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Sample records for adaptation evolution strategy

  1. APPLICATION OF RESTART COVARIANCE MATRIX ADAPTATION EVOLUTION STRATEGY (RCMA-ES TO GENERATION EXPANSION PLANNING PROBLEM

    Directory of Open Access Journals (Sweden)

    K. Karthikeyan

    2012-10-01

    Full Text Available This paper describes the application of an evolutionary algorithm, Restart Covariance Matrix Adaptation Evolution Strategy (RCMA-ES to the Generation Expansion Planning (GEP problem. RCMA-ES is a class of continuous Evolutionary Algorithm (EA derived from the concept of self-adaptation in evolution strategies, which adapts the covariance matrix of a multivariate normal search distribution. The original GEP problem is modified by incorporating Virtual Mapping Procedure (VMP. The GEP problem of a synthetic test systems for 6-year, 14-year and 24-year planning horizons having five types of candidate units is considered. Two different constraint-handling methods are incorporated and impact of each method has been compared. In addition, comparison and validation has also made with dynamic programming method.

  2. Laboratory Evolution to Alternating Substrate Environments Yields Distinct Phenotypic and Genetic Adaptive Strategies

    DEFF Research Database (Denmark)

    Sandberg, Troy E.; Lloyd, Colton J.; Palsson, Bernhard O.

    2017-01-01

    conditions and different adaptation strategies depending on the substrates being switched between; in some environments, a persistent "generalist" strain developed, while in another, two "specialist" subpopulations arose that alternated dominance. Diauxic lag phenotype varied across the generalists...... maintain simple, static culturing environments so as to reduce selection pressure complexity. In this study, we investigated the adaptive strategies underlying evolution to fluctuating environments by evolving Escherichia coli to conditions of frequently switching growth substrate. Characterization...... of evolved strains via a number of different data types revealed the various genetic and phenotypic changes implemented in pursuit of growth optimality and how these differed across the different growth substrates and switching protocols. This work not only helps to establish general principles of adaptation...

  3. Contemporary evolution strategies

    CERN Document Server

    Bäck, Thomas; Krause, Peter

    2013-01-01

    Evolution strategies have more than 50 years of history in the field of evolutionary computation. Since the early 1990s, many algorithmic variations of evolution strategies have been developed, characterized by the fact that they use the so-called derandomization concept for strategy parameter adaptation. Most importantly, the covariance matrix adaptation strategy (CMA-ES) and its successors are the key representatives of this group of contemporary evolution strategies. This book provides an overview of the key algorithm developments between 1990 and 2012, including brief descriptions of the a

  4. Convergent adaptive evolution in marginal environments: unloading transposable elements as a common strategy among mangrove genomes.

    Science.gov (United States)

    Lyu, Haomin; He, Ziwen; Wu, Chung-I; Shi, Suhua

    2018-01-01

    Several clades of mangrove trees independently invade the interface between land and sea at the margin of woody plant distribution. As phenotypic convergence among mangroves is common, the possibility of convergent adaptation in their genomes is quite intriguing. To study this molecular convergence, we sequenced multiple mangrove genomes. In this study, we focused on the evolution of transposable elements (TEs) in relation to the genome size evolution. TEs, generally considered genomic parasites, are the most common components of woody plant genomes. Analyzing the long terminal repeat-retrotransposon (LTR-RT) type of TE, we estimated their death rates by counting solo-LTRs and truncated elements. We found that all lineages of mangroves massively and convergently reduce TE loads in comparison to their nonmangrove relatives; as a consequence, genome size reduction happens independently in all six mangrove lineages; TE load reduction in mangroves can be attributed to the paucity of young elements; the rarity of young LTR-RTs is a consequence of fewer births rather than access death. In conclusion, mangrove genomes employ a convergent strategy of TE load reduction by suppressing element origination in their independent adaptation to a new environment. © 2017 The Authors. New Phytologist © 2017 New Phytologist Trust.

  5. Adaptability and evolution.

    Science.gov (United States)

    Bateson, Patrick

    2017-10-06

    The capacity of organisms to respond in their own lifetimes to new challenges in their environments probably appeared early in biological evolution. At present few studies have shown how such adaptability could influence the inherited characteristics of an organism's descendants. In part, this has been because organisms have been treated as passive in evolution. Nevertheless, their effects on biological evolution are likely to have been important and, when they occurred, accelerated the pace of evolution. Ways in which this might have happened have been suggested many times since the 1870s. I review these proposals and discuss their relevance to modern thought.

  6. Adaptive co-evolution of strategies and network leading to optimal cooperation level in spatial prisoner's dilemma game

    International Nuclear Information System (INIS)

    Han-Shuang, Chen; Zhong-Huai, Hou; Hou-Wen, Xin; Ji-Qian, Zhang

    2010-01-01

    We study evolutionary prisoner's dilemma game on adaptive networks where a population of players co-evolves with their interaction networks. During the co-evolution process, interacted players with opposite strategies either rewire the link between them with probability p or update their strategies with probability 1 – p depending on their payoffs. Numerical simulation shows that the final network is either split into some disconnected communities whose players share the same strategy within each community or forms a single connected network in which all nodes are in the same strategy. Interestingly, the density of cooperators in the final state can be maximised in an intermediate range of p via the competition between time scale of the network dynamics and that of the node dynamics. Finally, the mean-field analysis helps to understand the results of numerical simulation. Our results may provide some insight into understanding the emergence of cooperation in the real situation where the individuals' behaviour and their relationship adaptively co-evolve. (general)

  7. Evolution of ITER tritium confinement strategy and adaptation to Cadrache site conditions and French regulatory requirements

    International Nuclear Information System (INIS)

    Murdoch, D.

    2007-01-01

    The ITER Nuclear Buildings include the Tokamak, Tritium and Diagnostic Buildings (Tokamak Complex) and the Hot Cell and Low Level Radioactive Waste Buildings. The Tritium Confinement Strategy of the Nuclear Buildings comprises key features of the Atmosphere and Vent Detritiation Systems (ADS/VDS) and the Heating, Ventilation and Air Conditioning (HVAC) Systems. The designs developed during the ITER EDA (Engineering Design Activities) for these systems need to be adapted to the specific conditions of the Cadarache site and modified to conform with the regulatory requirements applicable to Installations Nucleaires de Base (INB) - Basic Nuclear Installations - in France. The highest priority for such adaptation has been identified as the Tritium Confinement of the Tokamak Complex and the progress in development of a robust, coherent design concept compliant with French practice is described in the paper. The Tokamak Complex HVAC concept for generic conditions was developed for operational cost minimisation under more extreme climatic conditions (primarily temperature) than those valid for Cadarache, and incorporated recirculation of a large fraction of the air flow through the HVAC systems to achieve this objective. Due to the impracticality of precluding the spread of contamination from areas of higher activity to less contaminated areas, this concept has been abandoned in favour of a once-through configuration, which requires a complete redesign, with revised air change rates, module sizes, layout, redundancy provisions and other features. The ADS/VDS concept developed for the generic design of the ITER Tokamak Complex is undergoing a radical revision in which the system architecture, module sizing and basic process are being optimised for the Cadarache conditions. Investigation is being launched into the implementation of a wet stripper concept to replace the molecular sieve (MS) beds incorporated in the generic design, where concerns have been raised over low

  8. Behavioural strategy: Adaptability context

    Directory of Open Access Journals (Sweden)

    Piórkowska Katarzyna

    2016-05-01

    Full Text Available The paper is embedded in the following fields: strategic management in terms of behavioural strategy concept, adaptability construct, and micro-foundations realm as well as organizational theory and psychology. Moreover, the paper concerns to some extent a multi-level approach in strategic management involving individual, team, and organizational level. The aim of the paper is to contribute to extend, on one hand, the ascertainment set in the field of behavioural strategy as behavioural strategy encompasses a mindboggling diversity of topics and methods and its conceptual unity has been hard to achieve (Powell, Lovallo, Fox 2011, p. 1371, and on the other hand, to order mixed approaches to adaptability especially to gain insights on micro-level adapting processes (individual adaptability and adaptive performance in terms of the multi-level approach. The method that has been used is literature studies and the interference is mostly deductive. The structure of the manuscript is four-fold. The first part involves the considerations in the field of adaptability and adaptive performance at the individual level. The issues of adaptability and adaptive performance at the team level have been presented in the second part. The third part encompasses the organizational adaptability assertions. Finally, the conclusion, limitations of the considerations highlighted as well as the future research directions have been emphasized. The overarching key finding is that the behavioural strategy concept may constitute the boundary spanner in exploring and explaining adaptability phenomenon at different levels of analysis.

  9. The Evolution of Two-Component Systems in Bacteria RevealsDifferent Strategies for Niche Adaptation

    Energy Technology Data Exchange (ETDEWEB)

    Alm, Eric; Huang, Katherine; Arkin, Adam

    2006-09-13

    Two-component systems including histidine protein kinasesrepresent the primary signal transduction paradigm in prokaryoticorganisms. To understand how these systems adapt to allow organisms todetect niche-specific signals, we analyzed the phylogenetic distributionof nearly 5000 histidine protein kinases from 207 sequenced prokaryoticgenomes. We found that many genomes carry a large repertoire of recentlyevolved signaling genes, which may reflect selective pressure to adapt tonew environmental conditions. Both lineage-specific gene family expansionand horizontal gene transfer play major roles in the introduction of newhistidine kinases into genomes; however, there are differences in howthese two evolutionary forces act. Genes imported via horizontal transferare more likely to retain their original functionality as inferred from asimilar complement of signaling domains, while gene family expansionaccompanied by domain shuffling appears to be a major source of novelgenetic diversity. Family expansion is the dominantsource of newhistidine kinase genes in the genomes most enriched in signalingproteins, and detailed analysis reveals that divergence in domainstructure and changes in expression patterns are hallmarks of recentexpansions. Finally, while these two modes of gene acquisition arewidespread across bacterial taxa, there are clear species-specificpreferences for which mode is used.

  10. Adaptive evolution in ecological communities.

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    Martin M Turcotte

    Full Text Available Understanding how natural selection drives evolution is a key challenge in evolutionary biology. Most studies of adaptation focus on how a single environmental factor, such as increased temperature, affects evolution within a single species. The biological relevance of these experiments is limited because nature is infinitely more complex. Most species are embedded within communities containing many species that interact with one another and the physical environment. To understand the evolutionary significance of such ecological complexity, experiments must test the evolutionary impact of interactions among multiple species during adaptation. Here we highlight an experiment that manipulates species composition and tracks evolutionary responses within each species, while testing for the mechanisms by which species interact and adapt to their environment. We also discuss limitations of previous studies of adaptive evolution and emphasize how an experimental evolution approach can circumvent such shortcomings. Understanding how community composition acts as a selective force will improve our ability to predict how species adapt to natural and human-induced environmental change.

