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Among recent measures for risk management, value at risk (VaR) has been criticized because it is not coherent and expected shortfall (ES) has been criticized because it is not robust to outliers. Recently, [Math. Oper. Res., 38, 393–417 (2013)] proposed a risk measure called median shortfall (MS) which is distributional robust and easy to implement. In this paper, we propose a more generalized risk measure called quantile shortfall (QS) which includes MS as a special case. QS measures the conditional quantile loss of the tail risk and inherits the merits of MS. We construct an estimator of the QS and establish the asymptotic normality behavior of the estimator. Our simulation shows that the newly proposed measures compare favorably in robustness with other widely used measures such as ES and VaR.

Traditional clutter suppression methods are mainly studied under the condition that the pulse repetition frequency (PRF) of the system is not less than the Nyquist frequency. Whereas in the high-resolution and wide-swath (HRWS) multichannel synthetic aperture radar (SAR) system, a low PRF is used to break through the minimum antenna area constraint. The low PRF case brings new challenges to the traditional clutter suppression methods. In this letter, a subspace projection clutter suppression method is proposed based on the fact that moving targets and the clutter consist in different signal subspaces. This method can be directly applied to the HRWS multichannel SAR system, and it shows better performance compared to the space-time adaptive processing (STAP) when the moving target components cannot be ignored in the clutter covariance matrix calculation. Simulated data and airborne measured data are processed to verify its effectiveness.

The curved trajectory and long synthetic aperture time of medium-Earth-orbit (MEO) synthetic aperture radar (SAR) lead to a 2-D spatial variation in the signals. Traditional methods treat the range and azimuth variations separately and usually suffer from high computational complexities. In this article, we investigate the Doppler rate distribution across a large scene and exploit an optimal imaging coordinate system, in which the MEO SAR signals satisfy the azimuth-shift-invariant property. Thus, the additional processing of the azimuth spatial variation in MEO SAR imaging algorithms can be avoided, and the efficiency of the image formation processor can be obviously improved. The Doppler linearization is used to address the higher-order Doppler parameters to achieve more precise focusing, and at the same time, addresses the azimuth time shift caused by the changes of signal distribution. Finally, processing results of simulated stripmap-mode data with the 2-m resolution are presented to validate the proposed algorithm.

From a historical perspective, it was only in the modern era that the academic profession was favored by the middle and upper classes who came to dominate it. This article shows that, in contempora...

Purpose Antimalarial drug resistance is one of the major challenges in global efforts to control and eliminate malaria. In 2006, sulfadoxine-pyrimethamine (SP) replaced with artemisinin-based combination therapy (ACT) on Bioko Island, Equatorial Guinea, in response to increasing SP resistance, which is associated with mutations in the dihydrofolate reductase (Pfdhfr) and dihydropteroate synthase (Pfdhps) genes. Patients and Methods To evaluate the trend of molecular markers associated with SP resistance on Bioko Island from 2011 to 2017, 179 samples collected during active case detection were analysed by PCR and DNA sequencing. Results Pfdhfr and Pfdhps gene sequences were obtained for 90.5% (162/179) and 77.1% (138/179) of the samples, respectively. For Pfdhfr, 97.5% (158/162), 95.7% (155/162) and 98.1% (159/162) of the samples contained N51I, C59R and S108N mutant alleles, respectively. And Pfdhps S436A, A437G, K540E, A581G, and A613S mutations were observed in 25.4% (35/138), 88.4% (122/138), 5.1% (7/138), 1.4% (2/138), and 7.2% (10/138) of the samples, respectively. Two classes of previously described Pfdhfr-Pfdhps haplotypes associated with SP resistance and their frequencies were identified: partial (IRNI-SGKAA, 59.4%) and full (IRNI-SGEAA, 5.5%) resistance. Although no significant difference was observed in different time periods (p>0.05), our study confirmed a slowly increasing trend of the frequencies of these SP-resistance markers in Bioko parasites over the 7 years investigated. Conclusion The findings reveal the general existence of SP-resistance markers on Bioko Island even after the replacement of SP as a first-line treatment for uncomplicated malaria. Continuous molecular monitoring and additional control efforts in the region are urgently needed.

