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Search Results: 1 - 10 of 44270 matches for " Yunfeng Wu "
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Evolution and frontogenesis of an imbalanced flow —the influence of vapor distribution and orographie forcing
Evolution and Frontogenesis of an Imbalanced Flow —the Influence of Vapor Distribution and Orographic Forcing

Wang Yunfeng,Wu Rongsheng,Pan Yinong,
Wang Yunfeng
,Wu Rongsheng,Pan Yinong

大气科学进展 , 2000,
Abstract: If the initial fields are not in geostrophic balance, the adjustment and evolution will occur in the stratified fluid, and the frontogenesis will occur under suitable conditions. The evolution is studied here with a nonhydrostatic fully compressible meso-scale model (Advanced Regional Prediction System, ARPS). Four cases are designed and compared: (i) control experiment; (ii) with different initial temperature gradient; (iii) with vapor distribution; (iv) with orographic forcing. The results show that: (1) there is an inertial oscillation in the evolution of the imbalanced flow with the frequency of the local Coriolis f, and with its amplitude de-creasing with time. The stationary balanced state can only be approached as it cannot be reached in the limit duration of time, The energy conversion ratio varies in the range of 0, 1 / 3]; (2) the stronger initial tempera-ture gradient can make the final energy conversion ratio higher, and vice versa; (3) suitable vapor distribu-tion is favorable for the frontogenesis. It will bring forward the time of the frontogenesis, strengthen the in-tensity of the cold front, and influence the final energy conversion ratio; (4) the orographic forcing has an ev-idently strengthening effect on the frontogenesis. The strengthening effect on the frontogenesis and the influ-ence on the final energy conversion ratio depend on the relative location of the mountain to the cold front.
Evolution and Frontogenesis of an Imbalanced Flow- the Influence of Vapor Distribution and Orographic Forcing
Evolution and Frontogenesis of an Imbalanced Flow —the Influence of Vapor Distribution and Orographic Forcing

Wang Yunfeng,Wu Rongsheng,Pan Yinong,
Wang Yunfeng
,Wu Rongsheng,Pan Yinong

大气科学进展 , 2000,
Abstract: If the initial fields are not in geostrophic balance, the adjustment and evolution will occur in the stratified fluid, and the frontogenesis will occur under suitable conditions. The evolution is studied here with a nonhydrostatic fully compressible meso-scale model (Advanced Regional Prediction System, ARPS). Four cases are designed and compared: (i) control experiment; (n) with different initial temperature gradient; (iii) with vapor distribution; (iv) with orographic forcing. The results show that: (l) there is an inertial oscillation in the evolution of the imbalanced flow with the frequency of the local Coriolis f, and with its amplitude decreasing with time. The stationary balanced state can only be approached as it cannot be reached in the limit duration of time. The energy conversion ratio varies in the range of 0, 1 / 3]; (2) the stronger initial temperature gradient can make the final energy conversion ratio higher, and vice versa; (3) suitable vapor distribution is favorable for the frontogenesis. It will bring forward the time of the frontogenesis, strengthen the intensity of the cold front, and innuence the final energy conversion ratin; (4) the orographic forcing has an evidently strengthening effect on the frontogenesis. The strengthening effect on the frontogenesis and the influence on the final energy conversion ratio depend on the relative location of the mountain to the cold front.
Functional significance of the hepaCAM gene in bladder cancer
Yunfeng He, Xiaohou Wu, Chunli Luo, Lie Wang, Jie Lin
BMC Cancer , 2010, DOI: 10.1186/1471-2407-10-83
