Context and question: In 1931, RCA Victor introduced their vinyl-based Victrolac compound as a material for some unusual-format and special-purpose records. By the end of the 1930s vinyl's advantages of light weight, relative unbreakability and low surface noise had made it the material of choice for prerecorded radio programming and other critical applications. When it came to ordinary 78 rpm records, however, the much higher cost of the raw material, as well as its vulnerability to the heavy pickups and crudely mass-produced steel needles still commonly used in home record players, made its general substitution for shellac impractical at that time. During the Second World War, the United States Armed Forces produced thousands of 12-inch vinyl 78 rpm V-Discs for use by the troops overseas. After the war, the wider use of vinyl became more practical as new record players with relatively lightweight crystal pickups and precision-ground styli made of sapphire or an exotic osmium alloy proliferated. In late 1945, RCA Victor began offering special transparent red vinyl De Luxe pressings of some classical 78s, at a de luxe price. Later, Decca Records introduced vinyl Deccalite 78s, while other record companies came up with vinyl concoctions such as Metrolite, Merco Plastic and Sav-o-flex, but these were mainly used to produce "unbreakable" children's records and special thin vinyl DJ pressings for shipment to radio stations.
What were advantages of vinyl in the 1930's?
Answer: light weight, relative unbreakability and low surface noise
Context and question: Holes through a PCB are typically drilled with small-diameter drill bits made of solid coated tungsten carbide. Coated tungsten carbide is recommended since many board materials are very abrasive and drilling must be high RPM and high feed to be cost effective. Drill bits must also remain sharp so as not to mar or tear the traces. Drilling with high-speed-steel is simply not feasible since the drill bits will dull quickly and thus tear the copper and ruin the boards. The drilling is performed by automated drilling machines with placement controlled by a drill tape or drill file. These computer-generated files are also called numerically controlled drill (NCD) files or "Excellon files". The drill file describes the location and size of each drilled hole.
What's another name for NCD files that has an "x" in it?
Answer: Excellon files
Context and question: Phaininda and episkyros were Greek ball games. An image of an episkyros player depicted in low relief on a vase at the National Archaeological Museum of Athens appears on the UEFA European Championship Cup. Athenaeus, writing in 228 AD, referenced the Roman ball game harpastum. Phaininda, episkyros and harpastum were played involving hands and violence. They all appear to have resembled rugby football, wrestling and volleyball more than what is recognizable as modern football. As with pre-codified "mob football", the antecedent of all modern football codes, these three games involved more handling the ball than kicking. Non-competitive games included kemari in Japan, chuk-guk in Korea and woggabaliri in Australia.
What is the name of a similar, non-competitive game in Japan called?
Answer:
kemari