It is anticipated that the novel coronavirus disease 2019 (COVID‐19) pandemic and associated societal response will have wide‐ranging impacts on youth development and mental health. Sleep is crucial ...for child and adolescent health and well‐being, and the potential for sleep problems to emerge or worsen during and following the pandemic is high. This may be particularly true for children and adolescents who are at heightened risk for the onset of sleep and mental health disturbances and for those whom developmental changes impacting sleep are rapidly occurring. Youth with preexisting psychopathologies (including anxiety and depression) and neurodevelopmental conditions (including attention‐deficit/hyperactivity disorder and autism spectrum disorder) could be especially vulnerable to disturbed sleep during this period of change and uncertainty. It is thus imperative that sleep considerations be part of research and clinical initiatives aimed at understanding and mitigating the impact of the COVID‐19 pandemic in children and adolescents. This article considers ways in which the pandemic may impact sleep, including research and clinical implications.
Observation of a prethermal discrete time crystal Kyprianidis, A.; Machado, F.; Morong, W. ...
Science (American Association for the Advancement of Science),
06/2021, Volume:
372, Issue:
6547
Journal Article
Peer reviewed
Open access
Prethermal time crystal
Characterizing and understanding different phases of matter in equilibrium is usually associated with the process of thermalization, where the system equilibrates. Recent ...efforts probing nonequilibrium systems have revealed that periodic driving of the system can suppress the natural tendency for equilibration yet still form new, nonequilibrium phases. Kyprianidis
et al.
used a quantum simulator composed of 25 trapped ion qubits and spins to observe such a nonequilibrium phase of matter: the disorder-free prethermal discrete time crystal. The flexibility and tunability of their quantum simulator provide a powerful platform with which to study the exotic phases of matter.
Science
, abg8102, this issue p.
1192
An ion trap quantum simulator was used to observe signatures of a prethermal discrete time crystal.
Extending the framework of statistical physics to the nonequilibrium setting has led to the discovery of previously unidentified phases of matter, often catalyzed by periodic driving. However, preventing the runaway heating that is associated with driving a strongly interacting quantum system remains a challenge in the investigation of these newly discovered phases. In this work, we utilize a trapped-ion quantum simulator to observe the signatures of a nonequilibrium driven phase without disorder—the prethermal discrete time crystal. Here, the heating problem is circumvented not by disorder-induced many-body localization, but rather by high-frequency driving, which leads to an expansive time window where nonequilibrium phases can emerge. Floquet prethermalization is thus presented as a general strategy for creating, stabilizing, and studying intrinsically out-of-equilibrium phases of matter.
Summary Substantial research attention has been devoted to understanding the importance and impact of sleep in children and adolescents. Traditionally, this has focused on mean sleep variables (e.g., ...a child’s “typical” or average sleep duration), yet research increasingly suggests that intraindividual variability (IIV) of sleep/wake patterns (sometimes referred to as sleep variability or night-to-night variability) regularly occurs and may have implications for adjustment. A systematic search of five electronic databases identified 52 empirical studies published between 2000 and 2015 that examined correlates of sleep IIV in children and adolescents, with a recent increase in the publication rate of such studies. Identified studies were often atheoretical and included post hoc analyses, though IIV in select aspects of sleep does appear to be associated with increasing age/pubertal status, non-White race, physical and neurodevelopmental conditions (e.g., attention-deficit/hyperactivity disorder; autism), psychopathology symptoms (e.g., anxiety, depression, inattention), body weight, stress, aspects of cognitive functioning, and poorer sleep functioning/habits. The limited intervention work examining sleep IIV in adolescents is promising, though studies are needed using more rigorous intervention designs. Clinical sleep recommendations may not only need to address overall sleep duration and sleep habits but also the stability of sleep duration and timing. It will be important for future research examining sleep IIV in children and adolescents to use a developmental framework in advancing theory pertaining to the causes, mechanisms, moderators, and outcomes of sleep IIV in youth, and a conceptual model is proposed to help guide such efforts.
Background
The impact of chronic stressors like the COVID‐19 pandemic is likely to be magnified in adolescents with pre‐existing mental health risk, such as attention‐deficit/hyperactivity disorder ...(ADHD). This study examined changes in and predictors of adolescent mental health from before to during the COVID‐19 pandemic in the Southeastern and Midwestern United States.
Methods
Participants include 238 adolescents (132 males; ages 15–17; 118 with ADHD). Parents and adolescents provided ratings of mental health symptoms shortly before the COVID‐19 pandemic and in spring and summer 2020.
Results
Adolescents on average experienced an increase in depression, anxiety, sluggish cognitive tempo, inattentive, and oppositional/defiant symptoms from pre‐COVID‐19 to spring 2020; however, with the exception of inattention, these symptoms decreased from spring to summer 2020. Adolescents with ADHD were more likely than adolescents without ADHD to experience an increase in inattentive, hyperactive/impulsive, and oppositional/defiant symptoms. Adolescents with poorer pre‐COVID‐19 emotion regulation abilities were at‐risk for experiencing increases in all mental health symptoms relative to adolescents with better pre‐COVID‐19 emotion regulation abilities. Interactive risk based on ADHD status and pre‐COVID‐19 emotion regulation abilities was found for inattention and hyperactivity/impulsivity, such that adolescents with ADHD and poor pre‐COVID‐19 emotion regulation displayed the highest symptomatology across timepoints. Lower family income related to increases in inattention but higher family income related to increases in oppositional/defiant symptoms.
