Spherical Solutions due to the Exterior Geometry of a Charged Weyl Black Hole

Firstly we derive peculiar spherical Weyl solutions, using a general spherically symmetric metric due to a massive charged object with definite mass and radius. Afterwards, we present new analytical solutions for relevant cosmological terms, which appear in the metrics. Connecting the metrics to a new geometric definition of a charged Black Hole, we numerically investigate the effective potentials of the total dynamical system, considering massive and massless test particles, moving on such Black Holes.Comment: 8 pages, 5 figure

Bioinspired low-frequency material characterisation

New-coded signals, transmitted by high-sensitivity broadband transducers in the 40–200 kHz range, allow subwavelength material discrimination and thickness determination of polypropylene, polyvinylchloride, and brass samples. Frequency domain spectra enable simultaneous measurement of material properties including longitudinal sound velocity and the attenuation constant as well as thickness measurements. Laboratory test measurements agree well with model results, with sound velocity prediction errors of less than 1%, and thickness discrimination of at least wavelength/15. The resolution of these measurements has only been matched in the past through methods that utilise higher frequencies. The ability to obtain the same resolution using low frequencies has many advantages, particularly when dealing with highly attenuating materials. This approach differs significantly from past biomimetic approaches where actual or simulated animal signals have been used and consequently has the potential for application in a range of fields where both improved penetration and high resolution are required, such as nondestructive testing and evaluation, geophysics, and medical physics

Leader, follower or free rider? The economic impacts of different Australian emission targets

This economic analysis by policy experts from CSIRO, The Climate Institute, Monash University and McLennan Magasanik Associates examined a range of scenarios to explore the relative costs of Australia free riding and following other industrialised countries in the global efforts to avoid dangerous climate change versus Australia taking a leadership position. It concludes that making very substantial reductions in Australia\u27s net greenhouse emissions is affordable, and compatible with continuing growth in incomes, employment and living standards.&nbsp

Rapid non-contacting resistivity logging of core

We demonstrate a non-contact approach to whole-core and split-core resistivity measurements, imaging a 15 mm-thick, dipping, conductive layer, producing a continuous log of the whole core and enabling the development of a framework to allow representative plugs to be taken, for example. Applications include mapping subtle changes in grain fabric (e.g. grain shape) caused by variable sedimentation rates, for example, as well as the well-known dependencies on porosity and water saturation. The method operates at relatively low frequencies (i.e. low induction numbers), needing highly sensitive coil pairs to provide resistivity measurements at the desired resolution. A four-coil arrangement of two pairs of transmitter and receiver coils is used to stabilize the measurement. One ‘coil pair’ acts as a control, enabling the effects of local environmental variations, which can be considerable, to be removed from the measurement at source. Comparing our non-contact approach and independent traditional ‘galvanic’ resistivity measurements indicates that the non-contact measurements are directly proportional to the reciprocal of the sample resistivity (i.e. conductivity). The depth of investigation is discussed in terms of both theory and practical measurements, and the response of the technique to a variety of synthetic ‘structures’ is presented. We demonstrate the potential of the technique for rapid electrical imaging of core and present a whole-core image of a dipping layer with azimuthal discrimination at a resolution of the order of 10 mm. Consequently, the technique could be used to investigate different depths within the core, in agreement with theoretical predictions

Optical Link of the Atlas Pixel Detector

The on-detector optical link of the ATLAS pixel detector contains radiation-hard receiver chips to decode bi-phase marked signals received on PIN arrays and data transmitter chips to drive VCSEL arrays. The components are mounted on hybrid boards (opto-boards). We present results from the irradiation studies with 24 GeV protons up to 32 Mrad (1.2 x 10^15 p/cm^2) and the experience from the production.Comment: 9th ICATPP Conference, Como, Ital

Minimal Riesz energy on the sphere for axis-supported external fields

We investigate the minimal Riesz s-energy problem for positive measures on the d-dimensional unit sphere S^d in the presence of an external field induced by a point charge, and more generally by a line charge. The model interaction is that of Riesz potentials |x-y|^(-s) with d-2 <= s < d. For a given axis-supported external field, the support and the density of the corresponding extremal measure on S^d is determined. The special case s = d-2 yields interesting phenomena, which we investigate in detail. A weak* asymptotic analysis is provided as s goes to (d-2)^+.Comment: 42 pages, 2 figure

Methods for the recognition of geological weakness zones and other surface discontinuities caused by underground mining in Carboniferous terrain

Since March 1992 the British Geological Survey (BGS) has collaborated in a CEC part-funded project under the leadership of Dr Clasen of Saarberg, Saarbrueken, Germany. The aim of this project was to determine the most efficient combination of surface geophysical techniques to be used in combination with airborne optical scanning data for the routine detection of shallow faults. Such features, when reactivated following undermining, may become the locii of damaging subsidence, but where they can be traced in advance of mining operations then remedial measures (such as underpinning etc) may be undertaken. This final report outlines the geophysical methods applied and describes our most significant results. Conclusions are drawn concerning the relative efficiencies of each technique and possible complementary applications

Influence of heavy modes on perturbations in multiple field inflation

We investigate linear cosmological perturbations in multiple field inflationary models where some of the directions are light while others are heavy (with respect to the Hubble parameter). By integrating out the massive degrees of freedom, we determine the multi-dimensional effective theory for the light degrees of freedom and give explicitly the propagation matrix that replaces the effective sound speed of the one-dimensional case. We then examine in detail the consequences of a sudden turn along the inflationary trajectory, in particular the possible breakdown of the low energy effective theory in case the heavy modes are excited. Resorting to a new basis in field space, instead of the usual adiabatic/entropic basis, we study the evolution of the perturbations during the turn. In particular, we compute the power spectrum and compare with the result obtained from the low energy effective theory.Comment: 24 pages, 13 figures; v2 substantial changes in sec.V; v3 matching the published version on JCA