The Role of Coping in Processes of Resilience: The sample case of academic coping during late childhood and early adolescence

Developmentalists have increasingly concluded that systems approaches to resilience provide a useful higher-order home for the study of the development of coping. Building on previous work on the complementarity of resilience and coping, this paper had two goals: (1) to propose a set of strategies for examining the role of coping in processes of resilience, and (2) to test their utility in the academic domain, using poor relationships with the teacher as a risk factor, and classroom engagement as an outcome. This study examined whether coping serves as a: (1) promotive factor, supporting positive development at any level of risk; (2) pathway through which risk contributes to development; (3) protective factor that mitigates the effects of risk; (4) reciprocal process generating risk; (5) mechanism through which other promotive factors operate; (6) mechanism through which other protective factors operate; and (7) participant with other supports that shows cumulative or compensatory effects. Analyses showed that academic coping at this age was primarily a mediator of risk and support, and a promotive factor that added to engagement for students with multiple combinations of risk and support. Implications are discussed, along with next steps in exploring the role of coping in processes of resilience

Mid-Miocene cooling and the extinction of tundra in continental Antarctica

A major obstacle in understanding the evolution of Cenozoic climate has been the lack of well dated terrestrial evidence from high-latitude, glaciated regions. Here, we report the discovery of exceptionally well preserved fossils of lacustrine and terrestrial organisms from the McMurdo Dry Valleys sector of the Transantarctic Mountains for which we have established a precise radiometric chronology. The fossils, which include diatoms, palynomorphs, mosses, ostracodes, and insects, represent the last vestige of a tundra community that inhabited the mountains before stepped cooling that first brought a full polar climate to Antarctica. Paleoecological analyses, 40Ar/39Ar analyses of associated ash fall, and climate inferences from glaciological modeling together suggest that mean summer temperatures in the region cooled by at least 8°C between 14.07 ± 0.05 Ma and 13.85 ± 0.03 Ma. These results provide novel constraints for the timing and amplitude of middle-Miocene cooling in Antarctica and reveal the ecological legacy of this global climate transition

Ionizing Doses Calculations for Low Energy Electrons in Silicon and Aluminum

International audienceThe electron transport at low and very low energy (10 eV-2 keV) is investigated with a Monte Carlo (MC) code in silicon and aluminum. The elastic scattering with nuclei is described by Mott's model of partial waves, whereas the inelastic collisions with electrons are described by the complex dielectric function theory. Comparisons of MC simulations with electron emission yields (EEY) and energy loss spectra experimentally measured in ultrahigh vacuum on Ar-etched samples are given. The practical ranges and the ionizing dose calculations are presented down to 10 eV for electrons in silicon and aluminum. The simulation results show a correlation between the EEY and the ionizing doses. At low energy, while the electrons stay in the first ~10 nm from the surface due to the elastic scattering, the EEY increases and the ratio of the ionizing dose over the incident energy decreases. Above 200 eV, when the electrons go deeper into the solid due to the inelastic scattering, the EEY decreases and the ionizing dose ratio increases

Monte Carlo Simulation of 3D Surface Morphologies for Secondary Electron Emission Reduction

International audienceLow energy electrons of few tens of eV may cause Multipactor breakdowns in waveguides driven by the Secondary Electron Emission Yield (SEY) of the walls. This risk is lowered by using low emissive surfaces and this topic has been studied experimentally and with numerical simulations. The dependence of the SEY on surface properties is well known*. Surface morphology has been widely used to reduce the SEY by forming roughness patterns on the surface**. All patterns do not have the same efficiency so their analysis in terms of SEY is relevant. Monte-Carlo simulation codes can be used to study the processes behind the SEY. The MicroElec module of GEANT4 has recently been extended with more materials and processes and validated with experimental data for SEY calculations**. In this work, simulation results are shown for a bulk sample capped with different roughness patterns. The effects of the shape parameters on the SEY are studied for typical dimensions between 20 µm and 100 µm. The results are checked with experimental SEY measurements on samples with similar roughness patterns

