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Selected AbstractsTHE COEVOLUTIONARY DYNAMICS OF ANTAGONISTIC INTERACTIONS MEDIATED BY QUANTITATIVE TRAITS WITH EVOLVING VARIANCESEVOLUTION, Issue 10 2005Scott L. Nuismer Abstract Quantitative traits frequently mediate coevolutionary interactions between predator and prey or parasite and host. Previous efforts to understand and predict the coevolutionary dynamics of these interactions have generally assumed that standing genetic variation is fixed or absent altogether. We develop a genetically explicit model of coevolution that bridges the gap between these approaches by allowing genetic variation itself to evolve. Analysis of this model shows that the evolution of genetic variance has improtant consequences for the dyanmics and outcome of coevolution. Of particular importance is our demonstration that coevolutionary cycles can emerge in the absence of stabilizing selection, and outcome not possible in previous models of coevolution mediated by quantitative traits. whether coevolutionary cycles evolve depends upon the strength of selection, the number of loci, and the rate of mutation in each of the interacting species. Our results also generate novel predictions for the expected sign and magnitude of linkage disequilibria in each species. [source] Complete high-density lipoproteins in nanoparticle coronaFEBS JOURNAL, Issue 12 2009Erik Hellstrand In a biological environment, nanoparticles immediately become covered by an evolving corona of biomolecules, which gives a biological identity to the nanoparticle and determines its biological impact and fate. Previous efforts at describing the corona have concerned only its protein content. Here, for the first time, we show, using size exclusion chromatography, NMR, and pull-down experiments, that copolymer nanoparticles bind cholesterol, triglycerides and phospholipids from human plasma, and that the binding reaches saturation. The lipid and protein binding patterns correspond closely with the composition of high-density lipoprotein (HDL). By using fractionated lipoproteins, we show that HDL binds to copolymer nanoparticles with much higher specificity than other lipoproteins, probably mediated by apolipoprotein A-I. Together with the previously identified protein binding patterns in the corona, our results imply that copolymer nanoparticles bind complete HDL complexes, and may be recognized by living systems as HDL complexes, opening up these transport pathways to nanoparticles. Apolipoproteins have been identified as binding to many other nanoparticles, suggesting that lipid and lipoprotein binding is a general feature of nanoparticles under physiological conditions. [source] Phylogeography of ninespine sticklebacks (Pungitius pungitius) in North America: glacial refugia and the origins of adaptive traitsMOLECULAR ECOLOGY, Issue 18 2010JACLYN T. ALDENHOVEN Abstract The current geographical distribution of the ninespine stickleback (Pungitius pungitius) was shaped in large part by the glaciation events of the Pleistocene epoch (2.6 Mya,10 Kya). Previous efforts to elucidate the phylogeographical history of the ninespine stickleback in North America have focused on a limited set of morphological traits, some of which are likely subject to widespread convergent evolution, thereby potentially obscuring relationships among populations. In this study, we used genetic information from both mitochondrial DNA (mtDNA) sequences and nuclear microsatellite markers to determine the phylogenetic relationships among ninespine stickleback populations. We found that ninespine sticklebacks in North America probably dispersed from at least three glacial refugia,the Mississippi, Bering, and Atlantic refugia,not two as previously thought. However, by applying a molecular clock to our mtDNA data, we found that these three groups diverged long before the most recent glacial period. Our new phylogeny serves as a critical framework for examining the evolution of derived traits in this species, including adaptive phenotypes that evolved multiple times in different lineages. In particular, we inferred that loss of the pelvic (hind fin) skeleton probably evolved independently in populations descended from each of the three putative North American refugia. [source] Commercial Insurance vs Community-based Health Plans: Time for a Policy Option With Clinical Emphasis to Address the Cost SpiralTHE JOURNAL OF RURAL HEALTH, Issue 2 2005Bruce Amundson MD ABSTRACT: The nation continues its ceaseless struggle with the spiraling cost of health care. Previous efforts (regulation, competition, voluntary action) have included almost every strategy except clinical. Insurers have largely failed in their cost-containment efforts. There is a strong emerging body of literature that demonstrates the relationship between various clinical strategies and reductions in utilization and costs. This article describes the organization of health services, including integration of delivery and financing systems, at the community level as a model that effectively addresses the critical structural flaws that have frustrated control of costs. Community-based health plans (CHPs) have been developed and have demonstrated viability. The key elements of CHPs are a legal organizational structure, a full provider network, advanced care-management systems, and the ability to assume financial risk. Common misconceptions regarding obstacles to CHP development are the complexity of the undertaking, difficulty assuming the insurance function, and insured pools that are too small to be viable. The characteristics of successful CHPs and 2 case studies are described, including the types of advanced care-management systems that have resulted in strong financial performance. The demonstrated ability of CHPs to establish financial viability with small numbers of