5,109 research outputs found
A variable step-size diffusion affine projection algorithm
No full textThis paper presents a new variable step-size diffusion affine projection algorithm (VSS-DAPA) to advance the filter performance of the diffusion affine projection algorithm (DAPA). The proposed VSS strategy is developed for the DAPA, which can solve the distributed estimation problem over diffusion networks well. To obtain the optimal step size reasonably, we seek the update recursion of mean-square deviation (MSD) that is suitable for the DAPA. The step size is optimally given through the minimization for the MSD of the DAPA at each iteration. The derived step size through the MSD minimization improves the filter performance with respect to the convergence and the estimation error in steady state. The results based on simulations demonstrate that the proposed VSS-DAPA performs better than the existing algorithms with a system-identification scenario in diffusion network. Copyright (C) 2015 John Wiley & Sons, Ltd.1110sciescopu
Vascular endothelial growth factor restores delayed tumor progression in tumors depleted of macrophages
No full textGenetic depletion of macrophages in Polyoma Middle T oncoprotein (PyMT)-induced mammary tumors in mice delayed the angiogenic switch and the progression to malignancy. To determine whether vascular endothelial growth factor A (VEGF-A) produced by tumor-associated macrophages regulated the onset of the angiogenic switch, a genetic approach was used to restore expression of VEGF-A into tumors at the benign stages. This stimulated formation of a high-density vessel network and in macrophage-depleted mice, was followed by accelerated tumor progression. The expression of VEGF-A led to a massive infiltration into the tumor of leukocytes that were mostly macrophages. This study suggests that macrophage-produced VEGF regulates malignant progression through stimulating tumor angiogenesis, leukocytic infiltration and tumor cell invasion
Conflicts between and within the sexes in sexual selection: group report
No full textWest-Eberhard MJ, Bradbury JW, Davies NB, et al. Conflicts between and within the sexes in sexual selection: group report. In: Bradbury JW, ed. Sexual selection: testing the alternatives. Life sciences research reports ; 39. Chichester: Wiley; 1987: 180-195
A simplified approach for incorporating thickness stress in the analysis of sheet metal forming using shell elements
No full textA simplified scheme for considering the thickness stress of shell elements induced by contact is presented which improves the accuracy of sheet metal forming analysis. The yield function formulated on the basis of plane stress conditions is modified to incorporate the effect of transverse normal stress induced by contact forces acting on shell elements and return mapping routine is used to update in-plane stresses at each time step. The transverse normal stress distributions in the thickness direction are determined using the analytic solution of the cylindrical tube under the internal pressure. As numerical examples, uni-axial compression, bi-axial tension and bending tests are treated. The problem of cylindrical cup drawing is also calculated. Each result is compared with the results obtained by the analysis using ABAQUS continuum elements. Copyright (C) 2002 John Wiley Sons, Ltd
STUBBED RIGHT-ANGLE H-PLANE WAVE-GUIDE BEND
No full textA stubbed right-angle H-plane waveguide bend is proposed and its solution is obtained in analytic series form. The Fourier sine transform is used in the spectral domain to obtain the transmission and reflection coefficients in fast convergent series forms. The stubbed right-angle H-plane waveguide bend is shown to have better transmission characteristics (wider bandwidth) than the conventional bend without a stub. (C) 1995 John Wiley & Sons, Inc
Analysis of single-layered multiconductor transmission lines using the fourier transform and mode-matching techniques
No full textThe Fourier transform and mode-matching techniques wire applied in the analysis of single-layered multiconductor transmission lines with finite strip thickness. Based on a quasi-static approach, the problem is formulated to obtain simultaneous equations for the modal coefficients of the potential distributions between transmission lines, Residue calculus is applied to represent the potential distributions in convergent series form Analytical closed-form expressions for the self and mutual capacitances are developed. Numerical computations are performed to compare the validity of the proposed with other published data. (C) 2003 Wiley Periodicals. Inc
Dimensioning Internet Protocol Television Video on Demand Services
No full textThe Internet Protocol Television (IPTV) subscription rate has increased steadily since the introduction of IPTV Video on Demand (VoD) services. We have developed a model to determine the optimum deployment strategy for delivering IPTV VoD network services from the IPTV service providers' perspective. The analysis technique in this paper helps us determine how to support a particular IPTV VoD deployment having a given number of customers that each must receive a contracted Quality of Experience (QoE). The main QoE measures considered are server waiting time, one-way minimum delay and access network bandwidth consumption. All these models are made considering heterogeneous network conditions. The QoE models will help service providers make network deployment decisions including the number of servers, distance of servers from a community and desirable access network bandwidth capacity. Copyright (C) 2011 John Wiley & Sons, Ltd.X1122sciescopu
The emerging role of autophagy in the pathophysiology of diabetes mellitus
No full textAn emerging body of evidence supports a role for autophagy in the pathophysiology of type 1 and type 2 diabetes mellitus. Persistent high concentrations of glucose lead to imbalances in the antioxidant capacity within the cell resulting in oxidative stress-mediated injury in both disorders. An anticipated consequence of impaired autophagy is the accumulation of dysfunctional organelles such as mitochondria within the cell. Mitochondria are the primary site of the production of reactive oxygen species (ROS), and an imbalance in ROS production relative to the cytoprotective action of autophagy may lead to the accumulation of ROS. Impaired mitochondrial function associated with increased ROS levels have been proposed as mechanisms contributing to insulin resistance. In this article we review and interpret the literature that implicates a role for autophagy in the pathophysiology of type 1 and type 2 diabetes mellitus as it applies to β-cell dysfunction, and more broadly to organ systems involved in complications of diabetes including the cardiovascular, renal and nervous systems
Anomalously high cooperativity of oligodeoxycytidylic acid for luminescence resonance energy transfer to lanthanide ions
No full textThe luminescence of terbium(III) and europium(III) through luminescence resonance energy transfer from mononucleotides and oligodeoxynucleotides is examined. Among mononucleotides, dGMP gives the strongest luminescence of terbium(III), while dTMP and dCMP yield a luminescence intensity of europium(III) that is larger than the other two cases. In the homodeoxydecamers, decadeoxycytidylic acid (dC(10)) produces the highest intensity for both metals. The anomalously large cooperativity of dC(10) is explained by the easiness of deformation of the helical structure to bind lanthanide ions, and a circular dichroism study supports this explanation. (C) 2002 Wiley Periodicals, Inc.X1144sciescopu
Effects of organoclay modification on microstructure and properties of polypropylene–organoclay nanocomposites
No full textWe prepared polypropylene nanocomposites based on a modified organoclay with isobutyl trimethoxysilane to investigate the effects of such modifications of organoclay on the microstructure and properties of the nanocomposite. The organoclay was preliminarily intercalated with distearyldimethylammonium bromide via an ion exchange before being grafted with silane. The morphology of the polypropylene-organoclay nanocomposites was characterized by wide-angle X-ray diffraction analyses and transmission electron microscopy. The modification of the edges of clay platelets with organic silane resulted in a more uniform dispersion of nonagglomerated tactoids, which consisted of several intercalated clay platelets. However, the unmodified organoclay led to a mixed morphology with both agglomerated and nonagglomerated tactoids. The grafting of the clay edges with organic silane also affected the linear viscoelastic properties of the nanocomposites in the melt state, which was shown to be sensitive to the interaction between the edges of clay platelets as well as to the interaction of the polymer with the platelet edges. (c) 2005 Wiley Periodicals, Inc
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