Stochastic field evolution of disoriented chiral condensates

I present a summary of recent work \cite{BRS} where we describe the time-evolution of a region of disoriented chiral condensate via Langevin field equations for the linear $\sigma$ model. We analyze the model in equilibrium, paying attention to subtracting ultraviolet divergent classical terms and replacing them by their finite quantum counterparts. We use results from lattice gauge theory and chiral perturbation theory to fix nonuniversal constants. The result is a ultraviolet cutoff independent theory that reproduces quantitatively the expected equilibrium behavior of pion and $\sigma$ quantum fields. We also estimate the viscosity $\eta(T)$, which controls the dynamical timescale in the Langevin equation, so that the near equilibrium dynamical response agrees with theoretical expectations.Comment: 3 pages, 3 figures, contribution to the proceedings of Lattice0

Temperature Dependence of Electric and Magnetic Gluon Condensates

The contribution of Lorentz non-scalar operators to finite temperature correlation functions is discussed. Using the local duality approach for the one-pion matrix element of a product of two vector currents, the temperature dependence of the average gluonic stress tensor is estimated in the chiral limit to be $\langle{\bf E}^2 +{\bf B}^2\rangle_{T}=\frac{\pi^2}{10}bT^4$. At a normalization point $\mu=0.5$ GeV we obtain $b\approx 1.1$. Together with the known temperature dependence of the Lorentz scalar gluon condensate we are able to infer $\langle{\bf E}^2\rangle_T$ and $\langle{\bf B}^2\rangle_T$ separately in the low-temperature hadronic phase.Comment: 11 pages, TPI-MINN-92/37-

Understanding the Burden of Atopic Dermatitis in Africa and the Middle East

Atopic dermatitis (AD) is a common inflammatory skin disease characterized by intensely pruritic lesions. The prevalence of atopic dermatitis is increasing in developing regions, including Africa and the Middle East. However, these regions are underrepresented in the dermatology literature, and a better understanding of the growing burden of atopic dermatitis in Africa and the Middle East is necessary. Herein, we summarize current knowledge on atopic dermatitis epidemiology, disease burden, and treatment options in Africa and the Middle East, highlighting the unmet needs of patients in these regions. With these needs in mind, we provide clinical recommendations for appropriate management of atopic dermatitis in Africa and the Middle East. Funding: Pfizer Inc. Plain Language Summary: Plain language summary available for this article.Editorial/medical writing support under the guidance of the authors was provided by Madeline L. Pfau, PhD, and Corey Mandel, PhD, at ApotheCom, New York, NY, and San Francisco, CA, USA, and was funded by Pfizer Inc., New York, NY, USA, in accordance with Good Publication Practice (GPP3) guidelines ( Ann Intern Med. 2015;163:461-464).Scopu

Thermal modelling of low concentrator photovoltaic systems

Efficient thermal management of low concentrator photovoltaic (LCPV) systems will allow maximizing of the power output and may also substantially prolong operating lifetime. For this reason, it is necessary to develop a thorough understanding of the thermal transfer and dissipation mechanisms associated with an LCPV system. The LCPV system under consideration uses a 7-facet reflector optical design, providing a geometric concentration ratio of approximately 4.85. The LCPV system succeeded in increasing the short circuit current from 1A to 5.6A, demonstrating an effective concentration ratio of approximately 4.75. LCPV system temperatures in excess of 80°C were recorded without a thermal management system. A basic thermal model was developed and assessed under various environmental conditions. The effectiveness of a heat-sink, which reduced the temperature difference between the LCPV receiver temperature and the ambient temperature by 37.5%, was also evaluated. The results discussed in this paper will assist the future development of techniques aimed at reducing the high temperatures associated with LCPV systems

Lehr- und lernrelevante Diversität an der Fachhochschule Köln

Studierende der Fachhochschule Köln unterscheiden sich in zunehmendem Maße in ihren sozio-kulturellen, bildungsbiografischen und kognitiven Voraussetzungen für einen hochschulischen Bildungsprozess. Lehre zeigt sich vor dem Hintergrund dieser Diversität zunehmend als Herausforderung. Ausgehend vom Ziel, studentisches Lern- und Arbeitsverhalten verstärkt auf Studienerfolg und die Gestaltung von Lehrveranstaltungen auf heterogene Zielgruppen auszurichten, wurde die Studie „Diversity Forschung“ durchgeführt, um Status quo der und Gestaltungsspielräume für Diversity-bezogene Aufmerksamkeit und Verständnis für lehr- und lernrelevante Effekte zu identifizieren. Die Studie wurde mit dem Forschungstypus Innerinstitutionelle Hochschulforschung durchgeführt. Was kann und was sollte eine Hochschule über ihr Kerngeschäft Studium und Lehre wissen, wie kommt sie zu diesem Wissen und was fängt sie damit an? Innerinstitutionelle Hochschulforschung macht Handlungen und Prozesse im Rahmen von Studium und Lehre in den Strukturen der Hochschule transparent und kann so die institutionelle Selbstaufklärung und das Qualitätsmanagement stützen. Gegenstand dieses Berichts sind Ansatz, Methoden und Befunde innerinstitutioneller hochschuldidaktischer Forschung an der Fachhochschule Köln. Schwerpunkt ist die Diversität der Lehrenden und Lernenden als Akteursgruppen und -gemeinschaft in Sachen Studium und Lehre. Ausgangspunkt war die Absicht, den Status lehr- und lernrelevanter Diversität zu erkennen, Gestaltungsspielräume für den Umgang mit Diversität auszuloten und Implementationen innovativer Lehrkonzepte für erfolgreiches Studieren mit einem Monitoring-Ansatz zu begleiten. Weiterer Gegenstand des Berichts sind die Einflüsse dieser Forschung als Selbstbeobachtung auf intendierte Change-Prozesse zur Verbesserung von Studium und Lehre und die Frage, wie Selbstbeobachtungsstrategien als hochschuldidaktische Hochschulforschung weiter elaboriert werden und deren Befunde in die hochschuldidaktische Praxis und die Lehr- und Lernkultur der Fachhochschule Köln gelangen können

Endovascular Treatment for Acute Isolated Internal Carotid Artery Occlusion : A Propensity Score Matched Multicenter Study.

