The Weakly Coupled Gross-Neveu Model with Wilson Fermions

The nature of the phase transition in the lattice Gross-Neveu model with Wilson fermions is investigated using a new analytical technique. This involves a new type of weak coupling expansion which focuses on the partition function zeroes of the model. Its application to the single flavour Gross-Neveu model yields a phase diagram whose structure is consistent with that predicted from a saddle point approach. The existence of an Aoki phase is confirmed and its width in the weakly coupled region is determined. Parity, rather than chiral symmetry breaking naturally emerges as the driving mechanism for the phase transition.Comment: 15 pages including 1 figur

Foot burns: A comparative analysis of diabetic and non-diabetic patients

Introduction: Foot burns represent a small part of the body with many challenges. The impact of diabetes on clinical outcomes adds further issues in management that clinicians must consider in their management. These factors have serious implications on morbidity and long term sequelae. Our aim is to analyse epidemiological trends of foot burns and examine the differences between diabetic and non-diabetics at Concord hospital from 2014 to 2019. Methods: A retrospective audit from 2014–19 at Concord General Repatriation Hospital Burns Unit summarised patient demographics, burn injury, diabetic status, operations and length of stay. All foot burn injuries from 2014–19 of all ages and gender that attended Concord burns hospital were included in this study. Results: We treated 797 patients who presented with foot burns, of which 16.2% were diabetic. The average age was higher in diabetics (60.72 years) than non-diabetics (39.72 years) and more males suffered burns compared to females in both groups (p \u3c 0.001). There was a larger portion of elderly patients (greater than 65 years old, 15.1% of total) who sustained foot burns in the diabetic group compared to the non-diabetic group (p \u3c 0.001). The most affected season was summer (27.0%), but diabetic patients were 1.7 times more likely to sustain injury in winter than non-diabetics. Diabetics were 3.8 times more likely to have contact burns compared to non-diabetic patients (p \u3c 0.001). In a multivariable linear regression analysis, factors that contributed to increased length of stay included elderly status, place of event, diabetic status, number of operations, ICU admission, wound infection, amputation, and admission [F (16, 757 = 41.149, p \u3c 0.001, R2 = 0.465]. Conclusions: With the increase of diabetes, our multidisciplinary approach to diabetic foot care should include nursing, medical and surgical disciplines to identify patients at risk. The data highlights that a focus on prevention and education for diabetes is central to optimize glycaemic control and burn management, whilst providing a multidisciplinary network on discharge

Numerical study of duality and universality in a frozen superconductor

The three-dimensional integer-valued lattice gauge theory, which is also known as a "frozen superconductor," can be obtained as a certain limit of the Ginzburg-Landau theory of superconductivity, and is believed to be in the same universality class. It is also exactly dual to the three-dimensional XY model. We use this duality to demonstrate the practicality of recently developed methods for studying topological defects, and investigate the critical behavior of the phase transition using numerical Monte Carlo simulations of both theories. On the gauge theory side, we concentrate on the vortex tension and the penetration depth, which map onto the correlation lengths of the order parameter and the Noether current in the XY model, respectively. We show how these quantities behave near the critical point, and that the penetration depth exhibits critical scaling only very close to the transition point. This may explain the failure of superconductor experiments to see the inverted XY model scaling.Comment: 17 pages, 18 figures. Updated to match the version published in PRB (http://link.aps.org/abstract/PRB/v67/e014525) on 27 Jan 200

Properties of the Bose glass phase in irradiated superconductors near the matching field

Structural and transport properties of interacting localized flux lines in the Bose glass phase of irradiated superconductors are studied by means of Monte Carlo simulations near the matching field B_Phi, where the densities of vortices and columnar defects are equal. For a completely random columnar pin distribution in the xy-plane transverse to the magnetic field, our results show that the repulsive vortex interactions destroy the Mott insulator phase which was predicted to occur at B = B_Phi. On the other hand, for ratios of the penetration depth to average defect distance lambda/d <= 1, characteristic remnants of the Mott insulator singularities remain visible in experimentally accessible quantities as the magnetization, the bulk modulus, and the magnetization relaxation, when B is varied near B_Phi. For spatially more regular disorder, e.g., a nearly triangular defect distribution, we find that the Mott insulator phase can survive up to considerably large interaction range \lambda/d, and may thus be observable in experiments.Comment: RevTex, 17 pages, eps files for 12 figures include

Random Mass Dirac Fermions in Doped Spin-Peierls and Spin-Ladder systems: One-Particle Properties and Boundary Effects

Quasi-one-dimensional spin-Peierls and spin-ladder systems are characterized by a gap in the spin-excitation spectrum, which can be modeled at low energies by that of Dirac fermions with a mass. In the presence of disorder these systems can still be described by a Dirac fermion model, but with a random mass. Some peculiar properties, like the Dyson singularity in the density of states, are well known and attributed to creation of low-energy states due to the disorder. We take one step further and study single-particle correlations by means of Berezinskii's diagram technique. We find that, at low energy $\epsilon$, the single-particle Green function decays in real space like $G(x,\epsilon) \propto (1/x)^{3/2}$. It follows that at these energies the correlations in the disordered system are strong -- even stronger than in the pure system without the gap. Additionally, we study the effects of boundaries on the local density of states. We find that the latter is logarithmically (in the energy) enhanced close to the boundary. This enhancement decays into the bulk as $1/\sqrt{x}$ and the density of states saturates to its bulk value on the scale $L_\epsilon \propto \ln^2 (1/\epsilon)$. This scale is different from the Thouless localization length $\lambda_\epsilon\propto\ln (1/\epsilon)$. We also discuss some implications of these results for the spin systems and their relation to the investigations based on real-space renormalization group approach.Comment: 26 pages, LaTex, 9 PS figures include

