Look at Grandma! Joint visual attention over video chat during the COVID-19 pandemic.

Social interactions are crucial for many aspects of development. One developmentally important milestone is joint visual attention (JVA), or shared attention between child and adult on an object, person, or event. Adults support infants' development of JVA by structuring the input they receive, with the goal of infants learning to use JVA to communicate. When family members are separated from the infants in their lives, video chat sessions between children and distant relatives allow for shared back-and-forth turn taking interaction across the screen, but JVA is complicated by screen mediation. During video chat, when a participant is looking or pointing at the screen to something in the other person's environment, there is no line of sight that can be followed to their object of focus. Sensitive caregivers in the remote and local environment with the infant may be able to structure interactions to support infants in using JVA to communicate across screens. We observed naturalistic video chat interactions longitudinally from 50 triads (infant, co-viewing parent, remote grandmother). Longitudinal growth models showed that JVA rate changes with child age (4 to 20 months). Furthermore, grandmother sensitivity predicted JVA rate and infant attention. More complex sessions (sessions involving more people, those with a greater proportion of across-screen JVA, and those where infants initiated more of the JVA) resulted in lower amounts of JVA-per-minute, and evidence of family-level individual differences emerged in all models. We discuss the potential of video chat to enhance communication for separated families in the digital world.

Nucleation and Growth of GaAs on a Carbon Release Layer by Halide Vapor Phase Epitaxy.

We couple halide vapor phase epitaxy (HVPE) growth of III-V materials with liftoff from an ultrathin carbon release layer to address two significant cost components in III-V device - epitaxial growth and substrate reusability. We investigate nucleation and growth of GaAs layers by HVPE on a thin amorphous carbon layer that can be mechanically exfoliated, leaving the substrate available for reuse. We study nucleation as a function of carbon layer thickness and growth rate and find island-like nucleation. We then study various GaAs growth conditions, including V/III ratio, growth temperature, and growth rate in an effort to minimize film roughness. High growth rates and thicker films lead to drastically smoother surfaces with reduced threading dislocation density. Finally, we grow an initial photovoltaic device on a carbon release layer that has an efficiency of 7.2%. The findings of this work show that HVPE growth is compatible with a carbon release layer and presents a path toward lowering the cost of photovoltaics with high throughput growth and substrate reuse.

Presence at a distance: Video chat supports intergenerational sensitivity and positive infant affect during COVID-19.

COVID-19 disrupted infant contact with people beyond the immediate family. Because grandparents faced higher COVID-19 risks due to age, many used video chat instead of interacting with their infant grandchildren in person. We conducted a semi-naturalistic, longitudinal study with 48 families, each of whom submitted a series of video chats and surveys, and most (n = 40) also submitted a video of an in-person interaction. Families were mostly highly-educated, White/Caucasian, and lived between 1 and 2700 miles apart. We used multilevel models to examine grandparents' and parents' sensitivity during video chat across time (centered at February 1, 2021, the approximate date of vaccine availability). Grandparent video chat sensitivity changed as a function of date and parent sensitivity. Parent sensitivity changed as a function of date, grandparent sensitivity, and geographic distance. We then modeled infants' affective valence during video chat and in-person interactions with their grandparents, which was only predicted by grandparent sensitivity, not modality or other factors. This study demonstrates that caregivers were sensitive toward infants during video chat interactions despite fluctuations in family stress and reduced in-person contact during COVID-19 and that grandparent sensitivity predicted positive infant affect during both video chat and in-person interactions.

Look At That! Video Chat and Joint Visual Attention Development Among Babies and Toddlers.

Although many relatives use video chat to keep in touch with toddlers, key features of adult-toddler interaction like joint visual attention (JVA) may be compromised in this context. In this study, 25 families with a child between 6 and 24 months were observed using video chat at home with geographically separated grandparents. We define two types of screen-mediated JVA (across- and within-screen) and report age-related increases in the babies' across-screen JVA initiations, and that family JVA usage was positively related to babies' overall attention during video calls. Babies today are immersed in a digital world where formative relationships are often mediated by a screen. Implications for both infant social development and developmental research are discussed.