744 research outputs found

    Isolation of cDNA clones encoding the human Sm B/B′auto-immune antigen and specifically reacting with human anti-Sm auto-immune sera

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    AbstractA cDNA clone for the human SmB and B′ auto-immune antigens has been isolated by antibody screening of a cDNA expression library. The cDNA clone hybridises with two distinct mRNAs, one of which is expressed in a tissue-specific manner. A fusion protein expressed from the cDNA clone was recognised by a number of sera from systemic lupus erythematosus (SLE) patients containing anti-Sm antibodies but not by sera reactive with other auto-immune antigens. The potential use of this clone in a diagnostic assay for SLE and in elucidating the processes regulating the expression of SmB and B′ is discussed

    Pulse dispersion in glass fibres

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    Measurements indicate that pulses incident normally on the end of a cladded multimode fibre are broadened by less than 0.1 ns over a length of 20 m. The measured dispersions in lengths of 20 m and 35 m do not exceed 5 ps/m. However, with an angle of incidence of 17°, or with a defocused input beam, the pulses are broadened by 0.6 ns

    Effect of a Normal-State Pseudogap on Optical Conductivity in Underdoped Cuprate Superconductors

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    We calculate the c-axis infrared conductivity σc(ω)\sigma_c(\omega) in underdoped cuprate superconductors for spinfluctuation exchange scattering within the CuO2_2-planes including a phenomenological d-wave pseudogap of amplitude EgE_g. For temperatures decreasing below a temperature T∗∼Eg/2T^* \sim E_g/2, a gap for ω<2Eg\omega < 2E_g develops in σc(ω)\sigma_c(\omega) in the incoherent (diffuse) transmission limit. The resistivity shows 'semiconducting' behavior, i.e. it increases for low temperatures above the constant behavior for Eg=0E_g=0. We find that the pseudogap structure in the in-plane optical conductivity is about twice as big as in the interplane conductivity σc(ω)\sigma_c(\omega), in qualitative agreement with experiment. This is a consequence of the fact that the spinfluctuation exchange interaction is suppressed at low frequencies as a result of the opening of the pseudogap. While the c-axis conductivity in the underdoped regime is described best by incoherent transmission, in the overdoped regime coherent conductance gives a better description.Comment: to be published in Phys. Rev. B (November 1, 1999

    Propagation model for multimode optical-fibre waveguide

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    Pulse dispersions of 5 ps/m have been measured in cladded-glass and liquid-core multimode fibres. A theoretical model is proposed which gives excellent agreement with measured propagation delay and pulse dispersion. In the fibres used, there is little light scattering either in the core or at the core-cladding interface

    Dietary lecithin improves the healthiness of pork

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    Dietary lecithin may provide health benefits to pork as well as improving its eating quality by reducing chewiness and hardness (D'Souza et al.., 2005). Human studies have shown lecithin supplementation can reduce cholesterol significantly (Spilburg et al., 2003) and we hypothesised that lecithin supplementation would have a similar effect in pigs. The use of lecithin supplementation to improve the 'healthiness' of pork or pork products, while also improving the tenderness of pork, could provide the pork industry with significant marketing opportunities. The aim of this experiment was to investigate the effect of lecithin supplementation on the fatty acid profile of pork and also on the plasma cholesterol of pigs

    Vortex structure in d-density wave scenario of pseudogap

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    We investigate the vortex structure assuming the d-density wave scenario of the pseudogap. We discuss the profiles of the order parameters in the vicinity of the vortex, effective vortex charge and the local density of states. We find a pronounced modification of these quantities when compared to a purely superconducting case. Results have been obtained for a clean system as well as in the presence of a nonmagnetic impurity. We show that the competition between superconductivity and the density wave may explain some experimental data recently obtained for high-temperature superconductors. In particular, we show that the d-density wave scenario explains the asymmetry of the gap observed in the vicinity of the vortex core.Comment: 8 pages, 10 figure

    An Immunocompetent Mouse Model of HPV16(+) Head and Neck Squamous Cell Carcinoma

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    The incidence of human papilloma virus (HPV)-associated head and neck squamous cell carcinoma (HNSCC) is increasing and implicated in more than 60% of all oropharyngeal carcinomas (OPSCCs). Although whole-genome, transcriptome, and proteome analyses have identified altered signaling pathways in HPV-induced HNSCCs, additional tools are needed to investigate the unique pathobiology of OPSCC. Herein, bioinformatics analyses of human HPV(+) HNSCCs revealed that all tumors express full-length E6 and identified molecular subtypes based on relative E6 and E7 expression levels. To recapitulate the levels, stoichiometric ratios, and anatomic location of E6/E7 expression, we generated a genetically engineered mouse model whereby balanced expression of E6/E7 is directed to the oropharyngeal epithelium. The addition of a mutant PIK3CAE545K allele leads to the rapid development of pre-malignant lesions marked by immune cell accumulation, and a subset of these lesions progress to OPSCC. This mouse provides a faithful immunocompetent model for testing treatments and investigating mechanisms of immunosuppression

    A Planck-scale axion and SU(2) Yang-Mills dynamics: Present acceleration and the fate of the photon

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    From the time of CMB decoupling onwards we investigate cosmological evolution subject to a strongly interacting SU(2) gauge theory of Yang-Mills scale Λ∼10−4\Lambda\sim 10^{-4} eV (masquerading as the U(1)YU(1)_{Y} factor of the SM at present). The viability of this postulate is discussed in view of cosmological and (astro)particle physics bounds. The gauge theory is coupled to a spatially homogeneous and ultra-light (Planck-scale) axion field. As first pointed out by Frieman et al., such an axion is a viable candidate for quintessence, i.e. dynamical dark energy, being associated with today's cosmological acceleration. A prediction of an upper limit Δtmγ=0\Delta t_{m_\gamma=0} for the duration of the epoch stretching from the present to the point where the photon starts to be Meissner massive is obtained: Δtmγ=0∼2.2\Delta t_{m_\gamma=0}\sim 2.2 billion years.Comment: v3: consequences of an error in evolution equation for coupling rectified, only a minimal change in physics results, two refs. adde

    "Forbidden" transitions between quantum Hall and insulating phases in p-SiGe heterostructures

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    We show that in dilute metallic p-SiGe heterostructures, magnetic field can cause multiple quantum Hall-insulator-quantum Hall transitions. The insulating states are observed between quantum Hall states with filling factors \nu=1 and 2 and, for the first time, between \nu=2 and 3 and between \nu=4 and 6. The latter are in contradiction with the original global phase diagram for the quantum Hall effect. We suggest that the application of a (perpendicular) magnetic field induces insulating behavior in metallic p-SiGe heterostructures in the same way as in Si MOSFETs. This insulator is then in competition with, and interrupted by, integer quantum Hall states leading to the multiple re-entrant transitions. The phase diagram which accounts for these transition is similar to that previously obtained in Si MOSFETs thus confirming its universal character
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