  11. Adaptive evolution of molecular phenotypes

    International Nuclear Information System (INIS)

    Held, Torsten; Nourmohammad, Armita; Lässig, Michael

    2014-01-01

    Molecular phenotypes link genomic information with organismic functions, fitness, and evolution. Quantitative traits are complex phenotypes that depend on multiple genomic loci. In this paper, we study the adaptive evolution of a quantitative trait under time-dependent selection, which arises from environmental changes or through fitness interactions with other co-evolving phenotypes. We analyze a model of trait evolution under mutations and genetic drift in a single-peak fitness seascape. The fitness peak performs a constrained random walk in the trait amplitude, which determines the time-dependent trait optimum in a given population. We derive analytical expressions for the distribution of the time-dependent trait divergence between populations and of the trait diversity within populations. Based on this solution, we develop a method to infer adaptive evolution of quantitative traits. Specifically, we show that the ratio of the average trait divergence and the diversity is a universal function of evolutionary time, which predicts the stabilizing strength and the driving rate of the fitness seascape. From an information-theoretic point of view, this function measures the macro-evolutionary entropy in a population ensemble, which determines the predictability of the evolutionary process. Our solution also quantifies two key characteristics of adapting populations: the cumulative fitness flux, which measures the total amount of adaptation, and the adaptive load, which is the fitness cost due to a population's lag behind the fitness peak. (paper)

  12. Evolution of adaptation mechanisms: Adaptation energy, stress, and oscillating death.

    Science.gov (United States)

    Gorban, Alexander N; Tyukina, Tatiana A; Smirnova, Elena V; Pokidysheva, Lyudmila I

    2016-09-21

    In 1938, Selye proposed the notion of adaptation energy and published 'Experimental evidence supporting the conception of adaptation energy.' Adaptation of an animal to different factors appears as the spending of one resource. Adaptation energy is a hypothetical extensive quantity spent for adaptation. This term causes much debate when one takes it literally, as a physical quantity, i.e. a sort of energy. The controversial points of view impede the systematic use of the notion of adaptation energy despite experimental evidence. Nevertheless, the response to many harmful factors often has general non-specific form and we suggest that the mechanisms of physiological adaptation admit a very general and nonspecific description. We aim to demonstrate that Selye׳s adaptation energy is the cornerstone of the top-down approach to modelling of non-specific adaptation processes. We analyze Selye׳s axioms of adaptation energy together with Goldstone׳s modifications and propose a series of models for interpretation of these axioms. Adaptation energy is considered as an internal coordinate on the 'dominant path' in the model of adaptation. The phenomena of 'oscillating death' and 'oscillating remission' are predicted on the base of the dynamical models of adaptation. Natural selection plays a key role in the evolution of mechanisms of physiological adaptation. We use the fitness optimization approach to study of the distribution of resources for neutralization of harmful factors, during adaptation to a multifactor environment, and analyze the optimal strategies for different systems of factors. Copyright © 2016 Elsevier Ltd. All rights reserved.

  13. Expressing Adaptation Strategies Using Adaptation Patterns

    Science.gov (United States)

    Zemirline, N.; Bourda, Y.; Reynaud, C.

    2012-01-01

    Today, there is a real challenge to enable personalized access to information. Several systems have been proposed to address this challenge including Adaptive Hypermedia Systems (AHSs). However, the specification of adaptation strategies remains a difficult task for creators of such systems. In this paper, we consider the problem of the definition…

  14. Molecular evolution and thermal adaptation

    Science.gov (United States)

    Chen, Peiqiu

    2011-12-01

    In this thesis, we address problems in molecular evolution, thermal adaptation, and the kinetics of adaptation of bacteria and viruses to elevated environmental temperatures. We use a nearly neutral fitness model where the replication speed of an organism is proportional to the copy number of folded proteins. Our model reproduces the distribution of stabilities of natural proteins in excellent agreement with experiment. We find that species with high mutation rates tend to have less stable proteins compared to species with low mutation rate. We found that a broad distribution of protein stabilities observed in the model and in experiment is the key determinant of thermal response for viruses and bacteria. Our results explain most of the earlier experimental observations: striking asymmetry of thermal response curves, the absence of evolutionary trade-off which was expected but not found in experiments, correlation between denaturation temperature for several protein families and the Optimal Growth Temperature (OGT) of their carrier organisms, and proximity of bacterial or viral OGTs to their evolutionary temperatures. Our theory quantitatively and with high accuracy described thermal response curves for 35 bacterial species. The model also addresses the key to adaptation is in weak-link genes (WLG), which encode least thermodynamically stable essential proteins in the proteome. We observe, as in experiment, a two-stage adaptation process. The first stage is a Luria-Delbruck type of selection, whereby rare WLG alleles, whose proteins are more stable than WLG proteins of the majority of the population (either due to standing genetic variation or due to an early acquired mutation), rapidly rise to fixation. The second stage constitutes subsequent slow accumulation of mutations in an adapted population. As adaptation progresses, selection regime changes from positive to neutral: Selection coefficient of beneficial mutations scales as a negative power of number of

  15. Modified Covariance Matrix AdaptationEvolution Strategy algorithm for constrained optimization under uncertainty, application to rocket design

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    Chocat Rudy

    2015-01-01

    Full Text Available The design of complex systems often induces a constrained optimization problem under uncertainty. An adaptation of CMA-ES(λ, μ optimization algorithm is proposed in order to efficiently handle the constraints in the presence of noise. The update mechanisms of the parametrized distribution used to generate the candidate solutions are modified. The constraint handling method allows to reduce the semi-principal axes of the probable research ellipsoid in the directions violating the constraints. The proposed approach is compared to existing approaches on three analytic optimization problems to highlight the efficiency and the robustness of the algorithm. The proposed method is used to design a two stage solid propulsion launch vehicle.

  16. Adaptive social learning strategies in temporally and spatially varying environments : how temporal vs. spatial variation, number of cultural traits, and costs of learning influence the evolution of conformist-biased transmission, payoff-biased transmission, and individual learning.

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    Nakahashi, Wataru; Wakano, Joe Yuichiro; Henrich, Joseph

    2012-12-01

    Long before the origins of agriculture human ancestors had expanded across the globe into an immense variety of environments, from Australian deserts to Siberian tundra. Survival in these environments did not principally depend on genetic adaptations, but instead on evolved learning strategies that permitted the assembly of locally adaptive behavioral repertoires. To develop hypotheses about these learning strategies, we have modeled the evolution of learning strategies to assess what conditions and constraints favor which kinds of strategies. To build on prior work, we focus on clarifying how spatial variability, temporal variability, and the number of cultural traits influence the evolution of four types of strategies: (1) individual learning, (2) unbiased social learning, (3) payoff-biased social learning, and (4) conformist transmission. Using a combination of analytic and simulation methods, we show that spatial-but not temporal-variation strongly favors the emergence of conformist transmission. This effect intensifies when migration rates are relatively high and individual learning is costly. We also show that increasing the number of cultural traits above two favors the evolution of conformist transmission, which suggests that the assumption of only two traits in many models has been conservative. We close by discussing how (1) spatial variability represents only one way of introducing the low-level, nonadaptive phenotypic trait variation that so favors conformist transmission, the other obvious way being learning errors, and (2) our findings apply to the evolution of conformist transmission in social interactions. Throughout we emphasize how our models generate empirical predictions suitable for laboratory testing.

  17. Harmony Search Based Parameter Ensemble Adaptation for Differential Evolution

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    Rammohan Mallipeddi

    2013-01-01

    Full Text Available In differential evolution (DE algorithm, depending on the characteristics of the problem at hand and the available computational resources, different strategies combined with a different set of parameters may be effective. In addition, a single, well-tuned combination of strategies and parameters may not guarantee optimal performance because different strategies combined with different parameter settings can be appropriate during different stages of the evolution. Therefore, various adaptive/self-adaptive techniques have been proposed to adapt the DE strategies and parameters during the course of evolution. In this paper, we propose a new parameter adaptation technique for DE based on ensemble approach and harmony search algorithm (HS. In the proposed method, an ensemble of parameters is randomly sampled which form the initial harmony memory. The parameter ensemble evolves during the course of the optimization process by HS algorithm. Each parameter combination in the harmony memory is evaluated by testing them on the DE population. The performance of the proposed adaptation method is evaluated using two recently proposed strategies (DE/current-to-pbest/bin and DE/current-to-gr_best/bin as basic DE frameworks. Numerical results demonstrate the effectiveness of the proposed adaptation technique compared to the state-of-the-art DE based algorithms on a set of challenging test problems (CEC 2005.

  18. Mixed integer evolution strategies for parameter optimization.

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    Li, Rui; Emmerich, Michael T M; Eggermont, Jeroen; Bäck, Thomas; Schütz, M; Dijkstra, J; Reiber, J H C

    2013-01-01

    Evolution strategies (ESs) are powerful probabilistic search and optimization algorithms gleaned from biological evolution theory. They have been successfully applied to a wide range of real world applications. The modern ESs are mainly designed for solving continuous parameter optimization problems. Their ability to adapt the parameters of the multivariate normal distribution used for mutation during the optimization run makes them well suited for this domain. In this article we describe and study mixed integer evolution strategies (MIES), which are natural extensions of ES for mixed integer optimization problems. MIES can deal with parameter vectors consisting not only of continuous variables but also with nominal discrete and integer variables. Following the design principles of the canonical evolution strategies, they use specialized mutation operators tailored for the aforementioned mixed parameter classes. For each type of variable, the choice of mutation operators is governed by a natural metric for this variable type, maximal entropy, and symmetry considerations. All distributions used for mutation can be controlled in their shape by means of scaling parameters, allowing self-adaptation to be implemented. After introducing and motivating the conceptual design of the MIES, we study the optimality of the self-adaptation of step sizes and mutation rates on a generalized (weighted) sphere model. Moreover, we prove global convergence of the MIES on a very general class of problems. The remainder of the article is devoted to performance studies on artificial landscapes (barrier functions and mixed integer NK landscapes), and a case study in the optimization of medical image analysis systems. In addition, we show that with proper constraint handling techniques, MIES can also be applied to classical mixed integer nonlinear programming problems.

  19. Adaptive Evolution of Signaling Partners

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    Urano, Daisuke; Dong, Taoran; Bennetzen, Jeffrey L.; Jones, Alan M.

    2015-01-01

    Proteins that interact coevolve their structures. When mutation disrupts the interaction, compensation by the partner occurs to restore interaction otherwise counterselection occurs. We show in this study how a destabilizing mutation in one protein is compensated by a stabilizing mutation in its protein partner and their coevolving path. The pathway in this case and likely a general principle of coevolution is that the compensatory change must tolerate both the original and derived structures with equivalence in function and activity. Evolution of the structure of signaling elements in a network is constrained by specific protein pair interactions, by requisite conformational changes, and by catalytic activity. The heterotrimeric G protein-coupled signaling is a paragon of this protein interaction/function complexity and our deep understanding of this pathway in diverse organisms lends itself to evolutionary study. Regulators of G protein Signaling (RGS) proteins accelerate the intrinsic GTP hydrolysis rate of the Gα subunit of the heterotrimeric G protein complex. An important RGS-contact site is a hydroxyl-bearing residue on the switch I region of Gα subunits in animals and most plants, such as Arabidopsis. The exception is the grasses (e.g., rice, maize, sugarcane, millets); these plants have Gα subunits that replaced the critical hydroxyl-bearing threonine with a destabilizing asparagine shown to disrupt interaction between Arabidopsis RGS protein (AtRGS1) and the grass Gα subunit. With one known exception (Setaria italica), grasses do not encode RGS genes. One parsimonious deduction is that the RGS gene was lost in the ancestor to the grasses and then recently acquired horizontally in the lineage S. italica from a nongrass monocot. Like all investigated grasses, S. italica has the Gα subunit with the destabilizing asparagine residue in the protein interface but, unlike other known grass genomes, still encodes an expressed RGS gene, SiRGS1. SiRGS1

  20. Machine learning for evolution strategies

    CERN Document Server

    Kramer, Oliver

    2016-01-01

    This book introduces numerous algorithmic hybridizations between both worlds that show how machine learning can improve and support evolution strategies. The set of methods comprises covariance matrix estimation, meta-modeling of fitness and constraint functions, dimensionality reduction for search and visualization of high-dimensional optimization processes, and clustering-based niching. After giving an introduction to evolution strategies and machine learning, the book builds the bridge between both worlds with an algorithmic and experimental perspective. Experiments mostly employ a (1+1)-ES and are implemented in Python using the machine learning library scikit-learn. The examples are conducted on typical benchmark problems illustrating algorithmic concepts and their experimental behavior. The book closes with a discussion of related lines of research.