Background This study was conducted to evaluate and update the current prevalence of and risk factors for chronic kidney disease (CKD) and diabetic kidney disease (DKD) in a central Chinese urban population. Methods From December 2017 to June 2018, a total of 5231 subjects were randomly enrolled from 3 communities in 3 districts of Zhengzhou. CKD was defined as estimated glomerular filtration rate (eGFR) 2 or urinary albumin to creatinine ratio ≥ 30 mg/g (albuminuria). Diabetic subjects with systolic blood pressure > 140 mmHg, albuminuria or an eGFR less than 60 mL/min/1.73 m2 were classified as having DKD. Participants completed a questionnaire assessing lifestyle and relevant medical history, and blood and urine specimens were taken. Serum creatinine, uric acid, total cholesterol, triglycerides, low-density lipoprotein, high-density lipoprotein and urinary albumin were assessed. The age- and sex-adjusted prevalences of CKD and DKD were calculated, and risk factors associated with the presence of reduced eGFR, albuminuria, DKD, severity of albuminuria and progression of reduced renal function were analyzed by binary and ordinal logistic regression. Results The overall adjusted prevalence of CKD was 16.8% (15.8–17.8%) and that of DKD was 3.5% (3.0–4.0%). Decreased renal function was detected in 132 participants (2.9, 95% confidence interval [CI]: 2.5–3.2%), whereas albuminuria was found in 858 participants (14.9, 95% CI: 13.9–15.9%). In all participants with diabetes, the prevalence of reduced eGFR was 6.3% (95% CI = 3.9–8.6%) and that of albuminuria was 45.3% (95% CI = 40.4–50.1%). The overall prevalence of CKD in participants with diabetes was 48.0% (95% CI = 43.1–52.9%). The results of the binary and ordinal logistic regression indicated that the factors independently associated with a higher risk of reduced eGFR and albuminuria were older age, sex, smoking, alcohol consumption, overweight, obesity, diabetes, hypertension, dyslipidemia and hyperuricemia. Conclusions Our study shows the current prevalence of CKD and DKD in residents of Central China. The high prevalence suggests an urgent need to implement interventions to relieve the high burden of CKD and DKD in China.

Elevated brain activation, or hyperexcitability, induces cognitive impairment and confers an increased risk of Alzheimer’s disease (AD). Blocking the overexcitation of the neural network may be a promising new strategy to prevent, halt, and even reverse this condition. Physical exercise has been shown to be an effective cognitive enhancer that reduces the risk of AD in elderly individuals, but the underlying mechanisms are far from being fully understood. We explored whether long-term treadmill exercise attenuates amyloid precursor protein (APP)/presenilin-1 (PS1) mutation-induced aberrant network activity and thus improves cognition by altering the numbers and/or distribution of voltage-gated sodium channels (Nav) in transgenic mice. APP/PS1 mice aged 2, 3.5, 5, 6.5, 8, and 9 months underwent treadmill exercise with different durations or at different stages of AD. The alterations in memory, electroencephalogram (EEG) recordings, and expression levels and distributions of Nav functional members (Nav1.1α, Nav1.2, Nav1.6, and Navβ2) were evaluated. The results revealed that treadmill exercise with 12- and 24-week durations 1) induced significant improvement in novel object recognition (NOR) memory and Morris water maze (MWM) spatial memory; 2) partially reduced abnormal spike activity; and 3) redressed the disturbed cellular distribution of Nav1.1α, aberrant Navβ2 cleavage augmentation, and Nav1.6 upregulation. Additionally, APP/PS1 mice in the 24-week exercise group showed better performance in the NOR task and a large decrease in Nav1.6 expression, which was close to the wild-type level. This study suggests that exercise improves cognition and neural activity by altering the numbers and distribution of hippocampal Nav in APP/PS1 mice. Long-term treadmill exercise, for about 24 weeks, starting in the preclinical stage, is a promising therapeutic strategy for preventing AD and halting its progress.

