How divergent are children's divergent movements? The role of cognition and expertise in a class-randomized cross-over trial.

This study aimed at investigating (1) the cognitive and motor predictors of divergent movement ability (DMA) in childhood and (2) the role of sport and enriched physical education (PE) experience. Participants were 165 fifth graders, aged 10-11 years, with different histories (onset and duration) of participation in enriched PE. They were assessed in cognitive/attentional and motor/sport skills and active play/sport habits at baseline, and six months later in DMA. Results of regression analyses showed an overall prediction of DMA by sport practice and a nuanced prediction of individual DMA indices (fluency, flexibility, originality) by decision making and spatial attention ability. Linear mixed models revealed better DMA in children exposed to enriched PE, with differential effects on DMA indices depending on its duration and earlier/later onset. The results identify novel cognitive determinants of children's DMA and suggest that sport practice and experience of designed enrichment in PE may benefit DMA.

Acute exercise and children's cognitive functioning: What is the optimal dose of cognitive challenge?

Acute bouts of exercise have the potential to benefit children's cognition. Inconsistent evidence on the role of qualitative exercise task characteristics calls for further investigation of the cognitive challenge level in exercise. Thus, the study aim was to investigate which "dose" of cognitive challenge in acute exercise benefits children's cognition, also exploring the moderating role of individual characteristics. In a within-subject experimental design, 103 children (Mage = 11.1, SD = 0.9, 48% female) participated weekly in one of three 15-min exergames followed by an Attention Network task. Exergame sessions were designed to keep physical intensity constant (65% HRmax) and to have different cognitive challenge levels (low, mid, high; adapted to the ongoing individual performance). ANOVAs performed on variables that reflect the individual functioning of attention networks revealed a significant effect of cognitive challenge on executive control efficiency (reaction time performances; p = .014, ƞ2p = .08), with better performances after the high-challenge condition compared to lower ones (ps < .015), whereas alerting and orienting were unaffected by cognitive challenge (ps > .05). ANOVAs performed on variables that reflect the interactive functioning of attention networks revealed that biological sex moderated cognitive challenge effects. For males only, the cognitive challenge level influenced the interactive functioning of executive control and orienting networks (p = .004; ƞ2p = .07). Results suggest that an individualized and adaptive cognitively high-challenging bout of exercise is more beneficial to children's executive control than less challenging ones. For males, the cognitive challenge in an acute bout seems beneficial to maintain executive control efficiency also when spatial attention resources cannot be validly allocated in advance. Results are interpreted referring to the cognitive stimulation hypothesis and arousal theory.

Leave the screen: The influence of everyday behaviors on self-reported interoception.

The influence of physical activity on interoception is apparent, however little is known about within-person variability following physical activity and sedentary behavior in daily life. To test this, 70 healthy adults (Mage 21.67 ± 2.50) wore thigh-mounted accelerometers for 7-days, with self-reported interoception recorded on movement-triggered smartphones. Participants additionally reported the predominant activity type performed across the last 15 min. Investigating this timeframe, multi-level analyses revealed that each one-unit increase in physical activity was associated with an increase in self-reported interoception (B = 0.0025, p = .013), whereas contrastingly, each one-minute increase in sedentary behavior was associated with a decrease (B = -0.06. p = .009). Investigating the influence of different activity types in comparison to screen time behavior, both partaking in exercise (B = 4.48, p < .001) and daily-life physical activity (B = 1.21, p < .001) were associated with an increase in self-reported interoception. Regarding other behavior categories, non-screen time behavior both with (B = 1.13, p < .001) and without (B = 0.67, p = .004) social interaction were also associated with an increase in self-reported interoception compared to screen-time behavior. Extending from previous laboratory-based studies, these findings indicate that physical activity influences interoceptive processes in real-life, further supplemented by the novel and contrasting findings regarding sedentary behavior. Furthermore, associations with activity type reveal important mechanistic information, highlighting the importance of reducing screen-time behavior to preserve and support interoceptive perceptions. Findings can be used to inform health recommendations for reducing screen-time behavior and guiding evidence-based physical activity interventions to promote interoceptive processes.

How is Cerebral Perfusion Associated with Functional Outcome in Pediatric Cancer Survivors?