  1. Adaptive Evolution of Gene Expression in Drosophila

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    Armita Nourmohammad

    2017-08-01

    Full Text Available Gene expression levels are important quantitative traits that link genotypes to molecular functions and fitness. In Drosophila, population-genetic studies have revealed substantial adaptive evolution at the genomic level, but the evolutionary modes of gene expression remain controversial. Here, we present evidence that adaptation dominates the evolution of gene expression levels in flies. We show that 64% of the observed expression divergence across seven Drosophila species are adaptive changes driven by directional selection. Our results are derived from time-resolved data of gene expression divergence across a family of related species, using a probabilistic inference method for gene-specific selection. Adaptive gene expression is stronger in specific functional classes, including regulation, sensory perception, sexual behavior, and morphology. Moreover, we identify a large group of genes with sex-specific adaptation of expression, which predominantly occurs in males. Our analysis opens an avenue to map system-wide selection on molecular quantitative traits independently of their genetic basis.

  2. Directed evolution of adaptive traits

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    As a species, switchgrass is adapted to an amazingly broad range of environments, spanning hardiness zones ranging from HZ3 to HZ9 (Canada to Mexico), from the mid-grass prairie to the Atlantic Seaboard, from sandy soils to heavy clay soils, from acid to alkaline soils, and from wetland to dryland h...

  3. An Adaptive Unified Differential Evolution Algorithm for Global Optimization

    Energy Technology Data Exchange (ETDEWEB)

    Qiang, Ji; Mitchell, Chad

    2014-11-03

    In this paper, we propose a new adaptive unified differential evolution algorithm for single-objective global optimization. Instead of the multiple mutation strate- gies proposed in conventional differential evolution algorithms, this algorithm employs a single equation unifying multiple strategies into one expression. It has the virtue of mathematical simplicity and also provides users the flexibility for broader exploration of the space of mutation operators. By making all control parameters in the proposed algorithm self-adaptively evolve during the process of optimization, it frees the application users from the burden of choosing appro- priate control parameters and also improves the performance of the algorithm. In numerical tests using thirteen basic unimodal and multimodal functions, the proposed adaptive unified algorithm shows promising performance in compari- son to several conventional differential evolution algorithms.

  4. Differential Evolution Algorithm with Self-Adaptive Population Resizing Mechanism

    Directory of Open Access Journals (Sweden)

    Xu Wang

    2013-01-01

    Full Text Available A differential evolution (DE algorithm with self-adaptive population resizing mechanism, SapsDE, is proposed to enhance the performance of DE by dynamically choosing one of two mutation strategies and tuning control parameters in a self-adaptive manner. More specifically, more appropriate mutation strategies along with its parameter settings can be determined adaptively according to the previous status at different stages of the evolution process. To verify the performance of SapsDE, 17 benchmark functions with a wide range of dimensions, and diverse complexities are used. Nonparametric statistical procedures were performed for multiple comparisons between the proposed algorithm and five well-known DE variants from the literature. Simulation results show that SapsDE is effective and efficient. It also exhibits much more superiorresultsthan the other five algorithms employed in the comparison in most of the cases.

  5. Evolution of morphological and climatic adaptations in Veronica L. (Plantaginaceae

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    Jian-Cheng Wang

    2016-08-01

    Full Text Available Perennials and annuals apply different strategies to adapt to the adverse environment, based on ‘tolerance’ and ‘avoidance’, respectively. To understand lifespan evolution and its impact on plant adaptability, we carried out a comparative study of perennials and annuals in the genus Veronica from a phylogenetic perspective. The results showed that ancestors of the genus Veronicawere likely to be perennial plants. Annual life history of Veronica has evolved multiple times and subtrees with more annual species have a higher substitution rate. Annuals can adapt to more xeric habitats than perennials. This indicates that annuals are more drought-resistant than their perennial relatives. Due to adaptation to similar selective pressures, parallel evolution occurs in morphological characters among annual species of Veronica.

  6. Blackboxing: social learning strategies and cultural evolution.

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    Heyes, Cecilia

    2016-05-05

    Social learning strategies (SLSs) enable humans, non-human animals, and artificial agents to make adaptive decisions aboutwhenthey should copy other agents, andwhothey should copy. Behavioural ecologists and economists have discovered an impressive range of SLSs, and explored their likely impact on behavioural efficiency and reproductive fitness while using the 'phenotypic gambit'; ignoring, or remaining deliberately agnostic about, the nature and origins of the cognitive processes that implement SLSs. Here I argue that this 'blackboxing' of SLSs is no longer a viable scientific strategy. It has contributed, through the 'social learning strategies tournament', to the premature conclusion that social learning is generally better than asocial learning, and to a deep puzzle about the relationship between SLSs and cultural evolution. The puzzle can be solved by recognizing that whereas most SLSs are 'planetary'--they depend on domain-general cognitive processes--some SLSs, found only in humans, are 'cook-like'--they depend on explicit, metacognitive rules, such ascopy digital natives. These metacognitive SLSs contribute to cultural evolution by fostering the development of processes that enhance the exclusivity, specificity, and accuracy of social learning. © 2016 The Author(s).

  7. Blackboxing: social learning strategies and cultural evolution

    Science.gov (United States)

    Heyes, Cecilia

    2016-01-01

    Social learning strategies (SLSs) enable humans, non-human animals, and artificial agents to make adaptive decisions about when they should copy other agents, and who they should copy. Behavioural ecologists and economists have discovered an impressive range of SLSs, and explored their likely impact on behavioural efficiency and reproductive fitness while using the ‘phenotypic gambit’; ignoring, or remaining deliberately agnostic about, the nature and origins of the cognitive processes that implement SLSs. Here I argue that this ‘blackboxing' of SLSs is no longer a viable scientific strategy. It has contributed, through the ‘social learning strategies tournament', to the premature conclusion that social learning is generally better than asocial learning, and to a deep puzzle about the relationship between SLSs and cultural evolution. The puzzle can be solved by recognizing that whereas most SLSs are ‘planetary'—they depend on domain-general cognitive processes—some SLSs, found only in humans, are ‘cook-like'—they depend on explicit, metacognitive rules, such as copy digital natives. These metacognitive SLSs contribute to cultural evolution by fostering the development of processes that enhance the exclusivity, specificity, and accuracy of social learning. PMID:27069046

  8. Adaptation, plant evolution, and the fossil record

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    Knoll, A. H.; Niklas, K. J.

    1987-01-01

    The importance of adaptation in determining patterns of evolution has become an important focus of debate in evolutionary biology. As it pertains to paleobotany, the issue is whether or not adaptive evolution mediated by natural selection is sufficient to explain the stratigraphic distributions of taxa and character states observed in the plant fossil record. One means of addressing this question is the functional evaluation of stratigraphic series of plant organs set in the context of paleoenvironmental change and temporal patterns of floral composition within environments. For certain organ systems, quantitative estimates of biophysical performance can be made on the basis of structures preserved in the fossil record. Performance estimates for plants separated in time or space can be compared directly. Implicit in different hypotheses of the forces that shape the evolutionary record (e.g. adaptation, mass extinction, rapid environmental change, chance) are predictions about stratigraphic and paleoenvironmental trends in the efficacy of functional performance. Existing data suggest that following the evolution of a significant structural innovation, adaptation for improved functional performance can be a major determinant of evolutionary changes in plants; however, there are structural and development limits to functional improvement, and once these are reached, the structure in question may no longer figure strongly in selection until and unless a new innovation evolves. The Silurian-Devonian paleobotanical record is consistent with the hypothesis that the succession of lowland floodplain dominants preserved in the fossil record of this interval was determined principally by the repeated evolution of new taxa that rose to ecological importance because of competitive advantages conferred by improved biophysical performance. This does not seem to be equally true for Carboniferous-Jurassic dominants of swamp and lowland floodplain environments. In these cases

  9. Effective Strategies for Teaching Evolution: The Primary Evolution Project

    Science.gov (United States)

    Hatcher, Chris

    2015-01-01

    When Chris Hatcher joined the Primary Evolution Project team at the University of Reading, his goal was to find effective strategies to teach evolution in a way that keeps children engaged and enthused. Hatcher has collaborated with colleagues at the University's Institute of Education to break the evolution unit down into distinct topics and…

  10. Adaptive Evolution of Gene Expression in Drosophila.

    Science.gov (United States)

    Nourmohammad, Armita; Rambeau, Joachim; Held, Torsten; Kovacova, Viera; Berg, Johannes; Lässig, Michael

    2017-08-08

    Gene expression levels are important quantitative traits that link genotypes to molecular functions and fitness. In Drosophila, population-genetic studies have revealed substantial adaptive evolution at the genomic level, but the evolutionary modes of gene expression remain controversial. Here, we present evidence that adaptation dominates the evolution of gene expression levels in flies. We show that 64% of the observed expression divergence across seven Drosophila species are adaptive changes driven by directional selection. Our results are derived from time-resolved data of gene expression divergence across a family of related species, using a probabilistic inference method for gene-specific selection. Adaptive gene expression is stronger in specific functional classes, including regulation, sensory perception, sexual behavior, and morphology. Moreover, we identify a large group of genes with sex-specific adaptation of expression, which predominantly occurs in males. Our analysis opens an avenue to map system-wide selection on molecular quantitative traits independently of their genetic basis. Copyright © 2017 The Authors. Published by Elsevier Inc. All rights reserved.

  11. Farming System Evolution and Adaptive Capacity: Insights for Adaptation Support

    Directory of Open Access Journals (Sweden)

    Jami L. Dixon

    2014-02-01

    Full Text Available Studies of climate impacts on agriculture and adaptation often provide current or future assessments, ignoring the historical contexts farming systems are situated within. We investigate how historical trends have influenced farming system adaptive capacity in Uganda using data from household surveys, semi-structured interviews, focus-group discussions and observations. By comparing two farming systems, we note three major findings: (1 similar trends in farming system evolution have had differential impacts on the diversity of farming systems; (2 trends have contributed to the erosion of informal social and cultural institutions and an increasing dependence on formal institutions; and (3 trade-offs between components of adaptive capacity are made at the farm-scale, thus influencing farming system adaptive capacity. To identify the actual impacts of future climate change and variability, it is important to recognize the dynamic nature of adaptation. In practice, areas identified for further adaptation support include: shift away from one-size-fits-all approach the identification and integration of appropriate modern farming method; a greater focus on building inclusive formal and informal institutions; and a more nuanced understanding regarding the roles and decision-making processes of influential, but external, actors. More research is needed to understand farm-scale trade-offs and the resulting impacts across spatial and temporal scales.

  12. Adapting Digital Libraries to Continual Evolution

    Science.gov (United States)

    Barkstrom, Bruce R.; Finch, Melinda; Ferebee, Michelle; Mackey, Calvin

    2002-01-01

    In this paper, we describe five investment streams (data storage infrastructure, knowledge management, data production control, data transport and security, and personnel skill mix) that need to be balanced against short-term operating demands in order to maximize the probability of long-term viability of a digital library. Because of the rapid pace of information technology change, a digital library cannot be a static institution. Rather, it has to become a flexible organization adapted to continuous evolution of its infrastructure.

