A Selective Approach to Bleeding Esophageal Varices

It is possible that the best results of treatment for bleeding esophageal varices will come when a selective approach is used. In patients bleeding acutely and in patients with poor liver function shunt operations should be avoided, and a direct attack on the varices with either sclerosant therapy, percutaneous obliteration, or staple gun gastro-esophageal transsection should be carried out. In patients who have stopped bleeding, or those in whom elective treatment is being undertaken, the best operation at present appears to be selective distal splenorenal shunt

The Magnetic Properties of Selected Rare Earth Nitrides Grown by Pulsed Laser Deposition

Gadolinium nitride (GdN) and samarium nitride (SmN) are grown by pulsed laser deposition on yttria stabilised zirconia substrates. Surface and structural characterisation shows that the thin films are epitaxial with crystallites of up to 30 nm in diameter and a very large in plane coherence length. A novel oxide layer is observed at the substrate-film interface, caused by oxygen in the substrate reacting with the deposited rare earth element. GdN is found to be ferromagnetic below 70 K with a saturation moment of 7 Bohr magneton per ion. The relationship between the crystal structure and the magnetisation is investigated using ferromagnetic resonance and a weak easy axis along the [111] azimuth is reported. Hall effect measurements show the carriers are electrons, present in concentrations of 1020/cm3. Magnetic measurements on SmN show the presence of metallic droplets, but correcting for these, the Curie temperature is found to be 30 K.We report on preliminary growths of europium nitride and show the valence of the Eu is 3+, solving an outstanding theoretical question

Determining the Surface-To-Bulk Progression in the Normal-State Electronic Structure of Sr2RuO4 by Angle-Resolved Photoemission and Density Functional Theory

In search of the potential realization of novel normal-state phases on the surface of Sr2RuO4 - those stemming from either topological bulk properties or the interplay between spin-orbit coupling (SO) and the broken symmetry of the surface - we revisit the electronic structure of the top-most layers by ARPES with improved data quality as well as ab-initio LDA slab calculations. We find that the current model of a single surface layer (\surd2x\surd2)R45{\deg} reconstruction does not explain all detected features. The observed depth-dependent signal degradation, together with the close quantitative agreement with LDA+SO slab calculations based on the LEED-determined surface crystal structure, reveal that (at a minimum) the sub-surface layer also undergoes a similar although weaker reconstruction. This points to a surface-to-bulk progression of the electronic states driven by structural instabilities, with no evidence for Dirac and Rashba-type states or surface magnetism.Comment: 4 pages, 4 figures, 1 table. Further information and PDF available at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm

Na2IrO3 as a spin-orbit-assisted antiferromagnetic insulator with a 340 meV gap

We study Na2IrO3 by ARPES, optics, and band structure calculations in the local-density approximation (LDA). The weak dispersion of the Ir 5d-t2g manifold highlights the importance of structural distortions and spin-orbit coupling (SO) in driving the system closer to a Mott transition. We detect an insulating gap {\Delta}_gap = 340 meV which, at variance with a Slater-type description, is already open at 300 K and does not show significant temperature dependence even across T_N ~ 15 K. An LDA analysis with the inclusion of SO and Coulomb repulsion U reveals that, while the prodromes of an underlying insulating state are already found in LDA+SO, the correct gap magnitude can only be reproduced by LDA+SO+U, with U = 3 eV. This establishes Na2IrO3 as a novel type of Mott-like correlated insulator in which Coulomb and relativistic effects have to be treated on an equal footing.Comment: Accepted in Physical Review Letters. Auxiliary and related material can be found at: http://www.phas.ubc.ca/~quantmat/ARPES/PUBLICATIONS/articles.htm

Rashba spin-splitting control at the surface of the topological insulator Bi2Se3

The electronic structure of Bi2Se3 is studied by angle-resolved photoemission and density functional theory. We show that the instability of the surface electronic properties, observed even in ultra-high-vacuum conditions, can be overcome via in-situ potassium deposition. In addition to accurately setting the carrier concentration, new Rashba-like spin-polarized states are induced, with a tunable, reversible, and highly stable spin splitting. Ab-initio slab calculations reveal that these Rashba state are derived from the 5QL quantum-well states. While the K-induced potential gradient enhances the spin splitting, this might be already present for pristine surfaces due to the symmetry breaking of the vacuum-solid interface.Comment: A high-resolution version can be found at http://www.physics.ubc.ca/~quantmat/ARPES/PUBLICATIONS/Articles/BiSe_K.pd

