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General Theory (general + theory)
Selected AbstractsCritiquing the General Theory of Crime's Empirical Evidence: Does the Evidence Support the Theory?JOURNAL OF FAMILY THEORY & REVIEW, Issue 3 2009Jennifer M. Crosswhite Gottfredson and Hirschi's general theory of crime proposes that low self-control leads to engagement in deviant behaviors, parents must properly socialize self-control in their children, and self-control fully mediates the parenting-deviance association. A critical analysis of the empirical evidence generated suggests a number of unresolved issues regarding the theory that remain to be investigated. Some of the specific issues addressed include determining which aspects of parenting influence the etiology of self-control and to what extent self-control mediates the parenting-deviance association. [source] Producing Parsons' reputation: Early critiques of Talcott Parsons' social theory and the making of a caricatureJOURNAL OF THE HISTORY OF THE BEHAVIORAL SCIENCES, Issue 2 2010B. Robert Owens This article examines the critical responses to Talcott Parsons' first major work, The Structure of Social Action (1937), and his two subsequent books, Toward a General Theory of Action and The Social System (both 1951). Because Parsons' work was the subject of such virulent debate, we cannot fully understand Parsons' impact on the discipline of sociology without understanding the source and nature of those early criticisms. I trace the responses to Parsons, first through book reviews and private letters and then in the more substantial statements of C. Wright Mills, George Homans, and Alvin Gouldner, from the largely positive but superficial reception of Structure to the polemics that followed Parsons' 1951 works. In the late 1930s and 1940s, Parsons' reputation grew steadily but there remained no careful reception of Structure, fostering resentment toward Parsons in some quarters while precluding a sophisticated understanding of his work. After 1951, a few critics capitalized on that tension, writing sweeping rejections of Parsons' work that spoke to a much broader audience of sociologists. That dynamic, coupled with Parsons' own indifference toward his harshest critics, produced a situation in which many sociologists simply chose not to read Parsons in the 1950s and 1960s, reinforcing a caricature and distorting perceptions of Parsons' place in mid-twentieth-century American sociology. © 2010 Wiley Periodicals, Inc. [source] Über die Schlusspassage der General Theory, Gedanken zum Einfluss Ökonomischer Theorien auf die PolitikPERSPEKTIVEN DER WIRTSCHAFTSPOLITIK, Issue 1 2000C. Christian Von Weizsäcker First page of article [source] Front and Back Covers, Volume 25, Number 5.ANTHROPOLOGY TODAY, Issue 5 2009October 200 Front and back cover caption, volume 25 issue 5 FIELDWORK AND TECHNOLOGY The images on the front and back covers illustrate two of several reflections in this issue on the impacts of technology on the world studied by anthropologists. On the front cover, an internet cafe is one of the first sights to greet visitors to Dhunche, once a ,remote' area in northern Nepal. On the back cover, a youth tries out a telescope during the commemoration of the confirmation of Einstein's General Theory of Relativity at Roça Sundy, Príncipe, where Arthur Eddington observed a total solar eclipse. In his editorial, Bob Simpson remarks on how much the craft of fieldwork has changed as a result of the widespread on-site availability of communications technology, placing even the remotest sites within reach of home or employer. In this post-Malinowskian fieldwork, where the distinction between back here and out there has disappeared, what are the implications of this for our craft and for the quality of our obversations? Gisa Weszkalnys reflects on her fieldwork site of Príncipe as the location of one of the most important events in 20th-century science, the confirmation of Einstein's General Theory of Relativity. She overlays the 2009 commemoration of this event, with international institutions promoting scientific knowledge and tourism, with another, colonial history of Príncipe as the focus of a controversy around the alleged use of slave labour in its cocoa plantations. As Kristín Loftsdóttir argues in her article, science and technology are among a range of markers used to determine who is most in need of international development, thus contributing to what she calls the ,racialization of development'. Akbar Ahmed alerts us to the fear in Washington, DC and Islamabad that the Taliban, who have recently taken over his field site in Swat Province, could potentially destabilize world order by appropriating nuclear technology. There are evidently many ways in which science and technology can and do affect our field sites. One of the greatest challenges for anthropology will be to experiment creatively and innovate with appropriate technologies in partnership. In this way we can generate more egalitarian conversations in an atmosphere of mutual respect, trust and tolerance. Whatever fieldwork becomes, it must be founded on such engagement with the broadest of publics, while making the most of these new technologies. [source] Príncipe eclipsed: Commemorating the confirmation of