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General Structure (general + structure)
Selected AbstractsThe structure of Estonian personal values: a lexical approachEUROPEAN JOURNAL OF PERSONALITY, Issue 3 2002Toivo Aavik The main purpose of this paper is to investigate the variety of value describing words and interrelation of value categories in the Estonian language. To accomplish this aim, a psycholexical approach was adopted, during which a set of 560 value-related words was selected from the Estonian Orthological Dictionary and the results were compared with the Schwartz Values Survey (SVS). When principal-component analysis was applied on the self-ratings of a reduced list of 78 value-related words, six factors emerged and were labelled as benevolence, self-enhancement, broadmindedness, hedonism, conservatism, and self-realization. However, all these themes are interrelated and load on a singular secondary dimension. The constructs measured by SVS and the value categories in Estonian were only partially interchangeable; moderate correlations imply an imperfect correspondence: each theme was related to many categories on the other questionnaire. However, a significant general structure refers to the same two-dimensional level of higher-order values described by Schwartz in 1992. Copyright © 2002 John Wiley & Sons, Ltd. [source] PERSPECTIVE: MODELS OF SPECIATION: WHAT HAVE WE LEARNED IN 40 YEARS?EVOLUTION, Issue 10 2003Sergey Gavrilets Abstract Theoretical studies of speciation have been dominated by numerical simulations aiming to demonstrate that speciation in a certain scenario may occur. What is needed now is a shift in focus to identifying more general rules and patterns in the dynamics of speciation. The crucial step in achieving this goal is the development of simple and general dynamical models that can be studied not only numerically but analytically as well. I review some of the existing analytical results on speciation. I first show why the classical theories of speciation by peak shifts across adaptive valleys driven by random genetic drift run into trouble (and into what kind of trouble). Then I describe the Bateson-Dobzhansky-Muller (BDM) model of speciation that does not require overcoming selection. I describe exactly how the probability of speciation, the average waiting time to speciation, and the average duration of speciation depend on the mutation and migration rates, population size, and selection for local adaptation. The BDM model postulates a rather specific genetic architecture of reproductive isolation. I then show exactly why the genetic architecture required by the BDM model should be common in general. Next I consider the multilocus generalizations of the BDM model again concentrating on the qualitative characteristics of speciation such as the average waiting time to speciation and the average duration of speciation. Finally, I consider two models of sympatric speciation in which the conditions for sympatric speciation were found analytically. A number of important conclusions have emerged from analytical studies. Unless the population size is small and the adaptive valley is shallow, the waiting time to a stochastic transition between the adaptive peaks is extremely long. However, if transition does happen, it is very quick. Speciation can occur by mutation and random drift alone with no contribution from selection as different populations accumulate incompatible genes. The importance of mutations and drift in speciation is augmented by the general structure of adaptive landscapes. Speciation can be understood as the divergence along nearly neutral networks and holey adaptive landscapes (driven by mutation, drift, and selection for adaptation to a local biotic and/or abiotic environment) accompanied by the accumulation of reproductive isolation as a by-product. The waiting time to speciation driven by mutation and drift is typically very long. Selection for local adaptation (either acting directly on the loci underlying reproductive isolation via their pleiotropic effects or acting indirectly via establishing a genetic barrier to gene flow) can significantly decrease the waiting time to speciation. In the parapatric case the average actual duration of speciation is much shorter than the average waiting time to speciation. Speciation is expected to be triggered by changes in the environment. Once genetic changes underlying speciation start, they go to completion very rapidly. Sympatric speciation is possible if disruptive selection and/or assortativeness in mating are strong enough. Sympatric speciation is promoted if costs of being choosy are small (or absent) and if linkage between the loci experiencing disruptive selection and those controlling assortative mating is strong. [source] Gauged supergravities in various spacetime dimensions,FORTSCHRITTE DER PHYSIK/PROGRESS OF PHYSICS, Issue 8 2007M. Weidner Abstract In this review article we study the gaugings of extended supergravity theories in various space-time dimensions. These theories describe the low-energy limit of non-trivial string compactifications. For each theory under consideration we review all possible gaugings that are compatible with supersymmetry. They are parameterized by the so-called embedding tensor which is a group theoretical object that has to satisfy certain representation constraints. This embedding tensor determines all couplings in the gauged theory that are necessary to preserve gauge invariance and supersymmetry. The concept of the embedding tensor and the general structure of the gauged supergravities are explained in detail. The methods are then applied to the