ESEO Group

The management of system complexity is essential to ensure the successful delivery of a system. However, as system complexity continues to grow, an accurate quantitative measure of the complexity of a system becomes a necessity. In this study, we consider the definition of structural complexity introduced by Sinha, and we derive analytical expressions for the complexity of both individual components alone and their interactions. Among the complexity metrics developed to date, we considered entropy-based ones, which allowed us to objectively quantify the complexity while satisfying the criteria introduced by Weyuker. The notion of intrinsic descriptive complexity introduced by Kolmogorov, instead of the Shannon entropy, was used to analyze the structural complexity of engineered systems. The applicability of the structural complexity metric to the graph representing the system architecture is demonstrated.

Rationale: It is currently unclear which patients with obstructive sleep apnea (OSA) are at increased cardiovascular risk. Objective: To investigate the value of pulse wave amplitude drops (PWAD), reflecting sympathetic activations and vasoreactivity, as a biomarker of cardiovascular risk in OSA. Materials and methods: PWAD was derived from pulse oximetry-based photoplethysmography signal in three prospective cohorts: HypnoLaus (N=1941), Pays-de-la-Loire Sleep Cohort (PLSC; N=6367) and ISAACC (N=692). PWAD index was the number of PWAD (>30%) per hour during sleep. All participants were divided into subgroups according to the presence/absence of OSA (apnea-hypopnea index [AHI]≥15 or <15/hours) and the median PWAD index. Primary outcome was the incidence of composite cardiovascular events. Results: Using Cox models adjusted for cardiovascular risk factors (hazard ratio [95% confidence interval]), patients with low PWAD index and OSA had a higher incidence of cardiovascular events versus the high PWAD/OSA group and those without OSA in HypnoLaus (2.16[1.07-4.34], p=0.031 and 2.35[1.12-4.93], p=0.024) and PLSC (1.36[1.13-1.63], p=0.001 and 1.44[1.06-1.94], p=0.019), respectively. In ISAACC, the low PWAD/OSA untreated group had a higher cardiovascular event recurrence rate versus the no-OSA group (2.03[1.08-3.81], p=0.028). In PLSC and HypnoLaus, every 10 events/h increase in continuous PWAD index was independently associated with incident cardiovascular events exclusively in OSA patients (HR 0.85[0.73-0.99], p=0.031 and HR 0.91[0.86-0.96], p=<0.001 respectively). This association were not significant in no-OSA and in ISAACC. Conclusions: In OSA patients, a low PWAD index reflecting poor autonomic and vascular reactivity was independently associated with a higher cardiovascular risk.

Transfer impedance is a main characteristic to describe the shielding performance of shielded cables at least up to 1 GHz. Traditionally, methods, such as line-injection and triaxial cell, have been used to characterize it at ambient laboratory conditions. While the ambient laboratory conditions might represent appropriate environmental conditions for some industries, in others, such as automotive, they are only a small subset of the real conditions. Thus, there is a need to characterize the transfer impedance over different environmental conditions. In this article, the authors present and verify a new triaxial cell design that is aimed to provide reliable measurements during high thermal and mechanical stresses. First, the cell performance is compared with a commercial cell at laboratory ambient conditions. Then, measurements are performed with the new cell at highly accelerated life testing conditions. Under these high thermal and mechanical stress conditions, the cell performance is verified, and results on typical shielded cable performance under the same conditions are given.

Background: Previous studies have reported inconsistent findings regarding the association between obstructive sleep apnea (OSA) and incident venous thromboembolism (VTE). More specifically, the association between OSA and unprovoked VTE was barely evaluated. We aimed to evaluate whether apnea hypopnea index (AHI) and nocturnal hypoxemia markers were associated with unprovoked VTE incidence in patients investigated for OSA. Study design and methods: Data from the Pays de la Loire sleep cohort were linked to the French health administrative data to identify incident unprovoked VTE in patients suspected for OSA and no previous VTE disease. Cox proportional hazards models were used to evaluate the association of unprovoked VTE incidence with AHI and nocturnal hypoxemia markers including the time spend under 90% of saturation (T90), oxygen desaturation index and hypoxic burden (HB), a more specific marker of respiratory events related hypoxia. The impact of Continuous positive airway pressure (CPAP) was evaluated in the subgroup of patients who were proposed the treatment. Results: After a median [inter-quartile range] follow-up of 6.3 [4.3-9.0] years, 104 of 7,355 patients developed unprovoked VTE, for an incidence rate of 10.8 per 1,000 patient-year. In a univariate analysis, T90 and HB predicted incident VTE. In the fully adjusted model, T90 was the only independent predictor (HR 1.06; 95%CI [1.01-1.02]; p=0.02). The CPAP treatment has no significant impact on VTE incidence. Interpretation: Patients with more severe nocturnal hypoxia are more likely to have incident unprovoked VTE.

This letter comments on the letter by Abdulghani Sankari