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Search Results: 1 - 10 of 32952 matches for " Yuchun Guo "
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An Improved Parameters Extraction Method for Dumbbell-Shaped Defected Ground Structure  [PDF]
Yuchun Guo, Qing Wang
Engineering (ENG) , 2010, DOI: 10.4236/eng.2010.23028
Abstract: The paper presents an improved equivalent circuit parameters extraction method for the dumbbell-shaped defected ground structure (DGS). The new extraction parameters equations are obtained in closed-form expressions, which contain S11 and S21. The DGS unit with center frequency of 5 GHz is designed and fabricated on a TLX substrate with thickness of 1 mm and dielectric constant of 2.55. The circuit simulated results are in good agreement with the measured results. This parameters extraction method can be widely used for the design and analysis of DGS .
High Resolution Genome Wide Binding Event Finding and Motif Discovery Reveals Transcription Factor Spatial Binding Constraints
Yuchun Guo,Shaun Mahony ,David K. Gifford
PLOS Computational Biology , 2012, DOI: 10.1371/journal.pcbi.1002638
Abstract: An essential component of genome function is the syntax of genomic regulatory elements that determine how diverse transcription factors interact to orchestrate a program of regulatory control. A precise characterization of in vivo spacing constraints between key transcription factors would reveal key aspects of this genomic regulatory language. To discover novel transcription factor spatial binding constraints in vivo, we developed a new integrative computational method, genome wide event finding and motif discovery (GEM). GEM resolves ChIP data into explanatory motifs and binding events at high spatial resolution by linking binding event discovery and motif discovery with positional priors in the context of a generative probabilistic model of ChIP data and genome sequence. GEM analysis of 63 transcription factors in 214 ENCODE human ChIP-Seq experiments recovers more known factor motifs than other contemporary methods, and discovers six new motifs for factors with unknown binding specificity. GEM's adaptive learning of binding-event read distributions allows it to further improve upon previous methods for processing ChIP-Seq and ChIP-exo data to yield unsurpassed spatial resolution and discovery of closely spaced binding events of the same factor. In a systematic analysis of in vivo sequence-specific transcription factor binding using GEM, we have found hundreds of spatial binding constraints between factors. GEM found 37 examples of factor binding constraints in mouse ES cells, including strong distance-specific constraints between Klf4 and other key regulatory factors. In human ENCODE data, GEM found 390 examples of spatially constrained pair-wise binding, including such novel pairs as c-Fos:c-Jun/USF1, CTCF/Egr1, and HNF4A/FOXA1. The discovery of new factor-factor spatial constraints in ChIP data is significant because it proposes testable models for regulatory factor interactions that will help elucidate genome function and the implementation of combinatorial control.
Fingerprint for Network Topologies
Yuchun Guo,Changjia Chen,Shi Zhou
Physics , 2008, DOI: 10.1007/978-3-642-02469-6_45
Abstract: A network's topology information can be given as an adjacency matrix. The bitmap of sorted adjacency matrix(BOSAM) is a network visualisation tool which can emphasise different network structures by just looking at reordered adjacent matrixes. A BOSAM picture resembles the shape of a flower and is characterised by a series of 'leaves'. Here we show and mathematically prove that for most networks, there is a self-similar relation between the envelope of the BOSAM leaves. This self-similar property allows us to use a single envelope to predict all other envelopes and therefore reconstruct the outline of a network's BOSAM picture. We analogise the BOSAM envelope to human's fingerprint as they share a number of common features, e.g. both are simple, easy to obtain, and strongly characteristic encoding essential information for identification.
A topology visualisation tool for large-scale communications networks
Yuchun Guo,Changjia Chen,Shi Zhou
Computer Science , 2006,
Abstract: A visualisation tool is presented to facilitate the study on large-scale communications networks. This tool provides a simple and effective way to summarise the topology of a complex network at a coarse level.
The Effects of Meteorological Factors Anomalies on Oceanic Coral Reef Systems in the Northwestern South China Sea  [PDF]
Lingli Fan, Yuchun Shen
Journal of Geoscience and Environment Protection (GEP) , 2015, DOI: 10.4236/gep.2015.32004

