Objective To observe the effects and the mechanism of the thoracic pressure variation on the velocity of tricuspid regurgitation in quiet respiration, to accurately estimate the pulmonary artery systolic pressure,and to verify the new proposed mechanism of respiration effects on hemodynamics using echocardiography. Methods Continuous-wave Doppler spectra of tricuspid regurgitation were recorded with Sequoia 512 in 50 patients who had stable tricuspid regurgitation. Electrocardiogram and respiratory tracing were recorded simultaneously. The velocities and the pressure gradients were recorded during different respiration phases for analyzing. Results Respiration reliably affected on tricuspid regurgitant velocity. There were three patterns of manifestation:①The velocity increased in the inspiratory phase. ②The velocity decreased in the inspiratory phase. ③The velocity changed randomly. Conclusions Thoracic pressure variations had definite effects on the velocity of tricuspid regurgitation and tricuspid gradient. This research indicated that to obtain accurate and reliable Doppler echocardiographic measurement of the pulmonary artery systolic pressure, the measurement should be at the time between inspiration and expiration.

Objective To investigate the interferences of the variations in the blood pressure and vasoreactivity to the parameters of arterial elasticity via cold pressor test(CPT) in healthy young men. Methods The wave intensities(WI) of the right common carotid artery(RCCA) in twenty-two healthy young men during CPT were measured by echo-tracking technique. The parameters of arterial elasticity, including stiffness parameter (β),pressure-strain etastic modulus(Ep), arlerial compliance(AC),augument index(AI) , pulse wave veloctiy-β (PWVβ),and pulse wave velocity_WI(PWV_WI) from WI analysis during CPT were recorded and statistically compared with the baseline data. Results During CPT, the heart rates increased slightly ( P <0. 05) and the mean arterial pressures increased obviously ( P <0. 05); As to the parameters of arterial elasticity, the Ep,AI, PWVβ,and PWV_WI increased obviously ( P <0. 05), AC decreased ( P <0. 05), while the (3 didn't change. Conclusions The β is affected little by the blood pressure and vasoreactivity, and can reflect the actual arterial elasticity; while the Ep, AC, AI, PWVβ, and PWV_WI are affected much by blood pressure and vasoreactivity. When the latter parameters are used to evaluate the arterial elasticity, the interferences of variations in blood pressure and vasoreactivity must be excluded.

Objective To develop a portable nuclear radiation detector with low-energy γ-nuclide recognition capability for rapid measurement of the dose levels in low-energy radiation fields and identification of nuclides. Methods A digital multi-channel circuit was developed for a detector based on the room temperature semiconductor cadmium zinc telluride, nuclide recognition was achieved using an intelligent nuclide recognition algorithm, and the energy response function G(E) was used to calculate the real-time ambient dose equivalent rate H*(10). Results The portable spectrometer had a minimum detectable energy of 20 keV, and the typical energy resolution for low-energy X-rays was > 4.10% at 59.5 keV and 20℃, enabling accurate identification of ²⁴¹Am nuclide. Conclusion The device has a good measurement performance for low-energy γ/X rays, effectively addressing the limitations of existing devices for monitoring low-energy radiation fields, and provide reliable technical methods for monitoring and emergency response in spent fuel reprocessing plants or nuclear material production plants.