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OBJECTIVE: The objective of this study was to compare the outcomes of endoscopic cartilage underlay myringoplasty(CNM) with or without balloon Eustachian tuboplasty (BET) for the treatment of chronic perforation with Eustachian tube dysfunction (ETD). MATERIALS AND METHODS: A total of 50 ears diagnosed with chronic perforation and ETD were randomly divided into receiving alone CNM and CNM + BET. During the 12 months follow-up, the Eustachian tube score (ETS), Eustachian Tube Dysfunction Questionnaire-7 (ETDQ-7), ET inflammation scale, hearing results and graft success rate of the patients were recorded and analyzed. RESULTS: The improvement in the ETDQ-7 score was 6.23 ± 2.51 in the CNM + BET group, which was significantly higher than that in the CNM group (4.22 ± 3.85, P < 0.01) at postoperative 3 months, however, no significant between-group difference was found at post-12 months.The graft success rate was 88.0 % in the CNM group and 92.0 % in the CNM + BET group at postoperative 3 months (P > 0.05). Also, no significant difference was found among two groups (84.0 % vs 88.0 %, P > 0.05).The ABG improvement was 13.16 ± 3.19 dB in the CNM + BET group and 9.74 ± 2.56 dB in the CNM group, with a statistically significant between-group difference (P < 0.01)at postoperative 3 months. However, no significant between-group difference was found at postoperative 12 months. During followup process, neither complications nor patulous symptoms were noted. No patients developted atelectasis or otitis media with effusion. However, myringitis was seen in 8 % patients in the CNM group and 12 % patients in the CNM + BET group. CONCLUSIONS: Although BET combined with endoscopic cartilage myringoplasty had better short-term improvement of hearing and ETDQ-7 scores compared with endoscopic cartilage myringoplasty for the treatment of chronic large perforation with ETD, the long-term outcomes was not satisfactory. Also, BET did not improve the 3-and 12 months graft success rate.
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As climate change intensifies, attention to the issue of carbon emission reduction has gradually increased. This research constructs a complete set of indicators of carbon reduction attention and financial market stress and applies the quantile VAR method to calculate the volatility spillover between carbon reduction attention and financial market stress. We conclude with the following. Firstly, a relatively close volatility spillover association exists between carbon reduction attention and financial market stress. In the research system, carbon reduction attention mainly assumes the role of information receiver. Additionally, when examining the spillover status in different quantiles, the total spillover level shows an irregular "bowl" structure, while the net spillover level of each variable has different shapes. Secondly, the dynamic spillover level in the extreme quantile condition maintains a connectivity range of 60-80%, significantly higher than that of the median condition. Finally, this study finds two sets of significant complementary spillovers within the system, namely, "carbon reduction attention - crude oil market stress" and "stock market stress - real estate market stress", which provide investors with an opportunity to explore the potential of the carbon reduction attention and real estate market stress in the future.
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Carbono , Petróleo , Mudança ClimáticaRESUMO
Hypertrophic/dilated cardiomyopathy, often a prequel to heart failure, is accompanied by maladaptive transcriptional changes that contribute to arrythmias and contractile misfunction. Transgenic mice constitutively expressing high levels of calcineurin are known to develop extreme heart hypertrophy, which progresses to dilated cardiomyopathy, and to die several weeks after birth. Here, we characterized aberrant transcriptional and epigenetic pathways in this mouse model and established a pharmacological approach to treat established cardiomyopathy. We found that H3K4me3 (trimethyl histone 3 lysine 4) and H3K9me3 (trimethyl histone 3 lysine 9) Jumonji histone demethylases are markedly increased at the protein level and show enhanced enzymatic activity in diseased hearts. These epigenetic regulators continued to increase with time, further affecting cardiac gene expression. Our findings parallel the lower H3K4me3 and H3K9me3 levels seen in human patients. Inhibition of Jumonji demethylase activities in vivo results in lower histone demethylase enzymatic function in the heart and higher histone methylation levels and leads to partial reduction of heart size, reversal of maladaptive transcriptional programs, improved heart function, and prolonged survival. At the molecular level, target genes of transcription factor myocyte enhancer factor 2 are specifically regulated in response to pharmacological or genetic inhibition of Jumonji demethylases. Similar transcriptional reversal of disease-associated genes is seen in a second disease model based on cardiac mechanical overload. Our findings validate pharmacological inhibitors of Jumonji demethylases as potential therapeutics for the treatment of cardiomyopathies across disease models and provide evidence of the reversal of maladaptive transcriptional reprogramming leading to partial restoration of cardiac function. In addition, this study defines pathways of therapeutic resistance upregulated with disease progression.
