Stochastic Thermodynamics of an Electromagnetic Energy Harvester.

We study the power extracted by an electromagnetic energy harvester driven by broadband vibrations. We describe the system with a linear model, featuring an underdamped stochastic differential equation for an effective mass in a harmonic potential, coupled electromechanically with the current in the circuit. We compare the characteristic curve (power vs. load resistance) obtained in experiments for several values of the vibration amplitude with the analytical results computed from the model. Then, we focus on a more refined analysis, taking into account the temporal correlations of the current signal and the fluctuations of the extracted power over finite times. We find a very good agreement between the analytical predictions and the experimental data, showing that the linear model with effective parameters can describe the real system, even at the fine level of fluctuations. Our results could be useful in the framework of stochastic thermodynamics applied to energy harvesting systems.

Stochastic Thermodynamics of a Piezoelectric Energy Harvester Model.

We experimentally study a piezoelectric energy harvester driven by broadband random vibrations. We show that a linear model, consisting of an underdamped Langevin equation for the dynamics of the tip mass, electromechanically coupled with a capacitor and a load resistor, can accurately describe the experimental data. In particular, the theoretical model allows us to define fluctuating currents and to study the stochastic thermodynamics of the system, with focus on the distribution of the extracted work over different time intervals. Our analytical and numerical analysis of the linear model is succesfully compared to the experiments.

Time course of the survival advantage of transcatheter over surgical aortic valve replacement: Interplay between sex and patient risk profile.

OBJECTIVES: The aim of this study was to explore the time course of survival advantage of TAVR over SAVR as function of the patients' risk and sex. BACKGROUND: Women have been reported to have better survival than men undergoing transcatheter aortic valve replacement (TAVR). However, scant data on the sex-based survival benefit of TAVR over surgical aortic valve replacement (SAVR) are available. METHODS: A systematic review of studies reporting clinical outcomes of men and women undergoing TAVR or SAVR was performed. Studies were divided into two groups according to average patient's risk score and the interplay of surgical risk and sex on outcomes were analyzed. RESULTS: Eight studies involving 6,596 women and 7,204 men patients were extracted. Unlike mens, women patients had survival advantage from TAVR over SAVR that became substantial at 1 year from index procedure and persisted at 2-year of follow-up. Moreover, this sex-based TAVR survival advantage was mainly observed in higher surgical risk patients. Men showed a significantly lower rate of residual paravalvular leak after SAVR. CONCLUSIONS: Women patients had a selective mortality benefit from TAVR compared to SAVR. This sex-based TAVR benefit was mainly observed in high surgical risk patients beyond 1 year from procedure.

Low Power Contactless Voltage Sensor for Low Voltage Power Systems.

Contactless measurements represent the desirable solution in many contexts, where minimal cabling is required or, in general, cabling is not possible. This paper presents a new contactless voltage sensor for low voltage power systems. It is based on a contactless capacitive probe, which surrounds the power cable. It has two concentric electrodes insulated by a shield. A low power analog conditioning circuit evaluates the power line voltage by measuring the current in one of the capacitances of the probe. All the single stages of the circuit have been designed by using low-power rail-to-rail operational amplifiers, supplied at 3.3 V, in order to minimize the power absorption. The sensor has been characterized in various conditions, with sine waves and distorted signals, varying the frequency and the harmonic distortion. The influence of the current, flowing into the power cable, on the voltage measurement has been evaluated too. It shows a good accuracy (lower than 0.3%) from 100 V to 300 V, with a power consumption less than 5 mW.

Predictors of relapse, death or heart transplantation in myocarditis before the introduction of immunosuppression: negative prognostic impact of female gender, fulminant onset, lower ejection fraction and serum autoantibodies.

AIMS: Outcome predictors in myocarditis are not well defined; we aimed at identifying predictors of death, heart transplantation (HTx) and relapse before the introduction of immunosuppression. METHODS AND RESULTS: From 1992 to 2012, 466 consecutive patients (68% male, mean age 37 ± 17 years, single centre recruitment, median follow-up 50 months) were included, of whom 216 had clinically suspected and 250 biopsy-proven myocarditis. Serum anti-heart (AHA) and anti-intercalated disk (AIDA) autoantibodies were measured by indirect immunofluorescence. Univariable and multivariable analyses of clinical and diagnostic features at diagnosis were performed. Survival free from death or HTx at 10 years was 83% in the whole study population and was lower in biopsy-proven versus clinically suspected myocarditis (76% vs. 94%, p < 0.001). Female gender (hazard ratio [HR] 2.7, 95% confidence interval [CI] 1.1-6.5), fulminant presentation (HR 13.77, 95% CI 9.7-261.73), high-titre organ-specific AHA (HR 4.2, 95% CI 1.2-14.7) and anti-nuclear antibodies (ANA) (HR 5.2, 95% CI 2.1-12.8) were independent predictors of death or HTx; higher echocardiographic left ventricular ejection fraction (LVEF) at diagnosis was protective, with a 0.93-fold risk reduction for each 1% LVEF increase (95% CI 0.89-0.96). History of myocarditis at diagnosis (HR 8.5, 95% CI 3.5-20.7) was an independent predictor of myocarditis relapse at follow-up; older age was protective (HR 0.95, 95% CI 0.91-0.99). Predictors of death, HTx and relapse did not differ in biopsy-proven versus clinically suspected myocarditis. CONCLUSIONS: Young age and a previous myocarditis were independent relapse predictors; female gender, fulminant onset, lower LVEF at presentation and high-titre organ-specific AHA and ANA were independent predictors of death and HTx, suggesting that autoimmune features predict worse prognosis.

