Institut Universitaire de France

About: Institut Universitaire de France is a education organization based out in Paris, France. It is known for research contribution in the topics: Population & Catalysis. The organization has 1905 authors who have published 9042 publications receiving 309878 citations.

High depression and anxiety in people with Alzheimer's disease living in retirement homes during the covid-19 crisis.

Abstract: To cope with Covid-19 and limits its spread among residents, retirement homes have prohibited physical contact between residents and families and friend and, in some cases, even between residents or between residents and caregivers. We investigated the effects of measures against Covid-19 on the mental health of participants with Alzheimer's disease (AD) who live in retirement homes in France. We instructed on-site caregivers to assess depression and anxiety in participants with mild AD who live in retirement homes. Fifty-eight participants consented to participate in the study. The participants rated their depression and anxiety during and before the Covid-19 crisis. Participants reported higher depression (p = .005) and anxiety (p = .004) during than before the Covid-19 crisis. These increases can be attributed to the isolation of the residents and/or to the drastic changes in their daily life and care they receive. While, in their effort to prevent infections, retirement homes are forced to physically separate residents from the outside world and to drastically reduce residents' activities, these decisions are likely to come at a cost to residents with AD and their mental health.

In situ observations on the coupling between hydraulic diffusivity and displacements during fault reactivation in shales

Abstract: Key questions in fault reactivation in shales relate to the potential for enhanced fluid transport through previously low-permeability aseismic formations. Here we explore the behavior of a 20 m long N0-to-170°, 75-to-80°W fault in shales that is critically stressed under a strike-slip regime (σ1 = 4 ± 2 MPa, horizontal and N162° ± 15°E, σ2 = 3.8 ± 0.4 MPa and σ3 = 2.1 ± 1 MPa, respectively 7–8° inclined from vertical and horizontal and N72°). The fault was reactivated by fluid pressurization in a borehole using a straddle packer system isolating a 2.4 m long injection chamber oriented-subnormal to the fault surface at a depth of 250 m. A three-dimensional displacement sensor attached across the fault allowed monitoring fault movements, injection pressure and flow rate. Pressurization induced a hydraulic diffusivity increase from ~2 × 10−9 to ~103 m2 s−1 associated with a complex three-dimensional fault movement. The shear (x-, z-) and fault-normal (y-) components (Ux, Uy, and Uz) = (44.0 × 10−6 m, 10.5 × 10−6 m, and 20.0 × 10−6 m) are characterized by much larger shear displacements than the normal opening. Numerical analyses of the experiment show that the fault permeability evolution is controlled by the fault reactivation in shear related to Coulomb failure. The large additional fault hydraulic aperture for fluid flow is not reflected in the total normal displacement that showed a small partly contractile component. This suggests that complex dilatant effects estimated to occur in a plurimeter radius around the injection source affect the flow and slipping patch geometries during fault rupture, controlling the initial slow slip and the strong back slip of the fault following depressurization.

Theoretical H2CO emission from protostellar envelopes

Abstract: We present theoretical predictions of the formaldehyde emission from the envelopes of low mass protostars. The model accounts for the density profile across the envelope, assuming the Shu (1977) solution for the collapse,as well as for the gas temperature profile. The gas temperature is derived from the thermal balance according to the model previously developed by Ceccarelli et al. (1996). The formaldehyde abundance profile is approximated by a step function: in the outer envelope it is similar to that of molecular clouds, whereas in the inner envelope, where the dust temperature reaches the ice mantle evaporation temperature, it jumps to larger values. The results of the modeling for a 30 L ? source are reported for a large range of values of the formaldehyde abundance, both in the inner and outer envelope. Additional results for sources with different luminosities can be found in the web site www-laog.obs . uj f-grenoble. fr/∼ceccarel/mepew/mepew.html. They are meant to be directly used by the interested reader to estimate the two main parameters of the model: the inner and outer formaldehyde abundance. The model is applied to the observations of the well known low mass protostar IRAS 16293-2422 to illustrate the practical use of the diagnostic tools. Furthermore, we discuss how the observation of the H 1 2 2CO and H 1 3 2CO lines can in principle be used to discriminate between infalling and outflowing gas. Finally, the same web site hosts simpler non-LTE LVG predictions for a large range of densities, temperatures and column densities of several molecules. Again the goal of the web site is to provide users with easy to use theoretical predictions for a first assessement of expected and/or observed signals.

Fermi large area telescope study of cosmic rays and the interstellar medium in nearby molecular clouds

Abstract: We report an analysis of the interstellar γ -ray emission from the Chamaeleon, R Coronae Australis (R CrA), and Cepheus and Polaris flare regions with the Fermi Large Area Telescope. They are among the nearest molecular cloud complexes, within ∼300 pc from the solar system. The γ -ray emission produced by interactions of cosmic rays (CRs) and interstellar gas in those molecular clouds is useful to study the CR densities and distributions of molecular gas close to the solar system. The obtained γ -ray emissivities above 250 MeV are (5.9 ± 0.1stat +0.9 −1.0sys) × 10−27 photons s−1 sr−1 H-atom−1, (10.2 ± 0.4stat +1.2 −1.7sys) × 10−27 photons s−1 sr−1 H-atom−1, and (9.1 ± 0.3stat +1.5 −0.6sys) × 10−27 photons s−1 sr−1 H-atom−1 for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively. Whereas the energy dependences of the emissivities agree well with that predicted from direct CR observations at the Earth, the measured emissivities from 250 MeV to 10 GeV indicate a variation of the CR density by ∼20% in the neighborhood of the solar system, even if we consider systematic uncertainties. The molecular mass calibrating ratio, XCO = N(H2)/WCO, is found to be (0.96 ± 0.06stat +0.15 −0.12sys) × 1020 H2-molecule cm−2 (K km s−1)−1, (0.99 ± 0.08stat +0.18 −0.10sys) × 1020 H2-molecule cm−2 (K km s−1)−1, and (0.63 ± 0.02stat +0.09 −0.07sys) × 1020 H2-molecule cm−2 (K km s−1)−1 for the Chamaeleon, R CrA, and Cepheus and Polaris flare regions, respectively, suggesting a variation of XCO in the vicinity of the solar system. From the obtained values of XCO, the masses of molecular gas traced by WCO in the Chamaeleon, R CrA, and Cepheus and Polaris flare regions are estimated to be ∼5 × 103M , ∼103M , and ∼3.3 × 104M , respectively. A comparable amount of gas not traced well by standard Hi and CO surveys is found in the regions investigated.