Conclusions
The early observed increases in adolescent mental health symptoms during the COVID‐19 pandemic do not on average appear to be sustained following the lift of stay‐at‐home orders, though studies evaluating mental health across longer periods of time are needed. Emotion dysregulation and ADHD increase risk for sustained negative mental health functioning and highlight the need for interventions for these populations during chronic stressors. Results and clinical implications should be considered within the context of our predominately White, middle class sample.
A quantum simulator is a type of quantum computer that controls the interactions between quantum bits (or qubits) in a way that can be mapped to certain quantum many-body problems. As it becomes ...possible to exert more control over larger numbers of qubits, such simulators will be able to tackle a wider range of problems, such as materials design and molecular modelling, with the ultimate limit being a universal quantum computer that can solve general classes of hard problems. Here we use a quantum simulator composed of up to 53 qubits to study non-equilibrium dynamics in the transverse-field Ising model with long-range interactions. We observe a dynamical phase transition after a sudden change of the Hamiltonian, in a regime in which conventional statistical mechanics does not apply. The qubits are represented by the spins of trapped ions, which can be prepared in various initial pure states. We apply a global long-range Ising interaction with controllable strength and range, and measure each individual qubit with an efficiency of nearly 99 per cent. Such high efficiency means that arbitrary many-body correlations between qubits can be measured in a single shot, enabling the dynamical phase transition to be probed directly and revealing computationally intractable features that rely on the long-range interactions and high connectivity between qubits.
Spontaneous symmetry breaking is a fundamental concept in many areas of physics, including cosmology, particle physics and condensed matter. An example is the breaking of spatial translational ...symmetry, which underlies the formation of crystals and the phase transition from liquid to solid. Using the analogy of crystals in space, the breaking of translational symmetry in time and the emergence of a 'time crystal' was recently proposed, but was later shown to be forbidden in thermal equilibrium. However, non-equilibrium Floquet systems, which are subject to a periodic drive, can exhibit persistent time correlations at an emergent subharmonic frequency. This new phase of matter has been dubbed a 'discrete time crystal'. Here we present the experimental observation of a discrete time crystal, in an interacting spin chain of trapped atomic ions. We apply a periodic Hamiltonian to the system under many-body localization conditions, and observe a subharmonic temporal response that is robust to external perturbations. The observation of such a time crystal opens the door to the study of systems with long-range spatio-temporal correlations and novel phases of matter that emerge under intrinsically non-equilibrium conditions.
Several studies have questioned the stability of attention-deficit hyperactivity disorder (ADHD) from childhood to adulthood. This systematic review illustrates how variability in diagnostic methods ...influences adult ADHD persistence estimates. Systematic database searches identified studies reporting adult ADHD persistence rates that were published in English between Jan 1, 1992, and May 31, 2016. Study inclusion criteria were systematic childhood diagnosis of attention-deficit disorder, ADHD, or a research diagnostic protocol that matched DSM-III, DSM-III-R, or DSM-IV standards; mean childhood age of younger than 12·0 years with no participants older than 18·0 years; and mean adult age of 18·0 years or older with no participants younger than 17·0 years. Across 12 included samples, we identified 41 estimates of ADHD persistence, which ranged from 4·0% to 77·0%. Methods of diagnosing ADHD in adulthood varied widely with respect to source of information, diagnostic instruments (eg, rating scales, interviews), diagnostic symptom threshold, and whether impairment was required for diagnosis. Sole reliance on self reports and a strict threshold of six DSM symptoms led to very low persistence estimates. To minimise false-negative and false-positive classifications, recommended methods for determining adult persistence of ADHD include collecting self and informant ratings, requiring the presence of impairment, and using an age-appropriate symptom threshold. Very few persistence estimates utilised these methods, but those that did indicated persistence rates of 40-50%.
This study focuses on drivers for changing urban flood risk. We suggest a framework for guiding climate change adaptation action concerning flood risk and manageability in cities. The identified key ...drivers of changing flood hazard and vulnerability are used to provide an overview of each driver's impact on flood risk and manageability at the city level. We find that identified drivers for urban flood risk can be grouped in three different priority areas with different time horizon. The first group has high impact but is manageable at city level. Typical drivers in this group are related to the physical environment such as decreasing permeability and unresponsive engineering. The second group of drivers is represented by public awareness and individual willingness to participate and urbanization and urban sprawl. These drivers may be important and are manageable for the cities and they involve both short-term and long-term measures. The third group of drivers is related to policy and long-term changes. This group is represented by economic growth and increasing values at risk, climate change, and increasing complexity of society. They have all high impact but low manageability. Managing these drivers needs to be done in a longer time perspective, e.g., by developing long-term policies and exchange of ideas.
•Decreasing permeability and unresponsive engineering mean high urban flood risk.•Public awareness and urban sprawl have moderate impact on flood risk.•Increasing values at risk and complexity of society also affect urban flood risk.•Methods can be combined with a mixed expert and stakeholder participatory approach.
The maintenance of synaptic changes resulting from long-term potentiation (LTP) is essential for brain function such as memory and learning. Different LTP phases have been associated with diverse ...molecular processes and pathways, and the molecular underpinnings of LTP on the short, as well as long time scales, are well established. However, the principles on the intermediate time scale of 1-6 hours that mediate the early phase of LTP (E-LTP) remain elusive. We hypothesize that the interplay between specific features of postsynaptic receptor trafficking is responsible for sustaining synaptic changes during this LTP phase. We test this hypothesis by formalizing a biophysical model that integrates several experimentally-motivated mechanisms. The model captures a wide range of experimental findings and predicts that synaptic changes are preserved for hours when the receptor dynamics are shaped by the interplay of structural changes of the spine in conjunction with increased trafficking from recycling endosomes and the cooperative binding of receptors. Furthermore, our model provides several predictions to verify our findings experimentally.
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