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Generality
Selected AbstractsGenerality with specificity: the dynamic field theory generalizes across tasks and time scalesDEVELOPMENTAL SCIENCE, Issue 4 2008Vanessa R. Simmering A central goal in cognitive and developmental science is to develop models of behavior that can generalize across both tasks and development while maintaining a commitment to detailed behavioral prediction. This paper presents tests of one such model, the Dynamic Field Theory (DFT). The DFT was originally proposed to capture delay-dependent biases in spatial recall and developmental changes in spatial recall performance. More recently, the theory was generalized to adults' performance in a second spatial working memory task, position discrimination. Here we use the theory to predict a specific, complex developmental pattern in position discrimination. Data with 3- to 6-year-old children and adults confirm these predictions, demonstrating that the DFT achieves generality across tasks and time scales, as well as the specificity necessary to generate novel, falsifiable predictions. [source] Generality of vertebrate developmental patterns: evidence for a dermomyotome in fishEVOLUTION AND DEVELOPMENT, Issue 1 2006S. H. Devoto SUMMARY The somitic compartment that gives rise to trunk muscle and dermis in amniotes is an epithelial sheet on the external surface of the somite, and is known as the dermomyotome. However, despite its central role in the development of the trunk and limbs, the evolutionary history of the dermomyotome and its role in nonamniotes is poorly understood. We have tested whether a tissue with the morphological and molecular characteristics of a dermomyotome exists in nonamniotes. We show that representatives of the agnathans and of all major clades of gnathostomes each have a layer of cells on the surface of the somite, external to the embryonic myotome. These external cells do not show any signs of terminal myogenic or dermogenic differentiation. Moreover, in the embryos of bony fishes as diverse as sturgeons (Chondrostei) and zebrafish (Teleostei) this layer of cells expresses the pax3 and pax7 genes that mark myogenic precursors. Some of the pax7- expressing cells also express the differentiation-promoting myogenic regulatory factor Myogenin and appear to enter into the myotome. We therefore suggest that the dermomyotome is an ancient and conserved structure that evolved prior to the last common ancestor of all vertebrates. The identification of a dermomyotome in fish makes it possible to apply the powerful cellular and genetic approaches available in zebrafish to the understanding of this key developmental structure. [source] Evaluation of six process-based forest growth models using eddy-covariance measurements of CO2 and H2O fluxes at six forest sites in EuropeGLOBAL CHANGE BIOLOGY, Issue 3 2002K. Kramer Abstract Reliable models are required to assess the impacts of climate change on forest ecosystems. Precise and independent data are essential to assess this accuracy. The flux measurements collected by the EUROFLUX project over a wide range of forest types and climatic regions in Europe allow a critical testing of the process-based models which were developed in the LTEEF project. The ECOCRAFT project complements this with a wealth of independent plant physiological measurements. Thus, it was aimed in this study to test six process-based forest growth models against the flux measurements of six European forest types, taking advantage of a large database with plant physiological parameters. The reliability of both the flux data and parameter values itself was not under discussion in this study. The data provided by the researchers of the EUROFLUX sites, possibly with local corrections, were used with a minor gap-filling procedure to avoid the loss of many days with observations. The model performance is discussed based on their accuracy, generality and realism. Accuracy was evaluated based on the goodness-of-fit with observed values of daily net ecosystem exchange, gross primary production and ecosystem respiration (gC m,2 d,1), and transpiration (kg H2O m,2 d,1). Moreover, accuracy was also evaluated based on systematic and unsystematic errors. Generality was characterized by the applicability of the models to different European forest ecosystems. Reality was evaluated by comparing the modelled and observed responses of gross primary production, ecosystem respiration to radiation and temperature. The results indicated that: Accuracy. All models showed similar high correlation with the measured carbon flux data, and also low systematic and unsystematic prediction errors at one or more sites of flux measurements. The results were similar in the case of several models when the water fluxes were considered. Most models fulfilled the criteria of sufficient accuracy for the ability to predict the carbon and water exchange between forests and the atmosphere. Generality. Three models of six could be applied for both deciduous and coniferous forests. Furthermore, four models were applied both for boreal and temperate conditions. However, no severe water-limited conditions were encountered, and no year-to-year variability could be tested. Realism. Most models fulfil the criterion of realism that the relationships between the modelled phenomena (carbon and water exchange) and environment are described causally. Again several of the models were able to reproduce the responses of measurable variables such as gross primary production (GPP), ecosystem respiration and transpiration to environmental driving factors such as radiation and temperature. Stomatal conductance appears to be the most critical process causing differences in predicted fluxes of carbon and water between those models that accurately describe the annual totals of GPP, ecosystem respiration and transpiration. As a conclusion, several process-based models are available that produce accurate estimates of carbon and water fluxes at several forest sites of