753 research outputs found
Topological and Nontopological Solitons in a Gauged O(3) Sigma Model with Chern-Simons term
The nonlinear sigma model with its subgroup gauged, where the
gauge field dynamics is solely governed by a Chern-Simons term, admits both
topological as well as nontopological self-dual soliton solutions for a
specific choice of the potential. It turns out that the topological solitons
are infinitely degenerate in any given sector.Comment: Few minor changes have been made. To appear in Phys. Lett.
Representation of South Asian people in randomised clinical trials: analysis of trials' data
Excluding patients of ethnic minority groups from clinical
trials is unethical, introduces substantial bias, and
means that findings are based on unrepresentative
populations. The National Institutes of Health Revitalization
Act 1993 requires that all minority groups be represented
in the sample in research projects supported
by the National Institutes of Health, unless there is a
clear and compelling justification not to do so. In the
United Kingdom no such legislation exists
Self-dual Gauged Models
We consider a model with the subgroup completely gauged, where
. The gauge field dynamics is solely governed by a nonabelian
Chern-Simons term and the global symmetry is broken explicitly by
introducing a invariant scalar potential. We obtain self-dual equations
of this gauged model and find that the energy is bounded from below by a
linear combination of the topological charge and a global charge present
in the theory. We also discuss on the self-dual soliton solutions of this
model.Comment: 12 Pages, RevTex, few minor changes have been made, to appear in
Physics Letters
Anyonic Bogomol'nyi Solitons in a Gauged O(3) Sigma Model
We introduce the self-dual abelian gauged sigma models where the
Maxwell and Chern-Simons terms constitute the kinetic terms for the gauge
field. These models have quite rich structures and various limits. Our models
are found to exhibit both symmetric and broken phases of the gauge group. We
discuss the pure Chern-Simons limit in some detail and study rotationally
symmetric solitons.Comment: 14 pages, 6 Postscript figures uuencoded, written in REVTe
Image lag optimisation in a 4T CMOS image sensor for the JANUS camera on ESA's JUICE mission to Jupiter
The CIS115, the imager selected for the JANUS camera on ESA’s JUICE mission to Jupiter, is a Four Transistor (4T) CMOS Image Sensor (CIS) fabricated in a 0.18 µm process. 4T CIS (like the CIS115) transfer photo generated charge collected in the pinned photodiode (PPD) to the sense node (SN) through the Transfer Gate (TG). These regions are held at different potentials and charge is transferred from the potential well under PPD to the potential well under the FD through a voltage pulse applied to the TG. Incomplete transfer of this charge can result in image lag, where signal in previous frames can manifest itself in subsequent frames, often appearing as ghosted images in successive readouts. This can seriously affect image quality in scientific instruments and must be minimised. This is important in the JANUS camera, where image quality is essential to help JUICE meet its scientific objectives. This paper presents two techniques to minimise image lag within the CIS115. An analysis of the optimal voltage for the transfer gate voltage is detailed where optimisation of this TG “ON” voltage has shown to minimise image lag in both an engineering model and gamma and proton irradiated devices. Secondly, a new readout method of the CIS115 is described, where following standard image integration, the PPD is biased to the reset voltage level (VRESET) through the transfer gate to empty charge on the PPD and has shown to reduce image lag in the CIS115
Nonlinear Meissner effect in a high-temperature superconductor: Local versus nonlocal electrodynamics
Measured intermodulation distortion (IMD) power at 1.5 GHz in a series of YBa[subscript 2]Y[subscript 3]O[subscript 7−δ] stripline resonators of varying strip widths is compared to the predictions of two qualitatively distinct theories of the nonlinear Meissner effect. The stripline resonators are patterned from a single wafer to ensure uniformity of the material properties. According to the first theory [T. Dahm and D. J. Scalapino, Phys. Rev. B 60, 13125 (1999)], the IMD power is dominated by contributions from the strip edges, while according to the second theory [D. Agassi and D. E. Oates, Phys. Rev. B 72, 014538 (2005)] it is dominated by contributions from the body of the strip. The parameter-free comparison of the measured data with the theoretical predictions clearly favors the latter theory. We conclude that the nonlinear component of the penetration depth must be treated with nonlocal electrodynamics. The origins of this outcome are discussed briefly in the framework of a Green’s-function approach
Improving the economic value of photographic screening for optical coherence tomography-detectable macular oedema : a prospective, multicentre, UK study
Peer reviewedPublisher PD
Field Theory Supertubes
Starting with intersecting M2-branes in M-theory, the IIA supertube can be
found by compactification with a boost to the speed of light in the compact
dimension. A similar procedure applied to Donaldson-Uhlenbeck-Yau instantons on
\bC^3, viewed as intersecting membranes of 7D supersymmetric Yang-Mills (SYM)
theory, yields (for finite boost) a new set of 1/4 BPS equations for 6D
SYM-Higgs theory, and (for infinite boost) a generalization of the dyonic
instanton equations of 5D SYM-Higgs theory, solutions of which are interpreted
as Yang-Mills supertubes and realized as configurations of IIB string theory.Comment: 11 pages. Contribution to Strings '04. Revised to include minor
corrections and additional reference
Polymorphism in <i>INSR</i> Locus Modifies Risk of Atrial Fibrillation in Patients on Thyroid Hormone Replacement Therapy
AimsAtrial fibrillation (AF) is a risk for patients receiving thyroid hormone replacement therapy. No published work has focused on pharmacogenetics relevant to thyroid dysfunction and AF risk. We aimed to assess the effect of L-thyroxine on AF risk stratified by a variation in a candidate gene.Methods and ResultsA retrospective follow-up study was done among European Caucasian patients from the Genetics of Diabetes Audit and Research in Tayside Scotland cohort (Scotland, United Kingdom). Linked data on biochemistry, prescribing, hospital admissions, demographics, and genetic biobank were used to ascertain patients on L-thyroxine and diagnosis of AF. A GWAS-identified insulin receptor-INSR locus (rs4804416) was the candidate gene. Cox survival models and sensitivity analyses by taking competing risk of death into account were used. Replication was performed in additional sample (The Genetics of Scottish Health Research register, GoSHARE), and meta-analyses across the results of the study and replication cohorts were done. We analyzed 962 exposed to L-thyroxine and 5,840 unexposed patients who were rs4804416 genotyped. The rarer G/G genotype was present in 18% of the study population. The total follow-up was up to 20 years, and there was a significant increased AF risk for patients homozygous carriers of the G allele exposed to L-thyroxine (RHR = 2.35, P = 1.6e–02). The adjusted increased risk was highest within the first 3 years of exposure (RHR = 9.10, P = 8.5e–04). Sensitivity analysis yielded similar results. Effects were replicated in GoSHARE (n = 3,190).ConclusionHomozygous G/G genotype at the INSR locus (rs4804416) is associated with an increased risk of AF in patients on L-thyroxine, independent of serum of free thyroxine and thyroid-stimulating hormone serum concentrations
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