Spontaneous symmetry breaking in gauge theories via Bose-Einstein condensation

We propose a mechanism naturally leading to the spontaneous symmetry breaking in a gauge theory. The Higgs field is assumed to have global and gauged internal symmetries. We associate a non zero chemical potential to one of the globally conserved charges commuting with all of the gauge transformations. This induces a negative mass squared for the Higgs field triggering the spontaneous symmetry breaking of the global and local symmetries. The mechanism is general and we test the idea for the electroweak theory in which the Higgs sector is extended to possess an extra global Abelian symmetry. To this symmetry we associate a non zero chemical potential. The Bose-Einstein condensation of the Higgs leads, at tree level, to modified dispersion relations for the Higgs field while the dispersion relations of the gauge bosons and fermions remain undisturbed. The latter are modified through higher order corrections. We have computed some corrections to the vacuum polarizations of the gauge bosons and fermions. To quantify the corrections to the gauge boson vacuum polarizations with respect to the Standard Model we considered the effects on the T parameter. We finally derive the one loop modified fermion dispersion relations.Comment: RevTeX 4, 13 pages. Added references and corrected typo

Recent Experimental Tests of Special Relativity

We review our recent Michelson-Morley (MM) and Kennedy-Thorndike (KT) experiment, which tests Lorentz invariance in the photon sector, and report first results of our ongoing atomic clock test of Lorentz invariance in the matter sector. The MM-KT experiment compares a cryogenic microwave resonator to a hydrogen maser, and has set the most stringent limit on a number of parameters in alternative theories to special relativity. We also report first results of a test of Lorentz invariance in the SME (Standard Model Extension) matter sector, using Zeeman transitions in a laser cooled Cs atomic fountain clock. We describe the experiment together with the theoretical model and analysis. Recent experimental results are presented and we give a first estimate of components of the $\tilde{c}^p$ parameters of the SME matter sector. A full analysis of systematic effects is still in progress, and will be the subject of a future publication together with our final results. If confirmed, the present limits would correspond to first ever measurements of some $\tilde{c}^p$ components, and improvements by 11 and 14 orders of magnitude on others.Comment: 29 pages. Contribution to Springer Lecture Notes, "Special Relativity - Will it survive the next 100 years ?", Proceedings, Potsdam, 200

Sensitivity and specificity of a nested polymerase chain reaction for detection of lentivirus infection in lions (Panthera leo)

Feline immunodeficiency virus (FIV) is a lentivirus in the Retroviridae family that causes lifelong infection in domestic cats. The lentivirus of African lions (Panthera leo), referred to as FIVple, is endemic in certain lion populations in eastern and southern Africa. Lentivirus infection leads to immunologic dysfunction and immunosuppressive disease in domestic cats; however, little is known about the pathogenic effects of infection in lions, nor about the epidemiologic impact on free-ranging and captive populations. Whole blood and serum samples were collected opportunistically from free-ranging lions in Kruger National Park, Republic of South Africa (RSA). Whole blood and serum samples were also collected from captive wild lions in the RSA. A nested polymerase chain reaction (PCR) assay for detection of FIV was performed on all whole blood samples. In addition, serum samples were tested for cross-reactive antibodies to domestic feline lentivirus antigens and puma lentivirus synthetic envelope peptide antigen. The PCR assay successfully amplified the lion lentivirus from African lions. The relative sensitivity and relative specificity were 79% and 100%, respectively, and the positive and negative predictive values were 100% and 67%, respectively. This research represents the first study to compare genetic material with antibody-based methods of lentivirus detection on lions in RSA. Using PCR as an additional diagnostic test for FIV in lions will increase screening sensitivity and will allow viral characterization among circulating isolates and monitoring of changes in the viral epidemiology within geographic regions and populations over time

Unveiling the structural transitions during activation of a CO2 methanation catalyst Ru0/ZrO2 synthesised from a MOF precursor

Available online 5 May 2020Carbon Capture, Utilisation and Storage (CCUS) technologies are utilised to minimise net CO2 emissions and hence mitigate the impact of anthropogenic emissions on the global climate. One example of CO2 utilisation is the production of carbon-neutral methane fuel via catalytic CO2 reduction with H2 (methanation). Thermal activation of a metal impregnated metal-organic framework (MOF), 1 wt%Ru/UiO-66 in the presence of H2 and CO2 provides in situ synthesis of a highly active methanation catalyst: H2 promotes the formation of Ru0 nanoparticles, and CO2 behaves as a mild oxidant to remove framework carbon and promote ZrO2 crystallisation. The nature of the active MOF-derived Ru0/ZrO2 catalyst was studied by PXRD, TEM, and XAS, and the evolution of the parent 1 wt%Ru/UiO-66 during thermal activation monitored in operando by synchrotron PXRD. The Ru impregnated Zr-based MOF collapses on heating in H2 and CO2 to form an amorphous C and Zr containing phase that subsequently crystallises as tetragonal (t-) ZrO2 nanoparticles. These t-ZrO2 nanoparticles undergo a subsequent phase transition to the more stable monoclinic (m-) ZrO2 polymorph. In situ activation of Ru/UiO-66 generates a highly active catalyst for CO2 methanation by transforming the MOF precursor into a (carbonfree) crystalline t-ZrO2 support that stabilises highly dispersed metallic Ru nanoparticles. This insight may guide the rational design of future MOF-derived catalystsRenata Lippi, Anita M. D, Angelo, Chaoen Li, Shaun C. Howard, Ian C. Madsen, Karen Wilson, Adam F. Lee, Christopher J. Sumby, Christian J. Doonan, Jim Patel, Danielle F. Kenned