Monitoring Patients Reported Outcomes after Valve Replacement Using Wearable Devices: Insights on Feasibility and Capability Study: Feasibility Results.

Wearable devices (WDs) can objectively assess patient-reported outcomes (PROMs) in clinical trials. In this study, the feasibility and acceptability of using commercial WDs in elderly patients undergoing transcatheter aortic valve replacement (TAVR) or surgical aortic valve replacement (SAVR) will be explored. This is a prospective observational study. Participants were trained to use a WD and a smartphone to collect data on their physical activity, rest heart rate and number of hours of sleep. Validated questionnaires were also used to evaluate these outcomes. A technology acceptance questionnaire was used at the end of the follow up. In our participants an overall good compliance in wearing the device (75.1% vs. 79.8%, SAVR vs. TAVR) was assessed. Half of the patients were willing to continue using the device. Perceived ease of use is one of the domains that scored higher in the technology acceptance questionnaire. In this study we observed that the use of a WD is accepted in our frail population for an extended period. Even though commercial WDs are not tailored for clinical research, they can produce useful information on patient behavior, especially when coordinated with intervention tailored to the single patient.

Multi-objective adaptive sliding manifold control for More Electric Aircraft.

The increased usage of electric and electronic devices on board the aircraft requested by the "More Electric Aircraft" (MEA) requires the adoption of multi-objective control algorithms, with controllers (supervisors) able to autonomously switch among different objectives. However, the operating point changes during operations, and "small signal" analysis becomes inconclusive to assess overall stability. Thus, the use of standard Proportional-Integral (PI) or Proportional-Integral-Derivative (PID) controllers may become an issue. In this paper, by using nonlinear mathematical tools, the theoretic stability of the controlled electrical devices is considered. Two different control tasks are considered, namely battery charging and generator current limiting. Then an automaton supervisor switches between the two control objectives. Each objective is achieved by using a sliding mode control with adaptive sliding manifold. The adaptation strategy increases robustness, and is crucial for MEA applications, since the controlled system parameters are highly uncertain, due to their harsh environment. Rigorous stability proofs are given, along with detailed simulations in different scenarios. Also hardware implementation is proposed and a comparison with existing strategies (i.e., the Proportional-Integral) is presented, showing the effectiveness of the proposed approach.

Transcatheter aortic valve implantation in patients younger than 75 years: Guidelines-based patients selection and clinical outcome.

BACKGROUND: Patients treated by transcatheter aortic valve implantation (TAVI) in all major recent trials are still mostly octogenarians. Aim of this study is to analyze the risk profile and outcome of TAVI patients <75 years. METHODS AND RESULTS: We retrospectively analyzed 172 patients <75 years with symptomatic severe native AS or degeneration of surgical aortic bioprosthesis treated with TAVI. The level of surgical risk was reassessed according to multiparametric ACC classification (prohibitive in 68 patients, high in 34, intermediate in 70). Mean age was 69.02 ±â€¯6.18 years, mean STS score 5.56 ±â€¯5.21. The majority of them presented one or more clinical or anatomical characteristics favoring TAVI according to ECS guidelines, despite the young age. Vascular access was transfemoral in 76%. According to the VARC-2 definitions, device success was high (90%) in all groups. The early safety was 89%, clinical recovery was slower in prohibitive risk patients. Bleeding events were more frequent in prohibitive and high surgical risk classes. Clinical efficacy at 1 year was overall 83%, and significantly better in intermediate risk patients (p = 0.004). The functional status remained stable over time as well as prostheses performance. CONCLUSION: About 40% of patients <75 years were treated by TAVI due to the presence of a prohibitive risk, mainly related to technical impediments. The remaining was referred to TAVI due to an estimated high or intermediate surgical risk driven by STS score, frailty and/or major organ system compromise. Early and mid-term clinical and hemodynamic outcomes were good, in particular in intermediate risk patients.

Survival After Varying Revascularization Strategies in Patients With ST-Segment Elevation Myocardial Infarction and Multivessel Coronary Artery Disease: A Pairwise and Network Meta-Analysis.