Europe. This considerable accuracy fulfils one requirement of models to be able to predict the impacts of climate change on the carbon balance of European forests. However, the generality of the models should be further evaluated by expanding the range of testing over both time and space. In addition, differences in behaviour between models at the process level indicate requirement of further model testing, with special emphasis on modelling stomatal conductance realistically. [source] Generality, Efficiency, and Neutrality: Must Laws be General to be Legitimate?PACIFIC PHILOSOPHICAL QUARTERLY, Issue 1 2001Zev Trachtenberg First page of article [source] Assembly rules and community models for unicellular organisms: patterns in diatoms of boreal streamsFRESHWATER BIOLOGY, Issue 4 2005JANI HEINO Summary 1. Many studies have addressed either community models (e.g. Clementsian versus Gleasonian gradients) or assembly rules (e.g. nestedness, checkerboards) for higher plant and animal communities, but very few studies have examined different non-random distribution patterns simultaneously with the same data set. Even fewer studies have addressed generalities in the distribution patterns of unicellular organisms, such as diatoms. 2. We studied non-randomness in the spatial distribution and community composition of stream diatoms. Our data consisted of diatom surveys from 47 boreal headwater streams and small rivers in northern Finland. Our analytical approaches included ordinations, cluster analysis, null model analyses, and associated randomisation tests. 3. Stream diatom communities did not follow discrete Clementsian community types, where multiple species occur exclusively in a single community type. Rather, diatom species showed rather individualistic responses, leading to continuous Gleasonian variability in community composition. 4. Although continuous variability was the dominating pattern in the data, diatoms also showed significant nestedness and less overlap in species distribution than expected by chance. However, these patterns were probably only secondary signals from species' individualistic responses to the environment. 5. Although unicellular organisms, such as diatoms, differ from multicellular organisms in several biological characteristics, they nevertheless appear to show largely similar non-random distribution patterns previously found for higher plants and metazoans. [source] Incipient speciation of Catostylus mosaicus (Scyphozoa, Rhizostomeae, Catostylidae), comparative phylogeography and biogeography in south-east AustraliaJOURNAL OF BIOGEOGRAPHY, Issue 3 2005Michael N Dawson Abstract Aim, Phylogeography provides a framework to explain and integrate patterns of marine biodiversity at infra- and supra-specific levels. As originally expounded, the phylogeographic hypotheses are generalities that have limited discriminatory power; the goal of this study is to generate and test specific instances of the hypotheses, thereby better elucidating both local patterns of evolution and the conditions under which the generalities do or do not apply. Location, Coastal south-east Australia (New South Wales, Tasmania and Victoria), and south-west North America (California and Baja California). Methods, Phylogeographic hypotheses specific to coastal south-east Australia were generated a priori, principally from existing detailed distributional analyses of echinoderms and decapods. The hypotheses are tested using mitochondrial cytochrome c oxidase subunit I (COI) and nuclear internal transcribed spacer 1 (ITS1) DNA sequence data describing population variation in the jellyfish Catostylus mosaicus, integrated with comparable data from the literature. Results, Mitochondrial COI distinguished two reciprocally monophyletic clades of C. mosaicus (mean ± SD: 3.61 ± 0.40% pairwise sequence divergence) that were also differentiated by ITS1 haplotype frequency differences; the boundary between the clades was geographically proximate to a provincial zoogeographic boundary in the vicinity of Bass Strait. There was also limited evidence of another genetic inhomogeneity, of considerably smaller magnitude, in close proximity to a second hypothesized zoogeographic discontinuity near Sydney. Other coastal marine species also show genetic divergences in the vicinity of Bass Strait, although they are not closely concordant with each other or with reported biogeographic discontinuities in the region, being up to several hundreds of kilometres apart. None of the species studied to date show a strong phylogeographic discontinuity across the biogeographic transition zone near Sydney. Main conclusions, Patterns of evolution in the Bass Strait and coastal New South Wales regions differ fundamentally because of long-term differences in extrinsic factors. Since the late Pliocene, periods of cold climate and low sea-level segregated warm temperate organisms east or west of an emergent Bassian Isthmus resulting in population divergence and speciation; during subsequent periods of warmer and higher seas, sister taxa expanded into the Bass Strait region leading to weakly correlated phylogeographic and biogeographic patterns. The Sydney region, by contrast, has been more consistently favourable to shifts in species' ranges and long-distance movement, resulting in a lack of intra-specific and species-level diversification. Comparisons between the Sydney and Bass Strait regions and prior studies in North America suggest that vicariance plays a key role in generating coastal biodiversity and that dispersal explains many of the deviations from the phylogeographic hypotheses. [source] Prediction and verification of possible reef-fish spawning aggregation sites in Los Roques Archipelago National Park, VenezuelaJOURNAL OF FISH BIOLOGY, Issue 4 2010J. Boomhower This study attempts to predict and verify possible spawning aggregation sites and times in the Los Roques Archipelago National Park, Venezuela, based on physical reef characteristics and the knowledge of experienced local fishermen. Three possible