Pharmacological characterization of the αvβ6 integrin binding and internalization kinetics of the foot-and-mouth disease virus derived peptide A20FMDV2

A20FMDV2 is a peptide derived from the foot-and-mouth disease virus with a high affinity and selectivity for the alphav beta-6 (αvβ6) arginyl-glycinyl-aspartic acid (RGD)-binding integrin. It has been shown to be an informative tool ligand in pre-clinical imaging studies for selective labelling of the αvβ6 integrin in a number of disease models. In a radioligand- binding assay using a radiolabelled form of the peptide ([3H]A20FMDV2), its high affinity (KD:0.22nmol/l) and selectivity (at least 85-fold) for αvβ6 over the other members of the RGD integrin family was confirmed. [3H]A20FMDV2 αvβ6 binding could be fully reversed only in the presence of EDTA, whereas a partial reversal was observed in the presence of excess concentrations of an RGD-mimetic small molecule (SC-68448) or unlabelled A20FMDV2. Using flow cytometry on bronchial epithelial cells, the ligand-induced internalization of αvβ6 by A20FMDV2 and LAP1 was shown to be fast (t1/2:1.5and 3.1 min, respectively), concentration-dependent (EC50:values 1.1 and 3.6nmol/l, respectively) and was followed by a moderately slow return of integrin to the surface. The results of the radioligand-binding studies suggest that the binding of A20FMDV2 to the RGD-binding site on αvβ6 is required to maintain its engagement with the hypothesised A20FMDV2 synergy site on the integrin. In addition, there is evidence from flow cytometric studies that the RGD-ligand engagement of αvβ6 post-internalization plays a role in delaying recycling of the integrin to the cell surface. This mechanism may act as a homeostatic control of membrane αvβ6 following RGD ligand engagement

TREC-Rio trial: a randomised controlled trial for rapid tranquillisation for agitated patients in emergency psychiatric rooms [ISRCTN44153243]

Agitated or violent patients constitute 10% of all emergency psychiatric treatment. Management guidelines, the preferred treatment of clinicians and clinical practice all differ. Systematic reviews show that all relevant studies are small and none are likely to have adequate power to show true differences between treatments. Worldwide, current treatment is not based on evidence from randomised trials. In Brazil, the combination haloperidol-promethazine is frequently used, but no studies involving this mix exist. TREC-Rio (Tranquilização Rápida-Ensaio Clínico [Translation: Rapid Tranquillisation-Clinical Trial]) will compare midazolam with haloperidol-promethazine mix for treatment of agitated patients in emergency psychiatric rooms of Rio de Janeiro, Brazil. TREC-Rio is a randomised, controlled, pragmatic and open study. Primary measure of outcome is tranquillisation at 20 minutes but effects on other measures of morbidity will also be assessed. TREC-Rio will involve the collaboration of as many health care professionals based in four psychiatric emergency rooms of Rio as possible. Because the design of this trial does not substantially complicate clinical management, and in several aspects simplifies it, the study can be large, and treatments used in everyday practice can be evaluated

A multivariate hierarchical Bayesian approach to measuring agreement in repeated measurement method comparison studies

Background. Assessing agreement in method comparison studies depends on two fundamentally important components; validity (the between method agreement) and reproducibility (the within method agreement). The Bland-Altman limits of agreement technique is one of the favoured approaches in medical literature for assessing between method validity. However, few researchers have adopted this approach for the assessment of both validity and reproducibility. This may be partly due to a lack of a flexible, easily implemented and readily available statistical machinery to analyse repeated measurement method comparison data. Methods. Adopting the Bland-Altman framework, but using Bayesian methods, we present this statistical machinery. Two multivariate hierarchical Bayesian models are advocated, one which assumes that the underlying values for subjects remain static (exchangeable replicates) and one which assumes that the underlying values can change between repeated measurements (non-exchangeable replicates). Results. We illustrate the salient advantages of these models using two separate datasets that have been previously analysed and presented; (i) assuming static underlying values analysed using both multivariate hierarchical Bayesian models, and (ii) assuming each subject's underlying value is continually changing quantity and analysed using the non-exchangeable replicate multivariate hierarchical Bayesian model. Conclusion. These easily implemented models allow for full parameter uncertainty, simultaneous method comparison, handle unbalanced or missing data, and provide estimates and credible regions for all the parameters of interest. Computer code for the analyses in also presented, provided in the freely available and currently cost free software package WinBUGS