Climate warming, variation of East Asian atmospheric system have affected the Chinese offshore environment through the air-sea interaction, the coastal waters of South China Sea had been influenced, leading a corresponding impact on the coral reef growth. This paper reports on coral coverage and dominant coral species changes in Xu wen National Coral Reef Nature Reserve, examines their relationship with meteorological factors anomalies recorded by satellite. The study reveals that: compared to the period from 1979 to 2003, the temperature of surface coastal water dropped significantly in South China Sea in 2004-2008, the divergence of low layer of atmosphere over it strengthened, produced a zonal westerly anomaly field, which had an opposite direction to the local northeastern trade wind. The increasing of suspended matter in water, the decreasing of down welling in northwestern South China Sea, made the water quality deteriorating, water transparency decreased significantly, coral reef survival environment worsened, which would cause adverse effects on coral reef building capacity in the Reserve. Continued monitoring efforts are necessary to further assess the relationship between coral building capacity and in situ meteorological factors anomalies and improve the use of the dataset in future regional degradation predictions.

Towards a Holistic, Yet Gene-Centered Analysis of Gene Expression Profiles: A Case Study of Human Lung Cancers
Yuchun Guo,Gabriel S. Eichler,Ying Feng,Donald E. Ingber,Sui Huang
Journal of Biomedicine and Biotechnology , 2006, DOI: 10.1155/jbb/2006/69141
Abstract: Genome-wide gene expression profile studies encompass increasingly large number of samples, posing a challenge to their presentation and interpretation without losing the notion that each transcriptome constitutes a complex biological entity. Much like pathologists who visually analyze information-rich histological sections as a whole, we propose here an integrative approach. We use a self-organizing maps-based software, the gene expression dynamics inspector (GEDI) to analyze gene expression profiles of various lung tumors. GEDI allows the comparison of tumor profiles based on direct visual detection of transcriptome patterns. Such intuitive “gestalt” perception promotes the discovery of interesting relationships in the absence of an existing hypothesis. We uncovered qualitative relationships between squamous cell tumors, small-cell tumors, and carcinoid tumor that would have escaped existing algorithmic classifications. These results suggest that GEDI may be a valuable explorative tool that combines global and gene-centered analyses of molecular profiles from large-scale microarray experiments.
Physiological adaptability of seeding rice genotypes with different P uptake effciency under low P-deficient stress

GUO Yuchun,LIN Wenxiong,SHI Qiumei,LIANG Yiyuan,HE Huaqin,CHEN Fangyu,

应用生态学报 , 2003,
Abstract: The genotypic differences in Puptake efficiency of three rice varieties (IR74, IR71331 and IR71379) were studied under the P-deficiency condition with hydroponics, and their adaptability to low phosphorus stress about physio-biochemical mechanisms was further studied. The results showed that rice genotypes tolerated low P stress resulted from the co-ordination of P uptake efficiency, internal utilization efficiency and its translocation efficiency. The higher P-efficiency type IR74 and the middle type IR71331 had a higher P uptake efficiency. The rice genotype with higher P-efficiency was characterized by higher activity and desirable kinetic parameters of H 2PO 4 - uptake, showing lower K m and C min, but higher I max values and relative APase activity,small amount of K m and C min. Moreover,under low P stress, the activity of RNase was about ten to fifteen times as high as that of the control (CK), but it had little genotypic differences.
Allelopathy and resources competition of rice under different nitrogen supplies

XIONG Jun,LIN Wenxiong,ZHOU Junjian,WU Minhong,CHEN Xiangxu,HE Huaqin,GUO Yuchun,LIANG Yiyuan,

