Experiences Situating Mathematical Problem Solving at the Core of Early Childhood Classrooms

Our goal in this article is to discuss the importance of problems in early childhood education for the child’s development and engagement with the mathematics existing in childhood culture. Our assumption is that an important task for young children’s education is to create a democratic and critical environment, in which multiplicity of perspectives is celebrated, along with diversity of concepts and practices, with movement between imaginary and real worlds. In light of this, the goal of this article is to defend a perspective for curriculum and for the role of the mathematics educator, promoting the learning of mathematics through problem solving in early childhood years. In order to discuss and illustrate this perspective we describe the pedagogical practices of two teachers who teach 4- and 5-years-olds, who create for their students an environment rich in problem solving and investigations. In both classrooms, all children individually succeeded in sharing their unique solutions and new knowledge constructed as a result of their inquiries. The experience provides evidence that problem solving affords children the opportunity to raise conjectures, to discuss possibilities and to draw conclusions, even if partial ones, that are then vetted by the group as the authors share their solutions. In this way, the work with problem solving nurtures cooperative learning and promotes the exploration of a diversity of ideas.     

Effect of biological maturation on maximal oxygen uptake and ventilatory thresholds in soccer players: An allometric approach

Abstract

In this study, we investigated the effect of biological maturation on maximal oxygen uptake ([Vdot]O_2max) and ventilatory thresholds (VT₁ and VT₂) in 110 young soccer players separated into pubescent and post-pubescent groups.. Maximal oxygen uptake and [Vdot]O₂ corresponding to VT₁ and VT₂ were expressed as absolute values, ratio standards, theoretical exponents, and experimentally observed exponents. Absolute [Vdot]O₂ (ml · min^?1) was different between groups for VT₁, VT₂, and [Vdot]O_2max. Ratio standards (ml · kg^?1 · min^?1) were not significantly different between groups for VT₁, VT₂, and [Vdot]O_2max. Theoretical exponents (ml · kg^?0.67 · min^?1 and ml · kg^?0.75 · min^?1) were not properly adjusted for the body mass effects on VT₁, VT₂, and [Vdot]O_2max. When the data were correctly adjusted using experimentally observed exponents, VT₁ (ml · kg^?0.94 · min^?1) and VT₂ (ml · kg^?0.95 · min^?1) were not different between groups. The experimentally observed exponent for [Vdot]O_2max (ml · kg^?0.90 · min^?1) was different between groups (P = 0.048); however, this difference could not be attributed to biological maturation. In conclusion, biological maturation had no effect on VT₁, VT₂ or [Vdot]O_2max when the effect of body mass was adjusted by experimentally observed exponents. Thus, when evaluating the physiological performance of young soccer players, allometric scaling needs to be taken into account instead of using theoretical approaches.     

Open-domain conversational search assistants: the Transformer is all you need

Information Retrieval Journal - On the quest of providing a more natural interaction between users and search systems, open-domain conversational search assistants have emerged, by assisting users...     

Impact of compliance with different guidelines on physical activity during pregnancy and perceived barriers to leisure physical activity

Abstract

The aims of the this prospective study were to analyse physical activity (PA) engagement during the first and second trimesters, considering the different guidelines published on PA, to document the individual characteristics associated with the accomplishment of these guidelines and to examine pregnant women’s perceived barriers to leisure PA, using a socioecological framework. A sample of 133 pregnant women in two stages – at 10–12 weeks’ gestation (T1) and 20–22 weeks’ gestation (T2) – were evaluated. PA was assessed by accelerometry during the T1 and T2 evaluation stages. Socio-demographic characteristics, lifestyle factors and barriers to leisure PA were assessed via questionnaire. A large proportion of women (ranging from 32% to 96%) did not reach the levels of PA recommended by the guidelines. There were no significant differences between T1 and T2 with regard to compliance with PA recommendations. A decrease in PA levels from T1 to T2 was noted for all recommendations. No associations were found between participants’ characteristics and adherence to the recommendations in T1 and T2. No significant differences were found in barriers to leisure PA between T1 and T2. The most commonly reported barriers to leisure PA were intrapersonal, not health related. Our results indicate that there were no differences between trimesters regarding compliance of PA recommendations, and perceived barriers were similar in both trimesters.     