enrollees challenges the common assumption that there is a fixed relationship between health plan enrollment size and financial performance. Organizing the health system at the community/regional level provides an attractive alternative model in the health-reformdebate. There is an opportunity for clinical systems and state and federal leaders to support the development of community-based integrated delivery and financing system models that, among other advantages, have significant potential to modulate the pernicious cost spiral. [source] A Typology of Consumers' Emotional Response Styles during Service Recovery Encounters,BRITISH JOURNAL OF MANAGEMENT, Issue 3 2009Klaus Schoefer Previous efforts investigating consumers' response styles during service failure and recovery encounters have focused on behavioural elements and, by and large, neglected the important issue of emotions elicited in this context. The present study uses experienced emotions during service recovery encounters as a way of classifying complainants and links the resultant typology to the relationship quality indicators of satisfaction, trust and commitment. By doing so, it serves as an empirically grounded basis for subsequently deriving strategies and tactics for successful recovery from service failures. The results reveal four distinct emotional response styles which are associated with perceptions of relationship quality following service recovery encounters. Managerial implications of the findings are discussed and future research directions identified. [source] The European Research Area: On the Way Towards a European Scientific Community?EUROPEAN LAW JOURNAL, Issue 5 2006Álvaro De Elera The aim was to create an ,internal market of research', in contrast with previous efforts in research policy that amounted to continued fragmentation. Lack of support from both Member States and the Council, together with the almost exclusive use of the Open Method of Coordination for the design of the Area, meant that the initially high ambitions were not met. The social repercussions of the project were also watered down as a consequence. [source] Bacterivorous grazers facilitate organic matter decomposition: a stoichiometric modeling approachFEMS MICROBIOLOGY ECOLOGY, Issue 2 2009Hao Wang Abstract There is widespread empirical evidence that protist grazing on bacteria reduces bacterial abundances but increases bacteria-mediated decomposition of organic matter. This paradox has been noted repeatedly in the microbiology literature but lacks a generally accepted mechanistic explanation. To explain this paradox quantitatively, we develop a bacteria-grazer model of organic matter decomposition that incorporates protozoa-driven nutrient recycling and stoichiometry. Unlike previous efforts, the current model includes explicit limitation, via Liebig's law of minimum, by two possible factors, nutrient and carbon densities, as well as their relative ratios in bacteria and grazers. Our model shows two principal results: (1) when the environment is carbon limiting, organic matter can always be decomposed completely, regardless of the presence/absence of grazers; (2) when the environment is nutrient (such as nitrogen) limiting, it is possible for organic matter to be completely decomposed in the presence, but not absence, of grazers. Grazers facilitate decomposition by releasing nutrients back into the environment, which would otherwise be limiting, while preying upon bacteria. Model analysis reveals that facilitation of organic matter decomposition by grazers is positively related to the stoichiometric difference between bacteria and grazers. In addition, we predict the existence of an optimal density range of introduced grazers, which maximally facilitate the decomposition of organic matter in a fixed time period. This optimal range reflects a trade-off between grazer-induced nutrient recycling and grazer-induced mortality of bacteria. [source] Effects of density and ontogeny on size and growth ranks of three competing tree speciesJOURNAL OF ECOLOGY, Issue 2 2009Suzanne B. Boyden Summary 1Rank reversals in species performance are theoretically important for structuring communities, maintaining diversity and determining the course of forest succession. Species growth ranks can change with ontogeny or in different microenvironments, but interactions between ontogeny and the environment are not well-understood because of the lack of long-term forest competition studies. While early differences in growth among species may reflect intrinsic differences in shade-tolerance and physiology, ontogenetic trends in growth and variation in neighbourhood density and composition may change or even reverse early patterns of growth rankings. 2We experimentally studied spatial and temporal patterns of species interactions and growth for three northern tree species: Larix laricina, Picea mariana and Pinus strobus. We compared species size and growth rankings over an 11-year period, for different species mixtures planted at four density levels in north-eastern Minnesota, USA. 3The benefits of different growth strategies changed with ontogeny and density leading to reversals in the size rank of competing species over time and space. High-density stands promoted dominance and resource pre-emption by L. laricina, whereas lower-density stands favoured gradual accumulation of biomass and eventual dominance by P. strobus. In the absence of strong neighbour competition, ontogenetic trends in growth had greater influence on growth patterns. 4Species interactions affected the productivity of mixed stands vs. monocultures. Species generally grew more in monoculture than when planted with P. strobus at low density, or with L. laricina at high density. Only L. laricina and P. mariana showed potential for greater overall productivity, or over-yielding, when planted together than alone, probably because of improved resource uptake by the highly stratified canopy. 