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Cardiomiopatia Dilatada , Inibidores Enzimáticos , Histona Desmetilases com o Domínio Jumonji , Animais , Cardiomiopatia Dilatada/tratamento farmacológico , Cardiomiopatia Dilatada/genética , Inibidores Enzimáticos/farmacologia , Histona Desmetilases/genética , Histona Desmetilases/metabolismo , Histonas/genética , Histonas/metabolismo , Humanos , Histona Desmetilases com o Domínio Jumonji/antagonistas & inibidores , Histona Desmetilases com o Domínio Jumonji/metabolismo , Lisina/metabolismo , Camundongos , Bibliotecas de Moléculas Pequenas/farmacologiaRESUMO
[Figure: see text].
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Infarto do Miocárdio/metabolismo , Miofibroblastos/metabolismo , Pirofosfatases/metabolismo , Animais , Células Cultivadas , Fibrose , Células HEK293 , Humanos , Alvo Mecanístico do Complexo 1 de Rapamicina/metabolismo , Camundongos , Camundongos Endogâmicos C57BL , Infarto do Miocárdio/patologia , Miocárdio/metabolismo , Miocárdio/patologia , Miofibroblastos/patologia , Pirofosfatases/genéticaRESUMO
Interspecies sensitivity to the same chemical can be several orders of magnitude different. Quantifying toxicologically internal levels and toxicokinetic (TK) parameters is critical in elucidating the interspecies sensitivity. Herein, a two-compartmental TK model was constructed to characterize the uptake, distribution, and elimination kinetics toward interspecies sensitivity to an insecticide, imidacloprid. Imidacloprid exhibited the highest lethality to the insect Chironomus dilutus, followed by Lumbriculus variegatus, Hyalella azteca, and Daphnia magna. Interspecies sensitivity of imidacloprid to these invertebrates varied by â¼1000 folds based on water concentrations (LC50). Remarkably, the sensitivity variation decreased to â¼50 folds based on the internal residues (LR50), highlighting the critical role of TK in interspecies sensitivity. A one-compartmental TK model failed to simulate the bioaccumulation of imidacloprid in these invertebrates except for D. magna. Instead, a two-compartmental model successfully simulated the slow elimination of imidacloprid in the remaining three species by internally distinguishing the highly dynamic (C1) and toxicologically available (C2) fractions. We further showed that the species sensitivity of the invertebrates to imidacloprid was significantly related to C2, demonstrating that C2 was toxicologically available and responsible for the toxicity of imidacloprid. This mechanistic-based model bridged the internal distribution of organic contaminants in small invertebrates and the associated toxic potency.
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Inseticidas , Poluentes Químicos da Água , Animais , Modelos Epidemiológicos , Toxicocinética , Invertebrados , Neonicotinoides/toxicidade , Inseticidas/toxicidade , Nitrocompostos/toxicidade , Poluentes Químicos da Água/toxicidadeRESUMO
The enrichment and adaptation of hyper-thermal compost-derived thermophilic inoculum by repeated batch cultivation (RBC) was conducted by investigating bacterial community. The effects of recycling hyper-thermal inoculum by RBC into co-composting were investigated through evaluating the influences of temperature, pH, moisture, C/N ratio, transformation of nitrogen, composting maturity, humification levels and scanning electron microscopy (SEM). The results showed that RBC enriched the thermophilic bacterial community and nitrogen fixation bacteria of the compost-derived thermophilic inoculum. Simultaneously, recycling the inoculum into co-composting increased the temperature, nitrate nitrogen (NO3--N) and Germination index (GI), and improved the transformation of nitrogen and humification levels. Conclusively, recycling hyper-thermal inoculum by RBC into co-composting can improve the degradation process.
