The Effects of Age, Biological Maturation and Sex on the Development of Executive Functions in Adolescents

The development of executive functions (EF) has been widely investigated and is associated with various domains of expertise, such as academic achievement and sports performance. Multiple factors are assumed to influence the development of EF, among them biological maturation. Currently the effect of biological maturation on EF performance is largely unexplored, in contrast to other domains like physical development or sports performance. Therefore, this study aimed (a) to explore the effect of chronological age on EF performance and (b) to investigate to what extent age-related changes found in EF are affected by biological maturation on both sexes. To this end, EF performance and degree of maturity, indexed by percentage of predicted adult height (%PAH), of 90 adolescents (11–16 years old, 54% males) were measured on three occasions in a time frame of 12 months. A Generalized Estimating Equation (GEE) approach was used to examine the association between chronological age and %PAH and the weighted sum scores for each EF component (i.e., inhibition, planning, working memory, shifting). All models were run separately for both sexes. The males’ results indicated that EF performance improved with age and degree of maturity on all four components. Interaction effects between age and %PAH on inhibition showed that at a younger age, males with a higher %PAH had a lower chance of performing well on inhibition, whereas at later ages, males with a higher %PAH had a higher chance to have a good inhibition performance. For working memory, it seems that there is no maturity effect at a younger age, while at later ages, a disadvantage for later maturing peers compared to on-time and earlier maturing male adolescents emerged. Females showed slightly different results. Here, age positively influenced EF performance, whereas maturity only influenced inhibition. Interaction effects emerged for working memory only, with opposite results from the males. At younger ages, females with lower %PAH values seem to be scoring higher, whereas at later ages, no maturity effect is observed. This study is one of the first to investigate the effect of biological maturation on EF performance, and shows that distinct components of EF are influenced by maturational status, although the effects are different in both sexes. Further research is warranted to unravel the implications for maturation-driven effects on EF that might significantly affect domains of human functioning like academic achievement and social development.

Evaluation of Maturity and Odor Emissions in the Process of Combined Composting of Kitchen Waste and Garden Waste

With the development of urbanization, kitchen waste and garden waste have become an important part of municipal solid waste (MSW), which is in urgent need of resource treatment. This study investigated the impacts of garden waste as auxiliary materials on maturity and odor emissions (NH3 and H2S) during kitchen waste composting. The result showed that the combined composting product of kitchen waste and garden waste achieved the maturity effect, and the co-composting effect was better than that of separate composting of kitchen waste. Meanwhile, compared with the separate composting treatment of kitchen waste, the co-composting treatment of kitchen waste and garden waste can effectively reduce the cumulative emissions of H2S by more than 85%, and effectively reduce the cumulative emissions of NH3 by more than 75%. This study provides a technical reference for the green fertilizer utilization of kitchen waste and garden waste.

Oestrus synchronization efficiency in ewes and ram maturity effect on fertility during summer season

The purpose of this study was to investigate oestrus synchronization efficiency and ram maturity effect on fertility of ewes of MIS sheep population during summer season. Research was performed on the experimental sheep farm of the Institute for Animal Husbandry in Belgrade, Serbia. The study included 70 crossbred ewes of MIS sheep population (Pirot Pramenka, Merinolandschaf and Ile de France breed) and 3 Ile de France rams (2 young, sexually unexperienced rams and 1 mature ram). Oestrus was synchronized in all 70 ewes using progestagen impregnated vaginal sponges (30 mg fluorogestone acetate) in combination with 500 IU PMSG. Ewes were mated with rams 48 h later. Obtained fertility and productivity results were as follows: lambing rate 57.14% (40/70), gestation length 147.11, litter size 1.82, stillborn rate 15.07%, birth weight of lambs 4.29 kg and body weight of lambs at 30 days of age 13.07 kg on average. Based on the results obtained in this study it was concluded that presented oestrus synchronization and mating protocol yielded lower than expected lambing rate. The effect of ram maturity on lambing rate was significant (P<0.05), as ewes mated to mature ram had higher lambing rate compared to those mated to two young unexperienced rams. Mature ram also had bigger litter size and higher stillborn rate, as well as lower birth weight of lambs.

High Propensity to Pay Dividends By State-Controlled Companies in Poland. Tunneling or Maturity Effect?

Usage of a random effects panel logit model have shown in this paper that the high propensity to pay dividends by the state-controlled companies quoted on the Warsaw Stock Exchange over the last years was not a result of the tunneling effect but was the maturity effect. The state-controlled companies which pay dividends fulfil the maturity effect criteria as they are big, profitable, have low investment opportunities and financial leverage, and are characterised by low risk associated with investing in their shares. The additional evidence of a reasonable and stable dividend policy pursued by the state-controlled companies are: payout ratio on the level of slightly more than 50% and lower by almost 8 percentage points than in the other companies; and relatively rare use of the reserve capital for dividends. However, state-controlled companies listed on the WSE are mostly commercial and of a fiscal nature for the state, which may create a temptation for tunneling.