990 resultados para Evolutionary adaptation


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1. A neuropeptide exhibiting pancreatic polypeptide-immunoreactivity (PP-IR) has been isolated and characterised from the parasitic platyhelminth, Diclidophora merlangi.

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In this paper we study the influence of interventions on self-interactions in a spatial Prisoner's Dilemma on a two-dimensional grid with periodic boundary conditions and synchronous updating of the dynamics. We investigate two different types of self-interaction modifications. The first type (FSIP) is deterministic, effecting each self-interaction of a player by a constant factor, whereas the second type (PSIP) performs a probabilistic interventions. Both types of interventions lead to a reduction of the payoff of the players and, hence, represent inhibiting effects. We find that a constant but moderate reduction of self-interactions has a very beneficial effect on the evolution of cooperators in the population, whereas probabilistic interventions on self-interactions are in general counter productive for the coexistence of the two different strategies. (C) 2011 Elsevier Inc. All rights reserved.

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Human motor behaviour is continually modified on the basis of errors between desired and actual movement outcomes. It is emerging that the role played by the primary motor cortex (M1) in this process is contingent upon a variety of factors, including the nature of the task being performed, and the stage of learning. Here we used repetitive TMS to test the hypothesis that M1 is intimately involved in the initial phase of sensorimotor adaptation. Inhibitory theta burst stimulation was applied to M1 prior to a task requiring modification of torques generated about the elbow/forearm complex in response to rotations of a visual feedback display. Participants were first exposed to a 30° clockwise (CW) rotation (Block A), then a 60° counterclockwise rotation (Block B), followed immediately by a second block of 30° CW rotation (A2). In the STIM condition, participants received 20s of continuous theta burst stimulation (cTBS) prior to the initial A Block. In the conventional (CON) condition, no stimulation was applied. The overt characteristics of performance in the two conditions were essentially equivalent with respect to the errors exhibited upon exposure to a new variant of the task. There were however, profound differences between the conditions in the latency of response preparation, and the excitability of corticospinal projections from M1, which accompanied phases of de-adaptation and re-adaptation (during Blocks B and A2). Upon subsequent exposure to the A rotation 24h later, the rate of re-adaptation was lower in the stimulation condition than that present in the conventional condition. These results support the assertion that primary motor cortex assumes a key role in a network that mediates adaptation to visuomotor perturbation, and emphasise that it is engaged functionally during the early phase of learning.

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The use of dataflow digital signal processing system modelling
and synthesis techniques has been a fruitful research theme for many years and has yielded many powerful rapid system synthesis and optimisation capabilities. However, recent years have seen the spectrum of languages and techniques splinter in an application specific manner, resulting in an ad-hoc design process which is increasingly dependent on the particular application under development. This poses a major problem for automated toolflows attempting to provide rapid system synthesis for a wide ranges of applications. By analysing a number of dataflow FPGA implementation case studies, this paper shows that despit ethis common traits may be found in current techniques, which fall largely into three classes. Further, it exposes limitations pertaining to their ability to adapt algorith models to implementations for different operating environments and target platforms.

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The expression of two or more discrete phenotypes amongst individuals within a species (morphs) provides multiple modes upon which selection can act semi-independently, and thus may be an important stage in speciation. In the present study, we compared two sympatric morph systems aiming to address hypotheses related to their evolutionary origin. Arctic charr in sympatry in Loch Tay, Scotland, exhibit one of two discrete, alternative body size phenotypes at maturity (large or small body size). Arctic charr in Loch Awe segregate into two temporally segregated spawning groups (breeding in either spring or autumn). Mitochondrial DNA restriction fragment length polymorphism analysis showed that the morph pairs in both lakes comprise separate gene pools, although segregation of the Loch Awe morphs is more subtle than that of Loch Tay. We conclude that the Loch Awe morphs diverged in situ (within the lake), whereas Loch Tay morphs most likely arose through multiple invasions by different ancestral groups that segregated before post-glacial invasion (i.e. in allopatry). Both morph pairs showed clear trophic segregation between planktonic and benthic resources (measured by stable isotope analysis) but this was significantly less distinct in Loch Tay than in Loch Awe. By contrast, both inter-morph morphological and life-history differences were more subtle in Loch Awe than in Loch Tay. The strong ecological but relatively weak morphological and life-history divergence of the in situ derived morphs compared to morphs with allopatric origins indicates a strong link between early ecological and subsequent genetic divergence of sympatric origin emerging species pairs. The emergence of parallel specialisms despite distinct genetic origins of these morph pairs suggests that the effect of available foraging opportunities may be at least as important as genetic origin in structuring sympatric divergence in post-glacial fishes with high levels of phenotypic plasticity. (c) 2012 The Linnean Society of London, Biological Journal of the Linnean Society, 2012, , .

