Conductivity and noise problem of plasma antennas
Investigation the plasma antenna on the basis of UHF discharge near the second Langmuir resonance (subresonance) is continuing. Measurements are given on the admission of signals. It is provied reducing the thermal and fluctuation noise of UHF discharge compared with metal.
Plasma antennas based on UHF discharge
Studied are the antenna properties of the UHF discharge plasma at the threshold of the resonance of the electron Langmuir frequency with the pump second harmonic. The results of experimental measurements of some characteristics of a plasma antenna-amplifier at the LF range are shown. A mathematical model of a similar antenna, which allows proceeding to a physical model of the distributed parametric amplifier, is built.
Thrombus formation after aortic valvular replacement using Björk-Shiley valve occluding the right coronary orifice.
We describe a patient with unstable angina due to occlusion of the orifice of the right coronary artery by thrombus formation after aortic valvular replacement using a Björk-Shiley valve. After strict anticoagulant treatment, transesophageal echocardiography demonstrated disappearance of the thrombus formation around the orifice of the right coronary artery.