  13. Adaptive evolution of transcription factor binding sites

    Directory of Open Access Journals (Sweden)

    Berg Johannes

    2004-10-01

    Full Text Available Abstract Background The regulation of a gene depends on the binding of transcription factors to specific sites located in the regulatory region of the gene. The generation of these binding sites and of cooperativity between them are essential building blocks in the evolution of complex regulatory networks. We study a theoretical model for the sequence evolution of binding sites by point mutations. The approach is based on biophysical models for the binding of transcription factors to DNA. Hence we derive empirically grounded fitness landscapes, which enter a population genetics model including mutations, genetic drift, and selection. Results We show that the selection for factor binding generically leads to specific correlations between nucleotide frequencies at different positions of a binding site. We demonstrate the possibility of rapid adaptive evolution generating a new binding site for a given transcription factor by point mutations. The evolutionary time required is estimated in terms of the neutral (background mutation rate, the selection coefficient, and the effective population size. Conclusions The efficiency of binding site formation is seen to depend on two joint conditions: the binding site motif must be short enough and the promoter region must be long enough. These constraints on promoter architecture are indeed seen in eukaryotic systems. Furthermore, we analyse the adaptive evolution of genetic switches and of signal integration through binding cooperativity between different sites. Experimental tests of this picture involving the statistics of polymorphisms and phylogenies of sites are discussed.

  14. Evolution of Genetic Variance during Adaptive Radiation.

    Science.gov (United States)

    Walter, Greg M; Aguirre, J David; Blows, Mark W; Ortiz-Barrientos, Daniel

    2018-04-01

    Genetic correlations between traits can concentrate genetic variance into fewer phenotypic dimensions that can bias evolutionary trajectories along the axis of greatest genetic variance and away from optimal phenotypes, constraining the rate of evolution. If genetic correlations limit adaptation, rapid adaptive divergence between multiple contrasting environments may be difficult. However, if natural selection increases the frequency of rare alleles after colonization of new environments, an increase in genetic variance in the direction of selection can accelerate adaptive divergence. Here, we explored adaptive divergence of an Australian native wildflower by examining the alignment between divergence in phenotype mean and divergence in genetic variance among four contrasting ecotypes. We found divergence in mean multivariate phenotype along two major axes represented by different combinations of plant architecture and leaf traits. Ecotypes also showed divergence in the level of genetic variance in individual traits and the multivariate distribution of genetic variance among traits. Divergence in multivariate phenotypic mean aligned with divergence in genetic variance, with much of the divergence in phenotype among ecotypes associated with changes in trait combinations containing substantial levels of genetic variance. Overall, our results suggest that natural selection can alter the distribution of genetic variance underlying phenotypic traits, increasing the amount of genetic variance in the direction of natural selection and potentially facilitating rapid adaptive divergence during an adaptive radiation.

  15. Strategy for Climate Change Adaptation

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2013-01-01

    . This absence of an agreement calls for adaptation to climate change. Emphasis should be put on buildings, as they play a vital economic and social role in society and are vulnerable to climate change. Therefore, the building stock deserves its own policy and implementation plans as well as tools that enable...... adequate and cost-efficient adaptation to climate change. This paper explains the need for climate change adaptation of the building stock and suggests a pattern for a strategic approach to how to reach the climate change adaptation needed. The suggested and presented need of a strategic approach is based...... on three main initiatives consisting of the need to examine the potential impacts of climate change on the building stock, the need to assess and develop a roadmap of current and future adaptation measures that can withstand the effects of climate change, and the need to engage relevant stakeholders...

  16. Strategy for Climate Change Adaptation

    DEFF Research Database (Denmark)

    Rasmussen, Torben Valdbjørn

    2014-01-01

    . This absence of an agreement calls for adaptation to climate change. Emphasis should be put on buildings, as they play a vital economic and social role in society and are vulnerable to climate change. Therefore, the building stock deserves its own policy and implementation plans as well as tools that enable...... adequate and cost-efficient adaptation to climate change. This paper explains the need for climate change adaptation of the building stock and suggests a pattern for a strategic approach to how to reach the climate change adaptation needed. The suggested and presented need of a strategic approach is based...... on three main initiatives consisting of the need to examine the potential impacts of climate change on the building stock, the need to assess and develop a roadmap of current and future adaptation measures that can withstand the effects of climate change, and the need to engage relevant stakeholders...

  17. An Efficient Binary Differential Evolution with Parameter Adaptation

    Directory of Open Access Journals (Sweden)

    Dongli Jia

    2013-04-01

    Full Text Available Differential Evolution (DE has been applied to many scientific and engineering problems for its simplicity and efficiency. However, the standard DE cannot be used in a binary search space directly. This paper proposes an adaptive binary Differential Evolution algorithm, or ABDE, that has a similar framework as the standard DE but with an improved binary mutation strategy in which the best individual participates. To further enhance the search ability, the parameters of the ABDE are slightly disturbed in an adaptive manner. Experiments have been carried out by comparing ABDE with two binary DE variants, normDE and BDE, and the most used binary search technique, GA, on a set of 13 selected benchmark functions and the classical 0-1 knapsack problem. Results show that the ABDE performs better than, or at least comparable to, the other algorithms in terms of search ability, convergence speed, and solution accuracy.

  18. DECISION STRATEGIES AND COGNITIVE ADAPTATIONS TO ECOLOGY

    Directory of Open Access Journals (Sweden)

    Poleszczuk Jan

    2017-06-01

    Full Text Available In this paper, I discuss the concept of adaptive rationality. I present a simple model of ecology and the set of decision rules. The basic structure of the process of cognitive adaptation to ecology is described as a structure comprising (1 perceptual space, (2 a function valuating perceived items, (3 a set of available decision rules and (4 the adaptation process - identification and selection of the best strategies in given ecological conditions. The presented model of ecosystem allows a conclusion that completely opposite strategies may be compatible with the assumption of adaptive rationality.

  19. Efficient receiver tuning using differential evolution strategies

    Science.gov (United States)

    Wheeler, Caleb H.; Toland, Trevor G.

    2016-08-01

    Differential evolution (DE) is a powerful and computationally inexpensive optimization strategy that can be used to search an entire parameter space or to converge quickly on a solution. The Kilopixel Array Pathfinder Project (KAPPa) is a heterodyne receiver system delivering 5 GHz of instantaneous bandwidth in the tuning range of 645-695 GHz. The fully automated KAPPa receiver test system finds optimal receiver tuning using performance feedback and DE. We present an adaptation of DE for use in rapid receiver characterization. The KAPPa DE algorithm is written in Python 2.7 and is fully integrated with the KAPPa instrument control, data processing, and visualization code. KAPPa develops the technologies needed to realize heterodyne focal plane arrays containing 1000 pixels. Finding optimal receiver tuning by investigating large parameter spaces is one of many challenges facing the characterization phase of KAPPa. This is a difficult task via by-hand techniques. Characterizing or tuning in an automated fashion without need for human intervention is desirable for future large scale arrays. While many optimization strategies exist, DE is ideal for time and performance constraints because it can be set to converge to a solution rapidly with minimal computational overhead. We discuss how DE is utilized in the KAPPa system and discuss its performance and look toward the future of 1000 pixel array receivers and consider how the KAPPa DE system might be applied.

  20. Biodiversity, evolution and adaptation of cultivated crops.

    Science.gov (United States)

    Vigouroux, Yves; Barnaud, Adeline; Scarcelli, Nora; Thuillet, Anne-Céline

    2011-05-01

    The human diet depends on very few crops. Current diversity in these crops is the result of a long interaction between farmers and cultivated plants, and their environment. Man largely shaped crop biodiversity from the domestication period 12,000 B.P. to the development of improved varieties during the last century. We illustrate this process through a detailed analysis of the domestication and early diffusion of maize. In smallholder agricultural systems, farmers still have a major impact on crop diversity today. We review several examples of the major impact of man on current diversity. Finally, biodiversity is considered to be an asset for adaptation to current environmental changes. We describe the evolution of pearl millet in West Africa, where average rainfall has decreased over the last forty years. Diversity in cultivated varieties has certainly helped this crop to adapt to climate variation. Copyright © 2011 Académie des sciences. Published by Elsevier SAS. All rights reserved.

  1. Epistatic adaptive evolution of human color vision.

    Directory of Open Access Journals (Sweden)

    Shozo Yokoyama

    2014-12-01

    Full Text Available Establishing genotype-phenotype relationship is the key to understand the molecular mechanism of phenotypic adaptation. This initial step may be untangled by analyzing appropriate ancestral molecules, but it is a daunting task to recapitulate the evolution of non-additive (epistatic interactions of amino acids and function of a protein separately. To adapt to the ultraviolet (UV-free retinal environment, the short wavelength-sensitive (SWS1 visual pigment in human (human S1 switched from detecting UV to absorbing blue light during the last 90 million years. Mutagenesis experiments of the UV-sensitive pigment in the Boreoeutherian ancestor show that the blue-sensitivity was achieved by seven mutations. The experimental and quantum chemical analyses show that 4,008 of all 5,040 possible evolutionary trajectories are terminated prematurely by containing a dehydrated nonfunctional pigment. Phylogenetic analysis further suggests that human ancestors achieved the blue-sensitivity gradually and almost exclusively by epistasis. When the final stage of spectral tuning of human S1 was underway 45-30 million years ago, the middle and long wavelength-sensitive (MWS/LWS pigments appeared and so-called trichromatic color vision was established by interprotein epistasis. The adaptive evolution of human S1 differs dramatically from orthologous pigments with a major mutational effect used in achieving blue-sensitivity in a fish and several mammalian species and in regaining UV vision in birds. These observations imply that the mechanisms of epistatic interactions must be understood by studying various orthologues in different species that have adapted to various ecological and physiological environments.

  2. Adaptation strategies in the Netherlands

    NARCIS (Netherlands)

    Gupta, J.; Klostermann, J.E.M.; Bergsma, E.; Jong, P.; Albrecht, E.; Schmidt, M.; Mißler-Behr, M.; Spyra, S.P.N.

    2014-01-01

    Although climate change has been prominently featured on the global scientific and political agendas since the World Climate Conference in 1979 (WCC 1979), the specific importance of adaptation to climate change has only been underlined about 20 years later. The Netherlands, because it lies largely

  3. Strategy intervention for the evolution of fairness.

    Directory of Open Access Journals (Sweden)

    Yanling Zhang

    Full Text Available The 'irrational' preference for fairness has attracted increasing attention. Although previous studies have focused on the effects of spitefulness on the evolution of fairness, they did not consider non-monotonic rejections shown in behavioral experiments. In this paper, we introduce a non-monotonic rejection in an evolutionary model of the Ultimatum Game. We propose strategy intervention to study the evolution of fairness in general structured populations. By sequentially adding five strategies into the competition between a fair strategy and a selfish strategy, we arrive at the following conclusions. First, the evolution of fairness is inhibited by altruism, but it is promoted by spitefulness. Second, the non-monotonic rejection helps fairness overcome selfishness. Particularly for group-structured populations, we analytically investigate how fairness, selfishness, altruism, and spitefulness are affected by population size, mutation, and migration in the competition among seven strategies. Our results may provide important insights into understanding the evolutionary origin of fairness.

  4. Evolution of Cooperation in Adaptive Social Networks

    Science.gov (United States)

    Segbroeck, Sven Van; Santos, Francisco C.; Traulsen, Arne; Lenaerts, Tom; Pacheco, Jorge M.

