Chern-Simons number asymmetry from CP violation at electroweak tachyonic preheating

We consider the creation of non-zero Chern-Simons number in a model of the early Universe, where the Higgs field experiences a fast quench at the end of inflation and subsequently rolls down its potential barrier. Neglecting the expansion, we perform numerical lattice simulations in the Abelian Higgs model in 1+1 dimensions with an added phenomenological C and P violating term during this stage of so-called tachyonic preheating. The results suggest that even the sign of the Chern-Simons and thus baryon number is dependent on the ratio of the Higgs to W mass. We also discuss the appropriate choice of vacuum initial conditions for classical simulations.Comment: 24 pages, 17 figures, added references, published versio

Simulations of Cold Electroweak Baryogenesis: Finite time quenches

The electroweak symmetry breaking transition may supply the appropriate out-of-equilibrium conditions for baryogenesis if it is triggered sufficiently fast. This can happen at the end of low-scale inflation, prompting baryogenesis to occur during tachyonic preheating of the Universe, when the potential energy of the inflaton is transfered into Standard Model particles. With the proper amount of CP-violation present, the observed baryon number asymmetry can be reproduced. Within this framework of Cold Electroweak Baryogenesis, we study the dependence of the generated baryon asymmetry on the speed of the quenching transition. We find that there is a separation between ``fast'' and ``slow'' quenches, which can be used to put bounds on the allowed Higgs-inflaton coupling. We also clarify the strong Higgs mass dependence of the asymmetry reported in a companion paper (hep-ph/0604263).Comment: 18 pages, 20 figure

Demonstration of Run-time Spatial Mapping of Streaming Applications to a Heterogeneous Multi-Processor System-on-Chip (MPSOC)

In this paper, the problem of spatial mapping is defined. Reasons are presented to show why performing spatial mappings at run-time is both necessary and desirable and criteria for the qualitative comparison of spatial mappings are introduced. An algorithm is described that implements a preliminary spatial mapper. The methods used in the algorithm are demonstrated with an illustrative example

A flashback on the dawn of the meteorite impact/extinction theory

Presented are my personal recollections on some of the major contributions by the Alvarez groups to the birth and development of the meteorite impact/extinction theory

Equilibration in phi^4 theory in 3+1 dimensions

The process of equilibration in phi^4 theory is investigated for a homogeneous system in 3+1 dimensions and a variety of out-of-equilibrium initial conditions, both in the symmetric and broken phase, by means of the 2PI effective action. Two Phi-derivable approximations including scattering effects are used: the two-loop and the ``basketball'', the latter corresponding to the truncation of the 2PI effective action at O(lambda^2). The approach to equilibrium, as well as the kinetic and chemical equilibration is investigated.Comment: 32 pages, 14 figures, uses axodraw, minor corrections adde

Quantized Anomalous Hall Effect in Two-Dimensional Ferromagnets - Quantum Hall Effect from Metal -

We study the effect of disorder on the anomalous Hall effect (AHE) in two-dimensional ferromagnets. The topological nature of AHE leads to the integer quantum Hall effect from a metal, i.e., the quantization of $\sigma_{xy}$ induced by the localization except for the few extended states carrying Chern number. Extensive numerical study on a model reveals that Pruisken's two-parameter scaling theory holds even when the system has no gap with the overlapping multibands and without the uniform magnetic field. Therefore the condition for the quantized AHE is given only by the Hall conductivity $\sigma_{xy}$ without the quantum correction, i.e., $|\sigma_{xy}| > e^2/(2h)$.Comment: 5 pages, 4 figures, REVTe

An Investigation into the Use of Microchemistry Experiments in First-year University-level Practicals

In the case study reported on in this article the desirability to convert first-year university-level practicals in chemistry from conventional techniques to microscale methods was investigated. The results indicated that microscale experiments did not result in a noticeable saving in time and gave results that compare favourably with those of the conventional experiments. The most positive aspect of microscale experiments is a long-term financial one. A few negative aspects of microscale experiments were identified in the study. In hierdie bydrae word 'n gevallestudie gerapporteer oor die wenslikheid om eerstevlak universiteitschemie-prakties van konvensionele tegnieke na mikroskaaltegnieke om te skakel. Die resultate toon dat die mikroskaaleksperimente nie noemenswaardig tydsbesparend is nie en resultate lewer wat goed vergelyk met di? van konvensionele eksperimente. Die mees positiewe aspek van mikroskaaleksperimente is finansi?le besparing op die lang termyn. Enkele negatiewe aspekte van mikroskaaleksperimente is in die ondersoek ge?dentifiseer. Keywords: Microscale, Practicals, Chemicals, Microchemistry, First-level South African Journal of Chemistry Vol.57 2004: 19-2

Intravitreal Administration of Human Bone Marrow CD34+ Stem Cells in a Murine Model of Retinal Degeneration.