Pediatric cancer survivors (PCS) experience functional difficulties and brain alterations. However, little is known about cerebral perfusion and its relationship to functional outcome (cognitive and motor performance) in PCS. We examined cerebral blood flow (CBF) in non-brain tumor PCS and the associations between CBF and age, as well as functional outcome. Forty PCS and 40 age-comparable controls were included. CBF did not differ between PCS and controls. CBF decreased with age only in controls. In PCS, CBF was associated with functional outcome. Our data indicate an altered relationship between age and CBF in survivors, with stronger brain-behavior mechanisms after cancer.

Dose-response relation between the duration of a cognitively challenging bout of physical exercise and children's cognition.

Acute bouts of physical exercise have the potential to benefit children's cognition. Inconsistent evidence calls for systematic investigations of dose-response relations between quantitative (intensity and duration) and qualitative (modality) exercise characteristics. Thus, in this study the optimal duration of an acute cognitively challenging physical exercise to benefit children's cognition was investigated, also exploring the moderating role of individual characteristics. In a within-subject experimental design, 104 children (Mage = 11.5, SD = 0.8, 51% female) participated weekly in one of four exergaming conditions of different durations (5, 10, 15, 20 min) followed by an Attention Network task (ANT-R). Exergame sessions were designed to keep physical intensity constant (65% HRmax ) and to have a high cognitive challenge level (adapted to the individual ongoing performance). Repeated measures ANOVAs revealed a significant effect of exercise duration on reaction times (RTs; p = 0.009, ƞ2 p = 0.11), but not on response accuracy. Post hoc analyses showed faster information processing speed after 15 min of exercise compared to 10 min (p = 0.019, ƞ2 p = 0.09). Executive control, alerting and orienting performances and interactions were unaffected by exercise duration (ps > 0.05). Among individual characteristics, habitual physical activity moderated duration effects on RTs. For more active children, exercise duration influenced the interaction between executive control and orienting (p = 0.034; ƞ2 p = 0.17) with best performances after the 15 min duration. Results suggest that an acute 15 min cognitively high-challenging bout of physical exercise enhances allocable resources, which in turn facilitate information processing, and-for more active children only-also executive processes. Results are interpreted according to the arousal theory and cognitive stimulation hypothesis.

COVID-19: Sports activity and health-related quality of life of Swiss children and adolescents before and during the initial stay at home period.

The aim of this study was to investigate sports activity and health-related quality of life (HRQoL) of Swiss children and adolescents (7-16 years) during the national COVID-19 stay at home (SaH) period. In total, 237 parent-child pairs gave information about HRQoL and sports activity (duration and type) before and during SaH. Results show that sports activity decreased during SaH and was also positively related to HRQoL. These findings indicate that sports activity of children and adolescents should be promoted during SaH, for which innovative home-based interventions may be useful.

Personal and Social Resources Are Linked to Cognition and Health-Related Quality of Life in Childhood Cancer Survivors.

Personal and social resources may buffer the adverse effects of childhood cancer and its impact on cognition and quality of life. While childhood cancer survivors show domain-specific cognitive difficulties, little is known about their personal and social resources. We therefore investigated personal and social resources and their association with cognitive and quality-of-life outcomes in childhood cancer survivors. Seventy-eight survivors of childhood cancer of different etiologies (aged 7−16 years; ≥one year since treatment) and fifty-six healthy controls were included. Cognitive outcome was assessed by neuropsychological tests; personal and social resources, as well as health-related quality of life, were assessed by standardized questionnaires. In the social resource domain, peer integration was worse in survivors than in controls (puncorr < 0.04, d = 0.33). Personal resources and all other subscales of social resources did not significantly differ between survivors and controls. In survivors, the global resource score was significantly correlated with processing speed (r = 0.39, pcorr < 0.001) and quality of life (parent: r = 0.44; self-report: r = 0.46; pscorr < 0.001). In controls, no association occurred between resources and cognitive outcome, and the correlation between the global resource score and quality of life did not withstand correction for multiple comparison (parent: r = 0.28; self-report: r = 0.40, psuncorr < 0.001). After an adverse event such as childhood cancer, resources might play a particularly buffering role on cognitive performance and quality of life (when compared to the everyday life of healthy controls). This highlights the importance of interventions that strengthen the resources of children and their families, even years after cancer. Such resource-focused intervention could help to counteract long-term sequelae in cognitive outcomes and health-related quality of life.

