In optics, a dichroic material is either one which causes visible light to be split up into distinct beams of different wavelengths (colours) (not to be confused with dispersion), or one in which light rays having different polarizations are absorbed by different amounts. In beam splitters The original meaning of dichroic, from the Greek dikhroos, two-coloured, refers to any optical device which can split a beam of light into two beams with differing wavelengths. Such devices include mirrors and filters, usually treated with optical coatings, which are designed to reflect light over a certain range of wavelengths and transmit light which is outside that range. An example is the dichroic prism, used in some camcorders, which uses several coatings to split light into red, green and blue components for recording on separate CCD arrays, however it is now more common to have a Bayer filter to filter individual pixels on a single CCD array. This kind of dichroic device does not usually depend on the polarization of the light. The...

The Lycurgus Cup is a 4th-century Roman glass cage cup made of a dichroic glass, which shows a different colour depending on whether or not light is passing through it: red when lit from behind and green when lit from in front. It is the only complete Roman glass object made from this type of glass, and the one exhibiting the most impressive change in colour; it has been described as "the most spectacular glass of the period, fittingly decorated, which we know to have existed".The cup is also a very rare example of a complete Roman cage-cup, or diatretum, where the glass has been painstakingly cut and ground back to leave only a decorative "cage" at the original surface-level. Many parts of the cage have been completely undercut. Most cage-cups have a cage with a geometric abstract design, but here there is a composition with figures, showing the mythical King Lycurgus, who (depending on the version) tried to kill Ambrosia, a follower of the god Dionysus (Bacchus to the Romans). She was transformed into a vine that twined around the enraged king and restrained him, eventually killing him. Dionysus and two followers are shown taunting the king. The cup is the...

The Danza de los Voladores (Spanish pronunciation: [ˈdansa ðe los βolaˈðoɾes]; "Dance of the Flyers"), or Palo Volador (pronounced [ˈpalo βolaˈðoɾ]; "flying pole"), is an ancient Mesoamerican ceremony/ritual still performed today, albeit in modified form, in isolated pockets in Mexico. It is believed to have originated with the Nahua, Huastec and Otomi peoples in central Mexico, and then spread throughout most of Mesoamerica. The ritual consists of dance and the climbing of a 30-meter (98 ft 5 in) pole from which four of the five participants then launch themselves tied with ropes to descend to the ground. The fifth remains on top of the pole, dancing and playing a flute and drum. According to one myth, the ritual was created to ask the gods to end a severe drought. Although the ritual did not originate with the Totonac people, today it is strongly associated with them, especially those in and around Papantla in the Mexican...

Avocado toast is a type of open sandwich consisting of toast with mashed avocado, and any of a variety of spices and flavorful ingredients. The most popular are usually salt and black pepper, sometimes lemon juice or other citrus, while others include olive oil, hummus, vinegar, red pepper flakes, feta, duqqa and tomato. Avocado toast became a food trend of the 2010s. It has appeared on café menus since at least the 1990s. Following avocado toast's elevation to trend status, the act of ordering avocado toast at a café was criticized as a symbol of frivolous spending. Origins Avocados are a native fruit of the Americas with their likely origin being Central Mexico. The trees and fruit have been cultivated by pre-Columbian civilizations from South Central Mexico for nearly 9,000 years.Sliced or mashed avocado has been eaten on some sort of bread, flatbread, or tortilla (often heated or toasted) since humans first started consuming bread and avocados, and before any documented or written history. In Chile avocado on marraqueta or "pan con palta" or "tostadas con palta" is a common traditional...