Classes of developmental trajectories of body mass index: Differences in motor competence and cardiorespiratory fitness

ABSTRACT

The purpose was to identify classes of different developmental trajectories of BMI and testing them for differences in motor competence (MC) and cardiorespiratory fitness (CRF), in children and adolescents (4 to 13 years of age). This was a 5 years’ longitudinal study with six cohorts. One hundred and forty-seven children (69 girls) divided into six cohorts participated. At baseline, the youngest and the oldest cohorts had 4 and 11 years of age, respectively. Height and weight were assessed, and BMI was calculated. MC was assessed with KTK and TGMD-2, and CRF was assessed with one-mile run/walk. Developmental trajectories of BMI were identified using latent class linear-mixed modelling. Latent class membership was explained according to covariates of MC and CRF. Two meaningful classes were identified. Class 1 (78.92% of the participants) showed lower initial BMI and a lower slope compared to class 2 (21.08% of the participants) (all ps < 0.001). Class membership only predicted trajectories in motor coordination, with children in class 1 having a better development.

In conclusion, this study identified two meaningful trajectories for children based on their BMI development across five time points. In line with previous research, children with slower increasing BMI showed better motor coordination improvements.     

Association between socio-economic status and physical activity is mediated by social support in Brazilian students

This study evaluated whether the relationship between socioeconomic status (SES) and moderate-to-vigorous physical activity (MVPA) is mediated by social support of peers and parents. A cross-sectional study included students (n = 1182) aged 11 to 18 years who were recruited in 2014 from public schools in Fortaleza, Brazil. Participants completed a questionnaire to assess all variables. Mediation analyses were performed to determine the role of parental support and peer support on the relationship between SES and MVPA. Also, moderated-mediation analyses with estimating of conditional indirect effects were performed in order to identify whether gender is a moderator of the mediating effect. A positive and significant association between SES and MVPA was found among Brazilian students, and social support of parents and peers were significant mediators of this relationship. Conditional indirect effects showed that both parental and peer support had a significant indirect effect among boys; only parental support had a significant indirect effect among girls. These results suggest that improving social support can help reduce the impact of SES on physical activity among Brazilian adolescents.     

Self-controlled amount of practice benefits learning of a motor skill

Self-control over factors involving task-related information (e.g, feedback) can enhance motor learning. It is unknown if these benefits extend to manipulations that do not directly affect such information. The purpose of this study was to determine if self-control over the amount of practice would also facilitate learning Participants learned to throw a dart using their nonpreferred hand. The self-control (SC) group decided when to stop practice. The yoked group completed the same number of trials as their SC counterparts. Results revealed the SC group was more accurate during transfer and in recalling the number of trials completed. These findings indicate that self-control benefits extend to factors that do not directly alter task-related information.     

Does intensity really matter regarding aerobic exercise reductions in wave reflection and central hemodynamics? Commentary on "The effect of acute aerobic exercise on central arterial stiffness,wave reflections,and hemodynamics in adults with diabetes: A randomized cross-over design"by Way et al.

We read with great interest the study by Way et al.1 pub-lished in this journal, which described and compared the acute changes in central arterial stiffness (A...     

Robust asymptotic stability of interval fractional-order nonlinear systems with time-delay

This paper studies the global asymptotic stability of a class of interval fractional-order (FO) nonlinear systems with time-delay. First, a new lemma for the Caputo fractional derivative is presented. It extends the FO Lyapunov direct method allowing the stability analysis and synthesis of FO nonlinear systems with time-delay. Second, by employing FO Razumikhin theorem, a new delay-independent stability criterion, in the form of linear matrix inequality is established for ensuring that a system is globally asymptotically stable. It is shown that the new criterion is simple, easy to use and valid for the FO or integer-order interval neural networks with time-delay. Finally, the feasibility and effectiveness of the proposed scheme are tested with a numerical example.