COVID-19 first lockdown as a window into language acquisition: Associations between caregiver-child activities and vocabulary gains

The COVID-19 pandemic, and the resulting closure of daycare centers worldwide, led to unprecedented changes in children’s learning environments. This period of increased time at home with caregivers, with limited access to external sources (e.g., daycares) provides a unique opportunity to examine the associations between the caregiver-child activities and children’s language development. The vocabularies of 1742 children aged8-36 months across 13 countries and 12 languages were evaluated at the beginning and end of the first lockdown period in their respective countries(from March to September 2020). Children who had less passive screen exposure and whose caregivers read more to them showed larger gains in vocabulary development during lockdown, after controlling for SES and other caregiver-child activities. Children also gained more words than expected (based on normative data) during lockdown; either caregivers were more aware of their child’s development or vocabulary development benefited from intense caregiver-child interaction during lockdown

"Call us by our name": Quality of care and wellbeing from the perspective of girls in residential care facilities who are commercially and sexually exploited by "loverboys"

In the Netherlands, thirteen organizations offer specialized care services for commercially and sexually exploited (CSE) girls who are underage. Quality and effectiveness of these services have only sparsely been evaluated, while existing quantitative measures of treatment success mainly include the perspective of professionals. As a result, minimal insight exists as to whether current practices are sufficiently tailored to the needs of CSE girls. We carried out an ethnographic Participatory Health Research project with the objective to gain insight in CSE girls’ care experiences needs, and understand what they think contributes to good care. We worked with 27 girls from three residential youth facilities using a range of creative methods. Girls discussed their need for privacy and self-determination in a highly surveilled environment that aims to shield them from exploitative relationships with boys and men. Protective rules and measures impact their ability to build trusting, reciprocal relationships with group leaders, as well as their opportunities to make mistakes and learn without consequences. Girls wanted care that centered on their individual needs, and did not see their victimization as defining those needs. They called for group leaders to be responsive to their sometimes conflicting values by providing both a protective and autonomous space for care delivery. Navigating this complexity is a balancing act for professionals caring for CSE girls. The perspectives reported in this paper will be integrated in the measurement protocol of a broader N = 1 effectiveness study

Atomistic simulations of graphite etching at realistic time scales

Hydrogen-graphite interactions are relevant to a wide variety of applications, ranging from astrophysics to fusion devices and nano-electronics. In order to shed light on these interactions, atomistic simulation by Molecular Dynamics (MD) has been shown to be an invaluable tool. It suffers, however, from severe time-scale limitations. In this work we employ the recently developed Collective Variable-Driven Hyperdynamics (CVHD) method to hydrogen etching of graphite for varying inter-impact times up to a realistic value of 1 ms, which corresponds to a flux of ~1020 m-2s-1. The results show that the erosion yield, hydrogen surface coverage and species distribution are significantly affected by the time between impacts. This can be explained by the higher probability for C-C bond breaking due to the prolonged exposure to thermal stress and the subsequent transition from ion- to thermal-induced etching. This latter regime of thermal-induced etching - chemical erosion - is here accessed for the first time using atomistic simulations. In conclusion, this study demonstrates that accounting for long time-scales significantly affects ion bombardment simulations and should not be neglected in a wide range of conditions, in contrast to what is typically assumed

From nanometre to millimetre: a range of capabilities for plasma-enabled surface functionalization and nanostructuring

Driven by the innate tendency of the system to attain a local energy minimum, self-organization enables the creation of complex systems out of relatively simple parts and elements. The ability to form hierarchical, multicomponent systems that may be difficult, or even impossible, to fabricate using pre-set, template-enabled processes makes self-organisation very attractive for the synthesis and assembly of advanced material systems across multiple length scales. Yet, driving and controlling such self-organisation processes is not a trivial task as they often arise from a complex interplay of physical and chemical processes. These in turn depend on the environment in which self-organisation takes place. In this topical review, we focus on one such environment and outline unique opportunities, salient characteristics and challenges presented by self-organization on surfaces exposed to partially ionised gases, i.e. plasmas. Using a select number of recent examples, we aim to show how salient features of plasma environments, particularly high fluxes of energy and matter from the plasma to the surface, enable functionalization and growth of complex nanostructures and metamaterials via self-organization on plasma-exposed surfaces. We will show how by controlling different physical and chemical parameters of the plasma environment and how it interacts with surfaces, it is possible to control self-organization processes at multiple length scales, making it a promising enabling platform for nanosynthesis. We will discuss examples starting from the self-driven growth of perfect crystalline lattices, such as nano-diamonds and graphenes at the nanoscale, all the way to template- and pattern-free synthesis of large, highly ordered arrays of nanostructures at millimetre and even centimetre scales. We will outline the key enabling features of plasmas that drive these processes at respective scales, focusing predominantly on plasma-induced electric fields at the surface or in the plasma-nanostructure sheath, as well as charge-related effects. The outlook section summarizes advantages of plasma-driven self-organization, and outlines principal challenges and opportunities for the development of this field