Due to the limited scenes that synthetic aperture radar (SAR) satellites can detect, the full-track utilization rate is not high. Because of the computing and storage limitation of one satellite, it is difficult to process large amounts of data of spacebome synthetic aperture radars. It is proposed to use a new method of networked satellite data processing for improving the efficiency of data processing. A multi-satellite distributed SAR real-time processing method based on Chirp Scaling (CS) imaging algorithm is studied in this paper, and a distributed data processing system is built with field programmable gate array (FPGA) chips as the kernel. Different from the traditional CS algorithm processing, the system divides data processing into three stages. The computing tasks are reasonably allocated to different data processing units (i.e., satellites) in each stage. The method effectively saves computing and storage resources of satellites, improves the utilization rate of a single satellite, and shortens the data processing time. Gaofen-3 (GF-3) satellite SAR raw data is processed by the system, with the performance of the method verified.

A series of well-defined and uniform pore-structure (WDUPS) TiO2/SiO2 supports with various percentages of rutile TiO2 was developed. Then Fe was introduced into the as-prepared WDUPS supports by incipient wetness impregnation to obtain WDUPS Fe/TiO2/SiO2 catalysts for the Fischer–Tropsch (FT) synthesis. Due to a similar surface OH density in the supports and the same pore structure and Fe loading, the catalytic performance of WDUPS catalysts dominated by percentages of rutile TiO2. Based on the catalytic performance for FT synthesis and the characterization of the H2 temperature-programmed reduction (H2-TPR) and the X-ray photoelectron spectroscopy (XPS), the results suggested that rutile TiO2 acted as a structure promoter in titania-supported iron catalysts and led to an increase in the catalytic activity during FT synthesis. The C5+ selectivity had an increase as the percentage of the rutile phase increased, which was also probably because of rutile TiO2 as a structure promoter for enhancing chain growth.

Background: A novel coronavirus (2019-nCoV) causing an outbreak of pneumonia in Wuhan, Hubei province of China was isolated in January 2020. This study aims to investigate its epidemiologic history, and analyze the clinical characteristics, treatment regimens, and prognosis of patients infected with 2019-nCoV during this outbreak. Methods: Clinical data from 137 2019-nCoV-infected patients admitted to the respiratory departments of the respiratory departments of nine tertiary hospitals in Hubei province from December 30, 2019 to January 24, 2020 were retrospectively collected, including general status, clinical manifestations, laboratory test results, imaging characteristics, and treatment regimens. Results: None of the 137 patients (61 males, 76 females, aged 20–83 years, median age 57 years) had a definite history of exposure to Huanan Seafood Wholesale Market. Major initial symptoms included fever (112/137, 81.8%), coughing (66/137, 48.2%), and muscle pain or fatigue (44/137, 32.1%), with other, less typical initial symptoms observed at low frequency, including heart palpitations, diarrhea, and headache. Nearly 80% of the patients had normal or decreased white blood cell counts, and 72.3% (99/137) had lymphocytopenia. Lung involvement was present in all cases, with most chest computed tomography scans showing lesions in multiple lung lobes, some of which were dense; ground-glass opacity co-existed with consolidation shadows or cord-like shadows. Given the lack of effective drugs, treatment focused on symptomatic and respiratory support. Immunoglobulin G was delivered to some critically ill patients according to their conditions. Systemic corticosteroid treatment did not show significant benefits. Notably, early respiratory support facilitated disease recovery and improved prognosis. The risk of death was primarily associated with age, underlying chronic diseases, and median interval from the appearance of initial symptoms to dyspnea. Conclusions: The majority of patients with 2019-nCoV pneumonia present with fever as the first symptom, and most of them still showed typical manifestations of viral pneumonia on chest imaging. Middle-aged and elderly patients with underlying comorbidities are susceptible to respiratory failure and may have a poorer prognosis.

