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Particular Structure (particular + structure)
Selected AbstractsNeuroanatomical substrates of social cognition dysfunction in autismDEVELOPMENTAL DISABILITIES RESEARCH REVIEW, Issue 4 2004Kevin Pelphrey Abstract In this review article, we summarize recent progress toward understanding the neural structures and circuitry underlying dysfunctional social cognition in autism. We review selected studies from the growing literature that has used the functional neuroimaging techniques of cognitive neuroscience to map out the neuroanatomical substrates of social cognition in autism. We also draw upon functional neuroimaging studies with neurologically normal individuals and individuals with brain lesions to highlight the insights these studies offer that may help elucidate the search for the neural basis of social cognition deficits in autism. We organize this review around key brain structures that have been implicated in the social cognition deficits in autism: (1) the amygdala, (2) the superior temporal sulcus region, and (3) the fusiform gyrus. We review some of what is known about the contribution of each structure to social cognition and then review autism studies that implicate that particular structure. We conclude with a discussion of several potential future directions in the cognitive neuroscience of social deficits in autism. © 2004 Wiley-Liss, Inc. MRDD Research Reviews 2004;10:259,271. [source] The role of soil in the collapse of 18 piers of Hanshin Expressway in the Kobe earthquakeEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2006George Mylonakis Abstract An investigation is presented of the collapse of a 630 m segment (Fukae section) of the elevated Hanshin Expressway during the 1995 Kobe earthquake. The earthquake has, from a geotechnical viewpoint, been associated with extensive liquefactions, lateral soil spreading, and damage to waterfront structures. Evidence is presented that soil,structure interaction (SSI) in non-liquefied ground played a detrimental role in the seismic performance of this major structure. The bridge consisted of single circular concrete piers monolithically connected to a concrete deck, founded on groups of 17 piles in layers of loose to dense sands and moderate to stiff clays. There were 18 spans in total, all of which suffered a spectacular pier failure and transverse overturning. Several factors associated with poor structural design have already been identified. The scope of this work is to extend the previous studies by investigating the role of soil in the collapse. The following issues are examined: (1) seismological and geotechnical information pertaining to the site; (2) free-field soil response; (3) response of foundation-superstructure system; (4) evaluation of results against earlier studies that did not consider SSI. Results indicate that the role of soil in the collapse was multiple: First, it modified the bedrock motion so that the frequency content of the resulting surface motion became disadvantageous for the particular structure. Second, the compliance of soil and foundation altered the vibrational characteristics of the bridge and moved it to a region of stronger response. Third, the compliance of the foundation increased the participation of the fundamental mode of the structure, inducing stronger response. It is shown that the increase in inelastic seismic demand in the piers may have exceeded 100% in comparison with piers fixed at the base. These conclusions contradict a widespread view of an always-beneficial role of seismic SSI. Copyright © 2005 John Wiley & Sons, Ltd. [source] An eigenvector-based linear reconstruction scheme for the shallow-water equations on two-dimensional unstructured meshesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 1 2007Sandra Soares Frazão Abstract This paper presents a new approach to MUSCL reconstruction for solving the shallow-water equations on two-dimensional unstructured meshes. The approach takes advantage of the particular structure of the shallow-water equations. Indeed, their hyperbolic nature allows the flow variables to be expressed as a linear combination of the eigenvectors of the system. The particularity of the shallow-water equations is that the coefficients of this combination only depend upon the water depth. Reconstructing only the water depth with second-order accuracy and using only a first-order reconstruction for the flow velocity proves to be as accurate as the classical MUSCL approach. The method also appears to be more robust in cases with very strong depth gradients such as the propagation of a wave on a dry bed. Since only one reconstruction is needed (against three reconstructions in the MUSCL approach) the EVR method is shown to be 1.4,5 times as fast as the classical MUSCL scheme, depending on the computational application. Copyright © 2006 John Wiley & Sons, Ltd. [source] Application of nonlinear time,scaling for robust controller design of reaction systemsINTERNATIONAL JOURNAL OF ROBUST AND NONLINEAR CONTROL, Issue 1 2002P. Moya Abstract Even though the basic mechanisms of operation of reaction systems are relatively simple the dynamical models obtained from first principles are complex and contain highly uncertain terms. To develop reliable model-based controllers it is therefore necessary to simplify the system dynamics preserving the features which are essential for control. Towards this end, co-ordinate transformations identifying the states which are dependent/independent of the reactions and