on matrix function techniques for sampling from Gaussian Markov random fields in applied statistics and the solution of fractional-in-space partial differential equations. Gaussian Markov random fields (GMRFs) are multivariate normal random variables characterised by a sparse precision (inverse covariance) matrix. GMRFs are popular models in computational spatial statistics as the sparse structure can be exploited, typically through the use of the sparse Cholesky decomposition, to construct fast sampling methods. It is well known, however, that for sufficiently large problems, iterative methods for solving linear systems outperform direct methods. Fractional-in-space partial differential equations arise in models of processes undergoing anomalous diffusion. Unfortunately, as the fractional Laplacian is a non-local operator, numerical methods based on the direct discretisation of these equations typically requires the solution of dense linear systems, which is impractical for fine discretisations. In this thesis, novel applications of Krylov subspace approximations to matrix functions for both of these problems are investigated. Matrix functions arise when sampling from a GMRF by noting that the Cholesky decomposition A = LL^T is, essentially, a `square root' of the precision matrix A. Therefore, we can replace the usual sampling method, which forms x = L^(-T)z, with x = A^(-1/2)z, where z is a vector of independent and identically distributed standard normal random variables. Similarly, the matrix transfer technique can be used to build solutions to the fractional Poisson equation of the form ϕn = A^(-α/2)b, where A is the finite difference approximation to the Laplacian. Hence both applications require the approximation of f(A)b, where f(t) = t^(-α/2) and A is sparse. In this thesis we will compare the Lanczos approximation, the shift-and-invert Lanczos approximation, the extended Krylov subspace method, rational approximations and the restarted Lanczos approximation for approximating matrix functions of this form. A number of new and novel results are presented in this thesis. Firstly, we prove the convergence of the matrix transfer technique for the solution of the fractional Poisson equation and we give conditions by which the finite difference discretisation can be replaced by other methods for discretising the Laplacian. We then investigate a number of methods for approximating matrix functions of the form A^(-α/2)b and investigate stopping criteria for these methods. In particular, we derive a new method for restarting the Lanczos approximation to f(A)b. We then apply these techniques to the problem of sampling from a GMRF and construct a full suite of methods for sampling conditioned on linear constraints and approximating the likelihood. Finally, we consider the problem of sampling from a generalised Matern random field, which combines our techniques for solving fractional-in-space partial differential equations with our method for sampling from GMRFs.

Disappointment and disgust, or teaching?

Is 'disappointment' and 'the teaching of disgust' the core of TV Studies? Or might teaching better be accomplished by inspiring positive civic action. Either way, doesn't reality TV do it better? John Hartley uses examples from reality TV to discuss this question.

Reciprocity : where art meets the community : action research in response to artistic encounters and relationships

This practice-led research project examines some of the factors and issues facing artists working in the public domain who wish to engage with the community as audience. Using the methodology of action research, the three major creative projects in this study use art as a socio-political tool with the aim of providing an effective vehicle for broadening awareness, understanding forms of social protest and increasing tolerance for diversity. The three projects: Floodline November 7, 2004, Look in, Look out, and The Urban Terrorist Project, dealt with issues of marginalisation of communities, audiences and graffiti artists respectively. The artist/researcher is outlined as both creator and collaborator in the work. Processes included ephemeral elements, such as temporary installation and performance, as well as interactive elements that encouraged direct audience involvement as part of the work. In addition to the roles of creator and collaborator, both of which included audience as well as artist, the presence of an outside entity was evident. Whether local, legal authorities or prevailing attitudes, outside entities had an unavoidable impact on the processes and outcomes of the work. Each project elicited a range of responses from their respective audiences; however, the overarching concept of reciprocity was seen to be the crucial factor in conception, artistic methods and outcomes.

Impact of music therapy to promote positive parenting and child development

The effectiveness of a 10-week group music therapy program for marginalized parents and their children aged 0–5 years was examined. Musical activities were used to promote positive parent–child relationships and children’s behavioral, communicative and social development. Participants were 358 parents and children from families facing social disadvantage, young parents or parents of a child with a disability. Significant improvements were found for therapist-observed parent and child behaviors, and parent-reported irritable parenting, educational activities in the home, parent mental health and child communication and social play skills. This study provides evidence of the potential effectiveness of music therapy for early intervention.

User-generated content and the future of public broadcasting : a case study of the special broadcasting service

This thesis presents a case study of the Special Broadcasting Service documenting the broadcasting challenges posed by user-generated content initiatives and the work-place approach to strategies for participation. Using the action research method, the project findings reveal that limitations to resources and funding determined the scope for innovation and that the practice of executive editorial control over content was considered fundamental to fulfilling the responsibilities of the public service mandate. Media workers were overwhelmingly positive about the enhanced productive capabilities of the audience and willing to facilitate moderated interactions, however the effectiveness of these initiatives differed according to the level of skills required. This thesis demonstrates how participatory initiatives can enhance aspects of the public service remit relating to cultural diversity, the servicing of niche interests, and broader social representation, and help reinvigorate the relevance of public service broadcasting in the digitalised media sphere.

Realistic yet humanitarian? The comprehensive plan of action and refugee policy in Southeast Asia

The 1989 Comprehensive Plan of Action (CPA) has recently been described as a successful example of how to manage large protracted refugee flows. However, this article revisits the circumstances surrounding the CPA used to resolve the prolonged Indo-Chinese refugee crisis to highlight that part of its development was linked to the fact that Southeast Asian states refused to engage with proposed solutions, which did not include repatriation for the majority of the Indo-Chinese asylum seekers who were deemed to be ‘non-genuine’1 ( UNGA, 1989a) refugees. This resulted in the CPA often forcibly repatriating ‘non-genuine’ refugees, particularly near the end of its program. This article reviews the CPA in order to assess whether its practices and results should be repeated.

Teaching crabs to walk straight : is there a place for ethics education in Malaysian accountancy courses?

Recent releases from the International Federation of Accountants (IFAC) highlight the importance of ethics education. Academic institutions employ varying methods of teaching ethics and place varying levels of emphasis on ethics teaching during a business/accounting degree. This paper attempts to evaluate whether teaching ethics to final year accountancy students is beneficial. At the commencement of a semester 85 final year accounting students were given five ethical scenarios on which to make an ethical decision. During the semester they were subject to two different methods of teaching ethics, a traditional lecture/tutorial process and a group assignment. ----- After a significant gap, students were re-presented with the ethical scenarios and asked what action they now considered appropriate. In all five instances students offered a more ethical response the second time. When asked to evaluate the methodologies the students considered both training methods to have a positive effect on their ethical thinking. The results suggest it is beneficial to include ethics teaching in accountancy courses, if the profession’s goal of ethical practitioners is to be achieved.

A general approach to control a positive buck-boost converter to achieve robustness against input voltage fluctuations and load changes

A Positive Buck-Boost converter is a known DC-DC converter which may be controlled to act as Buck or Boost converter with same polarity of the input voltage. This converter has four switching states which include all the switching states of the above mentioned DC-DC converters. In addition there is one switching state which provides a degree of freedom for the positive Buck-Boost converter in comparison to the Buck, Boost, and inverting Buck-Boost converters. In other words the Positive Buck-Boost Converter shows a higher level of flexibility for its inductor current control compared to the other DC-DC converters. In this paper this extra degree of freedom is utilised to increase the robustness against input voltage fluctuations and load changes. To address this capacity of the positive Buck-Boost converter, two different control strategies are proposed which control the inductor current and output voltage against any fluctuations in input voltage and load changes. Mathematical analysis for dynamic and steady state conditions are presented in this paper and simulation results verify the proposed method.