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Search Results: 1 - 10 of 266871 matches for " D. Chen "
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A Legacy System Encapsulation Strategy Based on Web Service  [PDF]
D. J. Chen, X. Y. Li
Creative Education (CE) , 2012, DOI: 10.4236/ce.2012.37B014
Abstract:

In order to migrate the enterprise legacy system to the web, a multi-agent based legacy system encapsulation model is proposed.  Firstly, the characteristics of legacy system are analyzed, and then the data and functions that need to be published are confirmed. Secondly the legacy system is wrapped into web components with common interface, and these components are managed by the application server. Thirdly, the clients can send requests to the application server, and receive the return result from the application server.  Due to adoption of wrapping technology for legacy system, original security and stability of legacy system are guaranteed in the web components. Finally, the validity and practicability of the migration technology are verified through the application in the encapsulation of Matlab as web components.

Heterogeneous Economic Impacts of Transportation Features on Prefecture-Level Chinese Cities  [PDF]
Bismark R. D. K. Agbelie, Yang Chen, Nimesh Salike
Theoretical Economics Letters (TEL) , 2017, DOI: 10.4236/tel.2017.73026
Abstract: The present paper examines the heterogeneous economic impacts of transportation characteristics, with a consideration of spatial heterogeneity, across Chinese prefecture-level cities. Using data from 237 Chinese cities from 2000 to 2012, a random-parameters model is applied to account for the heterogeneity across these cities. The estimation results reveal significant variability across cities, with the computed impacts (elasticity values) of transportation-related features (highway and railway freight volumes, highway passenger volume, urbanization rate, public transit, paved roads, and highway congestion rate) varying significantly across cities. The impacts are mostly positive, except for highway congestion rate. A 1% increase in a city’s highway and railway freight volumes would increase the city’s gross product per capita from 0.0001% to 0.0972% and 0.0001% to 0.0254% across cities in China, respectively. While a 1% increase in highway congestion rate would decrease the city’s gross product per capita by an average of 0.031%.
A New Framework of Multiphase Segmentation and Its Application to Partial Volume Segmentation
Fuhua Chen,Yunmei Chen,Hemant D. Tagare
Applied Computational Intelligence and Soft Computing , 2011, DOI: 10.1155/2011/786369
Abstract: We proposed a novel framework of multiphase segmentation based on stochastic theory and phase transition theory. Our main contribution lies in the introduction of a constructed function so that its composition with phase function forms membership functions. In this way, it saves memory space and also avoids the general simplex constraint problem for soft segmentations. The framework is then applied to partial volume segmentation. Although the partial volume segmentation in this paper is focused on brain MR image, the proposed framework can be applied to any segmentation containing partial volume caused by limited resolution and overlapping.
Resonant Interactions in Rotating Homogeneous Three-dimensional Turbulence
Q. Chen,S. Chen,G. L. Eyink,D. D. Holm
Physics , 2004, DOI: 10.1017/S0022112005006324
Abstract: Direct numerical simulations of three-dimensional (3D) homogeneous turbulence under rapid rigid rotation are conducted to examine the predictions of resonant wave theory for both small Rossby number and large Reynolds number. The simulation results reveal that there is a clear inverse energy cascade to the large scales, as predicted by 2D Navier-Stokes equations for resonant interactions of slow modes. As the rotation rate increases, the vertically-averaged horizontal velocity field from 3D Navier-Stokes converges to the velocity field from 2D Navier-Stokes, as measured by the energy in their difference field. Likewise, the vertically-averaged vertical velocity from 3D Navier-Stokes converges to a solution of the 2D passive scalar equation. The energy flux directly into small wave numbers in the $k_z=0$ plane from non-resonant interactions decreases, while fast-mode energy concentrates closer to that plane. The simulations are consistent with an increasingly dominant role of resonant triads for more rapid rotation.
