Conception d'un amortisseur de vibrations magnétique à raideurs ajustables

National audienceThis study deals with the design of a magnetic vibration absorber. The vibrating magnetic mass is placed in a magnetic field created by fixed permanent magnets. The resulting linear and nonlinear stiffnesses can be controlled by adjusting the relative positions of the static magnets. The equations of the model of the damper are obtained using a multipole expansion. The proposed magnetic absorber can be used as a tuned mass damper, a nonlinear energy sink or a bi-stable vibration absorber. These 3 cases are experimentally observed using static force measurements.Cette étude porte sur la réalisation d'un amortisseur de vibrations constitué d'une masse oscillante magnétique placée dans un champ créé par des aimants statiques. En ajustant les positions de ces derniers, il est possible de contrôler les valeurs des raideurs linéaires et non linéaires afin de couvrir les cas d'un amortisseur à masse accordée, d'un puits d'énergie non linéaire et d'un amortisseur bi-stable. Une décomposition multipolaire permet d'établir une équation modèle pour le comportement de l'oscillateur magnétique. Une réalisation expérimentale permet d'observer les 3 configurations recherchées grâce à des mesures d'efforts statique

Conception d'un amortisseur de vibrations magnétiques à raideurs ajustables

Cette étude porte sur la réalisation d'un amortisseur de vibrations constitué d'une masse oscillante magnétique placée dans un champ créé par des aimants statiques. En ajustant les positions de ces derniers, il est possible de contrôler les valeurs des raideurs linéaires et non linéaires afin de couvrir les cas d'un amortisseur à masse accordée, d'un puits d'énergie non linéaire et d'un amortisseur bi-stable. Une décomposition multipolaire permet d'établir une équation modèle pour le comportement de l'oscillateur magnétique. Une réalisation expérimentale permet d'observer les 3 configurations recherchées grâce à des mesures d'efforts statique

Plant-dominated assemblage and invertebrates from the lower Cenomanian of Jaunay-Clan, western France

International audienceTwo fossil localities are reported on the "LGV SEA" railroad from the Lower Cenomanianof Jaunay-Clan (JC), near Poitiers, western France. The laminated mudstones yielded plantfossils including ferns (Cladophlebis, Osmundophyllum, Ruffordia goeppertii, Sphenopteris),conifers (Brachyphyllum, Dammarophyllum, Pagiophyllum), and terrestrial and aquaticfreshwater angiosperms (Eucalyptolaurus depreii, Ploufolia). They are associated with acoleopteran insect that shows systematic affinities to the modern subfamily Chrysomeli-nae (Chrysomelidae). This assemblage suggests connections with arborescent vegetationgrowing in calm freshwater environment. Brackish to marine invertebrates also occurand include a dakoticancroid crab (Brachyura, Podotremata, Dakoticancroidea) and a fewbivalves (Brachidontes). They suggest brackish episodes during pond sedimentation in acoastal environment. Lastly, vertebrates are represented by an isolated feather

Risk of intracranial haemorrhage and ischaemic stroke after convexity subarachnoid haemorrhage in cerebral amyloid angiopathy : international individual patient data pooled analysis

Altres ajuts: JF reports grants from Instituto de Salud Carlos III, grants from Fundació Marató TV3, grants from NIH, grants from Departament de Salut de la Generalitat de Catalunya.To investigate the frequency, time-course and predictors of intracerebral haemorrhage (ICH), recurrent convexity subarachnoid haemorrhage (cSAH), and ischemic stroke after cSAH associated with cerebral amyloid angiopathy (CAA). We performed a systematic review and international individual patient-data pooled analysis in patients with cSAH associated with probable or possible CAA diagnosed on baseline MRI using the modified Boston criteria. We used Cox proportional hazards models with a frailty term to account for between-cohort differences. We included 190 patients (mean age 74.5 years; 45.3% female) from 13 centers with 385 patient-years of follow-up (median 1.4 years). The risks of each outcome (per patient-year) were: ICH 13.2% (95% CI 9.9-17.4); recurrent cSAH 11.1% (95% CI 7.9-15.2); combined ICH, cSAH, or both 21.4% (95% CI 16.7-26.9), ischemic stroke 5.1% (95% CI 3.1-8) and death 8.3% (95% CI 5.6-11.8). In multivariable models, there is evidence that patients with probable CAA (compared to possible CAA) had a higher risk of ICH (HR 8.45, 95% CI 1.13-75.5, p = 0.02) and cSAH (HR 3.66, 95% CI 0.84-15.9, p = 0.08) but not ischemic stroke (HR 0.56, 95% CI 0.17-1.82, p = 0.33) or mortality (HR 0.54, 95% CI 0.16-1.78, p = 0.31). Patients with cSAH associated with probable or possible CAA have high risk of future ICH and recurrent cSAH. Convexity SAH associated with probable (vs possible) CAA is associated with increased risk of ICH, and cSAH but not ischemic stroke. Our data provide precise risk estimates for key vascular events after cSAH associated with CAA which can inform management decisions. The online version contains supplementary material available at 10.1007/s00415-021-10706-3

Function of the Retinal Pigment Epithelium in Patients With Neurofibromatosis Type 1

