In more recent years, the Guinness company has permitted the franchising of small museums with displays based on the book, all currently (as of 2010 [update] ) located in towns popular with tourists: Tokyo , Copenhagen , San Antonio . There were once Guinness World Records museums and exhibitions at the London Trocadero , Bangalore , San Francisco , Myrtle Beach , Orlando ,  Atlantic City , New Jersey,  and Las Vegas , Nevada .  The Orlando museum, which closed in 2002, was branded The Guinness Records Experience ;  the Hollywood, Niagara Falls , Copenhagen, and Gatlinburg , Tennessee museums also previously featured this branding. 
The Calling of St Matthew (1599-1600) San Luigi dei Francesi.
The Martyrdom of St Matthew (1599-1600) San Luigi dei Francesi.
Conversion on the way to Damascus (1601) Santa Maria del Popolo.
Crucifixion of St Peter (1601) Santa Maria del Popolo, Rome.
Death of the Virgin (1601-6) Louvre, Paris.
The Entombment of Christ (1601-3) Vatican Museums, Rome.
The accepted explanation for the pulsation of Cepheids is called the Eddington valve ,  or κ-mechanism , where the Greek letter κ (kappa) denotes gas opacity. Helium is the gas thought to be most active in the process. Doubly ionized helium (helium whose atoms are missing both electrons) is more opaque than singly ionized helium. The more helium is heated, the more ionized it becomes. At the dimmest part of a Cepheid's cycle, the ionized gas in the outer layers of the star is opaque, and so is heated by the star's radiation, and due to the increased temperature, begins to expand. As it expands, it cools, and so becomes less ionized and therefore more transparent, allowing the radiation to escape. Then the expansion stops, and reverses due to the star's gravitational attraction. The process then repeats.