Hayk Mirzayans Insect Museum offers training courses, and helps other scientific research centers in completion and maintenance of their insect collections. ITRD acts as the National Identification Service for governmental or non-governmental organizations, publishes various articles, reports, books, data banks and checklists of its holdings, and provides these information free of charge to all visitors. Hayk Mirzayans Insect Museum The Hayk Mirzayans Insect Museum (HMIM) is the largest insect collection in Iran with over 4 million insect specimens, including 20–25,000 local species, hundreds of primary types and paratypes, and a representative collection of exotic insects, especially tropical butterflies. In 1943, Iranian entomologist established a
Syntonic comma Johnston uses a "−" as an accidental to indicate a note is lowered by a syntonic comma, or a "+" to indicate a note is raised by a syntonic comma. Thus a Pythagorean scale is C D E+ F G A+ B+, while the 5-limit Ptolemaic scale is C D E F G A B. Syntonic comma In music theory, the syntonic comma, also known as the chromatic diesis, the comma of Didymus, the Ptolemaic comma, or the diatonic comma is a small comma type interval between two musical notes, equal to the frequency ratio 81:80 (= 1.0125) (around 21.51