GaoFen-3, the first polarimetric SAR satellite of China, carried out polarimetric calibration experiments using C-band polarimetric active radar calibrators (PARCs), trihedral corner reflectors (TCRs), and dihedral corner reflectors (DCRs). The calibration data were firstly processed referring to the classic 2 × 2 receive R and transmit T model for radar polarimeter systems, first proposed by Zebker, Zyl, and Held, and Freeman’s method based on PARCs, but the results were not good enough. After detailed analysis about the GaoFen-3 polarimetric system, we found that the system had some nonlinearity, then a new imbalance parameter was introduced to the classic model, which is equivalent to the γ proposed in Freeman’s paper about a general polarimetric system model. Then, we proposed the calibration data processing algorithm for GaoFen-3 based on the improved model and obtained better results. The algorithm proposed here is verified to be suitable for GaoFen-3 and can be applied to other spaceborne and airborne fully-polarimetric SAR systems.
CUEDC2, a newly reported protein, plays critical roles in many biological processes, such as cell cycle, inflammation and tumorigenesis, however, its expression in ovarian serious carcinoma is still poorly understood. In this study, we performed an immunohistochemical study on 101 cases of ovarian serous carcinoma tissues to investigate whether CUEDC2 is a useful biomarker to evaluate the progression of ovarian serous carcinomas. The data showed that the overexpression of CUEDC2 was observed in 59.4% of ovarian serous carcinoma tissue samples and correlated with histopathological grade, patient age at diagnosis, FIGO stage and recurrence. To assess the clinical relevance of CUEDC2, we analyzed the survival follow-up information, the results showed that CUEDC2-positive expression was associated with a shorter disease-free survival time, the median disease-free survival time of CUEDC2-positive patients was 36.0 months compared with 53.9 months of CUEDC2-negative ones (Log-rank χ2=6.149, P=0.013). Collectively, our results suggested that CUEDC2 may be a promising biomarker to evaluate the progression of serous ovarian carcinoma and to predict likely relapse of ovarian serous carcinoma.
Chemoresistance remains an obstacle to the successful treatment of ovarian carcinoma. CUE domain-containing 2 (CUEDC2) plays critical roles in tumor genesis and overexpresses in many solid cancers, including ovarian serous carcinoma. In previous study, we found that overexpression of CUEDC2 might be a promising biomarker to evaluate the progression and to predict likely relapse of serous ovarian carcinoma. In present study, we found that higher expression of CUEDC2 was associated with higher resistance to cisplatin. The overall survival (OS) and disease-free survival time (DFS) of patients with cisplatin resistant was shorter than that of those with cisplatin sensitive, respectively, and the cisplatin sensitivity was independent predictor of a shorter OS time and DFS time. Knockdown of CUEDC2 by small interfering RNA enhanced the cisplatin sensitivity of serous ovarian carcinoma cells in SKOV3 cell lines. Furthermore, the phosphorylation of p38 MAPK were obviously increased after CUEDC2 knockdown, while p38 MAPK signaling contributes to cell growth and cell apoptosis. Our data suggest that CUEDC2 takes part in cisplatin-based chemotherapy resistance by regulating p38 MAPK signaling. And CUEDC2 is a promising biomarker and therapeutic target of cisplatin resistance in ovarian serous carcinoma.
The parameters for polarization distortion of spaceborne polarimetric synthetic aperture radar (SAR) have range-dependence (or look-angle-dependence), which requires a polarimetric calibration to be performed at any look-angle. It is a huge endeavor to rely solely on ground experiments to obtain a polarimetric calibration at all look-angles. For SAR with phased array antennas we deduce, based on the model for the general polarimetric system, the model for fine polarization distortion described by the parameters of the radar device under the condition of high polarization isolation. We point out the mechanism that causes both variable and constant polarization distortions, and we deduce the correction algorithms for the two types of polarization distortion. Then we propose a polarimetric calibration scheme combining internal and external calibrations to calibrate the two types of polarization distortions for SAR with phased array antennas. The scheme uses the internal calibration data of the radar and the model of the antenna pattern established before satellite launch to invert the in-orbit antenna patterns to correct for the variable polarization distortion, and it needs only a small amount of calibration equipment to solve for the parameters for constant polarization distortion. The scheme no longer depends on the distributed target and improves the polarization precision of the data. It is applied to the calibration experiment for the data processing of the GaoFen-3 satellite and has achieved good results in applications.
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