Resibufogenin (RB) has been used for cancer treatment, but the underlying mechanisms are still unclear. This study aimed to investigate the effects of RB treatment on colorectal cancer (CRC) cells, and to determine the underlying mechanisms. The cell counting kit-8 assay was used to determine cell viability. Cell morphology was observed under light microscopy, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling assay was employed to detect cell apoptosis. Intracellular ferrous iron (Fe2+ ), malondialdehyde (MDA), glutathione (GSH), and reactive oxygen species levels were detected by using commercial iron assay kit, MDA assay kit, GSH assay kit, and 2,7-dichlorodihydrofluorescein diacetate probes, respectively. The protein expressions were determined by Western blot and immunohistochemistry. RB inhibited cell viability in the CRC cell lines (HT29 and SW480) in a dose- and time-dependent manner, and caused cytotoxicity to the normal colonic epithelial cell line (NCM460) at high dose. Similarly, RB induced morphological changes in CRC cells from normal to round shape, and promoted cell death. Of note, RB triggered oxidative stress and ferroptotic cell death in CRC cells, and only ferroptosis inhibitors (deferoxamine and ferrostatin-1), instead of inhibitors for other types of cell death (apoptosis, autophagy, and necroptosis), reversed the inhibitory effects of RB on CRC cell proliferation. Furthermore, glutathione peroxidase 4 (GPX4) was inactivated by RB treatment, and overexpression of GPX4 alleviated RB-induced oxidative cell death in CRC cells. Consistently, the in vivo experiments validated that RB also triggered oxidative stress, and inhibited CRC cells growth and tumorigenicity in mice models. RB can inhibit CRC cells growth and tumorigenesis by triggering ferroptotic cell death in a GPX4 inactivation-dependent manner.

A squinted observation geometry along with long integration time significantly aggravates the range walk and spatial variation of a medium-earth-orbit (MEO) synthetic aperture radar (SAR) signal. Variable pulse repeating frequency (PRF) is recommended to avoid the blockage in echo recording and save storage space. The existing wavenumber algorithms cannot handle the nonlinear and range–azimuth-coupled spatial variation (RACSP) over a large scene. In this paper, we propose a modified Stolt mapping method along with a modified joint time and Doppler resampling (JTDR) for highly squinted MEO SAR data processing. An azimuth timescale transformation is used to deal with the nonlinear spatial variation of the azimuth frequency-modulation (FM) rate. An extended Omega-K is used to linearize the range frequency and achieve range cell migration correction (RCMC). To address the RACSP, the Doppler is linearized in the range-Doppler domain using a range-dependent Doppler scale transformation. The computational complexity and geometry distortion correction (GDC) are also discussed. Simulation results are shown to verify the effectiveness of the developed focusing approaches.

This study objective was to evaluate gender differences in hematological, hormonal and fitness variables among youth swimmers and to explore relationships between erythrocyte indices and aerobic and anaerobic capacity. 137 girls and 171 boys participated in the study and were divided into three groups based on their training experience. Blood samples were obtained to determine red blood cell counts, hemoglobin concentration, hematocrit, and plasma erythropoietin and testosterone levels. VO2max was assessed using a submaximal cycle protocol. 76 girls and 102 boys also undertook a Wingate test to determine their peak anaerobic power. Boys had higher (p < 0.05) means than girls for all hematological variables except for erythropoietin and these variables demonstrated an increase with training in boys. The average VO2max in l∙min-1 and peak anaerobic power in watts were also higher in boys (2.91 ± 0.08 and 547 ± 28, respectively) than girls (2.25 ± 0.07 and 450 ± 26, respectively). Modest but significant (p < 0.05) correlations were found between VO2max and red blood cell counts (r = 0.252), hemoglobin concentration (r = 0.345), or hematocrit (r = 0.345) and between peak anaerobic power and red blood cell counts (r = 0.304), hemoglobin concentration (r = 0.319) or hematocrit (r = 0.351). This study revealed relatively lower yet age- and gender-appropriate hematological, hormonal and fitness indices in youth swimmers. The gender-related differences in erythrocyte indices seem unrelated to erythropoietin and may be explained by the higher testosterone levels seen in boys. Given their correlation to both aerobic and anaerobic capacity, erythrocyte indices may be used as part of talent identification for sports.