Einstein's Theory of General RelativityANTHROPOLOGY TODAY, Issue 5 2009Gisa Weszkalnys This article reflects on the West African island of Príncipe as the venue of one of the most significant events in 20th century science, the confirmation of Einstein's General Theory of Relativity during an eclipse expedition led by Arthur Eddington. It takes as its starting point the 2009 commemoration of the event, involving international institutions promoting scientific knowledge and tourism, and overlays this with another, colonial history of Príncipe as the focus of a controversy around the alleged use of slave labour in its early 20th century cocoa plantations. What is the anthropologist's license in problematising the commemoration, and what are the specific ethnographic insights afforded by this unique event? [source] Self-control and Resistance to School,CANADIAN REVIEW OF SOCIOLOGY/REVUE CANADIENNE DE SOCIOLOGIE, Issue 4 2000M. Reza Nakhaie Dans cet article, on examine la relation entre l'autocontrôle, le contrôle social et la résistance au système scolaire. Les données d'étude sont tirées d'un sondage réalisé auprès d'étudiants des premier et deuxième cycles du secondaire en Alberta. Les résultats de ce sondage penchent fortement en faveur de la General Theory of Crime (Gottfredson et Hirschi, 1990), selon laquelle la perte d'autocontrôle est le prédicteur le plus sûr de tous les types de résistance. Les résultats soutiennent l'hypothèse voulant que, si le lien entre classe sociale (ou bien genre ou appartenance ethnique) et résistance est ténu (au Canada du moins), c'est peut-être parce que les mécanismes d'autocontrôle qui suscitent ou rejettent le phénomène de résistance ne sont pas intimement liés à la classe sociale (ou bien au genre ou à l'appartenance ethnique). Toutefois, le sexe, l'âge, la classe sociale et l'appartenance ethnique restent étroitement liés à certains ou à l'ensemble des aspects de la résistance au système scolaire même en présence d'autocontrôle. Les conclusions de la General Theory of Crime et leurs répercussions sont également abordées ici. This paper tests the relationship between self-control, social control and resistance to school. The data source is a survey of senior and junior high-school students in Alberta, Canada. Results offer strong support for the General Theory of Crime (Gottfredson and Hirschi, 1990) in that lack of self-control is the strongest predictor of all types of resistance. The results support the hypothesis that if the link between social class (or gender and ethnicity) and resistance is low (at least in Canada), it may be because self-control mechanisms that produce or repudiate resistance are not strongly linked to social class (or gender and ethnicity). Nevertheless, gender, age, class and ethnicity maintain a significant relationship with some or all aspects of resistance to school even after controlling for self-control. Implications of the findings for the General Theory of Crime are discussed. [source] General theory of domain decomposition: Indirect methodsNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 3 2002Ismael Herrera Abstract According to a general theory of domain decomposition methods (DDM), recently proposed by Herrera, DDM may be classified into two broad categories: direct and indirect (or Trefftz-Herrera methods). This article is devoted to formulate systematically indirect methods and apply them to differential equations in several dimensions. They have interest since they subsume some of the best-known formulations of domain decomposition methods, such as those based on the application of Steklov-Poincaré operators. Trefftz-Herrera approach is based on a special kind of Green's formulas applicable to discontinuous functions, and one of their essential features is the use of weighting functions which yield information, about the sought solution, at the internal boundary of the domain decomposition exclusively. A special class of Sobolev spaces is introduced in which boundary value problems with prescribed jumps at the internal boundary are formulated. Green's formulas applicable in such Sobolev spaces, which contain discontinuous functions, are established and from them the general framework for indirect methods is derived. Guidelines for the construction of the special kind of test functions are then supplied and, as an illustration, the method is applied to elliptic problems in several dimensions. A nonstandard method of collocation is derived in this manner, which possesses significant advantages over more standard procedures. © 2002 Wiley Periodicals, Inc. Numer Methods Partial Differential Eq 18: 296,322, 2002; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/num.10008 [source] General theory of domain decomposition: Beyond Schwarz methodsNUMERICAL METHODS FOR PARTIAL DIFFERENTIAL EQUATIONS, Issue 5 2001Ismael Herrera Abstract Recently, Herrera presented a general theory of domain decomposition methods (DDM). This article is part of a line of research devoted to its further development and applications. According to it, DDM are classified into direct and indirect, which in turn can be subdivided into overlapping and nonoverlapping. Some articles dealing with general aspects of the theory and with indirect (Trefftz,Herrera) methods have been