Improved Sigma Filter for Speckle Filtering of SAR Imagery Jong-Sen Lee; Jen-Hung Wen; Ainsworth, T.L. ...
IEEE transactions on geoscience and remote sensing,
2009-Jan., 2009, 2009-1-00, 20090101, Volume:
47, Issue:
1
Journal Article
Peer reviewed
The Lee sigma filter was developed in 1983 based on the simple concept of two-sigma probability, and it was reasonably effective in speckle filtering. However, deficiencies were discovered in ...producing biased estimation and in blurring and depressing strong reflected targets. The advancement of synthetic aperture radar (SAR) technology with high-resolution data of large dimensions demands better and efficient speckle filtering algorithms. In this paper, we extend and improve the Lee sigma filter by eliminating these deficiencies. The bias problem is solved by redefining the sigma range based on the speckle probability density functions. To mitigate the problems of blurring and depressing strong reflective scatterers, a target signature preservation technique is developed. In addition, we incorporate the minimum-mean-square-error estimator for adaptive speckle reduction. Simulated SAR data are used to quantitatively evaluate the characteristics of this improved sigma filter and to validate its effectiveness. The proposed algorithm is applied to spaceborne and airborne SAR data to demonstrate its overall speckle filtering characteristics as compared with other algorithms. This improved sigma filter remains simple in concept and is computationally efficient but without the deficiencies of the original Lee sigma filter.
Appropriate regulation of crop seed germination is of significance for agriculture production. In this study, we show that TaJAZ1, most closely related to Arabidopsis JAZ3, negatively modulates ...abscisic acid (ABA)-inhibited seed germination and ABA-responsive gene expression in bread wheat. Biochemical interaction assays demonstrate that the C-terminal part containing the Jas domain of TaJAZ1 physically interacts with TaABI5.
Similarly, Arabidopsis jasmonate-ZIM domain (JAZ) proteins also negatively modulate ABA responses. Further we find that a subset of JAZ proteins could interact with ABI5 using the luciferase complementation imaging assays.
Choosing JAZ3 as a representative, we demonstrate that JAZ3 interacts with ABI5 in vivo and represses the transcriptional activation activity of ABI5. ABA application could abolish the enrichment of JAZ proteins in the ABA-responsive gene promoter. Furthermore, we find that ABA application could induce the expression of jasmonate (JA) biosynthetic genes and then increase the JA concentrations partially dependent on the function of ABI5, consequently leading to the degradation of JAZ proteins.
This study sheds new light on the crosstalk between JA and ABA in modulating seed germination in bread wheat and Arabidopsis.
Fleshy fruit texture is a critically important quality characteristic of ripe fruit. Softening is an irreversible process which operates in most fleshy fruits during ripening which, together with ...changes in color and taste, contributes to improvements in mouthfeel and general attractiveness. Softening results mainly from the expression of genes encoding enzymes responsible for cell wall modifications but starch degradation and high levels of flavonoids can also contribute to texture change. Some fleshy fruit undergo lignification during development and post‐harvest, which negatively affects eating quality. Excessive softening can also lead to physical damage and infection, particularly during transport and storage which causes severe supply chain losses. Many transcription factors (TFs) that regulate fruit texture by controlling the expression of genes involved in cell wall and starch metabolism have been characterized. Some TFs directly regulate cell wall targets, while others act as part of a broader regulatory program governing several aspects of the ripening process. In this review, we focus on advances in our understanding of the transcriptional regulatory mechanisms governing fruit textural change during fruit development, ripening and post‐harvest. Potential targets for breeding and future research directions for the control of texture and quality improvement are discussed.
This review focuses on advances in our understanding of the transcriptional regulatory mechanisms governing changes in fruit texture (e.g. softening and lignification) during fruit development, ripening, and postharvest. Potential targets for breeding and future research directions for the control of texture and quality improvement are discussed.
