question: Which instrument is Clara Rockmore a virtuoso of in the novel Us Conductors?
answer: the theremin
context: Title: Virtuoso
  Passage: A virtuoso (from Italian "virtuoso" ] or ] , "virtuous", Late Latin "virtuosus", Latin "virtus", "virtue", "excellence", "skill", or "manliness") is an individual who possesses outstanding technical ability in a particular art or field such as fine arts, music, singing, playing a musical instrument, or composition.  This word also refers to a person who has cultivated appreciation of artistic excellence, either as a connoisseur or collector.  The plural form of "virtuoso" is either virtuosi or the Anglicisation, virtuosos, and the feminine forms are virtuosa and virtuose.
  Title: Hans von Bülow
  Passage: Baron Hans Guido von Bülow (January 8, 1830February 12, 1894) was a German conductor, virtuoso pianist, and composer of the Romantic era.  One of the most famous conductors of the 19th century, his activity was critical for establishing the successes of several major composers of the time, especially Richard Wagner and Johannes Brahms.  Alongside Carl Tausig, Bülow was perhaps the most prominent of the early students of Hungarian virtuoso pianist, conductor and composer Franz Liszt – therein performed the first public performance of Liszt's Sonata in B minor in 1857.  He became acquainted with, fell in love and eventually married Liszt's daughter Cosima, who later left him for Wagner.  Noted for his interpretation of the works of Ludwig van Beethoven, he was one of the earliest European musicians to tour the United States.
  Title: Us Conductors
  Passage: Us Conductors is a debut novel by Canadian writer Sean Michaels.  Published in 2014 by Random House in Canada and Tin House in the United States, the novel is a fictionalized account of the relationship between Léon Theremin (also known as Lev Termen), the inventor of the theremin, and Clara Rockmore, the musician regarded as the instrument's first virtuoso player.
  Title: The Art of the Theremin
  Passage: The Art of the Theremin is the first official album by theremin virtuoso Clara Rockmore, and the only one released in her lifetime.  It was produced by Robert Moog and his first wife, Shirleigh Moog, and was released as an LP in 1977 by Delos International Records.  As with most of her live performances, she was accompanied minimally by her older sister, Nadia Reisenberg, on piano.  The 1977 Delos LP and 1981 Japanese Delos LP release were entitled "Theremin".  The 1987 Delos CD was titled "The Art of the Theremin".
  Title: Clara Rockmore
  Passage: Clara Rockmore (née Reisenberg, March 9, 1911 – May 10, 1998) was a classical violin prodigy and a virtuoso performer of the theremin, an electronic musical instrument.  She was the sister of pianist Nadia Reisenberg.
  Title: Jean-Baptiste Arban
  Passage: Joseph Jean-Baptiste Laurent Arban (28 February 1825 – 8 April 1889) was a cornetist, conductor, composer, pedagogue and the first famed virtuoso of the "cornet à piston" or valved cornet.  He was influenced by Niccolò Paganini's virtuosic technique on the violin and successfully proved that the cornet was a true solo instrument by developing virtuoso technique on the instrument.
citations: Us Conductors Clara Rockmore