Step-edge-induced resistance anisotropy in quasi-free-standing bilayer chemical vapor deposition graphene on SiC

Cataloged from PDF version of article.The transport properties of quasi-free-standing (QFS) bilayer graphene on SiC depend on a range of scattering mechanisms. Most of them are isotropic in nature. However, the SiC substrate morphology marked by a distinctive pattern of the terraces gives rise to an anisotropy in graphene's sheet resistance, which may be considered an additional scattering mechanism. At a technological level, the growth-preceding in situ etching of the SiC surface promotes step bunching which results in macro steps similar to 10 nm in height. In this report, we study the qualitative and quantitative effects of SiC steps edges on the resistance of epitaxial graphene grown by chemical vapor deposition. We experimentally determine the value of step edge resistivity in hydrogen-intercalated QFS-bilayer graphene to be similar to 190 Omega mu m for step height h(S) = 10 nm and provide proof that it cannot originate from mechanical deformation of graphene but is likely to arise from lowered carrier concentration in the step area. Our results are confronted with the previously reported values of the step edge resistivity in monolayer graphene over SiC atomic steps. In our analysis, we focus on large-scale, statistical properties to foster the scalable technology of industrial graphene for electronics and sensor applications. (C) 2014 AIP Publishing LLC

Secondary prevention of coronary artery disease in contemporary clinical practice

Background: The highest priority in preventive cardiology was given to patients with estab-lished coronary artery disease (CAD). The aim of the study was to assess the implementation of guidelines for secondary prevention in everyday clinical practice by evaluating control of the main risk factors and the cardioprotective medication prescription rates for patients, following their hospitalization for CAD. Methods: Five hospitals with cardiology departments serving the city and its surround-ing districts in southern part of Poland participated in the study. Consecutive patients aged ≤ 80 years, hospitalized from January 1 2010 to April 31 2012 due to an acute coronary syndrome or for a myocardial revascularization procedure were recruited and interviewed 6–18 months after hospitalization. Results: The medical records of 595 patients (mean age: 62.8 ± 9.0 years, 397 men and 198 women) were reviewed and included in the analyses. Proportions of medical records with available information on risk factors were high with the exception of total cholesterol levels as well as weight and height measurements, which were available in less than 80 % of the hospita

Cardiac rehabilitation in real life

Participation in cardiac rehabilitation programs (CRPs) improves prognosis in patients with coronary artery disease (CAD). However, not much is known about the effectiveness of CRP in real life. The aim of this analysis was to identify factors related to the referral to CRP following hospitalization for CAD and estimate the effectiveness of the programs in real life. Medical records of 1061 consecutive patients aged ≤80 years, hospitalized due to an acute coronary syndrome or for a myocardial revascularization procedure in 5 hospitals serving the city and surrounding counties, were reviewed and 611 patients were interviewed 6–18 months posthospitalization. Of 611 patients participating in the interview, 212 (34.7%) were referred following the hospitalization to a center providing CRP. Age, hospitalization in a teaching hospital, and index diagnosis were independently related to being granted a referral. Among the referred patients, 86.3% participated in the CRP. Participation in CRP was related to the lower probability of having high total cholesterol (23% vs 32%, P < 0.05), fasting glucose (11% vs 18%, P = 0.05), Hb(A1c) (8% vs 16%, P = 0.05), and body mass index (27% vs 37%, P < 0.05). Generally, the effect of the CRP was significant in participants with a higher education, but not in those with a low education level. Other factors were not significantly related to the effectiveness of CRP. This study shows that CRPs are effective, but underused in Poland. The participant's education level may influence the effectiveness of CRP. Therefore, in order to increase the impact of CRP, the content of such programs should vary depending on the education level of the participants

