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Resistive-switching random access memory (RRAM) devices utilizing a crossbar architecture represent a promising alternative for Flash replacement in high-density data storage applications. However, RRAM crossbar arrays require the adoption of diodelike select devices with high on–off -current ratio and with sufficient endurance. To avoid the use of select devices, one should develop passive arrays where the nonlinear characteristic of the RRAM device itself provides self-selection during read and write. This paper discusses the complementary switching (CS) in hafnium oxide RRAM, where the logic bit can be encoded in two high-resistance levels, thus being immune from leakage currents and related sneak-through effects in the crossbar array. The CS physical mechanism is described through simulation results by an ion-migration model for bipolar switching. Results from pulsed-regime characterization are shown, demonstrating that CS can be operated at least in the 10-ns time scale. The minimization of the reset current is finally discussed. [ABSTRACT FROM AUTHOR]

Understanding the physical mechanisms for resistance change in metal oxides is a key challenge to assess the scalability of resistive-switching random access memory (RRAM) devices. From this standpoint, the time dependence of filament formation and dissolution in metal oxides can provide a useful insight into the fundamental mechanism of resistive switching. In this paper, we show an experimental study of the time-dependent filament growth and of the voltage dependence of set/reset times in \HfOx-based RRAM devices. The voltage across the device is shown to be regulated at any given time irrespective of the compliance current and the applied voltage, evidencing that voltage is the controlling parameter for the filament formation and dissolution during switching. These results are explained in terms of a thermally-activated ion migration model for filamentary switching. The model allows for an analytical calculation of the scaling dependence of set/reset times and energies in RRAM. [ABSTRACT FROM AUTHOR]

A bstract Background: Atrial fibrillation (AF) is a common complication of coronary artery bypass grafting (CABG). However, limited information is available about the role of preoperative echocardiographic left atrial evaluation to predict AF occurrence after CABG. Thus, we prospectively compared the ability of echocardiographic measurements of left atrial volume to predict AF in this setting. Methods: From January to December 2009, 220 patients (75% males, 66.8 ± 10.0 years) met the inclusion criteria of our study (isolated and elective CABG, no valve surgery, no permanent AF, or other chronic atrial arrhythmias). The day before CABG a complete echocardiographic evaluation was performed with left atrial volume measurements. The primary endpoint of the study was postoperative AF (POAF) lasting >30 seconds. Results: POAF was observed in 61 patients (27.7%). POAF patients showed increased left atrial M-mode anteroposterior dimension (41.2 ± 6.4 mm vs. 43.6 ± 7.3 mm; p = 0.020) and increased left atrial volume (59.0 ± 18.3 mL vs. 70.6 ± 28.1 mL; p = 0.0004). Left atrial volume was an independent risk factor for POAF (OR 10.03; 95% CI 10.01 to 10.05; p = 0.01), along with postoperative bleeding with hemoglobin levels below 8 g/dL (OR 20.84; 95% CI 10.12 to 70.19; p = 0.03) and preoperative left ventricular ejection fraction below 40% (OR 10.08; 95% CI 10.01 to 10.15; p = 0.02). Conversely, preoperative statin therapy exerted a protective role (OR 0.30; 95% CI 0.12 to 0.74; p = 0.009). Conclusion: Preoperative echocardiographic evaluation of patients with isolated CABG demonstrated that left atrium volume measurements were independently correlated to the occurrence of POAF. Further investigations should focus on the opportunity to target prophylactic antiarrhythmic treatments to patients with large left atrial volumes. (J Card Surg 2012;27:128-135) [ABSTRACT FROM AUTHOR]

Set and reset characteristics are studied for unipolar and bipolar metal-oxide resistive-switching memory devices. We show a universal dependence of set-state resistance and reset current on the compliance current used during set, with negligible impact of metal-oxide composition and switching condition. An analytical Joule-heating model for universal reset is presented, predicting a weak dependence of reset temperature and voltage on diffusion and migration parameters in both unipolar- and bipolar-switching modes. Data for the reset voltage are shown for a wide range of unipolar and bipolar metal oxides, in support of our calculations. [ABSTRACT FROM AUTHOR]

Resistive-switching memory (RRAM) devices are attracting a considerable interest in view of their back-end integration, fast programming, and high scalability. Prediction the programming voltages and currents as a function of the operating conditions is an essential task for developing compact and numerical models able to handle a large number (106-109) of cells within an array. Based on recent experimental findings on the set and reset processes, we have developed physics-based analytical models for the set and reset operations in NiO-based RRAMs. Simulation results obtained by the analytical models were compared with experimental data for variable pulse conditions and were found consistent with data. The set transition is described by a threshold switching process at the broken conductive filament (CF), while the reset transition is viewed as a thermally driven dissolution and/or oxidation of the CF. Set and reset models are finally used for reliability predictions of failure times under constant-voltage stress (read disturb) and elevated-temperature bake (data retention). [ABSTRACT FROM AUTHOR]

