Coherent potential approximation, averaged T-matrix approximation and Lloyd's model

It is shown how the single-site coherent potential approximation and the averaged T-matrix approximation become exact in the calculation of the averaged single-particle Green function of the electron in the Anderson model when the site energy is distributed randomly with lorentzian distribution. Using these approximations, Lloyd's exact result is reproduced.

Growing healthy sweetpotato: best practices for producing planting material

Sweetpotato is a major food crop in Papua New Guinea, with about 2.9 million tonnes grown each year. But sweetpotato is prone to pests and diseases, particularly viruses, which can significantly reduce yields. Because there are no varieties known to be resistant to viruses, the next best solution is to produce planting material that is free from infection, and to make this readily available to growers. This manual is aimed at researchers and technicians, and describes how to test for sweetpotato viruses and to keep vines free from infection. The methods described should help locals in PNG and other Pacific nations produce disease-free planting material for sweetpotato and other root and tuber crops.

An algebraic algorithm for the design and analysis of linear dynamical systems

In an earlier paper [1], it has been shown that velocity ratio, defined with reference to the analogous circuit, is a basic parameter in the complete analysis of a linear one-dimensional dynamical system. In this paper it is shown that the terms constituting velocity ratio can be readily determined by means of an algebraic algorithm developed from a heuristic study of the process of transfer matrix multiplication. The algorithm permits the set of most significant terms at a particular frequency of interest to be identified from a knowledge of the relative magnitudes of the impedances of the constituent elements of a proposed configuration. This feature makes the algorithm a potential tool in a first approach to a rational design of a complex dynamical filter. This algorithm is particularly suited for the desk analysis of a medium size system with lumped as well as distributed elements.

Best practice full-stop: Anticipating the spillover effects of enterprise education

This paper considers the potential flow-on benefits that may arise from the increasing provision of enterprise education. The issue of vulnerability is proposed to be a factor associated with superior learning outcomes. Therefore, this paper aims to highlight the use of student and facilitator vulnerability to increase the capacity for learning in Higher Education. It is argued that students benefit from having to struggle to find their identity within a learning environment. That group work can assist the development of confidence through which improved learning behaviours are adopted. Also, the development of good learning practices in the domain of enterprise education have the potential to aid student learning outcomes in other areas of study. This paper provides another means of valuing the potential gains to be received from enterprise education.

An algebraic approach to the restoration of images

Two different matrix algorithms are described for the restoration of blurred pictures. These are illustrated by numerical examples.

Approximation of the perturbation equations of a quasi-linear hyperbolic system in the neighborhood of a bicharacteristic

In 1956 Whitham gave a nonlinear theory for computing the intensity of an acoustic pulse of an arbitrary shape. The theory has been used very successfully in computing the intensity of the sonic bang produced by a supersonic plane. [4.] derived an approximate quasi-linear equation for the propagation of a short wave in a compressible medium. These two methods are essentially nonlinear approximations of the perturbation equations of the system of gas-dynamic equations in the neighborhood of a bicharacteristic curve (or rays) for weak unsteady disturbances superimposed on a given steady solution. In this paper we have derived an approximate quasi-linear equation which is an approximation of perturbation equations in the neighborhood of a bicharacteristic curve for a weak pulse governed by a general system of first order quasi-linear partial differential equations in m + 1 independent variables (t, x1,…, xm) and derived Gubkin's result as a particular case when the system of equations consists of the equations of an unsteady motion of a compressible gas. We have also discussed the form of the approximate equation describing the waves propagating upsteam in an arbitrary multidimensional transonic flow.

What are the 'best buys' in preventing infection following caesarean section?

Caesarean section is the most common surgical procedure performed on women worldwide and infections following caesarean section occur in approximately 10% of Australian women...

An appendix to the paper "approximation of the perturbation equations of a quasi-linear hyperbolic system in the neighborhood of a bicharacteristic"

The theory of Varley and Cumberbatch [l] giving the intensity of discontinuities in the normal derivatives of the dependent variables at a wave front can be deduced from the more general results of Prasad which give the complete history of a disturbance not only at the wave front but also within a short distance behind the wave front. In what follows we omit the index M in Eq. (2.25) of Prasad [2].