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Compostagem , Solo , Animais , Aves Domésticas , Esterco , Esgotos/microbiologia , Gado , Nitrogênio/análise , BactériasRESUMO
BACKGROUND: China's socioeconomic and population structures have evolved markedly during the past few decades, and consequently, monitoring the prevalence of Parkinson's disease (PD) is crucial. OBJECTIVE: This study aimed to investigate the prevalence of PD within Chinese communities, particularly in older people. METHODS: A nationwide study of 24,117 participants, aged 60 years or older, was carried out in 2015 using multistage clustered sampling. All participants were initially screened using a nine-item questionnaire, from which those suspected of having PD were examined by neurologists and a diagnosis was given, according to the 2015 Movement Disorder Society Clinical Diagnostic Criteria. RESULTS: The prevalence of PD was 1.37% (95% confidence interval 1.02%-1.73%) in people aged over 60 years. Thus, the estimated total number of people in China with PD could be as high as 3.62 million. CONCLUSIONS: Although the PD population prevalence percentage did not change significantly, the total number of PD sufferers has increased with the increased population, which poses a significant challenge in a rapidly aging population. © 2021 International Parkinson and Movement Disorder Society.
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Doença de Parkinson , Idoso , Envelhecimento , China/epidemiologia , Humanos , Pessoa de Meia-Idade , Doença de Parkinson/diagnóstico , Doença de Parkinson/epidemiologia , Prevalência , Inquéritos e QuestionáriosRESUMO
PARP1 inhibitors (PARPi) are known to kill tumor cells via two mechanisms (PARP1 catalytic inhibition and PARP1 trapping). The relative contribution of these two pathways in mediating the cytotoxicity of PARPi, however, is not well understood. Here we designed a series of small molecule PARP degraders. Treatment with one such compound iRucaparib-AP6 results in highly efficient and specific PARP1 degradation. iRucaparib-AP6 blocks the enzymatic activity of PARP1 in vitro, and PARP1-mediated poly-ADP-ribosylation signaling in intact cells. This strategy mimics PARP1 genetic depletion, which enables the pharmacological decoupling of PARP1 inhibition from PARP1 trapping. Finally, by depleting PARP1, iRucaparib-AP6 protects muscle cells and primary cardiomyocytes from DNA-damage-induced energy crisis and cell death. In summary, these compounds represent 'non-trapping' PARP1 degraders that block both the catalytic activity and scaffolding effects of PARP1, providing an ideal approach for the amelioration of the various pathological conditions caused by PARP1 hyperactivation.
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Poli(ADP-Ribose) Polimerase-1/metabolismo , Animais , Humanos , Camundongos , Poli(ADP-Ribose) Polimerase-1/antagonistas & inibidores , ProteóliseRESUMO
Species sensitivity to neonicotinoids has been shown to be highly variable among aquatic invertebrates. Toxicokinetic and toxicodynamic (TKTD) models were constructed to mechanistically elucidate the susceptibility of Daphnia magna to imidacloprid. D. magna was highly tolerant to single short-term exposure to imidacloprid (96-h LC50 of 8.47 µg/mL), but delayed and carry-over toxicity occurred under repeated pulse exposures. Kinetic distribution of imidacloprid between exoskeleton and soft tissues of D. magna was evaluated using a newly developed method. Approximately 84% imidacloprid was distributed to soft tissues but was rapidly depurated from the tissue (t1/2 of 1.2 h), resulting in low bioaccumulation and high tolerance. TKTD modeling also successfully simulated the survival of D. magna after pulsed exposures. The calculated recovery time was 45 d, indicating significant delayed and carry-over toxicity of the insecticide. While complete elimination of imidacloprid only took about 5 h (TK), slow damage recovery (45 d) caused slow organism recovery (TD). Consequently, although D. magna was tolerant to imidacloprid due to fast depuration from soft tissue, long damage recovery time significantly enhanced the toxicity under repeated pulse exposures. Our study highlights the necessity of integrating delayed and carry-over toxicity quantification in assessing the risk of neonicotinoids to aquatic invertebrates.