    Humans are organized in societies, a phenomenon that would never have been possible without the evolution of cooperative behavior. Several mechanisms that foster this evolution have been unraveled over the years, with population structure as a prominent promoter of cooperation. Modern networks of exchange and cooperation are, however, becoming increasingly volatile, and less and less based on long-term stable structure. Here, we address how this change of paradigm aspects the evolution of cooperation. We discuss analytical and numerical models in which individuals can break social ties and create new ones. Interactions are modeled as two-player dilemmas of cooperation. Once a link between two individuals has formed, the productivity of this link is evaluated. Links can be broken off at different rates. This individual capacity of forming new links or severing inconvenient ones can effectively change the nature of the game. We address random formation of new links and local linking rules as well as different individual capacities to maintain social interactions. We conclude by discussing how adaptive social networks can become an important step towards more realistic models of cultural dynamics.

  5. Adaptive CGFs Based on Grammatical Evolution

    Directory of Open Access Journals (Sweden)

    Jian Yao

    2015-01-01

    Full Text Available Computer generated forces (CGFs play blue or red units in military simulations for personnel training and weapon systems evaluation. Traditionally, CGFs are controlled through rule-based scripts, despite the doctrine-driven behavior of CGFs being rigid and predictable. Furthermore, CGFs are often tricked by trainees or fail to adapt to new situations (e.g., changes in battle field or update in weapon systems, and, in most cases, the subject matter experts (SMEs review and redesign a large amount of CGF scripts for new scenarios or training tasks, which is both challenging and time-consuming. In an effort to overcome these limitations and move toward more true-to-life scenarios, a study using grammatical evolution (GE to generate adaptive CGFs for air combat simulations has been conducted. Expert knowledge is encoded with modular behavior trees (BTs for compatibility with the operators in genetic algorithm (GA. GE maps CGFs, represented with BTs to binary strings, and uses GA to evolve CGFs with performance feedback from the simulation. Beyond-visual-range air combat experiments between adaptive CGFs and nonadaptive baseline CGFs have been conducted to observe and study this evolutionary process. The experimental results show that the GE is an efficient framework to generate CGFs in BTs formalism and evolve CGFs via GA.

  6. Pervasive Adaptive Evolution in Primate Seminal Proteins.

    Directory of Open Access Journals (Sweden)

    2005-09-01

    Full Text Available Seminal fluid proteins show striking effects on reproduction, involving manipulation of female behavior and physiology, mechanisms of sperm competition, and pathogen defense. Strong adaptive pressures are expected for such manifestations of sexual selection and host defense, but the extent of positive selection in seminal fluid proteins from divergent taxa is unknown. We identified adaptive evolution in primate seminal proteins using genomic resources in a tissue-specific study. We found extensive signatures of positive selection when comparing 161 human seminal fluid proteins and 2,858 prostate-expressed genes to those in chimpanzee. Seven of eight outstanding genes yielded statistically significant evidence of positive selection when analyzed in divergent primates. Functional clues were gained through divergent analysis, including several cases of species-specific loss of function in copulatory plug genes, and statistically significant spatial clustering of positively selected sites near the active site of kallikrein 2. This study reveals previously unidentified positive selection in seven primate seminal proteins, and when considered with findings in Drosophila, indicates that extensive positive selection is found in seminal fluid across divergent taxonomic groups.

  7. CBCT-guided evolutive library for cervical adaptive IMRT.

    Science.gov (United States)

    Rigaud, Bastien; Simon, Antoine; Gobeli, Maxime; Lafond, Caroline; Leseur, Julie; Barateau, Anais; Jaksic, Nicolas; Castelli, Joël; Williaume, Danièle; Haigron, Pascal; De Crevoisier, Renaud

    2018-04-01

    In the context of adaptive radiation therapy (ART) for locally advanced cervical carcinoma (LACC), this study proposed an original cone-beam computed tomography (CBCT)-guided "Evolutive library" and evaluated it against four other known radiotherapy (RT) strategies. For 20 patients who underwent intensity-modulated radiation therapy (IMRT) for LACC, three planning CTs [with empty (EB), intermediate (IB), and full (FB) bladder volumes], a CT scan at 20 Gy and bi-weekly CBCTs for 5 weeks were performed. Five RT strategies were simulated for each patient: "Standard RT" was based on one IB planning CT; "internal target volume (ITV)-based RT" was an ITV built from the three planning CTs; "RT with one mid-treatment replanning (MidTtReplan)" corresponded to the standard RT with a replanning at 20 Gy; "Pretreatment library ART" using a planning library based on the three planning CTs; and the "Evolutive library ART", which was the "Pretreatment library ART" strategy enriched by including some CBCT anatomies into the library when the daily clinical target volume (CTV) shape differed from the ones in the library. Two planning target volume (PTV) margins of 7 and 10 mm were evaluated. All the strategies were geometrically compared in terms of the percentage of coverage by the PTV, for the CTV and the organs at risk (OAR) delineated on the CBCT. Inadequate coverage of the CTV and OARs by the PTV was also assessed using deformable image registration. The cumulated dose distributions of each strategy were likewise estimated and compared for one patient. The "Evolutive library ART" strategy involved a number of added CBCTs: 0 for 55%; 1 for 30%; 2 for 5%; and 3 for 10% of patients. Compared with the other four, this strategy provided the highest CTV geometric coverage by the PTV, with a mean (min-max) coverage of 98.5% (96.4-100) for 10 mm margins and 96.2% (93.0-99.7) for 7 mm margins (P < 0.05). Moreover, this strategy significantly decreased the geometric coverage of the bowel

  8. Helsinki Metropolitan Area Climate Change Adaptation Strategy

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-07-01

    The Helsinki Metropolitan Area Climate Change Adaptation Strategy has been prepared in close cooperation with the four cities of the metropolitan area (Helsinki, Espoo, Vantaa and Kauniainen), the Helsinki Region Environmental Services Authority HSY and other municipal, regional and state level organisations. In the strategy, strategic starting points and policies with which the metropolitan area prepares for the consequences of climate change, are compiled. The Helsinki Metropolitan Area adaptation strategy concentrates on the adaptation of the built and urban environment to the changing climate. The vision of the strategy is climate proof city - the future is built now. The strategy aims to (1) assess the impacts of climate change in the area, (2) prepare for the impacts of climate change and to extreme weather events and (3) to reduce the vulnerabilities of the area to climate variability and change. The target is to secure the well-being of the citizens and the functioning of the cities also in the changing climate conditions. The preparation of the adaptation strategy started in 2009 by producing the background studies. They include the regional climate and sea level scenarios, modelling of river floods in climate change conditions and a survey of climate change impacts in the region. Also, existing programmes, legislation, research and studies concerning adaptation were collected. The background studies are published in a report titled 'The Helsinki metropolitan area climate is changing - Adaptation strategy background studies' (in Finnish) (HSY 2010). HSY coordinated the strategy preparation. The work was carried out is close cooperation with the experts of the metropolitan area cities, regional emergency services, Ministry of the Environment, Helsinki Region Transport Authority and other regional organisations. The strategy work has had a steering group that consists of representatives of the cities and other central cooperation partners. The

  9. Improving cellulase production by Aspergillus niger using adaptive evolution

    NARCIS (Netherlands)

    Patyshakuliyeva, Aleksandrina; Arentshorst, Mark; Allijn, Iris E; Ram, Arthur F J; de Vries, Ronald P; Gelber, Isabelle Benoit

    OBJECTIVES: To evaluate the potential of adaptive evolution as a tool in generating strains with an improved production of plant biomass degrading enzymes. RESULTS: An Aspergillus niger cellulase mutant was obtained by adaptive evolution. Physiological properties of this mutant revealed a five times

  10. Climate changes and farmers' endogenous adaptation strategies ...

    African Journals Online (AJOL)

    It has been claimed that climate changes impact studies often assume certain adaptations and little explicit examination of how, when, why, and under what conditions they occur. This research aims at analysing the endogenous strategies developed by farmers in agricultural land and crop management. With random ...

  11. [Adaptation strategies faced with chronic pain].

    Science.gov (United States)

    Bioy, Antoine

    2017-05-01

    Chronic pain constitutes a challenge for patients. It makes them uneasy with regard to their personality, their corporality and their life balance, and leaves long-lasting effects on their experience as a patient. The development of adaptation strategies and resources to deal with chronic pain is therefore essential. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

  12. Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes.

    Science.gov (United States)

    Christie, Joshua R; Beekman, Madeleine

    2017-03-01

    Eukaryotes carry numerous asexual cytoplasmic genomes (mitochondria and plastids). Lacking recombination, asexual genomes should theoretically suffer from impaired adaptive evolution. Yet, empirical evidence indicates that cytoplasmic genomes experience higher levels of adaptive evolution than predicted by theory. In this study, we use a computational model to show that the unique biology of cytoplasmic genomes-specifically their organization into host cells and their uniparental (maternal) inheritance-enable them to undergo effective adaptive evolution. Uniparental inheritance of cytoplasmic genomes decreases competition between different beneficial substitutions (clonal interference), promoting the accumulation of beneficial substitutions. Uniparental inheritance also facilitates selection against deleterious cytoplasmic substitutions, slowing Muller's ratchet. In addition, uniparental inheritance generally reduces genetic hitchhiking of deleterious substitutions during selective sweeps. Overall, uniparental inheritance promotes adaptive evolution by increasing the level of beneficial substitutions relative to deleterious substitutions. When we assume that cytoplasmic genome inheritance is biparental, decreasing the number of genomes transmitted during gametogenesis (bottleneck) aids adaptive evolution. Nevertheless, adaptive evolution is always more efficient when inheritance is uniparental. Our findings explain empirical observations that cytoplasmic genomes-despite their asexual mode of reproduction-can readily undergo adaptive evolution. © The Author 2016. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  13. National strategy for climate change adaptation

    International Nuclear Information System (INIS)

    2010-01-01

    This book expresses the French State's view on the way to deal with the issue of climate change adaptation. After having recalled the ineluctability of some observed changes, the actors involved in this adaptation, and some guideline principles to implement adaptation, a first chapter describes the context: international mobilization, climate data evolution, definition of new criteria and critical thresholds, relationship between adaptation, alleviation and sustainable development, tensions between long and short terms. It discusses the objectives: public security and health, alleviation of inequalities with respect to risks, cost reduction, natural heritage preservation. Nine strategic axes are then identified: to develop knowledge, to strengthen the survey system, to inform, to educate and to make all actors aware, to promote a territory-based approach, to finance adaptation actions, to use regulatory and law instruments, to support voluntary approaches and the dialogue with private actors, to take the overseas peculiarity into account, and to contribute to international exchanges. The next chapters are respectively dealing with transverse approaches (water, risk prevention, health, and biodiversity), sector-based insights (agriculture, energy and industry, transports, building and housing, tourism, banks and insurance companies), medium-based approach (cities, littoral and seas, mountain, forest). The last part deals with the implementation issue

  14. Uniparental Inheritance Promotes Adaptive Evolution in Cytoplasmic Genomes

    Science.gov (United States)