aggregation sites were selected for monitoring based on satellite images, low-cost bathymetric mapping and interviews with experienced local fishermen. Abundances and sizes of 18 species that are known to form reproductive aggregations were monitored at these sites using underwater visual census for 7 days after each full moon from February to August, 2007. While spawning events were not observed, possible indirect evidence of spawning aggregations was found for Lutjanus analis at Cayo Sal and Boca de Sebastopol, Lutjanus apodus at Cayo Sal, Lutjanus cyanopterus at Cayo Sal and Piedra La Guasa and Epinephelus guttatus at Bajo California and Cayo de Agua. Additionally, indirect evidence was identified for the past existence of a spawning aggregation of Epinephelus striatus in the northern part of the archipelago, which may have been eliminated by overfishing c.15 years ago. Bathymetric mapping showed that the shelf edge at sites monitored in this study was shallower than at spawning aggregation sites in other parts of the Caribbean, and that sites were not proximal to deep water. While this study does not prove the existence or locations of spawning aggregations of reef fishes in the archipelago, it does add insight to a growing understanding of generalities in the relationship between seafloor characteristics and the locations of transient reef-fish spawning aggregations in the Caribbean. [source] Clerking for Justice SouterJOURNAL OF SUPREME COURT HISTORY, Issue 1 2010HEATHER GERKEN Adam Gopnik once observed that "Paris is a struggle between its pompous official culture and its matchless , commonplace civilization." The aphorism applies even more clearly to the Supreme Court. It is an institution cloaked in formality, from the ceremonies of First Monday to the grand generalities it invokes in its ruling. It is also an institution that takes itself extremely seriously, with its strongest opinions penned when it thinks another institution,Congress in passing Commerce Clause legislation or the Religious Freedom Restoration Act, the Florida supreme court during,Bush v. Gore,is treading on the Court's privileges. The Court's pompous officious culture contributes to the studied cynicism lawyers exhibit whenever they talk about judges. [source] How do helix,helix interactions help determine the folds of membrane proteins?PROTEIN SCIENCE, Issue 4 2003Perspectives from the study of homo-oligomeric helical bundles FRET, fluorescence resonance energy transfer; NBD, 7-nitrobenz-2-oxa-1,3-diazole; C-14 betaine, N -tetradecyl- N,N -dimethyl-3-ammonio-1-propanesulfonate; MF, mole fraction Abstract The final, structure-determining step in the folding of membrane proteins involves the coalescence of preformed transmembrane helices to form the native tertiary structure. Here, we review recent studies on small peptide and protein systems that are providing quantitative data on the interactions that drive this process. Gel electrophoresis, analytical ultracentrifugation, and fluorescence resonance energy transfer (FRET) are useful methods for examining the assembly of homo-oligomeric transmembrane helical proteins. These methods have been used to study the assembly of the M2 proton channel from influenza A virus, glycophorin, phospholamban, and several designed membrane proteins,all of which have a single transmembrane helix that is sufficient for association into a transmembrane helical bundle. These systems are being studied to determine the relative thermodynamic contributions of van der Waals interactions, conformational entropy, and polar interactions in the stabilization of membrane proteins. Although the database of thermodynamic information is not yet large, a few generalities are beginning to emerge concerning the energetic differences between membrane and water-soluble proteins: the packing of apolar side chains in the interior of helical membrane proteins plays a smaller, but nevertheless significant, role in stabilizing their structure. Polar, hydrogen-bonded interactions occur less frequently, but, nevertheless, they often provide a strong driving force for folding helix,helix pairs in membrane proteins. These studies are laying the groundwork for the design of sequence motifs that dictate the association of membrane helices. [source] United and Divided: Christianity, Tradition and Identity in Two South Coast Papua New Guinea VillagesTHE AUSTRALIAN JOURNAL OF ANTHROPOLOGY, Issue 2 2003Michael Goddard The Motu and the Hula, two south coast Papua New Guinea societies, are linguistically related, have similar social organisation and were economically linked before European colonisation. They were both introduced to Christianity by the London Missionary Society in the late 19th century, and each appeared to incorporate the new religion into their social life and thought quickly and unproblematically. More than a century later, however, generalities about the similar adoption of Christianity by the Motu and the Hula are no longer possible. Nor are generalities about the engagement with Christianity within one or the other group, as individual Motu and Hula villages have unique histories. In this regard, while Christianity has now arguably become part of putative tradition among the Motu, some Hula are experiencing conflict between Christianity and their sense of tradition. In particular, while in the Motu village of Pari Christian virtues are appealed to as part of Pari's conception of itself as a ,traditional' Motu village, the situation in the Hula village of Irupara is more or less the contrary. Many people in Irupara are now lamenting ,tradition' as something lost, a forgotten essence destroyed or replaced by Christianity. Based on fieldwork in both villages, this paper discusses some differences in their engagement with Christianity and compares contemporary perceptions of religion, tradition and identity in both societies, informing a commentary on notions of tradition and anthropological representations of the Melanesian experience of Christianity. [source] The