Scarce swallowtail Republic have been found to be a good indicator of relatively well preserved xerothermic grassland habitats with forest-steppe vegetation, which have no cutting history. In some years the scarce swallowtail is quite abundant. The scarce swallowtail is getting rarer as the blackthorn bushes are being cleared. The butterfly is now protected by law in the Czech Republic, Slovakia, Germany, Hungary, Luxembourg, Russia, Ukraine and Poland. It is considered rare and endangered and protected in some provinces of Austria and of indeterminate status throughout Europe. In Armenia the species demonstrates stable population trend and is evaluated as Least Concern. Though referred
Pythagorean comma Pythagorean comma In musical tuning, the Pythagorean comma (or ditonic comma), named after the ancient mathematician and philosopher Pythagoras, is the small interval (or comma) existing in Pythagorean tuning between two enharmonically equivalent notes such as C and B (), or D and C. It is equal to the frequency ratio (1.5)/128 = about 1.01364, or about 23.46 cents, roughly a quarter of a semitone (in between 75:74 and 74:73). The comma which musical temperaments often refer to tempering is the Pythagorean comma. The Pythagorean comma can be also defined as the difference between a Pythagorean apotome and a Pythagorean