published. In the present article, a very general direct-overlapping method, which subsumes Schwarz methods, is introduced. Also, this direct-overlapping method is quite suitable for parallel implementation. © 2001 John Wiley & Sons, Inc. Numer Methods Partial Differential Eq 17: 495,517, 2001 [source] Manifestly covariant classical correlation dynamics I. General theoryANNALEN DER PHYSIK, Issue 10-11 2009C. Tian Abstract In this series of papers we substantially extend investigations of Israel and Kandrup on nonequilibrium statistical mechanics in the framework of special relativity. This is the first one devoted to the general mathematical structure. Based on the action-at-a-distance formalism we obtain a single-time Liouville equation. This equation describes the manifestly covariant evolution of the distribution function of full classical many-body systems. For such global evolution the Bogoliubov functional assumption is justified. In particular, using the Balescu-Wallenborn projection operator approach we find that the distribution function of full many-body systems is completely determined by the reduced one-body distribution function. A manifestly covariant closed nonlinear equation satisfied by the reduced one-body distribution function is rigorously derived. We also discuss extensively the generalization to general relativity especially an application to self-gravitating systems. [source] Manifestly covariant classical correlation dynamics I. General theoryANNALEN DER PHYSIK, Issue 10-11 2009C. Tian Abstract In this series of papers we substantially extend investigations of Israel and Kandrup on nonequilibrium statistical mechanics in the framework of special relativity. This is the first one devoted to the general mathematical structure. Based on the action-at-a-distance formalism we obtain a single-time Liouville equation. This equation describes the manifestly covariant evolution of the distribution function of full classical many-body systems. For such global evolution the Bogoliubov functional assumption is justified. In particular, using the Balescu-Wallenborn projection operator approach we find that the distribution function of full many-body systems is completely determined by the reduced one-body distribution function. A manifestly covariant closed nonlinear equation satisfied by the reduced one-body distribution function is rigorously derived. We also discuss extensively the generalization to general relativity especially an application to self-gravitating systems. [source] Cerebral Cortical Gyrification: A Preliminary Investigation in Temporal Lobe EpilepsyEPILEPSIA, Issue 2 2007Lisa Ronan Summary:,Purpose: To introduce a measure of global cortical folding in epilepsy by using stereology. Subtle developmental abnormalities associated with temporal lobe epilepsy may encompass brain morphologic changes such as an aberrant degree of cortical folding. Methods: Stereologic methods of volume and surface-area estimation were applied to in vivo MR brain-image data of a cohort of 20 temporal lobe epilepsy (TLE) patients (10 men, 10 women), and 20 neurologically normal controls (10 men, 10 women). Indices of cerebral gyrification and cerebral atrophy were generated. The impact of side of seizure onset, age at onset, history of febrile seizures, presence or absence of lesions, and presence or absence of secondarily generalized seizures on cerebral gyrification was assessed. Results: Although no significant group mean difference was found in the degree of cerebral gyrification between patients and controls, five of 10 of male patients had an abnormal gyrification when compared with male controls. One female patient had a significant change in gyrification compared with female controls. In general, patients with TLE demonstrated a significant degree of global cerebral atrophy compared with controls. Clinical factors were not demonstrated to affect significantly any of the quantitative parameters. Conclusions: The results of this study suggest that an aberrant degree of global cerebral gyrification may occur in certain clinical groups of TLE patients. These findings have implications for general theories of developmental susceptibility in TLE. [source] Appraising, researching and conceptualizing criminal thinking: a personal viewCRIMINAL BEHAVIOUR AND MENTAL HEALTH, Issue 2 2006GLENN D. WALTERS Background,It is argued that current interest in the concept of criminal thinking has its roots in traditional theories of criminology and criminal justice such as Sutherland's differential association model, neutralization theory, and Yochelson and Samenow's criminal personality. Aim,The purpose of this paper is to briefly review and summarize theory, research, and practice on criminal thinking as it relates to the author's work in this area. Conclusions,Three self-report inventories , the Criminal Sentiments Scale (CSS), the Psychological Inventory of Criminal Thinking Styles (PICTS), and the Measures of Criminal Attitudes and Associates (MCAA); three principal areas of research , criminal thinking as a predictor of criminal behaviour, offence as a moderator of criminal thinking, and changes in criminal thinking leading to changes in criminal behaviour; and a general theory of criminal thinking are briefly reviewed in this