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Inseticidas , Poluentes Químicos da Água , Animais , Daphnia , Inseticidas/toxicidade , Neonicotinoides/toxicidade , Nitrocompostos , Toxicocinética , Poluentes Químicos da Água/toxicidadeRESUMO
Alternative splicing is emerging as an oncogenic mechanism. In prostate cancer, generation of constitutively active forms of androgen receptor (AR) variants including AR-V7 plays an important role in progression of castration-resistant prostate cancer (CRPC). AR-V7 is generated by alternative splicing that results in inclusion of cryptic exon CE3 and translation of truncated AR protein that lacks the ligand binding domain. Whether AR-V7 can be a driver for CRPC remains controversial as the oncogenic mechanism of AR-V7 activation remains elusive. Here, we found that KDM4B promotes AR-V7 and identified a novel regulatory mechanism. KDM4B is phosphorylated by protein kinase A under conditions that promote castration-resistance, eliciting its binding to the splicing factor SF3B3. KDM4B binds RNA specifically near the 5'-CE3, upregulates the chromatin accessibility, and couples the spliceosome to the chromatin. Our data suggest that KDM4B can function as a signal responsive trans-acting splicing factor and scaffold that recruits and stabilizes the spliceosome near the alternative exon, thus promoting its inclusion. Genome-wide profiling of KDM4B-regulated genes also identified additional alternative splicing events implicated in tumorigenesis. Our study defines KDM4B-regulated alternative splicing as a pivotal mechanism for generating AR-V7 and a contributing factor for CRPC, providing insight for mechanistic targeting of CRPC.
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Processamento Alternativo/genética , Regulação Neoplásica da Expressão Gênica/genética , Histona Desmetilases com o Domínio Jumonji/genética , Neoplasias de Próstata Resistentes à Castração/genética , Receptores Androgênicos/genética , Carcinogênese/genética , Linhagem Celular Tumoral , Cromatina/metabolismo , Células HEK293 , Humanos , Masculino , Isoformas de Proteínas/genética , Receptores Androgênicos/metabolismo , Spliceossomos/genéticaRESUMO
BACKGROUND Our research explored if Interleukin-6 (IL-6) variants held substantial connection to congenital heart disease (CHD) susceptibility among Chinese Han children. MATERIAL AND METHODS A total of 102 CHD children were recruited as the case group while 98 healthy persons were recruited as the control group. We used polymerase chain reaction restriction fragment length polymorphism (PCR-RFLP) completed genotyping for IL-6 variants rs1800795 and rs1800796. The Hardy-Weinberg equilibrium (HWE) among controls was tested using χ² analysis. Genotype and allele frequencies for variants were compared between groups. Odds ratio (OR) accompanied by 95% confidence interval (CI) reflected the potential link of IL-6 variants to CHD occurrence. RESULTS A remarkable increased trend of rs1800795 CC genotype and C allele was detected in the CHD patient group (P<0.05). Individuals carrying rs1800795 CC genotype showed higher risk for CHD (OR=3.763, 95% CI=1.162 - 12.190). In addition, rs1800795 C allele could increase CHD incidence (OR=1.766, 95% CI=1.101 - 2.832). No significant differences were detected in IL-6 gene rs1800796 polymorphism in both genotype and allele distributions between the case group and the control group (P>0.05). These associations had no significant alteration after the adjustment of age, gender, maternal smoking history, and maternal history of diabetes. CONCLUSIONS IL-6 variant rs1800795 exhibited a close relation to CHD susceptibility among Chinese Han people while the mutant C allele promoted CHD incidence. But rs1800796 variant showed no such influence.