This study investigated the physicochemical characteristics and antioxidant activities of cell-bound exopolysaccharides (c-EPS) from Lactobacillus fermentum S1 extracted using either phenol (CFP) or ethylenediaminetetraacetic acid (CFE). The extraction products, CFP and CFE, were homogeneous polysaccharides with molecular weights of 2.89 × 105 and 2.44 × 105 Da, respectively. Both CFP and CFE were composed of five kinds of monosaccharides. They had a main chain of β-D-Glcp-(1→2), α-L-Rhap-(1→2), β-D-Galp-(1→3), α-D-Glcp-(1→3), α-D-Galp-(1→3) and β-L-Rhap-(1→3,4) residues, and a tail of α-D-Manp-(1→) residue, but with different molar ratios. Trace amounts of D-Galp-(1→) and L-Araf-(1→2,5) residues were randomly distributed in the sugar chains. Although both CFP and CFE were in triple-helical conformation, they differed from each other in relation to surface morphology and thermal properties. The two c-EPS had different performances in radical scavenging and ferric reducing antioxidant power assays in vitro. The antioxidant capacity of both c-EPS extracts was confirmed in vivo using Caenorhabditis elegans, whose total antioxidant capacity and total superoxide dismutase activity increased after c-EPS treatment. Overall, the extraction method significantly affected the structure and biological activity of c-EPS. Moreover, the potent antioxidant activities of CFP and CFE support their use as natural antioxidants in dietary supplements or food additives.

Cerebral syphilitic gumma is a rarely reported disease of the central nervous system. Magnetic resonance imaging (MRI) is an important diagnostic method for syphilitic gumma. The present study aimed to describe and characterize neuroimaging results from 6 patients with pathologically diagnosed cerebral syphilitic gumma. The 6 patients (age, 32-61 years) underwent brain CT and MRI, with 1 patient also undergoing whole-body 2-deoxy-2-(fluorine-18)fluoro-D-glucose-positron emission tomography/CT (18F-FDG PET/CT). Non-enhanced CT, conventional T1 weighted imaging (T1WI) and T2WI, diffusion weighted imaging (DWI) and gadolinium-enhanced T1WI images were acquired for all patients. The CT and MRI scans were retrospectively reviewed by two experienced radiologists for consensus on the location, number, size, T1WI, T2WI and DWI signal intensity characteristics, extent of vasogenic oedema, and enhancement patterns. In total, the 6 patients exhibited 10 lesions, nine of which were located in the cerebral hemisphere, primarily in the grey matter. The remaining lesion was located in the fourth ventricle, leading to mild-to-moderate hydrocephalus. The diameters of the identified 10 lesions ranged from 0.9-6.5 cm, with a mean diameter of 3.9 cm. The main feature observed in CT was low density and in MRI the features were T1WI and DWI hypointensity and T2WI hyperintensity. A single case exhibited syphilis gumma with massive haemorrhage. Ring-like or strip-like signs (n=5), accompanied by the dural tail sign (n=2) and homogeneous enhancement (n=1), were noted on T1WI with gadolinium. The 18F-FDG PET/CT performed in one patient of a cerebral syphilis gumma revealed low uptake and metabolism. The present study indicated that gadolinium-enhanced MRI combined with 18F-FDG PET/CT and laboratory examinations are helpful in distinguishing cerebral syphilitic gumma from brain tumors and infectious diseases, therefore avoiding unnecessary surgery.