The benefit of endovascular treatment (EVT) in patients with acute symptomatic isolated occlusion of the internal carotid artery (ICA) without involvement of the middle and anterior cerebral arteries is unclear. We aimed to compare clinical and safety outcomes of best medical treatment (BMT) versus EVT + BMT in patients with stroke due to isolated ICA occlusion. We conducted a retrospective multicenter study involving patients with isolated ICA occlusion between January 2016 and December 2020. We stratified patients by BMT versus EVT and matched the groups using propensity score matching (PSM). We assessed the effect of treatment strategy on favorable outcome (modified Rankin scale ≤ 2) 90 days after treatment and compared reduction in NIHSS score at discharge, rates of symptomatic intracranial hemorrhage (sICH) and 3‑month mortality. In total, we included 149 patients with isolated ICA occlusion. To address imbalances, we matched 45 patients from each group using PSM. The rate of favorable outcomes at 90 days was 56% for EVT and 38% for BMT (odds ratio, OR 1.89, 95% confidence interval, CI 0.84-4.24; p = 0.12). Patients treated with EVT showed a median reduction in NIHSS score at discharge of 6 points compared to 1 point for BMT patients (p = 0.02). Rates of symptomatic intracranial hemorrhage (7% vs. 4%; p = 0.66) and 3‑month mortality (11% vs. 13%; p = 0.74) did not differ between treatment groups. Periprocedural complications of EVT with early neurological deterioration occurred in 7% of cases. Although the benefit on functional outcome did not reach statistical significance, the results for NIHSS score improvement, and safety support the use of EVT in patients with stroke due to isolated ICA occlusion

Langevin Evolution of Disoriented Chiral Condensate

As the matter produced in a relativistic heavy ion collision cools through the QCD phase transition, the dynamical evolution of the chiral condensate will be driven out of thermal equilibrium. As a prelude to analyzing this evolution, and in particular as a prelude to learning how rapid the cooling must be in order for significant deviations from equilibrium to develop, we present a detailed analysis of the time-evolution of an idealized region of disoriented chiral condensate. We set up a Langevin field equation which can describe the evolution of these (or more realistic) linear sigma model configurations in contact with a heat bath representing the presence of other shorter wavelength degrees of freedom. We first analyze the model in equilibrium, paying particular attention to subtracting ultraviolet divergent classical terms and replacing them by their finite quantum counterparts. We use known results from lattice gauge theory and chiral perturbation theory to fix nonuniversal constants. The result is a theory which is ultraviolet cutoff independent and that reproduces quantitatively the expected equilibrium behavior of the quantum field theory of pions and sigma fields over a wide range of temperatures. Finally, we estimate the viscosity $\eta(T)$, which controls the dynamical timescale in the Langevin equation, by requiring that the timescale for DCC decay agrees with previous calculations. The resulting $\eta(T)$ is larger than that found perturbatively. We also determine the temperature below which the classical field Langevin equation ceases to be a good model for the quantum field dynamics.Comment: 19 pages, 7 figures, uses RevTex; v2 very small change to the caption of Fig.7. Version to appear in Nucl. phys.

Leptonic Decay Constants of DsD_{s} and BsB_{s} Mesons at Finite Temperature

In the present work, $D_{s}$ and $B_{s}$ meson parameters are investigated in the framework of thermal QCD sum rules. The temperature dependence of the mass and the leptonic decay constants are investigated by using Borel transform sum rules and Hilbert moment sum rules. To increase sensitivity, the vacuum contributions are subtracted from thermal expressions and the temperature dependences of the leptonic decay constants and meson masses are studied.Comment: 9 pages, 1 table, 4 figure

Chiral symmetry breaking in hot matter

This series of three lectures covers (a) a basic introduction to symmetry breaking in general and chiral symmetry breaking in QCD, (b) an overview of the present status of lattice data and the knowlegde that we have at finite temperature from chiral perturbation theory. (c) Results obtained from the Nambu--Jona-Lasinio model describing static mesonic properties are discussed as well as the bulk thermodynamic quantities. Divergences that are observed in the elastic quark-antiquark scattering cross-section, reminiscent of the phenomenon of critical opalescence in light scattering, is also discussed. (d) Finally, we deal with the realm of systems out of equilibrium, and examine the effects of a medium dependent condensate in a system of interacting quarks.Comment: 62 LaTex pages, incorporating 23 figures. Lectures given at the eleventh Chris-Engelbrecht Summer School in Theoretical Physics, 4-13 February, 1998, to be published by Springer Verla

Formation of extended topological defects during symmetry breaking phase transitions in O(2) and O(3) models

The density of extended topological defects created during symmetry-breaking phase transitions depends on the ratio between the correlation length in the symmetric phase near $T_c$ and the winding length of the defects as determined by the momentaneous effective action after a typical relaxation time. Conservation of winding number in numerical simulations requires a suitable embedding of the field variables and the appropriate geometrical implementation of the winding density on the discrete lattice. We define a modified Kibble limit for the square lattice and obtain defect densities as functions of winding lengths in O(2) and O(3) models. The latter allows to observe formation of disoriented aligned domains within the easy plane. Their extent is severely limited by the momentaneous defect density during the course of the quench.Comment: 16 pages, 9 figure