Quantum Hall resistance standards from graphene grown by chemical vapor deposition on silicon carbide

Replacing GaAs by graphene to realize more practical quantum Hall resistance standards (QHRS), accurate to within $10^{-9}$ in relative value, but operating at lower magnetic fields than 10 T, is an ongoing goal in metrology. To date, the required accuracy has been reported, only few times, in graphene grown on SiC by sublimation of Si, under higher magnetic fields. Here, we report on a device made of graphene grown by chemical vapour deposition on SiC which demonstrates such accuracies of the Hall resistance from 10 T up to 19 T at 1.4 K. This is explained by a quantum Hall effect with low dissipation, resulting from strongly localized bulk states at the magnetic length scale, over a wide magnetic field range. Our results show that graphene-based QHRS can replace their GaAs counterparts by operating in as-convenient cryomagnetic conditions, but over an extended magnetic field range. They rely on a promising hybrid and scalable growth method and a fabrication process achieving low-electron density devices.Comment: 12 pages, 8 figure

Incomplete echocardiographic recovery at 6\ua0months predicts long-term sequelae after intermediate-risk pulmonary embolism. A post-hoc analysis of the Pulmonary Embolism Thrombolysis (PEITHO) trial

Introduction: Symptoms and functional limitation are frequently reported by survivors of acute pulmonary embolism (PE). However, current guidelines provide no specific recommendations on which patients should be followed after acute PE, when follow-up should be performed, and which tests it should include. Definition and classification of late PE sequelae are evolving, and their predictors remain to be determined. Methods: In a post hoc analysis of the Pulmonary Embolism Thrombolysis (PEITHO) trial, we focused on 219 survivors of acute intermediate-risk PE with clinical and echocardiographic follow-up 6 months after randomisation as well as over the long term (median, 3 years after acute PE). The primary outcome was a composite of (1) confirmed chronic thromboembolic pulmonary hypertension (CTEPH) or (2) \u2018post-PE impairment\u2019 (PPEI), defined by echocardiographic findings indicating an intermediate or high probability of pulmonary hypertension along with New York Heart Association functional class II\u2013IV. Results: Confirmed CTEPH or PPEI occurred in 29 (13.2%) patients, (6 with CTEPH and 23 with PPEI). A history of chronic heart failure at baseline and incomplete or absent recovery of echocardiographic parameters at 6 months predicted CTEPH or PPEI at long-term follow-up. Conclusions: CTEPH or PPEI occurs in almost one out of seven patients after acute intermediate-risk PE. Six-month echocardiographic follow-up may be useful for timely detection of late sequelae

BMJ Open

Objectives Presently, those outcomes that should be prioritised for chronic obstructive pulmonary disease (COPD) exacerbation studies remain unclear. In order to coordinate multicentre studies on eosinophilia-driven corticosteroid therapy for patients hospitalised for acute exacerbation of COPD (AECOPD), we aimed to find consensus among experts in the domain regarding the prioritisation of outcomes. Design A modified Delphi study was proposed to recognised COPD experts. Two brainstorming questionnaires were used to collect potential outcomes. Four subsequent rounds of questionnaires were used to rank items according to a six-point Likert scale for their importance in the protocol, as well as for being the primary outcome. Priority outcome criteria were predefined as those for which ≥70% of experts indicated that the outcome was essential for interpreting study results. Setting COPD exacerbation management in France. Participants 34 experts recommended by the French Language Pulmonology Society were invited to participate. Of the latter, 21 experts participated in brainstorming, and 19 participated in all four ranking rounds. Results 105 outcomes were ranked. Two achieved consensus as candidate primary outcomes: (1) treatment failure defined as death from any cause or the need for intubation and mechanical ventilation, readmission because of COPD or intensification of pharmacologic therapy, and (2) the time required to meet predefined discharge criteria. The 10 secondary priority outcomes included survival, time with no sign of improvement, episodes of hospitalisation, exacerbation, pneumonia, mechanical or non-invasive ventilation and oxygen use, as well as comorbidities during the initial hospitalisation. Conclusions This Delphi consensus project generated and prioritised a great many outcomes, documenting current expert views concerning a diversity of COPD endpoints. Among the latter, 12 reached consensus as priority outcomes for evaluating the efficacy of eosinophil-driven corticosteroid therapy in AECOPD inpatients

