811 research outputs found

    CMG2/ANTXR2 regulates extracellular collagen VI which accumulates in hyaline fibromatosis syndrome.

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    Loss-of-function mutations in capillary morphogenesis gene 2 (CMG2/ANTXR2), a transmembrane surface protein, cause hyaline fibromatosis syndrome (HFS), a severe genetic disorder that is characterized by large subcutaneous nodules, gingival hypertrophy and severe painful joint contracture. Here we show that CMG2 is an important regulator of collagen VI homoeostasis. CMG2 loss of function promotes accumulation of collagen VI in patients, leading in particular to nodule formation. Similarly, collagen VI accumulates massively in uteri of Antxr2 <sup>-/-</sup> mice, which do not display changes in collagen gene expression, and leads to progressive fibrosis and sterility. Crossing Antxr2 <sup>-/-</sup> with Col6a1 <sup>-/-</sup> mice leads to restoration of uterine structure and reversion of female infertility. We also demonstrate that CMG2 may act as a signalling receptor for collagen VI and mediates its intracellular degradation

    The role of chiral loops in ηπ0π0γγ\eta\to\pi^0\pi^0\gamma\gamma

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    We consider the rare decay ηπ0π0γγ\eta\to\pi^0\pi^0\gamma\gamma and calculate the non-resonant contribution to the amplitude to one loop in Chiral Perturbation Theory. We display our result as both a diphoton energy spectrum and a partial decay rate as a function of the photon energy cut. It turns out that the one-loop correction can be numerically very important and could be detected, at sufficiently large center-of-mass photon energies, from a measurement of the partial decay width.Comment: 10 pages, Latex. Discussion on the resonant background enlarged, sign error corrected, basic results unchanged. To appear in Phys. Lett.

    Virtual Compton Scattering off the Pseudoscalar Meson Octet

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    We present a calculation of the virtual Compton scattering amplitude for the pseudoscalar meson octet in the framework of chiral perturbation theory at O(p4){\cal O}(p^4). We calculate the electromagnetic generalized polarizabilities and compare the results in the real Compton scattering limit to available experimental values. Finally, we give predictions for the differential cross section of electron-meson bremsstrahlung.Comment: 9 pages, Latex, uses cjp3.sty (included), 4 eps figures, to be published in the proceedings of the 13th Indian-Summer School "Understanding the Structure of Hadrons," August 28 - September 1, 2000, Prague, Czech Republi

    Two-point function of strangeness-carrying vector-currents in two-loop Chiral Perturbation Theory

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    We calculate the correlator between two external vector-currents having the quantum-numbers of a charged kaon. We give the renormalized expression to two loops in standard chiral perturbation theory in the isospin limit, which, as a physical result, is finite and scale-independent. Applications include a low energy theorem, valid at two loop order, of a flavor breaking combination of vector current correlators as well as a determination of the phenomenologically relevant finite O(p6)O(p^6)-counterterm combination QVQ_V by means of inverse moment finite energy sum rules. This determination is less sensitive to isospin-breaking effects than previous attempts.Comment: 24 pages, revtex, 4 figures, 2 tables, revised version, one ref. adde

    Theory of oscillations in the STM conductance resulting from subsurface defects (Review Article)

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    In this review we present recent theoretical results concerning investigations of single subsurface defects by means of a scanning tunneling microscope (STM). These investigations are based on the effect of quantum interference between the electron partial waves that are directly transmitted through the contact and the partial waves scattered by the defect. In particular, we have shown the possibility imaging the defect position below a metal surface by means of STM. Different types of subsurface defects have been discussed: point-like magnetic and non-magnetic defects, magnetic clusters in a nonmagnetic host metal, and non-magnetic defects in a s-wave superconductor. The effect of Fermi surface anisotropy has been analyzed. Also, results of investigations of the effect of a strong magnetic field to the STM conductance of a tunnel point contact in the presence of a single defect has been presented.Comment: 31 pages, 10 figuers Submitted to Low. Temp. Phy

    Lifetimes of electrons in the Shockley surface state band of Ag(111)

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    We present a theoretical many-body analysis of the electron-electron (e-e) inelastic damping rate Γ\Gamma of electron-like excitations in the Shockley surface state band of Ag(111). It takes into account ab-initio band structures for both bulk and surface states. Γ\Gamma is found to increase more rapidly as a function of surface state energy E than previously reported, thus leading to an improved agreement with experimental data

    The effects of excluding patients from the analysis in randomised controlled trials: meta-epidemiological study

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    Objective To examine whether excluding patients from the analysis of randomised trials are associated with biased estimates of treatment effects and higher heterogeneity between trials

    Effect of multidimensional lifestyle intervention on fitness and adiposity in predominantly migrant preschool children (Ballabeina): cluster randomised controlled trial

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    Objective To test the effect of a multidimensional lifestyle intervention on aerobic fitness and adiposity in predominantly migrant preschool children
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