    Christie, Joshua R.; Beekman, Madeleine

    2017-01-01

    Eukaryotes carry numerous asexual cytoplasmic genomes (mitochondria and plastids). Lacking recombination, asexual genomes should theoretically suffer from impaired adaptive evolution. Yet, empirical evidence indicates that cytoplasmic genomes experience higher levels of adaptive evolution than predicted by theory. In this study, we use a computational model to show that the unique biology of cytoplasmic genomes—specifically their organization into host cells and their uniparental (maternal) inheritance—enable them to undergo effective adaptive evolution. Uniparental inheritance of cytoplasmic genomes decreases competition between different beneficial substitutions (clonal interference), promoting the accumulation of beneficial substitutions. Uniparental inheritance also facilitates selection against deleterious cytoplasmic substitutions, slowing Muller’s ratchet. In addition, uniparental inheritance generally reduces genetic hitchhiking of deleterious substitutions during selective sweeps. Overall, uniparental inheritance promotes adaptive evolution by increasing the level of beneficial substitutions relative to deleterious substitutions. When we assume that cytoplasmic genome inheritance is biparental, decreasing the number of genomes transmitted during gametogenesis (bottleneck) aids adaptive evolution. Nevertheless, adaptive evolution is always more efficient when inheritance is uniparental. Our findings explain empirical observations that cytoplasmic genomes—despite their asexual mode of reproduction—can readily undergo adaptive evolution. PMID:28025277

  15. Nutritional strategies to influence adaptations to training.

    Science.gov (United States)

    Spriet, Lawrence L; Gibala, Martin J

    2004-01-01

    This article highlights new nutritional concerns or practices that may influence the adaptation to training. The discussion is based on the assumption that the adaptation to repeated bouts of training occurs during recovery periods and that if one can train harder, the adaptation will be greater. The goal is to maximize with nutrition the recovery/adaptation that occurs in all rest periods, such that recovery before the next training session is complete. Four issues have been identified where recent scientific information will force sports nutritionists to embrace new issues and reassess old issues and, ultimately, alter the nutritional recommendations they give to athletes. These are: (1) caffeine ingestion; (2) creatine ingestion; (3) the use of intramuscular triacylglycerol (IMTG) as a fuel during exercise and the nutritional effects on IMTG repletion following exercise; and (4) the role nutrition may play in regulating the expression of genes during and after exercise training sessions. Recent findings suggest that low doses of caffeine exert significant ergogenic effects by directly affecting the central nervous system during exercise. Caffeine can cross the blood-brain barrier and antagonize the effects of adenosine, resulting in higher concentrations of stimulatory neurotransmitters. These new data strengthen the case for using low doses of caffeine during training. On the other hand, the data on the role that supplemental creatine ingestion plays in augmenting the increase in skeletal muscle mass and strength during resistance training remain equivocal. Some studies are able to demonstrate increases in muscle fibre size with creatine ingestion and some are not. The final two nutritional topics are new and have not progressed to the point that we can specifically identify strategies to enhance the adaptation to training. However, it is likely that nutritional strategies will be needed to replenish the IMTG that is used during endurance exercise. It is not

  16. Funding climate adaptation strategies with climate derivatives

    Directory of Open Access Journals (Sweden)

    L. Richard Little

    2015-01-01

    Full Text Available Climate adaptation requires large capital investments that could be provided not only by traditional sources like governments and banks, but also by derivatives markets. Such markets would allow two parties with different tolerances and expectations about climate risks to transact for their mutual benefit and, in so doing, finance climate adaptation. Here we calculate the price of a derivative called a European put option, based on future sea surface temperature (SST in Tasmania, Australia, with an 18 °C strike threshold. This price represents a quantifiable indicator of climate risk, and forms the basis for aquaculture industries exposed to the risk of higher SST to finance adaptation strategies through the sale of derivative contracts. Such contracts provide a real incentive to parties with different climate outlooks, or risk exposure to take a market assessment of climate change.

  17. Design strategies for irregularly adapting parallel applications

    International Nuclear Information System (INIS)

    Oliker, Leonid; Biswas, Rupak; Shan, Hongzhang; Sing, Jaswinder Pal

    2000-01-01

    Achieving scalable performance for dynamic irregular applications is eminently challenging. Traditional message-passing approaches have been making steady progress towards this goal; however, they suffer from complex implementation requirements. The use of a global address space greatly simplifies the programming task, but can degrade the performance of dynamically adapting computations. In this work, we examine two major classes of adaptive applications, under five competing programming methodologies and four leading parallel architectures. Results indicate that it is possible to achieve message-passing performance using shared-memory programming techniques by carefully following the same high level strategies. Adaptive applications have computational work loads and communication patterns which change unpredictably at runtime, requiring dynamic load balancing to achieve scalable performance on parallel machines. Efficient parallel implementations of such adaptive applications are therefore a challenging task. This work examines the implementation of two typical adaptive applications, Dynamic Remeshing and N-Body, across various programming paradigms and architectural platforms. We compare several critical factors of the parallel code development, including performance, programmability, scalability, algorithmic development, and portability

  18. ADAPTIVE STRATEGIES OF THE HALOPHYTE POPULATIONS

    Directory of Open Access Journals (Sweden)

    O. Z. Glukhov

    2013-11-01

    Full Text Available Studies of the adaptive strategies of halophytes at different levels of their organization are important not only for assessment of their health condition and prognosticating their future behaviors, but also for testing potential suitability of technogenic edaphotopes for plant growth without making additional analyses. We investigated the population structure and morphological variation of three halophilic Gypsophyla L. species which actively spread in different technogenic ecotopes of Ukraine by methods generally accepted in ecology and phytocenology. By the type of strategy populations of species of the genus Gypsophila in technogenic edaphotopes can change the primary type of strategy for the secondary, or gain the stress-tolerant type, mainly due to the changes of parameters of seed productivity. The studied populations are stable with predominance of individuals which reached the prereproductive and reproductive stages of their development. At the organism level the species differ by phenotypic plasticity revealing in compensatory development of vegetative and generative organs. This reflects not only in absolute values of parameters of features, but also when calculating the coefficients of divergence, variation, as well as the vitality classes in populations.By the adaptive strategy halophytes are candidates for use in local phytoremediation of disturbed lands.

  19. Inertia in strategy switching transforms the strategy evolution.

    Science.gov (United States)

    Zhang, Yanling; Fu, Feng; Wu, Te; Xie, Guangming; Wang, Long

    2011-12-01

    A recent experimental study [Traulsen et al., Proc. Natl. Acad. Sci. 107, 2962 (2010)] shows that human strategy updating involves both direct payoff comparison and the cost of switching strategy, which is equivalent to inertia. However, it remains largely unclear how such a predisposed inertia affects 2 × 2 games in a well-mixed population of finite size. To address this issue, the "inertia bonus" (strategy switching cost) is added to the learner payoff in the Fermi process. We find how inertia quantitatively shapes the stationary distribution and that stochastic stability under inertia exhibits three regimes, with each covering seven regions in the plane spanned by two inertia parameters. We also obtain the extended "1/3" rule with inertia and the speed criterion with inertia; these two findings hold for a population above two. We illustrate the above results in the framework of the Prisoner's Dilemma game. As inertia varies, two intriguing stationary distributions emerge: the probability of coexistence state is maximized, or those of two full states are simultaneously peaked. Our results may provide useful insights into how the inertia of changing status quo acts on the strategy evolution and, in particular, the evolution of cooperation.

  20. Efficient community-based control strategies in adaptive networks

    International Nuclear Information System (INIS)

    Yang Hui; Tang Ming; Zhang Haifeng

    2012-01-01

    Most studies on adaptive networks concentrate on the properties of steady state, but neglect transient dynamics. In this study, we pay attention to the emergence of community structure in the transient process and the effects of community-based control strategies on epidemic spreading. First, by normalizing the modularity, we investigate the evolution of community structure during the transient process, and find that a strong community structure is induced by the rewiring mechanism in the early stage of epidemic dynamics, which, remarkably, delays the outbreak of disease. We then study the effects of control strategies started at different stages on the prevalence. Both immunization and quarantine strategies indicate that it is not ‘the earlier, the better’ for the implementation of control measures. And the optimal control effect is obtained if control measures can be efficiently implemented in the period of a strong community structure. For the immunization strategy, immunizing the susceptible nodes on susceptible–infected links and immunizing susceptible nodes randomly have similar control effects. However, for the quarantine strategy, quarantining the infected nodes on susceptible–infected links can yield a far better result than quarantining infected nodes randomly. More significantly, the community-based quarantine strategy performs better than the community-based immunization strategy. This study may shed new light on the forecast and the prevention of epidemics among humans. (paper)

  1. Differential Evolution for Many-Particle Adaptive Quantum Metrology

    NARCIS (Netherlands)

    Lovett, N.B.; Crosnier, C.; Perarnau- Llobet, M.; Sanders, B.

    2013-01-01

    We devise powerful algorithms based on differential evolution for adaptive many-particle quantum metrology. Our new approach delivers adaptive quantum metrology policies for feedback control that are orders-of-magnitude more efficient and surpass the few-dozen-particle limitation arising in methods

  2. Adaptation and evolution of drug-resistant Mycobacterium tuberculosis

    NARCIS (Netherlands)

    Bergval, I.L.

    2013-01-01

    Many studies have been conducted on drug resistance and the evolution of Mycobacterium tuberculosis. Notwithstanding, many molecular mechanisms facilitating the emergence, adaptation and spread of drug-resistant tuberculosis have yet to be discovered. This thesis reports studies of the adaptive

  3. Evolution strategy based optimal chiller loading for saving energy

    International Nuclear Information System (INIS)

    Chang, Y.-C.; Lee, C.-Y.; Chen, C.-R.; Chou, C.-J.; Chen, W.-H.; Chen, W.-H.

    2009-01-01

    This study employs evolution strategy (ES) to solve optimal chiller loading (OCL) problem. ES overcomes the flaw that Lagrangian method is not adaptable for solving OCL as the power consumption models or the kW-PLR (partial load ratio) curves include convex functions and concave functions simultaneously. The complicated process of evolution by the genetic algorithm (GA) method for solving OCL can also be simplified by the ES method. This study uses the PLR of chiller as the variable to be solved for the decoupled air conditioning system. After analysis and comparison of the case study, it has been concluded that this method not only solves the problems of Lagrangian method and GA method, but also produces results with high accuracy within a rapid timeframe. It can be perfectly applied to the operation of air conditioning systems

  4. Adaptive Strategies in the Iterated Exchange Problem

    Science.gov (United States)

    Baraov, Arthur

    2011-03-01

    We argue for clear separation of the exchange problem from the exchange paradox to avoid confusion about the subject matter of these two distinct problems. The exchange problem in its current format belongs to the domain of optimal decision making—it doesn't make any sense as a game of competition. But it takes just a tiny modification in the statement of the problem to breathe new life into it and make it a practicable and meaningful game of competition. In this paper, we offer an explanation for paradoxical priors and discuss adaptive strategies for both the house and the player in the restated exchange problem.

  5. Adaptive discrete-ordinates algorithms and strategies

    International Nuclear Information System (INIS)

    Stone, J.C.; Adams, M.L.

    2005-01-01

    We present our latest algorithms and strategies for adaptively refined discrete-ordinates quadrature sets. In our basic strategy, which we apply here in two-dimensional Cartesian geometry, the spatial domain is divided into regions. Each region has its own quadrature set, which is adapted to the region's angular flux. Our algorithms add a 'test' direction to the quadrature set if the angular flux calculated at that direction differs by more than a user-specified tolerance from the angular flux interpolated from other directions. Different algorithms have different prescriptions for the method of interpolation and/or choice of test directions and/or prescriptions for quadrature weights. We discuss three different algorithms of different interpolation orders. We demonstrate through numerical results that each algorithm is capable of generating solutions with negligible angular discretization error. This includes elimination of ray effects. We demonstrate that all of our algorithms achieve a given level of error with far fewer unknowns than does a standard quadrature set applied to an entire problem. To address a potential issue with other algorithms, we present one algorithm that retains exact integration of high-order spherical-harmonics functions, no matter how much local refinement takes place. To address another potential issue, we demonstrate that all of our methods conserve partial currents across interfaces where quadrature sets change. We conclude that our approach is extremely promising for solving the long-standing problem of angular discretization error in multidimensional transport problems. (authors)

  6. Biometeorology - a science supporting adaptation strategies

    Science.gov (United States)

    Matzarakis, A.; Cegnar, T.

