Home About us Contact
|
Home About us Contact | ||
|
|
||
Singular
Terms modified by Singular Selected AbstractsPose Optimization of Serial Manipulators Using Knowledge of Their Velocity-Degenerate (Singular) ConfigurationsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2003Scott B. Nokleby This work investigates the exploitation of velocity-degenerate configurations to optimize the pose of either nonredundant or redundant serial manipulators to sustain desired wrenches. An algorithm is developed that determines a desirable start point for the optimization of a serial manipulator's pose. The start-point algorithm (SPA) uses analytical expressions of the velocity-degenerate (singular) configurations of a serial manipulator to determine a pose that would be best suitable to sustain a desired wrench. Results for an example redundant serial manipulator are presented. The example results show that by using the SPA with the optimization routine, the resulting poses obtained require less effort from the actuators when compared to the poses obtained without using the SPA. It is shown that when no constraint is imposed on the position of the end-effector, the SPA excels at providing a better solution with less iterations than running the optimization without the SPA. © 2003 Wiley Periodicals, Inc. [source] A Philosophy of the First-Person Singular,COMMUNICATION THEORY, Issue 1 2007Vincent Descombes According to Emile Benveniste, there are only 2 grammatical persons (the first and the second) because being a grammatical person is a matter of taking part actively in a dialogical act of speech. The so-called third person should rather be called the nonperson, the "absent" of the dialogue. Paul Ricoeur has questioned this interpretation of the third person in so far as it meets a philosophical dogma once maintained by Jean-Paul Sartre in his theory of the novel. Sartre claimed that the author of a novel, when introducing a character into the narrative, should choose between the first-person point of view and the third-person one. Ricoeur has rightly argued that this was not the case, as it is obviously possible to use the grammatical third person in order to present the personal thoughts and feelings of somebody else. If one could not do that, it would not be possible to consider "oneself as another." [source] Wavelet Packet-Autocorrelation Function Method for Traffic Flow Pattern AnalysisCOMPUTER-AIDED CIVIL AND INFRASTRUCTURE ENGINEERING, Issue 5 2004Xiaomo Jiang A detailed understanding of the properties of traffic flow is essential for building a reliable forecasting model. The discrete wavelet packet transform (DWPT) provides more coefficients than the conventional discrete wavelet transform (DWT), representing additional subtle details of a signal. In wavelet multiresolution analysis, an important decision is the selection of the decomposition level. In this research, the statistical autocorrelation function (ACF) is proposed for the selection of the decomposition level in wavelet multiresolution analysis of traffic flow time series. A hybrid wavelet packet-ACF method is proposed for analysis of traffic flow time series and determining its self-similar, singular, and fractal properties. A DWPT-based approach combined with a wavelet coefficients penalization scheme and soft thresholding is presented for denoising the traffic flow. The proposed methodology provides a powerful tool in removing the noise and identifying singularities in the traffic flow. The methods created in this research are of value in developing accurate traffic-forecasting models. [source] Field simultaneous measurements, modeling, and simulation of harmonic components in a small generation-transmission networkEUROPEAN TRANSACTIONS ON ELECTRICAL POWER, Issue 1 2007S. Ríos M Abstract This paper presents a detailed deterministic model for a small electrical transmission network (110,kV), representing a large (150,MVA) industrial Copper mine production plant. This model is developed and validated with simultaneous field measurements. The network topology allows two operating modes, ring and open ring operation, without disturbing the busbar loads. Experimental results of,simultaneous,measurements at the three load busbars confirm the simulation results obtained with a state space deterministic model. A sensitivity assessment of busbar harmonic distortions, based on singular and eigenvalues analysis, is also presented. Copyright © 2006 John Wiley & Sons, Ltd. [source] Structural and functional evidence for a singular repertoire of BMP receptor signal transducing proteins in the lophotrochozoan Crassostrea gigas suggests a shared ancestral BMP/activin pathwayFEBS JOURNAL, Issue 13 2005Amaury Herpin The transforming growth factor , (TGF-,) superfamily includes bone morphogenetic proteins, activins and TGF-,sensu stricto (s.s). These ligands, which transduce their signal through a heteromeric complex of type I and type II receptors, have been shown to play a key role in numerous biological processes including early embryonic development in both deuterostomes and ecdyzozoans. Lophochotrozoans, the third major group of bilaterian animals, have remained in the background of the molecular survey of metazoan development. We report the cloning and functional study of the central part of the BMP pathway