PurposeIntravitreal murine lineage-negative bone marrow (BM) hematopoietic cells slow down retinal degeneration. Because human BM CD34+ hematopoietic cells are not precisely comparable to murine cells, this study examined the effect of intravitreal human BM CD34+ cells on the degenerating retina using a murine model.MethodsC3H/HeJrd1/rd1 mice, immunosuppressed systemically with tacrolimus and rapamycin, were injected intravitreally with PBS (n = 16) or CD34+ cells (n = 16) isolated from human BM using a magnetic cell sorter and labeled with enhanced green fluorescent protein (EGFP). After 1 and 4 weeks, the injected eyes were imaged with scanning laser ophthalmoscopy (SLO)/optical coherence tomography (OCT) and tested with electroretinography (ERG). Eyes were harvested after euthanasia for immunohistochemical and microarray analysis of the retina.ResultsIn vivo SLO fundus imaging visualized EGFP-labeled cells within the eyes following intravitreal injection. Simultaneous OCT analysis localized the EGFP-labeled cells on the retinal surface resulting in a saw-toothed appearance. Immunohistochemical analysis of the retina identified EGFP-labeled cells on the retinal surface and adjacent to ganglion cells. Electroretinography testing showed a flat signal both at 1 and 4 weeks following injection in all eyes. Microarray analysis of the retina following cell injection showed altered expression of more than 300 mouse genes, predominantly those regulating photoreceptor function and maintenance and apoptosis.ConclusionsIntravitreal human BM CD34+ cells rapidly home to the degenerating retinal surface. Although a functional benefit of this cell therapy was not seen on ERG in this rapidly progressive retinal degeneration model, molecular changes in the retina associated with CD34+ cell therapy suggest potential trophic regenerative effects that warrant further exploration

Tachyonic preheating using 2PI-1/N dynamics and the classical approximation

We study the process of tachyonic preheating using approximative quantum equations of motion derived from the 2PI effective action. The O(N) scalar (Higgs) field is assumed to experience a fast quench which is represented by an instantaneous flip of the sign of the mass parameter. The equations of motion are solved numerically on the lattice, and the Hartree and 1/N-NLO approximations are compared to the classical approximation. Classical dynamics is expected to be valid, since the occupation numbers can rise to large values during tachyonic preheating. We find that the classical approximation performs excellently at short and intermediate times, even for couplings in the larger region currently allowed for the SM Higgs. This is reassuring, since all previous numerical studies of tachyonic preheating and baryogenesis during tachyonic preheating have used classical dynamics. We also compare different initializations for the classical simulations.Comment: 32 pages, 21 figures. Published version: Some details added, section added, references added, conclusions unchange

When should root remnants and unrestorable broken teeth be extracted in frail older adults?

BACKGROUND: Many frail older adults have an unhealthy dentition; unrestorable broken teeth and root remnants with open root canals, commonly accompanied by periapical and periodontal inflammation, are often seen. Improving oral health in the growing group of frail older adults with remaining teeth is a considerable challenge for dental care professionals. Dentists are often uncertain how to deal with root remnants and unrestorable broken teeth in frail older adults. METHODS: The authors aim was to provide recommendations to dentists to help in their clinical decision making about the extraction or retention of roots remnants and broken teeth in frail older adults. CONCLUSIONS: Decisions about the extraction or retention of root remnants should made on the basis of preventing pain and oral discomfort, preventing severe inflammation, and preventing additional decline in oral health. Both root-related and patient-related factors are considered. PRACTICAL IMPLICATIONS: Decision-making trees can help dentists decide whether to extract root remnants and unrestorable broken teeth in frail older adults