Design Principles for Ligand-Sensing, Conformation-Switching Ribozymes
Xi Chen,Andrew D. Ellington
PLOS Computational Biology , 2009, DOI: 10.1371/journal.pcbi.1000620
Abstract: Nucleic acid sensor elements are proving increasingly useful in biotechnology and biomedical applications. A number of ligand-sensing, conformational-switching ribozymes (also known as allosteric ribozymes or aptazymes) have been generated by some combination of directed evolution or rational design. Such sensor elements typically fuse a molecular recognition domain (aptamer) with a catalytic signal generator (ribozyme). Although the rational design of aptazymes has begun to be explored, the relationships between the thermodynamics of aptazyme conformational changes and aptazyme performance in vitro and in vivo have not been examined in a quantitative framework. We have therefore developed a quantitative and predictive model for aptazymes as biosensors in vitro and as riboswitches in vivo. In the process, we have identified key relationships (or dimensionless parameters) that dictate aptazyme performance, and in consequence, established equations for precisely engineering aptazyme function. In particular, our analysis quantifies the intrinsic trade-off between ligand sensitivity and the dynamic range of activity. We were also able to determine how in vivo parameters, such as mRNA degradation rates, impact the design and function of aptazymes when used as riboswitches. Using this theoretical framework we were able to achieve quantitative agreement between our models and published data. In consequence, we are able to suggest experimental guidelines for quantitatively predicting the performance of aptazyme-based riboswitches. By identifying factors that limit the performance of previously published systems we were able to generate immediately testable hypotheses for their improvement. The robust theoretical framework and identified optimization parameters should now enable the precision design of aptazymes for biotechnological and clinical applications.
Heparanase Regulates Levels of Syndecan-1 in the Nucleus
Ligong Chen, Ralph D. Sanderson
PLOS ONE , 2009, DOI: 10.1371/journal.pone.0004947
Abstract: Syndecan-1 is a transmembrane heparan sulfate-bearing proteoglycan known to regulate multiple biological functions at the cell surface and within the extracellular matrix. Its functional activity can be modulated by heparanase, an enzyme that cleaves heparan sulfate chains and whose expression has been associated with an aggressive phenotype in many cancers. In addition to remodeling syndecan-1 by cleaving its heparan sulfate chains, heparanase influences syndecan-1 location by upregulating expression of enzymes that accelerate its shedding from the cell surface. In the present study we discovered that heparanase also alters the level of nuclear syndecan-1. Upon upregulation of heparanase expression or following addition of recombinant heparanase to myeloma cells, the nuclear localization of syndecan-1 drops dramatically as revealed by confocal microscopy, western blotting and quantification by ELISA. This effect requires enzymatically active heparanase because cells expressing high levels of mutated, enzymatically inactive heparanase, failed to diminish syndecan-1 levels in the nucleus. Although heparan sulfate function within the nucleus is not well understood, there is emerging evidence that it may act to repress transcriptional activity. The resulting changes in gene expression facilitated by the loss of nuclear syndecan-1 could explain how heparanase enhances expression of MMP-9, VEGF, tissue factor and perhaps other effectors that condition the tumor microenvironment to promote an aggressive cancer phenotype.
Comparative Analysis of E2F Family Member Oncogenic Activity
Chunxia Chen, Andrew D. Wells
PLOS ONE , 2007, DOI: 10.1371/journal.pone.0000912
Abstract: The E2F family of transcription factors consists of nine members with both distinct and overlapping functions. These factors are situated downstream of growth factor signaling cascades, where they play a central role in cell growth and proliferation through their ability to regulate genes involved in cell cycle progression. For this reason, it is likely that the members of the E2F family play a critical role during oncogenesis. Consistent with this idea is the observation that some tumors exhibit deregulated expression of E2F proteins. In order to systematically compare the oncogenic capacity of these family members, we stably over-expressed E2F1 through 6 in non-transformed 3T3 fibroblasts and assessed the ability of these transgenic cell lines to grow under conditions of low serum, as well as to form colonies in soft agar. Our results show that these six E2F family members can be divided into three groups that exhibit differential oncogenic capacity. The first group consists of E2F2 and E2F3a, both of which have strong oncogenic capacity. The second group consists of E2F1 and E2F6, which were neutral in our assays when compared to control cells transduced with vector alone. The third group consists of E2F4 and E2F5, which generally act to repress E2F-responsive genes, and in our assays demonstrated a strong capacity to inhibit transformation. Our results imply that the pattern of expression of these six E2F family members in a cell could exert a strong influence over its susceptibility to oncogenic transformation.
