Microliter-bioreactor array with buoyancy-driven stirring for human hematopoietic stem cell culture

This work presents the development of an array of bioreactors where finely controlled stirring is provided at the microliter scale (100–300 μl). The microliter-bioreactor array is useful for performing protocol optimization in up to 96 parallel experiments of hematopoietic stem cell (HSC) cultures. Exploring a wide range of experimental conditions at the microliter scale minimizes cost and labor. Once the cell culture protocol is optimized, it can be applied to large-scale bioreactors for stem cell production at the clinical level. The controlled stirring inside the wells of a standard 96-well plate is provided by buoyancy-driven thermoconvection. The temperature and velocity fields within the culture volume are determined with numerical simulations. The numerical results are verified with experimental velocity measurements using microparticle image velocimetry (μPIV) and are used to define feasible experimental conditions for stem cell cultures. To test the bioreactor array’s functionality, human umbilical cord blood-derived CD34⁺ cells were cultured for 7 days at five different stirring conditions (0.24–0.58 μm∕s) in six repeated experiments. Cells were characterized in terms of proliferation, and flow cytometry measurements of viability and CD34 expression. The microliter-bioreactor array demonstrates its ability to support HSC cultures under stirred conditions without adversely affecting the cell behavior. Because of the highly controlled operative conditions, it can be used to explore culture conditions where the mass transport of endogenous and exogenous growth factors is selectively enhanced, and cell suspension provided. While the bioreactor array was developed for culturing HSCs, its application can be extended to other cell types.     

Associations and indirect effects between LEGO® construction and mathematics performance

There is a known association between LEGO® construction ability and mathematics achievement, yet the mechanisms which drive this association are largely unknown. This study investigated the spatial mechanisms underlying this association, and whether this differs for concrete versus digital construction. Between January 2020 and July 2021, children aged 7–9 years (N = 358, 189 female, ethnicity not recorded) completed spatial and mathematics tasks, and either a concrete or digital Lego construction task. Mediation analyses examining direct and indirect pathways (through spatial skills) between Lego construction ability and mathematics explained 8.4% to 26.6% of variance in mathematics scores. Exploratory moderated mediation analyses revealed that only the indirect path through mental rotation differed between Lego conditions. Findings are discussed in relation to theories of spatial-numerical associations and the potential of Lego training for mathematics improvement.     

Teaching toddlers the meaning of numbers—connecting modes of mathematical representations in book reading

Educational Studies in Mathematics - In this article, we direct attention to what becomes critical in teaching activities for toddlers (1–3-year-olds) to learn the meaning of numbers. One...     

Teachers' Understanding of the Role of Executive Functions in Mathematics Learning

Cognitive psychology research has suggested an important role for executive functions, the set of skills that monitor and control thought and action, in learning mathematics. However, there is currently little evidence about whether teachers are aware of the importance of these skills and, if so, how they come by this information. We conducted an online survey of teachers' views on the importance of a range of skills for mathematics learning. Teachers rated executive function skills, and in particular inhibition and shifting, to be important for mathematics. The value placed on executive function skills increased with increasing teaching experience. Most teachers reported that they were aware of these skills, although few knew the term “executive functions.” This awareness had come about through their teaching experience rather than from formal instruction. Researchers and teacher educators could do more to highlight the importance of these skills to trainee or new teachers.     

Personal and situational factors influencing coaches’ perceptions ofstress

Abstract

Coaching has been recognised as a demanding occupation, associated with a range of stressors. The extent to which coaches perceive stress is likely to be influenced by various personal and situational factors. The purpose of this study was to identify coaches' levels of perceived stress and examine the personal and situational factors that may influence coaches' perceptions of stress. In total, 502 coaches working with university, college, Canada Games, and/or nationally identified athletes completed this study. Coaches completed an online survey, which included questions regarding demographics, work/job-related considerations, and aspects relating to their contract. Coaches also completed the Perceived Stress Scale (Cohen, Kamarck, & Mermelstein, 1983 Cohen, S., Kamarck, T. and Mermelstein, R. 1983. A global measure of perceived stress. Journal of Health and Social Behavior, 24: 385–396. [Crossref], [PubMed], [Web of Science ®] , [Google Scholar]). Overall coaches indicated slightly below average levels of perceived stress (M = 15.13 out of 40) compared with norm-values (Cohen & Janicki-Deverts, 2012 Cohen, S. and Janicki-Deverts, D. 2012. Who's stressed? Distributions of psychological stress in the United States in probability samples from 1983, 2006, and 2009. Journal of Applied Social Psychology, 42: 1320–1334. [Crossref], [Web of Science ®] , [Google Scholar]). Demographic factors, job-related characteristics, and certain aspects of their contract were associated with coaches' perceptions of stress. In particular, unclear expectations, long-working hours (>40), lack of agreed evaluation criteria, higher salaries, and a lack of social support were related to higher perceptions of stress. As such, the findings of the current study indicate that a reduction in perceived stress is likely to be achieved through a multifaceted approach that addresses multiple factors associated with coaching.     

The effects of individual or group guidelines on the calibration accuracy and achievement of high school biology students

A 2 × 2 factorial design was employed in a quasi-experiment to investigate the effects of guidelines in group or individual settings on the calibration accuracy and achievement of 82 high school biology students. Significant main effects indicated that calibration practice with guidelines and practice in group settings increased prediction and postdiction accuracy. A significant interaction showed that students who practiced calibration in groups using guidelines showed the greatest accuracy in their predictions and postdictions. Students in the guidelines condition and in the group setting condition had significantly higher achievement scores. The findings of this study suggest that the use of guidelines and group settings can promote calibration accuracy and achievement in high school biology courses.     

Why do children not play in nearby nature? Results from a Norwegian survey

Based on a nationwide Norwegian survey among 3160 parents of children aged 6–12 years, this article identifies and discusses barriers for children’s engagement with nearby nature. A set of social factors related to time pressure are evaluated as more significant barriers than environmental factors such as accessibility, safety and landscape quality. Children’s free play in nearby nature does not seem to be an alternative to a target-orientated and time-scheduled everyday life. Instead, parents give themselves, other adults and public institutions more responsibility to stimulate increased nature contact. Despite strong traditions in outdoor life and good accessibility to nearby nature, social and cultural trends seem to influence children’s engagement with nature in the same way in ‘Green Norway’ as it does in many other European countries. Implications of the findings are discussed in terms of policy and promotion according to nature management and adults’ roles.