flows have been reported in the literature. This has allowed, for instance, the design of observers which are insensitive to the (usually unknown) reaction functions. The main contribution of this paper is to show the utility of nonlinear state-dependent time-scaling to simplify the system dynamics, and consequently the controller design. In particular, we show that with time-scaling and an input transformation we can reveal the existence of attractive invariant manifolds, which allows us to reduce the dimension of the system. As an application we study the well-known fourth order baker's yeast fed-batch fermentation process model, whose essential dynamics is captured by a planar system perturbed by an exponentially decaying term. We then exploit this particular structure to design, with reduced control authority, a nonlinear asymptotically stabilizing control law which is robust with respect to the reaction function. Copyright © 2001 John Wiley & Sons, Ltd. [source] Morphology prediction of ternary polypropylene composites containing elastomer and calcium carbonate nanoparticles fillerJOURNAL OF APPLIED POLYMER SCIENCE, Issue 3 2007C. G. Ma Abstract In this work, the morphology was studied in ternary composites of polypropylene (PP) with nanosized calcium carbonate (nano-CaCO3) fillers and elastomer inclusions and the thermodynamic consideration was used to analyze the formation of phase structure of the composites. The wetting coefficient (,a), interfacial tension (,AB), and work of adhesion (WAB) were calculated to predict dispersion state of nano-CaCO3 fillers. A comparison of the prediction and SEM analysis was given. The results show that three types of phase structures were formed: an encapsulation of the filler by elastomer, a separate dispersion of the filler and elastomer, and a particular structure of the filler at the PP/elastomer interface. The predictions by ,a were all successfully supported-up by SEM analysis and the predictions by WAB were however trustless. Both ,AB and WAB can predict a separate dispersion or an encapsulation phase structure, but they were not available for the particular structure of the filler at the PP/elastomer interface. ,a was competent and favored for the prediction of all three types of morphology among the three parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 1578,1584, 2007 [source] Computational alanine scanning of the 1:1 human growth hormone,receptor complexJOURNAL OF COMPUTATIONAL CHEMISTRY, Issue 1 2002Shuanghong Huo Abstract The MM-PBSA (Molecular Mechanics,Poisson,Boltzmann surface area) method was applied to the human Growth Hormone (hGH) complexed with its receptor to assess both the validity and the limitations of the computational alanine scanning approach. A 400-ps dynamical trajectory of the fully solvated complex was simulated at 300 K in a 101 Å×81 Å×107 Å water box using periodic boundary conditions. Long-range electrostatic interactions were treated with the particle mesh Ewald (PME) summation method. Equally spaced snapshots along the trajectory were chosen to compute the binding free energy using a continuum solvation model to calculate the electrostatic desolvation free energy and a solvent-accessible surface area approach to treat the nonpolar solvation free energy. Computational alanine scanning was performed on the same set of snapshots by mutating the residues in the structural epitope of the hormone and the receptor to alanine and recomputing the ,Gbinding. To further investigate a particular structure, a 200-ps dynamical trajectory of an R43A hormone,receptor complex was simulated. By postprocessing a single trajectory of the wild-type complex, the average unsigned error of our calculated ,,Gbinding is ,1 kcal/mol for the alanine mutations of hydrophobic residues and polar/charged residues without buried salt bridges. When residues involved in buried salt bridges are mutated to alanine, it is demonstrated that a separate trajectory of the alanine mutant complex can lead to reasonable agreement with experimental results. Our approach can be extended to rapid screening of a variety of possible modifications to binding sites. © 2002 Wiley Periodicals, Inc. J Comput Chem 23: 15,27, 2002 [source] Soft Langmuir,Blodgett Technique for Hard NanomaterialsADVANCED MATERIALS, Issue 29 2009Somobrata Acharya Abstract Materials and their assemblies of dimensions down to a few nanometers have attracted considerable scientific interest in physical, chemical, and biological sciences because of unique properties not available in their bulk counterparts. The Langmuir,Blodgett (LB) technique allows rigid nanomaterials to be aligned in particular structures through a flexible assembly process at liquid interfaces. In this review, we summarize the development of assembly of hard nanomaterials using soft LB techniques. An initial summary of the basic features of nanomaterials will include dimension-related effects, synthesis, characterization, and analysis, and will be followed by examples of LB assemblies of nanomaterials described according to their morphology: nanoparticles, nanorods, nanowires, nanotubes, and nanosheets. Some of the nanomaterials have been fabricated in orientation-controlled morphologies, and have been incorporated into prototype devices for gas sensing and photocurrent transport. In the final part of this review, the challenges remaining for LB techniques of hard nanomaterials will be overviewed, and will include a comparison with the widely-used LB technique involving soft materials. [source] | |||||||||||||