Voice type in baroque operas. Except for a few very rare voices (such as the American male soprano Michael Maniaci or singers with a disorder such as Kallmann syndrome), singers called countertenors generally sing in the falsetto register, sometimes using their modal voice for the lowest notes. Historically, there is much evidence that the countertenor, in England at least, also designated a very high tenor voice, the equivalent of the French "haute-contre". Until about 1830, all male voices used some falsetto-type voice production in their upper range. Countertenor voices span a broad range, covering E3 to E5. Countertenor subtypes: Countertenors are often
Conventional superconductor Conventional superconductor Conventional superconductors are materials that display superconductivity as described by BCS theory or its extensions. This is in contrast to unconventional superconductors, which do not. Conventional superconductors can be either type-I or type-II. Most elemental superconductors are conventional. Niobium and vanadium are type-II, while most other elemental superconductors are type-I. Critical temperatures of some elemental superconductors: Most compound and alloy superconductors are type-II materials. The most commonly used conventional superconductor in applications is a niobium-titanium alloy - this is a type-II superconductor with a superconducting critical temperature of 11 K. The highest critical temperature so far achieved in