OBJECTIVES: The authors conducted a systematic pairwise and network meta-analysis to assess optimal treatment strategies in patients with ST-segment elevation myocardial infarction (STEMI) and multivessel coronary artery disease (MV-CAD) undergoing primary percutaneous coronary intervention (PCI). BACKGROUND: Patients with STEMI and MV-CAD have a worse prognosis than those with single-vessel CAD. The optimal revascularization strategy for these patients is uncertain. METHODS: Studies of revascularization strategies for MV-CAD in STEMI patients undergoing primary PCI published between 2001 and 2015 were identified using an electronic search. Pairwise and network meta-analyses were performed for 3 PCI strategies in prospective and retrospective studies: 1) infarct-related artery (IRA)-only PCI; 2) single procedure MV-PCI; and 3) staged MV-PCI. Information on study design, inclusion and exclusion criteria, and clinical outcomes was extracted. The outcomes of interest were short-term and long-term mortality. RESULTS: Thirty-two studies (13 prospective and 19 retrospective) with 54,148 patients (IRA-only PCI [n = 42,112], single procedure MV-PCI [n = 8,138], and staged MV-PCI [n = 3,898]) were included in the analysis. Pairwise meta-analyses showed that staged MV-PCI was associated with lower short-term and long-term mortality compared with both IRA-only PCI and single stage MV-PCI, whereas IRA-only PCI was associated with lower mortality compared with single stage MV-PCI. Staged MV-PCI was also associated consistently with improved survival in network analyses. CONCLUSIONS: The present systematic review and meta-analysis supports the hypothesis that in patients with MV-CAD presenting with STEMI undergoing primary PCI, a staged multivessel revascularization strategy may improve early and late survival.

[Endomyocardial biopsy should be performed in every patient with suspected myocarditis]. / La biopsia endomiocardica nella miocardite acuta: per tutti i pazienti.

The diagnosis of myocarditis is difficult because there is no pathognomonic clinical presentation and the disease may mimic other non-inflammatory diseases. Thus, current classifications on cardiomyopathies (e.g., the World Health Organization and the International Society and Federation of Cardiology [WHO/ISFC], the European Society of Cardiology [ESC], and the 2013 Expert Myocarditis ESC Task Force) define myocarditis as an inflammatory disease of the myocardium, which is diagnosed on endomyocardial biopsy (EMB) based upon histological, immunological, immunohistochemical and molecular tools. This will identify etiology, and differentiate between infectious, mainly viral, and non-infectious, immune-mediated forms. The term "inflammatory cardiomyopathy" may be applied in biopsy-proven myocarditis with associated left, right or biventricular dysfunction. Myocarditis may resolve spontaneously, relapse or become chronic progressing to dilated cardiomyopathy, death or heart transplantation. The 2013 Myocarditis ESC Task Force consensus document recommends consideration of EMB and selective coronary angiography in all patients with clinically suspected myocarditis according to the Task Force criteria. It is recommended that EMB analysis includes not only histology (Dallas criteria), but also immunohistology and detection of the genome of infectious agents by molecular tools. EMB should be performed by expert teams. The rationale for this diagnostic effort is the availability of a wide range of immunosuppressive or immunomodulatory agents that, as shown in systemic extracardiac autoimmune disease and in many clinical studies, can be used in infection-negative myocarditis patients to stop or at least stabilize chronic cardiac tissue damage mediated by the immune system, and thus prevent fibrosis and progression to irreversible end-stage dilated cardiomyopathy.

Passive transfer of affinity-purified anti-heart autoantibodies (AHA) from sera of patients with myocarditis induces experimental myocarditis in mice.

BACKGROUND: Human autoimmune myocarditis is characterized by an increased frequency of serum organ and disease-specific anti-heart autoantibodies (AHA) in affected patients. To assess whether AHA are directly pathogenic, we used the passive transfer technique of AHA from patients to normal Balb/c mice to induce an experimental myocarditis. METHODS: In keeping with a classical passive transfer experiment, sera from 5 AHA positive myocarditis patients (3 male, mean age 30 ± 11 years, 3 with giant cell and 2 with lymphocytic myocarditis) were affinity purified and injected into 25 Balb/c mice. As controls, affinity purified sera from 5 healthy donors were passively transferred to 25 Balb/c mice. Further 15 control mice were injected with phosphate-buffered saline and 9 mice did not receive any injection. In all patients cardiac-specific AHA of IgG class had been previously detected by an indirect immunofluorescence (IFL) technique on cryostat sections of O blood group human heart. The animals were sacrificed after 4 weeks and the hearts were blindly examined for histological evidence of myocarditis by an expert cardiac pathologist. RESULTS: Myocarditis was present in 13/25 (52%) of the mice which received affinity-purified IgG from patients. The findings of severe, moderate or mild myocarditis were more common in the mice which received affinity-purified IgG from patients (20%; 20% and 12%) than in control animals (2%, p=0.01; 0%, p=0.003; and 0%, p=0.04 respectively). CONCLUSIONS: These findings provide a new evidence for AHA-mediated pathogenicity in human myocarditis, according to Rose-Witebsky criteria.