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Emergent Properties (emergent + property)
Selected Abstracts,A FACT WITHOUT PARALLEL': CONSCIOUSNESS AS AN EMERGENT PROPERTYBRITISH JOURNAL OF PSYCHOTHERAPY, Issue 1 2004David M. Black ABSTRACT Consciousness was described by Freud as,a fact without parallel'. This paper suggests that the attempts by modern psychology and neuroscience to understand consciousness have failed to appreciate that it lies for clear and necessary reasons beyond the reach of 'science'as we have understood it since the seventeenth century. The author goes on to argue that the fact of consciousness implies a world of subjectivity and uniqueness which will only be integrated with the world of empirical science if there can be profound changes in our understanding of science itself; or, alternatively, if clear bounds are recognized to science's domain. [source] Modular Inorganic Polyoxometalate Frameworks Showing Emergent Properties: Redox Alloys,ANGEWANDTE CHEMIE, Issue 39 2010Johannes Thiel Ein reines Cobalt-Keggin-Gerüst mit W-O-Co-Wechselwirkungen wurde mit einem reinen Mangan-Keggin-Gerüst mit W-O-Mn-Wechselwirkungen ,legiert". Die isostrukturellen Legierungen sind feste Lösungen der Co- und Mn-Netze. Eine Reihe einkristalliner gemischter Gerüste mit neuartigen Redoxeigenschaften wurde durch Mischen der Komponenten jedes einzelnen Übergangsmetallgerüsts im entsprechenden stöchiometrischen Verhältnis erhalten. [source] Computational Evidence for the Subitizing Phenomenon as an Emergent Property of the Human Cognitive ArchitectureCOGNITIVE SCIENCE - A MULTIDISCIPLINARY JOURNAL, Issue 1 2000Scott A. Peterson A computational modeling approach was used to test one possible explanation for the limited capacity of the subitizing phenomenon. Most existing models of this phenomenon associate the subitizing span with an assumed structural limitation of the human information processing system. In contrast, we show how this limit might emerge as the combinatorics of the space of enumeration problems interacts with the human cognitive architecture in the context of an enumeration task. Subitizing-like behavior was generated in two different models of enumeration, one based on the ACT-R cognitive architecture and the other based on the principles of parallel distributed processing (PDP). Our results provide good qualitative fits to results obtained in a variety of empirical studies. [source] The carrying capacity of ecosystemsGLOBAL ECOLOGY, Issue 6 2004Pablo Del Monte-Luna ABSTRACT We analyse the concept of carrying capacity (CC), from populations to the biosphere, and offer a definition suitable for any level. For communities and ecosystems, the CC evokes density-dependence assumptions analogous to those of population dynamics. At the biosphere level, human CC is uncertain and dynamic, leading to apprehensive rather than practical conclusions. The term CC is widely used among ecological disciplines but remains vague and elusive. We propose the following definition: the CC is ,the limit of growth or development of each and all hierarchical levels of biological integration, beginning with the population, and shaped by processes and interdependent relationships between finite resources and the consumers of those resources'. The restrictions of the concept relate to the hierarchical approach. Emergent properties arise at each level, and environmental heterogeneity restrains the measurement and application of the CC. Because the CC entails a myriad of interrelated, ever-changing biotic and abiotic factors, it must not be assumed constant, if we are to derive more effective and realistic management schemes. At the ecosystem level, stability and resilience are dynamic components of the CC. Historical processes that help shape global biodiversity (e.g. continental drift, glaciations) are likely drivers of large-scale changes in the earth's CC. Finally, world population growth and consumption of resources by humanity will necessitate modifications to the paradigm of sustainable development, and demand a clear and fundamental understanding of how CC operates across all biological levels. [source] Emergent properties from organisms to ecosystems: towards a realistic approachBIOLOGICAL REVIEWS, Issue 3 2005Jean-François Ponge ABSTRACT More realistic approaches are needed to understand the complexity of ecological systems. Emergent properties of real systems can be used as a basis for a new, neither reductionist nor holistic, approach. Three systems, termed here BUBBLEs, WAVEs and CRYSTALS, have been identified as exhibiting emergent properties. They are non-hierarchical assemblages of individual components, with amplification and connectedness being two main principles that govern their build-up, maintenance and mutual relationships. Examples from various fields of biological and ecological science are referred to, ranging