immediate-early oncoproteins Fra-1, c-Fos, and c-Jun have distinguishable surface behavior and interactions with phospholipidsBIOPOLYMERS, Issue 9 2009María Cecilia Gaggiotti Abstract This work explores the surface properties of the transcription factor Fra-1 and compares them with those of two other immediate early proteins, c-Fos and c-Jun, to establish generalities and differences in the surface behavior and interaction with phospholipids of this type of proteins. We present several experimental clues of the flexible nature of Fra-1, c-Fos, and c-Jun that support sequence-based predictions of their intrinsical disorder. The values of surface parameters for Fra-1 are similar in general to those of c-Fos and c-Jun. However, we find differences in the interactions of the three proteins with phospholipids. The closely related Fra-1 and c-Fos share affinity for anionic lipids but the former has more affinity for a condensed phase and senses a change in DPPC phase, while the latter has more affinity for an expanded phase. These features are in contrast with our previous finding that c-Jun is not selective for phospholipid polar head group or charge. We show here that at least some immediate early transcription factors can interact with membrane phospholipids in a distinguishable manner, and this shall provide a basis for their potential capacity to regulate membrane-mediated cellular processes. © 2009 Wiley Periodicals, Inc. Biopolymers 91: 710,718, 2009. This article was originally published online as an accepted preprint. The "Published Online" date corresponds to the preprint version. You can request a copy of the preprint by emailing the Biopolymers editorial office at biopolymers@wiley.com [source] Strategy and Opportunism in European Retail InternationalizationBRITISH JOURNAL OF MANAGEMENT, Issue 4 2001John Dawson Europe in recent years has witnessed an increase in the amount of cross-border operations by retailers. The retail sector has undergone substantial structural change characterized by the emergence of a group of rapidly-growing large retailers, a redefinition of the balance of internalized and externalized functions and a need to respond to the cultural variety present in Europe that becomes evident as retailers move out of their domestic markets. The over-arching requirement for these large retailers is to grow and gain scale economies. Internationalization of operations has become a requirement for these large firms. It is argued that the established academic conceptualizations of internationalization are unsatisfactory in not addressing this overriding requirement for growth. There is great variety in the international activity in retailing, with the absence of pattern being one of the few generalities. It is proposed that consideration of opportunism may be a better way to gain understanding of retailer activity than trying to fit activity into deterministic strategic models. The experiences of five West European retailers entering and building retail networks in Poland is provided as evidence for this view. Suggestions are made for future work exploring this issue of opportunism as a process in international retailing. [source] Furstyling on angle-split shell texturesCOMPUTER ANIMATION AND VIRTUAL WORLDS (PREV: JNL OF VISUALISATION & COMPUTER ANIMATION), Issue 2-3 2009Bin Sheng Abstract This paper presents a new method for modeling and rendering fur with a wide variety of furstyles. We simulate virtual fur using shell textures,a multiple layers of textured slices for its generality and efficiency. As shell textures usually suffer from the inherent visual gap errors due to the uniform discretization nature, we present the angle-split shell textures (ASST) approach, which classifies the shell textures into different types with different numbers of texture layers, by splitting the angle space of the viewing angles between fur orientation and view direction. Our system can render the fur with biological patterns, and utilizes vector field and scalar field on ASST to control the geometric variations of the furry shape. Users can intuitively shape the fur by applying the combing, blowing, and interpolating effects in real time. Our approach is intuitive to implement without using complex data structures, with real-time performance for dynamic fur appearances. Copyright © 2009 John Wiley & Sons, Ltd. [source] Provably Good 2D Shape Reconstruction from Unorganized Cross-SectionsCOMPUTER GRAPHICS FORUM, Issue 5 2008Pooran Memari Abstract This paper deals with the reconstruction of 2-dimensional geometric shapes from unorganized 1-dimensional cross-sections. We study the problem in its full generality following the approach of Boissonnat and Memari [BM07] for the analogous 3D problem. We propose a new variant of this method and provide sampling conditions to guarantee that the output of the algorithm has the same topology as the original object and is close to it (for the Hausdorff distance). [source] Geometric algebra and transition-selective implementations of the controlled-NOT gateCONCEPTS IN MAGNETIC RESONANCE, Issue 1 2004Timothy F. Havel Geometric algebra provides a complete set of simple rules for the manipulation of product operator expressions at a symbolic level, without any explicit use of matrices. This approach can be used not only to describe the state and evolution of a spin system, but also to derive the effective Hamiltonian and associated propagator in full generality. In this article, we illustrate the use of geometric algebra via a detailed analysis of transition-selective implementations of the controlled-NOT gate, which plays a key role in NMR-based quantum information processing. In the appendices, we show how one can also use geometric algebra to derive tight bounds on the magnitudes of the errors associated with these implementations of the controlled-NOT. © 2004 Wiley Periodicals, Inc. Concepts Magn Reson Part A 23A: 49,62, 2004 [source] A standards-based Grid resource brokering service supporting advance