Radiation Reaction fields for an accelerated dipole for scalar and electromagnetic radiation

The radiation reaction fields are calculated for an accelerated changing dipole in scalar and electromagnetic radiation fields. The acceleration reaction is shown to alter the damping of a time varying dipole in the EM case, but not the scalar case. In the EM case, the dipole radiation reaction field can exert a force on an accelerated monopole charge associated with the accelerated dipole. The radiation reaction of an accelerated charge does not exert a torque on an accelerated magnetic dipole, but an accelerated dipole does exert a force on the charge. The technique used is that originally developed by Penrose for non-singular fields and extended by the author for an accelerated monopole charge.Comment: 11 page

The Story of The Central Normal College

The purpose of this thesis is to give the story of the Central Normal College at Great Bend from, 1886 to 1902. The idea of such a school took form and grew under the direction of a few people who anticipated the needs and desires of the pioneer settlers

Social Death

This review will outline various ways in which the notion of 'social death’ can be understood, and how they can be related to clinical practice. The idea of social death is used to analytically represent how someone can be identified and treated as if they are ontologically deficient – meaning that they are not seen as being 'fully human.' This impacts on their position within society and how they are interacted with. This review will consider three examples of social death - often distinguished from physical or biological death - that are important for clinical practice: loss of agency and identity; treating people as if they are already dead; and, rituals and bereavement. Recognising that a distinction between social and biological death may not always be helpful, this review will suggest ways in which healthcare practitioners can minimise the likelihood of inadvertently treating someone as 'socially dead'

Urban planning law in Liberia: the case for a transformational approach

This article discusses the need for a fundamental rethinking of urban planning in Liberia with special reference to Monrovia, the capital. Liberia is a post-conflict country and is facing a multitude of problems. One is the very rapid urbanisation of the country. Well over 50% of the population live in urban areas, and over one million people—one third of the population—live in Monrovia, for the most part in informal ‘illegal’ settlements with few facilities. Despite land issues being acknowledged as in need of being tackled as a matter of urgency, little has been done by the Johnson-Sirleaf government since it came to power in 2006. What is needed and what this article argues for is a plan for the development of Monrovia based on the Right to the City with residents given clear rights to land and to participate in the governance of their city. The approach is denominated as a transformational one, taking its inspiration from van der Walt’s approach set out in his Property in the Margins. The need for and the outline of an Urban Transformation Act are set out in the article which concludes with a warning that it cannot be supposed that the residents of Monrovia will continue indefinitely to put up with their very poor living conditions

Acoustic Black Holes from Abelian Higgs Model with Lorentz Symmetry Breaking

In this paper we derive acoustic black hole metrics in the (3+1) and (2+1)-dimensional Abelian Higgs model with Lorentz symmetry breaking. In this set up the sound waves lose the Lorentz boost invariance and suffer a 'birefringence' effect. We have found acoustic black holes and respective Hawking temperatures depending on the Lorentz violating parameter. Furthermore, we obtain an acoustic Kerr-like black hole metric with the Lorentz violating term affecting its rate of loss of mass. We also have shown that for suitable values of the Lorentz violating parameter a wider spectrum of particle wave function can be scattered with increased amplitude by the acoustic black hole.Comment: 12 pages, Latex, no figures, version accepted to Phys. Lett.

Black Hole Thermodynamics and Lorentz Symmetry

Recent developments point to a breakdown in the generalized second law of thermodynamics for theories with Lorentz symmetry violation. It appears possible to construct a perpetual motion machine of the second kind in such theories, using a black hole to catalyze the conversion of heat to work. Here we describe and extend the arguments leading to that conclusion. We suggest the inference that local Lorentz symmetry may be an emergent property of the macroscopic world with origins in a microscopic second law of causal horizon thermodynamics.Comment: 4 pages; v2: Version to appear in Foundations of Physics. Potential counterexamples addressed, argument given applying to LV theories where all speeds (or horizons) coincide, and editing for clarit

Decoherence and entropy of primordial fluctuations II. The entropy budget

We calculate the entropy of adiabatic perturbations associated with a truncation of the hierarchy of Green functions at the first non trivial level, i.e. in a self-consistent Gaussian approximation. We give the equation governing the entropy growth and discuss its phenomenology. It is parameterized by two model-dependent kernels. We then examine two particular inflationary models, one with isocurvature perturbations, the other with corrections due to loops of matter fields. In the first model the entropy grows rapidely, while in the second the state remains pure (at one loop).Comment: 28 page

On the physical meaning of the Unruh effect

We present simple arguments that detectors moving with constant acceleration (even acceleration for a finite time) should detect particles. The effect is seen to be universal. Moreover, detectors undergoing linear acceleration and uniform, circular motion both detect particles for the same physical reason. We show that if one uses a circularly orbiting electron in a constant external magnetic field as the Unruh--DeWitt detector, then the Unruh effect physically coincides with the experimentally verified Sokolov--Ternov effect.Comment: 7 pages, 0 figures references added, small changes in text. To be published JETP Lett

Security of the Fiat-Shamir Transformation in the Quantum Random-Oracle Model

The famous Fiat-Shamir transformation turns any public-coin three-round interactive proof, i.e., any so-called sigma-protocol, into a non-interactive proof in the random-oracle model. We study this transformation in the setting of a quantum adversary that in particular may query the random oracle in quantum superposition. Our main result is a generic reduction that transforms any quantum dishonest prover attacking the Fiat-Shamir transformation in the quantum random-oracle model into a similarly successful quantum dishonest prover attacking the underlying sigma-protocol (in the standard model). Applied to the standard soundness and proof-of-knowledge definitions, our reduction implies that both these security properties, in both the computational and the statistical variant, are preserved under the Fiat-Shamir transformation even when allowing quantum attacks. Our result improves and completes the partial results that have been known so far, but it also proves wrong certain claims made in the literature. In the context of post-quantum secure signature schemes, our results imply that for any sigma-protocol that is a proof-of-knowledge against quantum dishonest provers (and that satisfies some additional natural properties), the corresponding Fiat-Shamir signature scheme is secure in the quantum random-oracle model. For example, we can conclude that the non-optimized version of Fish, which is the bare Fiat-Shamir variant of the NIST candidate Picnic, is secure in the quantum random-oracle model.Comment: 20 page

Hawking radiation from "phase horizons" in laser filaments?

Belgiorno et al have reported on experiments aiming at the detection of (the analogue of) Hawking radiation using laser filaments [F. Belgiorno et al, Phys. Rev. Lett. 105, 203901 (2010)]. They sent intense focused Bessel pulses into a non-linear dielectric medium in order to change its refractive index via the Kerr effect and saw creation of photons orthogonal to the direction of travel of the pluses. Since the refractive index change in the pulse generated a "phase horizon" (where the phase velocity of these photons equals the pulse speed), they concluded that they observed the analogue of Hawking radiation. We study this scenario in a model with a phase horizon and a phase velocity very similar to that of their experiment and find that the effective metric does not quite correspond to a black hole. The photons created in this model are not due to the analogue of black hole evaporation but have more similarities to cosmological particle creation. Nevertheless, even this effect cannot explain the observations -- unless the pulse has significant small scale structure in both the longitudinal and transverse dimensions.Comment: 13 pages RevTeX, 2 figure