paper. Copyright © 2006 John Wiley & Sons, Ltd. [source] A theory for elastic properties of single crystals with microstructure and its application to diffusion induced segregationCRYSTAL RESEARCH AND TECHNOLOGY, Issue 9 2008T. Blesgen Abstract In this article a general theory for elastically stressed single crystals in the presence of microstructure is presented and an explicit formula for the resulting non-linear stored mechanical energy is obtained. The optimal microstructure under applied stress is characterised and the optimal laminates are identified in 2D. The analysis is based on a sharp lower estimate of the energy that relies on relaxation. The new theory is then used to extend existing models for diffusion induced segregation (DIS) in the case of (Zn,Fe)S single crystals. Numerical simulations based on finite elements are carried out and the results are compared with former computations of the homogeneous case. (© 2008 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Sequential decision-theoretic models and expert systemsEXPERT SYSTEMS, Issue 2 2002Silvano Mussi Sequential decision models are an important component of expert systems since, in general, the cost of acquiring information is significant and there is a trade-off between the cost and the value of information. Many expert systems in various domains (business, engineering, medicine etc.), needing costly inputs that are not known until the system operates, have to face this problem. In the last decade the field of sequential decision models based on decision theory (sequential decision-theoretic models) have become more and more important due to both the continuous progress made by research in Bayesian networks and the availability of modern powerful tools for building Bayesian networks and for probability propagation. This paper provides readers (especially knowledge engineers and expert system designers) with a unified and integrated presentation of the disparate literature in the field of sequential decision-making based on decision theory, in order to improve comprehensibility and accessibility. Besides the presentation of the general theory, a view of sequential diagnosis as an instance of the general concept of sequential decision-theoretic models is also shown. [source] Linking ecological theory with stream restorationFRESHWATER BIOLOGY, Issue 4 2007P. S. LAKE Summary 1. Faced with widespread degradation of riverine ecosystems, stream restoration has greatly increased. Such restoration is rarely planned and executed with inputs from ecological theory. In this paper, we seek to identify principles from ecological theory that have been, or could be, used to guide stream restoration. 2. In attempts to re-establish populations, knowledge of the species' life history, habitat template and spatio-temporal scope is critical. In many cases dispersal will be a critical process in maintaining viable populations at the landscape scale, and special attention should be given to the unique geometry of stream systems 3. One way by which organisms survive natural disturbances is by the use of refugia, many forms of which may have been lost with degradation. Restoring refugia may therefore be critical to survival of target populations, particularly in facilitating resilience to ongoing anthropogenic disturbance regimes. 4. Restoring connectivity, especially longitudinal connectivity, has been a major restoration goal. In restoring lateral connectivity there has been an increasing awareness of the riparian zone as a critical transition zone between streams and their catchments. 5. Increased knowledge of food web structure , bottom-up versus top-down control, trophic cascades and subsidies , are yet to be applied to stream restoration efforts. 6. In restoration, species are drawn from the regional species pool. Having overcome dispersal and environmental constraints (filters), species persistence may be governed by local internal dynamics, which are referred to as assembly rules. 7. While restoration projects often define goals and endpoints, the succession pathways and mechanisms (e.g. facilitation) by which these may be achieved are rarely considered. This occurs in spite of a large of body of general theory on which to draw. 8. Stream restoration has neglected ecosystem processes. The concept that increasing biodiversity increases ecosystem functioning is very relevant to stream restoration. Whether biodiversity affects ecosystem processes, such as decomposition, in streams is equivocal. 9. Considering the spatial scale of restoration projects is critical to success. Success is more likely with large-scale projects, but they will often be infeasible in terms of the available resources and conflicts of interest. Small-scale restoration may remedy specific problems. In general, restoration should occur at the appropriate spatial scale such that restoration is not reversed by the prevailing disturbance regime. 