Showing papers by "Hong Zhang published in 2010"

Group VIA phospholipase A2 in both host and tumor cells is involved in ovarian cancer development

Abstract: Host-tumor cell interactions are recognized to be critical in tumor development. We have shown that group VIA phospholipase A(2) [calcium-independent phospholipase A(2)β (iPLA(2)β)] is important in regulating extracellular lysophosphatidic acid (LPA) levels around human epithelial ovarian cancer (EOC) cells. To explore the role of iPLA(2)β in host-tumor cell interactions, we have used immunocompetent iPLA(2)β knockout (iPLA(2)β(-/-)) mice and the mouse EOC cell line ID8. Tumorigenesis and ascites formation were reduced in iPLA(2)β(-/-) mice compared with wild-type (WT) mice by more >50% and were reduced further when ID8 cell iPLA(2)β levels were lowered (by>95%) with shRNA. LPA and lysophosphatidylcholine (LPC) levels in the tumor microenvironment were reduced to ∼80% of WT levels in iPLA(2)β(-/-) mice. LPA, but not LPC, stimulated ID8 cell migration and invasion with cells in which iPLA(2)β expression had been down-regulated in vitro. LPA, but not LPC, also enhanced in vivo ascites formation (by ∼5-fold) and tumorigenesis in iPLA(2)β(-/-) mice. This is the first demonstration of a role for host cell iPLA(2)β in cancer, and these findings suggest that iPLA(2)β is a potential target for developing novel antineoplastic therapeutic strategies.

Synthetic circuits, devices and modules

Abstract: The aim of synthetic biology is to design artificial biological systems for novel applications. From an engineering perspective, construction of biological systems of defined functionality in a hierarchical way is fundamental to this emerging field. Here, we highlight some current advances on design of several basic building blocks in synthetic biology including the artificial gene control elements, synthetic circuits and their assemblies into devices and modules. Such engineered basic building blocks largely expand the synthetic toolbox and contribute to our understanding of the underlying design principles of living cells.

Ocean-land segmentation based on active contour model for SAR imagery

Abstract: Ocean-land segmentation is a basis for oceanic targets detection for SAR imagery The traditional manual segmentation method can acquire a fairly good result, while it is unable to achieve a satisfying efficiency Thus the manual method is unsuitable for batch processing Ocean map based land masking method requires a priori information, which restricts its application This paper presents an automatic active contour model based ocean-land segmentation method for SAR imagery This method forces the active contour to the real coastline by variation level set Under the restriction of minimizing a given energy function, the method obtains the final segmentation result when the active contour is overlapped on the coastline In addition, an optimizing method is proposed to improve its computation efficiency, which makes our segmentation method more applicable

Ship detection based on compound distribution with Synthetic Aperture Radar images

Abstract: Considering the variability of Synthetic Aperture Radar (SAR) imaging (different sensor, resolution) and complex condition of sea surface, the traditional single statistical model may be no longer a good choice to fit the distribution of actual sea clutter in SAR image. Based on the characteristic of Gamma distribution which is suitable to model uniform area, and GO distribution which is adaptive to the general homogeneous and heterogeneous area, this paper established a compound distribution of GO and Gamma model to fit the characteristics of various types of sea conditions, and use the moment estimation to improve the computational efficiency as well. Meanwhile, the algorithm combines the Constant False Alarm Rate (CFAR) detection based on dichotomy method in order to figure out the difficulties in solving the analytical expression of compound distribution. TerraSAR-X and ERS-2 images were adopted for investigating the algorithm. Experiment results illustrate that the method can achieve good performance.

Change detection in urban areas with high resolution SAR images using second kind statistics based G0 distribution

Abstract: This paper presents a SAR image change detection algorithm for urban areas which mainly contains three steps: (i) modeling the Synthetic Aperture Radar (SAR) image by G0 distribution; (ii) generating a change map by computing the Kullback-Leibler divergence; (iii) masking the change map to obtain the final change areas. We propose to use the second kind statistics based parameter estimation method via Mellin transform to figure out the three parameters of G0 distribution. Experiment results indicate the second kind based G0 distribution model outperforms the moment based methods and can achieve a satisfactory result.

Aircraft discrimination in high resolution SAR images based on texture analysis

Abstract: Target discrimination is the key step of automatic target detection in synthetic aperture radar (SAR) images. Aiming at the issue of aircraft discrimination in high resolution SAR images, a novel discrimination method is proposed with using texture features. First of all the method of gray level co-occurrence matrix is used to generate eight discrimination texture features: mean, variance, deficit moment, inertia moment, entropy, angular second moment, relevance and non-similarity and then forming a feature vector. Differing with the common method of extracting the holistic texture features of image to represent the target, the texture features of each pixel are extracted and the feature vectors of all pixels are used to represent the target. Then J-M distance is used to measure the different targets, and supervised training method is applied to achieve the parameters of discrimination rule. Finally, suspected targets are discriminated to different classes by the trained discrimination rule and large numbers of false alarms are eliminated efficiently. The experiments show that the aircraft has small distance to other aircrafts while large difference to false alarms, so this discrimination method has high accuracy with excellent applicability.