Rice (Oryza sativa L.) is one of the most important crops in the world, and grain size is a major component determining rice yield. Recent studies identified a number of grain size regulators, which are involved in the phytohormone signaling, G protein signaling, mitogen-activated protein kinase signaling pathway, ubiquitin-proteasome pathway, or transcriptional regulation. In previous study, we cloned qGL3/OsPPKL1 encoding a rice protein phosphatase that negatively modulates brassinosteroid (BR) signaling and grain length. Here, to further explore qGL3-mediated BR signaling network, we performed phosphoproteomic screenings using two pairs of rice materials: the indica rice cultivar 9311 and its near-isogenic line NILqgl3 and the japonica rice cultivar Dongjin and its qGL3 knockout mutant m-qgl3. Together with qGL3-interacting proteins, we constructed the qGL3-mediated network, which reveals the relationships between BR signaling and other critical signaling pathways. Transgenic plants of these network components showed BR-related alterations in plant architecture. From this network, we validated a qGL3-interacting protein, O. sativa VERNALIZATION INSENSITIVE3-LIKE1 (OsVIL1), and demonstrated that qGL3 dephosphorylates OsVIL1 to modulate BR signaling. The qGL3-dependent network uncovered in this study increases our understanding of BR signaling and provides a profound foundation for addressing how BR modulates plant architecture in rice.

Focusing on the characteristics of public participation and large group decision making of major livelihood projects, this paper proposes a multi-agent linguistic-style large group decision-making method with the consideration of public expectations. Firstly, based on the discrimination degree of evaluating information, the comprehensive weight of each attribute is calculated with the principle of maximum entropy. Secondly, the expert preference information for different alternatives is clustered and several aggregations are formed. Thirdly, the preference conflict level of experts' group for each alternative is calculated, and a conflict-oriented experts' aggregation weight optimization model is constructed to ensure the effectiveness of conflict resolution. Fourthly, the public group's satisfaction is determined with the expectation distribution of public’s and the expert group's preference, so as to obtain the sorting result of the decision alternatives. Finally, the effectiveness and applicability of the proposed method are verified by method comparison.

Cervical cancer, which is significantly associated with high-risk human papillomavirus (HPV) infection, currently ranks the fourth most common cancer among women worldwide. Previous literature reported that the elevated expression of G6PD was significantly correlated with the occurrence and deterioration of human cervical cancer, especially with the cervical cancer with HPV16 and HPV18 infection. In this study, we verified that G6PD expression has a strong positive correlation with HPV16 E6 levels in cervical cancer tissues and cells. In addition, regulating the expression of HPV16 E6 significantly affected the proliferation, apoptosis, migration, and invasion in the cervical cancer HeLa cells, as well as the transcript and protein levels of G6PD. The luciferase reporter assay and ChIP assay proved that HPV16 E6 stimulated the transcription of G6PD mRNA and subsequently enhanced the expression of G6PD through directly binding to the specific sites in the promoter of G6PD. Our findings reveal that HPV16 E6 is a novel regulatory factor of G6PD. Furthermore, by regulating the expression of G6PD, HPV16 E6 might promote the proliferation and migration potential, and inhibit apoptosis of cervical cancer cells, which ultimately contributed to the progression and metastasis of cervical cancer.

In a short observation time, after the range alignment and phase adjustment, the motion of a target can be approximated as a uniform rotation. The radar observing process can be simply described as multiplying an observation matrix on the ISAR image, which can be thought of as a linear system. It is known that the longer observation time is, the higher cross-range resolution is. In order to deal with the conflict between short observation time and high cross-range resolution, we introduce Kalman filtering (KF) into the ISAR imaging and propose a novel method to reconstruct a high-resolution image with short time observed data. As KF has excellent reconstruction performance, it leads to a good application in ISAR image reconstruction. At each observation aperture, the reconstructed image denotes the state vector in KF at the aperture time. It is corrected by a two-step KF process: prediction and update. As iteration continues, the state vector is gradually corrected to a well-focused high-resolution image. Thus, the proposed method can obtain a high-resolution image in a short observation time. Both simulated and real data are applied to demonstrate the performance of the proposed method.