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Cardiopatias Congênitas/genética , Interleucina-6/genética , Alelos , Povo Asiático/genética , Estudos de Casos e Controles , Criança , Pré-Escolar , China/epidemiologia , Etnicidade/genética , Feminino , Frequência do Gene/genética , Predisposição Genética para Doença/genética , Genótipo , Cardiopatias Congênitas/metabolismo , Humanos , Incidência , Lactente , Recém-Nascido , Interleucina-6/metabolismo , Masculino , Razão de Chances , Polimorfismo de Nucleotídeo Único/genética , Fatores de RiscoRESUMO
BACKGROUND: Evidence on historical trends extracted embedded in recent data can advance our understanding of the epidemiology of breast cancer for Chinese women. China is a country with significant political, socioeconomic, and cultural events since the 1900s; however, no such studies are reported in the literature. METHODS: Age-specific mortality rates of breast cancer during 1990-2015 in China were analyzed using APC modeling (age-period-cohort modeling) method. Net effect from birth cohort was derived to measure cancer mortality risk during 1906-1990 when no mortality data were collected, and net effect from time period was derived to measure cancer mortality risk during 1990-2015 when data were collected. Model parameters were estimated using intrinsic estimator, a novel method to handle collinearity. The estimated effects were numerical differentiated to enhance presentations of time/age trend. RESULTS: Breast cancer mortality rate per 100,000 women increased from 6.83 in 1990 to 12.07 in 2015. After controlling for age and period, the risk of breast cancer mortality declined from 0.626 in 1906-10 to - 1.752 in 1991-95 (RR = 0.09). The decline consisted of 3 phases, a gradual phase during 1906-1940, a moderate phase with some fluctuations during 1941-1970, and a rapid phase with large fluctuations during 1971-1995. After controlling for age and cohort, the risk of breast cancer mortality increased from - 0.141 in 1990 to 0.258 in 2015 (RR = 1.49) with an acceleration after 2005. The time trends revealed by both the cohort effect and the period effect were in consistency with the significant political and socioeconomic events in China since the 1900s. CONCLUSIONS: With recent mortality data in 1990-2015, we detected the risk of breast cancer mortality for Chinese women over a long period from 1906 to 2015. The risk declined more than 90% from the highest level in 1906-10 to the lowest in 1990-95, followed by an increase of 49% from 1990 to 2015. Findings of this study connected historical evidence with recent data, supporting further research to exam the relationship between development and risk of breast cancer for medical and health decision-making at the population level and prevention and treatment at the individual level.
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Neoplasias da Mama/história , Neoplasias da Mama/mortalidade , Adulto , Idoso , Idoso de 80 Anos ou mais , China/epidemiologia , Efeito de Coortes , Estudos de Coortes , Feminino , História do Século XX , História do Século XXI , Humanos , Pessoa de Meia-Idade , Modelos Estatísticos , Mortalidade/história , Mortalidade/tendências , Determinantes Sociais da Saúde , Adulto JovemRESUMO
Mainly focusing on the demand for a novel resonator optic gyro based on a hollow-core photonic-crystal fiber (HC-RFOG), we achieve a multi-frequency lasers generation with low relative phase noise via an acousto-optic modulation of light from a single laser diode. We design a homologous heterodyne digital optical phase-locked loop (HHD-OPLL), based on which we realize the low-noise multi-frequency lasers (LNMFLs) with an intermediate frequency difference. The noise between the lasers with a 20 MHz difference is 0.036 Hz, within the bandwidth of 10 Hz, in a tuning range of 120 kHz, approximately 40 dB lower than that produced without the HHD-OPLL. Finally, based on the LNMFLs, an HC-RFOG is realized and a bias stability of 5.8 °/h is successfully demonstrated.