from individual organisms to landscapes. [source] The physiology of rodent beta-cells in pancreas slicesACTA PHYSIOLOGICA, Issue 1 2009M. Rupnik Abstract Beta-cells in pancreatic islets form complex syncytia. Sufficient cell-to-cell electrical coupling seems to ensure coordinated depolarization pattern and insulin release that can be further modulated by rich innervation. The complex structure and coordinated action develop after birth during fast proliferation of the endocrine tissue. These emergent properties can be lost due to various reasons later in life and can lead to glucose intolerance and diabetes mellitus. Pancreas slice is a novel method of choice to study the physiology of beta-cells still embedded in their normal cellulo-social context. I present major advantages, list drawbacks and provide an overview on recent advances in our understanding of the physiology of beta-cells using the pancreas slice approach. [source] Meta-ecosystems: a theoretical framework for a spatial ecosystem ecologyECOLOGY LETTERS, Issue 8 2003Michel Loreau Abstract This contribution proposes the meta-ecosystem concept as a natural extension of the metapopulation and metacommunity concepts. A meta-ecosystem is defined as a set of ecosystems connected by spatial flows of energy, materials and organisms across ecosystem boundaries. This concept provides a powerful theoretical tool to understand the emergent properties that arise from spatial coupling of local ecosystems, such as global source,sink constraints, diversity,productivity patterns, stabilization of ecosystem processes and indirect interactions at landscape or regional scales. The meta-ecosystem perspective thereby has the potential to integrate the perspectives of community and landscape ecology, to provide novel fundamental insights into the dynamics and functioning of ecosystems from local to global scales, and to increase our ability to predict the consequences of land-use changes on biodiversity and the provision of ecosystem services to human societies. [source] Allometric scaling of maximum population density: a common rule for marine phytoplankton and terrestrial plantsECOLOGY LETTERS, Issue 5 2002Andrea Belgrano A primary goal of macroecology is to identify principles that apply across varied ecosystems and taxonomic groups. Here we show that the allometric relationship observed between maximum abundance and body size for terrestrial plants can be extended to predict maximum population densities of marine phytoplankton. These results imply that the abundance of primary producers is similarly constrained in terrestrial and marine systems by rates of energy supply as dictated by a common allometric scaling law. They also highlight the existence of general mechanisms linking rates of individual metabolism to emergent properties of ecosystems. [source] AMPA and metabotropic glutamate receptors cooperatively generate inspiratory-like depolarization in mouse respiratory neurons in vitroEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 12 2008Ryland W. Pace Abstract Excitatory transmission mediated by AMPA receptors is critical for respiratory rhythm generation. However, the role of AMPA receptors has not been fully explored. Here we tested the functional role of AMPA receptors in inspiratory neurons of the neonatal mouse preBötzinger complex (preBötC) using an in vitro slice model that retains active respiratory function. Immediately before and during inspiration, preBötC neurons displayed envelopes of depolarization, dubbed inspiratory drive potentials, that required AMPA receptors but largely depended on the Ca2+ -activated non-specific cation current (ICAN). We showed that AMPA receptor-mediated depolarization opened voltage-gated Ca2+ channels to directly evoke ICAN. Inositol 1,4,5-trisphosphate receptor-mediated intracellular Ca2+ release also evoked ICAN. Inositol 1,4,5-trisphosphate receptors acted downstream of group I metabotropic glutamate receptor activity but, here too, AMPA receptor-mediated Ca2+ influx was essential to trigger the metabotropic glutamate receptor contribution to inspiratory drive potential generation. This study helps to elucidate the role of excitatory transmission in respiratory rhythm generation in vitro. AMPA receptors in preBötC neurons initiate convergent signaling pathways that evoke post-synaptic ICAN, which underlies inspiratory drive potentials. The coupling of AMPA receptors with ICAN suggests that latent burst-generating intrinsic conductances are recruited by excitatory synaptic interactions among preBötC neurons in the context of respiratory network activity in vitro, exemplifying a rhythmogenic mechanism based on emergent properties of the network. [source] Past success and convergent thinking in groups: The role of group-focused attributionsEUROPEAN JOURNAL OF SOCIAL PSYCHOLOGY, Issue 4 2004Jack A. Goncalo Past success often