Heterologous expression of eukaryotic gene clusters in yeast has been widely used for producing high-value chemicals and bioactive secondary metabolites. However, eukaryotic transcription cis-elements are still undercharacterized, and the cross-species expression mechanism remains poorly understood. Here we used the whole expression unit (including original promoter, terminator, and open reading frame with introns) of orotidine 5′-monophosphate decarboxylases from 14 Penicillium species as a showcase, and analyzed their cross-species expression in Saccharomyces cerevisiae. We found that pyrG promoters from the Penicillium species could drive URA3 expression in yeast, and that inefficient cross-species splicing of Penicillium introns might result in weak cross-species expression. Thus, this study demonstrates cross-species expression from Penicillium to yeast, and sheds light on the opportunities and challenges of cross-species expression of fungi expression units and gene clusters in yeast without refactoring for novel natural product discovery.

Due to the constraint of minimum antenna area, azimuth ambiguity resolving is a challenging task in the ship focusing for single-channel synthetic aperture radar (SAR) mounted on high-speed maneuvering platforms. In order to accommodate the issues, a ship focusing algorithm based on azimuth ambiguity resolving is proposed in this paper. For ship SAR imaging with small-aperture data, the energies of different targets are separated in Doppler domain with different Doppler ambiguity numbers. Thus, the Doppler ambiguity number of a single target can be estimated by residual envelope inclination. Then, the target can be accurately focused and located at the correct position by the known Doppler ambiguity number. After the operation of each target is completed, the focusing SAR image of the whole scene can be obtained. Finally, simulation results are presented to validate the proposed algorithm.

The existing microwave remote sensors for ocean wave observation, such as SAR and spectrometer, have their respective specialties through different measuring mechanisms. However, every individual sensor shows obvious limitations when considering advanced wide-swath complete-elements ocean wave observation. This paper proposes an integrated microwave remote sensor for double-mode ocean wave observation, and designs the main system parameters and the joint time sequence. The double-mode integrated microwave remote sensor adopts a digital array antenna, but functions as a spectrometer and a SAR simultaneously through multiple beam forming technology. The proposed double-mode integrated microwave remote sensor not only realizes simultaneous, wide-swath, relatively complete-elements, and high-accuracy observation, but also reduces the cost, and compared to traditional single satellite multi-payload systems, it is more probable.

When airborne radar platforms have a hypersonic speed, the Doppler bandwidth will be several hundred times of that from the low speed platforms. There are contradictions between pulse repeat frequency (PRF), Doppler ambiguity and range swath during the system parameters design. Azimuth multichannel technique is applied to make the PRF lower and can get a wide range swath. The equivalent phase center (EPC) under high squint (HS) mode is calculated. Then the Doppler spectrum is reconstructed by spatial filtering method with azimuth dependent channel compensation.

Moving ship refocusing is challenging because the target motion parameters are unknown. Moreover, moving ships in squint synthetic aperture radar (SAR) images obtained by the back-projection (BP) algorithm usually suffer from geometric deformation and spectrum winding. Therefore, a spectrum-orthogonalization algorithm that refocuses moving ships in squint SAR images is presented. First, “squint minimization” is introduced to correct the spectrum by two spectrum compression functions: one to align the spectrum centers and another to translate the inclined spectrum into orthogonalized form. Then, the precise analytic function of the two-dimensional (2D) wavenumber spectrum is derived to obtain the phase error. Finally, motion compensation is performed in the two-dimensional wavenumber domain after the motion parameter is estimated by maximizing the image sharpness. This method has low computational complexity because it lacks interpolation and can be implemented by the inverse fast Fourier translation (IFFT) and fast Fourier translation (FFT). Processing results of simulation experiments and the GaoFen-3 squint SAR data validate the effectiveness of this method.