A barrier device and technique for use in the plumbing during construction of a swimming pool includes a tubular cylindrical section having an open first end. The single-arm bail of the unlocking and resetting device can return the start position automatically without manual repositions. The optical waveguide may sense at least one parameter distributed along the drill string. The p+-type impurity region has a higher impurity concentration than the p-type well and is shallower than the p-type well. Also a method for improving the learning or memory of a normal subject is suggested, said method comprising the administering of phanquinone, optionally together with one or more pharmaceutically acceptable carrier. If there is no password present, the email is scanned and the sender is notified that, for a fee, the email can be forwarded to the user.