应用生态学报 , 2005,
Abstract: In order to explore the bio-interference of allelopathic rice with barnyardgrass under different nitrogen supplies,a new bioassay method,i.e.,allelopathy-competition separation based (ACS) approach was recommended in this study.The results indicated that ACS could be successfully used to distinguish the rice allelopathy from its resources competition in rice-weed co-culture system,and to evaluate its response characteristics under different N supplies.The test rice accession PI312777 had a higher ability in interfering target weed barnyardgrass (BYD),represented by its stable and higher ability in resources competition,as well as its increasing allelopathic potential in suppressing companion weed BYD when the N supply decreased in the co-cultured system.The reverse was true in the case of rice accession Lemont,which had a lower allelopathic potential under all N supply levels,and a lower ability in resources competition under normal or rich N supply.But,Lemont had an obviously increased ability in resources competition under lower N supply,which was considered as the result of econiche competition in rice-weed system.
The application of the microstructured metallic grating to light emission extraction
YuChun Gou,YiMin Xuan
Chinese Science Bulletin , 2013, DOI: 10.1007/s11434-012-5518-z
Abstract: Microstructured metallic gratings can be used to enhance the light emission efficiency of LEDs, and the spectral radiation properties of the LEDs vary with the different metallic materials used, leading to variation of the light emission enhancement at the same wavelength for different metallic grating materials. In this paper, the finite difference time domain (FDTD) method has been used to investigate the light emission extraction enhancement of LEDs in which gratings with different metallic materials have been applied. Through analysis of the permittivity of the metals and the quality factors of the surface plasmons (SPs), we concluded that the larger the plasma frequency obtained for the metallic interband transition, then the more suitable the metals are for light emission extraction of photons with relatively short wavelengths. This is because of the abundance of free electrons in the metals with large plasma frequencies. We also found that the wavelength-dependent trends of the extraction enhancement resulting from the scattering mechanism for different metallic materials are similar to each other. For SP-induced enhancement, either the enhancement peak position or the peak value changes significantly with the different metals.
An H5N1 M2e-based multiple antigenic peptide vaccine confers heterosubtypic protection from lethal infection with pandemic 2009 H1N1 virus
Guangyu Zhao, Shihui Sun, Lanying Du, Wenjun Xiao, Zhitao Ru, Zhihua Kou, Yan Guo, Hong Yu, Shibo Jiang, Yuchun Lone, Bo-Jian Zheng, Yusen Zhou
Virology Journal , 2010, DOI: 10.1186/1743-422x-7-151
Abstract: Our results demonstrated that H5N1-M2e-MAP plus Freund's or aluminum adjuvant induced strong cross-reactive IgG antibody responses against M2e of the pandemic H1N1 virus which contains one amino acid variation with M2e of H5N1 at position 13. These cross-reactive antibodies may maintain for 6 months and bounced back quickly to the previous high level after the 2nd boost administered 2 weeks before virus challenge. H5N1-M2e-MAP could afford heterosubtypic protection against lethal challenge with pandemic H1N1 virus, showing significant decrease of viral replications and obvious alleviation of histopathological damages in the challenged mouse lungs. 100% and 80% of the H5N1-M2e-MAP-vaccinated mice with Freund's and aluminum adjuvant, respectively, survived the lethal challenge with pandemic H1N1 virus.Our results suggest that H5N1-M2e-MAP has a great potential to prevent the threat from re-emergence of pandemic H1N1 influenza and possible novel influenza pandemic due to the reassortment of HPAI H5N1 virus with the 2009 swine-origin H1N1 influenza virus.At the same time concern was raised about a possible pandemic resulting from the highly pathogenic avian influenza (HPAI) H5N1 virus, the world confronted the first influenza pandemic of the 21st century caused by a novel influenza A H1N1 virus [1]. This pandemic H1N1 virus was first identified in April 2009 and demonstrated a rapid rate of spread. As of 9 May, 2010, WHO has reported at least 18,036 fatal cases in more than 214 countries [2]. Although H5N1 virus has not yet evolved to become transmissible among humans, it has still presented a high mortality rate of approximately 60% [3]. Consequently, WHO considers the H5N1 virus to be a potential human pandemic [4]. Antigenic and genetic analysis has suggested that the current pandemic 2009 H1N1 virus is a product of reassortment between genes in the human, avian and swine influenza strains [5]. There is a concern that one more human pandemic influenza virus could be
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