causes groups to think narrowly around strategies that have worked in the past, even when environmental change has rendered these strategies ineffective. From a psychological perspective, this research seems to indicate that past success may give rise to convergent thinking in groups. Why might successful groups be prone to convergent thinking? I argue that the relationship between past success and convergent thinking may depend on the attributions that groups generate to explain their shared success. In this paper, I focus on two distinct attributions at the group level: Individual-focused attributions that reflect the idiosyncratic characteristics of individual group members and group-focused attributions that reflect the emergent properties of the group as a whole. I found that group-focused attributions for past success cause groups to generate fewer ideas that are, on average, more convergent. In contrast, individual-focused attributions cause groups to generate more ideas that are on average more divergent. These findings suggest that the experience of success may actually stimulate divergent thinking depending on how a group chooses to explain it. Copyright © 2004 John Wiley & Sons, Ltd. [source] Potential clinical relevance of the ,little brain' on the mammalian heartEXPERIMENTAL PHYSIOLOGY, Issue 2 2008J. A. Armour It is hypothetized that the heart possesses a nervous system intrinsic to it that represents the final relay station for the co-ordination of regional cardiac indices. This ,little brain' on the heart is comprised of spatially distributed sensory (afferent), interconnecting (local circuit) and motor (adrenergic and cholinergic efferent) neurones that communicate with others in intrathoracic extracardiac ganglia, all under the tonic influence of central neuronal command and circulating catecholamines. Neurones residing from the level of the heart to the insular cortex form temporally dependent reflexes that control overlapping, spatially determined cardiac indices. The emergent properties that most of its components display depend primarily on sensory transduction of the cardiovascular milieu. It is further hypothesized that the stochastic nature of such neuronal interactions represents a stabilizing feature that matches cardiac output to normal corporal blood flow demands. Thus, with regard to cardiac disease states, one must consider not only cardiac myocyte dysfunction but also the fact that components within this neuroaxis may interact abnormally to alter myocyte function. This review emphasizes the stochastic behaviour displayed by most peripheral cardiac neurones, which appears to be a consequence of their predominant cardiac chemosensory inputs, as well as their complex functional interconnectivity. Despite our limited understanding of the whole, current data indicate that the emergent properties displayed by most neurones comprising the cardiac neuroaxis will have to be taken into consideration when contemplating the targeting of its individual components if predictable, long-term therapeutic benefits are to accrue. [source] Soft ontologies, spatial representations and multi-perspective explorabilityEXPERT SYSTEMS, Issue 5 2008Mauri Kaipainen Abstract: It is against the dynamically evolving nature of many contemporary media applications to be analysed in terms of conventional rigid ontologies that rely on expertise-based fixed categories and hierarchical structure. Many of these rely on sharing ,folksonomies', personal descriptions of information and objects for one's own retrieval. Such applications involve many feedback mechanisms via the community, and have been shown to have emergent properties of complex dynamic systems. We propose that such dynamically evolving information domains can be more usefully described by means of a soft ontology, a dynamically flexible and inherently spatial metadata approach for ill-defined domains. Our contribution is (1) the elaboration of the so far intuitive concept of soft ontology in a way that supports conceptualizing dynamically evolving domains. Further, our approach proposes (2) a whole new mode of interaction with information domains by means of recurring exploration of an information domain from multiple perspectives in search of more comprehensive understanding of it, i.e. multi-perspective exploration. We demonstrate this concept with an example of collaborative tagging in an educational context. [source] The mechanism of emergenesisGENES, BRAIN AND BEHAVIOR, Issue 4 2006D. T. Lykken Since each individual produced by the sexual process contains a unique set of genes, very exceptional combinations of genes are unlikely to appear twice even within the same family. E. O. Wilson (1978) The intraclass correlations of monozygotic twins who were separated in infancy and reared apart (MZA twins) provide estimates of trait heritability, and the Minnesota