Abstract: An improved lithographic printing plate and a process for production thereof, involving exposure to light, development, and burning-in treatment of a presensitized printing plate precursor, are disclosed, the improvement comprising applying an aqueous solution containing at least one compound selected from the group consisting of malic acid and salts thereof onto the printing plate precursor prior to the burning-in treatment; by the improvement, a lithographic printing plate having excellent printing durability can be produced.

Abstract: A signal sending control system for use in a telephone system includes a ringing signal sending circuit having a signal source for generating a continuous ringing signal, interrupting means for controlling the sending of the ringing signal over each subscriber line, one switch for each subscriber line for selectively and switchably connecting the respective subscriber line to a speech network of the system and to the ringing signal sending circuit, a common controller for providing control information as to the duration of the ringing signal, and a control circuit for individually controlling the switching circuit of each subscriber line in accordance with the control information and for controlling the transmission duration of the ringing signal.