machinery in the bivalve mollusc Crassostrea gigas (Cg- BMPR1 type I receptor and Cg- TGF,sfR2 type II receptor), showing an unusual functional mode of signal transduction for this superfamily. The use of the zebrafish embryo as a reporter organism revealed that Cg- BMPR1, Cg- TGF,sfR2, Cg- ALR I, an activin Type I receptor or their dominant negative acting truncated forms, when overexpressed during gastrulation, resulted in a range of phenotypes displaying severe disturbance of anterioposterior patterning, due to strong modulations of ventrolateral mesoderm patterning. The results suggest that Cg- BMPR1, and to a certain degree Cg- TGF,sfR2 proteins, function in C. gigas in a similar way to their zebrafish orthologues. Finally, based on phylogenetic analyses, we propose an evolutionary model within the complete TGF-, superfamily. Thus, evidence provided by this study argues for a possible conserved endomesoderm/ectomesoderm inductive mechanism in spiralians through an ancestral BMP/activin pathway in which the singular, promiscuous and probably unique Cg- TGF,sfR2 would be the shared type II receptor interface for both BMP and activin ligands. [source] Properties of 2,2,2-Trifluoroethanol/Water Mixtures: Acidity, Basicity, and DipolarityHELVETICA CHIMICA ACTA, Issue 2 2005Paz Sevilla, Sierra In this report, we focus our attention on the characterization of 2,2,2-trifluoroethanol(TFE)/H2O mixtures and describe their intrinsic parameters; i.e., solvent acidity (SA), solvent basicity (SB), and solvent dipolarity/polarizability (SPP), by the probe/homomorph-couple method for a range of mixtures from 0,100% (v/v) TFE. Variation of these parameters is not linear and has a singular and unpredictable behavior depending on the precise composition of the mixture. Based on these parameters, we describe the TFE-induced changes in some physical properties; i.e., viscosity (,), partial molar volume (V,), density (,), dielectric constant (,), vapor pressure (pv), and spectroscopic properties; i.e., NMR chemical shifts (,(1H)) of TFE Me group for all molar fractions studied. In addition, by means of CD studies, we report that formation of the secondary structure, as percentage of helical content, ,, of a polypeptide, poly(L -lysine), in several TFE/H2O mixtures is adequately described by these mixture parameters. SA, SB, and SPP of TFE/H2O mixtures provide an excellent tool for the interpretation of formation and stability of intramolecular H-bonds, and, thus, of secondary structures in polypeptides. [source] Reflections on Retelling a Renaissance MurderHISTORY AND THEORY, Issue 4 2002Thomas V. Cohen This mischievously artful essay plays out on several levels; think of them as storeys of an imaginary castle much like the real, solid, central Italian one it explores and expounds. On its own ground floor, the essay recounts a gruesome murder, a noble husband's midnight revenge upon his wife and upon her bastard lover, his own half,brother, in her castle chamber, in bed. In sex. Of course. The murder itself is pure Renaissance, quintessential Boccaccio or Bandello, but the aftermath, in fort and village, is more singular, more ethnographically delightful, as castle and village trace a ceremonious passage from frozen limbo to fluid grief and storytelling, finally set in motion by the arrival of the dead wife's brother. Meanwhile, one flight up, the essay retells my own investigation of the real castle's geometry, as I clambered through rooms, peered out windows, prowled the roof, and scanned blueprints seeking the places of the plotters' plots. In an expository attic, I lodge reflections on my teaching stratagems, as I led a first,year seminar into detection's crafts and exposition's ploys. All the while, on its rooftop, this essay dances among fantastical chimneys and turrets of high theory and literary practice, musing on the patent irony of artful artifice, which evokes both the irony and the pathos of scholars' cool histories about hot deeds and feelings. Art suggests we authors had best hide ourselves, unlike normal essayists, so as not to spoil the show. But, I posit, our self,effacement is so conspicuous that it proclaims our presence, as in fact it should, and, by so doing, trumpets the necessary tensions of our artifice and craft. Thus artfulness itself nicely both proclaims and celebrates the bittersweet frustrations of historians' and readers' quest for knowledge and, especially, for experience of a lost past. [source] Self-references among children's first fifty words: Indications for an emerging sense of self in Dutch-speaking childrenINFANT AND CHILD DEVELOPMENT, Issue 4 2001Matty van der Meulen Abstract The present study investigated at what age self-references would turn up for the first time in young children's language and what kind of words these were. This was studied for a corpus of the first 50 words, produced by ten children, five boys and five girls, collected through parental reports. Self-references were defined as all words that referred in one way or another to the speakers themselves. They were not restricted to utterances containing pronominals of the first person singular or the child's first name. The appearance of self-references varied with the onset of speech. Children who started to speak early also produced self-referent words at an