Revising consensus in portal hypertension

Portal hypertension is associated with the most severe complications of cirrhosis, including ascites, hepatic encephalopathy, and bleeding from gastro-esophageal varices. Despite the progress achieved over the last decades, the 6-week mortality associated with variceal bleeding is still in the order of 10–20%. Awareness of the difficulty inherent to the evaluation of diagnostic tools and the design and conduct of good clinical trials for the treatment of portalhypertensionhas led to theorganization, since1986,of a series of consensus meetings. The first one was organized by Andrew Burroughs in Groningen, The Netherlands [1]. After Groningen, other meetings followed, in Baveno in 1990 (Baveno I) [2] and in 1995 (Baveno II) [3,4], in Milan in 1992 [5], in Reston, USA, in 1996 [6], in Stresa in 2000 (Baveno III) [7,8], again in Baveno in 2005 (Baveno IV) [9,10], and in Atlanta in 2007 [11]. The aims of these meetings were to develop definitions of key events in portal hypertension and variceal bleeding, to review the existing evidence on the natural history, the diagnosis and the therapeutic modalities of portal hypertension, and to issue evidence-based recommendations for the conduct of clinical trials and the management of patients. All these meetings were successful and produced consensus statements on some important points, although some issues remained unsettled. To continue the work of the previous meetings, a Baveno V workshop was held on May 21–22, 2010. The workshop was attended by many of the experts responsible for most of the major achievements of the last years in this field. Many of them had attended the previous meetings as well. The main fields of discussion of the Baveno V workshop were the same as in Baveno I–IV, i.e. the definitions of key events concerning the bleeding episode and the therapeutic options in patients with portal hypertension. For each of these topics, a series of consensus statements were discussed and agreed upon. As in Baveno IV, whenever applicable, the level of existing evidence was evaluated and the recommendations were ranked according to the Oxford System [12] (i.e.: level of evidence from 1 = highes

Quasi-Particle Spectra, Charge-Density-Wave, Superconductivity and Electron-Phonon Coupling in 2H-NbSe2

High-resolution photoemission has been used to study the electronic structure of the charge density wave (CDW) and superconducting (SC) dichalcogenide, 2H- NbSe2. From the extracted self-energies, important components of the quasiparticle (QP) interactions have been identified. In contrast to previously studied TaSe2, the CDW transition does not affect the electronic properties significantly. The electron-phonon coupling is identified as a dominant contribution to the QP self-energy and is shown to be very anisotropic (k-dependent) and much stronger than in TaSe2.Comment: 4 pages, 3 figures, minor changes, to appear in PR

Doping of a One-Dimensional Mott Insulator: Photoemision and Optical Studies of Sr2_2CuO3+δ_{3+\delta}

The spectral properties of a one-dimensional (1D) single-chain Mott insulator Sr$_2$CuO$_{3}$ have been studied in angle-resolved photoemission and optical spectroscopy, at half filling and with small concentrations of extra charge doped into the chains via high oxygen pressure growth. The single- particle gap is reduced with oxygen doping, but the metallic state is not reached. The bandwidth of the charge-transfer band increases with doping, while the state becomes narrower, allowing unambiguous observation of separated spinon and holon branches in the doped system. The optical gap is not changed upon doping, indicating that a shift of chemical potential rather than decrease of corelation gap is responsible for the apparent reduction of the photoemission gap.Comment: 4 pages, 2 figure

Quasiparticle Interference on the Surface of Topological Crystalline Insulator Pb(1-x)Sn(x)Se

Topological crystalline insulators represent a novel topological phase of matter in which the surface states are protected by discrete point group-symmetries of the underlying lattice. Rock-salt lead-tin-selenide alloy is one possible realization of this phase which undergoes a topological phase transition upon changing the lead content. We used scanning tunneling microscopy (STM) and angle resolved photoemission spectroscopy (ARPES) to probe the surface states on (001) Pb$_{1-x}$Sn$_{x}$Se in the topologically non-trivial (x=0.23) and topologically trivial (x=0) phases. We observed quasiparticle interference with STM on the surface of the topological crystalline insulator and demonstrated that the measured interference can be understood from ARPES studies and a simple band structure model. Furthermore, our findings support the fact that Pb$_{0.77}$Sn$_{0.23}$Se and PbSe have different topological nature.Comment: 5 pages, 4 figure