Abstract: Composition and methods to prevent, inhibit or treat one or more symptoms of cystic fibrosis are provided.

Abstract: Voice-band signals are coupled to and from a telephone subscriber line via a low-pass filter which has a shunt capacitor coupled across the line. In order to simultaneously couple above voice-band signals to and from the line, this capacitor is coupled to the line via windings of a transformer. The above voice-band signals are coupled via the transformer to and from the line, for example via series inductors which are series resonant with the filter capacitor, as reflected through the transformer, at above voice-band signal frequencies. A parallel resonant circuit, which has a low impedance in the voice-band, is connected in parallel with a winding of the transformer to prevent degradation of the filter characteristics in the voice-band.

Abstract: Voice-band signals are coupled to and from a telephone subscriber line via a low-pass filter which has a shunt capacitor coupled across the line. In order to simultaneously couple above voice-band signals to and from the line, this capacitor is coupled to the line via windings of a transformer. The above voice-band signals are coupled via at least one series inductor and the transformer to the line, the inductor being series resonant with the filter capacitor, as reflected through the transformer, at the above voice-band signal frequency. Two such series inductors provide for efficient coupling of signals to and from the line at two different frequencies, facilitating simultaneous transmission and reception of above voice-band signals, for example FSK data signals, via the line. Parallel resonant circuits are also provided to prevent degradation of the filter characteristics in the voice-band and to prevent coupling of receive frequency components from the transmit signal to the receive signal line.

Abstract: A filter comprising reactive components which define pass and stop bands has the impedances of the components selected to minimize the sum .vertline.Zin-Z2.vertline.+.vertline.Zout-Z1.vertline. in the pass band, where Zin and Zout are respectively the input and output impedances of the filter and Z1 and Z2 are nominal termination impedance at respectively the input and output of the filter. The filter characteristic in the pass band is thereby made substantially independent of the actual termination impedances of the filter in use. The design is exemplified by a 5th order low pass filter for connection in the voice signal path of a telephone subscriber line.