Numerical investigation of the energy performance of a guideless irregular heat and mass exchanger with corrugated heat transfer surface for dew point cooling

© 2016 The Author(s) The paper presents an investigation into the energy performance of a novel irregular heat and mass exchanger for dew point cooling which, compared to the existing flat-plate heat exchangers, removed the use of the channel supporting guides and implemented the corrugated heat transfer surface, thus expecting to achieve the reduced air flow resistance, increased heat transfer area, and improved energy efficiency (i.e. Coefficient of Performance (COP)) of the air cooling process. CFD simulation was carried out to determine the flow resistance (K) factors of various elements within the dry and wet channels of the exchanger, while the ‘finite-element’ based ‘Newton-iteration’ numerical simulation was undertaken to investigate its cooling capacity, cooling effectiveness and COP at various geometrical and operational conditions. Compared to the existing flat-plate heat and mass exchangers with the same geometrical dimensions and operational conditions, the new irregular exchanger could achieve 32.9%–37% higher cooling capacity, dew-point and wet-bulb effectiveness, 29.7%–33.3% higher COP, and 55.8%–56.2% lower pressure drop. While undertaking dew point air cooling, the irregular heat and mass exchanger had the optimum air velocity of 1 m/s within the flow channels and working-to-intake air ratio of 0.3, which allowed the highest cooling capacity and COP to be achieved. In terms of the exchanger dimensions, the optimum height of the channel was 5 mm while its length was in the range 1–2 m. Overall, the proposed irregular heat and mass exchanger could lead to significant enhanced energy performance compared to the existing flat-plate dew point cooling heat exchanger of the same geometrical dimensions. To achieve the same amount cooling output, the irregular heat and mass exchanger had the reduced size and cost against the flat-plate ones

School physical activity intervention effect on adolescents' performance in mathematics

Purpose: The primary aim of this study was to test the effect of a school-based physical activity intervention on adolescents’ performance in mathematics. A secondary aim was to explore potential mechanisms that might explain the intervention effect. Methods: The Activity and Motivation in Physical EDucation intervention was evaluated using a two-arm cluster randomized controlled trial in 14 secondary schools located in low socioeconomic areas of Western Sydney, Australia. Study participants (n = 1173) were grade 8 students (mean age = 12.94 yr, SD = 0.54). The multicomponent intervention was designed to help teachers maximize students’ opportunities for moderate-to-vigorous physical activity (MVPA) during physical education (PE) and enhance students’ motivation toward PE. Mathematics performance was assessed as part of national testing in grade 7, which was the year before the trial began and then again in grade 9. Potential mediators were: (i) proportion of PE lesson time that students spent in MVPA and leisure time MVPA (%), measured using Actigraph GT3X+ accelerometers, and (ii) students’ self-reported engagement (behavioral, emotional, and cognitive) during mathematics lessons. Mediators were assessed at baseline (grade 8) and follow-up (grade 9, 14–15 months after baseline). Results: The effect of the intervention on mathematics performance was small-to-medium (β = 0.16, P < 0.001). An intervention effect was observed for MVPA% in PE (β = 0.59, P < 0.001), but not for leisure time MVPA or any of the engagement mediators. There were no significant associations between changes in potential mediators and mathematics performance. Conclusions: The Activity and Motivation in Physical EDucation intervention had a significant positive effect on mathematics performance in adolescents. However, findings should be interpreted with caution as the effect was small and not associated with changes in hypothesized mediators

Infant and young child feeding practices among adolescent mothers and associated factors in India

Adequate infant and young child feeding (IYCF) improve child survival and growth. Globally, about 18 million babies are born to mothers aged 18 years or less and have a higher likelihood of adverse birth outcomes in India due to insufficient knowledge of child growth. This paper examined factors associated with IYCF practices among adolescent Indian mothers. This cross-sectional study extracted data on 5148 children aged 0–23 months from the 2015–2016 India National Family Health Survey. Survey logistic regression was used to assess factors associated with IYCF among adolescent mothers. Prevalence of exclusive breastfeeding, early initiation of breastfeeding, timely introduction of complementary feeding, minimum dietary diversity, minimum meal frequency, and minimum acceptable diet rates were: 58.7%, 43.8%, 43.3%, 16.6%, 27.4% and 6.8%, respectively. Maternal education, mode of delivery, frequency of antenatal care (ANC) clinic visits, geographical region, child’s age, and household wealth were the main factors associated with breastfeeding practices while maternal education, maternal marital status, child’s age, frequency of ANC clinic visits, geographical region, and household wealth were factors associated with complementary feeding practices. IYCF practices among adolescent mothers are suboptimal except for breastfeeding. Health and nutritional support interventions should address the factors for these indicators among adolescent mothers in India

Individual differences in lexical and grammar spelling across primary school

To successfully spell in an inconsistent orthography like French, students must learn to negotiate not only lexical spelling but grammatical spelling, too, with morphological markers that are often silent. We sought to examine different acquisition profiles, based on children's lexical and grammatical spelling development in Grades Three and Five. We used latent profile analysis to examine the relationship between lexical and grammatical spelling development in primary schoolchildren in France, by asking 244 children third and fifth graders to complete a series of tasks assessing their lexical and grammatical spelling performances. The latent profile analysis revealed different groups of spellers who differentially managed lexical and grammatical spelling, and more individual differences in spelling performances in Grade Three than in Grade Five. These findings are discussed in the light of previous findings on spelling development in nontransparent orthographies, in terms of different profiles in learning and mastering written language

A multidimensional model of school dropout from an 8-year longitudinal study in a general high school population