10. The effectiveness and predictability of stream ecosystem restoration will improve with an increased understanding of the processes by which ecosystems develop and are maintained. Ideas from general ecological theory can clearly be better incorporated into stream restoration projects. This will provide a twofold benefit in providing an opportunity both to improve restoration outcomes and to test ecological theory. [source] On the generation of conjugate flanks for arbitrary gear geometriesGAMM - MITTEILUNGEN, Issue 1 2009A. Johann Abstract In this paper, we present a novel approach to three-dimensional mathematical gearing theory. We start from a general formulation of the so called basic law of gear kinematics. Based on that we derive an analytic closed form solution for the generation of conjugate tooth flanks, given a (local) parametric representation for any prescribed flank profile. Also, we study the problem of constructing pairs of tooth flanks that give rise to a prescribed surface of action. Surfaces of action will be represented in an implicit global rather than in a parametric way. To illustrate the general theory, we consider a number of specific examples including the standard involute profile for spur gears as well as a more sophisticated three-dimensional generalization of that (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] Elevation gradients of species-density: historical and prospective viewsGLOBAL ECOLOGY, Issue 1 2001MARK. V. Lomolino Abstract Studies of elevation clines in diversity and composition of ecological communities date back to the origins of biogeography. A modern resurgence of interests in these elevational clines is likely to contribute important insights for developing a more general theory of species diversity. In order to gain a more comprehensive understanding of geographical clines in diversity, the research programme for montane biogeography should include statistically rigorous tests of apparent patterns, comparisons of patterns among regions and taxonomic or ecological groups of species, and analyses of clines in environmental variables concurrent with biogeographical surveys. The conceptual framework for this research programme should be based on the assumption that elevational gradients in species diversity result from a combination of ecological and evolutionary processes, rather than the presumed independent effects of one overriding force. Given that montane ecosystems are hot spots of biological diversity, an expanded and integrated programme for biogeographic surveys in montane regions should provide valuable insights for conservation biologists. [source] The acceptance of systemic thinking in various fields of technology and consequences on the respective safety philosophiesHUMAN FACTORS AND ERGONOMICS IN MANUFACTURING & SERVICE INDUSTRIES, Issue 3 2003Willy Geysen Systemic thinking aims to develop a common language that makes it possible for scientists of different disciplines and technologies to communicate with one another. The specific methodology of systemic thinking is a means of tackling complex, interrelated problems by applying a holistic approach that focuses on the interrelation of individual aspects. In this article, an attempt is made to show the impact of systemic thinking in different areas of science and technology. In particular, the authors argue that a multidisciplinary, systemic approach can play an important role in developing a general theory of safety science. © 2003 Wiley Periodicals, Inc. Hum Factors Man 13: 231,242, 2003. [source] Disordered lattice networks: general theory and simulationsINTERNATIONAL JOURNAL OF CIRCUIT THEORY AND APPLICATIONS, Issue 6 2005Stefano GiordanoArticle first published online: 16 NOV 200 Abstract In this work we develop a theory for describing random networks of resistors of the most general topology. This approach generalizes and unifies several statistical theories available in literature. We consider an n-dimensional anisotropic random lattice where each node of the network is connected to a reference node through a given random resistor. This topology includes many structures of great interest both for theoretical and practical applications. For example, the one-dimensional systems correspond to random ladder networks, two-dimensional structures model films deposited on substrates and three-dimensional lattices describe random heterogeneous materials. Moreover, the theory is able to take into account the anisotropic percolation problem for two- and three-dimensional structures. The analytical results allow us to obtain the average behaviour of such networks, i.e. the electrical characterization of the corresponding physical systems. This effective medium theory is developed starting from the properties of the lattice Green's function of the network and from an ad hoc mean field procedure. An accurate analytical study of the related lattice Green's functions has been conducted obtaining many closed form results expressed in terms of elliptic integrals. All the theoretical results have been verified by means of numerical Monte-Carlo simulations obtaining a remarkably good agreement between numerical and theoretical values. Copyright © 2005 John Wiley & Sons, Ltd. [source] Toward a general theory of conditional beliefsINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 3 2006Giulianella Coletti We consider a class of general decomposable measures of uncertainty, which encompasses (as its most specific elements, with respect to the properties of the rules of composition) probabilities, and (as its most general elements) belief functions. The aim, using this general context, is to introduce (in a direct way) the concept of conditional belief function as a conditional generalized decomposable measure ,(·|·), defined on a set of conditional events. Our main tool will be the following result, that we prove in the first part of the article and which is a sort of converse of a well-known result (i.e., a belief function is a lower probability): a coherent conditional lower probability P(·|K) extending a coherent probability P(Hi),where the events His are a partition of the certain event , and K is the union of some (possibly all) of them,is a belief function. