Can type II Semi-local cosmic strings form?

We present the simplest possible model for a semi-local string defect in which a U(1) gauged subgroup of an otherwise global SU(2) is broken to produce local cosmic strings endowed with current-carrying properties. Restricting attention to type II vortices for which the non current-carrying state is unstable, we show that a condensate must form microscopically and macroscopically evolve towards a chiral configuration. It has been suggested that such configurations could potentially exist in a stable state, thereby inducing large cosmological consequences based on equilibrium angular momentum supported loop configurations (vortons). Here we show that the current itself induces a macroscopic (longitudinal) instability: we conclude that type II semi-local cosmic strings cannot form in a cosmological context.Comment: 11 pages, 5 figure

The speech community

The speech community (SpCom), a core concept in empirical linguistics, is at the intersection of many principal problems in sociolinguistic theory and method. This paper traces its history of development and divergence, surveys general problems with contemporary notions, and discusses links to key issues in investigating language variation and change. It neither offers a new and correct definition nor rejects the concept (both are seen as misguided efforts), nor does it exhaustively survey the applications in the field (an impossibly large task)

Reconciling model and information uncertainty in development appraisal

This paper investigates the effect of choices of model structure and scale in development viability appraisal. The paper addresses two questions concerning the application of development appraisal techniques to viability modelling within the UK planning system. The first relates to the extent to which, given intrinsic input uncertainty, the choice of model structure significantly affects model outputs. The second concerns the extent to which, given intrinsic input uncertainty, the level of model complexity significantly affects model outputs. Monte Carlo simulation procedures are applied to a hypothetical development scheme in order to measure the effects of model aggregation and structure on model output variance. It is concluded that, given the particular scheme modelled and unavoidably subjective assumptions of input variance, simple and simplistic models may produce similar outputs to more robust and disaggregated models

Bouncing alternatives to inflation

Although the inflationary paradigm is the most widely accepted explanation for the current cosmological observations, it does not necessarily correspond to what actually happened in the early stages of our Universe. To decide on this issue, two paths can be followed: first, all the possible predictions it makes must be derived thoroughly and compared with available data, and second, all imaginable alternatives must be ruled out. Leaving the first task to all other contributors of this volume, we concentrate here on the second option, focusing on the bouncing alternatives and their consequences.Comment: 11 pages, 3 figures, submitted as a contribution to the French 'Comptes Rendus de l'Academie des Sciences' on Inflatio

A Critical Review of Classical Bouncing Cosmologies

Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The Planck data shows an unmistakably red, quasi scale-invariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result. We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research.Comment: 60 pages, 20 figures, review articl

Ceramic micropalaeontology: the analysis of microfossils in ancient ceramics

Microfossils can be a common component of ancient ceramic artefacts. Their analysis in this unusual context is a little-known, yet promising cross-disciplinary application of micropalaeontology. The following article presents the first detailed assessment of the phenomenon of microfossils in ancient ceramics and demonstrates how micropalaeontology can contribute to a range of issues in archaeological ceramic analysis and the reconstruction of the human past. In describing a methodology by which micropalaeontologists and archaeologists can analyse microfossiliferous ceramics, this paper presents the foundations of an approach, which is here referred to as Ceramic Micropalaeontology