Abstract: The invention is based on the finding that the secretin receptor is expressed in tissues present in the distal lung of humans. In patient with asthma, levels of the receptor are elevated compared to normal tissue. Treatment of tissue by secretin stimulates the movement of negative ions in the tissue. Addition of secretin to human bronchial tissue in vitro stimulates bronchorelaxation. The invention provides methods of treatment of asthma in a patient by administering to said patient an effective amount of an agent which triggers anion efflux and bronchorelaxation in respiratory tissue via the activation of a secretin receptor.

Abstract: A variable diameter rotor for a tilt rotor aircraft has an inboard section having a linear twist from a root end to an outboard end thereof, and an outboard section telescoped over the inboard section which additionally has a linear twist from a root end to an outboard end thereof. The outboard section is disposed at an offset of about 4.degree. to 15.degree. relative to the inboard section to provide a step wise change in twist angle when in the extended condition, such that the rotor when operated in the helicopter mode, can be operated at high blade pitch angles without premature stalling along the inboard airfoil surfaces This allows efficient operation at high thrust coefficient/solidarity ratios. Optionally, the trailing edge of the outboard section is rotated along the aft 30% of chord of the airfoil section to provide an equivalent twist increase in the offset at the transition between the blade sections.

Abstract: A traveling wave tube (10) includes a coupled cavity type slow wave structure (100) having a driver stage (52) and an output section (101) with a primary section (64) and a velocity taper section (82) which in combinattion produce maximum signal gain at a predetermined frequency. A gain flattening section (104) is preferably disposed between the driver stage (52) and the primary section (64) of the output section (101), and is designed to operate at a reduced phase velocity selected to produce minimum or negative signal gain at approximately the predetermined frequency. The gain characteristics of the driver stage (52), gain flattening section (104), primary section (64), and velocity taper section (82) combine to produce minimum signal gain variation over an operating frequency range which spans the predetermined frequency, and expand the bandwidth of the traveling wave tube (10).

Abstract: A traveling-wave tube (10) has a confined-flow periodic permanent magnet focusing arrangement (26) in which either the first magnet (60f) or the third magnet (60t) from the electron gun (12) has an extent or axial thickness along the electron stream path which is one-half that of the remaining magnets in the arrangement, thereby providing a scalar magnetic potential of essentially zero on the electron gun pole piece (46), thereby eliminating the field reversal at the cathode (14). This enables a magnetic field to be provided in the region of the electron gun between the gun pole piece (46) and a location behind the cathode due solely to the magnetic field leaking through the gun pole piece aperture (50). The axial magnetic field within the electron gun (12) may be tailored or fine tuned, by varying the size of the aperture (50) in the gun pole piece (46).