early age (between 12 and 16 months). Self-references could be satisfactorily classified into three lexical categories: nominals, action words and modifiers, containing words (a) labelling body parts, (b) verbalizing action plans and ongoing actions, and (c) expressing characteristics of outer appearance and actions, and physical sensations, respectively. This indicates that young children's sense of self is not restricted to an awareness of their own actions, but that a variety of experiences contribute to this. Copyright © 2001 John Wiley & Sons, Ltd. [source] Semi-analytical elastostatic analysis of unbounded two-dimensional domainsINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 11 2002Andrew J. Deeks Abstract Unbounded plane stress and plane strain domains subjected to static loading undergo infinite displacements, even when the zero displacement boundary condition at infinity is enforced. However, the stress and strain fields are well behaved, and are of practical interest. This causes significant difficulty when analysis is attempted using displacement-based numerical methods, such as the finite-element method. To circumvent this difficulty problems of this nature are often changed subtly before analysis to limit the displacements to finite values. Such a process is unsatisfactory, as it distorts the solution in some way, and may lead to a stiffness matrix that is nearly singular. In this paper, the semi-analytical scaled boundary finite-element method is extended to permit the analysis of such problems without requiring any modification of the problem itself. This is possible because the governing differential equations are solved analytically in the radial direction. The displacement solutions so obtained include an infinite component, but relative motion between any two points in the unbounded domain can be computed accurately. No small arbitrary constants are introduced, no arbitrary truncation of the domain is performed, and no ill-conditioned matrices are inverted. Copyright © 2002 John Wiley & Sons, Ltd. [source] Acoustic eigenanalysis for multiply-connected problems using dual BEMINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN BIOMEDICAL ENGINEERING, Issue 6 2004J. T. Chen Abstract In this paper, the eigenanalysis for the multiply-connected domain problem is studied by using the dual boundary element method. The occurrence and treatment of the spurious eigenvalues for multiply-connected domain problem are reviewed when the complex-valued BEM in used. Three approaches, Burton and Miller method, CHIEF concept and SVD updating techniques, are adopted to suppress the occurrence of spurious eigensolutions. Instead of using the singular and hypersingular formulations, the singularity-free methods, the null-field equation approach and the fictitious BEM, are also utilized to deal with the eigenproblem. Both the eigenvalues and eigenmodes are compared with the analytical solutions and those of FEM for the illustrative examples. Good agreement is made. Copyright © 2004 John Wiley & Sons, Ltd. [source] A hypersingular time-domain BEM for 2D dynamic crack analysis in anisotropic solidsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 2 2009M. Wünsche Abstract A hypersingular time-domain boundary element method (BEM) for transient elastodynamic crack analysis in two-dimensional (2D), homogeneous, anisotropic, and linear elastic solids is presented in this paper. Stationary cracks in both infinite and finite anisotropic solids under impact loading are investigated. On the external boundary of the cracked solid the classical displacement boundary integral equations (BIEs) are used, while the hypersingular traction BIEs are applied to the crack-faces. The temporal discretization is performed by a collocation method, while a Galerkin method is implemented for the spatial discretization. Both temporal and spatial integrations are carried out analytically. Special analytical techniques are developed to directly compute strongly singular and hypersingular integrals. Only the line integrals over an unit circle arising in the elastodynamic fundamental solutions need to be computed numerically by standard Gaussian quadrature. An explicit time-stepping scheme is obtained to compute the unknown boundary data including the crack-opening-displacements (CODs). Special crack-tip elements are adopted to ensure a direct and an accurate computation of the elastodynamic stress intensity factors from the CODs. Several numerical examples are given to show the accuracy and the efficiency of the present hypersingular time-domain BEM. Copyright © 2008 John Wiley & Sons, Ltd. [source] Explicit expressions for 3D boundary integrals in potential theory,INTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 1 2009S. Nintcheu Fata Abstract On employing isoparametric, piecewise linear shape functions over a flat triangular domain, exact expressions are derived for all surface potentials involved in the numerical solution of three-dimensional singular and hyper-singular boundary integral equations of potential theory. These formulae, which are valid for an arbitrary source point in space, are represented as analytic expressions over the edges of the integration triangle. They can be used to solve integral equations defined on polygonal boundaries via the collocation