[Adjustment of healthcare and telemedicine in times of lockdown and COVID-19 pandemic: Feedback from a "Maison des Adolescents" (Teenager's House)]. / Adaptation des soins et télémédecine en période de confinement et de pandémie de COVID-19 : retour d'expérience d'une Maison des Adolescents.

BACKGROUND: The COVID-19 sanitary crisis has imposed a major reorganization of the health care system in France. Lockdown could be a factor in the emergence or deterioration of psychological disorders; it can be even more fragilizing during the specific period of adolescence. The « Maisons des Adolescents ¼ (Teenagers' Houses) had to urgently adjust their practices to provide continuity of care for adolescents suffering from physical or mental disorders. The « Maisons des Adolescents ¼ are pluridisciplinary care centres for adolescents and their families that provide assessments and services for medical, psychological, socio-educational, educational and legal needs. How did care continue for adolescents during lockdown? What adjustments occurred in the « Maisons des Adolescents ¼ during the health crisis? METHODS: This article presents the case of an adolescent who suffered a significant deterioration of her anorexia nervosa during confinement. Through this case, we describe the reorganization of care within the different units (consultations - day hospital - hospitalization unit) of a Parisian « Maison des Adolescents ¼ during the COVID-19 pandemic. FINDINGS: In this service, the rapid implementation of the telemedicine system in the context of the COVID-19 pandemic made possible provision of continuity in care for vulnerable adolescents and families. Based on the existing literature, we discuss the advantages and limitations of telemedicine and the practical issues for the future organization of care for adolescents. PERSPECTIVES: In contrast to pediatric medicine or child psychiatry, there is no protocol describing the application of telemedicine in adolescent medicine and psychiatry. There is an urgent need for further evaluation of the use of telemedicine for this population. This kind of research will improve knowledge about the effectiveness, acceptability and limitations of using a teleconsultation device in adolescent psychiatry in a crisis context. Certain remote care modalities implemented during the sanitary crisis could thus be maintained over time and become routine in the field of adolescent medicine and psychiatry.

A comparative study on Monte Carlo simulations of electron emission from liquid water.

PURPOSE: Liquid water being the major constituent of the human body, is of fundamental importance in radiobiological research. Hence, the knowledge of electron-water interaction physics and particularly the secondary electron yield is essential. However, to date, only very little is known experimentally on the low energy electron interaction with liquid water because of certain practical limitations. The purpose of this study was to gain some useful information about electron emission from water using a Monte Carlo (MC) simulation technique that can numerically model electron transport trajectories in water. METHODS: In this study, we have performed MC simulations of electron emission from liquid water in the primary energy range of 50 eV-30 keV by using two different codes, i.e., a classical trajectory MC (CMC) code developed in our laboratory and the Geant4-DNA (G4DNA) code. The calculated secondary electron yield and electron backscattering coefficient are compared with experimental results wherever applicable to verify the validity of physical models for the electron-water interaction. RESULTS: The secondary electron yield vs. primary energy curves calculated using the two codes present the same generic curve shape as that of metals but in rather different absolute values. G4DNA underestimates the secondary electron yield due to the application of one step thermalization model by setting a cutoff energy at 10 eV so that the low energy losses due to phonon excitations are omitted. Our CMC code, using a full energy loss spectrum to model electron inelastic scattering, allows the simulation of individual phonon scattering events for very low energy losses down to 10 meV, which then enables the calculated secondary electron yields much closer to the experimental data and also gives quite reasonable energy distribution curve of secondary electrons. CONCLUSIONS: It is concluded that full dielectric function data at low energy loss values below 10 eV are recommended for modeling of low energy electrons in liquid water.

Influence of neutral beam attenuation on beam emission spectroscopy and charge exchange recombination spectroscopy.