Identification of common genetic modifiers of neurodegenerative diseases from an integrative analysis of diverse genetic screens in model organisms
Xi Chen, Robert D Burgoyne
BMC Genomics , 2012, DOI: 10.1186/1471-2164-13-71
Abstract: We carried out an integrated analysis using C. elegans as the baseline model organism since this is the most widely studied in this context. Combination of data from 28 published studies using small to large scale screens in all three small model organisms gave a total of 950 identifications of genetic regulators. Of these 624 were separate genes with orthologues in C. elegans. In addition, 34 of these genes, which all had human orthologues, were found to overlap across studies. Of the common genetic regulators some such as chaperones, ubiquitin-related enzymes (including the E3 ligase CHIP which directly links the two pathways) and histone deacetylases were involved in expected pathways whereas others such as the peroxisomal acyl CoA-oxidase suggest novel targets for neurodegenerative disease therapyWe identified a significant number of overlapping regulators of neurodegenerative disease models. Since the diseases have, as an underlying feature, protein aggregation phenotypes it was not surprising that some of the overlapping genes encode proteins involved in protein folding and protein degradation. Interestingly, however, some of the overlapping genes encode proteins that have not previously featured in targeted studies of neurodegeneration and this information will form a useful resource to be exploited in further studies of potential drug-targets.Despite major advances, debilitating neurodegenerative diseases including Alzheimer's disease (AD), Parkinson's disease (PD), and polyglutamine (polyQ) diseases as exemplified by Huntington's disease (HD) and related ataxias afflict millions worldwide and remains a significant and unresolved burden facing ageing populations. Many genetic factors including specific causative mutations have been identified but therapies for these debilitating and eventually fatal disorders are lacking. These disorders are associated with the unifying theme of accumulation of toxic, misfolded protein aggregates or inclusion bodies followed
Mechanically-evoked C-fiber activity in painful alcohol and AIDS therapy neuropathy in the rat
Xiaojie Chen, Jon D Levine
Molecular Pain , 2007, DOI: 10.1186/1744-8069-3-5
Abstract: The second messenger signaling pathways in primary afferent nociceptors that mediate hypersensitivity to mechanical stimuli differ between models of painful peripheral neuropathies [1]. Two extreme examples of this are the neuropathies induced by chronic ethanol consumption, and by acquired immunodeficiency disease syndrome (AIDS) therapy (nucleoside reverse transcriptase inhibitors). In alcohol-induced neuropathy, protein kinase Cε(PKCε) has a major contribution to mechanical hyperalgesia [2], whereas in AIDS therapy neuropathy, Ca++, caspase signaling and mitochondrial electron transport [3-5] but not PKCε or a number of other second messenger signaling pathways (i.e., protein kinase A, protein kinase G, extracellular signal-regulated kinases 1/2 or nitric oxide) contribute [3].Enhanced activity in sensory neurons is thought to contribute to pain reported by patients with small-fiber peripheral neuropathies. Microneurography techniques have demonstrated pathological responses such as sensitization to mechanical stimuli, in patients with trigeminal neuralgia [6], traumatic nerve injury [7], entrapment neuropathy [8], phantom limb [9] and erythromelalgia [10]. However, there are practical limitations in performing microneurography in patients, including inability to classify fiber functions fully, small numbers of fibers that can be evaluated in an individual patient and the potential for inducing further injury by introducing a microelectrode into an already damaged nerve. Furthermore, in spite of the fact that in most patients, metabolic abnormalities, toxins, drugs or infectious organisms are producing the neuropathic conditions, most microneurography studies have been done in patients with a traumatic nerve injury [7-9].Single-fiber electrophysiology has been performed in animal models of metabolic and toxic, as well as traumatic nerve injury-associated painful peripheral neuropathy. Following traumatic nerve injury it has been reported that there is increased s
A broadband optical cavity spectrometer for measuring weak near-ultraviolet absorption spectra of gases
J. Chen ,D. S. Venables
Atmospheric Measurement Techniques (AMT) & Discussions (AMTD) , 2011,
Abstract: Accurate absorption spectra of gases in the near–ultraviolet (300 to 400 nm) are essential in atmospheric observations and laboratory studies. This paper describes a novel incoherent broadband cavity-enhanced absorption spectroscopy (IBBCEAS) instrument for measuring very weak absorption spectra from 335 to 375 nm. The instrument performance was validated against the 3B1-X1A1 transition of SO2. The measured absorption varied linearly with SO2 column density and the resulting spectrum agrees well with published spectra. Using the instrument, we report new absorption cross-sections of O3, acetone, 2-butanone, and 2-pentanone in this spectral region, where literature data diverge considerably. In the absorption minimum between the Huggins and Chappuis bands, our absorption spectra fall at the lower range of reported ozone absorption cross-sections. The spectra of the ketones agree with prior spectra at moderate absorptions, but differ significantly at the limits of other instruments' sensitivity. The collision-induced absorption of the O4 dimer at 360.5 nm was also measured and found to have a maximum cross-section of ca. 4.0×10 46 cm5 molecule 2. We demonstrate the application of the instrument to quantifying low concentrations of the short-lived radical, BrO, in the presence of stronger absorptions from Br2 and O3.
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