half-maximal (N = 4) supergravities in d = 4 and d = 5 and to the maximal supergravities in d = 2 and d = 7. Examples of particular gaugings are given. Whenever possible, the higher-dimensional origin of these theories is identified and it is shown how the compactification parameters like fluxes and torsion are contained in the embedding tensor. [source] Near-surface models in Saudi ArabiaGEOPHYSICAL PROSPECTING, Issue 6 2007Ralph Bridle ABSTRACT A single-layer model of the near surface throughout the Kingdom of Saudi Arabia is available. While this simple model suffices for most areas and large subsurface structures, it fails in situations where the surface topography is complex, the base of weathering is below the datum, or where the time structural closure is less than the uncertainty in the static correction. In such cases, multiple-layered models that incorporate velocities derived from analysis of first arrivals picked from seismic shot records have proved to be successful in defining the lateral heterogeneity of the near surface. The additional velocity information obtained from this first-arrival analysis (direct as well as refracted arrivals) vastly improves the velocity,depth model of the near surface, regardless of the topography. Static corrections computed from these detailed near-surface velocity models have significantly enhanced subsurface image focusing, thereby reducing the uncertainty in the closure of target structures. Other non-seismic methods have been used either to confirm qualitatively or to enhance the layer models previously mentioned. Gravity data may be particularly useful in sandy areas to confirm general structure, while geostatistical modelling of vibrator base-plate attributes has yielded information that enhances the velocity field. In the global context, exploration targets of the oil and gas industry are seeking smaller and lower relief-time structures. Thus, near-surface models will need to enhance and integrate these methods, particularly in areas where the assumption of flat-lying near-surface layers cannot be met. [source] A constitutive model for the dynamic and high-pressure behaviour of a propellant-like material: Part I: Experimental background and general structure of the modelINTERNATIONAL JOURNAL FOR NUMERICAL AND ANALYTICAL METHODS IN GEOMECHANICS, Issue 6 2001Hervé Trumel Abstract This paper is the first part of a work that aims at developing a mechanical model for the behaviour of propellant-like materials under high confining pressure and strain rate. The behaviour of a typical material is investigated experimentally. Several microstructural deformation processes are identified and correlated with loading conditions. The resulting behaviour is complex, non-linear, and characterized by multiple couplings. The general structure of a relevant model is sought using a thermodynamic framework. A viscoelastic-viscoplastic-compaction model structure is derived under suitable simplifying assumptions, in the framework of finite, though moderate, strains. Model development, identification and numerical applications are given in the companion paper. Copyright © 2001 John Wiley & Sons, Ltd. [source] INTEGRATED MODELING FOR WATERSHED MANAGEMENT: MULTIPLE OBJECTIVES AND SPATIAL EFFECTS,JOURNAL OF THE AMERICAN WATER RESOURCES ASSOCIATION, Issue 2 2002Stephen C. Newbold ABSTRACT: This paper presents an optimization framework for prioritizing sites for wetlands restoration on a watershed or landscape scale. The framework is designed for analyzing the potential environmental impacts of alternative management strategies while accounting for economic constraints, thereby aiding decision makers in explicitly considering multiple management objectives. The modeling strategy consists of two phases. First, relationships between the configuration of land use types in a watershed and valued ecosystem services are specified mathematically. Second, those functions are incorporated into a spatial optimization model that allows comparisons of the expected environmental impacts and economic costs of management strategies that change the configuration of land use in the watershed. By way of a stylized example, this paper develops the general structure of the framework, presents simulation results based on two production functions for ecosystem services, and discusses the potential utility of the methodology for watershed management. [source] Nonsteroidal aromatase inhibitors: Recent advancesMEDICINAL RESEARCH REVIEWS, Issue 3 2002Maurizio Recanatini Abstract Aromatase is the cytochrome P450 enzyme responsible for the last step of estrogen biosynthesis, and aromatase inhibitors constitute an important class of drugs in clinical use for the treatment of breast cancer. Nonsteroidal aromatase inhibitors (NSAIs) are competitive inhibitors of aromatase, which bind to the enzyme active site by coordinating the iron atom present in the heme group of the P450 protein. Presently, third generation NSAIs are in use, and research efforts are being carried out both to identify new molecules of therapeutic interest and to clarify the mechanism of action. In this article, we present a survey of the compounds that have been recently reported as NSAIs, to provide a broad view on the general structure,activity relationships of the class. Moreover, starting from the current knowledge of the mechanistic aspects of aromatase action and from recent theoretical work on the molecular modeling of both enzyme and inhibitors, we try to indicate a way to integrate these different studies in view of a more general understanding of the aromeatase-inhibitor system. Finally, some aspects regarding the