Complimentary collaborations: Teachers and researchers co-developing best practices in art education

Australia is currently experiencing a huge cultural shift as it moves from a State-based curriculum, to a national education system. The Australian State-based bodies that currently manage teacher registration, teacher education course accreditation, curriculum frameworks and syllabi are often complex organisations that hold conflicting ideologies about education and teaching. The development of a centralised system, complete with a single accreditation body and a national curriculum can be seen as a reaction to this complexity. At the time of writing, the Australian Curriculum is being rolled out in staggered phases across the states and territories of Australia. Phase one has been implemented, introducing English, Mathematics, History and Science. Subsequent phases (Humanities and Social Sciences, the Arts, Technologies, Health and Physical Education, Languages, and year 9-10 work studies) are intended to follow. Forcing an educational shift of this magnitude is no simple task; not least because the States and Territories have and continue to demonstrate varying levels of resistance to winding down their own curricula in favour of new content with its unfamiliar expectations and organisations. The full implementation process is currently far from over, and far from being fully resolved. The Federal Government has initiated a number of strategies to progress the implementation, such as the development of the Australian Institute for Teaching and School Leadership (AITSL) to aid professional educators to implement the new curriculum. AITSL worked with professional and peak specialist bodies to develop Illustrations of Practice (hereafter IoP) for teachers to access and utilise. This paper tells of the building of one IoP, where a graduate teacher and a university lecturer collaborated to construct ideas and strategies to deliver visual arts lessons to early childhood students in a low Socio- Economic Status [SES] regional setting and discusses the experience in terms of its potential for professional learning in art education.

A curve shortening flow rule for closed embedded plane curves with a prescribed rate of change in enclosed area

Motivated by a problem from fluid mechanics, we consider a generalization of the standard curve shortening flow problem for a closed embedded plane curve such that the area enclosed by the curve is forced to decrease at a prescribed rate. Using formal asymptotic and numerical techniques, we derive possible extinction shapes as the curve contracts to a point, dependent on the rate of decreasing area; we find there is a wider class of extinction shapes than for standard curve shortening, for which initially simple closed curves are always asymptotically circular. We also provide numerical evidence that self-intersection is possible for non-convex initial conditions, distinguishing between pinch-off and coalescence of the curve interior.

With the best of intentions: A critical discourse analysis of HPE curriculum materials

Much of physical education curriculum in the developed world and specifically in Australia tends to be guided in principle by syllabus documents that represent, in varying degrees, some form of government education priorities. Through the use of critical discourse analysis we analyze one such syllabus example (an official syllabus document of one of the Australian States) to explore the relationships between the emancipatory/social justice expectations presented in the rubric of and introduction to the official syllabus document, and the language details of learning outcomes that indicate how the expectations might be satisfied. Given the complexity and multilevel pathways of message systems/ideologies we question the efficacy of such documents oriented around social justice principles to genuinely deliver more radical agendas which promote social change and encourage a preparedness to engage in social action leading to a betterment of society.

The alpha method for solving differential algebraic inequality (DAI) systems

This paper describes an algorithm for ``direct numerical integration'' of the initial value Differential-Algebraic Inequalities (DAI) in a time stepping fashion using a sequential quadratic programming (SQP) method solver for detecting and satisfying active path constraints at each time step. The activation of a path constraint generally increases the condition number of the active discretized differential algebraic equation's (DAE) Jacobian and this difficulty is addressed by a regularization property of the alpha method. The algorithm is locally stable when index 1 and index 2 active path constraints and bounds are active. Subject to available regularization it is seen to be stable for active index 3 active path constraints in the numerical examples. For the high index active path constraints, the algorithm uses a user-selectable parameter to perturb the smaller singular values of the Jacobian with a view to reducing the condition number so that the simulation can proceed. The algorithm can be used as a relatively cheaper estimation tool for trajectory and control planning and in the context of model predictive control solutions. It can also be used to generate initial guess values of optimization variables used as input to inequality path constrained dynamic optimization problems. The method is illustrated with examples from space vehicle trajectory and robot path planning.