Dust formation from arc spots on nanostructured tungsten surface

Arcing experiments were conducted in the linear plasma device Pilot-PSI, where a pulsed plasma was superimposed to a steady state plasma. The arcing was observed by a fast framing camera, and the sample was analyzed with a transmission electron microscope. Observations of glowing objects released from the sample in response to the arcing and destruction of the fuzzy layer at the edge of the arc trail without significant melting suggested that dust was formed and released from the surface in response to arcing

Single-crystal and polycrystalline diamond erosion studies in Pilot-PSI

Diamond is a promising candidate for enhancing the negative-ion surface production in the ion sources for neutral injection in fusion reactors; hence evaluation of its reactivity towards hydrogen plasma is of high importance. Single crystal and polycrystalline diamond samples were exposed in Pilot-PSI with the D+ flux of (4‒7)·1024 m−2s−1 and the impact energy of 7–9 eV per deuteron at different surface temperatures; under such conditions physical sputtering is negligible, however chemical sputtering is important. Net chemical sputtering yield Y = 9.7·10−3 at/ion at 800 °C was precisely measured ex-situ using a protective platinum mask (5 × 10 × 2 μm) deposited beforehand on a single crystal followed by the post-mortem analysis using Transmission Electron Microscopy (TEM). The structural properties of the exposed diamond surface were analyzed by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Gross chemical sputtering yields were determined in-situ by means of optical emission spectroscopy of the molecular CH A-X band for several surface temperatures. A bell-shaped dependence of the erosion yield versus temperature between 400 °C and 1200 °C was observed, with a maximum yield of ∼1.5·10−2 at/ion attained at 900 °C. The yields obtained for diamond are relatively high (0.5–1.5)·10−2 at/ion, comparable with those of graphite. XPS analysis shows amorphization of diamond surface within 1 nm depth, in a good agreement with molecular dynamics (MD) simulation. MD was also applied to study the hydrogen impact energy threshold for erosion of [100] diamond surface at different temperatures

Dust formation from arc spots on nanostructured tungsten surface

Arcing experiments were conducted in the linear plasma device Pilot-PSI, where a pulsed plasma was superimposed to a steady state plasma. The arcing was observed by a fast framing camera, and the sample was analyzed with a transmission electron microscope. Observations of glowing objects released from the sample in response to the arcing and destruction of the fuzzy layer at the edge of the arc trail without significant melting suggested that dust was formed and released from the surface in response to arcing

Single-crystal and polycrystalline diamond erosion studies in Pilot-PSI

International audienceDiamond is a promising candidate for enhancing the negative-ion surface production in the ion sources for neutral injection in fusion reactors; hence evaluation of its reactivity towards hydrogen plasma is of high importance. High quality PECVD single crystal and polycrystalline diamond samples were exposed in Pilot-PSI with the D + flux of (4-7)·10 24 m-2 s-1 and the impact energy of 7-9 eV per deuteron at different surface temperatures; under such conditions physical sputtering is negligible, however chemical sputtering is important. Net chemical sputtering yield Y = 9.7·10-3 at/ion at 800°C was precisely measured ex-situ using a protective platinum mask (5x10x2 µm) deposited beforehand on a single crystal followed by the post-mortem analysis using Transmission Electron Microscopy (TEM). The structural properties of the exposed diamond surface were analyzed by Raman spectroscopy and X-ray Photoelectron Spectroscopy (XPS). Gross chemical sputtering yields were determined in-situ by means of optical emission spectroscopy of the molecular CH AX band for several surface temperatures. We observed a bell shape dependence of the erosion yield versus temperature between 400°C and 1200°C, with a maximum yield of ~1.5·10-2 at/ion attained at 900°C. The yields obtained for diamond are relatively high (0.51.5)·10-2 at/ion, comparable with those of graphite. XPS analyses show amorphization of diamond surface within 1 nm depth, in good agreement with molecular dynamics (MD) simulation. MD was also applied to study the hydrogen impact energy threshold for erosion of [100] diamond surface at different temperatures

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