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SHARP RESOLVENT ESTIMATE FOR THE DAMPED-WAVE BAOUENDI-GRUSHIN OPERATOR AND APPLICATIONS
No full textIn this article we study the semiclassical resolvent estimate for the non-selfadjoint Baouendi-Grushin operator on the two-dimensional torus T 2 = R 2 /(2πZ) 2 with Hölder dampings. The operator is subelliptic degenerating along the vertical direction at x = 0. We exhibit three different situations: (i) the damping region verifies the geometric control condition with respect to both the non-degenerate Hamiltonian flow and the vertical subelliptic flow; (ii) the undamped region contains a horizontal strip; (iii) the undamped part is a line. In all of these situations, we obtain sharp resolvent estimates. Consequently, we prove the optimal energy decay rate for the associated damped waved equations. For (i) and (iii), our results are in sharp contrast to the Laplace resolvent since the optimal bound is governed by the quasimodes in the subelliptic regime. While for (ii), the optimality is governed by the quasimodes in the elliptic regime, and the optimal energy decay rate is the same as for the classical damped wave equation on T 2. Our analysis contains the study of adapted two-microlocal semiclassical measures, construction of quasimodes and refined Birkhoff normal-form reductions in different regions of the phase-space. Of independent interest, we also obtain the propagation theorem for semiclassical measures of quasimodes microlocalized in the subelliptic regime
Catherine de Médicis, figure miroir des Mémoires de Marguerite de Valois
No full textInternational audienc
Tsunami hazard along the Alboran Coast triggered by submarine landslides
No full textInternational audienceHistorical earthquake records suggest that the Alboran Sea seismicity is mostly triggered by strike-slip faults with little or no vertical throw preventing significant tsunami formation. Although in the North Alboran Sea the Averroes fault may have a tsunamigenic potential, the main active fault system responsible of the last three major earthquakes (Mw &#8805; 6) in the South Alboran Sea, the Al-Idrissi fault, has no significant vertical component. This points to submarine landslides as the main potential source of tsunamis for the southern sector of the basin. Our study deals with the tsunamigenic potential of submarine landslides in the southern Alboran Sea, where several deposits are stacked within the last million year of sedimentary cover. We have identified up to 67 landslide events with volumes between 0.01 to 15 km<sup>3</sup>. The probability of landslide occurrence has been analysed with a logistic regression describing the relationship between a binary response variable (existence or absence of landslide) and a set of predictor variables such as high seafloor gradients and presence of active faults. The analysis of the severity of a given landslide has been investigated based on the estimation of the probability that the landslide reaches a certain (high) level (e.g. tsunami run-up or submarine cable breaks) giving that it has occurred through the extreme value analysis. We have used the Shaltop code simulating landslide run-out on the basis of a depth-averaged model based on the hydrostatic Saint Venant equations and Coulomb-type basal friction considering a Bingham rheology. Our tsunami simulations include Shaltop output scenarios as a source of the generated tsunami through hydrodynamic simulations using the hydrostatic 3D Navier-Stokes code Freshkiss3d. We found that tsunamis waves triggered by submarine landslides on the South Alboran Sea would be no higher than two meters. However, the tsunami would include wavelengths of tens of kilometres translating into important water volumes flooding several areas of around the Alboran coast
Deep-seated gravitational slope deformation and rock-slope failures deposits in Iceland: inventory, dating and role in landscape evolution
No full textInternational audienceFollowing the Last Glacial Maximum, icelandic hillslopes experienced a paraglacial crisis, which occurred between 15-10 ka BP. In the North, West and East parts of Iceland, in the high plateaus and slopes developed in the Tertiary basaltic formations, two types of paraglacial denudation features, deep-seated gravitational slope deformation (DSGSD) and rock-slope failure (RSF) deposits, are numerous.</p><p>An inventory and several maps of DSGSD and RSF are proposed at the scale of those three icelandic regions of Iceland. The mapping was made by combining aerial photographs, satellite images and field prospections. The DSGSD is characterized by typical ridge-top grabens, scarps and antiscarps associated with upslope and downslope dipping fractures along bulged upper slopes. The RSF could be identified by defining the crown and deposits. Both features could be analyzed by using direct observations and NDVI index from satellite images.An approach of the timing of the DSGSD and rock-slope failures settlement is also proposed in this contribution by using field investigations (geomorphological stacking, tephrochronology, radiocarbon dating of wood remains in depression on RSL deposits, and age-depth models). The genetic links between DSGSD and landslides, the effects of these paraglacial denudation dynamics on the evolution of landforms (cirques, valleys) are discussed. Furthermore, the erosion rates involved by such paraglacial crises (volumes of landslide deposits) are compared with erosion rates involved other processes on icelandic slopes during the Holocene. Finally, this paraglacial denudation crisis, illustrated by DSGSD and RSF, appears as the main sequence of icelandic landscape evolution since the last glaciation