The Soil Moisture Active Passive (SMAP) mission, which is the newest L-band satellite that is specifically designed for soil moisture monitoring, was launched on January 31, 2015. A beta quality ...version of the SMAP radiometer soil moisture product was recently released to the public. It is crucial to evaluate the reliability of this product before it can be routinely used in hydrometeorological studies at a global scale. In this paper, we carried out a preliminary evaluation of the SMAP radiometer soil moisture product against in situ measurements collected from three networks that cover different climatic and land surface conditions, including two dense networks established in the U.S. and Finland, and one sparse network set up in Romania. Results show that the SMAP soil moisture product is in good agreement with the in situ measurements, although it exhibits dry or wet bias at different network regions. It well reproduces the temporal evolution and anomalies of the observed soil moisture with a favorable correlation greater than 0.7. The overall ubRMSE (unbiased root mean square error) of SMAP product is 0.036 m 3 · m -3 , well within the mission requirement of 0.04 m 3 · m -3 . The error sources of SMAP soil moisture product may be associated with the parameterization of vegetation and surface roughness but still needs to be tested and confirmed in more extent. Considering that the algorithms are still under refinement, it can be reasonably expected that hydrometeorological applications will benefit from the SMAP radiometer soil moisture product.
Two of the most influential ideas developed by Richard Feynman are the Feynman diagram technique and his variational approach. Here we show that combining both, and introducing a diagrammatic quantum ...Monte Carlo method, results in a powerful and accurate solver to the generic solid state problem, in which a macroscopic number of electrons interact by the long range Coulomb repulsion. We apply it to the quintessential problem of solid state, the uniform electron gas, which is at the heart of the density functional theory success in describing real materials, yet it has not been adequately solved for over 90 years. Our method allows us to calculate numerically exact momentum and frequency resolved spin and charge response functions. This method can be applied to a number of moderately interacting electron systems, including models of realistic metallic and semiconducting solids.
The Xinmo landslide slope in Sichuan, China, was stable during the intensive Wenchuan Earthquake in 2008 but failed on June 24, 2017. Landslide debris buried Xinmo Village and blocked the Songpinggou ...River at the slope toe. This study aims to clarify the post-failure behavior of the landslide using two-dimensional discontinuous deformation analysis (2D DDA). The simulation results provide comprehensive information on the initiation and the evolution of the landslide. The failure process determined by the DDA correlates well with the seismic signal analysis results. In addition, the location of the calculated rock deposit is similar to that shown by the topographic map after the landslide. The maximum rock velocity in the landslide is 65.4 m/s. Therefore, the impacts of the high-velocity blocks and the buildings in Xinmo Village must be considered to simulate the burial of Xinmo Village by rocks and the transport of additional rocks across the Songpinggou River. This Xinmo landslide study demonstrates that the DDA accurately simulates the post-failure behavior and determines the impact area of a landslide with complicated failure processes and topography.
•The DDA simulates the failure process of the Xinmo landslide.•The initiating behavior and the failure process of the landslide were numerically identified.•The simulated failure process correlates well with the data from the satellite imagery measurements, seismic signal analysis, and the local landform.
Ordered mesoporous transition metal oxides have attracted considerable research attention due to their unique properties and wide applications. The preparation of these materials has been reported in ...the literature using soft and hard templating pathways. Compared with soft templating, hard templating, namely, nanocasting, is advantageous for synthesizing rigid mesostructures with high crystallinity and has already been applied to numerous transition metal oxides such as Co3O4, NiO, Fe2O3, and Mn3O4. However, nanocasting is often complicated by the multiple steps involved: first, the preparation of ordered mesoporous silica as the hard template, then infiltration of the metal precursor into the pores, and finally, formation of the metal oxide and removal of the hard template. In this paper, we provide a complete protocol that covers the preparation of most widely used ordered mesoporous silica templates (MCM-41, KIT-6, SBA-15) and the nanocasting process for obtaining ordered mesoporous metal oxides, with emphasizing cobalt oxide as an example. Characterization of the products is presented, and the factors that can potentially affect the process are discussed.