reservations, coallocation, and cross-Grid interoperabilityCONCURRENCY AND COMPUTATION: PRACTICE & EXPERIENCE, Issue 18 2009Erik Elmroth Abstract The problem of Grid-middleware interoperability is addressed by the design and analysis of a feature-rich, standards-based framework for all-to-all cross-middleware job submission. The architecture is designed with focus on generality and flexibility and builds on extensive use, internally and externally, of (proposed) Web and Grid services standards such as WSRF, JSDL, GLUE, and WS-Agreement. The external use provides the foundation for easy integration into specific middlewares, which is performed by the design of a small set of plugins for each middleware. Currently, plugins are provided for integration into Globus Toolkit 4 and NorduGrid/ARC. The internal use of standard formats facilitates customization of the job submission service by replacement of custom components for performing specific well-defined tasks. Most importantly, this enables the easy replacement of resource selection algorithms by algorithms that address the specific needs of a particular Grid environment and job submission scenario. By default, the service implements a decentralized brokering policy, striving to optimize the performance for the individual user by minimizing the response time for each job submitted. The algorithms in our implementation perform resource selection based on performance predictions, and provide support for advance reservations as well as coallocation of multiple resources for coordinated use. The performance of the system is analyzed with focus on overall service throughput (up to over 250 jobs per min) and individual job submission response time (down to under 1,s). Copyright © 2009 John Wiley & Sons, Ltd. [source] Estimating Diversity in Unsampled Habitats of a Biogeographical ProvinceCONSERVATION BIOLOGY, Issue 3 2003Michael L. Rosenzweig A number of methods have been developed to overcome sample-size limits within a single habitat. We evaluated six of these methods to see whether they could also compensate for incomplete habitat samples. We applied them to the butterfly species of the 110 ecoregions of Canada and the United States. Two of the methods use the frequency of species that occur in a few of the sampled ecoregions. These two methods did not work. The other four methods estimate the asymptote of the species-accumulation curve ( the graph of "number of species in a set of samples" versus "number of species occurrences in those samples" ). The asymptote of this curve is the actual number of species in the system. Three of these extrapolation estimators produced good estimates of total diversity even when limited to 10% of the ecoregions. Good estimates depend on sampling ecoregions that are hyperdispersed in space. Clustered sampling designs ruin the usefulness of the three successful methods. To ascertain their generality, our results must be duplicated at other scales and for other taxa and in other provinces. Resumen: La estimación del número de especies en una provincia biogeográfica puede ser problemático. Se ha desarrollado un número de métodos para superar los límites del tamaño de muestra dentro de un solo hábitat. Evaluamos seis de estos métodos para ver si podrían compensar por muestras incompletas de hábitat. Aplicamos estos métodos a especies de mariposas de las 110 ecoregiones de Canadá y los Estados Unidos. Dos de los métodos usan la frecuencia de las especies que ocurren en algunas de las ecoregiones muestreadas. Estos dos métodos no sirvieron. Los otros cuatro métodos estimaron la asíntota de la curva de acumulación de especies ( la gráfica de "el número de especies en un juego de muestras" contra el "número de ocurrencias de especies en éstas muestras" ). La asíntota de ésta curva es el número real de especies en el sistema. Tres de éstos estimadores de extrapolación produjeron buenas estimaciones de la diversidad total aún cuando se limitaron al 10% de las ecoregiones. Las buenas estimaciones dependen del muestreo de ecoregiones altamente dispersas en el espacio. Los diseños de muestreos en agrupamientos arruinan la utilidad de los tres métodos exitosos. Para asegurar su generalidad, nuestros resultados deben ser duplicados a otras escalas y para otros taxones en otras provincias. [source] SELF-CONTROL, CRIMINAL MOTIVATION AND DETERRENCE: AN INVESTIGATION USING RUSSIAN RESPONDENTSCRIMINOLOGY, Issue 2 2005CHARLES R. TITTLE With data from respondents in Nizhni Novgorod, Russia, we address the generality of self-control theory. We also assess two hypotheses. The first focuses on the attractiveness of criminal acts, that is, motivation toward crime. The second concerns the contention that the mediating link between self-control and criminal conduct is the failure of those with less self-control to anticipate the long-term costs of misbehavior. Although the magnitude of associations between self-control and indicators of criminal behavior is about the same in this study as it is in others, which suggests that the theory is not culturally bound, those associations are largely overshadowed by criminal attraction. Consistent with that, failure to anticipate costly long-term consequences does not appear to be the mediating link between self-control and criminal behavior: the evidence shows no tendency for sanction fear to be greater among those with greater self-control. In fact, sanction fear is modestly and significantly related to the crime measures independent of self-control, though sanction fear also appears to be influenced by criminal attraction. The results suggest that in the production of criminal behavior, motivation may be more important than controls inhibiting criminal impulses. [source] SOCIAL DISORGANIZATION OUTSIDE THE METROPOLIS: AN ANALYSIS OF RURAL YOUTH VIOLENCE,CRIMINOLOGY, Issue 1 2000D. WAYNE OSGOOD In order to extend the study of community social disorganization and crime beyond its exclusive focus on large urban centers, we present an analysis of structural correlates of arrest rates