Evropské druhy raků jsou stále vzácnější. Nemalou vinu na tom mají především raci introdukovaní ze Severní Ameriky a s nimi související šíření račího moru. Počet nepůvodních druhů v Evropě již dvakrát převyšuje původní račí faunu a v důsledku vysazování akvarijních druhů do volné přírody můžeme očekávat nálezy dalších račích přivandrovalců., European native crayfish species are on the decline. One of the key reasons is the introduction of invasive crayfish from North America and the associated spread of crayfish plague. The number of alien crayfish in Europe is already more than double the number of native species, and, due to the release of aquarium-kept specimens, we can expect discovery of additional ones., and Antonín Kouba, Adam Petrusek.
Novikov superalgebras are related to quadratic conformal superalgebras which correspond to the Hamiltonian pairs and play a fundamental role in completely integrable systems. In this note we show that the Novikov superalgebras with $A_0=A_1A_1$ and $\dim A_1=2$ are of type $N$ and give a class of Novikov superalgebras of type $S$ with $A_0=A_1A_1$.
Cookbooks are currently a very popular literary genre in the field of gastronomy, but this was not always the case. Until the end of the 19th century, cookbooks were intended only for wealthy middle-class female readers. The study tries to show that the situation changed at the beginning of the 20th century, and cookbooks that were unprecedented before 1900 appeared. Their authors began to focus on particular groups of diners, types of ingredients, and different ways of eating. They also aimed at lower social classes, such as the working class and the countryside. The first cookbooks inspired by foreign gastronomy or the new dietary phenomenon – vegetarianism – were also produced. The development was also influenced by several historical events, such as World War I, when several war cookbooks were written. The female authors of cookbooks are an important aspect in the research on gastronomy. They are no longer just experienced housewives who share their recipes and advice, but include women dealing with education, and health and food science. Some of the authors‘ names are still well-known today.