Intersecting Loop Models on Z^D: Rigorous Results

We consider a general class of (intersecting) loop models in D dimensions, including those related to high-temperature expansions of well-known spin models. We find that the loop models exhibit some interesting features - often in the ``unphysical'' region of parameter space where all connection with the original spin Hamiltonian is apparently lost. For a particular n=2, D=2 model, we establish the existence of a phase transition, possibly associated with divergent loops. However, for n >> 1 and arbitrary D there is no phase transition marked by the appearance of large loops. Furthermore, at least for D=2 (and n large) we find a phase transition characterised by broken translational symmetry.Comment: LaTeX+elsart.cls; 30 p., 6 figs; submitted to Nucl. Phys. B; a few minor typos correcte

Two phase transitions in the fully frustrated XYXY model

The fully frustrated $XY$ model on a square lattice is studied by means of Monte Carlo simulations. A Kosterlitz-Thouless transition is found at $T_{\rm KT} \approx 0.446$, followed by an ordinary Ising transition at a slightly higher temperature, $T_c \approx 0.452$. The non-Ising exponents reported by others, are explained as a failure of finite size scaling due to the screening length associated with the nearby Kosterlitz-Thouless transition.Comment: REVTEX file, 8 pages, 5 figures in uuencoded postscrip

Анализ эффективности процессов планирования электроснабжения в Харьковском регионе

Ефективність процесів електропостачання запропоновано оцінювати не тільки величиною помилки прогнозування, а й кількістю негативних і позитивних помилок, що вимірюються за методикою Тейла. Виконано аналіз планованих і фактичних добових обсягів електроспоживання в Харківському регіоні в 2008 і 2009 роках. Оцінено помилки переоцінки і недооцінки фактичних обсягів, обчислені складові загальної помилки і показано, що переважає помилка неповної коваріації прогнозованих і фактичних значень добових обсягів ринку споживачів АК "Харківобленерго".The effectiveness of the processes of electricity supply was offered to assess not only with the magnitude of forecasting error, but with the number of negative and positive errors, measured by the method of Theil. The analysis of planned and actual daily volume of electricity in Kharkov region in 2008 and 2009 is realized. Errors of revaluation and underestimation of actual volumes are estimated, components of the general error are calculated and shown that the error of incomplete covariance for predicted and actual values of daily volumes of the market of consumers АК of "Kharkovo-blenergo" prevails

Evidence for Complex Subleading Exponents from the High-Temperature Expansion of the Hierarchical Ising Model

Using a renormalization group method, we calculate 800 high-temperature coefficients of the magnetic susceptibility of the hierarchical Ising model. The conventional quantities obtained from differences of ratios of coefficients show unexpected smooth oscillations with a period growing logarithmically and can be fitted assuming corrections to the scaling laws with complex exponents.Comment: 10 pages, Latex , uses revtex. 2 figures not included (hard copies available on request

Superconductor-to-Spin-Density-Wave Transition in Quasi-One-Dimensional Metals with Ising Anisotropy

We study a mechanism for superconductivity in quasi-one-dimensional materials with Ising anisotropy. In an isolated chain Ising anisotropy opens a spin gap; if inter-chain coupling is sufficiently weak, single particle hopping is suppressed and the physics of coupled chains is controlled by a competition between pair hopping and exchange interaction. Spin density wave and triplet superconductivity phases are found separated by a first order phase transition. For particular parameter values a second order transition described by SO(4) symmetry is found.Comment: 18 pages, 1 figur

Electro-anatomical mapping of the left atrium before and after cryothermal balloon isolation of the pulmonary veins

Introduction: The 28 mm cryoballoon catheter is a device used for pulmonary vein isolation (PVI). The aim of this study was to evaluate the extent of the ablation in the antral regions of the left atrium. Methods and Results: Eighteen patients with drug refractory, symptomatic, paroxysmal AF were enrolled. A 3D electroanatomic reconstruction of the left atrium was made before and after successful PVI with the 28 mm cryoballoon. Markers were placed at the ostium. Sixteen patients were mapped. Fourteen patients had 4 veins each, and 2 patients had a common ostium of the left sided veins. All separate ostia were isolated in the antral region. The two common ostia showed ostial isolation. There was a significant difference in vein size between the common (29 and 31 mm) and the separate ostia (19∈±∈4 mm) (p∈<∈0.01). The performance of an additional segmental ablation if balloon PVI did not eliminate all electrical activity, did not influence the extent of the ablation. The earliest left atrial activation during sinus rhythm was located in the superior septal region before ablation in all patients. After ablation, two patients showed a substantial downward shift towards the middle and inferior septal region respectively (NS). Four patients demonstrated a slight downward shift of the first activation. Conclusions: In cryoballoon PVI, the majority of the veins undergo antral isolation. Veins with a diameter larger than the balloon, are isolated ostially. In individual cases, the left atrial activation sequence appears to be altered after ablation

