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Search Results: 1 - 10 of 25807 matches for " Gang Ren "
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IPET and FETR: Experimental Approach for Studying Molecular Structure Dynamics by Cryo-Electron Tomography of a Single-Molecule Structure
Lei Zhang, Gang Ren
PLOS ONE , 2012, DOI: 10.1371/journal.pone.0030249
Abstract: The dynamic personalities and structural heterogeneity of proteins are essential for proper functioning. Structural determination of dynamic/heterogeneous proteins is limited by conventional approaches of X-ray and electron microscopy (EM) of single-particle reconstruction that require an average from thousands to millions different molecules. Cryo-electron tomography (cryoET) is an approach to determine three-dimensional (3D) reconstruction of a single and unique biological object such as bacteria and cells, by imaging the object from a series of tilting angles. However, cconventional reconstruction methods use large-size whole-micrographs that are limited by reconstruction resolution (lower than 20 ?), especially for small and low-symmetric molecule (<400 kDa). In this study, we demonstrated the adverse effects from image distortion and the measuring tilt-errors (including tilt-axis and tilt-angle errors) both play a major role in limiting the reconstruction resolution. Therefore, we developed a “focused electron tomography reconstruction” (FETR) algorithm to improve the resolution by decreasing the reconstructing image size so that it contains only a single-instance protein. FETR can tolerate certain levels of image-distortion and measuring tilt-errors, and can also precisely determine the translational parameters via an iterative refinement process that contains a series of automatically generated dynamic filters and masks. To describe this method, a set of simulated cryoET images was employed; to validate this approach, the real experimental images from negative-staining and cryoET were used. Since this approach can obtain the structure of a single-instance molecule/particle, we named it individual-particle electron tomography (IPET) as a new robust strategy/approach that does not require a pre-given initial model, class averaging of multiple molecules or an extended ordered lattice, but can tolerate small tilt-errors for high-resolution single “snapshot” molecule structure determination. Thus, FETR/IPET provides a completely new opportunity for a single-molecule structure determination, and could be used to study the dynamic character and equilibrium fluctuation of macromolecules.
Access Control for Manufacturing Process in Networked Manufacturing Environment  [PDF]
Ke Zhou, Min Lv, Gang Wang, Bingyin Ren
Journal of Service Science and Management (JSSM) , 2009, DOI: 10.4236/jssm.2009.22014
Abstract: The deficiencies of current access control techniques in solving the problems of manufacturing process access conflict in networked manufacturing environment were analyzed. An information model of manufacturing process was con-structed, and a case XML Schema of manufacturing task model was given. Based on the characteristic analysis of the access control for the information model, an improved access control model of manufacturing process was constructed, and the access control model based on manufacture tasks, roles and time limits and the relationships among the ele-ments were defined. The implementation mechanisms for access control model were analyzed, in which the access case matching strategy based on manufacture tasks and time limits, the authorization assignment mechanism based on manufacture tasks, roles, correlation degrees and time limits, XML based access control for transaction security and integrity were included. And the two-level detection architecture of transaction conflict was designed to find the con-flicts both in application and in the database. Finally the prototype system was developed based on these principles. Feasibility and effectiveness of the method were verified by an enterprise application.
LHC Evidence Of A 126 GeV Higgs Boson From $H \to γγ$ With Three And Four Generations
Gang Guo,Bo Ren,Xiao-Gang He
Physics , 2011,
Abstract: Searches for Higgs boson at the LHC have excluded standard model (SM) Higgs boson mass in the range between 127 GeV to 600 GeV. With a fourth generation, the excluded range is wider. To close the windows between 114 GeV to 127 GeV, the mode $H \to \gamma\gamma$ plays an important role. There are evidences that the Higgs boson mass is about 126 GeV from LHC data. $H\to \gamma\gamma$ can occur at one loop level in the SM. In the SM with three generations (SM3), the dominant contribution is from W boson with some cancellation from top quark in the loop. With SM4, the large mass of the fourth generation quarks and charged lepton cancel the W boson contribution significantly, the decay width is suppressed by a factorin the range of 0.25 $\sim$ 0.55 for the fourth generation mass in the range of 500 to 1000 GeV. This reduction factor makes $\sigma(pp\to H X)Br(H\to \gamma \gamma)$ for SM4 comparable to that for SM3 for Higgs boson mass in the window allowed mentioned earlier. Using $H \to \gamma \gamma$ alone, therefore, it is difficult at present to distinguish whether the Higgs boson is from SM3 or SM4. We also comments on some other detection channels.