    2010-09-01

    Biometeorology as an interdisciplinary science deals with the interactions between atmospheric processes and living organisms (plants, animals and humans). If and in what way weather and climate affect the well-being of all the living creatures? This is the most important question biometeorology is answering. The International Society of Biometeorology (ISB) has built an international forum for the promotion of interdisciplinary collaboration between meteorologists, health professionals, biologists, climatologists, ecologists and other scientists. The Society acts as a community of scientists with similar interests, and fulfills an important role in providing information, expertise and advice for international organizations requiring this assistance. The ISB represents the most comprehensive organization, which brings together people with expertise in these areas. Another specific aim of the ISB is the stimulation of research. Therefore, groups of members are working on several topics organized in commissions for specific targets. The recent five commissions are working in the several fields including climate change issues. Some of examples will be presented, which have been initiated by the members of the ISB and how they can be included as a solid scientific basis to develop efficient adaptation strategies. One such example is a project combining natural and social sciences (in the fields of cooperation processes, tourism analysis and strategy, weather and climate change analysis, information and communication and knowledge transfer) in a transdisciplinary approach that includes players from tourism policy and business and which focuses on the North Sea Coast and the Black Forest. The project "Climate trends and sustainable development of tourism in coastal and mountain range regions was divided into four phases - diagnosis, assessment, strategy/design of solutions, and evaluation - where scientific subprojects and practical partners meet regularly to discuss the

  7. Educational Cognitive Technologies as Human Adaptation Strategies

    Directory of Open Access Journals (Sweden)

    Marja Nesterova

    2017-07-01

    Full Text Available Modernity is characterized by profound changes in all spheres of human life caused by the global transformations on macro and micro levels of social reality. These changes allow us to speak about the present as the era of civilizational transition in the mode of uncertainty. Therefore, this situation demands qualitative transformations of human adaptive strategies and educational technologies accordingly. The dominant role in the dynamics of pedagogics and andragogy’s landscape belongs to transformative learning. The transformative learning theory is considered as the relevant approach to education of the individual, which is able to become an autonomous communicative actor of the social complexity. The article considers the cognitive technologies of social cohesion development and perspectives of their implementation in the educational dimension. In addition to implementing the principles of inclusion, equity in education, an important factor for improving social cohesion, stability and unity of society is the development of cognitive educational technologies. The key factors and foundations for the cognitive educational technologies are transversal competencies. They create the conditions for civil, public dialogue, non-violent type of communication. These “21st century skills” are extremely important for better human adaptation. One of the aspects and roots of social adaptation is social cohesion. Mutual determinations and connections between social cohesion development and transversal competences have been shown. The perspective direction of further researches is to find a methodological base for the further development of cognitive education technologies and platform for realization of innovative services for educational programs. New educational paradigm offers the concept of human adaptation as cognitive effectiveness and how to reach it through educational technologies. The article includes topics of creative thinking, teambuilding

  8. Adaptive laboratory evolution – principles and applications for biotechnology

    Science.gov (United States)

    2013-01-01

    Adaptive laboratory evolution is a frequent method in biological studies to gain insights into the basic mechanisms of molecular evolution and adaptive changes that accumulate in microbial populations during long term selection under specified growth conditions. Although regularly performed for more than 25 years, the advent of transcript and cheap next-generation sequencing technologies has resulted in many recent studies, which successfully applied this technique in order to engineer microbial cells for biotechnological applications. Adaptive laboratory evolution has some major benefits as compared with classical genetic engineering but also some inherent limitations. However, recent studies show how some of the limitations may be overcome in order to successfully incorporate adaptive laboratory evolution in microbial cell factory design. Over the last two decades important insights into nutrient and stress metabolism of relevant model species were acquired, whereas some other aspects such as niche-specific differences of non-conventional cell factories are not completely understood. Altogether the current status and its future perspectives highlight the importance and potential of adaptive laboratory evolution as approach in biotechnological engineering. PMID:23815749

  9. Convergent evolution and adaptation of Pseudomonas aeruginosa within patients with cystic fibrosis.

    Science.gov (United States)

    Marvig, Rasmus Lykke; Sommer, Lea Mette; Molin, Søren; Johansen, Helle Krogh

    2015-01-01

    Little is known about how within-host evolution compares between genotypically different strains of the same pathogenic species. We sequenced the whole genomes of 474 longitudinally collected clinical isolates of Pseudomonas aeruginosa sampled from 34 children and young individuals with cystic fibrosis. Our analysis of 36 P. aeruginosa lineages identified convergent molecular evolution in 52 genes. This list of genes suggests a role in host adaptation for remodeling of regulatory networks and central metabolism, acquisition of antibiotic resistance and loss of extracellular virulence factors. Furthermore, we find an ordered succession of mutations in key regulatory networks. Accordingly, mutations in downstream transcriptional regulators were contingent upon mutations in upstream regulators, suggesting that remodeling of regulatory networks might be important in adaptation. The characterization of genes involved in host adaptation may help in predicting bacterial evolution in patients with cystic fibrosis and in the design of future intervention strategies.

  10. Evolution Strategies in the Multipoint Connections Routing

    Directory of Open Access Journals (Sweden)

    L. Krulikovska

    2010-09-01

    Full Text Available Routing of multipoint connections plays an important role in final cost and quality of a found connection. New algorithms with better results are still searched. In this paper, a possibility of using the evolution strategies (ES for routing is presented. Quality of found connection is evaluated from the view of final cost and time spent on a searching procedure. First, parametrical analysis of results of the ES are discussed and compared with the Prim’s algorithm, which was chosen as a representative of the deterministic routing algorithms. Second, ways for improving the ES are suggested and implemented. The obtained results are reviewed. The main improvements are specified and discussed in conclusion.

  11. Adaptive processes drive ecomorphological convergent evolution in antwrens (Thamnophilidae).

    Science.gov (United States)

    Bravo, Gustavo A; Remsen, J V; Brumfield, Robb T

    2014-10-01

    Phylogenetic niche conservatism (PNC) and convergence are contrasting evolutionary patterns that describe phenotypic similarity across independent lineages. Assessing whether and how adaptive processes give origin to these patterns represent a fundamental step toward understanding phenotypic evolution. Phylogenetic model-based approaches offer the opportunity not only to distinguish between PNC and convergence, but also to determine the extent that adaptive processes explain phenotypic similarity. The Myrmotherula complex in the Neotropical family Thamnophilidae is a polyphyletic group of sexually dimorphic small insectivorous forest birds that are relatively homogeneous in size and shape. Here, we integrate a comprehensive species-level molecular phylogeny of the Myrmotherula complex with morphometric and ecological data within a comparative framework to test whether phenotypic similarity is described by a pattern of PNC or convergence, and to identify evolutionary mechanisms underlying body size and shape evolution. We show that antwrens in the Myrmotherula complex represent distantly related clades that exhibit adaptive convergent evolution in body size and divergent evolution in body shape. Phenotypic similarity in the group is primarily driven by their tendency to converge toward smaller body sizes. Differences in body size and shape across lineages are associated to ecological and behavioral factors. © 2014 The Author(s). Evolution © 2014 The Society for the Study of Evolution.

  12. Towards a national adaptation strategy in view of climate changes

    Directory of Open Access Journals (Sweden)

    E. DOUKAKIS

    2004-06-01

    • The general national adaptation principles. The presentation analyses all the above concepts and proposes specific guidelines to formulate a Greek National Adaptation Strategy to mitigate the impacts of anthropogenic climate changes.

  13. Adaptive Evolution of Phosphorus Metabolism in Prochlorococcus

    DEFF Research Database (Denmark)

    Casey, John R; Mardinoglu, Adil; Nielsen, Jens

    2016-01-01

    Inorganic phosphorus is scarce in the eastern Mediterranean Sea, where the high-light-adapted ecotype HLI of the marine picocyanobacterium Prochlorococcus marinus thrives. Physiological and regulatory control of phosphorus acquisition and partitioning has been observed in HLI both in culture...... and in the field; however, the optimization of phosphorus metabolism and associated gains for its phosphorus-limited-growth (PLG) phenotype have not been studied. Here, we reconstructed a genome-scale metabolic network of the HLI axenic strain MED4 (iJC568), consisting of 568 metabolic genes in relation to 794...... through drastic depletion of phosphorus-containing biomass components but also through network-wide reductions in phosphate-reaction participation and the loss of a key enzyme, succinate dehydrogenase. These alterations occur despite the stringency of having relatively few pathway redundancies...

  14. An adaptive ES with a ranking based constraint handling strategy

    Directory of Open Access Journals (Sweden)

    Kusakci Ali Osman

    2014-01-01

    Full Text Available To solve a constrained optimization problem, equality constraints can be used to eliminate a problem variable. If it is not feasible, the relations imposed implicitly by the constraints can still be exploited. Most conventional constraint handling methods in Evolutionary Algorithms (EAs do not consider the correlations between problem variables imposed by the constraints. This paper relies on the idea that a proper search operator, which captures mentioned implicit correlations, can improve performance of evolutionary constrained optimization algorithms. To realize this, an Evolution Strategy (ES along with a simplified Covariance Matrix Adaptation (CMA based mutation operator is used with a ranking based constraint-handling method. The proposed algorithm is tested on 13 benchmark problems as well as on a real life design problem. The outperformance of the algorithm is significant when compared with conventional ES-based methods.

  15. Identification of genes that have undergone adaptive evolution in ...

    African Journals Online (AJOL)

    Cassava (Manihot esculenta) is a vital food security crop and staple in Africa, yet cassava brown streak disease (CBSD) and cassava mosaic disease result in substantial yield losses. The aim of this study was to identify genes that have undergone positive selection during adaptive evolution, from CBSD resistant, tolerant ...

  16. Adaptive evolution and effective population size in wild house mice

    Czech Academy of Sciences Publication Activity Database

    Phifer-Rixey, M.; Bonhomme, F.; Boursot, P.; Churchill, G. A.; Piálek, Jaroslav; Tucker, P.; Nachman, M.

    2012-01-01

    Roč. 29, č. 10 (2012), s. 2949-2955 ISSN 0737-4038 R&D Projects: GA ČR GA206/08/0640 Institutional support: RVO:68081766 Keywords : substitution * adaptation * evolution * effective population size * house mouse Subject RIV: EG - Zoology Impact factor: 10.353, year: 2012

  17. The rule of declining adaptability in microbial evolution experiments

    Science.gov (United States)

    Couce, Alejandro; Tenaillon, Olivier A.