Monte Carlo simulation of ice models

We propose a number of Monte Carlo algorithms for the simulation of ice models and compare their efficiency. One of them, a cluster algorithm for the equivalent three colour model, appears to have a dynamic exponent close to zero, making it particularly useful for simulations of critical ice models. We have performed extensive simulations using our algorithms to determine a number of critical exponents for the square ice and F models.Comment: 32 pages including 15 postscript figures, typeset in LaTeX2e using the Elsevier macro package elsart.cl

Roughening Induced Deconstruction in (100) Facets of CsCl Type Crystals

The staggered 6-vertex model describes the competition between surface roughening and reconstruction in (100) facets of CsCl type crystals. Its phase diagram does not have the expected generic structure, due to the presence of a fully-packed loop-gas line. We prove that the reconstruction and roughening transitions cannot cross nor merge with this loop-gas line if these degrees of freedom interact weakly. However, our numerical finite size scaling analysis shows that the two critical lines merge along the loop-gas line, with strong coupling scaling properties. The central charge is much larger than 1.5 and roughening takes place at a surface roughness much larger than the conventional universal value. It seems that additional fluctuations become critical simultaneously.Comment: 31 pages, 9 figure

Dynamic renormalization group study of a generalized continuum model of crystalline surfaces

We apply the Nozieres-Gallet dynamic renormalization group (RG) scheme to a continuum equilibrium model of a d-dimensional surface relaxing by linear surface tension and linear surface diffusion, and which is subject to a lattice potential favoring discrete values of the height variable. The model thus interpolates between the overdamped sine-Gordon model and a related continuum model of crystalline tensionless surfaces. The RG flow predicts the existence of an equilibrium roughening transition only for d = 2 dimensional surfaces, between a flat low-temperature phase and a rough high-temperature phase in the Edwards-Wilkinson (EW) universality class. The surface is always in the flat phase for any other substrate dimensions d > 2. For any value of d, the linear surface diffusion mechanism is an irrelevant perturbation of the linear surface tension mechanism, but may induce long crossovers within which the scaling properties of the linear molecular-beam epitaxy equation are observed, thus increasing the value of the sine-Gordon roughening temperature. This phenomenon originates in the non-linear lattice potential, and is seen to occur even in the absence of a bare surface tension term. An important consequence of this is that a crystalline tensionless surface is asymptotically described at high temperatures by the EW universality class.Comment: 22 pages, 5 figures. Accepted for publication in Physical Review

Prospective blinded evaluation of a novel sensing methodology designed to reduce inappropriate shocks by the subcutaneous implantable cardioverter-defibrillator

Background: Most inappropriate shocks from the subcutaneous implantable cardioverter-defibrillator (S-ICD) are caused by cardiac oversensing. A novel sensing methodology, SMART Pass (SP; Boston Scientific Corporation, Natick, MA), aims to reduce cardiac oversensing. Objective: The purpose of this study was to evaluate the effect of SP on shocks in ambulatory patients with S-ICD. Methods: Patients implanted in 2015–2016 and enrolled in a remote patient monitoring system were included and followed for 1 year. Shocks were adjudicated by 3 independent blinded reviewers as appropriate or inappropriate. Shock incidence was calculated for patients with SP programmed enabled or disabled at implantation, censoring patients when SP programming changed or at the last transmission. The SP setting (enabled vs disabled) was modeled as a time-dependent Cox regression variable. Results: The cohort consisted of 1984 patients, and a total of 880 shocks were adjudicated. At implantation, SP was enabled in 655 patients (33%) and disabled in 1329 patients (67%). SP reduced the risk for the first inappropriate shock by 50% (P <.001) and the risk for all inappropriate shocks by 68% (P <.001) in multivariate analysis adjusted for age and device programming. The incidence of inappropriate shocks was 4.3% in the SP enabled arm vs 9.7% in the SP disabled arm. The incidence of appropriate shocks was similar (5.2