Effects of Classroom-Based Resistance Training With and Without Cognitive Training on Adolescents' Cognitive Function, On-task Behavior, and Muscular Fitness.

Aim: Participation in classroom physical activity breaks may improve children's cognition, but few studies have involved adolescents. The primary aim of this study was to examine the effects of classroom-based resistance training with and without cognitive training on adolescents' cognitive function. Methods: Participants were 97 secondary school students (45.4% females, mean age 15.78 ± 0.44). Four-year 10 classes from one school were included in this four-arm cluster randomized controlled trial. Classes were randomly assigned to the following groups: sedentary control with no cognitive training, sedentary with cognitive training, resistance training without cognitive training, and resistance training with cognitive training. Sessions varied in levels of both cognitive demand and resistance training (i.e., high vs. low) and were administered three times per week for 4 weeks (12 sessions). Inhibition, cognitive flexibility, episodic memory, on-task behavior, and muscular fitness were assessed at baseline and post-test. Linear mixed models were used to examine changes within and between groups. Results: In comparison with the control group, episodic memory improved significantly in the resistance training without cognitive training group (-9.87 units, 95% CI: -17.71 to -2.03, p = 0.014, d = 0.72). There were no group-by-time effects for inhibition or cognitive flexibility. Classroom activity breaks both with and without cognitive demand improved participants' on-task behavior in comparison with the control and sedentary group. The resistance training programs did not lead to improvements in muscular fitness. Conclusion: Participation in body weight resistance training without cognitive training led to selective improvements in episodic memory. No training effects were found for inhibition or cognitive flexibility. A longer study period may be necessary to induce improvements in muscular fitness and associated changes in inhibition and cognitive flexibility. Clinical Trial Registration: https://www.anzctr.org.au/ACTRN12621001341819.aspx, Australian New Zealand Clinical Trials Registry-ACTRN12621001341819.

COVID-19: Physical Activity and Quality of Life in a Sample of Swiss School Children during and after the First Stay-at-Home.

COVID-19 restrictions and the instructions to stay at home (SaH) may have had an impact on child behavior including physical activity (PA) and health-related quality of life (HRQoL) in Switzerland. Therefore, we investigated PA and HRQoL during and after the SaH in 57 Swiss school children aged 7 to 12 years (M = 10.44; SD = 1.34). PA was measured using accelerometry (Actigraph GT3X) and HRQoL using the Kid-KINDLR questionnaire. During and post data was compared using paired sample t-tests. Independent t-tests were used to compare the HRQoL of physically active children with non-physically active children. PA in light (d = -0.56), moderate (d = -0.44), moderate-to-vigorous (d = -0.28) as well as overall HRQoL (d = -0.66), psychological well-being (d = -0.48), self-esteem (d = -0.39), friends (d = -0.70) and everyday functioning (d = -0.44), were significantly lower during SaH than afterwards. Children who adhered to PA recommendations (+60 min of moderate-to-vigorous PA) during SaH had a better overall HRQoL (d = 0.61) and psychological well-being (d = 0.56) than those who did not. Since PA levels and HRQoL were lower during SaH compared to afterwards, it seems that the restrictions negatively impacted children's PA and HRQoL. During future SaHs, promoting children's PA and HRQoL seems important.

Cognition, psychosocial functioning, and health-related quality of life among childhood cancer survivors.

Long-term sequelae of cancer and its treatment render childhood cancer (CC) survivors vulnerable to cognitive and behavioural difficulties and likely affect their quality of life (QoL). Our aim was to compare levels of cognition, psychosocial functioning, and health-related QoL of CC survivors to healthy controls and examine the associations between these three domains. Seventy-eight CC survivors (age range = 7-16 years, ≥ one year since cancer treatment) and 56 healthy controls were included. Cognition (i.e., fluid intelligence, executive functions, memory, processing speed, and selective attention), psychosocial functioning, and health-related QoL were assessed using standardized tests and questionnaires. The cognitive performance, parent-reported psychosocial behaviour, and health-related QoL of the CC survivors were within the normative range. However, working memory was significantly poorer in survivors than controls, and visuospatial working memory below the normative range was more commonly observed among survivors than among controls. Processing speed significantly predicted survivors' performance in executive functions. Among survivors, greater peer problems were significantly associated with poorer cognitive functions and health-related QoL. Despite the evidence for good intellectual functioning, which might point towards adequate reserves, in some survivors, domain-specific difficulties may emerge years after cancer relating to psychosocial development and QoL.

