11 research outputs found

    Lagrangian and Hamiltonian formulations of higher order Chern-Simons theories

    Get PDF
    We consider models involving the higher (third) derivative extension of the abelian Chern-Simons (CS) topological term in D=2+1 dimensions. The polarisation vectors in these models reveal an identical structure with the corresponding expressions for usual models which contain, at most, quadratic structures. We also investigate the Hamiltonian structure of these models and show how Wigner's little group acts as gauge generator.Comment: 13 pages, Late

    Dual composition of odd-dimensional models

    Full text link
    A general way of interpreting odd dimensional models as a doublet of chiral models is discussed. Based on the equations of motion this dual composition is illustrated. Examples from quantum mechanics, field theory and gravity are considered. Specially the recently advocated topologically massive gravity is analysed in some details.Comment: minor modification

    Self dual models and mass generation in planar field theory

    Full text link
    We analyse in three space-time dimensions, the connection between abelian self dual vector doublets and their counterparts containing both an explicit mass and a topological mass. Their correspondence is established in the lagrangian formalism using an operator approach as well as a path integral approach. A canonical hamiltonian analysis is presented, which also shows the equivalence with the lagrangian formalism. The implications of our results for bosonisation in three dimensions are discussed.Comment: 15 pages,Revtex, No figures; several changes; revised version to appear in Physical Review

    Invasion and Killing of Human Endothelial Cells by Viridans Group Streptococci

    No full text
    Colonization of the cardiovascular endothelium by viridans group streptococci can result in infective endocarditis and possibly atherosclerosis; however, the mechanisms of pathogenesis are poorly understood. We investigated the ability of selected oral streptococci to infect monolayers of human umbilical vein endothelial cells (HUVEC) in 50% human plasma and to produce cytotoxicity. Planktonic Streptococcus gordonii CH1 killed HUVEC over a 5-h period by peroxidogenesis (alpha-hemolysin) and by acidogenesis but not by production of protein exotoxins. HUVEC were protected fully by addition of supplemental buffers and bovine liver catalase to the culture medium. Streptococci were also found to invade HUVEC by an endocytic mechanism that was dependent on polymerization of actin microfilaments and on a functional cytoskeleton, as indicated by inhibition with cytochalasin D and nocodazole. Electron microscopy revealed streptococci attached to HUVEC surfaces via numerous fibrillar structures and bacteria in membrane-encased cytoplasmic vacuoles. Following invasion by S. gordonii CH1, HUVEC monolayers showed 63% cell lysis over 4 h, releasing 64% of the total intracellular bacteria into the culture medium; however, the bacteria did not multiply during this time. The ability to invade HUVEC was exhibited by selected strains of S. gordonii, S. sanguis, S. mutans, S. mitis, and S. oralis but only weakly by S. salivarius. Comparison of isogenic pairs of S. gordonii revealed a requirement for several surface proteins for maximum host cell invasion: glucosyltransferase, the sialic acid-binding protein Hsa, and the hydrophobicity/coaggregation proteins CshA and CshB. Deletion of genes for the antigen I/II adhesins, SspA and SspB, did not affect invasion. We hypothesize that peroxidogenesis and invasion of the cardiovascular endothelium by viridans group streptococci are integral events in the pathogenesis of infective endocarditis and atherosclerosis

    Spinal anesthesia during cesarean section and persisting low back pain: a cross sectional study in West Bengal, India

    Get PDF
    Background: Spinal anesthesia related spinal injury can be a major issue in elevating back pain. Several evidences have established this process as a significant contributor of back pain; though contradictions are also present. This study aims to focus on the consequences of back pain associated with the effects of spinal anesthesia that have been received before several years. Methodology: 48 housewives are included in this study (20 subjects for vaginal delivery and 28 subjects for spinal anaesthesia induced cesarean section) based on convenient sampling method through assessing their socio-economic status and other attributing criteria. Pain detect tool was used to track back pain status and a semi structure questionnaire was used to explore other considerations. Results: Results have shown significant differences in pain responses after receiving spinal anesthesia (exposed group) than control group. Subjects have reflected significant differences in their pain perception scores. Conclusion: This study concludes that subjects have shown significant higher pain perception levels after receiving spinal anesthesia compared to general anesthesia. Decision of Cesarean section delivery should include patientÔÇÖs previous pain conditions and current need. Acute care in post surgical pain should be immediately addressed even after several months of the surgery

    Type I Interferon Receptor is a Primary Regulator of Target-Mediated Drug Disposition of Interferon-╬▓ in Mice

    No full text
    The purpose of this study is to evaluate the primary mechanism through which interferon (IFN)-╬▓ exhibits target-mediated drug disposition (TMDD) and whether the theoretical assumptions of TMDD models are consistent with experimental pharmacokinetic (PK) data. Recombinant murine IFN-╬▓ was administered as an intravenous injection at two dose levels (0.5 and 1 million IU/kg) to male wild-type (WT) and type-I IFN-╬▒/╬▓ receptor subunit (IFNAR-1) knockout (KO) mice (A129S7/SvEvBrd strain). Sampling was conducted at various times (n = 3/time point), and plasma was analyzed for IFN-╬▓ concentrations using a validated enzyme-linked immunosorbent assay. The pharmacodynamic (PD) biomarker was IP-10 mRNA that was isolated from the distal femur bone and quantified using reverse transcription-polymerase chain reaction. An integrated model that includes rapid-binding TMDD and an indirect mechanism of drug action was used to characterize the PK/PD profiles. For an experimental control, PK profiles of recombinant murine erythropoietin (muEPO), another drug that exhibits TMDD, were determined after a single intravenous dose (0.5 ╬╝g/kg) in WT and KO animals. The concentration-time profiles for IFN-╬▓ differed substantially at initial times for the WT and KO mice at the same dose levels. These differences are characteristic of ligands exhibiting receptor-mediated disposition and were well described by a rapid-binding TMDD model. No differences in muEPO PK were observed in the control study. In summary, the intact IFNAR receptor is a primary regulator of in vivo IFN-╬▓ exposure. An integrated PK/PD model was successfully used to assess the receptor-mediated disposition and dynamics of IFN-╬▓

    Seven-quasiparticle bands in Ce-139

    No full text
    The high spin states in the Ce-139 nucleus have been studied by in-beam gamma-spectroscopic techniques using the reaction Te-130(C-12,3n)Ce-139 at E-beam=65 MeV. A gamma detector array, consisting of five Compton-suppressed Clover detectors was used for coincidence measurements. 15 new levels have been proposed and 28 new gamma transitions have been assigned to Ce-139 on the basis of gamma gamma coincidence data. The level scheme of Ce-139 has been extended above the known 70 ns 19/2 isomer up to similar to 6.1 MeV in excitation energy and 35/2h in spin. The spin-parity assignments for most of the newly proposed levels have been made using the deduced Directional Correlation from Oriented states of nuclei (DCO ratio) and the Polarization Directional Correlation from Oriented states (PDCO ratio) for the de-exciting transitions. The observed level structure has been compared with a large basis shell model calculation and also with the predictions from cranked Nilsson-Strutinsky (CNS) calculations. A general consistency has been observed between these two different theoretical approaches
    corecore