Neodymium is a chemical element with the symbol Nd and atomic number 60. It is the fourth member of the lanthanide series and is considered to be one of the rare-earth metals. It is a hard, slightly malleable, silvery metal that quickly tarnishes in air and moisture. When oxidized, neodymium reacts quickly producing pink, purple/blue and yellow compounds in the +2, +3 and +4 oxidation states. It is generally regarded as having one of the most complex spectra of the elements. Neodymium was discovered in 1885 by the Austrian chemist Carl Auer von Welsbach, who also discovered praseodymium. It is present in significant quantities in the minerals monazite and bastnäsite. Neodymium is not found naturally in metallic form or unmixed with other lanthanides, and it is usually refined for general use. Neodymium is fairly common—about as common as cobalt, nickel, or copper—and is widely distributed in the Earth's crust. Most of the world's commercial neodymium is mined in China, as is the case with many other rare-earth metals. Neodymium compounds were first commercially used as glass dyes in 1927 and remain a popular additive. The color of neodymium compounds comes from...

Deep operation (Russian: Глубокая операция, glubokaya operatsiya), also known as Soviet Deep Battle, was a military theory developed by the Soviet Union for its armed forces during the 1920s and 1930s. It was a tenet that emphasized destroying, suppressing or disorganizing enemy forces not only at the line of contact but also throughout the depth of the battlefield. The term comes from Vladimir Triandafillov, an influential military writer, who worked with others to create a military strategy with its own specialized operational art and tactics. The concept of deep operations was a national strategy, tailored to the economic, cultural and geopolitical position of the Soviet Union. In the aftermath of several failures or defeats in the Russo-Japanese War, First World War and Polish–Soviet War, the Soviet High Command (Stavka) focused on developing new methods for the conduct of war. This new approach considered military strategy and tactics, but also introduced a new intermediate level of military art: operations. The Soviet Union was the first country to officially distinguish the third level...

A pan flute (also known as panpipes or syrinx) is a musical instrument based on the principle of the closed tube, consisting of multiple pipes of gradually increasing length (and occasionally girth). Multiple varieties of pan flutes have been popular as folk instruments. The pipes are typically made from bamboo, giant cane, or local reeds. Other materials include wood, plastic, metal and ivory. Name The pan flute is named after Pan, the Greek god of nature and shepherds, often depicted with such an instrument. The pan flute has become widely associated with the character Peter Pan created by Sir James Matthew Barrie, whose name was inspired by the god Pan.In Greek mythology, Syrinx (Σύριγξ) was a forest nymph. In her attempt to escape the affection of god Pan (a creature half goat and half man), she was transformed into a water-reed or calamos (cane-reed). Then, Pan cut several reeds, placed them in parallel one next to the other, and bound them together to make a melodic musical instrument. Ancient Greeks called this instrument Syrinx, in honour of the Muse, and Pandean, or Pan-pipes and Pan-flute, after...

National Donut Day or National Doughnut Day, celebrated in the United States and in some other countries, is on the first Friday of June of each year, succeeding the doughnut event created by The Salvation Army in Chicago in 1938 to honor those of their members who served doughnuts to soldiers during World War I. The holiday celebrates the doughnut. Many American doughnut stores offer free doughnuts on the occasion. History National Donut Day started in 1938 as a fundraiser for Chicago's The Salvation Army. Their goal was to help those in need during the Great Depression, and to honor the Salvation Army "Lassies" of World War I, who served doughnuts to soldiers. Soon after the entrance of the United States into World War I in 1917, the Salvation Army sent a fact-finding mission to France. The mission concluded that the needs of American enlisted men could be met by canteens/social centers termed "huts" that could serve baked goods, provide writing supplies and stamps, and provide a clothes-mending service. Typically, six staff members per hut would include four female volunteers who...

Metadata (or metainformation) is "data that provides information about other data", but not the content of the data, such as the text of a message or the image itself. There are many distinct types of metadata, including: Descriptive metadata – the descriptive information about a resource. It is used for discovery and identification. It includes elements such as title, abstract, author, and keywords. Structural metadata – metadata about containers of data and indicates how compound objects are put together, for example, how pages are ordered to form chapters. It describes the types, versions, relationships, and other characteristics of digital materials. Administrative metadata – the information to help manage a resource, like resource type, permissions, and when and how it was created. Reference metadata – the information about the contents and quality of statistical data. Statistical metadata – also called process data, may describe processes that collect, process, or produce statistical data. Legal metadata – provides information about...

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