possible future development of the field are considered briefly. © 2002 Wiley Periodicals, Inc. Med Res Rev, 22, No. 3, 282,304, 2002; Published online in wiley InterScience (www.interscience.wiley.com). DOI 10.1002/med.10010 [source] Dance events as a caregiver intervention for persons with dementiaNURSING INQUIRY, Issue 3 2000Liisa Palo-Bengtsson Dance events as a caregiver intervention for persons with dementia The aim of the study was to illuminate the phenomenon of dance events as a caregiver intervention for persons with dementia in one nursing home as described by the caregivers. Seven caregivers were interviewed. The interviews were unstructured and conducted while the caregivers were watching a video of dance events arranged in the nursing home. The analysis was carried out using the phenomenological method developed by Giorgi. The results are presented in five consistent themes: (1) prerequisites for dance events; (2) creating and preparing different kinds of activities related to the dance events; (3) emotional arousal; (4) caregivers' situational understanding; and (5) dance events and contextual consequences and synthesis into a general structure. The meaning of the dance events as a caregiver intervention was founded not only on the dancing itself but also encompassed the ontological state of ,being together'. [source] On the sensitivity of the restricted least squares estimators to covariance misspecificationTHE ECONOMETRICS JOURNAL, Issue 3 2007Alan T.K. Wan Summary, Traditional econometrics has long stressed the serious consequences of non-spherical disturbances for the estimation and testing procedures under the spherical disturbance setting, that is, the procedures become invalid and can give rise to misleading results. In practice, it is not unusual, however, to find that the parameter estimates do not change much after fitting the more general structure. This suggests that the usual procedures may well be robust to covariance misspecification. Banerjee and Magnus (1999) proposed sensitivity statistics to decide if the Ordinary Least Squares estimators of the coefficients and the disturbance variance are sensitive to deviations from the spherical error assumption. This paper extends their work by investigating the sensitivity of the restricted least squares estimator to covariance misspecification where the restrictions may or may not be correct. Large sample results giving analytical evidence to some of the numerical findings reported in Banerjee and Magnus (1999) are also obtained. [source] KIERKEGAARD ON TAKING AN OUTING TO DEER PARKTHE HEYTHROP JOURNAL, Issue 3 2007T. F. MORRIS I offer an exegesis of a few pages of the Concluding Unscientific Postscript and explain how going to Deer Park religiously fits into the general structure of Kierkegaard's thought. Because desiring God requires passion, and passion requires energy, there is a limit to how long any individual person can maintain a continuous desire for God. Kierkegaard discusses how a person who is at that limit can maintain a less intense love of God as he allows himself to desire temporal things. [source] Core Curricular Elements for Fellowship Training in International Emergency MedicineACADEMIC EMERGENCY MEDICINE, Issue 7 2010Jamil Bayram MD ACADEMIC EMERGENCY MEDICINE 2010; 17:748,757 © 2010 by the Society for Academic Emergency Medicine Abstract Objectives:, The objective was to describe the common educational goals, curricular elements, and methods of evaluation used in international emergency medicine (IEM) fellowship training programs currently. IEM fellowship programs have been developed to provide formal training for emergency physicians (EPs) interested in pursuing careers in IEM. Those fellowships are variable in scope, objectives, and duration. Previously published articles have suggested a general curriculum structure for IEM fellowships. Methods:, A search of MEDLINE, EMBASE, and CINAHL databases from 1950 to June 2008 was performed, combining the terms international, emergency medicine, and fellowship. Online curricula and descriptive materials from IEM fellowships listed by the Society for Academic Emergency Medicine (SAEM) were reviewed. Knowledge and skill areas common to multiple programs were organized in discrete categories. IEM fellowship directors were contacted for input and feedback. Results:, Eight articles on IEM fellowships were identified. Two articles described a general structure for fellowship curriculum. Sixteen of 20 IEM fellowship programs had descriptive materials posted online. These information sources, plus input from seven fellowship program directors, yielded the following seven discrete knowledge and skill areas: 1) emergency medicine systems development, 2) humanitarian relief, 3) disaster management, 4) public health, 5) travel and field medicine, 6) program administration, and 7) academic skills. Conclusions:, While IEM fellowships vary with regard to objectives and structure, this article presents an overview of the current focus of IEM fellowship training curricula that could serve as a resource for IEM curriculum development at individual institutions. [source] A generalized mathematical model for non-catalytic gas-solid reactionsCHINESE JOURNAL OF CHEMISTRY, Issue 4 2000Yan Zi-Feng Abstract Based on a general classification and characteristic comparison of the existing models, a new model for non-catalytic gas-solid reactions is proposed and a general formulation for the model in terms of the solid conversion, X, is presented in mis paper. The model, referred to the generalized model, is demonstrated to be applicable to any solid reactant of general structure