method or may be utilized as analytic expressions for the inner integrals in the Galerkin technique. In addition, the constant element approximation can be directly obtained with no extra effort. Sample problems solved by the collocation boundary element method for the Laplace equation are included to validate the proposed formulae. Published in 2008 by John Wiley & Sons, Ltd. [source] On the inverse of generalized ,-matrices with singular leading termINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 4 2006N. A. Dumont Abstract An algorithm is introduced for the inverse of a ,-matrix given as the truncated series A0,i,A1,,2A2+i,3A3+,4A4+···+O(,n+1) with square coefficient matrices and singular leading term A0. Moreover, A1 may be conditionally singular and no restrictions are made for the remaining terms. The result is a ,-matrix given as a unique, truncated series of the same error order. Motivation for this problem is the evaluation of the frequency-dependent stiffness matrix of general boundary or macro-finite elements in the frame of a hybrid variational formulation that is based on a flexibility matrix F expressed as a truncated power series of the circular frequency ,. Copyright © 2005 John Wiley & Sons, Ltd. [source] A conservative integral for bimaterial notches subjected to thermal stressesINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 6 2004Leslie Banks-Sills Abstract In this investigation, a conservative integral based on the Betti reciprocal principle is developed to obtain stress intensity factors for a bimaterial notch in which the body is subjected to a thermal load. The bonded materials are linear elastic, isotropic and homogeneous. According to the linear theory of elasticity, stresses in the neighbourhood of the notch tip are generally singular as a result of the mismatch of the elastic constants. Eigenvalues and eigenfunctions depend upon the mechanical properties and wedge angles. They may be real, complex or power-logarithmic. Real and complex eigenvalues are considered in this study. The stress intensity factor represents the amplitude of the stress singularity and depends upon material properties, geometry and load or temperature. Because of the highly singular behaviour of one of the integrals that is part of the conservative integral, the former is carried out by a hybrid analytical/numerical scheme. The finite element method is employed to obtain displacements caused by the temperature distribution in the body. The conservative integral is applied to several problems appearing in the literature. Both good agreement between those results and the ones obtained here, as well as path stability for all problems is attained. A wide range of material parameters is also studied. Copyright © 2004 John Wiley & Sons, Ltd. [source] A fast boundary cloud method for 3D exterior electrostatic analysisINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 15 2004Vaishali Shrivastava Abstract An accelerated boundary cloud method (BCM) for boundary-only analysis of 3D electrostatic problems is presented here. BCM uses scattered points unlike the classical boundary element method (BEM) which uses boundary elements to discretize the surface of the conductors. BCM combines the weighted least-squares approach for the construction of approximation functions with a boundary integral formulation for the governing equations. A linear base interpolating polynomial that can vary from cloud to cloud is employed. The boundary integrals are computed by using a cell structure and different schemes have been used to evaluate the weakly singular and non-singular integrals. A singular value decomposition (SVD) based acceleration technique is employed to solve the dense linear system of equations arising in BCM. The performance of BCM is compared with BEM for several 3D examples. Copyright © 2004 John Wiley & Sons, Ltd. [source] In-plane vibrations of shear deformable curved beamsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN ENGINEERING, Issue 11 2001Moshe Eisenberger Abstract This paper presents the exact dynamic stiffness matrix for a circular beam with a uniform cross-section. The stiffness matrix is frequency dependent, and the natural frequencies are those that cause the matrix to become singular. Using this matrix the exact natural frequencies of circular beams with various boundary conditions are calculated and compared with available results in the literature. Copyright © 2001 John Wiley & Sons, Ltd. [source] Linearized and non-linear acoustic/viscous splitting techniques for low Mach number flowsINTERNATIONAL JOURNAL FOR NUMERICAL METHODS IN FLUIDS, Issue 10 2003Mohammad Farshchi Abstract Computation of the acoustic disturbances generated by unsteady low-speed flow fields including vortices and shear layers is considered. The equations governing the generation and propagation of acoustic fluctuations are derived from a two-step acoustic/viscous splitting technique. An optimized high order dispersion,relation,preserving scheme is used for the solution of the acoustic field. The acoustic field generated by a corotating vortex pair is obtained using the above technique. The computed sound field is compared with the existing analytic solution. Results are in good agreement with the analytic solution except near the centre of the