for juvenile violence in 264 nonmetropolitan counties of four states. Findings support the generality of social disorganization theory: Juvenile violence was associated with rates of residential instability, family disruption, and ethnic heterogeneity. Though rates of poverty were not related to juvenile violence, this is also in accord with social disorganization theory because, unlike urban settings, poverty was negatively related to residential instability. Rates of juvenile violence varied markedly with population size through a curvilinear relationship in which counties with the smallest juvenile populations had exceptionally low arrest rates. Analyses used negative binomial regression (a variation of Poisson regression) because the small number of arrests in many counties meant that arrest rates would be ill suited to least-squares regression. [source] Generality with specificity: the dynamic field theory generalizes across tasks and time scalesDEVELOPMENTAL SCIENCE, Issue 4 2008Vanessa R. Simmering A central goal in cognitive and developmental science is to develop models of behavior that can generalize across both tasks and development while maintaining a commitment to detailed behavioral prediction. This paper presents tests of one such model, the Dynamic Field Theory (DFT). The DFT was originally proposed to capture delay-dependent biases in spatial recall and developmental changes in spatial recall performance. More recently, the theory was generalized to adults' performance in a second spatial working memory task, position discrimination. Here we use the theory to predict a specific, complex developmental pattern in position discrimination. Data with 3- to 6-year-old children and adults confirm these predictions, demonstrating that the DFT achieves generality across tasks and time scales, as well as the specificity necessary to generate novel, falsifiable predictions. [source] Natural and accidental torsion in one-storey structures on elastic foundation under non-vertically incident SH-wavesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 7 2006Javier Avilés Abstract Factors , and , used in equivalent static analysis to account for natural and accidental torsion are evaluated with consideration of soil,structure interaction. The combined torsional effects of structural asymmetry and foundation rotation are examined with reference to a single monosymmetric structure placed on a rigid foundation that is embedded into an elastic half-space, under to the action of non-vertically incident SH waves. Dynamic and accidental eccentricities are developed such that when used together with the code-specified base shear, the resulting static displacement at the flexible edge of the building is identical to that computed from dynamic analysis. It is shown that these eccentricities do not have a unique definition because they depend on both the selection of the design base shear and the criterion used for separation of the torsional effects of foundation rotation from those of structural asymmetry. Selected numerical results are presented in terms of dimensionless parameters for their general application, using a set of appropriate earthquake motions for ensuring generality of conclusions. The practical significance of this information for code-designed buildings is elucidated. Copyright © 2006 John Wiley & Sons, Ltd. [source] Frequency domain modal analysis of earthquake input energy to highly damped passive control structuresEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2004Izuru Takewaki Abstract A new complex modal analysis-based method is developed in the frequency domain for efficient computation of the earthquake input energy to a highly damped linear elastic passive control structure. The input energy to the structure during an earthquake is an important measure of seismic demand. Because of generality and applicability to non-linear structures, the earthquake input energy has usually been computed in the time domain. It is shown here that the formulation of the earthquake input energy in the frequency domain is essential for deriving a bound on the earthquake input energy for a class of ground motions and for understanding the robustness of passively controlled structures to disturbances with various frequency contents. From the viewpoint of computational efficiency, a modal analysis-based method is developed. The importance of overdamped modes in the energy computation of specific non-proportionally damped models is demonstrated by comparing the energy transfer functions and the displacement transfer functions. Through numerical examinations for four recorded ground motions, it is shown that the modal analysis-based method in the frequency domain is very efficient in the computation of the earthquake input energy. Copyright © 2004 John Wiley & Sons, Ltd. [source] Comparative response analysis of conventional and innovative seismic protection strategiesEARTHQUAKE ENGINEERING AND STRUCTURAL DYNAMICS, Issue 5 2002S. Bruno Abstract The paper presents a numerical investigation aimed at evaluating the improvements achievable through devices for passive seismic protection of buildings based on the use of shape memory alloys (SMA) in place of conventional steel or rubber devices. To get some generality in the results, different resisting reinforced concrete plane frames were analysed, either protected or not. ,New' and ,existing' buildings were considered depending on whether seismic provisions are adopted in the building design or not. Base isolation and energy dissipation were equally addressed for both conventional and innovative SMA-based devices. Fragility analyses were performed using specific damage measures to account for comparisons among different damage types; the results were then used to estimate quantitatively the effectiveness of the various protection systems. More specifically, the assessment involved a direct comparison of the damage reduction provided by each protection system with respect to the severe degradation experienced