Practice setting and secondary prevention of coronary artery disease

Introduction: Patients with established coronary artery disease (CAD) are at high risk of recurrent cardiovascular events. The aim of the analysis was to compare time trends in the extent to which cardiovascular prevention guidelines have been implemented by primary care physicians and specialists. Material and methods: Five hospitals with cardiology departments serving the city and surrounding districts in the southern part of Poland participated in the study. Consecutive patients hospitalized due to an acute coronary syndrome or for a myocardial revascularization procedure were recruited and interviewed 6-18 months after hospitalization. The surveys were carried out in 1997-1998, 1999-2000, 2006-2007 and 2011-2013. Results: The proportion of smokers increased from 16.0% in 1997–1998 to 16.4% in 2011-2013 among those who declared that a cardiologist in a hospital outpatient clinic decided about the treatment, from 17.5% to 34.0% (p < 0.01) among those treated by a primary care physician, and from 7.0% to 19.7% (p = 0.06) among patients treated in private cardiology practices. The corresponding proportions were 44.6% and 42.4% (p < 0.01), 47.7% and 52.8% (p = 0.53), 44.2% and 42.2% (p = 0.75) for high blood pressure, and 42.5% and 71.2% (p < 0.001), 51.4% and 79.6% (p < 0.001), 52.4% and 72.4% (p < 0.01) for LDL cholesterol level not at recommended goal. The proportion of patients prescribed cardioprotective medications increased in every analyzed group. Conclusions: The control of cardiovascular risk in CAD patients has only slightly improved since 1997/98 in all health care settings. The greatest potential for further improvement was found among patients whose post-hospital care is provided by primary care physicians. It is associated with promotion of a no-smoking policy and enhanced prescription of guideline-recommended drugs

Deep learning-enabled coronary CT angiography for plaque and stenosis quantification and cardiac risk prediction: an international multicentre study

BACKGROUND: Atherosclerotic plaque quantification from coronary CT angiography (CCTA) enables accurate assessment of coronary artery disease burden and prognosis. We sought to develop and validate a deep learning system for CCTA-derived measures of plaque volume and stenosis severity. METHODS: This international, multicentre study included nine cohorts of patients undergoing CCTA at 11 sites, who were assigned into training and test sets. Data were retrospectively collected on patients with a wide range of clinical presentations of coronary artery disease who underwent CCTA between Nov 18, 2010, and Jan 25, 2019. A novel deep learning convolutional neural network was trained to segment coronary plaque in 921 patients (5045 lesions). The deep learning network was then applied to an independent test set, which included an external validation cohort of 175 patients (1081 lesions) and 50 patients (84 lesions) assessed by intravascular ultrasound within 1 month of CCTA. We evaluated the prognostic value of deep learning-based plaque measurements for fatal or non-fatal myocardial infarction (our primary outcome) in 1611 patients from the prospective SCOT-HEART trial, assessed as dichotomous variables using multivariable Cox regression analysis, with adjustment for the ASSIGN clinical risk score. FINDINGS: In the overall test set, there was excellent or good agreement, respectively, between deep learning and expert reader measurements of total plaque volume (intraclass correlation coefficient [ICC] 0·964) and percent diameter stenosis (ICC 0·879; both p<0·0001). When compared with intravascular ultrasound, there was excellent agreement for deep learning total plaque volume (ICC 0·949) and minimal luminal area (ICC 0·904). The mean per-patient deep learning plaque analysis time was 5·65 s (SD 1·87) versus 25·66 min (6·79) taken by experts. Over a median follow-up of 4·7 years (IQR 4·0–5·7), myocardial infarction occurred in 41 (2·5%) of 1611 patients from the SCOT-HEART trial. A deep learning-based total plaque volume of 238·5 mm(3) or higher was associated with an increased risk of myocardial infarction (hazard ratio [HR] 5·36, 95% CI 1·70–16·86; p=0·0042) after adjustment for the presence of deep learning-based obstructive stenosis (HR 2·49, 1·07–5·50; p=0·0089) and the ASSIGN clinical risk score (HR 1·01, 0·99–1·04; p=0·35). INTERPRETATION: Our novel, externally validated deep learning system provides rapid measurements of plaque volume and stenosis severity from CCTA that agree closely with expert readers and intravascular ultrasound, and could have prognostic value for future myocardial infarction

Familial hematuria

Hematuria is a common presenting complaint in pediatric nephrology clinics and often has a familial basis. This teaching article provides an overview of causes, diagnosis, and management of the major forms of familial hematuria, Alport syndrome, and thin basement membrane nephropathy