Goldstone boson counting in linear sigma models with chemical potential

We analyze the effects of finite chemical potential on spontaneous breaking of internal symmetries within the class of relativistic field theories described by the linear sigma model. Special attention is paid to the emergence of ``abnormal'' Goldstone bosons with quadratic dispersion relation. We show that their presence is tightly connected to nonzero density of the Noether charges, and formulate a general counting rule. The general results are demonstrated on an SU(3)xU(1) invariant model with an SU(3)-sextet scalar field, which describes one of the color-superconducting phases of QCD.Comment: 10 pages, REVTeX4, 4 eps figures, v2: general discussion in Sec. IV expanded and improved, references added, other minor corrections throughout the tex

qq-Trinomial identities

We obtain connection coefficients between $q$-binomial and $q$-trinomial coefficients. Using these, one can transform $q$-binomial identities into a $q$-trinomial identities and back again. To demonstrate the usefulness of this procedure we rederive some known trinomial identities related to partition theory and prove many of the conjectures of Berkovich, McCoy and Pearce, which have recently arisen in their study of the $\phi_{2,1}$ and $\phi_{1,5}$ perturbations of minimal conformal field theory.Comment: 21 pages, AMSLate

An audit of the utility of the D-dimer test in the diagnosis of pulmonary embolism in a private emergency unit in Johannesburg

Background: The D-Dimer test has a high negative predictive value used primarily to exclude clinically suspected possible thrombo-embolic disease. In Emergency Unit (EU) practice, this test is often done not only for suspected Pulmonary Emboli (PE) but also to rule out atypical PE. In South Africa, diagnostic usefulness of this test has not been evaluated in a private hospital EU. The health profile of patients presenting in public and private EUs is different and therefore, it was hypothesized that the usefulness of the DDimer test in these two settings may be different. Results of this study may inform private hospital EU best practice in the optimal utilization of this test. Objective: To evaluate the usefulness of the D-Dimer test in the diagnosis of PE at the Morningside MediClinic (MMC) private hospital EU in Johannesburg, South Africa. Patients and Methods: After approval by the University of the Witwatersrand Human Research Ethics Committee, audit of clinical records was done at the MMC EU from 1 March to 1 June 2009. Informed consent was not required from study subjects as the study was done retrospectively with data extracted from clinical records in an anonymous and delinked fashion. The study population included all patients who had a D-Dimer test done in the MMC EU as part of their diagnostic workup. Extracted data included demographic information, diagnoses and confirmatory tests done. Continuous and categorical variables of data collected were summarized using Stastistica version 9.0 statistical package. A Wells Score was calculated according to the Wells Criteria. Results: In the study period, 189 of 2948 (5%) patients seen at MMC EU had D-Dimers measured. Their population mean age was 57 years (range 38 – 84 years) and 51% were males. Positive D-Dimers were present in 40 (21%) of the total patient population sample group (189 patients). Within the diagnostic categories, the following percentages were the results found per category of the positive D-Dimers within each category: PE (5)(100%), Chest Infection (5)(56%), AMI (2)(33%), Arrhythmia (2)(33%), Hypertension (2)(25%), Chest Pain (6)(14%), Anxiety (3)(23%), Headache (1)(14%), Syncope (1)(14%) and Others (13)(32%). The mean Wells Score in PE was 3.6 (3.0-4.5.) indicating medium probability of PE. All other diagnostic groups had low probability Wells Scores. It was impossible to comment on findings in public hospitals, as there is no known literature found to date on an audit performed concerning the usefulness of the D-Dimer test in a public hospital or any of the public sector, in Johannesburg or elsewhere in South Africa, regarding the diagnosis of PE. However, data has been published by other countries regarding the D-Dimer in various hospital and EU settings (public and private). Conclusion: In the cohort, the D-Dimer was done in only a fifth of patients seen at the private MMC EU and it was positive in less than half of cases. The test yield was highest in PE and had high negative predictive value in more than half of non-PE diagnoses. Therefore, the results suggested that a positive D-Dimer is highly predictive of a diagnosis of PE in this private EU. A negative D-Dimer result appears to be largely associated with any of the non PE wide differential of diagnoses

Precise calculation of transition frequencies of hydrogen and deuterium based on a least-squares analysis

We combine a limited number of accurately measured transition frequencies in hydrogen and deuterium, recent quantum electrodynamics (QED) calculations, and, as an essential additional ingredient, a generalized least-squares analysis, to obtain precise and optimal predictions for hydrogen and deuterium transition frequencies. Some of the predicted transition frequencies have relative uncertainties more than an order of magnitude smaller than that of the g-factor of the electron, which was previously the most accurate prediction of QED.Comment: 4 pages, RevTe

A non-symmetric Yang-Baxter Algebra for the Quantum Nonlinear Schr\"odinger Model