by the corresponding non-protected frame. Structural damage, non-structural damage and damage to contents were used on purpose and included in a subsequent phase of cost analysis to evaluate the expected gains also in terms of economic benefits and life loss prevention. The results indicate that base isolation, when applicable, provides higher degrees of safety than energy dissipation does; moreover, the use of SMA-based devices generally brings about better performances, also in consideration of the reduced functional and maintenance requirements. Copyright © 2002 John Wiley & Sons, Ltd. [source] Integrating highly diverse invertebrates into broad-scale analyses of cross-taxon congruence across the PalaearcticECOGRAPHY, Issue 6 2009Andreas Schuldt Our knowledge on broad-scale patterns of biodiversity, as a basis for biogeographical models and conservation planning, largely rests upon studies on the spatial distribution of vertebrates and plants, neglecting large parts of the world's biodiversity. To reassess the generality of these patterns and better understand spatial diversity distributions of invertebrates, we analyzed patterns of species richness and endemism of a hyperdiverse insect taxon, carabid beetles (ca 11 000 Palaearctic species known), and its cross-taxon congruence with well-studied vertebrates (amphibians, reptiles) and plants across 107,units of the Palaearctic. Based on species accumulation curves, we accounted for completeness of the carabid data by separately examining the western (well-sampled) and eastern (partly less well-sampled) Palaearctic and China (deficient data). For the western Palaearctic, we highlight overall centers of invertebrate, vertebrate and plant diversity. Species richness and endemism of carabids were highly correlated with patterns of especially plant and amphibian diversity across large parts of the Palaearctic. For the well-sampled western Palaearctic, hotspots of diversity integrating invertebrates were located in Italy, Spain and Greece. Only analysis of Chinese provinces yielded low congruence between carabids and plants/vertebrates. However, Chinese carabid diversity is only insufficiently known and China features the highest numbers of annual new descriptions of carabids in the Palaearctic. Even based on the incomplete data, China harbors at least 25% of all Palaearctic carabid species. Our study shows that richness and endemism patterns of highly diverse insects can exhibit high congruence with general large scale patterns of diversity inferred from plants/vertebrates and that hotspots derived from the latter can also include a high diversity of invertebrates. In this regard, China qualifies as an outstanding multi-taxon hotspot of diversity, requiring intense biodiversity research and conservation effort. Our findings extend the limited knowledge on broad-scale invertebrate distributions and allow for a better understanding of diversity patterns across a larger range of the world's biodiversity than usually considered. [source] Density-dependent dispersal in birds and mammalsECOGRAPHY, Issue 3 2005Erik Matthysen Density-dependent dispersal can be caused by various mechanisms, from competition inducing individuals to emigrate (positive density-dependence) to social crowding effects impeding free movement (negative density-dependence). Various spatial population models have incorporated positively density-dependent dispersal algorithms, and recent theoretical models have explored the conditions for density-dependent dispersal (DD) to evolve. However, while the existence of DD is well documented in some taxa such as insects, there is no clear picture on its generality in vertebrates. Here I review the available empirical data on DD in birds and mammals, focusing mainly on variation in dispersal between years and on experimental density manipulations. Surprisingly few studies have explicitly focused on DD, and interpretation of the available data is often hampered by differences in approach, small sample sizes and/or statistical shortcomings. Positive DD was reported in 50 and 33% of the selected mammal and bird studies, respectively, while two studies on mammals (out of eight) reported negative DD. Among bird studies, DD was more often reported for emigration rates or long-distance recoveries than for average distances within finite study areas. Experimental studies manipulating densities (mainly on mammals) have consistently generated positive DD, typically showing reduced emigration in response to partial population removal. Studies that examined dispersal in relation to seasonal changes in density (small mammals only) have more often reported negative DD. Studies that compared dispersal between sites differing in density, also show a mixture of positive and negative DD. This suggests that dispersal changes in a more complex way with seasonal and spatial density variation than with annual densities, and/or that these results are confounded by other factors differing between seasons and sites, such as habitat quality. I conclude that both correlational and experimental studies support the existence of positive, rather than negative, density-dependent dispersal in birds and mammals. [source] A review of competition in north temperate dung beetle communitiesECOLOGICAL ENTOMOLOGY, Issue 1 2003John A. Finn Abstract. 1. Studies of north temperate dung beetle communities frequently invoke competition as an influential ecological process. In this review, the evidence for competition in north temperate dung beetle communities is evaluated and the role of competition as a factor affecting community structure is assessed. 2. Resource limitation and the evidence for interspecific competition are assessed by collating the available experimental and observational evidence for both the adult and larval stages of the dung beetle life cycle. The role of competition as a structuring force in dung beetle communities is discussed under the following headings: niche dynamics, migration to and from individual pats, the aggregation model of co-existence, and metapopulations. 