Abstract: HepaCAM expression was evaluated in 28 normal and 34 TCCB bladder specimens and 2 TCCB cell lines using semi-quantitative RT-PCR. The wild-type hepaCAM and the extracellular domain-truncated mutant gene were transfected into the TCCB cell line T24, and the biological properties of both the wild-type gene and the domain-truncated mutant were then assessed.HepaCAM expression was down-regulated in 82% (28/34) of TCCB specimens and undetectable in the 2 TCCB cell lines tested. The localization of hepaCAM appeared to be dependent on cell density in T24 cells. In widely spread cells, hepaCAM accumulated on the perinuclear membrane and the cell surface protrusions, whereas in confluent cells, hepaCAM was predominantly localized at the sites of cell-cell contacts on the cell membrane. Functionally, hepaCAM expressed not only increased cell spreading, delayed cell detachment, enhanced wound healing and increased cell invasion; it also inhibited cell growth (P < 0.01). When the extracellular domain was deleted, the localization of hepaCAM was significantly altered, and it lost both its adhesive function and its influence on cell growth.HepaCAM is involved in cell adhesion and growth control, and its expression is frequently silenced in TCCB. The extracellular domain of hepaCAM is essential to its physiological and biological functions.Cell-cell and cell-matrix adhesion is essential for normal organogenesis and for the maintenance of normal tissues in humans. This adhesion is largely mediated by a large and complex number of adhesion molecules expressed on the cell surface [1]. They are generally classified into four types based on their structural and functional features: cadherins, selectins, integrins, and members of the immunoglobulin superfamily (IgSF) [2-5]. An exciting concept that has recently emerged from recent cell biological research is that cell adhesion complexes are not simply static architectural entities that play a role in cell-cell and cell-matrix adhesion.
Measurement of GaAs start duration in different solution concentration using infrared images
Lin Liu,YuTang Ye,YunFeng Wu,Liang Fang,JiaJia Lu
Chinese Science Bulletin , 2008, DOI: 10.1007/s11434-008-0012-3
Abstract: This paper proposes a new infrared method to measure the start duration of GaAs substrate in chemical etching. When etching starts, the temperature of liquid-film will change because of heat release in the chemical reaction. As a result, the start duration of GaAs can be tested by collecting real-time infrared thermal images in the course of temperature variation. Both theoretical analysis and experimental results show that the line shape liquid film of a 2-mm width is a good monitoring subject. By making use of the grey distribution change of a certain cross section of the line shape liquid film, the start duration of reaction between GaAs and H2SO4-H2O2-H2O is obtained. The start durations of reaction between GaAs substrate and H2SO4:H2O2:H2O (=5:1:50 and 15:3:50) solution are about 0.2 s and 0.3–0.4 s, respectively. This result and relative method will impulse the research of wet chemical etching technology of GaAs and so on.
Characterization of sequences downstream from transcriptional start site ofRhizobium meliloti nifHDK promoter
Yunfeng Gao,Tong Wu,Jiabi Zhu,Guanqiao Yu,Shanjiong Shen
Science China Life Sciences , 1997, DOI: 10.1007/BF02882051
Abstract: In freeliving state, the nifHDK promoter P1 ofRhizbium meliloti is induced in response to microaerobiosis and expressed to a high level, while the fixABCX promoter P2 is not. The sequences upstream from both P1 and P2 share extended homology (about 85%), which are about 160 bp in length, but the sequences downstream of the respective transcriptional start site are different. When the downstream sequence (DS) of P2 was replaced by the corresponding fragment from+ 17 to + 61 of P1, the expression of P2 is greatly increased under freeliving condition by lowering the oxygen tension, and the activity of P2 promoter can also be significantly enhanced inE. coli by the NifA protein. The difference between the DS regions of P1 and P2 promoter resulted in different expressions of P1 and P2 promoter under freeliving microaerobic condition and inE. coli. The expression of P2 does not depend on the downstream sequences from the promoter element during symbiosis. Primer extension experiments identified the transcriptional start site of P2. Transcription from P2 was not changed when P2 promoter region was inserted by P1 DS. Under symbiotic conditions, levels of expression of P2 were independent of the P1 DS region. It indicates that the regulations of P2 under symbiotic conditions are different from those under freeliving conditions.
Research on phosphorus removal from Chao Lake water with modified diatomite
改性硅藻土用于巢湖水脱磷研究

