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This paper proposes a novel transmit waveform design method of multiple input multiple output (MIMO) dual functional radar communication (DFRC) system based on an optimal constellation, which takes into account the waveform diversity advantages of MIMO radar in view of the competition between electronic information devices for spatial spectrum resource. Firstly, we constructed an optimization design model for the transmit waveform of the MIMO-DFRC system is constructed. Secondly, the communication information embedding strategy is designed based on the joint constraint of communication signal of amplitude and phase. Simultaneously, the constellation of the expected communication signal to further reduce the bit error rate (BER) of communication information transmission is optimized, which efficiently solved the BER by utilizing the sequential linear programming algorithm based on the first-order Taylor expansion (SLP-FTE). As the designed waveform can achieve the integrated functions of radar target detection and communication information transmission simultaneously, it can effectively solve the problem of spectrum congestion. Finally, the simulation analysis verifies the effectiveness of the proposed method. [ABSTRACT FROM AUTHOR]

In bistatic spaceborne High-Resolution Wide-Swath SAR systems (HRWS-SAR), the azimuth reconstruction to obtain a uniform sampling signal or Doppler spectrum is a crucial step in image processing because azimuth signals are generally of non-uniform sampling type. In this study, the variant transmitting distance to receiving distance radio is approximated to be a constant, the equivalence between the bistatic and monostatic SAR azimuth interchannel transfer functions is deduced, and the azimuth signal model in spaceborne HRWS-SAR with general bistatic configuration is established. Furthermore, the matrix inversion algorithm to reconstruct the azimuth signal is proposed; in addition, to measure the reconstruction performance, the formulae for the signal noise ratio scaling factor and the azimuth ambiguity signal ratio are provided. The azimuth reconstruction is simulated in several spaceborne HRWS-SAR systems with typical bistatic configuration, and the results show that the azimuth Doppler spectrum can be correctly reconstructed via the matrix inversion algorithm when the azimuth sampling is conducted without coinciding samples.

Objective: To investigate the safety and effectiveness of low-dose tranexamic acid (TXA) in operation of multi-level continuous thoracic ossification of ligament flavum (TOLF)., Methods: A clinical data of 26 patients who underwent operation for multi-level continuous TOLF and met the selection criteria between July 2015 and January 2019 was retrospectively analyzed. Among them, 13 cases (group A) were received intravenous infusion of TXA (10 mg/kg) at 15 minutes before operation, and maintained the infusion at 1 mg/(kg·h) until the end of the operation; 13 cases (group B) were received the same dose of normal saline before and during operation. There was no significant difference in gender, age, body mass index, diseased segment, and preoperative hemoglobin, platelet count, activated partial thromboplastin time, prothrombin time, international normalized ratio (INR) between the two groups ( P >0.05). The hemoglobin, platelet count, activated partial thromboplastin time, prothrombin time, INR, the number of deep vein thrombosis of the lower extremities, operation time, intraoperative blood loss, postoperative drainage volume, total blood loss, and the time of drainage tube extubation in the two groups were recorded and compared., Results: All operations in the two groups were successfully completed. Compared with group B, the operation time and time of drainage tube extubation in group A were shortened, and the intraoperative blood loss, postoperative drainage volume, and total blood loss were reduced. The differences between the two groups were significant ( P <0.05). None of the two groups received blood transfusion, and the hemoglobin level of group A at 24 hours after operation was significantly higher than that of group B ( t =5.062, P =0.000). The incisions in both groups healed and sutures were removed within 2 weeks after operation, and no complications occurred. There was no significant difference between the two groups in activated partial thromboplastin time, prothrombin time, INR, and platelet count at 24 hours after operation ( P >0.05)., Conclusion: In multi-level continuous TOLF operation, intravenous administration of low-dose TXA can effectively reduce blood loss, shorten postoperative drainage time, and does not increase the risk of complications.

In this report, highly water soluble esters of scutellarin with different molecular weight polyethylene glycol (PEG) were synthesized in order to improve the bioavailability of scutellarin. The physicochemical properties, the stabilities under different conditions and the in situ intestinal absorption in rats of the conjugates were investigated. By PEG modification, the greatly increased water solubility and desirable partition coefficient of scutellarin were obtained. These compounds function as prodrugs i. e. breakdown occurred in a predictable fashion: the t1/2 of them in PBS buffer at pH7.4 was above 12 h (37 degrees C) in vitro, while in plasma a rapid breakdown was observed, with a t1/2 of about 1. 5-3 h. The stabilities of the prodrugs were improved according to the increase of the molecular weight of PEG, thus, PEGylated prodrugs with desirable rates of hydrolysis could be obtained by the use of variable molecular weight PEGs. The PEGylation could enhance the absorption of scutellarin in rat intestine, and the absorption of scutellarin and its PEG conjugates by intestine was mainly via passive transport, for when the concentration was raised, the uptake did not appear saturable, and the permeability coefficient kept at an equilibrium level. When the molecular weight of PEG increased from 200 to 1000 Da, the absorption of the conjugates decreased. In conclusion, by overall consideration of the yield, stability and absorption, the present authors estimate that the PEG molecular weight used for the PEGylation of scutellarin should be within the range of 400-1 000 Da.