International audiencePURPOSE. Retinal and choroidal abnormalities in neurofibromatosis type 1 (NF1) remain poorly studied. It has been reported, however, that the function of the retinal pigment epithelium (RPE) in NF1 was abnormal, with a supra-normal Arden ratio of the electrooculogram (EOG). This study aims to evaluate the function of the RPE, using EOG, first in patients with NF1 compared to controls and second in patients with NF1 with choroidal abnormalities compared to patients with NF1 without choroidal abnormalities.METHODS. This prospective case-control study included 20 patients with NF1 (10 patients with choroidal abnormalities and 10 patients without) and 10 healthy patients, matched for age. A complete ophthalmologic assessment with multimodal imaging, an EOG, and a full-field electroretinogram were performed for each included patient. The main outcome measured was the EOG light peak (LP)/dark trough (DT) ratio.RESULTS. The LP/DT ratio was 3.02 ± 0.52 in patients with NF1 and 2.63 ± 0.31 in controls (P = 0.02). DT values were significantly lower in patients with NF1 than in controls (240 vs. 325 μV, P = 0.02), while light peak values were not significantly different (P = 0.26). No difference was found for peak latencies. No significant correlation between the surface and number of choroidal abnormalities and EOG parameters was demonstrated.CONCLUSIONS. This study confirms the dysfunction of the RPE in patients with NF1, involving a lower DT and a corresponding higher LP/DT ratio. We hypothesize that this pattern may be due to a dysregulation of the melanocytogenesis, inducing a disruption in Ca2 + ion flux and an abnormal polarization of the RPE

a New Reliable Boresight Calibration Method for Mobile Laser Scanning Applications

International audienceThis paper presents a new INS-LiDAR bore-sighting parameters calibration method that differs from traditional methods on two main aspects. First, the method is static, which avoids being affected by GPS errors and enables the extraction of scanlines. For terrestrial laser scanning, this aspect is extremely important since ranges are short and the GPS errors are the first source of error during the calibration process. Second, the method is based on a rigorous mathematical model, which allows providing reliable boresight quality factors. After presenting the boresight determination problem, this paper will introduce the existing calibration procedures. Then, it will describe the new procedure and explain how it overcomes the limitations of the traditional approaches. Finally, some results from both simulations and real datasets are presented to illustrate our approach

Efficacity of CT-guided intra-articular cervical facet steroid injection for cervical radiculopathy

Background: Traditionally, transforaminal steroid injection is performed in the management of cervical radiculopathy in medical failure treatment but carried a true risk of catastrophic complication. Another approach currently used is to perform intra-articular facet steroid injection to reach the epidural space. Purpose: The aim of this study was to describe the evolution of symptoms following intra-articular facet steroid injection in cervical radiculopathy. Material and methods: We conducted a retrospective study. We assessed all patients who had a CT-guided intra-articular facet steroid injection in our center (xx, xx, xx) from December 2015 to February 2021. Cervical MR pretherapeutic images were analyzed and classified according to cervical pain etiology: uncodiscarthrosis, disk herniation or congestive cervical posterior osteo-arthritis. All patients had clinical initial evaluation and then follow-up at 1 and 6 months. Pain severity was rated on a visual analog scale and expressed as a percentage of improvement. Results: Ninety-three patients were included. There were 56 patients with uncodiscarthrosis, 29 with a disk herniation and 8 with a cervical posterior congestive osteoarthritis. A significant improvement of the visual analog scale percentage was found for all patient at 1 and 6 months (p < 0.01). Visual analog scale percentage improvement was about 50 % for all etiologies. For all patients, no severe complications were reported. Conclusion: Intra-articular facet steroid injection may be considered for the treatment of cervical radiculopathy when other medical treatments have failed

Human seroreactivity distribution Venn diagrams.

<p>(A) Negative (−), simple, and multiple seropositive (+) sera for 828 sera investigated for MCPyV, PtvPyV1 and PtvPyV2. (B) Negative (−), simple and double seropositive (+) sample for the 300 sera investigated for TSPyV and OraPyV.</p

Phylogenetic relationships between human and closely related simian polyomaviruses based on VP1 protein.

<p>Human polyomaviruses are in black and simian polyomaviruses are in gray. Sequence accession numbers used are NC_001538 for BKPyV, NC_001699 for JCPyV, NC_009238 for KIPyV, NC_009539 for WuPyV, NC_010277 for MCPyV, NC_014406 for HPyV6, NC_014407 for HPyV7, NC_014361 for TSPyV, HQ696595 for HPyV9, NC_018102 for MWPyV, JX463183 for STLPyV, JX308829 for HPyV12, NC_001669 for SV40, NC_004763 for LPyV, AY691168 for ChPyV, HQ385747 for PtvPyV1b, HQ385750 for PtvPyV2c, FN356900 for OraPyV1 and FN356901 for OraPyV2.</p

Correlation between MCPyV and PtvPyV reactivity and between TSPyV and OraPyV1 reactivity.

<p>Correlation between ELISA reactivity of human serum samples against the different VLPs. Each point represents one serum sample. Correlation coefficients (Spearman) were determined using XLStat software.</p