Harmonic balance surrogate-based immunity modeling of a nonlinear analog circuit

A novel harmonic balance surrogate-based technique to create fast and accurate behavioral models predicting, in the early design stage, the performance of nonlinear analog devices during immunity tests is presented. The obtained immunity model hides the real netlist, reduces the simulation time, and avoids expensive and time-consuming measurements after tape-out, while still providing high accuracy. The model can easily be integrated into a circuit simulator together with additional subcircuits, e.g., board and package models, as such allowing to efficiently reproduce complete immunity test setups during the early design stage and without disclosing any intellectual property. The novel method is validated by means of application to an industrial case study, being an automotive voltage regulator, clearly showing the technique's capabilities and practical advantages

Effect of fetal breathing movements on fetal cardiac hemodynamics

__Abstract__ Maximum flow velocity waveforms were studied at atrioventricular and outflow tract level in 12 cases during fetal breathing activity and in 12 cases during fetal apnea matched for maternal and gestational age and maternal parity. Gestational age ranged between 27 and 40 weeks (median 30 weeks). All flow velocity waveforms were obtained using a mechanical sector scanner with a pulsed Doppler system (carrier frequency 3.5 MHz). Time-averaged flow velocities were clearly different between inspiration and expiration at all four recording levels, reflecting changes in venous return as a result of fluctuations in intrathoracic pressure during fetal breathing activity. Percentage change between inspiration and expiration at outflow tract level was positively correlated with gestational age. Time-averaged flow velocity at mitral level and ascending aorta level was significantly higher during fetal breathing activity than during apnea, suggesting increased shunting of blood flow through the foramen ovale. Acceleration time at outflow tract level demonstrated very little change relative to inspiration and expiration

Inappropriate Implantable Cardioverter-Defibrillator Shocks Incidence, Predictors, and Impact on Mortality

ObjectivesThe purpose of this study was to assess the incidence, predictors, and outcome of inappropriate shocks in implantable cardioverter-defibrillator (ICD) patients.BackgroundDespite the benefits of ICD therapy, inappropriate defibrillator shocks continue to be a significant drawback. The prognostic importance of inappropriate shocks outside the setting of a clinical trial remains unclear.MethodsFrom 1996 to 2006, all recipients of defibrillator devices equipped with intracardiac electrogram storage were included in the current analysis and clinically assessed at implantation. During follow-up, the occurrence of inappropriate ICD shocks and all-cause mortality was noted.ResultsA total of 1,544 ICD patients (79% male, age 61 ± 13 years) were included in the analysis. During the follow-up period of 41 ± 18 months, 13% experienced ≥1 inappropriate shocks. The cumulative incidence steadily increased to 18% at 5-year follow-up. Independent predictors of the occurrence of inappropriate shocks included a history of atrial fibrillation (hazard ratio [HR]: 2.0, p < 0.01) and age younger than 70 years (HR: 1.8, p = 0.01). Experiencing a single inappropriate shock resulted in an increased risk of all-cause mortality (HR: 1.6, p = 0.01). Mortality risk increased with every subsequent shock, up to an HR of 3.7 after 5 inappropriate shocks.ConclusionsIn a large cohort of ICD patients, inappropriate shocks were common. The most important finding is the association between inappropriate shocks and mortality, independent of interim appropriate shocks

European regulatory agenices should employ full time statisticians

No abstract available

Body-fat indicators and kidney function decline in older post-myocardial infarction patients: The Alpha Omega Cohort Study

Clinical epidemiolog

Body-fat indicators and kidney function decline in older post-myocardial infarction patients:The Alpha Omega Cohort Study

Background: Obesity increases risk of hypertension and diabetes, the leading causes of end-stage renal disease. The effect of obesity on kidney function decline in stable post-myocardial infarction patients is poorly documented. This relation was investigated in a large cohort of older post-myocardial infarction patients. Design: Data were analysed from 2410 post-myocardial infarction patients in the Alpha Omega Trial, aged 60–80 years receiving optimal pharmacotherapy treatment (79% men, 18% diabetes). Methods: Cystatin C based estimated glomerular filtration rate (eGFRcysC) was calculated at baseline and after 41 months, using the Chronic Kidney Disease Epidemiology Collaboration (CKD-EPI) equation. Obesity was defined as body mass index ≥ 30 kg/m2 and high waist circumference as ≥102 and ≥88 cm for men and women. The relation between body mass index, waist circumference and annual eGFRcysC decline was evaluated by linear regression. Results: At baseline, mean (standard deviation) eGFRcysC was 81.5 (19.6) ml/min/1.73 m2, 23% of all patients were obese. After multivariable adjustment, the annual mean (95% confidence interval) eGFRcysC decline in men and women was –1.45 (–1.59 to –1.31) and –0.92 (–1.20 to –0.63) ml/min/1.73 m2, respectively (p = 0.001). Obese versus non-obese patients and patients with high versus normal waist circumference experienced greater annual eGFRcysC decline. Men and women showed an additional annual eGFRcysC decline of –0.35 (–0.56 to –0.14) and –0.21 (–0.55 to 0.14) ml/min/1.73 m2 per 5 kg/m2 body mass index increment (p for interaction 0.3). Conclusions: High compared to normal body mass index or waist circumference were associated with more rapid kidney function decline in older stable post-myocardial infarction patients receiving optimal drug therapy.</p

Investigating Feedback on Practice Among Teachers: Coherence of Observed and Perceived Feedback

Despite that benefits of feedback in student learning are reported in much research, little has been reported regarding the use of feedback from teach- ers to other teachers—a key tool in professional development. In this study, we triangulated data from videotaped peer coaching sessions, ques- tionnaires, and interviews regarding 12 primary school teachers in four peer groups in the Netherlands. We focused our research on two issues: the interplay of observed feedback dimensions and elements and perceptions of that feedback. Feedback dimensions were generally effective and the influence of the elements on the dimensions mostly aligned with the expectations. Teachers generally perceived feedback as effective. More- over, effective observed feedback was perceived as effective. Findings indicate that peer coaches should stimulate coached teachers to become goal directed, specific, detailed, and neutral (neither positive nor negative) by using feedback elements so as to optimize feedback processes

Meta-analysis of binary outcomes via generalized linear mixed models: a simulation study

Background: Systematic reviews and meta-analyses of binary outcomes are widespread in all areas of application. The odds ratio, in particular, is by far the most popular effect measure. However, the standard meta-analysis of odds ratios using a random-effects model has a number of potential problems. An attractive alternative approach for the meta-analysis of binary outcomes uses a class of generalized linear mixed models (GLMMs). GLMMs are believed to overcome the problems of the standard random-effects model because they use a correct binomial-normal likelihood. However, this belief is based on theoretical considerations, and no sufficient simulations have assessed the performance of GLMMs in meta-analysis. This gap may be due to the computational complexity of these models and the resulting considerable time requirements. Methods: The present study is the first to provide extensive simulations on the performance of four GLMM methods (models with fixed and random study effects and two conditional methods) for meta-analysis of odds ratios in comparison to the standard random effects model. Results: In our simulations, the hypergeometric-normal model provided less biased estimation of the heterogeneity variance than the standard random-effects meta-analysis using the restricted maximum likelihood (REML) estimation when the data were sparse, but the REML method performed similarly for the point estimation of the odds ratio, and better for the interval estimation. Conclusions: It is difficult to recommend the use of GLMMs in the practice of meta-analysis. The problem of finding uniformly good methods of the meta-analysis for binary outcomes is still open