Resistive-switching memory (RRAM) is attracting a considerable interest for the development of high-density nonvolatile memories. However, several scaling and reliability issues still affect the development path of RRAM. This work addresses random telegraph-signal noise (RTN) of the RRAM current, potentially affecting the memory stability. We show a clear resistance dependence of the RTN amplitude, and we propose a physical model describing the interaction of the localized current with a fluctuating defect. By estimating the diameter of the conductive filament, the model quantitatively accounts for the observed RTN amplitude, thus allowing for an analytical prediction of state stability in RRAMs. [ABSTRACT FROM AUTHOR]

Abstract Aims To describe the contemporary management by cardiologists of patients after an episode of myocardial infarction (MI). Methods The EYESHOT Post-MI was a prospective, observational, nationwide study aimed to evaluate the management of patients referring to cardiologists 1 to 3 years from the last MI event. Results Over a 3-month period, 1633 consecutive patients [median 22 (IQR 15–28) months from MI] were enrolled: 1028 (63.0%) at the second and 605 (37.0%) at the third year from MI. During the 12 months prior to enrolment, the majority of patients received a transthoracic echocardiogram (60% and 54%), followed by coronary angiography (24% and 16%, in the second and third year from MI groups, respectively). At the time of enrolment, the majority of patients were prescribed on statins (93%) and beta-blockers (82%), without significant differences between the 2 groups. A dual antiplatelet therapy (DAPT) was used more frequently among patients presenting during the second compared to the third year from MI (40% vs 24%; p < 0.0001). At multivariable analysis, the time interval from last MI (2 vs 3 years: OR 2.27; 95% CI 1.79–2.88; p < 0.0001) and a previous percutaneous coronary intervention with multiple stents (OR 3.46; 95% CI 2.19–5.47; p < 0.0001) resulted as the major independent predictors of DAPT persistence at the time of enrolment. Conclusions This contemporary registry provides unique insights into the current management of post-MI patients and represents an opportunity to further improve the long-term treatment of this high-risk population. Highlights • The EYESHOT Post-MI evaluated the management of patients referring to cardiologists 1 to 3 years from the last MI event. • Over a 3-month period, 1633 patients were enrolled: 1028 (63.0%) at the second and 605 (37.0%) at the third year from MI. • During the 12 months prior to enrolment, the majority of patients received a transthoracic echocardiogram, followed by coronary angiography. • A dual antiplatelet therapy (DAPT) was used more frequently among patients presenting during the second compared to the third year from MI. [ABSTRACT FROM AUTHOR]

Abstract: Background: Drug eluting balloons (DEB) have been developed to overcome the limitations of drug eluting stents (DES), but clinic results of various DEB studies are still not consistent. Thus, we performed a meta-analysis to compare outcomes of DEB and DES for the treatment of coronary artery disease (CAD). Methods: Medline/Web databases were searched for studies comparing DEB and DES for obstructive CAD, reporting late lumen loss (LLL) and rates for overall mortality, myocardial infarction (MI), stent thrombosis (ST) and target lesion revascularization (TLR). Results: 8 studies (1462 patients) were included in the meta-analysis. Compared with DES, DEB treated patients showed non-significantly higher LLL (weighted mean difference [WMD] 0.32, 95% confidence interval [CI] −0.15 to 0.78, P=0.18) and non-significantly higher rate of binary restenosis (odds ratio [OR] 1.40 [0.68–2.48], P=0.36). Mortality (OR 1.13[0.54–2.37], P=0.74), MI (OR 0.95, [0.50–1.80], P=0.87), ST (OR 1.12, [0.34–4.19], P=0.77) and TLR rates (OR 1.19[0.60–2.38], P=0.61) were similar between the 2 treatments. A pre-specified meta-regression analysis showed that LLL WMD and TLR OR were inversely correlated to the prevalence of diabetes (P<0.0001) and directly correlated to reference coronary diameters (P<0.001). Conclusions: The present meta-analysis showed that compared to DES, DEB use resulted in similar clinical efficacy and safety. Thus DEB could be considered a reasonable alternative to DES for the treatment of CAD in selected clinical settings (Clinicaltrials.gov identifier: NCT01760200). [Copyright &y& Elsevier]

Yersinia enterocolitica is an unusual cause of septicaemia, usually occurring in immunocompromised hosts. Endocardial involvement is rare and generally presents as acute endocarditis. We describe the case of a 73-y-old woman, apparently without risk factors for endocarditis, admitted to hospital for persistent fever of unknown origin, arthralgia, and weight loss. Y. enterocolitica was isolated from blood and urine cultures, and echocardiography showed a pedunculated vegetation attached to the non-coronary cusp of the aortic valve. Symptoms and fever resolved after 3 days of intravenous cefotaxime plus amikacin, which were continued for the 2 weeks of her hospital stay; this treatment was followed by intravenous ceftriaxone after discharge. We hypothesized that a chemotherapy course administered 2 months previously for breast cancer might have been a predisposing factor for the Y. enterocolitica valvular infection and that immune system recovery contributed to mitigate the clinical presentation as subacute endocarditis. [ABSTRACT FROM AUTHOR]