Impact of a Multifaceted Early Mobility Intervention for Critically Ill Children - the PICU Up! Trial: Study Protocol for a Multicenter Stepped-Wedge Cluster Randomized Controlled Trial

BACKGROUND: Over 50% of all critically ill children develop preventable intensive care unit-acquired morbidity. Early and progressive mobility is associated with improved outcomes in critically ill adults including shortened duration of mechanical ventilation and improved muscle strength. However, the clinical effectiveness of early and progressive mobility in the pediatric intensive care unit has never been rigorously studied. The objective of the study is to evaluate if the PICU Up! intervention, delivered in real-world conditions, decreases mechanical ventilation duration (primary outcome) and improves delirium and functional status compared to usual care in critically ill children. Additionally, the study aims to identify factors associated with reliable PICU Up! delivery. METHODS: The PICU Up! trial is a stepped-wedge, cluster-randomized trial of a pragmatic, interprofessional, and multifaceted early mobility intervention (PICU Up!) conducted in 10 pediatric intensive care units (PICUs). The trial\u27s primary outcome is days alive free of mechanical ventilation (through day 21). Secondary outcomes include days alive and delirium- and coma-free (ADCF), days alive and coma-free (ACF), days alive, as well as functional status at the earlier of PICU discharge or day 21. Over a 2-year period, data will be collected on 1,440 PICU patients. The study includes an embedded process evaluation to identify factors associated with reliable PICU Up! delivery. DISCUSSION: This study will examine whether a multifaceted strategy to optimize early mobility affects the duration of mechanical ventilation, delirium incidence, and functional outcomes in critically ill children. This study will provide new and important evidence on ways to optimize short and long-term outcomes for pediatric patients. TRIAL REGISTRATION: ClinicalTrials.gov NCT04989790. Registered on August 4, 2021

Computational Homogenization of Architectured Materials

Architectured materials involve geometrically engineered distributions of microstructural phases at a scale comparable to the scale of the component, thus calling for new models in order to determine the effective properties of materials. The present chapter aims at providing such models, in the case of mechanical properties. As a matter of fact, one engineering challenge is to predict the effective properties of such materials; computational homogenization using finite element analysis is a powerful tool to do so. Homogenized behavior of architectured materials can thus be used in large structural computations, hence enabling the dissemination of architectured materials in the industry. Furthermore, computational homogenization is the basis for computational topology optimization which will give rise to the next generation of architectured materials. This chapter covers the computational homogenization of periodic architectured materials in elasticity and plasticity, as well as the homogenization and representativity of random architectured materials

Wave propagation in random fiberous networks

Random fiberous networks are ubiquitous in different length scales with a broad range of applications including biological tissues, paper, polymer transistors, protective clothing and packaging materials. Given the importance of fiber networks, their static behavior has been extensively studied and it has been shown that network deformation is nonaffine for compliant, low-density networks and affine for stiff, high-density networks. However, little is known about the dynamic response of fibrous systems. In this study, we investigated numerically the propagation of small-amplitude elastic waves in these random networks and characterize their dynamic response as a function of network parameters. Interestingly, our numerical analysis revealed that the low-frequency response of these fiberous networks is highly affected not only by the network parameters, but also by the wavelength of the propagating waves

Dynamics below the depinning transition of interacting dislocations moving over fields of obstacles

International audienceThe transition from the behavior of a single dislocation interacting with a field of fixed obstacles to the collective motion of multiple dislocations is studied below the depinning transition (thermally activated glide). In absence of interactions, a truncated power law distribution of jump amplitudes (avalanches) with a diverging cutoff toward the critical point, and intermittency are observed. Interactions lead to a modification of the correlation length exponent below the critical point and to more pronounced intermittency, a dynamics more compatible to acoustic emission experimental data

Aluminum Alloys with Identical Plastic Flow and Different Strain Rate Sensitivity

WOS: 000283943900012Mg-rich and Si-rich aluminum alloys from the AA6XXX class are considered to demonstrate that standard heat treatments can be used to produce materials with identical plastic flow (yield stress and strain hardening) and different strain rate sensitivity. The Mg-rich alloy exhibits lower strain rate sensitivity and a different variation of this parameter with the stress (Haasen plot) relative to the Si-rich alloy. This is due to the instantaneous component of the strain rate sensitivity being smaller in the Mg-rich alloy. Hence, the underlying mechanism is not related to the presence of free, fast diffusing Mg atoms, but rather to the different nature of precipitates forming in the two alloys. A simple model is used to demonstrate that it is possible to tailor the strain rate sensitivity while preserving the flow stress by controlling the nature of precipitates and that of the dislocation-precipitate interaction