3. Some of the main conclusions are that competition for space is much more likely to occur than competition for food; the effects of competition on community structure are poorly understood; several of the influential studies of competition in north temperate dung beetle communities need to be evaluated carefully. The differences in ecology between tropical and temperate dung beetle communities are clarified. 4. As priorities for future research, resource utilisation and competition should be researched experimentally: density-dependent relationships should be investigated, particularly for the larval stages, as should competitive interactions with other dung fauna. If such experimental approaches establish convincingly the occurrence of competition, then the extent of competition in the field and under real world conditions needs to be established. A functional group classification of dung beetles and other dung fauna is described, which may improve the generality of interpretation from individual, site-specific results. [source] Against Bergmann's rule: fly sperm size increases with temperatureECOLOGY LETTERS, Issue 1 2002Wolf U. Blanckenhorn A long-standing school textbook biological rule, Bergmann's rule, asserts that animals (and their constituent parts) grow bigger when it is colder. This seems to hold for many warm-blooded animals, as well as for egg, cell and body size of most cold-blooded animals. A unifying mechanism producing this pattern has not been found. We here provide the first experimental evidence that the size of an important type of cell, namely sperm, increases (rather than decreases) with temperature in a cold-blooded animal, the yellow dung fly. By pointing to an exception, our work either questions the generality of one prominent category of explanation of Bergmann's rule, that of a physiological constraint, or alternatively suggests that sperm differ fundamentally in their physiology from other cells. [source] Complexity can enhance stability in competitive systemsECOLOGY LETTERS, Issue 5 2001Ian D. Rozdilsky Empirical observations often indicate that complexity enhances stability, while most theoretical studies, such as May's (1972) classic paper, point to the opposite. Despite the wide generality of these latter theoretical analyses, our examination of the well-known competitive Lotka,Volterra system reveals that increasing complexity (measured in terms of connectance) can enhance species coexistence and persistence in model communities (measured in terms of their feasibility and stability). The high feasibility and stability found for tightly interconnected competitive subsystems might provide an explanation for the clumped structure in food webs. [source] A Web page that provides map-based interfaces for VRML/X3D contentELECTRONICS & COMMUNICATIONS IN JAPAN, Issue 2 2009Yoshihiro Miyake Abstract The electronic map is very useful for navigation in the VRML/X3D virtual environments. So far various map-based interfaces have been developed. But they are lacking for generality because they have been separately developed for individual VRML/X3D contents, and users must use different interfaces for different contents. Therefore, we have developed a Web page that provides a common map-based interface for VRML/X3D contents on the Web. Users access VRML/X3D contents via the Web page. The Web page automatically generates a simplified map by analyzing the scene graph of downloaded contents, and embeds the mechanism to link the virtual world and the map. An avatar is automatically created and added to the map, and both a user and its avatar are bidirectionally linked together. In the simplified map, obstructive objects are removed and the other objects are replaced by base boxes. This paper proposes the architecture of the Web page and the method to generate simplified maps. Finally, an experimental system is developed in order to show the improvement of frame rates by simplifying the map. © 2009 Wiley Periodicals, Inc. Electron Comm Jpn, 92(2): 28,37, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/ecj.10017 [source] Critical period of sensitivity for effects of cadmium on frog growth and development,ENVIRONMENTAL TOXICOLOGY & CHEMISTRY, Issue 6 2009Jackson A. Gross Abstract Cadmium is a ubiquitous pollutant in aquatic environments that can alter organismal physiology and ecology. Previous experiments found that ecological Cd exposures increased the growth and development of two North American anurans. However, the generality of these effects among species, the time period over which they occur, and the mechanisms responsible remain conjectural. The goal of the present study was to determine the critical period of sensitivity of Rana pipiens exposed to ecologically relevant levels of Cd. We exposed tadpoles to Cd (0 [control], 1.0, and 10.0 ,g/L) from Gosner stage (GS) 25 to metamorphic climax. We assessed effects of Cd on amphibian length, survival, and development during premetamorphosis (GS 25,30) and prometamorphosis (GS 31,42). After 14 d of exposure, we staged tadpoles and recorded snout-vent length. Tadpoles were then pooled according to treatment and stage (GS , 29 or GS , 30) and allowed to undergo metamorphic development. Tadpoles exposed to 10 ,g/L were significantly larger and more advanced in development by 14 d. Survival to forelimb emergence exceeded 90% in all treatments, and time to metamorphic climax was not different from that in controls. Body burdens of Cd were positively correlated with increasing treatment. Early amphibian development (premetamorphosis) was shown to be the critical period of sensitivity for growth and development. Whereas the freshwater criterion for Cd appears to be protective for survival, a lack of knowledge remains about the sublethal effects of chronic exposures of metal pollutants, especially as they relate to tissue concentrations at various stages of amphibian life history. [source] | ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||