ESTIMATING GENOME-WIDE COPY NUMBER USING ALLELE SPECIFIC MIXTURE MODELS

Genomic changes such as copy number alterations are thought to be one of the major underlying causes of human phenotypic variation among normal and disease subjects [23,11,25,26,5,4,7,18]. These include chromosomal regions with so-called copy number alterations: instead of the expected two copies, a section of the chromosome for a particular individual may have zero copies (homozygous deletion), one copy (hemizygous deletions), or more than two copies (amplifications). The canonical example is Down syndrome which is caused by an extra copy of chromosome 21. Identification of such abnormalities in smaller regions has been of great interest, because it is believed to be an underlying cause of cancer. More than one decade ago comparative genomic hybridization (CGH)technology was developed to detect copy number changes in a high-throughput fashion. However, this technology only provides a 10 MB resolution which limits the ability to detect copy number alterations spanning small regions. It is widely believed that a copy number alteration as small as one base can have significant downstream effects, thus microarray manufacturers have developed technologies that provide much higher resolution. Unfortunately, strong probe effects and variation introduced by sample preparation procedures have made single-point copy number estimates too imprecise to be useful. CGH arrays use a two-color hybridization, usually comparing a sample of interest to a reference sample, which to some degree removes the probe effect. However, the resolution is not nearly high enough to provide single-point copy number estimates. Various groups have proposed statistical procedures that pool data from neighboring locations to successfully improve precision. However, these procedure need to average across relatively large regions to work effectively thus greatly reducing the resolution. Recently, regression-type models that account for probe-effect have been proposed and appear to improve accuracy as well as precision. In this paper, we propose a mixture model solution specifically designed for single-point estimation, that provides various advantages over the existing methodology. We use a 314 sample database, constructed with public datasets, to motivate and fit models for the conditional distribution of the observed intensities given allele specific copy numbers. With the estimated models in place we can compute posterior probabilities that provide a useful prediction rule as well as a confidence measure for each call. Software to implement this procedure will be available in the Bioconductor oligo packagehttp://www.bioconductor.org)

Signals for Lorentz Violation in Electrodynamics

An investigation is performed of the Lorentz-violating electrodynamics extracted from the renormalizable sector of the general Lorentz- and CPT-violating standard-model extension. Among the unconventional properties of radiation arising from Lorentz violation is birefringence of the vacuum. Limits on the dispersion of light produced by galactic and extragalactic objects provide bounds of 3 x 10^{-16} on certain coefficients for Lorentz violation in the photon sector. The comparative spectral polarimetry of light from cosmologically distant sources yields stringent constraints of 2 x 10^{-32}. All remaining coefficients in the photon sector are measurable in high-sensitivity tests involving cavity-stabilized oscillators. Experimental configurations in Earth- and space-based laboratories are considered that involve optical or microwave cavities and that could be implemented using existing technology.Comment: 23 pages REVTe

Extreme Ultra-Violet Spectroscopy of the Lower Solar Atmosphere During Solar Flares

The extreme ultraviolet portion of the solar spectrum contains a wealth of diagnostic tools for probing the lower solar atmosphere in response to an injection of energy, particularly during the impulsive phase of solar flares. These include temperature and density sensitive line ratios, Doppler shifted emission lines and nonthermal broadening, abundance measurements, differential emission measure profiles, and continuum temperatures and energetics, among others. In this paper I shall review some of the advances made in recent years using these techniques, focusing primarily on studies that have utilized data from Hinode/EIS and SDO/EVE, while also providing some historical background and a summary of future spectroscopic instrumentation.Comment: 34 pages, 8 figures. Submitted to Solar Physics as part of the Topical Issue on Solar and Stellar Flare

Updated meta-analysis of randomized controlled trials comparing conventional excisional haemorrhoidectomy with LigaSure for haemorrhoids

Background:\ud To compare the surgical outcome of haemorrhoidectomy performed using LigaSure bipolar diathermy with conventional haemorrhoidectomy.\ud \ud Methods:\ud Only randomized and alternate allocated studies were included from the major electronic databases using the search terms "ligasure" and "haemorrhoids" Duration of operation, blood loss during operation, postoperative pain score, wound healing, in-hospital stay, time to return to normal activities and complications were assessed.\ud \ud Results:\ud The 11 trials contained a total of 1,046 patients; the largest study was based on 273 patients and two earlier studies were based on 34 patients. No significant gender mismatch between the groups was reported in any of the studies. The patients’ ages were similar between groups in the studies, as was disease severity. All 11 studies reported a shorter duration of the operation when using LigaSure compared to the conventional technique (p<0.001). The postoperative pain score (p=0.001) and blood loss during operation (p=0.001) were significantly reduced. After LigaSure haemorrhoidectomy wound healing (p=0.004) and the return to normal activities (p=0.001) were significantly faster than after conventional haemorrhoidectomy. However, the overall incidence of complications reported was not significantly different (p=0.056).\ud \ud Conclusions:\ud LigaSure is an effective instrument for haemorrhoidectomy which results in less blood loss, quicker wound healing and earlier return to work.\u