Comparison of polarimetric calibration techniques and their applications

Abstract: Crosstalk calibration is an important part of polarimetric calibration, and the Quegan algorithm and Ainsworth algorithm are classic algorithms to reduce crosstalk. This paper gives analysis and comparison of these algorithms for quad polarized data with low crosstalk and high crosstalk, respectively. The PolSAR data used in experiments are acquired by East China Research Institute of Electronic Engineering over the test site near Sanya City, Hainan Province of China. The results show that Ainsworth algorithm performs well for quad polarized data with low crosstalk, while the Quegan algorithm is applicable for quad polarized data with high crosstalk.

Comparison of Beijing-Tianjin Intercity Railway deformation monitoring results between ASAR and PALSAR data

Abstract: First comparison experiments by different datasets were done to estimate the subsidence pattern of China Beijing-Tianjin Intercity Railway roadbed in Tianjin area in this paper. The multi-baseline differential synthetic aperture radar interferometry technique was used to give the subsidence monitoring. During the period of middle 2008 to middle 2009, the experiment results show that the roadbed is relative stable during the first year running of the Intercity Railway. And the comparison analyses show that both experiment results give the same subsidence rate pattern along the roadbed corridor, meanwhile the PALSAR results give better railway imaged but larger subsidence velocity standard deviation.

Four metazoan autophagy genes regulate cargo recognition, autophagosome formation and autolysosomal degradation.

Abstract: The mechanism responsible for induction and maturation of autophagosomes in multicellular organisms is poorly understood. We performed genetic screens in C. elegans and identified three essential autophagy genes, epg-3, -4 and -5, which have highly conserved homologs in mammals, but are absent in yeast. We also identified a nematode-specific gene, epg-2, that is required for degradation of components of the specialized protein aggregates, called PGL granules. epg-2, -3, -4 and -5 define discrete genetic steps of the autophagy pathway. We further demonstrated that mammalian homologs of EPG-3, -4 and -5 are essential for starvation-induced autophagy. Our study establishes C. elegans as a model to identify components of the basal autophagy pathway specific to higher eukaryotes and to further assemble these genes into genetic pathways.

Aircraft Type Recognition in High-Resolution SAR Images Using Multi-Scale Autoconvolution

Abstract: Automatic target recognition is the key stage of SAR image interpretation system and has been taking a great interest to the researchers in recent years. Aiming at the issue of aircraft type recognition in high-resolution SAR images, a novel method based on multi-scale autoconvolution (MSA) affine invariant moment is proposed. First, the texture analysis and clustering method are used to segment the SAR images and then the denoising algorithm and morphological processing are applied to segmented results. Second, 29 MSA features are extracted and form a feature vector to represent the target, then the vector components are standardized by gauss normalization. In the final, the vectors are classified by using the nearest neighbor classifier and template library constructed previously. Experimental results show that the proposed method can obtain high accuracy rate with high processing speed, in which the accuracy rate of two type aircrafts with real data arrives at 85.17% and the accuracy rate of four type aircrafts with simulated data arrives at 87.85%.

Characteristic analysis of vehicle target in Quad-Pol Radarsat-2 SAR images

Abstract: Radarsat-2 satellite offers general users the Quad-Pol SAR image service with a resolution of 8 meters, which provides valuable data source for the research of traffic vehicles monitoring on Quad-Pol SAR images. According to the vehicle target in such new SAR images, this paper put forward a target characteristic analysis method, which is a combination of target RCS measurement and polarization decomposition. Moreover, it choose the large trucks as an example, give out a conclusion of characteristic analysis of vehicle targets through the on-site synchronous experimental data obtained at different incident angle. Thus provides the research foundation for further exploration of realizing the traffic monitoring with space-born Quad-Pol SAR images.

The Equivalence Analysis for SDH Decomposition and Cameron Decomposition Based on a Unified Three-Component Scattering Model

Abstract: In 1996, Cameron proposed an approach to decompose an arbitrary polarization scattering matrix into three orthogonal components, including nonreciprocal scattering component, maximum symmetric scattering component, and minimum symmetric scattering component. In this paper, based on the analysis of the characteristics of the maximum symmetric scattering component and the minimum symmetric scattering component in Cameron decomposition, a unified three-component scattering model for polarimetric coherent target decomposition is proposed. Pauli decomposition, SDH decomposition and Cameron decomposition can be expressed as a simplified form of the unified model with some certain restriction respectively. In addition, we can prove that SDH decomposition and Cameron decomposition to be equivalent by verification of restrictions consistency.