The impact of screen time and green time on mental health in children and adolescents during the COVID-19 pandemic

The COVID-19 pandemic has affected the life of children and adolescents in an unpredecented way, limiting, among others, everyday activities with direct social contacts to mitigate the spread of the virus. These limitations have been associated with worse mental health. Yet, little is known about the underlying mechanisms. In the present study, we focused on two activities that have been likely affected by mitigation measures: screen time and green time. We investigated how screen time and green time influenced each during the pandemic, how they affected children’s and adolescents' mental health, and which role socio-demographic characteristics have in predicting screen time, green time, and mental health. We used data collected over between autumn 2020 and spring 2021 from 844 participants aged 5 to 19 of a population-based, prospective cohort study in Ticino, Switzerland. We analyzed the data using an extended version of the Random Intercept Cross-Lagged Panel Model with time-invariant socio-demographic covariates and mental health as outcome. Results showed that, at the between-person level, screen time was a risk factor and green time a protective factor of mental health. However, within-person deviations of screen time and green time during the pandemic did not consistently predict mental health. Furthermore, they did not influence each other over time. Gender, age, socio-economic background, Body Mass Index and the availability of green space nearby all influenced stable measures of green time and screen time (i.e., random intercepts). Our results highlight the need for targeted actions to promote green time and raise awareness about the detrimental effect of screen time on children’s and adolescents’ mental health.

Stability of Vocal Variables Measured During the Early Communication Indicator for Children With Autism Spectrum Disorder

The Early Communication Indicator (ECI) was designed to measure expressive communication progress in young children. We evaluated using the 6-min ECI procedure for a new purpose—a sampling context for stable measures of vocal development of young children with autism spectrum disorder (ASD). We evaluated how many ECI sessions were required to adequately stabilize estimates of volubility, communicative use, and phonological complexity of vocalizations at two periods (average of 10 months apart). Participants included 83 young children with ASD (M age = 23.33 months). At study initiation, two phonological complexity variables required two sessions; other variables required three. At study endpoint, all variables required fewer sessions. Findings support the feasibility and stability of using the ECI for the new purpose.

Strides to Achieve a Stable Symmetry Index During Running

Context: The quality of running mechanics is often characterized by limb pattern symmetry and used to support clinical decisions throughout the rehabilitation of lower-extremity injuries. It is valuable to ensure that gait analyses provide stable measures while not asking an individual to complete an excessive number of running strides. The present study aimed to determine the minimum number of strides required to establish a stable mean symmetry index (SMSI) of discrete-level measures of spatiotemporal parameters, joint kinematics, and joint kinetics. Further, the study aimed to determine if differences occurred between random and consecutive strides for directional and absolute symmetry indices. Design: Descriptive laboratory study. Methods: A sequential average was used to determine how many strides were required to achieve a SMSI within a 60-second trial. Multiple 2-factor repeated-measure analysis of variances were used to determine if differences between bins of strides and symmetry calculations were significantly different. Results: A median SMSI was achieved in 15 strides for all biomechanical variables. There were no significant differences (P > .05) found between consecutive and random bins of 15 strides within a 60-second trial. Although there were significant differences between symmetry calculation values for most variables (P < .05), there appeared to be no systematic difference between the numbers of strides required for stable symmetry for either index. Conclusions: As 15 strides were sufficient to achieve a SMSI during running, a continued emphasis should be placed on the number of strides collected when examining interlimb symmetry.

Temporal stability of fMRI in medetomidine-anesthetized rats

Medetomidine has become a popular choice for anesthetizing rats during long-lasting sessions of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI). Despite this, it has not yet been thoroughly established how commonly reported fMRI readouts evolve over several hours of medetomidine anesthesia and how they are affected by the precise timing, dose, and route of administration. We used four different protocols of medetomidine administration to anesthetize rats for up to six hours and repeatedly evaluated somatosensory stimulus-evoked BOLD responses and resting state functional connectivity. We found that the temporal evolution of fMRI readouts strongly depended on the method of administration. Intravenous administration of a medetomidine bolus (0.05 mg/kg), combined with a subsequent continuous infusion (0.1 mg/kg/h), led to temporally stable measures of stimulus-evoked activity and functional connectivity throughout the anesthesia. Deviating from the above protocol—by omitting the bolus, lowering the medetomidine dose, or using the subcutaneous route—compromised the stability of these measures in the initial two-hour period. We conclude that both an appropriate protocol of medetomidine administration and a suitable timing of fMRI experiments are crucial for obtaining consistent results. These factors should be considered for the design and interpretation of future rat fMRI studies.

Stochastic stability of invariant measures: The 2D Euler equation

In finite-dimensional dissipative dynamical systems, stochastic stability provides the selection of the physically relevant measures. That this might also apply to systems defined by partial differential equations, both dissipative and conservative, is the inspiration for this work. As an example, the 2D Euler equation is studied. Among other results this study suggests that the coherent structures observed in 2D hydrodynamics are associated with configurations that maximize stochastically stable measures uniquely determined by the boundary conditions in dynamical space.

Temporal stability of fMRI in medetomidine-anesthetized rats

Medetomidine has become a popular choice for anesthetizing rats during long-lasting sessions of blood-oxygen-level dependent (BOLD) functional magnetic resonance imaging (fMRI). Despite this, it has not yet been established how commonly reported fMRI readouts evolve over several hours of medetomidine anesthesia and how they are affected by the precise timing, dose, and route of administration. We used four different protocols of medetomidine administration to anesthetize rats for up to six hours and repeatedly evaluated somatosensory stimulus-evoked BOLD responses and resting state functional connectivity throughout. We found that the temporal evolution of fMRI readouts strongly depended on the method of administration. Protocols that combined an initial medetomidine bolus (0.05 mg/kg) together with a subsequent continuous infusion (0.1 mg/kg/h) led to temporally stable measures of stimulus-evoked activity and functional connectivity. However, when the bolus was omitted, or the dose of medetomidine lowered, the measures attenuated in a time-dependent manner. We conclude that medetomidine can sustain consistent fMRI readouts for up to six hours of anesthesia, but only with an appropriate administration protocol. This factor should be considered for the design and interpretation of future preclinical fMRI studies in rats.

LOCAL KEISLER MEASURES AND NIP FORMULAS

We study generically stable measures in the local, NIP context. We show that in this setting, a measure is generically stable if and only if it admits a natural finite approximation.