vortices where the acoustic pressure becomes singular. The governing equations for acoustic fluctuations are then linearized and solved for the same model problem. The difference between non-linear and linearized solutions falls below the numerical error of the simulation. However, a considerable saving in CPU time usage is achieved in solving the linearized equations. The results indicate that the linearized acoustic/viscous splitting technique for the simulation of acoustic fluctuations generation and propagation by low Mach number flow fields seems to be very promising for three-dimensional problems involving complex geometries. Copyright © 2003 John Wiley & Sons, Ltd. [source] Urban Capitalisms: European Models in CompetitionINTERNATIONAL JOURNAL OF URBAN AND REGIONAL RESEARCH, Issue 2 2005DOMINIQUE LORRAIN This article takes as its starting point a central issue for the urban social sciences: comparison. Local government is a theme where much is singular, contingent and idiosyncratic, and international comparison reinforces this tendency towards diversity. Therefore, the capacity to generalize becomes a real issue. The central argument of this article is that, beyond any first-level complexity, the organization of the urban services sector in European countries basically follows three major ,models'. These simplified forms represent ways of combining public policy principles with a market economy. As such, they may be read as specific versions of urban capitalism. All three ,models' are European in origin, and nowadays find themselves in competition. In order to establish the features of these models , simplified forms of more complex phenomena , it is necessary to introduce a historical reading of overall choices of institutional and policy architecture. It is necessary to trace the importance of firms and to study the momentum of crisis and tension, as these give an internal view of phenomena that are generally regarded as natural. Ce texte part d'un problème central pour les sciences sociales urbaines, celui de la comparaison. L'objet urbain pousse à la singularité; les comparaisons internationales renforcent cette tendance; se pose donc un vrai problème de généralisation. La thèse soutenue est qu'au-delà de toute complexité de premier rang, constatée dans l'organisation de chaque service urbain dans les pays européens, ceux-ci au fond ressortent de trois grands modèles. Ces formes simplifiées, ou modèles, représentent autant de manières de combiner des principes d'action publique à une économie de marché; on peut les lire comme autant de versions du capitalisme urbain. En étant tous les trois représentés en Europe ces ,modèles' se trouvent aujourd'hui en compétition. Pour parvenir à dégager ces propriétés modéliques, formes simplifiées de phénomènes plus complexes, il convient d'introduire une lecture historique des grands choix en matières d'architectures institutionnelles et politiques. Il faut accorder de l'importance aux firmes et suivre les moments de mise en tension; ils permettent de saisir ce qui semble naturel dans le fonctionnement ordinaire. [source] Reliable computing in estimation of variance componentsJOURNAL OF ANIMAL BREEDING AND GENETICS, Issue 6 2008I. Misztal Summary The purpose of this study is to present guidelines in selection of statistical and computing algorithms for variance components estimation when computing involves software packages. For this purpose two major methods are to be considered: residual maximal likelihood (REML) and Bayesian via Gibbs sampling. Expectation-Maximization (EM) REML is regarded as a very stable algorithm that is able to converge when covariance matrices are close to singular, however it is slow. However, convergence problems can occur with random regression models, especially if the starting values are much lower than those at convergence. Average Information (AI) REML is much faster for common problems but it relies on heuristics for convergence, and it may be very slow or even diverge for complex models. REML algorithms for general models become unstable with larger number of traits. REML by canonical transformation is stable in such cases but can support only a limited class of models. In general, REML algorithms are difficult to program. Bayesian methods via Gibbs sampling are much easier to program than REML, especially for complex models, and they can support much larger datasets; however, the termination criterion can be hard to determine, and the quality of estimates depends on a number of details. Computing speed varies with computing optimizations, with which some large data sets and complex models can be supported in a reasonable time; however, optimizations increase complexity of programming and restrict the types of models applicable. Several examples from past research are discussed to illustrate the fact that different problems required different methods. [source] Deferring to resources: collaborations around traditional vs computer-based notesJOURNAL OF COMPUTER ASSISTED LEARNING, Issue 1 2002C. Crook Abstract Undergraduate students were observed engaged in a species of collaboration rarely studied and yet which is grounded in an authentic form of normal study practice: namely, revising a course in preparation for an exam. Pairs of undergraduates were convened for recorded sessions