Rasiowa–Sikorski deduction systems in computer science applications

AbstractA Rasiowa-Sikorski system is a sequence-type formalization of logics. The system uses invertible decomposition rules which decompose a formula into sequences of simpler formulae whose validity is equivalent to validity of the original formula. There may also be expansion rules which close indecomposable sequences under certain properties of relations appearing in the formulae, like symmetry or transitivity. Proofs are finite decomposition trees with leaves having “fundamental”, valid labels. The author describes a general method of applying the R-S formalism to develop complete deduction systems for various brands of C.S and A.I. logic, including a logic for reasoning about relative similarity, a three-valued software specification logic with McCarthy's connectives and Kleene quantifiers, a logic for nondeterministic specifications, many-sorted FOL with possibly empty carriers of some sorts, and a three-valued logic for reasoning about concurrency

The management of acute venous thromboembolism in clinical practice. Results from the European PREFER in VTE Registry

Venous thromboembolism (VTE) is a significant cause of morbidity and mortality in Europe. Data from real-world registries are necessary, as clinical trials do not represent the full spectrum of VTE patients seen in clinical practice. We aimed to document the epidemiology, management and outcomes of VTE using data from a large, observational database. PREFER in VTE was an international, non-interventional disease registry conducted between January 2013 and July 2015 in primary and secondary care across seven European countries. Consecutive patients with acute VTE were documented and followed up over 12 months. PREFER in VTE included 3,455 patients with a mean age of 60.8 ± 17.0 years. Overall, 53.0 % were male. The majority of patients were assessed in the hospital setting as inpatients or outpatients (78.5 %). The diagnosis was deep-vein thrombosis (DVT) in 59.5 % and pulmonary embolism (PE) in 40.5 %. The most common comorbidities were the various types of cardiovascular disease (excluding hypertension; 45.5 %), hypertension (42.3 %) and dyslipidaemia (21.1 %). Following the index VTE, a large proportion of patients received initial therapy with heparin (73.2 %), almost half received a vitamin K antagonist (48.7 %) and nearly a quarter received a DOAC (24.5 %). Almost a quarter of all presentations were for recurrent VTE, with >80 % of previous episodes having occurred more than 12 months prior to baseline. In conclusion, PREFER in VTE has provided contemporary insights into VTE patients and their real-world management, including their baseline characteristics, risk factors, disease history, symptoms and signs, initial therapy and outcomes

Landau levels analysis by using symmetry properties of mesoscopic Hall bars

We use the resistance fluctuations (RFs) appearing in the integer quantum Hall regime to scan the density of states of a very thin Hall bar. By applying a dc voltage on a top gate, we analyze the correlation properties of the various resistances as a function of the magnetic field and the carrier density. In the gate voltage-magnetic field plane, these RFs follow lines with slopes quantized in unit of filling factor and the slope of these RFs depends on their correlation properties

Local spectroscopy of Landau levels in mesoscopic Hall bars

We performed a local spectroscopy of the Landau levels density of states using gated mesoscopic Hall bars placed at very low temperature in the integer quantum Hall regime. The transverse and longitudinal conductances were measured while scanning both the two-dimensional electron density and the applied magnetic field. We observe a succession of sharp peaks due to backscattering across the samples caused by tunneling effects. Using temperature as a parameter in the range of 0.1-1 K, we characterize those tunnel processes: a resonant double-barrier tunneling and a single-barrier tunneling which corresponds to the variable range hopping regime. We show that for vanishing temperature and noninteger filling factor nu the conductance sigma(T=0, nu) does not vanish unlike the case of wide samples: instead, it converges to a limit function sigma(S)(nu) that is a noisy image of the Landau levels density of states