Existence of solutions for multi-point nonlinear differential equations of fractional orders with integral boundary conditions
Gang Wang,Wenbin Liu,Can Ren
Electronic Journal of Differential Equations , 2012,
Abstract: In this article, we study the multi-point boundary-value problem of nonlinear fractional differential equation $$displaylines{ D^alpha_{0+}u(t)=f(t,u(t)),quad 10,cr I_{0+}^{2-alpha}u(t)|_{t=0}=0,quad D_{0+}^{alpha-2}u(T)=sum_{i=1}^ma_i I_{0+}^{alpha-1}u(xi_i), }$$ where $D_{0^+}^alpha$ and $I_{0^+}^alpha$ are the standard Riemann-Liouville fractional derivative and fractional integral respectively. Some existence and uniqueness results are obtained by applying some standard fixed point principles. Several examples are given to illustrate the results.
On-Line Real-Time Service-Oriented Task Scheduling Using TUF
Shuo Liu,Gang Quan,Shangping Ren
ISRN Software Engineering , 2012, DOI: 10.5402/2012/681985
Abstract:
The Immunoglobulin Superfamily Protein Differentiation of Embryonic Stem Cells 1 (Dies1) Has a Regulatory Role in Preadipocyte to Adipocyte Conversion
Gang Ren, Cameron Beech, Cynthia M. Smas
PLOS ONE , 2013, DOI: 10.1371/journal.pone.0065531
Abstract: Differentiation of Embryonic Stem Cells 1 (Dies1) was recently identified as a novel type I immunoglobulin (IgG) domain-containing plasma membrane protein important for effective differentiation of a murine pluripotent embryonic stem cell line. In this setting, Dies1 enhances bone morphogenetic protein 4 (BMP4) signaling. Here we show Dies1 transcript expression is induced ~225-fold during in vitro adipogenesis of 3T3-L1 murine preadipocytes. Immunocytochemical imaging using ectopic expression of Flag-tagged Dies1 in 3T3-L1 adipocytes revealed localization to the adipocyte plasma membrane. Modulation of adipocyte phenotype with with tumor necrosis factor-α (TNFα) treatment or by siRNA knockdown of the master pro-adipogenic transcription factor peroxisome proliferator activated receptor gamma (PPARγ) resulted in a 90% and 60% reduction of Dies1 transcript levels, respectively. Moreover, siRNA-mediated Dies1 knockdown in 3T3-L1 preadipocytes inhibited adipogenic conversion. Such cultures had a 35% decrease in lipid content and a 45%–65% reduction in expression of key adipocyte transcripts, including that for PPARγ. The standard protocol for full in vitro adipogenic conversion of committed preadipocytes, such as 3T3-L1, does not include BMP4 treatment. Thus we posit the positive role of Dies1 in adipogenesis, unlike that for Dies1 in differentiation of embryonic stem cells, does not include its pro-BMP4 effects. In support of this idea, 3T3-L1 adipocytes knocked down for Dies1 did not evidence decreased phospho-Smad1 levels upon BMP4 exposure. qPCR analysis of Dies1 transcript in multiple murine and human tissues reveals high enrichment in white adipose tissue (WAT). Interestingly, we observed a 10-fold induction of Dies1 transcript in WAT of fasted vs. fed mice, suggesting a role for Dies1 in nutritional response of mature fat cells in vivo. Together our data identify Dies1 as a new differentiation-dependent adipocyte plasma membrane protein whose expression is required for effective adipogenesis and that may also play a role in regard to nutritional status in WAT.