in which they did this around either their own personal lecture notes or around a set of notes authored by the lecturer and made available as web-readable computer documents. Although the goals, motives and orientations of these pairings were similar, the nature of the collaborative resource effected the character and rhythm of the joint conversation. The computer-based documents led to less on-task collaborative talk. Moreover, these documents sustained conversation that was more fragmented around successive short topics. Observations are made regarding how certain discursive openings are more readily afforded when revision talk is mediated by a less singular, authorised, and directive form of document. [source] Pose Optimization of Serial Manipulators Using Knowledge of Their Velocity-Degenerate (Singular) ConfigurationsJOURNAL OF FIELD ROBOTICS (FORMERLY JOURNAL OF ROBOTIC SYSTEMS), Issue 5 2003Scott B. Nokleby This work investigates the exploitation of velocity-degenerate configurations to optimize the pose of either nonredundant or redundant serial manipulators to sustain desired wrenches. An algorithm is developed that determines a desirable start point for the optimization of a serial manipulator's pose. The start-point algorithm (SPA) uses analytical expressions of the velocity-degenerate (singular) configurations of a serial manipulator to determine a pose that would be best suitable to sustain a desired wrench. Results for an example redundant serial manipulator are presented. The example results show that by using the SPA with the optimization routine, the resulting poses obtained require less effort from the actuators when compared to the poses obtained without using the SPA. It is shown that when no constraint is imposed on the position of the end-effector, the SPA excels at providing a better solution with less iterations than running the optimization without the SPA. © 2003 Wiley Periodicals, Inc. [source] Metaphor and the Dynamics of Knowledge in Organization Theory: A Case Study of the Organizational Identity Metaphor*JOURNAL OF MANAGEMENT STUDIES, Issue 4 2006Joep P. Cornelissen abstract Despite the increased salience of metaphor in organization theory, there is still very little conceptual machinery for capturing and explaining how metaphor creates and/or reorders knowledge within organization theory. Moreover, prior work on metaphor has insufficiently accounted for the context of interpreting a metaphor. Many metaphors in organization theory, including the ,organizational identity' metaphor, have often been treated in singular and monolithic terms; seen to offer a similar or largely synonymous interpretation to theorists and researchers working along the entire spectrum of disciplines (e.g. organizational behaviour, organizational psychology) in organization theory. We argue in this paper that contextual variation however exists in the interpretation of metaphors in organization theory. This argument is developed by proposing and elaborating on a so-called image-schematic model of metaphor, which suggests that the image-schemata (abstract imaginative structures) that are triggered by the metaphorical comparison of concepts may vary among individuals. Accordingly, once different schemata are triggered the completion and interpretation of a metaphor may equally vary among different individuals or, indeed, research communities. These points associated with the image-schematic model of metaphor are illustrated with a case study of the ,organizational identity' metaphor. The case study shows that this particular metaphor has spiralled out into different research communities and has been comprehended in very different ways as different communities work from very different conceptions, or image-schemata, of ,organization' and ,identity', and use different theoretical frameworks and constructs as a result. The implications of the image-schematic view of metaphor for knowledge development and theoretical progress in organization theory are discussed. [source] Safety of, and biological and functional response to, a novel metallic implant for the management of focal full-thickness cartilage defects: Preliminary assessment in an animal model out to 1 yearJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 5 2006Carl A. Kirker-Head Abstract Focal full-thickness cartilage lesions of the human medial femoral condyle (MFC) can cause pain and functional impairment. Affected middle-aged patients respond unpredictably to existing treatments and knee arthroplasty may be required, prompting risk of revision. This study assesses the safety of, and biological and functional response to, a metallic resurfacing implant which may delay or obviate the need for traditional arthroplasty. The anatomic contour of the surgically exposed MFC of six adult goats was digitally mapped and an 11 mm diameter full-thickness osteochondral defect was created. An anchor-based Co,Cr resurfacing implant, matching the mapped articular contour, was implanted. Each goat's contralateral unoperated femorotibial joint was used as a control. Postoperative outcome was assessed by lameness examination, radiography, arthroscopy, synoviocentesis, necropsy, and histology up to 26 (n,=,3) or 52 (n,=,3) weeks. By postoperative week (POW) 4, goats demonstrated normal range of motion, no