A tiny terrestrial snail Vertigo geyeri is an example of a typical late-glacial relict in the central Europe. It inhabits exclusively treeless fens and is highly endangered in most of its area and internationally protected. So far, only three recent and highly isolated populations have been found in the Czech Republic. The first one, a small calcareous spring fen located in the V Dubech Nature Monument was however damaged by construction of drainage canals and summer droughts in the last few years and the future survival of this population is doubtful. New sites found in 2011 (the Louky u Jeníkova NM and the Ratajské rybníky NM) document that the species is still extant in the Czech Republic at more sites than previously thought., Jan Myšák, Michal Horsák, Jaroslav Č. Hlaváč., and 4 barev. fot.
The article tackles the phenomenon of the one-child family in the Czech Republic. The authors try to answer the question of whether it is possible to expect that a significant proportion of Czech fertility intentions will be fulfilled when families conceive and give birth to an only child. Can it be assumed that one-child families will be a significant phenomenon in Czech society in the years to come? To answer the questions the authors used two different datasets in the analysis. The article includes a description of the socio-demographic characteristics of people who have or intend to have just one child. They then proceed to present some of the covariates that determine whether people have or intend to have one child in comparison with those who have other fertility intentions. Some of the findings indicate that it is likely that about 20-25% of women who finish their reproductive period within the next two decades will have only one child. The results indicate that being an only child increases the chances of intending to and having only one child. The opposite effect can be noticed when the place of residence is considered - living in small towns and rural areas may have a negative influence on the decision to have only one child.
V tomto příspěvku věnovanému úlohám z fyzikálních olympiád se zaměříme na velmi moderní oblast fyziky - částicovou fyziku. Ukážeme dva příklady úloh, jejichž společným jmenovatelem je kvarkový model mezonu. Modely jsou natolik jednoduché, že je možné je řešit prostředky středoškolské fyziky., Jan Kříž, Ivo Volf, Bohumil Vybíral., and Obsahuje seznam literatury