Application of Macrofiber Composite for Smart Transducer of Lamb Wave Inspection
Gang Ren,Kyung-Young Jhang
Advances in Materials Science and Engineering , 2013, DOI: 10.1155/2013/281575
Abstract: Macrofiber composite (MFC) has been developed recently as a new type of smart material for piezoelectric transducers. It shows advantages over traditional piezoelectric ceramic materials (PZT) including the method of application, sensitivity, and cost. It can be embedded on the structure, which provides the possibility to monitor the structural health in real time. In this paper, the feasibility of this transducer for the Lamb wave inspection has been experimentally explored. A pair of MFC patches is bonded on a 2?mm thick aluminum plate, and it has been demonstrated that the dispersive characteristics of S0 and A0 modes, generated and detected by MFC patches, agreed well with the theory. The influence of the bonding condition of the transducer was also tested to show that rigid bonding is required to assure a high amplitude signal. In order to illustrate the performance of defect detection, an artificial defect fabricated on the surface of a specimen was inspected in the pitch-catch mode. The results showed that the MFC transducer is a promising Lamb wave transducer for nondestructive testing (NDT) and structural health monitoring (SHM). 1. Introduction With a view to enhance the safety and reliability in nondestructive evaluation (NDE), the development of highly efficient techniques for nondestructive damage detection or structural health monitoring is of vital significance [1]. Such SHM requires small, lightweight, cheap, and sensitive smart transducers to be embedded on the surface of the structure at affordable cost, especially in the aerospace field. In addition, the traditional PZT is not suitable for this situation because of limitations such as being monolithic, inflexible, and brittle. In order to make up for these limitations, a series of smart material transducers was developed in the past two decades. Piezoelectric films (PVDFs) have been used in SHM system [2–4]. Compared to the traditional PZT transducers, they have some advantages of durability and flexibility, but due to poor electromechanical coupling efficiency, they need greater actuation power in generation and heavy amplification in detection [5]. There are other transducers, including active fiber composites (AFCs) and macrofiber composites (MFCs) developed at NASA Langley Research Center, and these transducers avoid some of the limitations of PVDFs. AFCs and MFCs are composed of thin piezoceramic fibers sandwiched between layers of adhesive, electrodes, and a polyimide film [6]. These types of transducers produce higher force and strain than the typical monolithic piezoceramic
A new Coherent-Entangled state generated by an asymmetric beam splitter and its applications
Xu Ma,Shuangxi Zhang,Gang Ren
Physics , 2009,
Abstract: A new kind of tripartite non-symmetric coordinate coherent-entangled state (TNCCES) $ | \beta,\gamma,x >$ is proposed which exhibits the properties of both coherence and entanglement and makes up a new quantum mechanical representation.We investigate some properties of TNCCES such as completeness and orthogonality which prove it is just a tripartite complete continuous coordinate base. A protocol for generating TNCCES is proposed using asymmetric beam splitter. And in application of TNCCES, we find its corresponding Wigner operator and carry out its marginal distribution form; further a new tripartite entangled squeezed operator is also presented. The multipartite CES and its generation are also disussed.
The Hamburg/ESO R-process Enhanced Star survey (HERES)VII. Thorium abundances in metal-poor stars
Jing Ren,Norbert Christlieb,Gang Zhao
Physics , 2011, DOI: 10.1051/0004-6361/201118241
Abstract: We report thorium abundances for 77 metal-poor stars in the metallicity range of -3.5<[Fe/H]}<-1.0, based on "snapshot" spectra obtained with VLT-UT2/UVES during the HERES Survey. We were able to determine the thorium abundances with better than 1-sigma confidence for 17 stars, while for 60 stars we derived upper limits. For five stars common with previous studies, our results were in good agreement with the literature results. The thorium abundances span a wide range of about 4.0 dex, and scatter exists in the distribution of log(Th/Eu) ratios for lower metallicity stars, supporting previous studies suggesting the r-process is not universal. We derived ages from the log(Th/Eu) ratios for 12 stars, resulting in large scattered ages, and two stars with significant enhancement of Th relative to Eu are found, indicating the "actinide boost" does not seem to be a rare phenomenon and thus highlighting the risk in using log(Th/Eu) to derive stellar ages.
Partial regularity of suitable weak solutions to the multi-dimensional generalized magnetohydrodynamics equations
Wei Ren,Yanqing Wang,Gang Wu
Mathematics , 2015,
Abstract: In this paper, we are concerned with the partial regularity of the suitable weak solutions to the fractional MHD equations in $\mathbb{R}^{n}$ for $n=2,\,3$. In comparison with the work of the 3D fractional Navier-Stokes equations obtained by Tang and Yu in [24, Commun. Math. Phys. 334: 1455--1482, 2015], our results include their endpoint case $\alpha=3/4$ and the external force belongs to more general parabolic Morrey space. Moreover, we prove some interior regularity criteria just via the scaled mixed norm of the velocity for the suitable weak solutions to the fractional MHD equations.
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