Search

Background Pulmonary hypertension (PH) is often caused by left heart disease (group 2 PH) , which is difficult to diagnose early and with a high mortality rate. Potassium channel dysfunction is a marker of PH, however, the epidemiological data of the disease and the effect of potassium ions on PH still remain unclear. Objective To investigate the correlation of serum potassium level with myocardial markers, echocardiographic indicators and length of hospital stay in patients with group 2 PH, and evaluate the predictive value of serum potassium levels for the severity of group 2 PH, so as to provide the oretical basis for clinical diagnosis and treatment. Methods The clinical data of 400 adult inpatients diagnosed with group 2 PH in the First Hospital of Shanxi Medical University from January 2020 to December 2021 were retrospectively collected as follows: (1) general data: gender, age, BMI, length of hospital stay, smoking status, smoking index (SI) and drinking history; (2) underlying diseases (diabetes mellitus, hypertension) ; (3) laboratory data: serum potassium level, myocardial markers[procalcitonin, N-terminal pro-brain natriuretic peptide (NT-proBNP) , cardiac troponin I, cardiac troponin T, creatine kinase-MB], echocardiographic indicators (left atrial diameter, right ventricular diameter, right atrial area, left ventricular ejection fraction, shortening fraction, peak tricuspid regurgitation velocity, pulmonary artery systolic pressure) . The patients were divided into 5.5 mmol/L group (n=3) according to the serum potassium level. Spearman correlation analysis was used to explore the correlation of serum potassium level with myocardial markers and echocardiographic indicators. Log-rank (Mantel-Cox) test was used to compare the discharge rate of patients with different serum potassium levels. Receiver operating characteristic curve (ROC curve) was plotted to evaluate the predictive value of serum potassium level for the severity of group 2 PH. Results Procalcitonin and NT-proBNP levels of patients in the >5.5 mmol/L group were significantly higher than the 5.5 mmol/L to investigate its relationship with length of hospital stay in depth. Log-rank (Mantel-Cox) testresults showed that for group 2 PH patients greater than average hospitalization levels, there was a significant difference in cumulative hospitalization rates among patients with different serum potassium levels (5.5 mmol/L) (P=0.022) . ROC analysis showed that the diagnostic value of serum potassium level for non-mild PH (AUC=0.577, cut-off value=3.91 mmol/L, sensitivity=64.7%, specificity=52.5%) was similar to that of NT-proBNP (AUC=0.585, cut-off value=1 070.69 pg/mL, sensitivity=78.1%, specificity=39.6%) , which can effectively predict the severity of group 2 PH. Conclusion Serum potassium level can predict the severity of group 2 PH and the length of hospital stay. Intervention of serum potassium levels may be one of the new approach to prevent and treat PH.

Carrier tracking loop is a basic method of frequency tracking in CEI (connected element interferometry), but the tracking error is very large or even worse at high dynamic. To solve this problem, a frequency tracking method assisted by open loop frequency estimation is proposed in this paper. First, an open-loop frequency estimation algorithm is used to estimate the frequency of signals at different moments, then, the least squares fitting method is used to estimate the corresponding dynamic parameters of different orders. Next, a local signal is generated to compensate the received signal. After eliminating most of the dynamic characteristics, the signal is fed into PLL (Frequency locked loop) and high-precision frequency tracking results can be obtained. Simulation results show that, in the condition of low SNR, the new method has higher accuracy than the method assisted by FLL (Frequency locked loop), and the processing time is shorter. When there is a two order Doppler frequency change, the open-loop assisted method can overcome the steady phase error of the PLL, and is of great significance in the applications of connected elements interferometry.

In order to describe the near space communication channel efficiently and analyse the the reasons that cause quality deterioration of ground-to-air communication link, design the Channel modelling program of the near space and establish the near space channel model based on the DS signal system which considers rain attenuation and multipath fading. Complete the analysis of rainfall impact on signal fading and estimate related parameters under different elevation. Set up the statistical model of multipath fading. Complete the simulation of Ka-band geostationary near space channel performance under different elevation. Draw bit error rate performance simulation curve under different weather conditions. The result of MATLAB simulation shows that the model can reflect the fading characteristic of the near space communication channel. This program improves the signal fading and interference tolerance. The findings can provide a better simulation Platform for the follow-up job according to the correctness and practicability of established model and be of great significance in exploration and research of near space communication.