Electrical tree structures generated by the ab-initio discharge-avalanche model

Initially the discharge-avalanche model for electrical tree formation treated the local Poisson fields as being derived from the applied Laplace field via a modification factor that was regarded as a random variable in time and space. Recently we have removed this approximation by calculating the local Poisson fields from the space charge arrangement produced by discharges in the tree tubules and avalanches in the surrounding polymer. This “ab-initio” version of the model has now been fully implemented. The ac-cycle is divided into 16 time segments. In each time segment tube-discharges are allowed to occur if the potential difference along a tube is greater than an onset threshold. Positive space charge is regarded as being deposited on the tube walls in the form of positive ions. Negative charge is allowed to penetrate the polymer where it can be used to initiate avalanches and thereby generate damage. The avalanches compete with a field dependant mobility in rearranging the charge around the tree tips

The use of contracting out : a case study of decision-making and organisational learning in local government

One objective of government is to provide services at least cost whilst maintaining or improving service quality. While this may be an important objective, questions are being asked whether services can be provided more efficiently and effectively by the private rather than by the government sector. The shift of service provision from the public to the private sector is known as outsourcing or contracting out. The objective in this study is to critically examine whether the contracting out of services by local government to the private sector is an efficient management practice.The contracting out of Parks and Grounds Maintenance services for the City of Kingston in the State of Victoria, Australia, is used as an exploratory case study to identify the variables associated with management decision-making in the contracting out process. Factors relevant to the contracting out decision such as the criteria used in selecting a contractor; the evaluation of a contractor&rsquo;s performance; and any subsequent changes to management practice relating to the contracting out of the services are identified and discussed.Political forces were found to be an important consideration in the initial contracting out decision, and the selection of a contractor was influenced by the potential to avoid costs. It was also found that under-bidding and associated cost /profit constraints lead to contractors engaging in non-sustainable environmental practices which resulted in the degradation of the local government&rsquo;s Parks and Gardens assets. A sustainable asset management philosophy as opposed to an avoidable costs approach now underpins the contracting out process to ensure the preservation of such assets. Further, administrative processes have been revised to make tender specifications more prescriptive, critical components of services have been brought back in-house, and management practices have been amended so that a greater degree of control is exercised over contractors&rsquo; activities.<br /

THE BEEF COW-CALF ENTERPRISE IN THE GEORGIA PIEDMONT: A CASE STUDY IN CONSPICUOUS PRODUCTION

Livestock Production/Industries,

Early Science with the Karoo Array Telescope: a Mini-Halo Candidate in Galaxy Cluster Abell 3667

Abell 3667 is among the most well-studied galaxy clusters in the Southern Hemisphere. It is known to host two giant radio relics and a head-tail radio galaxy as the brightest cluster galaxy. Recent work has suggested the additional presence of a bridge of diffuse synchrotron emission connecting the North-Western radio relic with the cluster centre. In this work, we present full-polarization observations of Abell 3667 conducted with the Karoo Array Telescope at 1.33 and 1.82 GHz. Our results show both radio relics as well as the brightest cluster galaxy. We use ancillary higher-resolution data to subtract the emission from this galaxy, revealing a localised excess, which we tentatively identify as a radio mini-halo. This mini-halo candidate has an integrated flux density of $67.2\pm4.9$ mJy beam$^{-1}$ at 1.37 GHz, corresponding to a radio power of P$_{\rm{1.4\,GHz}}=4.28\pm0.31\times10^{23}$ W Hz$^{-1}$, consistent with established trends in mini-halo power scaling.Comment: 17 pages, 10 figures, accepted MNRA

Towards a High Energy Theory for the Higgs Phase of Gravity

Spontaneous Lorentz violation due to a time-dependent expectation value for a massless scalar has been suggested as a method for dynamically generating dark energy. A natural candidate for the scalar is a Goldstone boson arising from the spontaneous breaking of a U(1) symmetry. We investigate the low-energy effective action for such a Goldstone boson in a general class of models involving only scalars, proving that if the scalars have standard kinetic terms then at the {\em classical} level the effective action does not have the required features for spontaneous Lorentz violation to occur asymptotically $(t \to \infty)$ in an expanding FRW universe. Then we study the large $N$ limit of a renormalizable field theory with a complex scalar coupled to massive fermions. In this model an effective action for the Goldstone boson with the properties required for spontaneous Lorentz violation can be generated. Although the model has shortcomings, we feel it represents progress towards finding a high energy completion for the Higgs phase of gravity.Comment: 20 pages, 5 figures;fixed typos and added reference