This study tests an empirical multidimensional model of school dropout, using data collected in the first year of an 8-year longitudinal study, with first year high school students aged 12–13 years. Structural equation modeling analyses show that five personal, family, and school latent factors together contribute to school dropout identified at 19 years of age: poor parent–teenager relationships, youth depression and family difficulties, negative classroom climate, negative school interactions, and poor academic achievement. This model increases our understanding of the dropout process in the general population and has direct implications for the development of high school dropout prevention programs

Effects of a Dual-Approach Instruction on Students’ Science Achievement and Motivation

The aim of the present study was to investigate the effects of an intervention on students’ achievement and motivation. The intervention was in the form of an instructional approach named Dual-Approach Instruction since it was designed to facilitate both the cognitive and non-cognitive aspects of students’ learning. The intervention effects were assessed through a cluster-level assignment design, which compared the control and intervention groups’ achievement and motivational outcomes. A total of seven teachers and 427 grade 7 students participated in this study. Four teachers were assigned to the intervention condition and participated in a series of workshops on Dual-Approach Instruction. These teachers then applied the intervention to two topics, Speed and Density, with 231 students. The rest of the teachers and students were in the control group. Multiple regression analyses of students’ achievement and motivation pre-test and post-test scores indicated that the intervention had a significant effect on students’ achievement in complex problem solving, as well as in the following six motivational attributes: self-regulation, engagement, sense of competence, task goal orientation, education aspiration, and career aspiration in science. The results suggest that Dual-Approach Instruction benefits students in terms of dual outcomes: science achievement and motivation

Applying Big Data Methods to Understanding Human Behavior and Health

While many fields have benefited greatly from the collection and analysis of big data, some health fields and, to a large extent, psychology are still lagging behind (Azmak et al., 2015). Azmak et al. (2015) have shown an example (e.g., Sloan Digital Sky) on how the collection of large datasets has aided researchers to solve difficult problems in astronomy that were not possible in the past. Interestingly, the slow process of applying big data to psychology mirrors the history of development of sciences, as astronomy and other sciences are much older than experimental psychology (which emerged in the nineteenth century). This is related to the fact that while many sciences are data-driven, psychology, to a large degree, is hypothesis-driven (see below discussion on these points)

Factors associated with adherence to the muscle-strengthening activity guideline among adolescents

Purpose We aimed to explore associations between guideline-concordant muscle-strengthening activity (MSA) and demographic, biological, psychosocial, and behavioral factors among Australian adolescents. Methods We used baseline data from the ‘Resistance Training for Teens’ cluster randomized controlled trial (collected April–June 2015). Adolescents (n = 602, mean age = 14.1 ± 0.5 years, 50% female) from 16 schools in New South Wales, Australia self-reported their sex, primary language spoken at home, postal code (for socioeconomic status), resistance training (RT) self-efficacy, motivation for RT, perceived strength, moderate-to-vigorous physical activity (MVPA), screen-time, and sleep. Participants also completed tests of height, weight, cardiorespiratory and muscular fitness, flexibility, and RT skills. MSA was self-reported and participants were dichotomized as ‘meeting’ (3–7 days) or ‘not meeting’ (0–2 days) the MSA guideline. Binary logistic regression with odds ratios (OR) was used to determine associations with adolescents' MSA. Results Analyses for each variable group explained a small-to-moderate proportion of the variance in MSA. Sex, muscular fitness, RT self-efficacy, perceived strength, and total MVPA emerged as statistically significant factors. However, only RT self-efficacy (OR = 2.48 [1.37 to 4.50]) and total MVPA (OR = 1.48 [1.22 to 1.79]) were associated with guideline-concordant MSA in the full model, which explained 52% of the variance. Conclusions Our study adds to the limited understanding of adolescents' MSA behavior. RT self-efficacy and total MVPA were independently associated with guideline-concordant MSA among Australian adolescents. The findings have implications for the design and delivery of future interventions targeting adolescents’ MSA behavior

Mediating effects of sleep on mental health in older adolescents : Findings from the Burn 2 Learn randomized controlled trial

Purpose Our study explored the mediating effect of sleep-related variables on older adolescents' mental health in the context of a school-based physical activity intervention. Methods We evaluated the Burn 2 Learn (B2L) intervention using a cluster randomized controlled trial, which included two cohorts. Participants for this sub-study were from the second cohort, which included 292 older adolescents (16.0 ± 0.5 years) from 10 secondary schools in New South Wales, Australia. Teachers at intervention schools delivered two high-intensity activity breaks (approximately 10 mins) per week to students during academic lessons. Participants completed measures of mental health (i.e., perceived stress and internalizing problems) and hypothesized mediators (i.e., sleep duration, sleep latency, awakenings, and daytime sleepiness) at baseline (February–April 2019) and post-intervention (August–September 2019). Single mediation analyses were conducted to explore the potential mediating effects of sleep variables on mental health outcomes using a product-of-coefficient test. Results We observed a small statistically significant effect for perceived stress (β = −0.11, SE = 0.034, p = 0.002), but not for internalizing problems (β = 0.02, SE = 0.051, p = 0.760). There were no significant intervention effects for sleep-related variables. Several sleep-related variables were associated with mental health outcomes but no mediated effects were found. Conclusion The B2L intervention had a small beneficial effect on perceived stress, however our mediation analyses suggest this was not explained by changes in sleep-related variables. Markers of sleep were associated with mental health constructs, highlighting the importance of sleep for good psychological health. However, in the context of a physical activity intervention, effects on mental health may be driven by other behavioral, neurobiological, or psychosocial mechanisms.peerReviewe