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Search Results: 1 - 10 of 80945 matches for " Shiguo Liu "
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Recent Advances in the Photorefraction of Doped Lithium Niobate Crystals
Yongfa Kong,Shiguo Liu,Jingjun Xu
Materials , 2012, DOI: 10.3390/ma5101954
Abstract: The recent advances in the photorefraction of doped lithium niobate crystals are reviewed. Materials have always been the main obstacle for commercial applications of photorefractive holographic storage. Though iron-doped LiNbO 3 is the mainstay of holographic data storage efforts, several shortcomings, especially the low response speed, impede it from becoming a commercial recording medium. This paper reviews the photorefractive characteristics of different dopants, especially tetravalent ions, doped and co-doped LiNbO 3 crystals, including Hf, Zr and Sn monodoped LiNbO 3, Hf and Fe, Zr and Fe doubly doped LiNbO 3, Zr, Fe and Mn, Zr, Cu and Ce triply doped LiNbO 3, Ru doped LiNbO 3, and V and Mo monodoped LiNbO 3. Among them, Zr, Fe and Mn triply doped LiNbO 3 shows excellent nonvolatile holographic storage properties, and V and Mo monodoped LiNbO 3 has fast response and multi-wavelength storage characteristics.
Investigation on p-type lithium niobate crystals
Zidong Pei,Qian Hu,Yongfa Kong,Shiguo Liu
AIP Advances , 2011, DOI: 10.1063/1.3647503
Abstract: Till now it is difficult to obtain a p-type lithium niobate crystal. Here the carrier types in various doped and oxidized LiNbO3 crystals have been investigated by holographic technique. The experimental results show tetravalent ions (Zr4+ and Hf4+) with doping concentrations just above optical damage resistant thresholds is helpful to increase the concentration of holes. And 3.0 mol% ZrO2 doped LiNbO3 can be used as a p-type crystal. The dominant carrier of iron doped LiNbO3 crystal can be changed to holes when treated by thermo-electric oxidization. Then the possible mechanism on how to obtain a p-type LiNbO3 was discussed.
Improved LSB-matching Steganography for Preserving Second-order Statistics
Guangjie Liu,Zhan Zhang,Yuewei Dai,Shiguo Lian
Journal of Multimedia , 2010, DOI: 10.4304/jmm.5.5.458-463
Abstract: In the paper, for enhancing the security of the traditional LSB matching, two improved LSB-matching methods are proposed. In the steganograhical procedure, the Markov chain distance based on the second-order statistics is chosen as the security metric to control the modification directions of ±1 embedding. The first method is based on stochastic modification, which directly determines the modification directions by the empirical Markov transition matrix of a cover image and the pseudorandom number generated by a pseudorandom number generator. The second one is based on genetic algorithm, which is used to find the optimum matching vector to make the security metric as small as possible. Experiments show the proposed algorithms outperform LSB matching and LSB replacement in a sense of the firstorder and second-order security metrics. And the adjacent calibrated COM-HCF steganalytical tests also show that the two algorithms are more secure than the traditional ones.
On the Performance of Joint Fingerprint Embedding and Decryption Scheme
Shiguo Lian,Zhongxuan Liu,Zhen Ren,Haila Wang
Computer Science , 2007,
Abstract: Till now, few work has been done to analyze the performances of joint fingerprint embedding and decryption schemes. In this paper, the security of the joint fingerprint embedding and decryption scheme proposed by Kundur et al. is analyzed and improved. The analyses include the security against unauthorized customer, the security against authorized customer, the relationship between security and robustness, the relationship between secu-rity and imperceptibility and the perceptual security. Based these analyses, some means are proposed to strengthen the system, such as multi-key encryp-tion and DC coefficient encryption. The method can be used to analyze other JFD schemes. It is expected to provide valuable information to design JFD schemes.