5Synthesis. Density predictably determined whether size-asymmetric growth or ontogenetic growth trends would drive early establishment and growth patterns. Variation in vertical and horizontal structure that results from early competitive dynamics can influence the successional trajectory or character of the mature forest. This study extends previous efforts to identify the causes of rank reversals in communities and understand the importance of temporal changes beyond the early years of seedling establishment. [source] Microstructural Corpus Callosum Anomalies in Children With Prenatal Alcohol Exposure: An Extension of Previous Diffusion Tensor Imaging FindingsALCOHOLISM, Issue 10 2009Jeffrey R. Wozniak Background:, Several studies have now shown corpus callosum abnormalities using diffusion tensor imaging (DTI) in children with fetal alcohol spectrum disorders (FASD) in comparison with nonexposed controls. The data suggest that posterior regions of the callosum may be disproportionately affected. The current study builds on previous efforts, including our own work, and moves beyond midline corpus callosum to probe major inter-hemispheric white matter pathways with an improved DTI tractographic method. This study also expands on our prior work by evaluating a larger sample and by incorporating children with a broader range of clinical effects including full-criteria fetal alcohol syndrome (FAS). Methods:, Participants included 33 children with FASD (8 FAS, 23 partial FAS, 2 static encephalopathy) and 19 nonexposed controls between the ages of 10 and 17 years. Participants underwent DTI scans and intelligence testing. Groups (FASD vs. controls) were compared on fractional anisotropy (FA) and mean diffusivity (MD) in 6 white matter tracts projected through the corpus callosum. Exploratory analyses were also conducted examining the relationships between DTI measures in the corpus callosum and measures of intellectual functioning and facial dysmorphology. Results:, In comparison with the control group, the FASD group had significantly lower FA in 3 posterior tracts of the corpus callosum: the posterior mid-body, the isthmus, and the splenium. A trend-level finding also suggested lower FA in the genu. Measures of white matter integrity and cognition were correlated and suggest some regional specificity, in that only posterior regions of the corpus callosum were associated with visual-perceptual skills. Correlations between measures of facial dysmorphology and posterior regions of the corpus callosum were nonsignificant. Conclusions:, Consistent with previous DTI studies, these results suggest that microstructural posterior corpus callosum abnormalities are present in children with prenatal alcohol exposure and cognitive impairment. These abnormalities are clinically relevant because they are associated with cognitive deficits and appear to provide evidence of abnormalities associated with prenatal alcohol exposure independent of dysmorphic features. As such, they may yield important diagnostic and prognostic information not provided by the traditional facial characteristics. [source] A conceptual model of perceived customer value in e-commerce: A preliminary investigationPSYCHOLOGY & MARKETING, Issue 4 2003Zhan Chen This article presents an exploratory study of a conceptual model of perceived customer value in a business-to-consumer e-commerce setting. Key precursors of perceived customer value included in the model are valence of on-line shopping experience, perceived product quality, perceived risk, and product price. Relationships among these variables (as well as mediating variables) and their relationship to on-line shoppers' value perceptions are explored. The theoretical framework proposed in this work expands on previous efforts on perceived customer value by including new variables relevant to an e-commerce setting and by integrating several key variables into one model. The preliminary findings lead to several implications. © 2003 Wiley Periodicals, Inc. [source] Primary and secondary prevention of behavior difficulties: Developing a data-informed problem-solving model to guide decision making at a school-wide levelPSYCHOLOGY IN THE SCHOOLS, Issue 1 2007Ruth A. Ervin This article focuses on the development and implementation of primary and secondary behavior supports at a schoolwide level. The approach described is consistent with previous efforts to address behavior at a systems level (e.g., G. Sugai, R.H. Horner, & F.M. Gresham, 2002). In this article, we illustrate this process through a school-based example. This example is drawn from a larger project in which area regional school-district consultants and university researchers partnered with four elementary schools in an effort to enhance each school's capacity to implement evidence-based practice and decisions at primary (i.e., universal or school-wide), secondary (i.e., targeted efforts for selected groups of students and/or settings), and tertiary (i.e., individual-student) levels to promote behavioral competence. The project incorporated promising strategies and tools designed to promote and sustain the use of evidence-based practices and data-driven problem solving. Continuous progress monitoring of systemic variables and student behavioral outcomes (e.g., office-referral data) helped to guide systemic reform efforts. Reductions were noted in the number of student discipline problems, and improvements were noted in critical features of school-wide effective behavior support at a systems level. Results are discussed with an emphasis on implications for practice, lessons learned from this project, and directions for additional research. © 2007 Wiley Periodicals, Inc. Psychol Schs 44: 7,18, 2007. [source] | ||||||||||||||||