Staying Active under Restrictions: Changes in Type of Physical Exercise during the Initial COVID-19 Lockdown.

The COVID-19 pandemic and the associated governmental restrictions suddenly changed everyday life and potentially affected exercise behavior. The aim of this study was to explore whether individuals changed their preference for certain types of physical exercise during the pandemic and to identify risk factors for inactivity. An international online survey with 13,881 adult participants from 18 countries/regions was conducted during the initial COVID-19 related lockdown (between April and May 2020). Data on types of exercise performed during and before the initial COVID-19 lockdown were collected, translated, and categorized (free-text input). Sankey charts were used to investigate these changes, and a mixed-effects logistic regression model was used to analyze risks for inactivity. Many participants managed to continue exercising but switched from playing games (e.g., football, tennis) to running, for example. In our sample, the most popular exercise types during the initial COVID-19 lockdown included endurance, muscular strength, and multimodal exercise. Regarding risk factors, higher education, living in rural areas, and physical activity before the COVID-19 lockdown reduced the risk for inactivity during the lockdown. In this relatively active multinational sample of adults, most participants were able to continue their preferred type of exercise despite restrictions, or changed to endurance type activities. Very few became physically inactive. It seems people can adapt quickly and that the constraints imposed by social distancing may even turn into an opportunity to start exercising for some. These findings may be helpful to identify individuals at risk and optimize interventions following a major context change that can disrupt the exercise routine.

The Working Memory Network and Its Association with Working Memory Performance in Survivors of non-CNS Childhood Cancer.

Childhood cancer and its treatment puts survivors at risk of low working memory capacity. Working memory represents a core cognitive function, which is crucial in daily life and academic tasks. The aim of this functional MRI (fMRI) study was to examine the working memory network of survivors of childhood cancer without central nervous system (CNS) involvement and its relation to cognitive performance. Thirty survivors (aged 7-16 years, ≥ 1 year after cancer treatment) and 30 healthy controls performed a visuospatial working memory task during MRI, including a low- and a high-demand condition. Working memory performance was assessed using standardized tests outside the scanner. When cognitive demands increased, survivors performed worse than controls and showed evidence for slightly atypical working memory-related activation. The survivor group exhibited hyperactivation in the right-hemispheric superior parietal lobe (SPL) in the high- compared to the low-demand working memory condition, while maintaining their performance levels. Hyperactivation in the right SPL coincided with poorer working memory performance outside the scanner in survivors. Even in survivors of childhood cancer without CNS involvement, we find neural markers pointing toward late effects in the cerebral working memory network.AbbreviationsfMRI: Functional magnetic resonance imaging; CNS: Central nervous system; MNI: Montreal Neurological Institute; SES: Socioeconomic status; SPL: Superior parietal lobe.

Cortical Morphometry and Its Relationship with Cognitive Functions in Children after non-CNS Cancer.

Background: Childhood cancer survivors (Ccs) are at risk for cognitive late-effects, which might result from cortical alterations, even if cancer does not affect the brain. The study aimed to examine gray and white matter volume and its relationship to cognition. Methods: Forty-three Ccs of non-central nervous system cancers and 43 healthy controls, aged 7-16 years, were examined. Cognitive functions and fine motor coordination were assessed and T1-weighted images were collected for voxel-based morphometry. Results: Executive functions (p = .024, d = .31) were poorer in Ccs than controls, however still within the normal range. The volume of the amygdala (p = .011, ŋ2 = .117) and the striatum (p = .03, ŋ2 = .102) was reduced in Ccs. No significant structure-function correlations were found, neither in patients nor controls. Conclusion: Non-CNS childhood cancer and its treatment impacts on brain structures relevant to emotion processing.

Motor ability, physical self-concept and health-related quality of life in pediatric cancer survivors.

