The role of biomechanics in the assessment of carotid atherosclerosis severity: a numerical approach

Numerical fluid biomechanics has been proved to be an efficient tool for understanding vascular diseases including atherosclerosis. There are many evidences that atherosclerosis plaque formation and rupture are associated with blood flow behavior. In fact, zones of low wall shear stress are vivid areas of proliferation of atherosclerosis, and in particular, in the carotid artery. In this paper a model is presented for investigating how the presence of the plaque influences the distribution of the wall shear stress. In complement to a first approach with rigid walls, an FSI model is developed as well to simulate the coupling between the blood flow and the carotid artery deformation. The results show that the presence of the plaque causes an attenuation of the WSS in the after-plaque region as well as the emergence of recirculation areas

Geometry model for marker-based localisation

This work presents a novel approach for position estimation from monocularvision. It has been shown that vision systems have great capability in reaching precise and accurate measurements and are becoming the state-of-the-art innavigation. Navigation systems have only been integrated in commercial mobile robots since the early 2000s, and yet localisation in a dynamic environmentthat form the main building block of navigation, has no truly elegant solution.Solutions are many and their strategies and methods differ depending on theapplication. For the lack of a single accurate procedure, methods are combinedwhich make use of different sensors fusion. This thesis focus on the use of monocular vision sensor to develop an accurate Marker-Based positioning system thatcan be used in various applications in outdoor, in agriculture for example, andin other indoor applications. Many contributions arouse here in this context. Amain contribution is in perspective distortion correction in which distortions aremodeled in all its forms with correction process. This is essential when dealingwith measurements and shapes in images. Because of the lack of robustness indepth sensing using monocular vision-based system, a second contribution is inthe novel spherical marker-based approach position captured, which is designedand developed within the concept of relative pose estimation. In this Model-Basedposition estimation, relative position can be extracted instantaneously withoutthe need of prior knowledge of the previous state of the camera, as it relies onmonocular image. This model can as well compensate for the lack of knowledge inthe scale of the real world, for example in the case of Monocular Visual Simultaneous Localisation and Mapping (VSLAM). In addition to these contributions, someexperimental and simulation evidence presented in this work has shown feasibilityof the reading measurements like distance capture and relative pose between themarker-based model and the observer, with reliability and high accuracy. Thesystem has shown the ability to track accurately the object at a farthest possibleposition from low resolution digital images and from a single viewpoint. Whilethe main application field targeted is tracking mobile-robots, other applicationscan profit from this concept like motion capture and application related to thefield of topography

Characterization of the Mechanical Properties of the Human Aortic Arch Using an Expansion Method

Analyzing cardiovascular diseases leads to multidisciplinary problems which require transversal and complementary approaches. This study focuses on the identification of the mechanical properties of the aortic arch. Stereo-correlation technique is used to measure the strain field in the aortic arch during its expansion. The aorta is immersed in water which allows better results in terms of measurement method and to take into account the residual stress and strain effects. Results are obtained at different values of expansion: 9 samples are collected, 7 of them are frozen before the experiment and 2 are fresh. The mean age is 76 years old at the volunteers? time of death. 4 samples did not lead to conclusive results because of the quality of the arterial wall and leaks that happened during the experiment preventing a proper expansion. The horizontal and vertical displacements are relatively homogeneous for all the samples: two preferred radial and longitudinal directions are observed. The strain fields associated with these directions show heterogeneities and have significant differences between fresh and frozen specimen. The final objective is to perform virtual surgical simulation of the whole endovascular stent graft procedure for an aortic aneurysm. This procedure has a high rate of short-term success and its indication compared to open surgery is increasing but it needs to be more reliable and secure. In this context, it is important to identify the mechanical properties of the aorta for further numerical simulations

Role of the R349 Gene and Its Repeats in the MIMIVIRE Defense System

MIMIVIRE is a defense system described in lineage A Mimivirus (Mimiviridae family) that mediates resistance against Zamilon virophage. It is composed of putative helicase and nuclease associated with a gene of unknown function called R349, which contains four 15 bp repeats homologous to the virophage sequence. In a previous study, the silencing of such genes restored virophage susceptibility. Moreover, the CRISPR Cas-4 like activity of the nuclease has recently been characterized. In this study, a recently isolated Mimivirus of lineage A with R349 gene lacking 3 of 4 repeats was demonstrated to be susceptible to Zamilon. To reinforce the importance of the R349 gene in the MIMIVIRE system, we developed and presented, for the first time to our knowledge, a protocol for Mimivirus genomic editing. By knocking out R349 gene in a Mimivirus lineage A, we observed the replication of Zamilon, indicating that this gene is critical in the resistance against this specific group of virophages

The role of lubricant feeding conditions on the performance improvement and friction reduction of journal bearings

Most conventional hydrodynamic journal bearing performance tools can not suitably assess the effect of lubricant feeding conditions on bearing performance, even though these conditions are known to affect important performance parameters such as eccentricity and powerloss. A thermohydrodynamic analysis suitable to deal with realistic feeding conditions has been proposed. Special attention was given to the treatment of phenomena taking place within grooves and their vicinity,as well as to the ruptured film region. The effec to flubricant feeding pressure and temperature, groove length ratio,width ratio and number (single/twin) on bearing performance has been analyzed for a broad range of conditions.It was found that a careful tuning of the feeding conditions may indeed improve bearing performance.FCT - POCTI/EME/39202/200

A Real-World, Multicenter, Observational Retrospective Study of Durvalumab After Concomitant or Sequential Chemoradiation for Unresectable Stage III Non-Small Cell Lung Cancer

Introduction: For unresectable stage III non-small cell lung cancer (NSCLC), the standard therapy consists of chemoradiotherapy (CRT) followed by durvalumab maintenance for responding patients. The present study reports on the safety and outcome of durvalumab use after CRT in a real-world, multicenter, retrospective cohort. Methods: Two hundred thirty-eight patients have been included. We collected data on systemic therapy, radiation therapy, the timing between CRT and durvalumab, number of durvalumab cycles, reasons for non-starting or discontinuation, incidence and grade of adverse events (AEs), and progression-free survival (PFS) and overall survival (OS). Results: One hundred fifty-five patients out of 238 (65.1%) received at least one durvalumab dose: 91 (58.7%) after concomitant CRT (cCRT) and 64 (41.3%) after sequential CRT (sCRT). Programmed-death ligand 1 (PD-L1) status was unknown in 7/155 (4.5%), negative in 14 (9.1%), and positive ≥1% in 134/155 (86.4%). The main reasons for non-starting durvalumab were progression (10.1%), PD-L1 negativity (7.5%), and lung toxicity (4.6%). Median follow-up time was 14 months (range 2–29); 1-year PFS and OS were 83.5% (95%CI: 77.6–89.7) and 97.2% (95%CI: 94.6–99.9), respectively. No significant differences in PFS or OS were detected for cCRT vs. sCRT, but the median PFS was 13.5 months for sCRT vs. 23 months for cCRT. Potentially immune-related AEs were recorded in 76/155 patients (49.0%). Pneumonitis was the most frequent, leading to discontinuation in 11/155 patients (7.1%). Conclusions: Durvalumab maintenenace after concurrent or sequential chemoradiation for unresectable, stage III NSCLC showed very promising short-term survival results in a large, multicenter, restrospective, real-world study. Durvalumab was the first drug obtaining a survival benefit over CRT within the past two decades, and the present study contributes to validating its use in clinical practice