The types of Mott insulator

There are two classes of Mott insulators in nature, distinguished by their responses to weak doping. With increasing chemical potential, Type I Mott insulators undergo a first order phase transition from the undoped to the doped phase. In the presence of long-range Coulomb interactions, this leads to an inhomogeneous state exhibiting ``micro-phase separation.'' In contrast, in Type II Mott insulators charges go in continuously above a critical chemical potential. We show that if the insulating state has a broken symmetry, this increases the likelihood that it will be Type I. There exists a close analogy between these two types of Mott insulators and the familiar Type I and Type II superconductors

Large Scale Structure Formation with Global Topological Defects. A new Formalism and its implementation by numerical simulations

We investigate cosmological structure formation seeded by topological defects which may form during a phase transition in the early universe. First we derive a partially new, local and gauge invariant system of perturbation equations to treat microwave background and dark matter fluctuations induced by topological defects or any other type of seeds. We then show that this system is well suited for numerical analysis of structure formation by applying it to seeds induced by fluctuations of a global scalar field. Our numerical results are complementary to previous investigations since we use substantially different methods. The resulting microwave background fluctuations are compatible with older simulations. We also obtain a scale invariant spectrum of fluctuations with about the same amplitude. However, our dark matter results yield a smaller bias parameter compatible with $b\sim 2$ on a scale of $20 Mpc$ in contrast to previous work which yielded to large bias factors. Our conclusions are thus more positive. According to the aspects analyzed in this work, global topological defect induced fluctuations yield viable scenarios of structure formation and do better than standard CDM on large scales.Comment: uuencoded, compressed tar-file containing the text in LaTeX and 12 Postscript Figures, 41 page

We Want to Know: Eliciting Hospitalized Patients' Perspectives on Breakdowns in Care

BACKGROUND: There is increasing recognition that patients have critical insights into care experiences, including breakdowns in care. Harnessing patient perspectives for hospital improvement requires an in-depth understanding of the types of breakdowns patients identify and the impact of these events. METHODS: We interviewed a broad sample of patients during hospitalization and post discharge to elicit patient perspectives on breakdowns in care. Through an iterative process, we developed a categorization of patient-perceived breakdowns called the Patient Experience Coding Tool. RESULTS: Of 979 interviewees, 386 (39.4%) believed they had experienced at least one breakdown in care. The most common reported breakdowns involved information exchange (n = 158, 16.1%), medications (n = 120, 12.3%), delays in admission (n = 90, 9.2%), team communication (n = 65, 6.6%), providers’ manner (n = 62, 6.3%), and discharge (n = 56, 5.7%). Of the 386 interviewees who reported a breakdown, 140 (36.3%) perceived associated harm. Patient-perceived harms included physical (eg, pain), emotional (eg, distress, worry), damage to relationship with providers, need for additional care or prolonged hospital stay, and life disruption. We found higher rates of reporting breakdowns among younger (<60 years old) patients (45.4% vs 34.5%, P < 0.001), those with at least some college education (46.8% vs 32.7%, P < 0.001), and those with another person (family or friend) present during the interview or interviewed in lieu of the patient (53.4% vs 37.8%, P = 0.002). CONCLUSIONS: When asked directly, almost 4 out of 10 hospitalized patients reported a breakdown in their care. Patient-perceived breakdowns in care are frequently associated with perceived harm, illustrating the importance of detecting and addressing these events. Journal of Hospital Medicine 2017;12:603-609. © 2017 Society of Hospital Medicin

Scaling critical behavior of superconductors at zero magnetic field

We consider the scaling behavior in the critical domain of superconductors at zero external magnetic field. The first part of the paper is concerned with the Ginzburg-Landau model in the zero magnetic field Meissner phase. We discuss the scaling behavior of the superfluid density and we give an alternative proof of Josephson's relation for a charged superfluid. This proof is obtained as a consequence of an exact renormalization group equation for the photon mass. We obtain Josephson's relation directly in the form $\rho_{s}\sim t^{\nu}$, that is, we do not need to assume that the hyperscaling relation holds. Next, we give an interpretation of a recent experiment performed in thin films of $YBa_{2}Cu_{3}O_{7-\delta}$. We argue that the measured mean field like behavior of the penetration depth exponent $\nu'$ is possibly associated with a non-trivial critical behavior and we predict the exponents $\nu=1$ and $\alpha=-1$ for the correlation lenght and specific heat, respectively. In the second part of the paper we discuss the scaling behavior in the continuum dual Ginzburg-Landau model. After reviewing lattice duality in the Ginzburg-Landau model, we discuss the continuum dual version by considering a family of scalings characterized by a parameter $\zeta$ introduced such that $m_{h,0}^2\sim t^{\zeta}$, where $m_{h,0}$ is the bare mass of the magnetic induction field. We discuss the difficulties in identifying the renormalized magnetic induction mass with the photon mass. We show that the only way to have a critical regime with $\nu'=\nu\approx 2/3$ is having $\zeta\approx 4/3$, that is, with $m_{h,0}$ having the scaling behavior of the renormalized photon mass.Comment: RevTex, 15 pages, no figures; the subsection III-C has been removed due to a mistak