Abstract: The invention concerns a positive pressure nasal breathing apparatus in which a processed air flow is supplied at positive pressure to the person to be treated. The apparatus comprises: a first device (10) for producing a first air flow which has a given first temperature and a first degree of relative air humidity; and a second device (12) for processing the first air flow such that a second air flow to be completely or partially supplied to the person is produced. The temperature of the second air flow is lower and its degree of relative air humidity higher than that of the first air flow.

Abstract: In a method for the electrical measurement of the concentration of acids a measurement electrode (11) consisting at least predominantly of crystalline graphite is arranged in an acid (12) having anions which form graphite intercalation compounds with graphite. The measurement electrode (11) is then intercalated by generating in the measurement electrode (11), at a variable positive potential, a current of such a size that the anions of the acids (12) can from graphite intercalation compounds with the graphite. The current is maintained until the intercalation compounds have formed at the surface. The potential at the measurement electrode (11) is then measured and used as a measure for the acid concentration. The measurement electrode (11) is subsequently deintercalated again.

Abstract: First and second branches, each containing two thyristors in series, all four thyristors of same polarity, are connected across positive and negative supply lines, in turn connected to positive and negative terminals of D.C. voltage source. D.C. motor connected between junction of two thyristors in one branch and junction of two thyristors in other branch. One pair of diagonally opposite thyristors, or other pair of diagonally opposite thyristors, rendered conductive, for flow of motor current in respective first or second direction. First and second transistors respectively connected in positive and negative supply lines to permit and interrupt thyristor current flow. Selection of a thyristor pair for conduction occurs based on sense of motor-current error. The transistors and selected two thyristors rendered conductive and non-conductive by pulse-width-modulated actuating signal derived from value of motor-current error.

Abstract: The movement of a template past a stylus is controlled by furnishing desi velocity signals to first and second motors driving the template along two mutually perpendicular axes. Two wheatstone bridge strain gauge arrangements, one for each axis, and energized by quadrature voltages furnish signals which are combined in a summing amplifier to yield a signal having an amplitude and angular deflection corresponding to that of the stylus. The signal is rectified yielding a signal corresponding to the amplitude of stylus deflection and is further used to synchronize a sawtooth wave generator in accordance with the angle of deflection. The sawtooth wave output and the amplitude signal output are compared and when equal set a monostable multivibrator which closes two switches each sampling the output of one of the quadrature voltage generators energizing the strain gauges.