joint effusion, and only mild lameness in the operated limb. By POW 26 the animals were sound with only occasional very mild lameness. Arthroscopy at POW 14 revealed moderate synovial inflammation and a chondral membrane extending centrally across the implant surface. Radiographs at POWs 14 to 52 implied implant stability in the operated joints, as well as subchondral bone remodeling and mild exostosis formation in the operated and contralateral unoperated joints of some goats. By POW 26, histology revealed new trabecular bone abutting the implant. At POWs 26 and 52 MFC cartilage was metachromatic and intact in the operated and unoperated femorotibial joints. Proximal tibiae of some operated and unoperated limbs demonstrated limited subchondral bone remodeling and foci of articular cartilage fibrillation and thinning. The chondral membrane crossing the prosthesis possessed a metachromatic matrix containing singular and clustered chondrocytes. Our data imply the safety, biocompatibility, and functionality of the implant. Focal articular damage was documented in the operated joints at POWs 26 and 52, but lesions were much reduced over those previously reported in untreated defects. Expanded animal or preclinical human studies are justified. © 2006 Orthopaedic Research Society. Published by Wiley Periodicals, Inc. J Orthop Res [source] Spinal degenerative disk disease (DDD) in female macaque monkeys: epidemiology and comparison with womenJOURNAL OF ORTHOPAEDIC RESEARCH, Issue 3 2002Patricia Ann Kramer Spinal degenerative disk disease (DDD) in a radiographic, cross-sectional sample of 192 female macaque monkeys, approximately 5,30 years old, is described. The presence and extent of disk space narrowing (DSN) and anterior osteophytosis were assessed with reference to age, average lifetime body mass, and distribution within the thoracolumbar spine. Age was a strong correlate of disk narrowing and osteophytosis, with early signs appearing at equivalent ages in both species and increasing in prevalence thereafter. Macaques showed a far greater prevalence of DDD, especially in the oldest age group, than has been reported in the human data. Body mass was associated with disk narrowing in the macaque, but not with osteophytosis. The two species differed little in the pattern of distribution of DDD along the spine. Our results suggest that bipedality is not the singular, or even the most important, biomechanical factor in the development of human DDD. Rather, others shared postural regimes, e.g., sitting, may be responsible for the onset and progression of DDD in both species. The macaque model could substantially add to the under-standing and, potentially, treatment of this oftentimes debilitating condition. © 2002 Orthopaedic Research Society. Published by Elsevier Science Ltd. All rights reserved. [source] Current usage of the epicene pronoun in written EnglishJOURNAL OF SOCIOLINGUISTICS, Issue 3 2002Maciej Baranowski This paper deals with current epicenepronominal usage in written English. The first part focuses on the prescription of the so,called generic he and includes a short review of research into epicene pronominal usage in the last three decades. The results of previous research serve as a background to the present study, which, based on two corpora of written English, aims at elucidating singular epicene pronominal choices in the writing of British and American writers. The study shows that the traditional form he is no longer predominant, while singular they is the pronoun most likely to be used. He or she is shown to be used rather rarely. It is argued that the choice of singular epicene pronoun is considerably influenced by the semanto,syntactic type of the antecedent and by the social roles stereotypically associated with the referent. Also, differences between British and American writers are discussed. It is shown that American writers are more conservative in their choice of singular epicene pronoun and an explanation of the difference is suggested. [source] Effect of Magnesium Oxide Addition on Surface Roughening of Alumina Grains in Anorthite LiquidJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 4 2003Mi Jin Kim Alumina sintered with 5 wt% anorthite at 1620°C for 48 h has grains with flat boundaries and a size distribution representing abnormal grain growth. TEM observations of the grain triple junctions show flat grain surfaces, some of which are the (0001), ([Onemacr]012), and (1[Onemacr]01) planes. HRTEM observations confirm these surfaces to be atomically flat and hence singular. When sintered further after embedding in MgO powder, the {0001} and { 01[Onemacr]2} planes remain flat, but curved surface segments also appear. These curved surface segments are confirmed to be atomically rough by HRTEM. They are connected to the flat segments with discontinuously changing slopes. Thus, when MgO is added, the singular and rough surface phases coexist. [source] Abnormal Grain Growth in Alumina with Anorthite Liquid and the Effect of MgO AdditionJOURNAL OF THE AMERICAN CERAMIC SOCIETY, Issue 6 2002Chan Woo Park Abnormal grain growth (AGG) in alumina with anorthite liquid has been observed with varying anorthite and MgO contents, at 1620°C. When only anorthite is added to form a liquid matrix, the grain,liquid interfaces have either flat or