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This paper describes the result of a project to develop climate adaptation design strategies funded by the UK’s Technology Strategy Board. The aim of the project was to look at the effects of climate change in the distant future (2080) on a vulnerable group such as older people with special needs and see how architectural design strategies and technologies may be used today to help mitigate problems ahead caused by climate change.
Older people are the most vulnerable sector of society and are particularly at risk in extreme weather, either excess cold in winter or continual high temperatures in summer. In the UK it is predicted that average temperatures may rise by as much as 8 degrees in Summer by 2080 and there will be a 20% greater chance of extreme weather events. This will place extreme stress on the building stock which is designed for today’s mild maritime climate.
The project took a current proposal for an extra-care home for the elderly designed to 2010 regulations and developed a road map to 2080 using climate models developed by the UK Meteorological Office. This allowed the current design to be assessed using future climatic data, proposals for improvement of the scheme to be made within existing constraints and also a new scheme to be developed from first principals using this data, and projections of new technologies that will be available. By comparing these schemes, the approach allowed a reassessment of the initial scheme, and allowed a new design to be developed that offered a more flexible solution incorporating future retrofit which allows new renewable technologies for heating, cooling and water storage to be added at a later date.

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Diversity is a defining characteristic of modern society, yet there remains considerable debate over the benefits that it brings. The authors argue that positive psychological and behavioral outcomes will be observed only when social and cultural diversity is experienced in a way that challenges stereotypical expectations and that when this precondition is met, the experience has cognitive consequences that resonate across multiple domains. A model, rooted in social categorization theory and research, outlines the preconditions and processes through which people cognitively adapt to the experience of social and cultural diversity and the resulting cross-domain benefits that this brings. Evidence is drawn from a range of literatures to support this model, including work on biculturalism, minority influence, cognitive development, stereotype threat, work group productivity, creativity, and political ideology. The authors bring together a range of differing diversity experiences and explicitly draw parallels between programs of research that have focused on both perceiving others who are multicultural and being multicultural oneself. The findings from this integrative review suggest that experiencing diversity that challenges expectations may not only encourage greater tolerance but also have benefits beyond intergroup relations to varied aspects of psychological functioning.

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The common prior assumption justifies private beliefs as posterior probabilities when updating a common prior based on individual information. We dispose of the common prior assumption for a homogeneous oligopoly market with uncertain costs and firms entertaining arbitrary priors about other firms' cost-type. We show that true prior beliefs can not be evolutionarily stable when truly expected profit measures (reproductive) success.

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Structured Abstract:
Purpose: Very few studies investigate environmentally responsible behaviour (ERB). This paper presents a new 'Awareness Behaviour Intervention Action' (ABIA) Decision Support Framework to sustain ERB.

Design/methodology/approach: Previous ERB programmes have failed to deliver lasting results; they have not appropriately understood and provided systems to address ERB (Costanzo et al., 1986). These programmes were based on assumptions (Moloney et al., 2010), which this paper addresses. The ABIA Framework has been developed through a case study of social housing tenants waiting for low or zero carbon homes.

Findings: The ABIA Framework enables a better understanding of current attitudes to environmental issues and provides support for ERB alongside technological interventions employed to promote and sustain carbon reduction.

Research limitations/implications: The ABIA Framework should be tested on individuals and communities in a variety of socio-economic, political and cultural contexts. This will help unpack how it can impact on the behaviours of individuals and communities including stakeholders.

Practical implications: This type of research and the ABIA Framework developed from it are crucial if the UK pledge to become the first country in the World where all new homes from 2016 are to be zero carbon.

Social implications: The Framework encourages both individual and community discussion and solving of sustainability issues.

Originality/value: There are few, if any, studies that have developed a framework which can be used to support behavioural change for adaptation to sustainable living in low or zero carbon homes.

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The optimization of cutouts in composite plates was investigated by implementing a procedure known as Evolutionary Structural Optimization. Perforations were introduced into a finite element mesh of the plate from which one or more cutouts of a predetermined size were evolved. In the examples presented, plates were rejected from around each evolving cutout based on a predefined rejection criterion. The Limiting ply within each plate element around the cutout was determined based on the Tsai-Hill failure criterion. Finite element plates with values below the product of the average Tsai-Hill number and a rejection criterion were subsequently removed. This process was iterated until a steady state was reached and the rejection criterion was then incremented by an evolutionary rate and the above steps repeated until the desired cutout area was achieved. Various plates with differing lay-up and loading parameters were investigated to demonstrate the generality and robustness of this optimization procedure.