Meta-analysis of the influence of gender and age on the seasonal dynamics of cerebral strokes

The purpose of this work is to investigate dependence of the seasonal dynamics of HS (hemorrhagic strokes) and IS (ischemic strokes) risk on sex and age using meta-analysis. In total, 22 publications were selected for this meta-analysis, studying the seasonal dynamics of HS, of which 8 publications presented statistics separately for men and women, and three papers presented statistics for different age groups. Also, 28 publications studying the seasonal dynamics of IS were selected for meta-analysis, of which 11 publications presented statistics separately for men and women, and three papers presented statistics for different age groups. The meta-analysis of the seasonal dynamics of HS showed that HS risk is less likely in a warmer season compared with a colder one. In men, HS risk was the highest in winter and spring, and in women in winter. Dependence between HS risk and a decrease in air temperature was the same in men and women. According to the results of the meta-analysis (without regard to sex and age), the minimum probability of IS occurs in autumn. In women, IS risk was significantly higher in winter compared to other seasons. In men, the seasonal dynamics of IS was not expressed. In older people, the overall risk of stroke increased, especially IS. In people over 65 years of age, there was a significant dependence of an increase in HS risk on a decrease in air temperature. In people younger than 65 years, HS risk was not associated with cold. A decrease in temperature equally increased IS risk in both age groups. These results suggest that sex and age may influence the seasonal stroke risk

Hunting French ducks in population dynamics

Equations with periodic coefficients for singularly perturbed growth can be analysed by using fast and slow timescales in the framework of Fenichel geometric singular perturbation theory and its extensions. The analysis is restricted to one-dimensional time-periodic ordinary differential equations and shows the presence of slow manifolds, canards and the dynamical exchanges between several slow manifolds. There exist permanent (or periodic) canards and periodic solutions containing canards