Experimental Evidence of Large Dispersion of Deposited Energy in Thin Active Layer Devices

International audienceExperimental data are reported, showing that heavy-ion induced deposited energy dispersion increases with decreasing sensitive layer thickness. Geant4 simulations provide insight into the mechanisms involved. Implications for device testing and radiation hardness assurance are discussed

Simulation of Single Particle Displacement Damage in Silicon – Part II: Generation and Long-Time Relaxation of Damage Structure

International audienceA statistical study of displacement cascades induced by silicon Primary Knock-on Atoms (PKA) in bulk silicon is performed by running a large number of molecular dynamics (MD) simulations. The choice of the PKA species and energy varying from 1 to 100 keV comes from a previous particle-matter simulation [1]. The electronic stopping power missing in standard MD simulations is here taken into account using the Two Temperature Model (TTM). This prevents from overestimating the number of created defects. The damaged atomic structures obtained after one nanosecond of MD simulation are not representative of what is observed in image sensors for example after several minutes. For this reason, the kinetic Activation Relaxation Technique (k-ART) is used in a second step, allowing to access longer simulation times of up to second. The obtained damaged structures can then be compared with experimental observations. Analyses reveal two possible links between the simulated structures and the measurements in solid-state image sensors. First, the cluster size distribution exhibits a shape similar to the measured exponential distribution of Dark Current (DC). Second, the temporal evolution of metastable atomic configurations resembles experimental DC-Random-Telegraph-Signals

Impact of the radial ionization profile on SEE prediction for SOI transistors and SRAMs beyond the 32-nm technological node

International audienceThe relative contribution of the radial ionization profile on SEE prediction is investigated using MUSCA-SEP3 , in comparison with the classical approach considering the ion track as a series of punctual charges. The new approach is validated against experimental results, for three technology generations of PDSOI transistors and for two generations of SOI SRAM cells, showing better agreement than the punctual approach. The impact of the radial approach on the evaluation of SEU cross section as compared to the punctual approach is then investigated for nanometric SOI SRAM cells, beyond the 32-nm technological node. The influence of the radial dimension of the ion track is shown to increase with technology generation. The impact of the ion mass and energy on the ratio between radial and punctual SEU cross section is also investigated

Transient Radiation Responses of Optical Fibers: Influence of MCVD Process Parameters

International audienceA dedicated set of fibers elaborated via the Modified Chemical Vapor Deposition (MCVD) technique is used to study the influence of composition and drawing parameters on their responses to an X-ray pulse representative of the radiation environments associated with Megajoule class lasers. These canonical fibers were designed to highlight the impact of these parameters on the amplitude and kinetics of the transient pulsed X-ray Radiation Induced Attenuation (RIA) at room temperature. From preforms differing by their core composition, three optical fibers were elaborated by varying the tension and speed during the drawing process. No or only slight RIA change results from the tested variations in drawing process parameters of Ge-doped, F-doped, and pure-silica-core fibers. This study reveals that the drawing process is not the main parameter to be optimized in order to enhance the radiation tolerance of MCVD specialty optical fibers for the LMJ harsh environment. From the hardness assurance point of view, a specialty fiber sufficiently tolerant to this environment should be robust against changes in the drawing process. The origins of the RIA observed in the different fibers are discussed on the basis of spectral decomposition of their measured RIA spectra, using sets of defects from the literature and related to the different core dopants. This analysis highlights the limits of the well-known defect set to reproduce the RIA above 1 $mu{rm m}$ for Ge-doped fibers whereas self-trapped holes and chlorine-related species seem responsible for the transient responses of pure-silica-core and F-doped fibers

Charge Collection Analysis under Heavy Ion Irradiation in Multiple-Gate Devices: FinFETs and Nanowires

International audienceWe investigate Single-Event Transients (SET) in various designs of multiple-gate devices: FinFETs and nanowires. Heavy ion experimental results are explained by using a thorough charge collection analysis of fast transients measured on dedicated test structures. Multi-level simulations are performed to get new insights into the charge collection mechanisms in multiple-gate devices. Implications for multiple-gate device design hardening are finally discussed