Neutral beam attenuation is simulated by means of consulting the ADAS (Atomic Data and Analysis Structure) database based on experimentally diagnosed radial plasma density and electron temperature profiles on the Experimental Advanced Superconducting Tokamak (EAST). Two-dimensional distributions of beam emission and charge exchange recombination photon flux are simulated, taking neutral beam attenuation into account, together with comparison with experimental results of Beam Emission Spectroscopy (BES) and Charge eXchange Recombination Spectroscopy (CXRS). A photon number which is over 1014 promises a sufficient photon flux for typical detectors of BES, CXRS, and UltraFast-CXRS (UF-CXRS) diagnostics. Evidence shows that the ADAS database overvalues neutral beam injection effective stopping coefficient on the EAST tokamak. The joint diagnostic of BES and UF-CXRS which is under development to measure plasma pressure with a high temporal resolution of 1 µs will have strong signals in a radial range of 0.6 < ρ < 0.8. The steep gradients of plasma density and C6+ density at ρ ∼ 1 bring great difficulty to edge plasma investigation by this joint diagnostic.

Quantum-trajectory Monte Carlo method for study of electron-crystal interaction in STEM.

In this paper, a novel quantum-trajectory Monte Carlo simulation method is developed to study electron beam interaction with a crystalline solid for application to electron microscopy and spectroscopy. The method combines the Bohmian quantum trajectory method, which treats electron elastic scattering and diffraction in a crystal, with a Monte Carlo sampling of electron inelastic scattering events along quantum trajectory paths. We study in this work the electron scattering and secondary electron generation process in crystals for a focused incident electron beam, leading to understanding of the imaging mechanism behind the atomic resolution secondary electron image that has been recently achieved in experiment with a scanning transmission electron microscope. According to this method, the Bohmian quantum trajectories have been calculated at first through a wave function obtained via a numerical solution of the time-dependent Schrödinger equation with a multislice method. The impact parameter-dependent inner-shell excitation cross section then enables the Monte Carlo sampling of ionization events produced by incident electron trajectories travelling along atom columns for excitation of high energy knock-on secondary electrons. Following cascade production, transportation and emission processes of true secondary electrons of very low energies are traced by a conventional Monte Carlo simulation method to present image signals. Comparison of the simulated image for a Si(110) crystal with the experimental image indicates that the dominant mechanism of atomic resolution of secondary electron image is the inner-shell ionization events generated by a high-energy electron beam.

Monte Carlo simulation of secondary electron images for real sample structures in scanning electron microscopy.

Monte Carlo simulation methods for the study of electron beam interaction with solids have been mostly concerned with specimens of simple geometry. In this article, we propose a simulation algorithm for treating arbitrary complex structures in a real sample. The method is based on a finite element triangular mesh modeling of sample geometry and a space subdivision for accelerating simulation. Simulation of secondary electron image in scanning electron microscopy has been performed for gold particles on a carbon substrate. Comparison of the simulation result with an experiment image confirms that this method is effective to model complex morphology of a real sample.

Validity of the semi-classical approach for calculation of the surface excitation parameter.

The problem of surface plasmon excitation by moving charges has been elaborated by several different approaches, mainly based on dielectric response theory within either semi-classical or quantum mechanical frameworks. In this work, a comparison of the surface excitation effect between two different frameworks is made by calculation of the differential inverse inelastic mean free path (DIIMFP) and a Monte Carlo simulation of reflection electron energy loss spectroscopy (REELS) spectra. A semi-classical modeling of the interaction between electrons and a solid surface is based on analyzing the work done by moving electrons; the stopping power and inelastic cross section are derived with the induced potential. On the other hand, a quantum mechanical approach is based on derivation of the complex inhomogeneous self-energy of the electrons. The numerical calculation shows that the semi-classical model presents almost the same values of DIIMFP as by the quantum model except at the glancing condition. The simulation of REELS spectra for Ag and SiO(2) as well as a comparison with experimental spectra also confirms that a good agreement with the spectral shape is found among the two simulation results and the experimental data.

Monte Carlo simulation of dopant contrast in scanning electron microscope image.

In this work, the dopant contrast in SEM image between the p-type and n-type areas in the semiconductor device is studied by using a Monte Carlo simulation method. The work function induced by the surface state is considered to be responsible for the dopant contrast. A layer-by-layer structure, i.e., three p-type layers with different concentrations and one n-type layer, each of them is separated by a undoped intrinsic Si layer, has been simulated to compare with the experimental observation. The simulated image shows clearly a dopant contrast between the layers and the undopted Si substrate.