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We use scanning gate microscopy to study electron transport through an open, gate-defined resonator in a Ga(Al)As heterostructure. Raster-scanning the voltage-biased metallic tip above the resonator, we observe distinct conductance modulations as a function of the tip position and voltage. Quantum-mechanical simulations reproduce these conductance modulations and reveal their relation to the partial local density of states in the resonator. Our measurements illustrate the current frontier between possibilities and limitations in imaging the local density of states in buried electron systems using scanning gate microscopy., Physical Review Research, 3 (3), ISSN:2643-1564

An open resonator fabricated in a two-dimensional electron gas is used to explore the transition from strongly invasive scanning gate microscopy to the perturbative regime of weak tip-induced potentials. With the help of numerical simulations that faithfully reproduce the main experimental findings, we quantify the extent of the perturbative regime in which the tip-induced conductance change is unambiguously determined by properties of the unperturbed system. The correspondence between the experimental and numerical results is established by analyzing the characteristic length scale and the amplitude modulation of the conductance change. In the perturbative regime, the former is shown to assume a disorder-dependent maximum value, while the latter linearly increases with the strength of a weak tip potential., Comment: 11 pages, 7 figures

We report on Coulomb drag experiments between a bilayer graphene flake and a GaAs two-dimensional electron gas, where the charge-carrier densities of both systems can be tuned independently. For both p- and n-type graphene charge carriers, we observe that the Coulomb drag unexpectedly changes direction when the temperature is lowered. We find this phenomenon to be dominant when the Fermi wave vector in graphene is larger than in GaAs. At temperatures above $\approx 70\,{\rm{K}}$, the drag signal is consistent with momentum exchange. In all discussed regimes, the Onsager relation is respected., New Journal of Physics, 19 (10), ISSN:1367-2630

Guidelines have been published for improving management of chronic heart failure (CHF). We examined the association between improved guideline adherence and risk for all-cause death in patients with stable systolic HF.Data on ambulatory patients (2006-2010) with CHF and reduced ejection fraction (HF-REF) from the Austrian Heart Failure Registry (HIR Austria) were analysed. One-year clinical data and long-term follow-up data until all-cause death or data censoring were available for 1014 patients (age 65 [55-73], male 75%, NYHA class I 14%, NYHA II 56%, NYHA III/IV 30%). A guideline adherence indicator (GAI [0-100%]) was calculated for each patient at baseline and after 12 ± 3 months that considered indications and contraindications for ACE-I/ARB, beta blockers, and MRA. Patients were considered ΔGAI-positive if GAI improved to or remained at high levels (≥ 80%). ΔGAI50+ positivity was ascribed to patients achieving a dose of ≥ 50% of suggested target dose.Improvements in GAI and GAI50+ were associated with significant improvements in NYHA class and NT-proBNP (1728 [740-3636] to 970 [405-2348]) (p0.001). Improvements in GAI50+, but not GAI, were independently predictive of lower mortality risk (HR 0.55 [95% CI 0.34-0.87; p=0.01]) after adjustment for a large variety of baseline parameters and hospitalisation for heart failure during follow-up.Improvement in guideline adherence with particular emphasis on dose escalation is associated with a decrease in long-term mortality in ambulatory HF-REF subjects surviving one year after registration.

Die Herzinsuffizienz stellt mit einer geschatzten Pravalenz von 0,4–2% in Europa eine der haufigsten Erkrankungen der westlichen Welt dar. Haufigkeit und Inzidenz sind stark altersabhangig, und die chronische Herzinsuffizienz hat stadienabhangig eine hohe Sterblichkeit. Diagnostik und Therapie der chronischen Herzinsuffizienz unterliegen einem stetigen Wandel, bedingt zum einen durch die Fortschritte in der Forschung und zum anderen durch neue randomisierte Studien. Diese Ubersichtsarbeit fasst alle aktuellen Empfehlungen zur Diagnostik und Therapie der chronischen Linksherzinsuffizienz zusammen. Dabei werden Erkenntnisse bei den kardialen Biomarkern, der Echokardiographie, der Spiroergometrie und den bildgebenden Verfahren kritisch diskutiert und innovative Therapieansatze wie Ivabradin oder die medikamentose Therapie der pulmonalen Hypertonie bei Linksherzinsuffizienz vorgestellt. Neben den medikamentosen Strategien werden auch potenzielle Device-Therapien wie MitraClip®, operative Masnahmen und die Herztransplantation erortert.

Global Initiative for Chronic Obstructive Lung Disease (GOLD) criteria (FEV1/FVC70%) are extensively used for diagnosis of chronic obstructive lung disease in heart failure (HF). The American Thoracic Society (ATS)/European Respiratory Society (ERS) recommends the use of age- and gender-specific lower limit of normal (LLN) for FEV1/FVC. We compared the impact of these definitions on apparent prevalence of airway obstruction in chronic HF.Standardized pre- and post-bronchodilator spirometry was performed in HF patients. Airway obstruction was defined by ATS/ERS criteria as diagnostic standard. Additionally, airway obstruction was calculated using the GOLD criteria.Of the 89 participants who fulfilled the ATS criteria for acceptability and reproducibility, 24.7% met ATS/ERS and 43.8% GOLD criteria for airway obstruction (Chi-square p = 0.007, McNemar0.001). Sensitivity of GOLD criteria was 100%, specificity 74.6%, positive predictive value 56.4% and negative predictive value 100%. Among all individuals with an FEV1/FVCLLN, 25.4% were falsely identified when using the GOLD criteria. A majority of false positives qualified for airway obstruction GOLD stage I (FEV1% ≥80%), which was significantly less often observed among true positives (76.5 vs. 31.8%; p0.001). Only 31.8% of patients with irreversible airway obstruction detected by the ATS/ERS criteria reported a history of COPD.In all HF patients with persistent dyspnoea despite optimal HF treatment, spirometric testing should be performed. Application of the GOLD criteria leads to overdiagnosis of irreversible airway obstruction in patients with HF, which may result in inappropriate medical therapy and health-care decisions.

Arrhythmogenic right ventricular dysplasia (ARVD) is often associated with progressive right ventricular dysfunction. Although heart transplantation (HTx) is suggested in these patients, indication and optimal timing for listing can be challenging. The study comprises four patients (two male, range: 37–56 years) with advanced ARVD who were considered for HTx. Standard inclusion criteria for HTx listing such as clinical signs, New York Heart Association (NYHA) classification (II-III), and N-terminal pro-brain natriuretic peptide (NT-proBNP) (3672 ± 1407 pg/ml) were heterogeneous and did not add unequivocally to decision making. In all patients, though, right heart hemodynamics revealed Fontan-like circulation (FLC) with equilibrated pressure tracings between the right atrium (16 ± 4 mmHg) and the pulmonary artery (16 ± 5 mmHg). In this condition, the pulmonary blood flow can be regarded as nearly non-pulsatile, as it is passive and propelled by the transpulmonary gradient and intrathoracic pressure alterations produced by breathing to the left atrium. Based on these findings, all patients were listed for HTx and were finally successfully transplanted. In patients with ARVD, evidence of FLC may serve as an additional criterion for HTx. This applies particularly to patients who do not clearly fulfill standard transplant criteria and to patients with electrical instability.