Image Authentication Based on Neural Networks
Shiguo Lian
Computer Science , 2007,
Abstract: Neural network has been attracting more and more researchers since the past decades. The properties, such as parameter sensitivity, random similarity, learning ability, etc., make it suitable for information protection, such as data encryption, data authentication, intrusion detection, etc. In this paper, by investigating neural networks' properties, the low-cost authentication method based on neural networks is proposed and used to authenticate images or videos. The authentication method can detect whether the images or videos are modified maliciously. Firstly, this chapter introduces neural networks' properties, such as parameter sensitivity, random similarity, diffusion property, confusion property, one-way property, etc. Secondly, the chapter gives an introduction to neural network based protection methods. Thirdly, an image or video authentication scheme based on neural networks is presented, and its performances, including security, robustness and efficiency, are analyzed. Finally, conclusions are drawn, and some open issues in this field are presented.
On the Robustness of the Delay-Based Fingerprint Embedding Scheme
Shiguo Lian
Computer Science , 2008,
Abstract: The delay-based fingerprint embedding was recently proposed to support more users in secure media distribution scenario. In this embedding scheme, some users are assigned the same fingerprint code with only different embedding delay. The algorithm's robustness against collusion attacks is investigated. However, its robustness against common desynchronization attacks, e.g., cropping and time shifting, is not considered. In this paper, desynchronization attacks are used to break the delay-based fingerprint embedding algorithm. To improve the robustness, two means are proposed to keep the embedded fingerprint codes synchronized, i.e., adding a synchronization fingerprint and adopting the relative delay to detect users. Analyses and experiments are given to show the improvements.
Secure Fractal Image Coding
Shiguo Lian
Computer Science , 2007,
Abstract: In recent work, various fractal image coding methods are reported, which adopt the self-similarity of images to compress the size of images. However, till now, no solutions for the security of fractal encoded images have been provided. In this paper, a secure fractal image coding scheme is proposed and evaluated, which encrypts some of the fractal parameters during fractal encoding, and thus, produces the encrypted and encoded image. The encrypted image can only be recovered by the correct key. To keep secure and efficient, only the suitable parameters are selected and encrypted through in-vestigating the properties of various fractal parameters, including parameter space, parameter distribu-tion and parameter sensitivity. The encryption process does not change the file format, keeps secure in perception, and costs little time or computational resources. These properties make it suitable for secure image encoding or transmission.
MCP-1-Induced Histamine Release from Mast Cells Is Associated with Development of Interstitial Cystitis/Bladder Pain Syndrome in Rat Models
Jianwei Lv,Yiran Huang,Shiguo Zhu,Ganggang Yang,Yujian Zhang,Jing Leng,Juanjie Bo,Dongming Liu
Mediators of Inflammation , 2012, DOI: 10.1155/2012/358184
Abstract: Objective. Interstitial cystitis/bladder pain syndrome (IC/BPS) is characterized by overexpression of monocyte chemoattractant protein-1 (MCP-1) in bladder tissues and induction of mast cell (MC) degranulation. This study was undertaken to explore the mechanism of action of MCP-1 in the development of IC/BPS. Methods. A rat model of IC/BPS was developed by perfusing bladders of nine SPF- grade female Sprague-Dawley rats with protamine sulfate and lipopolysaccharide (PS+LPS). MCP-1 and histamine levels in bladder tissue and urine were detected by immunohistochemistry and ELISA. MC degranulation was measured by immunofluorescence techniques and chemokine (C-C motif) receptor 2 (CCR2) was assayed by flow cytometry. Results. Increased MCP-1 expression in bladder tissue and elevated MCP-1 and histamine levels were observed in the urine of LS+LPS-treated rats. This was accompanied by the expression of CCR2 on MC surfaces, suggesting MCP-1 may induce MC degranulation through CCR2. Exposure to LPS stimulated MCP-1 expression in bladder epithelial cells, and exposure to MCP-1 induced histamine release from MCs. Conclusions. MCP-1 upregulation in IC/BPS is one of possible contributing factors inducing histamine release from MCs. CCR2 is involved in the process of mast cell degranulation in bladder tissues. These changes may contribute to the development of symptoms of IC/BPS. 1. Introduction Interstitial cystitis/bladder pain syndrome (IC/BPS) is a chronic inflammatory condition that is difficult to characterize without precise knowledge of the symptoms and histology that characterizes