Study of Twins Reared Apart [MISTRA: Bouchard et al. (1990), The sources of human psychological differences: the Minnesota study of twins reared apart, Science 250, 223,228] has demonstrated that MZA pairs are as similar in most respects as MZ pairs reared together. Some polygenic traits,e.g. stature, IQ, harm avoidance, negative emotionality, interest in sports,are polygenic-additive, so pairs of relatives resemble one another on the given trait in proportion to their genetic similarity. But the existence and the intensity of other important psychological traits seem to be emergent properties of gene configurations (or configurations of independent and partially genetic traits) that interact multiplicatively rather than additively. Monozygotic (MZ) twins may be strongly correlated on such emergenic traits, while the similarity of dizygotic (DZ) twins, sibs or parent,offspring pairs may be much less than half that of MZ pairs. Some emergenic traits, although strongly genetic, do not appear to run in families. MISTRA has provided at least two examples of traits for which MZA twins are strongly correlated, and DZA pairs correlate near zero, while DZ pairs reared together (DZTs) are about half as similar as MZTs. These findings suggest that even more traits may be emergenic than those already identified. Studies of adoptees reared together (who are perhaps more common than twins reared apart) may help to identify traits that are emergenic, but that also are influenced by a common rearing environment. [source] Transnational communities and business systemsGLOBAL NETWORKS, Issue 2 2001Glenn Morgan The paper examines the concept of ,transnational communities' as a way of understanding globalization practices in business and management. It argues that ,transnational communities' are emergent properties of the internationalizing of economic activity. Three specific aspects of this process are considered in detail: the development of multinational companies; the development of international regulatory bodies; and the development of cognitive and normative frameworks through the practices of business education, management consultancies and other global professional service firms. It is argued that in each case, transnational spaces are emerging; within these spaces, transnational communities are developing. The article calls for more research into the diverse nature of these spaces and communities as a way of avoiding the sterile polarities of what Held et al. (1999) refer to as the ,hyperglobalists' and the ,sceptics'. [source] Introduction: Second Language Development as a Dynamic ProcessMODERN LANGUAGE JOURNAL, Issue 2 2008KEES DE BOT In this contribution, some of the basic characteristics of complex adaptive systems, collectively labeled Dynamic Systems Theory (DST), are discussed. Such systems are self-organizing, dependent on initial conditions, sometimes chaotic, and they show emergent properties. The focus in DST is on development over time. Language is seen as a dynamic system, and language development, both acquisition and attrition, as a dynamic process. A number of examples of possible applications of DST in the field of applied linguistics are mentioned. After a short presentation of each of the individual articles, some possible lines of research are discussed. [source] SOFTWARE ENGINEERING CONSIDERATIONS FOR INDIVIDUAL-BASED MODELSNATURAL RESOURCE MODELING, Issue 1 2002GLEN E. ROPELLA ABSTRACT. Software design is much more important for individual-based models (IBMs) than it is for conventional models, for three reasons. First, the results of an IBM are the emergent properties of a system of interacting agents that exist only in the software; unlike analytical model results, an IBMs outcomes can be reproduced only by exactly reproducing its software implementation. Second, outcomes of an IBM are expected to be complex and novel, making software errors difficult to identify. Third, an IBM needs ,systems software' that manages populations of multiple kinds of agents, often has nonlinear and multi-threaded process control and simulates a wide range of physical and biological processes. General software guidelines for complex models are especially important for IBMs. (1) Have code critically reviewed by several people. (2) Follow prudent release management prac-tices, keeping careful control over the software as changes are implemented. (3) Develop multiple representations of the model and its software; diagrams and written descriptions of code aid design and understanding. (4) Use appropriate and widespread software tools which provide numerous major benefits; coding ,from scratch' is rarely appropriate. (5) Test the software continually, following a planned, multi-level, exper-imental strategy. (6) Provide tools for thorough, pervasive validation and verification. (7) Pay attention to how pseudorandom numbers are generated