We study certain non-symmetric wavefunctions associated to the quantum nonlinear Schr\"odinger model, introduced by Komori and Hikami using Gutkin's propagation operator, which involves representations of the degenerate affine Hecke algebra. We highlight how these functions can be generated using a vertex-type operator formalism similar to the recursion defining the symmetric (Bethe) wavefunction in the quantum inverse scattering method. Furthermore, some of the commutation relations encoded in the Yang-Baxter equation for the relevant monodromy matrix are generalized to the non-symmetric case.Comment: 31 pages; added some references; minor corrections throughou

FlaA1, a New Bifunctional UDP-GlcNAc C6Dehydratase/ C4 Reductase from Helicobacter pylori

FlaA1 is a small soluble protein of unknown function in Helicobacter pylori. It has homologues that are essential for the virulence of numerous medically relevant bacteria. FlaA1 was overexpressed as a histidine-tagged protein and purified to homogeneity by nickel chelation and cation exchange chromatography. Spectrophotometric assays, capillary electrophoresis, and mass spectrometry analyses showed that FlaA1 is a novel bifunctional C(6) dehydratase/C(4) reductase specific for UDP-GlcNAc. It converts UDP-GlcNAc into a UDP-4-keto-6-methyl-GlcNAc intermediate, which is stereospecifically reduced into UDP-QuiNAc. Substrate conversions as high as 80% were obtained at equilibrium. The K(m) and V(max) for UDP-GlcNAc were 159 microm and 65 pmol/min, respectively. No exogenous cofactor was required to obtain full activity of FlaA1. Additional NADH was only used with poor efficiency for the reduction step. The biochemical characterization of FlaA1 is important for the elucidation of biosynthetic pathways that lead to the formation of 2,6-deoxysugars in medically relevant bacteria. It establishes unambiguously the first step of the pathway and provides the means of preparing the substrate UDP-QuiNAc, which is necessary for the study of downstream enzymes

Zassenhaus conjecture for central extensions of S5

We confirm a conjecture of Zassenhaus about rational conjugacy of torsion units in integral group rings for a covering group of the symmetric group S5 and for the general linear group GLð2; 5Þ. The first result, together with others from the literature, settles the conjugacy question for units of prime-power order in the integral group ring of a finite Frobenius group

Conformal approach to cylindrical DLA

We extend the conformal mapping approach elaborated for the radial Diffusion Limited Aggregation model (DLA) to the cylindrical geometry. We introduce in particular a complex function which allows to grow a cylindrical cluster using as intermediate step a radial aggregate. The grown aggregate exhibits the same self-affine features of the original cylindrical DLA. The specific choice of the transformation allows us to study the relationship between the radial and the cylindrical geometry. In particular the cylindrical aggregate can be seen as a radial aggregate with particles of size increasing with the radius. On the other hand the radial aggregate can be seen as a cylindrical aggregate with particles of size decreasing with the height. This framework, which shifts the point of view from the geometry to the size of the particles, can open the way to more quantitative studies on the relationship between radial and cylindrical DLA.Comment: 16 pages, 8 figure

Recurrence for discrete time unitary evolutions

We consider quantum dynamical systems specified by a unitary operator U and an initial state vector \phi. In each step the unitary is followed by a projective measurement checking whether the system has returned to the initial state. We call the system recurrent if this eventually happens with probability one. We show that recurrence is equivalent to the absence of an absolutely continuous part from the spectral measure of U with respect to \phi. We also show that in the recurrent case the expected first return time is an integer or infinite, for which we give a topological interpretation. A key role in our theory is played by the first arrival amplitudes, which turn out to be the (complex conjugated) Taylor coefficients of the Schur function of the spectral measure. On the one hand, this provides a direct dynamical interpretation of these coefficients; on the other hand it links our definition of first return times to a large body of mathematical literature.Comment: 27 pages, 5 figures, typos correcte

Personal non-commercial use only

ABSTRACT. Objective. Rheumatoid arthritis (RA) is a chronic inflammatory polyarthritis; while the cause is unknown, it has been speculated that an infectious agent could be the trigger for the disease. Numerous attempts at isolating an agent have been unsuccessful. Our purpose was to identify a virus from diseased tissue from a patient with RA. Methods. Diseased tissue taken at the time of knee replacement surgery from a patient with RA was inoculated into several cell lines and observed for cytopathic effect. Cells from the tissue were also grown as explants and were examined for viruses. Synovial fluid drawn 4 years prior to the surgery and frozen at -70°C was also inoculated into cell lines. Following the development of a cytopathic effect and identification of the agent, sera from 50 patients with rheumatoid factor (RF)-negative RA were examined for IgM antibodies to the agent. Results. After many inoculations and numerous subpassages, measles virus was identified in 6 cell lines inoculated with either the minced tissue or synovial fluid. Six cell lines co-cultivated with one or more of 9 explants also showed the presence of measles virus. Measles virus was confirmed by immunofluorescence and by neutralization. Eleven of 50 (22%) sera samples from patients with RF-negative RA had IgM antibodies to measles virus recombinant nucleoprotein. Conclusion. There is an association between measles virus an