the disease [1]. Commonly observed symptoms include urinary frequency, urgency, and suprapublic pain that often drastically affect the quality of life of affected patients [2–4]. It is generally thought that the development and progression of IC/BPS is associated with infection, defects in bladder permeability, immune or neuroendocrine disorders, and genetic disorders related to visceral hypersensitivity [5–7]. Despite comprehensive characterization of symptoms and histology of IC/BPS in recent decades, its exact etiology remains unclear, limiting the development of effective therapeutic interventions. Mast cells (MCs), long suspected to play a role in the onset of IC/BPS, are derived from specific precursors localized in the bone marrow [8]. These precursors are stimulated to maturation by local tissue microenvironmental factors that vary according to the tissue types [9]. MC stimulation has been shown to facilitate the degranulation and release of vasoactive, proinflammatory, and
Stromal proteome expression profile and muscle-invasive bladder cancer research
Haitao Niu, Haiping Jiang, Bo Cheng, Xinhui Li, Qian Dong, Leping Shao, Shiguo Liu, Xinsheng Wang
Cancer Cell International , 2012, DOI: 10.1186/1475-2867-12-39
Abstract: We identified 868/872 commonly expressed proteins and 978 differential proteins from 4 paired cancer and normal stromal samples using laser capture micro dissection coupled with two-dimensional liquid chromatography tandem mass spectrometry. 487/491 proteins uniquely expressed in cancer/normal stroma. Differential proteins were compared with the entire list of the international protein index (IPI), and there were 42/42 gene ontology (GO) terms exhibited as enriched and 8/5 exhibited as depleted in cellular Component, respectively. Significantly altered pathways between cancer/normal stroma mainly include metabolic pathways, ribosome, focal adhesion, etc. Finally, descriptive statistics show that the stromal proteins with extremes of PI and MW have the same probability to be a biomarker.Based on our results, stromal cells are essential component of the cancer, biomarker discovery and network based multi target therapy should consider neoplastic cells itself and corresponding stroma as whole one.Despite recent advances in surgical techniques, perioperative chemo radiotherapy and the development of molecularly targeted therapies, muscle-invasive bladder transitional cell carcinoma (BTCC) is still a major epidemiological problem whose incidence continues to rise each year [1]. The prognosis of muscle-invasive BTCC is poor and the 5-year disease specific survival after radical cystectomy remains 50–60% [2]. Though some molecular pathogenesis studies on invasive bladder carcinoma have been undertaken successfully on the gene and transcription levels, the carcinogenic mechanism remains to be elucidated. In this regard, using stroma as a sample may be an alterative way to study muscle-invasive BTCC carcinogenesis. However, there has been no report of this item.As one of the solid tumors, muscle-invasive BTCC are composed of two independent while interactive components: the neoplastic epithelial cells and the surrounding cancer stroma. These two components interactive and in
Whole Exome Sequencing Identifies Recessive PKHD1 Mutations in a Chinese Twin Family with Caroli Disease
Xiwei Hao, Shiguo Liu, Qian Dong, Hong Zhang, Jing Zhao, Lin Su
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0092661
Abstract: Background Mutations in PKHD1 cause autosomal recessive Caroli disease, which is a rare congenital disorder involving cystic dilatation of the intrahepatic bile ducts. However, the mutational spectrum of PKHD1 and the phenotype-genotype correlations have not yet been fully established. Methods Whole exome sequencing (WES) was performed on one twin sample with Caroli disease from a Chinese family from Shandong province. Routine Sanger sequencing was used to validate the WES and to carry out segregation studies. We also described the PKHD1 mutation associated with the genotype-phenotype of this twin. Results A combination of WES and Sanger sequencing revealed the genetic defect to be a novel compound heterozygous genotype in PKHD1, including the missense mutation c.2507 T>C, predicted to cause a valine to alanine substitution at codon 836 (c.2507T>C, p.Val836Ala), and the nonsense mutation c.2341C>T, which is predicted to result in an arginine to stop codon at codon 781 (c.2341C>T, p.Arg781*). This compound heterozygous genotype co-segregates with the Caroli disease-affected pedigree members, but is absent in 200 normal chromosomes. Conclusions Our findings indicate exome sequencing can be useful in the diagnosis of Caroli disease patients and associate a compound heterozygous genotype in PKHD1 with Caroli disease, which further increases our understanding of the mutation spectrum of PKHD1 in association with Caroli disease.
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