Wu Lei,Chen Yunfeng,
吴蕾
,陈云峰

环境工程学报 , 2011,
Abstract: 采用改性硅藻土强化混凝处理巢湖水,以达到除磷的目的。研究了改性硅藻土除磷最适操作条件,并将改性硅藻土同几种常规混凝剂的处理效果和其经济性进行了对比。结果表明:改性硅藻土和水的混合搅拌速度梯度为260 s-1左右,絮凝反应速度梯度为20 s-1左右,絮凝时间15 min,沉淀时间1 h,改性硅藻土投加量50~100 mg/L时,可达到较佳的处理效果。TP去除率基本在85%以上,甚至高达99%,出水TP浓度均可达到地表水环境质量标准(GB3838-2002)(湖库)中Ⅵ类水标准,部分可达Ⅱ类甚至Ⅰ类水标准。与常规混凝剂相比,改性硅藻土出水更为清澈透亮,污泥沉降性能好,污泥量少,在建设成本和运行成本上更为节省。
Classification of Knee Joint Vibration Signals Using Bivariate Feature Distribution Estimation and Maximal Posterior Probability Decision Criterion
Yunfeng Wu,Suxian Cai,Shanshan Yang,Fang Zheng,Ning Xiang
Entropy , 2013, DOI: 10.3390/e15041375
Abstract: Analysis of knee joint vibration or vibroarthrographic (VAG) signals using signal processing and machine learning algorithms possesses high potential for the noninvasive detection of articular cartilage degeneration, which may reduce unnecessary exploratory surgery. Feature representation of knee joint VAG signals helps characterize the pathological condition of degenerative articular cartilages in the knee. This paper used the kernel-based probability density estimation method to model the distributions of the VAG signals recorded from healthy subjects and patients with knee joint disorders. The estimated densities of the VAG signals showed explicit distributions of the normal and abnormal signal groups, along with the corresponding contours in the bivariate feature space. The signal classifications were performed by using the Fisher’s linear discriminant analysis, support vector machine with polynomial kernels, and the maximal posterior probability decision criterion. The maximal posterior probability decision criterion was able to provide the total classification accuracy of 86.67% and the area (Az) of 0.9096 under the receiver operating characteristics curve, which were superior to the results obtained by either the Fisher’s linear discriminant analysis (accuracy: 81.33%, Az: 0.8564) or the support vector machine with polynomial kernels (accuracy: 81.33%, Az: 0.8533). Such results demonstrated the merits of the bivariate feature distribution estimation and the superiority of the maximal posterior probability decision criterion for analysis of knee joint VAG signals.
Comparative Genome Analysis of Wheat Blue Dwarf Phytoplasma, an Obligate Pathogen That Causes Wheat Blue Dwarf Disease in China
Wang Chen, Yan Li, Qiang Wang, Nan Wang, Yunfeng Wu
PLOS ONE , 2014, DOI: 10.1371/journal.pone.0096436
Abstract: Wheat blue dwarf (WBD) disease is an important disease that has caused heavy losses in wheat production in northwestern China. This disease is caused by WBD phytoplasma, which is transmitted by Psammotettix striatus. Until now, no genome information about WBD phytoplasma has been published, seriously restricting research on this obligate pathogen. In this paper, we report a new sequencing and assembling strategy for phytoplasma genome projects. This strategy involves differential centrifugation, pulsed-field gel electrophoresis, whole genome amplification, shotgun sequencing, de novo assembly, screening of contigs from phytoplasma and the connection of phytoplasma contigs. Using this scheme, the WBD phytoplasma draft genome was obtained. It was comprised of six contigs with a total size of 611,462 bp, covering ~94% of the chromosome. Five-hundred-twenty-five protein-coding genes, two operons for rRNA genes and 32 tRNA genes were identified. Comparative genome analyses between WBD phytoplasma and other phytoplasmas were subsequently carried out. The results showed that extensive arrangements and inversions existed among the WBD, OY-M and AY-WB phytoplasma genomes. Most protein-coding genes in WBD phytoplasma were found to be homologous to genes from other phytoplasmas; only 22 WBD-specific genes were identified. KEGG pathway analysis indicated that WBD phytoplasma had strongly reduced metabolic capabilities. However, 46 transporters were identified, which were involved with dipeptides/oligopeptides, spermidine/putrescine, cobalt and Mn/Zn transport, and so on. A total of 37 secreted proteins were encoded in the WBD phytoplasma chromosome and plasmids. Of these, three secreted proteins were similar to the reported phytoplasma virulence factors TENGU, SAP11 and SAP54. In addition, WBD phytoplasma possessed several proteins that were predicted to play a role in its adaptation to diverse environments. These results will provide clues for research on the pathogenic mechanisms of WBD phytoplasma and will also provide a perspective about the genome sequencing of other phytoplasmas and obligate organisms.
Current blockade mechanism for DNA translocationthrough solid-state nanopore with different membrane thickness
Wu Gensheng, Zhang Yin, Si Wei, Gu Yunfeng, Chen Yunfei
- , 2016, DOI: 10.3969/j.issn.1003-7985.2016.03.007
Abstract: The current blockade mechanism for λ-DNA translocation under electrical field is investigated through solid-state nanopores with different pore thicknesses. The conductance of a nanopore system mainly consists of the contribution of the pore and access region, and the latter becomes dominant when the nanopore thickness gradually decreases to atomic layer thickness. Based on the existing model of nanopore resistance, a simplified model which describes the relative current blockade during the λ-DNA translocation through the nanopores is deduced to quantitatively present the relationship between nanopore thickness and relative current blockade. Results show that the relative current blockade is effectively increased by reducing the nanopore diameter but it decreases with the decreasing nanopore thickness. A two-stage schematic is proposed to increase the relative current blockade by setting a much smaller resistance region. Experimental results show a 21.9% increase in the relative current blockade with the proposed schematic.
Application of Variational Algorithms in Semi-Lagrangian Framework
Wang Yunfeng,Wu Rongsheng,Wang Yuan,Pan Yinong,
Wang Yunfeng
,Wu Rongsheng,Wang Yuan,Pan Yinong

大气科学进展 , 1999,
Abstract: The variational data assimilation scheme (VAR) is applied to investigating the advective effect and the evolution of the control variables in time splitting semi-Lagrangian framework. Two variational algorithms are used. One is the conjugate code method-direct approach, and another is the numerical backward integration of analytical adjoint equation-indirect approach.Theoretical derivation and sensitivity tests are conducted in order to verify the consistency and inconsistency of the two algorithms under the semi-Lagrangian framework. On the other hand, the sensitivity of the perfect and imperfect initial condition is also tested in both direct and indirect approaches. Our research has shown that the two algorithms are not only identical in theory, but also iden?tical in numerical calculation. Furthermore, the algorithms of the indirect approach are much more feasible and efficient than that of the direct one when both are employed in the semi-Lagrangian framework. Taking advantage of semi-Lagrangian framework, one purpose of this paper is to illustrate when the variational assimilation algorithm is concerned in the computational method of the backward integration, the algorithm is extremely facilitated. Such simplicity in indirect approach should be meaningful for the VAR design in passive model. Indeed, if one can successfully split the diabatic and adiabatic process, the algorithms represented in this paper might be easily used in a more general vision of atmospheric model.
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