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 229,259, 2006. [source] Inverse problems in quantum chemistryINTERNATIONAL JOURNAL OF QUANTUM CHEMISTRY, Issue 11 2009Jacek Karwowski Abstract Inverse problems constitute a branch of applied mathematics with well-developed methodology and formalism. A broad family of tasks met in theoretical physics, in civil and mechanical engineering, as well as in various branches of medical and biological sciences has been formulated as specific implementations of the general theory of inverse problems. In this article, it is pointed out that a number of approaches met in quantum chemistry can (and should) be classified as inverse problems. Consequently, the methodology used in these approaches may be enriched by applying ideas and theorems developed within the general field of inverse problems. Several examples, including the RKR method for the construction of potential energy curves, determining parameter values in semiempirical methods, and finding external potentials for which the pertinent Schrödinger equation is exactly solvable, are discussed in detail. © 2009 Wiley Periodicals, Inc. Int J Quantum Chem, 2009 [source] A Bargaining Theory of Minority Demands: Explaining the Dog that Did not Bite in 1990s YugoslaviaINTERNATIONAL STUDIES QUARTERLY, Issue 4 2004Erin Jenne This article develops a general theory of bargaining between a minority, its host state, and outside lobby actor to explain why minorities shift their demands from affirmative action to cultural autonomy to secessionism and back, often in the absence of clear economic or security incentives. This paper uses a simple game tree model to show that if a minority believes that it enjoys significant support from a powerful national homeland or other external actor, it radicalized its demands against the host state, even if the center has credibly committed to protect minority rights. Conversely, if a minority believes that it enjoys no external support, then it will accommodate the host state, even in the presence of significant majority repression. As a general theory of claim-making, this model challenges structural theories of demands that rely on static economic differences or historical grievances to explain claim-making. It also challenges security dilemma arguments that hold that minority radicalization is mainly a function of ethnic fears. The model's hypotheses are tested using longitudinal analysis of Hungarians in Vojvodina during the 1990s, as the Yugoslav dog that "barked but did not bite." Careful examination of claim-making in this case demonstrates the superior explanatory power of the ethnic bargaining model as compared with dominant theories of minority mobilization in the literature. [source] Dynamics of regional coexistence for more or less equal competitorsJOURNAL OF ANIMAL ECOLOGY, Issue 1 2003C. Patrick Doncaster Summary 1Competition between two species in a metapopulation involves each inhibiting the other's ability firstly to colonize an already occupied area and then to persist in it. Models for regional competition of this kind have 3-D dynamics, from which it has proved difficult to extract useful predictions except for special conditions. We introduce a 2-D general model for species that are equally vigorous at inhibiting the ability of others to remain in an occupied patch as to arrive there. The model covers the full spectrum of competitive interactions, from weak to strong and symmetrical to asymmetrical. Its Lotka,Volterra dynamics extend the general theory of competitive coexistence by generating clear predictions for community structure, amenable to cross-system comparisons and experimental manipulations. 2Previous 2-D models of interactions between dominant and fugitive species are special cases of the 2-D general model. Moderately asymmetrical competition has two outcomes distinctly different from dominant,fugitive interactions, at both the scale of metapopulation and population: (i) slow growing and weak competitors coexist with faster growing superior competitors, albeit at reduced densities; and (b) habitat removal always yields relative gains in abundance for species with higher growth capacity, but the gains are absolute only for species subjected to competitive impacts that exceed within-species impacts. Extinctions of slow growing and weak competitors provide the most sensitive indication of habitat degradation, and their losses also have the least effect on community structure. 