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BACKGROUND: Cardiac dysfunction is a major component of sepsis-induced multiorgan failure in critical care units. Changes in cardiac autophagy and its role during sepsis pathogenesis have not been clearly defined. Targeted autophagy-based therapeutic approaches for sepsis are not yet developed. METHODS: Beclin-1-dependent autophagy in the heart during sepsis and the potential therapeutic benefit of targeting this pathway were investigated in a mouse model of lipopolysaccharide (LPS)-induced sepsis. RESULTS: LPS induced a dose-dependent increase in autophagy at low doses, followed by a decline that was in conjunction with mammalian target of rapamycin activation at high doses. Cardiac-specific overexpression of Beclin-1 promoted autophagy, suppressed mammalian target of rapamycin signaling, improved cardiac function, and alleviated inflammation and fibrosis after LPS challenge. Haplosufficiency for beclin 1 resulted in opposite effects. Beclin-1 also protected mitochondria, reduced the release of mitochondrial danger-associated molecular patterns, and promoted mitophagy via PTEN-induced putative kinase 1-Parkin but not adaptor proteins in response to LPS. Injection of a cell-permeable Tat-Beclin-1 peptide to activate autophagy improved cardiac function, attenuated inflammation, and rescued the phenotypes caused by beclin 1 deficiency in LPS-challenged mice. CONCLUSIONS: These results suggest that Beclin-1 protects the heart during sepsis and that the targeted induction of Beclin-1 signaling may have important therapeutic potential.
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Autofagia , Proteína Beclina-1/metabolismo , Sepse/patologia , Animais , Autofagia/efeitos dos fármacos , Modelos Animais de Doenças , Lipopolissacarídeos/toxicidade , Masculino , Camundongos , Camundongos Endogâmicos C57BL , Camundongos Knockout , Proteínas Associadas aos Microtúbulos/metabolismo , Mitocôndrias/efeitos dos fármacos , Mitocôndrias/genética , Mitocôndrias/metabolismo , Miocárdio/metabolismo , Miocárdio/patologia , PTEN Fosfo-Hidrolase/metabolismo , Sepse/etiologia , Proteína Sequestossoma-1/metabolismo , Transdução de Sinais/efeitos dos fármacos , Serina-Treonina Quinases TOR/metabolismo , Ubiquitina-Proteína Ligases/metabolismoRESUMO
Cardiac autophagy inhibitory factor (CAIF) is a novel lncRNA with protective effects on myocardial infarction. We explored the involvement of CAIF in end-stage cardiomyopathy. Patients with end-stage cardiomyopathy and healthy volunteers were included in this study. Myocardial tissues and serum were collected. CAIF was detected by RT-qPCR. ROC curve was used for diagnostic analysis. Prognostic value of CAIF expression for end-stage cardiomyopathy was evaluated by survival curve analysis. Correlations between CAIF expression and clinicopathological data of patients with end-stage cardiomyopathy were analysed by chi-square test. Downregulated CAIF was observed in end-stage cardiomyopathy patients than in healthy controls. CAIF expression distinguished end-stage cardiomyopathy patients from healthy controls and predict the survival of patients. LncRNA CAIF was downregulated in end-stage cardiomyopathy and may serve as a promising prognostic and diagnostic marker for this disease.
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Cardiomiopatias/diagnóstico , RNA Longo não Codificante/metabolismo , Autofagia/efeitos dos fármacos , Biomarcadores/análise , Cardiomiopatias/genética , Cardiomiopatias/patologia , Estudos de Casos e Controles , Humanos , Prognóstico , RNA Longo não Codificante/análise , RNA Longo não Codificante/farmacologiaRESUMO
Polarimetric SAR (PolSAR) scattering characteristics of imagery are always obtained from the second order moments estimation of multi-polarization data, that is, the estimation of covariance or coherency matrices. Due to the extra-paths that signal reflected from separate scatterers within the resolution cell has to travel, speckle noise always exists in SAR images and has a severe impact on the scattering performance, especially on single look complex images. In order to achieve high accuracy in estimating covariance or coherency matrices, three aspects are taken into consideration: (1) the edges and texture of the scene are distinct after speckle filtering; (2) the statistical characteristic should be similar to the object pixel; and (3) the polarimetric scattering signature should be preserved, in addition to speckle reduction. In this paper, a joint restriction principle is proposed to meet the requirement. Three different restriction principles are introduced to the processing of speckle filtering. First, a new template, which is more suitable for the point or line targets, is designed to ensure the morphological consistency. Then, the extent sigma filter is used to restrict the pixels in the template aforementioned to have an identical statistic characteristic. At last, a polarimetric similarity factor is applied to the same pixels above, to guarantee the similar polarimetric features amongst the optional pixels. This processing procedure is named as speckle filtering with joint restriction principle and the approach is applied to GF-3 polarimetric SAR data acquired in San Francisco, CA, USA. Its effectiveness of keeping the image sharpness and preserving the scattering mechanism as well as speckle reduction is validated by the comparison with boxcar filters and refined Lee filter.
