Strongly interacting 2D electron systems: Evidence for enhanced 1D edge-channel coupling

We observe nearly vanishing Hall resistances for integer filling factors in a counterflow (CF) experiment on a density balanced 2D bilayer system. Filling factor dependent equilibration lengths demonstrate enhanced 1D coupling via edge-channels. Due to the narrow barrier the edge-modes of the two 2DEGs are in close proximity allowing for 1D excitonic correlations. Electron drag measurements confirm the observed quantum state selective coupling between the layers

Evaluating Frequency, Diagnostic Quality, and Cost of Lyme Borreliosis Testing in Germany: A Retrospective Model Analysis

Background. Data on the economic impact of Lyme borreliosis (LB) on European health care systems is scarce. This project focused on the epidemiology and costs for laboratory testing in LB patients in Germany. Materials and Methods. We performed a sentinel analysis of epidemiological and medicoeconomic data for 2007 and 2008. Data was provided by a German statutory health insurance (DAK) company covering approx. 6.04 million members. In addition, the quality of diagnostic testing for LB in Germany was studied. Results. In 2007 and 2008, the incident diagnosis LB was coded on average for 15,742 out of 6.04 million insured members (0.26%). 20,986 EIAs and 12,558 immunoblots were ordered annually for these patients. For all insured members in the outpatient sector, a total of 174,820 EIAs and 52,280 immunoblots were reimbursed annually to health care providers (cost: 2,600,850€). For Germany, the overall expected cost is estimated at 51,215,105€. However, proficiency testing data questioned test quality and standardization of diagnostic assays used. Conclusion. Findings from this study suggest ongoing issues related to care for LB and may help to improve future LB disease management

Donor implanted back-gates in GaAs for MBE-grown highest mobility two-dimensional electron systems

Three different elements, Silicon, Selenium, and Tellurium, are ion-implanted in Gallium arsenide to form a conducting layer that serves as a back-gate to a molecular beam epitaxy (MBE) overgrown two-dimensional electron gas (2DEG). While the heavy ion Tellurium creates too many damages in the gallium arsenide to form a conducting layer, both Silicon and Selenium show promising results combined with MBE-grown high-quality 2DEGs. Similar 2DEG mobility compared to non-implanted reference samples is achieved for both Silicon and Selenium implanted structures. Individual contacts to the back-gate are challenging. However, Silicon implanted structures, annealed before the MBE growth, result in a function back-gate, and the electron density of the 2DEG is tuned via the back-gate.Comment: 10 pages, 4 figure

Methods of Health Economic Evaluation for Health Services Research

Icks A, Chernyak N, Bestehorn K, et al. Methoden der gesundheitsökonomischen Evaluation in der Versorgungsforschung. Das Gesundheitswesen. 2010;72(12):917-933.On August 30, 2010, the German Network for Health Services Research [Deutsches Netzwerk Versorgungsforschung e.V. (DNVF e.V.)] approved the Memorandum III "Methods for Health Services Research", supported by the member societies mentioned as authors and published in this Journal [Gesundheitswesen 2010; 72: 739-748]. The present paper focuses on methodological issues of economic evaluation of health care technologies. It complements the Memorandum III "Methods for Health Services Research", part 2. First, general methodological principles of the economic evaluations of health care technologies are outlined. In order to adequately reflect costs and outcomes of health care interventions in the routine health care, data from different sources are required (e.g., comparative efficacy or effectiveness studies, registers, administrative data, etc.). Therefore, various data sources, which might be used for economic evaluations, are presented, and their strengths and limitations are stated. Finally, the need for methodological advancement with regard to data collection and analysis and issues pertaining to communication and dissemination of results of health economic evaluations are discussed.Das Deutsche Netzwerk Versorgungsforschung e. V. (DNVF e. V.) hat am 30.08.2010 getragen von den genannten im DNVF organisierten Fachgesellschaften und Organisationen, das Memorandum III „Methoden für die Versorgungsforschung” Teil 2 verabschiedet, das in dieser Zeitschrift publiziert wurde [Gesundheitswesen 2010; 72: 739-748]. Die vorliegende Publikation fokussiert auf die Methodik der ökonomischen Evaluation der Gesundheitstechnologien bzw. Interventionen und stellt eine Vertiefung zu dem Memorandum III „Methoden für die Versorgungsforschung” Teil 2 dar. Zunächst werden allgemeine methodische Standards gesundheitsökonomischer Evaluationen, d. h. Studien, die die Kosten-Nutzen Relation (Wirtschaftlichkeit) von Interventionen untersuchen, kurz dargestellt. Um Versorgungsrealität adäquat zu reflektieren, müssen zur Ermittlung der Interventionskosten und -effekte oft mehrere Datenquellen, z. B. Wirksamkeitsstudien, Register, administrative Quellen usw., verwendet werden. Daher werden für die gesundheitsökonomischen Evaluationen im Rahmen der Versorgungsforschung potenziell geeignete Datenquellen vorgestellt, ihre Vorteile und Limitationen genannt. Anschließend wird der Weiterentwicklungsbedarf der Methodik im Hinblick auf die Datenerhebung, und -auswertung sowie die Kommunikation und Dissemination der Ergebnisse diskutiert

Cranial MRI in ataxia-telangiectasia.

We examined five males with laboratory-confirmed ataxia-telangiectasia (AT), aged 9-28 years, several times by MRI (9 examinations: 5 at 0.15 T, 3 at 0.5 T, 1 at 1.5 T). Intermediate, T1-, T2- and T2*-weighted spin-echo and gradient-echo sequences were performed. All patients showed vermian atrophy, enlarged fourth ventricle and cisterna magna; four showed cerebellar hemisphere atrophy; two enlarged infracerebellar subarachnoid spaces and four patients had sinusitis. No focal areas of abnormal signal were seen in the brain, diffuse high signal was found in the central cerebral white matter of the oldest patient. AT is an important human model of inherited cancer susceptibility and multisystem ageing; as in xeroderma pigmentosum and other "breakage syndromes", ionising radiation should be avoided. When imaging is necessary, MRI should be preferred to CT in patients known or suspected to have AT and those with undefined paediatric ataxias of nontraumatic origin. If atrophy of only the cerebellum, especially the vermis, is noted, laboratory research should be performed to confirm the diagnosis of AT