3The 2-D general model further predicts that highly productive communities will tolerate differences between species in their capacity for population growth, whereas less productive communities will tolerate stronger competitive interactions between species. This prediction applies equally to a population of resource consumers as to a metapopulation of colonists. The model explicitly links local and regional population dynamics to r,K selection in community structure by predicting a prevalence of growth-orientated species in resource-poor habitats and competition-orientated species in resource-rich habitats. [source] Scattering from laterally heterogeneous vesicles.JOURNAL OF APPLIED CRYSTALLOGRAPHY, Issue 3 2007Despite growing interest in the formation of domains or `rafts' in cell and model membranes, there have been relatively few attempts to characterize such systems via scattering techniques. Previously [Pencer et al. (2006). J. Appl. Cryst.39, 293,303], it was demonstrated that the Porod invariant, Q, could be used to detect lateral segregation. Here, the general theory for scattering from laterally heterogeneous vesicles is outlined and form factors are derived for vesicles containing either single circular or annular domains. These form factors are then applied to the analysis of neutron scattering data from heterogeneous vesicles. Potential advantages and limitations of this technique are also discussed. [source] Predicting avian patch occupancy in a fragmented landscape: do we know more than we think?JOURNAL OF APPLIED ECOLOGY, Issue 5 2009Danielle F. Shanahan Summary 1.,A recent and controversial topic in landscape ecology is whether populations of species respond to habitat fragmentation in a general fashion. Empirical research has provided mixed support, resulting in controversy about the use of general rules in landscape management. Rather than simply assessing post hoc whether individual species follow such rules, a priori testing could shed light on their accuracy and utility for predicting species response to landscape change. 2.,We aim to create an a priori model that predicts the presence or absence of multiple species in habitat patches. Our goal is to balance general theory with relevant species life-history traits to obtain high prediction accuracy. To increase the utility of this work, we aim to use accessible methods that can be applied using readily available inexpensive resources. 3.,The classification tree patch-occupancy model we create for birds is based on habitat suitability, minimum area requirements, dispersal potential of each species and overall landscape connectivity. 4.,To test our model we apply it to the South East Queensland region, Australia, for 17 bird species with varying dispersal potential and habitat specialization. We test the accuracy of our predictions using presence,absence information for 55 vegetation patches. 5.,Overall we achieve Cohen's kappa of 0·33, or ,fair' agreement between the model predictions and test data sets, and generally a very high level of absence prediction accuracy. Habitat specialization appeared to influence the accuracy of the model for different species. 6.,We also compare the a priori model to the statistically derived model for each species. Although this ,optimal model' generally differed from our original predictive model, the process revealed ways in which it could be improved for future attempts. 7.,Synthesis and applications. Our study demonstrates that ecological generalizations alongside basic resources (a vegetation map and some species-specific information) can provide conservative accuracy for predicting species occupancy in remnant vegetation patches. We show that the process of testing and developing models based on general rules could provide basic tools for conservation managers to understand the impact of current or planned landscape change on wildlife populations. [source] Space allocation in Melanophila knoteki knoteki (Reitt.) var. hellenica (Obenberger) (Col., Buprestidae) in the attack of Greek fir [Abies cephalonica Loud. var. graeca (Fraas) Liu]: a pattern to process approachJOURNAL OF APPLIED ENTOMOLOGY, Issue 1 2004P. V. Petrakis Abstract: The phloeo-cambiophagous buprestid Melanophila knoteki knoteki (Reitt.) var. hellenica (Obenberger.) is not a primary factor of fir decline problem although the beetle substantially contributes to Greek fir Abies cephalonica Loud. var. graeca (Fraas) Liu mortality. By using mapping depiction of the exit holes of the insect on a set of fir trees located on a line transect in a randomized point-centred quarter scheme and employing pattern analysis techniques we were able to reveal various scales of the infestation pattern. Four scales were recognized, two of them corresponding to the pattern of microsite selection on the bark of a fir tree. While the dispersed exit holes exhibited a statistically significant random dispersion on the bark, within each aggregation the pattern was uniform. The area of compartments created by Dirichlet partition approximated very well the sizes of the actual larval galleries. The Dirichlet tessellation of the bark space and the analysis of the parameter of the resulting partitions showed the predominance of the hexagonal conformation of the larval spaces when space was limited. When some exit holes were positioned close together it was found that they were directed away from each other so the resulting galleries were well separated. Several hypotheses are presented as to the