hill-and-valley shapes indicating atomically flat (singular) structures. The large grains grow at accelerated rates to produce AGG structures with large grains elongated along their basal planes. This is consistent with the slow growth at low driving forces and accelerated growth above a critical driving force predicted by the two-dimensional nucleation theory of surface steps. With increasing temperature, the AGG rate increases. The number density of the abnormally large grains increases with increasing anorthite content. The addition of MgO causes some grain,liquid interfaces to become curved and hence atomically rough. The grains also become nearly equiaxed. With increasing MgO content the number density of the abnormally large grains increases until the grain growth resembles normal growth. This result is qualitatively consistent with the decreasing surface step free energy associated with partial interface roughening transition. [source] Nonlinear functionals of the periodogramJOURNAL OF TIME SERIES ANALYSIS, Issue 5 2002GILLES FAY A central limit theorem is stated for a wide class of triangular arrays of nonlinear functionals of the periodogram of a stationary linear sequence. Those functionals may be singular and not-bounded. The proof of this result is based on Bartlett decomposition and an existing counterpart result for the periodogram of an independent and identically distributed sequence, here taken to be the driving noise. The main contribution of this paper is to prove the asymptotic negligibility of the remainder term from Bartlett decomposition, feasible under short dependence assumption. As it is highlighted by applications (to estimation of nonlinear functionals of the spectral density, robust spectral estimation, local polynomial approximation and log-periodogram regression), this extends may results until then tied to Gaussian assumption. [source] The Languages of SiberiaLINGUISTICS & LANGUAGE COMPASS (ELECTRONIC), Issue 1 2009Edward J. Vajda Although Russian today is the dominant language in virtually every corner of North Asia, Siberia and the Northern Pacific Rim of Asia remain home to over three dozen mutually unintelligible indigenous language varieties. Except for Tuvan, Buryat, and Yakut, most are rapidly losing ground to Russian if not already critically endangered. Several more have already become extinct in the four centuries since the area's incorporation into the Russian state. From an ethnographic perspective, Siberian languages merit attention for their interplay of pastoral and hunter,gatherer influences and also for the fact that Siberia represents the staging ground for prehistoric migrations into the Americas. North Asia contains several autochthonous microfamilies and isolates not found outside this region , the so-called ,Paleo-Asiatic' (or ,Paleosiberian') languages Ket, Yukaghir, Nivkh, and the Chukotko-Kamchatkan microfamily, which includes Chukchi, Koryak, and Itelmen. Ainu, formerly spoken on Sakhalin and the Kuriles as well as in Hokkaido, and the three varieties of Eskimoan spoken in historic times on the Russian side of Bering Strait, likewise belong to the earlier, non-food producing layers of ethnolinguistic diversity in North Asia. All of these languages, aside from Eskimoan, are entirely autochthonous to the northern half of Asia. Siberian languages spoken by pastoral groups, on the other hand, belong to families represented more prominently elsewhere. Families, such as Uralic, Turkic, Mongolic, and especially Tungusic (the northern branch of the Tungus-Manchu family), became dominant in Siberia long before the coming of the Russians. As an extension of pastoral Inner Eurasia, Siberia displays many traits characteristic of a linguistic area: suffixal agglutination, widespread dependent marking typology, a fairly elaborate system of spatial case markers, and the use of case suffixes or postpositions to signal syntactic subordination. There are also notable idiosyncratic features, particularly among the so-called Paleo-Siberian languages. These include the areally atypical feature of possessive prefixes and verb-internal subject/object prefixes in Ket, the unique verb-internal focus markers of Yukaghir, the extensive numeral allomorphs that serve as nominal classifiers in Nivkh, and the reduplicative stem augmentation used by Chukchi nouns to express the absolutive singular (in contrast to plurals and oblique case forms, where the stem is simple). While North Asia has long been the preserve of linguists writing in Russian or German (including many Finns and Hungarians), since the collapse of the Soviet Union the number of English-language treatments of Siberian languages is increasing. [source] Constant-sign solutions for singular systems of Fredholm integral equationsMATHEMATICAL METHODS IN THE APPLIED SCIENCES, Issue 15 2010Ravi P. Agarwal Abstract We consider the system of Fredholm integral equations where T>0 is fixed and the nonlinearities Hi(t, u1, u2, ,, un) can be singular at t=0 and uj=0 where j,{1, 2, ,, n}. Criteria are offered for the existence of constant-sign solutions, i.e. ,iui(t),0 for t,[0, 1] and 1,i,n, where ,i,{1,,1} is fixed. We also include an example to illustrate the usefulness of the results obtained. Copyright © 2010 John Wiley & Sons, Ltd. [source] | |||||||||||||||||||||||||||||||