and used. Additional guidelines for IBMs include: (a) design the model's organization before starting to write code,(b) provide the ability to observe all parts of the model from the beginning,(c) make an extensive effort to understand how the model executes how often different pieces of code are called by which objects, and (d) design the software to resemble the system being mod-eled, which helps maintain an understanding of the software. Strategies for meeting these guidelines include planning adequate resources for software development, using software professionals to implement models and using tools like Swarm that are designed specifically for IBMs. [source] Phytochromes, Cryptochromes, Phototropin: Photoreceptor Interactions in PlantsPHOTOCHEMISTRY & PHOTOBIOLOGY, Issue 1 2000Jorge J. Casal ABSTRACT In higher plants, natural radiation simultaneously activates more than one photoreceptor. Five phytochromes (phyA through phyD), two cryptochromes (cry1, cry2) and phototropin have been identified in the model species Arabidopsis thaliana. There is light-dependent epistasis among certain photoreceptor genes because the action of one pigment can be affected by the activity of others. Under red light, phyA and phyB are antagonistic, but under far-red light, followed by brief red light, phyA and phyB are synergistic in the control of seedling morphology and the expression of some genes during de-etiolation. Under short photoperiods of red and blue light, cry1 and phyB are synergistic, but under continuous exposure to the same light field the actions of phyB and cry1 become independent and additive. Phototropic bending of the shoot toward unilateral blue light is mediated by phototropin, but cry1, cry2, phyA and phyB positively regulate the response. Finally, cry2 and phyB are antagonistic in the induction of flowering. At least some of these interactions are likely to result from cross talk of the photoreceptor signaling pathways and uncover new avenues to approach signal transduction. Experiments under natural radiation are beginning to show that the interactions create a phototransduction network with emergent properties. This provides a more robust system for light perception in plants. [source] Entering, and returning from, the underworld: reconstituting Silbury Hill by combining a quantified landscape phenomenology with archaeoastronomyTHE JOURNAL OF THE ROYAL ANTHROPOLOGICAL INSTITUTE, Issue 2 2009Lionel Sims Landscape phenomenology limits the number of possible narratives for interpreting prehistoric monuments through the embodied experience of walking their remains in their landscape. While this method may improve upon an archaeology that narrows interpretation to single site excavations isolated in Euclidean space, it has been criticized for deploying unsubstantiated metaphors as an interpretative resource. Contemporary archaeoastronomy's dominant methodology submits regional groups of prehistoric monuments to rigorous statistical methods for testing whether perceived alignments were in fact intended by their builders. However, it is presently unable to saturate alignment findings with meaning, and reaches its limits when monuments are found to align on local landscape features rather than ,astronomical' bodies. Through a detailed examination of Silbury Hill in its landscape and late Neolithic/Early Bronze Age monument context, this article shows that problems in both methods can be transcended by studying the emergent properties generated by their combination. These emergent properties are consistent with the predictions of a recent anthropological model of lunar-solar conflation. Résumé La phénoménologie du paysage limite le nombre d'interprétations possibles des vestiges préhistoriques à celle obtenue par l'expérience vécue d'un arpentage dans leurs alentours. Bien que cette méthode puisse enrichir l'archéologie, qui restreint l'interprétation aux seules fouilles du site isolé dans l'espace euclidien, elle est critiquée pour l'usage de métaphores infondées comme sources d'interprétation. Par ailleurs, la méthodologie dominante de l'archéoastronomie contemporaine consiste à appliquer à des groupes régionaux de monuments préhistoriques des méthodes statistiques rigoureuses pour vérifier si les alignements perçus avaient effectivement été projetés par leurs constructeurs. Elle ne peut cependant pas saturer de signification les alignements retrouvés et atteint ses limites quand les monuments s'avèrent alignés sur des repères locaux du paysage plutôt que sur des corps « astronomiques ». À travers un examen détaillé de Silbury Hill dans son paysage et dans son contexte monumental du Néolithique et du Bronze ancien, l'article montre que les points faibles des deux méthodes peuvent être transcendés si l'on étudie les propriétés émergentes nées de leur combinaison. Ces nouvelles propriétés sont cohérentes avec les prédictions