BACKGROUND: Cancer survivorship is frequently associated with severe late effects. However, research into pediatric cancer survivors on late effects in motor ability, physical self-concept and their relationship to quality of life is limited. METHODS: Using multiple regression analyses, 78 pediatric cancer survivors and 56 typically developing children were compared in motor ability, physical self-concept and health-related quality of life. In addition, mediational multi-group analyses between motor ability (independent variable), physical self-concept (mediator) and quality of life (dependent variable) were calculated. RESULTS: Pediatric cancer survivors had a lower motor ability (gHedges  = 0.863), a lower physical self-concept with regard to several scales of the PSDQ-S (gHedges  = 0.318-0.764) and a higher relative risk for a below average quality of life than controls (RR = 1.44). Children with a history of cancer involving the central nervous system showed poorer motor ability compared to those without central nervous system involvement (gHedges  = 0.591). Furthermore, the physical self-concept significantly mediated the relationship between motor ability and quality of life in pediatric cancer survivors but not in typically developing children. CONCLUSIONS: Results show the importance of monitoring and supporting the development of motor ability in the aftercare of pediatric cancer survivors. Physical activity interventions may be advisable to prevent physical activity-related late effects and potentially improve related psychosocial variables such as quality of life.

Impact of non-CNS childhood cancer on resting-state connectivity and its association with cognition.

INTRODUCTION: Non-central nervous system cancer in childhood (non-CNS CC) and its treatments pose a major threat to brain development, with implications for functional networks. Structural and functional alterations might underlie the cognitive late-effects identified in survivors of non-CNS CC. The present study evaluated resting-state functional networks and their associations with cognition in a mixed sample of non-CNS CC survivors (i.e., leukemia, lymphoma, and other non-CNS solid tumors). METHODS: Forty-three patients (off-therapy for at least 1 year and aged 7-16 years) were compared with 43 healthy controls matched for age and sex. High-resolution T1-weighted structural magnetic resonance and resting-state functional magnetic resonance imaging were acquired. Executive functions, attention, processing speed, and memory were assessed outside the scanner. RESULTS: Cognitive performance was within the normal range for both groups; however, patients after CNS-directed therapy showed lower executive functions than controls. Seed-based connectivity analyses revealed that patients exhibited stronger functional connectivity between fronto- and temporo-parietal pathways and weaker connectivity between parietal-cerebellar and temporal-occipital pathways in the right hemisphere than controls. Functional hyperconnectivity was related to weaker memory performance in the patients' group. CONCLUSION: These data suggest that even in the absence of brain tumors, non-CNS CC and its treatment can lead to persistent cerebral alterations in resting-state network connectivity.

Effects of Cognitive Training and Exergaming in Pediatric Cancer Survivors-A Randomized Clinical Trial.

PURPOSE: Although most pediatric cancer patients survive, those who undergo anticancer treatments like chemotherapy and/or radiotherapy are at a high risk for late effects, such as cognitive deficits. To counteract these deficits, feasible and effective interventions are needed. The aim of this study was to compare the effects of working memory training, exergaming, and a wait-list control condition on cognitive functions in pediatric cancer survivors. METHODS: In a parallel-group randomized trial, 69 pediatric cancer survivors aged 7-16 yr (mean = 11.35, SD = 3.53) were randomly assigned to 8-wk working memory training, exergaming, or a wait-list control group. Each training course consisted of three 45-min training sessions per week. The primary outcome comprised the core executive functions (visual working memory, inhibition, switching), and the secondary outcomes included other cognitive domains (intelligence, planning, memory, attention, processing speed), motor abilities, and parent rating on their children's executive functions. Assessments were conducted both before and immediately after the interventions, and at 3-month follow-up. RESULTS: Linear mixed models revealed that participants in the working memory training group showed a linear improvement in visual working memory after training and at follow-up compared with the control group. No other intervention effects of either type of training could be detected. CONCLUSION: This study presents evidence that working memory training improves visual working memory in pediatric cancer survivors. Results show that near-transfer, but no far-transfer effects can be expected from working memory training. Multiple-component interventions tailored to fit the individual's cognitive profile are needed to best support cognitive development after cancer and its treatment.

The effect of exergaming on executive functions in children with ADHD: A randomized clinical trial.