ranging from highly porous to nonporous materials. It is shown that the generalized model incorporates the grain and pore structure for a solid pellet and can be reduced to the grain and random pore models as extreme cases. [source] On Hamiltonian perturbations of hyperbolic systems of conservation laws I: Quasi-Triviality of bi-Hamiltonian perturbationsCOMMUNICATIONS ON PURE & APPLIED MATHEMATICS, Issue 4 2006Boris Dubrovin We study the general structure of formal perturbative solutions to the Hamiltonian perturbations of spatially one-dimensional systems of hyperbolic PDEs vt + [,(v)]x = 0. Under certain genericity assumptions it is proved that any bi-Hamiltonian perturbation can be eliminated in all orders of the perturbative expansion by a change of coordinates on the infinite jet space depending rationally on the derivatives. The main tool is in constructing the so-called quasi-Miura transformation of jet coordinates, eliminating an arbitrary deformation of a semisimple bi-Hamiltonian structure of hydrodynamic type (the quasi-triviality theorem). We also describe, following [35], the invariants of such bi-Hamiltonian structures with respect to the group of Miura-type transformations depending polynomially on the derivatives. © 2005 Wiley Periodicals, Inc. [source] Design of multiple tuned mass dampers by using a numerical optimizerEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 2 2005Nam Hoang Abstract A new method to design multiple tuned mass dampers (multiple TMDs) for minimizing excessive vibration of structures has been developed using a numerical optimizer. It is a very powerful method by which a large number of design variables can be effectively handled without imposing any restriction before the analysis. Its framework is highly flexible and can be easily extended to general structures with different combinations of loading conditions and target controlled quantities. The method has been used to design multiple TMDs for SDOF structures subjected to wide-band excitation. Some novel results have been obtained. To reduce displacement response of the structure, the optimally designed multiple TMDs have distributed natural frequencies and distinct damping ratios at low damping level. The obtained optimal configuration of TMDs was different from the earlier analytical solutions and was proved to be the most effective. A robustness design of multiple TMDs has also been presented. Robustness is defined as the ability of TMDs to function properly despite the presence of uncertainties in the parameters of the system. Numerical examples of minimizing acceleration structural response have been given where the system parameters are uncertain and are modeled as independent normal variates. It was found that, in case of uncertainties in the structural properties, increasing the TMD damping ratios along with expanding the TMD frequency range make the system more robust. Meanwhile, if TMD parameters themselves are uncertain, it is necessary to design TMDs for higher damping ratios and a narrower frequency range. Copyright © 2004 John Wiley & Sons, Ltd. [source] Isolation and X-Ray Structures of Reactive Intermediates of Organocatalysis with Diphenylprolinol Ethers and with ImidazolidinonesHELVETICA CHIMICA ACTA, Issue 11 20085-Repulsion, A Survey, Comparison with Computed Structures, the Geminal-Diaryl Effect at Work, with 1-Acyl-imidazolidinones: The Abstract Reaction of 2-phenylacetaldehyde with the Me3Si ether of diphenyl-prolinol, with removal of H2O, gives a crystalline enamine (1). The HBF4 salts of the MePh2Si ether of diphenyl-prolinol and of 2-(tert -butyl)-3-methyl- and 5-benzyl-2,2,3-trimethyl-1,3-imidazolidin-4-one react with cinnamaldehyde to give crystalline iminium salts 2, 3, and 4. Single crystals of the enamine and of two iminium salts, 2 and 3, were subjected to X-ray structure analysis (Figs.,1, 2, and 6), and a 2D-NMR spectrum of the third iminium salt was recorded (Fig.,7). The crystal and NMR structures confirm the commonly accepted, general structures of the two types of reactive intermediates in organocatalysis with the five-membered heterocycles, i.e., D, E (Scheme,2). Fine details of the crystal structures are discussed in view of the observed stereoselectivities of the corresponding reactions with electrophiles and nucleophiles. The structures 1 and 2 are compared with those of other diphenyl-prolinol derivatives (from the Cambridge File CSD; Table,1) and discussed in connection with other reagents and ligands, containing geminal diaryl groups and being used in enantioselective synthesis (Fig.,4). The iminium ions 3 and 4 are compared with N -acylated imidazolidinones F and G (Figs.,9, 12, and 13, and Table,3), and common structural aspects such as minimalization of 1,5-repulsion (the ,A1,3 -effect'), are discussed. The crystal structures of the simple diphenyl-prolinol,HBF4 salt (Fig.,3) and of Boc- and benzoyl-(tert -butyl)methyl-imidazolidinone (Boc-BMI and Bz-BMI, resp.; Figs.,10 and 11) are also reported. Finally, the crystal structures are compared with previously published theoretical structures, which were obtained from high-level-of-theory DFT calculations (Figs.,5 and 8, and Table,2). Delicate details including pyramidalization of trigonal N-atoms, distortions around iminium CN bonds, shielding of diastereotopic faces, and the , -interaction between a benzene ring and a Me group match so well with, and were actually predicting the experimental results that the question may seem appropriate, whether one will soon start considering to carry out such calculations before going to the laboratory for experimental optimizations. [source] | ||||||||||||||||