récentes d'un modèle anthropologique de rapprochement entre temps lunaire et temps solaire. [source] Emergent properties from organisms to ecosystems: towards a realistic approachBIOLOGICAL REVIEWS, Issue 3 2005Jean-François Ponge ABSTRACT More realistic approaches are needed to understand the complexity of ecological systems. Emergent properties of real systems can be used as a basis for a new, neither reductionist nor holistic, approach. Three systems, termed here BUBBLEs, WAVEs and CRYSTALS, have been identified as exhibiting emergent properties. They are non-hierarchical assemblages of individual components, with amplification and connectedness being two main principles that govern their build-up, maintenance and mutual relationships. Examples from various fields of biological and ecological science are referred to, ranging from individual organisms to landscapes. [source] Dynamic Chemical Instabilities in Living Cells May Provide a Novel Route in Drug DevelopmentCHEMBIOCHEM, Issue 10 2004Howard R. Petty Dr. Chemical waves, such as the NAD(P)H (green) and Ca2+(white-orange) waves of neutrophils, are emergent properties of living cells that represent the collective behavior of proteins that constitute intracellular subsystems. Studies of these waves suggest novel approaches in drug development and fresh insights into several clinical issues. [source] Visual response augmentation in cat (and macaque) LGN: potentiation by corticofugally mediated gain control in the temporal domainEUROPEAN JOURNAL OF NEUROSCIENCE, Issue 4 2000Javier Cudeiro Abstract Visual responses of neurons are dependent on the context of a stimulus, not only in spatial terms but also temporally, although evidence for temporally separate visual influences is meagre, based mainly on studies in the higher cortex. Here we demonstrate temporally induced elevation of visual responsiveness in cells in the lateral geniculate nucleus (LGN) of cat and monkey following a period of high intensity (elevated contrast) stimulation. This augmentation is seen in 40,70% (monkey,cat) of cells tested and of all subtypes. Peaking at ,,3 min following the period of intense stimulation, it can last for 10,12 min and can be repeated and summed in time. Furthermore, it is dependent on corticofugal input, is seen even when high contrast stimuli of orthogonal orientation are used and therefore results from a/any prior increase in activity in the retino-geniculo-striate pathway. We suggest that this reflects a general mechanism for control of visual responsiveness; both a flexible and dynamic means of changing effectiveness of thalamic activity as visual input changes, but also a mechanism which is an emergent property of the thalamo-cortico-thalamic loop. [source] Phosphate metabolite concentrations and ATP hydrolysis potential in normal and ischaemic heartsTHE JOURNAL OF PHYSIOLOGY, Issue 17 2008Fan Wu To understand how cardiac ATP and CrP remain stable with changes in work rate , a phenomenon that has eluded mechanistic explanation for decades , data from 31phosphate-magnetic resonance spectroscopy (31P-MRS) are analysed to estimate cytoplasmic and mitochondrial phosphate metabolite concentrations in the normal state, during high cardiac workstates, during acute ischaemia and reactive hyperaemic recovery. Analysis is based on simulating distributed heterogeneous oxygen transport in the myocardium integrated with a detailed model of cardiac energy metabolism. The model predicts that baseline myocardial free inorganic phosphate (Pi) concentration in the canine myocyte cytoplasm , a variable not accessible to direct non-invasive measurement , is approximately 0.29 mm and increases to 2.3 mm near maximal cardiac oxygen consumption. During acute ischaemia (from ligation of the left anterior descending artery) Pi increases to approximately 3.1 mm and ATP consumption in the ischaemic tissue is reduced quickly to less than half its baseline value before the creatine phosphate (CrP) pool is 18% depleted. It is determined from these experiments that the maximal rate of oxygen consumption of the heart is an emergent property and is limited not simply by the maximal rate of ATP synthesis, but by the maximal rate at which ATP can be synthesized at a potential at which it can be utilized. The critical free energy of ATP hydrolysis for cardiac contraction that is consistent with these findings is approximately ,63.5 kJ mol,1. Based on theoretical findings, we hypothesize that inorganic phosphate is both the primary feedback signal for stimulating oxidative phosphorylation in vivo and also the most significant product of ATP hydrolysis in limiting the capacity of the heart to hydrolyse ATP in vivo. Due to the lack of precise quantification of Piin vivo, these hypotheses and associated model predictions remain to be carefully tested experimentally. [source] | |||||||||||||||||||||||||||||||