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For the conventional FDA-MIMO (frequency diversity array multiple-input-multiple-output) Radar with uniform frequency offset and uniform linear array, the DOFs (degrees of freedom) of the adaptive beamformer are limited by the number of elements. A better performance-for example, a better suppression for strong interferences and a more desirable trade-off between the main lobe and side lobe-can be achieved with a greater number of DOFs. In order to obtain larger DOFs, this paper researches the signal model of the FDA-MIMO Radar with nested frequency offset and nested array, then proposes an improved adaptive beamforming method that uses the augmented matrix instead of the covariance matrix to calculate the optimum weight vectors and can be used to improve the output performances of FDA-MIMO Radar with the same element number or reduce the element number while maintain the approximate output performances such as the received beampattern, the main lobe width, side lobe depths and the output SINR (signal-to-interference-noise ratio). The effectiveness of the proposed scheme is verified by simulations.
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The rapid and accurate detection of urban water is critical for urban management, river detection, and flood disaster assessment. This study is devoted to detecting water by GaoFen-3 (GF-3) Synthetic Aperture Radar (SAR) images with high spatial resolution. There have been no effective solutions that discriminate water and building shadows using a single SAR image in previous research. Inspired by the principle that every shadow has a corresponding building nearby, a new method is proposed in this study, whereby building shadows are removed depending on the correspondence of buildings and their shadows. The proposed method is demonstrated effective and efficient by experimental results on six GF-3 SAR images. The Receiver Operating Characteristic (ROC) curves of the water detection results indicate that the proposed method increases the Probability of Detection (PD) to 98.36% and decreases the Probability of False Alarm (PFA) to 1.91% compared with the thresholding method, where, at the same PFA level, the maximum PD of the thresholding method is 72.62% in all testing samples. The proposed method is capable of removing building shadows and detecting water with high precision in urban areas, which presents the great potential of high-spatial-resolution GF-3 images in terms of water resource management.
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The paper proposes a new method for measuring the azimuth pointing of spaceborne synthetic aperture radar (SAR) antenna beams based on the ground receiver, which can receive and record complex sampling data of the pulse signals transmitted from the spaceborne SAR. The center of the antenna pattern is extracted from the complex sampling data amplitude envelope to obtain the time when the beam main lobe center irradiates the ground receiver, and the range migration information is extracted from the complex sampling data to obtain the time when the satellite is over the top of the ground receiver. The results of Chinese civilian remote sensing GaoFen-3 SAR satellite experiment data processing show that the measurement accuracy of this method is better than 0.002°, which can be applied to the accurate measurement of azimuth pointing of various low Earth orbit (LEO) SAR antenna beams.
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With the rapid development of remote sensing technologies, SAR satellites like China's Gaofen-3 satellite have more imaging modes and higher resolution. With the availability of high-resolution SAR images, automatic ship target detection has become an important topic in maritime research. In this paper, a novel ship detection method based on gradient and integral features is proposed. This method is mainly composed of three steps. First, in the preprocessing step, a filter is employed to smooth the clutters and the smoothing effect can be adaptive adjusted according to the statistics information of the sub-window. Thus, it can retain details while achieving noise suppression. Second, in the candidate area extraction, a sea-land segmentation method based on gradient enhancement is presented. The integral image method is employed to accelerate computation. Finally, in the ship target identification step, a feature extraction strategy based on Haar-like gradient information and a Radon transform is proposed. This strategy decreases the number of templates found in traditional Haar-like methods. Experiments were performed using Gaofen-3 single-polarization SAR images, and the results showed that the proposed method has high detection accuracy and rapid computational efficiency. In addition, this method has the potential for on-board processing.