BACKGROUND: Children with ADHD frequently suffer from deficits in cognitive (ie, executive functions) and motor abilities. Although medication usually has a positive effect, a lack of commitment and possible side effects result in a need for adjunct or alternative treatments. Thus, the aim of the current study was to investigate the effects of cognitively and physically demanding exergaming on executive functions, ADHD symptoms, and motor abilities. METHODS: In a parallel group randomized trial, 51 children between 8-12 years (M = 10.63; SD = 1.32) diagnosed with ADHD were assigned either to an 8-week exergame intervention group (three training sessions per week for 30 minutes) or a waiting-list control group. The core executive functions (inhibition, switching, updating), parent ratings of symptoms, and motor abilities were assessed/gathered before and after the intervention. RESULTS: Analyses of covariance (using pre-test values as covariates) revealed that children in the exergame intervention group improved in specific executive functions (reaction times in inhibition and switching), general psychopathology as well as motor abilities compared to control group. CONCLUSIONS: Findings indicate that exergaming might benefit two domains in which frequent deficits can be observed in children with ADHD, executive functions and motor abilities. Given that these beneficial effects in turn might positively affect psychopathology, exergaming could serve as an individualized home-based intervention in the future. However, in order to maximize benefits and make exergaming a valuable adjunct to treatment for children with ADHD, customized exergames are needed.

Boost your brain, while having a break! The effects of long-term cognitively engaging physical activity breaks on children's executive functions and academic achievement.

Classroom-based physical activity (PA) is gaining attention in terms of its potential to enhance children's cognitive functions, but it remains unclear as to which specific modality of PA affects cognitive functions most. The aim of the study was to examine the effects of qualitatively different PA breaks on children's cognitive outcomes. Children (N = 142) aged between 7 and 9 years were allocated to a 20-week classroom-based PA program, with either high physical exertion and high cognitive engagement (combo group), high physical exertion and low cognitive engagement (aerobic group), or low physical exertion and high cognitive engagement (cognition group). Executive functions (updating, inhibition, shifting) and academic achievement (mathematics, spelling, reading) were measured pre- and post-intervention. Results showed that the combo group profited the most displaying enhanced shifting and mathematic performance. The cognition group profited only in terms of enhanced mathematic performance, whereas the aerobic group remained unaffected. These results suggest that the inclusion of cognitively engaging PA breaks seem to be a promising way to enhance school children's cognitive functions.

A classroom intervention to improve executive functions in late primary school children: Too 'old' for improvements?

BACKGROUND: Given the strong relationship between executive functions and academic achievement, there has been great interest in improving executive functions. School-based group interventions targeting executive functions revealed encouraging results in preschoolers and young school children; however, there is a paucity of studies in older primary school children (age 10-12). This is surprising considering that deficits in executive function performance can often be observed in this age group. AIMS: Therefore, the aim of this study was to examine whether an innovative customized school-based group intervention could improve core executive functions (updating, inhibition, and shifting) in the age group concerned. SAMPLE: In total, 118 ten- to twelve-year-old school children were recruited from eight participating classes. METHODS: They were randomly assigned to one of two-six-week conditions of either a cognitive games group comprising of card and board games training executive functions (experimental group) or a wait-list control group (regular school lessons). In the cognitive games group, the class teachers held a 30-min training session twice a week. ANCOVAs (using pre-test values as covariate) were used to compare executive function performance between groups. RESULTS: Results revealed that the cognitive games group improved specific executive functions (updating and shifting) compared to the control group. These findings indicate that a school-based group intervention can improve executive functions, even in 'older' primary school children. CONCLUSION: This study provides empirical evidence for the effectiveness of a classroom-based cognitive training in older primary school children and is of practical relevance for educators.

Exergaming for Children and Adolescents: Strengths, Weaknesses, Opportunities and Threats.

Exergaming, or active video gaming, has become an emerging trend in fitness, education and health sectors. It is defined as digital games that require bodily movements to play, stimulating an active gaming experience to function as a form of physical activity (PA). Since exergaming is becoming more popular, claims have been made on the usefulness of exergaming. It has, for example, been entitled as being "the future of fitness" by the American College of Sports Medicine, promoting PA and health in children and adolescents. However, research also suggests that long-term engagement in exergaming is difficult to achieve, and there is a noticeable reservation towards exergaming by parents, teachers and caregivers. To provide an overview and to outline the future directions of exergaming, the aim of this review was to critically illustrate the strengths, weaknesses, opportunities and threats of exergaming to promote PA and health in children and youth. The available evidence indicates that exergaming has the potential to improve health via an increase in PA. However, it seems that this potential is frequently underexploited, and further developments such as customized exergames are needed.