As one of the largest families of transcription factors (TFs) in plants, R2R3-MYB proteins play crucial roles in regulating a series of plant-specific biological processes. Although the diversity of ...plant R2R3-MYB TFs has been studied previously, the processes and mechanisms underlying the expansion of these proteins remain unclear. Here, we performed evolutionary analyses of plant R2R3-MYB TFs with dense coverage of streptophyte algae and embryophytes. Our analyses revealed that ancestral land plants exhibited 10 subfamilies of R2R3-MYB proteins, among which orthologs of seven subfamilies were present in chlorophytes and charophycean algae. We found that asymmetric gene duplication events in different subfamilies account for the expansion of R2R3-MYB proteins in embryophytes. We further discovered that the largest subfamily of R2R3-MYBs in land plants, subfamily VIII, emerged in the common ancestor of Zygnematophyceae and embryophytes. During plant terrestrialization, six duplication events gave rise to seven clades of subfamily VIII. Subsequently, this TF subfamily showed a tendency for expansion in bryophytes, lycophytes, and ferns and extensively diversified in ancestral gymnosperms and angiosperms in clades VIII-A-1, VIII-D, and VIII-E. In contrast to subfamily VIII, other subfamilies of R2R3-MYB TFs have remained less expanded across embryophytes. The findings regarding phylogenetic analyses, auxiliary motifs, and DNA-binding specificities provide insight into the evolutionary history of plant R2R3-MYB TFs and shed light on the mechanisms underlying the extensive expansion and subsequent sub- and neofunctionalization of these proteins.
Since the knee joint bears the full weight load of the human body and the highest pressure loads while providing flexible movement, it is the body part most vulnerable and susceptible to ...osteoarthritis. In exercise therapy, the early rehabilitation stages last for approximately six weeks, during which the patient works with the physical therapist several times each week. The patient is afterwards given instructions for continuing rehabilitation exercise by him/herself at home. This study develops a rehabilitation exercise assessment mechanism using three wearable sensors mounted on the chest, thigh and shank of the working leg in order to enable the patients with knee osteoarthritis to manage their own rehabilitation progress. In this work, time-domain, frequency-domain features and angle information of the motion sensor signals are used to classify the exercise type and identify whether their postures are proper or not. Three types of rehabilitation exercise commonly prescribed to knee osteoarthritis patients are: Short-Arc Exercise, Straight Leg Raise, and Quadriceps Strengthening Mini-squats. After ten subjects performed the three kinds of rehabilitation activities, three validation techniques including 10-fold cross-validation, within subject cross validation, and leave-one-subject cross validation are utilized to confirm the proposed mechanism. The overall recognition accuracy for exercise type classification is 97.29% and for exercise posture identification it is 88.26%. The experimental results demonstrate the feasibility of the proposed mechanism which can help patients perform rehabilitation movements and progress effectively. Moreover, the proposed mechanism is able to detect multiple errors at once, fulfilling the requirements for rehabilitation assessment.
Animal models have shown that regional anesthesia (combined with or without general anesthesia) would attenuate the surgical stress response by preserving immune function and result in better ...long-term outcome. In order to test the hypothesis that cancer patients who had surgery with epidural anesthesia (EA) would have better outcome (either overall survival OS or recurrence-free survival RFS) than those who were general anesthesia (GA), we performed this meta-analysis. By searching relevant literature, a total of 14 studies containing 18 sub-studies (seven in OS analysis and eleven in RFS analysis) were identified and meta-analyzed. Adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were used to assess the strength of association. For OS, the random-effects model was used to analyze the data and demonstrated an OS benefit in favor of EA compared with GA alone (HR = 0.84, 95% CI 0.74-0.96, P = 0.013). The influence analysis showed the robustness of the results. Specifically, a significantly positive association between EA and improved OS was observed in colorectal cancer (HR = 0.65, 95% CI 0.43-0.99, P = 0.045). For RFS, the random-effects model was used to analyze the data and no significant relationship between RFS benefit and EA (HR = 0.88, 95% CI 0.64-1.22, P = 0.457) was detected. In conclusion, our meta-analysis suggests that epidural anesthesia and/or analgesia might be associated with improved overall survival in patients with operable cancer undergoing surgery (especially in colorectal cancer), but it does not support an association between epidural anesthesia and cancer control. Prospective studies are needed to determine whether the association between epidural use and survival is causative.
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