mechanisms underpinning the observed patterns. The allocation of space is in accordance with the widely accepted ,central place theory' of W. Christaller, a general theory of pattern generated in the geographical dispersion of human settlements. The revealed pattern was also in accordance with the predictions of the theory of ,central place foraging' of R. H. MacArthur and the theory of ,resource concentration hypothesis' of R. Root. [source] The Golden Rule and the Potentiality Principle: Future Persons and Contingent InterestsJOURNAL OF APPLIED PHILOSOPHY, Issue 1 2004Kai M. A. Chan abstract,Duties to future persons are central to numerous key ethical issues including contraception, abortion, genetic selection, treatment of the environment, and population control. Nevertheless, we still seem to be lacking Parfit's ,Theory X', a general theory of beneficence whose appropriateness extends to future generations. Starting from the Golden Rule (TGR), R. M. Hare purportedly derived counterintuitive duties to potential people and ,the potentiality principle'. However, I argue that Hare's derivation involves a hidden and unjustifiable extension from TGR, and show how the most plausible form of TGR is compatible with multiple contradictory principles for the treatment of future persons. I appeal to our own preferences to argue that one extension of TGR follows the spirit of TGR, while the other is deeply implausible. Using the plausible extension, I derive a Contingent Interests Principle (CIP) that offers much promise as Parfit's elusive Theory X. In contrast to Hare's interpretation of TGR, this application provides solid justification for rejecting the potentiality principle. [source] A (Re)Conceived Feminist Paradigm for Public Relations: A Case for Substantial ImprovementJOURNAL OF COMMUNICATION, Issue 4 2005Linda Aldoory This article advances a feminist paradigm for public relations scholarship by (re)conceptualizing the concepts of gender, power, and diversity as discursive practices that construct the meaning of public relations. These three concepts are then applied to the body of work on organization-public relationships. The article posits that the current feminist paradigm retains androcentric bias. By transforming the way that the paradigm is practiced, general theory and knowledge are enriched. The reconceptualizations put forth in this article are useful for communication scholarship in general and can be used as a model for feminist research in other domains of communication. [source] Disasters, Lessons Learned, and Fantasy DocumentsJOURNAL OF CONTINGENCIES AND CRISIS MANAGEMENT, Issue 3 2009Thomas A. Birkland This article develops a general theory of why post-disaster ,lessons learned' documents are often ,fantasy documents'. The article describes the political and organizational barriers to effective learning from disasters, and builds on general theory building on learning from extreme events to explain this phenomenon. Fantasy documents are not generally about the ,real' causes and solutions to disasters; rather, they are generated to prove that some authoritative actor has ,done something' about a disaster. Because it is difficult to test whether learning happened after an extreme event, these post-disaster documents are generally ignored after they are published. [source] Mechanisms of pathogenesis and the evolution of parasite virulenceJOURNAL OF EVOLUTIONARY BIOLOGY, Issue 2 2008S. A. FRANK Abstract When studying how much a parasite harms its host, evolutionary biologists turn to the evolutionary theory of virulence. That theory has been successful in predicting how parasite virulence evolves in response to changes in epidemiological conditions of parasite transmission or to perturbations induced by drug treatments. The evolutionary theory of virulence is, however, nearly silent about the expected differences in virulence between different species of parasite. Why, for example, is anthrax so virulent, whereas closely related bacterial species cause little harm? The evolutionary theory might address such comparisons by analysing differences in tradeoffs between parasite fitness components: transmission as a measure of parasite fecundity, clearance as a measure of parasite lifespan and virulence as another measure that delimits parasite survival within a host. However, even crude quantitative estimates of such tradeoffs remain beyond reach in all but the most controlled of experimental conditions. Here, we argue that the great recent advances in the molecular study of pathogenesis provide a way forward. In light of those mechanistic studies, we analyse the relative sensitivity of tradeoffs between components of parasite fitness. We argue that pathogenic mechanisms that manipulate host immunity or escape from host defences have particularly high sensitivity to parasite fitness and thus dominate as causes of parasite virulence. The high sensitivity of immunomodulation and immune escape arise because those mechanisms affect parasite survival within the host, the most sensitive of fitness components. In our view, relating the sensitivity of pathogenic mechanisms to fitness components will provide a way to build a much richer and more general theory of parasite virulence. [source] | |||||||||||||||||||||||||||||||||||||