The Hydration State of Bone Tissue Affects Contrast in Neutron Tomographic Images
No full textInternational audienceNeutron tomography has emerged as a promising imaging technique for specific applications in bone research. Neutrons have a strong interaction with hydrogen, which is abundant in biological tissues, and they can penetrate through dense materials such as metallic implants. However, in addition to long imaging times, two factors have led to challenges in running in situ mechanical characterization experiments on bone tissue using neutron tomography: 1) the high water content in specimens reduces the visibility of internal trabecular structures; 2) the mechanical properties of bone are dependent on the hydration state of the tissue, with drying being reported to cause increased stiffness and brittleness. This study investigates the possibility of improving image quality in terms of neutron transmission and contrast between material phases by drying and rehydrating in heavy water. Rat tibiae and trabecular bovine bone plugs were imaged with neutron tomography at different hydration states and mechanical testing of the bone plugs was carried out to assess effects of drying and rehydration on the mechanical properties of bone. From analysis of image histograms, it was found that drying reduced the contrast between bone and soft tissue, but the contrast was restored with rehydration. Contrast-to-noise ratios and line profiles revealed that the contrast between bone tissue and background was reduced with increasing rehydration duration but remained sufficient for identifying internal structures as long as no free liquid was present inside the specimen. The mechanical analysis indicated that the proposed fluid exchange protocol had no adverse effects on the mechanical properties
Improving efficacy of aphasia rehabilitation by using Core Assessment of Language Processing
No full textInternational audienceNo abstract availabl
Women Directors on Traditionally Male-Dominated Stock Exchange Boards: Can They Make a Difference?
No full textInternational audienc
Odor background increases pheromone coding efficiency in moth olfactory neurons
No full textInternational audienc
Occupational disruptions during lockdown, by generation: A European descriptive cross-sectional survey
No full textInternational audienceIntroduction The periods of lockdown during 2020 led to changes in daily occupations. As participation relies on dynamic interactions between the person, his/her occupations and his/her environment, we wondered whether people from different generations shared the same perception of occupational disruptions during the lockdown.Methods We performed an online survey based on the Canadian Occupational Performance Measure (COPM) of adults in 27 European Union countries, the United Kingdom and Switzerland. Three groups were compared: young adults (YAs, aged 18–39), middle-aged adults (MAs, aged 40–59) and older adults (OAs, aged 60 and over).Results 2865 participants (YAs: 47%; MAs: 33%; OAs: 20%) reported a total of 6549 disrupted occupations. The most frequently disrupted domain was leisure (83%), followed by productivity (16%) and self-care (2%); there were no significant intergroup differences ( p = 0.18). In a multivariate analysis, socializing disruptions were more likely to be associated with younger age (adjusted odds ratio (OR) [95% confidence interval (CI)] = 0.62 [0.50–0.76] for YAs versus MAs and 0.46 [0.30–0.71] for YAs versus OAs.Conclusion With the exception of socializing, the main disrupted occupations were similar from one generation to another. Our findings might enable the more accurate assessment of the risk of occupational disruption in a restrictive environment
Effectiveness of Geriatric Assessment-Driven Interventions on Survival and Functional and Nutritional Status in Older Patients with Head and Neck Cancer: A Randomized Controlled Trial (EGeSOR)
No full textInternational audienceThis study assesses the efficacy of Geriatric Assessment (GA)-driven interventions and follow-up on six-month mortality, functional, and nutritional status in older patients with head and neck cancer (HNC). HNC patients aged 65 years or over were included between November 2013 and September 2018 by 15 Ear, Nose, and Throat (ENT) and maxillofacial surgery departments at 13 centers in France. The study was of an open-label, multicenter, randomized, controlled, and parallel-group design, with independent outcome assessments. The patients were randomized 1:1 to benefit from GA-driven interventions and follow-up versus standard of care. The interventions consisted in a pre-therapeutic GA, a standardized geriatric intervention, and follow-up, tailored to the cancer-treatment plan for 24 months. The primary outcome was a composite criterion including six-month mortality, functional impairment (fall in the Activities of Daily Living (ADL) score ≥2), and weight loss ≥10%. Among the patients included (n = 499), 475 were randomized to the experimental (n = 238) or control arm (n = 237). The median age was 75.3 years [70.4–81.9]; 69.5% were men, and the principal tumor site was oral cavity (43.9%). There were no statistically significant differences regarding the primary endpoint (n = 98 events; 41.0% in the experimental arm versus 90 (38.0%); p = 0.53), or for each criterion (i.e., death (31 (13%) versus 27 (11.4%); p = 0.48), weight loss of ≥10% (69 (29%) versus 65 (27.4%); p = 0.73) and fall in ADL score ≥2 (9 (3.8%) versus 13 (5.5%); p = 0.35)). In older patients with HNC, GA-driven interventions and follow-up failed to improve six-month overall survival, functional, and nutritional status