    2015-01-01

    One of the most recurrent observations after two decades of microbial evolution experiments regards the dynamics of fitness change. In a given environment, low-fitness genotypes are recurrently observed to adapt faster than their more fit counterparts. Since adaptation is the main macroscopic outcome of Darwinian evolution, studying its patterns of change could potentially provide insight into key issues of evolutionary theory, from fixation dynamics to the genetic architecture of organisms. Here, we re-analyze several published datasets from experimental evolution with microbes and show that, despite large differences in the origin of the data, a pattern of inverse dependence of adaptability with fitness clearly emerges. In quantitative terms, it is remarkable to observe little if any degree of idiosyncrasy across systems as diverse as virus, bacteria and yeast. The universality of this phenomenon suggests that its emergence might be understood from general principles, giving rise to the exciting prospect that evolution might be statistically predictable at the macroscopic level. We discuss these possibilities in the light of the various theories of adaptation that have been proposed and delineate future directions of research. PMID:25815007

  18. Adaptive evolution of plastron shape in emydine turtles.

    Science.gov (United States)

    Angielczyk, Kenneth D; Feldman, Chris R; Miller, Gretchen R

    2011-02-01

    Morphology reflects ecological pressures, phylogeny, and genetic and biophysical constraints. Disentangling their influence is fundamental to understanding selection and trait evolution. Here, we assess the contributions of function, phylogeny, and habitat to patterns of plastron (ventral shell) shape variation in emydine turtles. We quantify shape variation using geometric morphometrics, and determine the influence of several variables on shape using path analysis. Factors influencing plastron shape variation are similar between emydine turtles and the more inclusive Testudinoidea. We evaluate the fit of various evolutionary models to the shape data to investigate the selective landscape responsible for the observed morphological patterns. The presence of a hinge on the plastron accounts for most morphological variance, but phylogeny and habitat also correlate with shape. The distribution of shape variance across emydine phylogeny is most consistent with an evolutionary model containing two adaptive zones--one for turtles with kinetic plastra, and one for turtles with rigid plastra. Models with more complex adaptive landscapes often fit the data only as well as the null model (purely stochastic evolution). The adaptive landscape of plastron shape in Emydinae may be relatively simple because plastral kinesis imposes overriding mechanical constraints on the evolution of form. © 2010 The Author(s). Evolution© 2010 The Society for the Study of Evolution.

  19. Camelid genomes reveal evolution and adaptation to desert environments.

    Science.gov (United States)

    Wu, Huiguang; Guang, Xuanmin; Al-Fageeh, Mohamed B; Cao, Junwei; Pan, Shengkai; Zhou, Huanmin; Zhang, Li; Abutarboush, Mohammed H; Xing, Yanping; Xie, Zhiyuan; Alshanqeeti, Ali S; Zhang, Yanru; Yao, Qiulin; Al-Shomrani, Badr M; Zhang, Dong; Li, Jiang; Manee, Manee M; Yang, Zili; Yang, Linfeng; Liu, Yiyi; Zhang, Jilin; Altammami, Musaad A; Wang, Shenyuan; Yu, Lili; Zhang, Wenbin; Liu, Sanyang; Ba, La; Liu, Chunxia; Yang, Xukui; Meng, Fanhua; Wang, Shaowei; Li, Lu; Li, Erli; Li, Xueqiong; Wu, Kaifeng; Zhang, Shu; Wang, Junyi; Yin, Ye; Yang, Huanming; Al-Swailem, Abdulaziz M; Wang, Jun

    2014-10-21

    Bactrian camel (Camelus bactrianus), dromedary (Camelus dromedarius) and alpaca (Vicugna pacos) are economically important livestock. Although the Bactrian camel and dromedary are large, typically arid-desert-adapted mammals, alpacas are adapted to plateaus. Here we present high-quality genome sequences of these three species. Our analysis reveals the demographic history of these species since the Tortonian Stage of the Miocene and uncovers a striking correlation between large fluctuations in population size and geological time boundaries. Comparative genomic analysis reveals complex features related to desert adaptations, including fat and water metabolism, stress responses to heat, aridity, intense ultraviolet radiation and choking dust. Transcriptomic analysis of Bactrian camels further reveals unique osmoregulation, osmoprotection and compensatory mechanisms for water reservation underpinned by high blood glucose levels. We hypothesize that these physiological mechanisms represent kidney evolutionary adaptations to the desert environment. This study advances our understanding of camelid evolution and the adaptation of camels to arid-desert environments.

  20. Command Resiliency: An Adaptive Response Strategy for Complex Incidents

    National Research Council Canada - National Science Library

    Pfeifer, Joseph W

    2005-01-01

    .... Unless organizations develop a resilient response strategy that can adapt organizational and operational elements to respond to new terrorist incidents, they will find themselves with the same...

  1. The adaptive evolution of the mammalian mitochondrial genome

    Directory of Open Access Journals (Sweden)

    O'Brien Stephen J

    2008-03-01

    Full Text Available Abstract Background The mitochondria produce up to 95% of a eukaryotic cell's energy through oxidative phosphorylation. The proteins involved in this vital process are under high functional constraints. However, metabolic requirements vary across species, potentially modifying selective pressures. We evaluate the adaptive evolution of 12 protein-coding mitochondrial genes in 41 placental mammalian species by assessing amino acid sequence variation and exploring the functional implications of observed variation in secondary and tertiary protein structures. Results Wide variation in the properties of amino acids were observed at functionally important regions of cytochrome b in species with more-specialized metabolic requirements (such as adaptation to low energy diet or large body size, such as in elephant, dugong, sloth, and pangolin, and adaptation to unusual oxygen requirements, for example diving in cetaceans, flying in bats, and living at high altitudes in alpacas. Signatures of adaptive variation in the NADH dehydrogenase complex were restricted to the loop regions of the transmembrane units which likely function as protons pumps. Evidence of adaptive variation in the cytochrome c oxidase complex was observed mostly at the interface between the mitochondrial and nuclear-encoded subunits, perhaps evidence of co-evolution. The ATP8 subunit, which has an important role in the assembly of F0, exhibited the highest signal of adaptive variation. ATP6, which has an essential role in rotor performance, showed a high adaptive variation in predicted loop areas. Conclusion Our study provides insight into the adaptive evolution of the mtDNA genome in mammals and its implications for the molecular mechanism of oxidative phosphorylation. We present a framework for future experimental characterization of the impact of specific mutations in the function, physiology, and interactions of the mtDNA encoded proteins involved in oxidative phosphorylation.

  2. Quantifying adaptive evolution in the Drosophila immune system.

    Directory of Open Access Journals (Sweden)

    Darren J Obbard

    2009-10-01

    Full Text Available It is estimated that a large proportion of amino acid substitutions in Drosophila have been fixed by natural selection, and as organisms are faced with an ever-changing array of pathogens and parasites to which they must adapt, we have investigated the role of parasite-mediated selection as a likely cause. To quantify the effect, and to identify which genes and pathways are most likely to be involved in the host-parasite arms race, we have re-sequenced population samples of 136 immunity and 287 position-matched non-immunity genes in two species of Drosophila. Using these data, and a new extension of the McDonald-Kreitman approach, we estimate that natural selection fixes advantageous amino acid changes in immunity genes at nearly double the rate of other genes. We find the rate of adaptive evolution in immunity genes is also more variable than other genes, with a small subset of immune genes evolving under intense selection. These genes, which are likely to represent hotspots of host-parasite coevolution, tend to share similar functions or belong to the same pathways, such as the antiviral RNAi pathway and the IMD signalling pathway. These patterns appear to be general features of immune system evolution in both species, as rates of adaptive evolution are correlated between the D. melanogaster and D. simulans lineages. In summary, our data provide quantitative estimates of the elevated rate of adaptive evolution in immune system genes relative to the rest of the genome, and they suggest that adaptation to parasites is an important force driving molecular evolution.

  3. A holistic strategy for adaptive land management

    Science.gov (United States)

    Adaptive management is widely applied to natural resources management. Adaptive management can be generally defined as an iterative decision-making process that incorporates formulation of management objectives, actions designed to address these objectives, monitoring of results, and repeated adapta...

  4. Adaptation strategies and approaches: Chapter 2

    Science.gov (United States)

    Patricia Butler; Chris Swanston; Maria Janowiak; Linda Parker; Matt St. Pierre; Leslie. Brandt

    2012-01-01

    A wealth of information is available on climate change adaptation, but much of it is very broad and of limited use at the finer spatial scales most relevant to land managers. This chapter contains a "menu" of adaptation actions and provides land managers in northern Wisconsin with a range of options to help forest ecosystems adapt to climate change impacts....

  5. Mobilizable genomic islands, different strategies for the dissemination of multidrug resistance and other adaptive traits

    NARCIS (Netherlands)

    Carraro, N.; Rivard, N.; Burrus, V.; Ceccarelli, Daniela

    2017-01-01

    Mobile genetic elements are near ubiquitous DNA segments that revealed a surprising variety of strategies for their propagation among prokaryotes and between eukaryotes. In bacteria, conjugative elements were shown to be key drivers of evolution and adaptation by efficiently disseminating genes

  6. Adaptive evolution of conserved noncoding elements in mammals.

    Directory of Open Access Journals (Sweden)

    Su Yeon Kim

    2007-09-01

    Full Text Available Conserved noncoding elements (CNCs are an abundant feature of vertebrate genomes. Some CNCs have been shown to act as cis-regulatory modules, but the function of most CNCs remains unclear. To study the evolution of CNCs, we have developed a statistical method called the "shared rates test" to identify CNCs that show significant variation in substitution rates across branches of a phylogenetic tree. We report an application of this method to alignments of 98,910 CNCs from the human, chimpanzee, dog, mouse, and rat genomes. We find that approximately 68% of CNCs evolve according to a null model where, for each CNC, a single parameter models the level of constraint acting throughout the phylogeny linking these five species. The remaining approximately 32% of CNCs show departures from the basic model including speed-ups and slow-downs on particular branches and occasionally multiple rate changes on different branches. We find that a subset of the significant CNCs have evolved significantly faster than the local neutral rate on a particular branch, providing strong evidence for adaptive evolution in these CNCs. The distribution of these signals on the phylogeny suggests that adaptive evolution of CNCs occurs in occasional short bursts of evolution. Our analyses suggest a large set of promising targets for future functional studies of adaptation.

  7. Assessing climate change impacts and adaptation strategies for ...

    African Journals Online (AJOL)

    Assessing climate change impacts and adaptation strategies for smallholder agricultural systems in Uganda. ... from encroaching on swamps, which is one of the reported adaptation strategies to climate related stresses. Improving productivity of important crops (bananas for southwest, and sweet potatoes and bananas

  8. Adaptation Strategies to Climate Change by Food Crop Farmers in ...

    African Journals Online (AJOL)

    ... constraints to farmers adaptation strategies. Inputs supply to the local farmers should also come with government subsidy. This will go a long way in alleviating the sufferings of the farmers, as regards inadequate supply and delivery of agricultural inputs. Key words: Adaptation, Strategies, Climate, Change, Food, Crop,

  9. Growing assisted migration: Synthesis of a climate change adaptation strategy

    Science.gov (United States)

    Mary I. Williams; R. Kasten Dumroese

    2013-01-01

    Assisted migration may be necessary as a climate change adaptation strategy for native plant species that are less adaptive or mobile. Moving plants has been practiced a long time in human history, but movement of species in response to climate change is a new context. First proposed in 1985, assisted migration has gained attention since 2007 as a strategy to prevent...

  10. Adapting MCH strategies for the nineties.

    Science.gov (United States)

    Abel, R

    1994-01-01

    Brief overview was given for strategies in maternal and child health (MCH) in India that were used in the 1980s and adapted for the 1990s in the following areas: perinatal outcomes, empowerment of women, immunization, oral rehydration, adolescent girls, anthropometric measurement, health education, management, and coordination with nongovernmental organizations (NGOs). In order to assure a healthy baby weighing 2.5 kg, monitoring of maternal health is occurring. Iron and folic acid and tetanus toxoid vaccine are provided to pregnant mothers, and fetal growth is monitored. Training of traditional birth attendants and multipurpose health workers will contribute to clean deliveries and referral of complicated pregnancies. During the 1990s, women's health in addition to maternal health has received attention. The empowerment of women to care for themselves, to learn how to mix oral rehydration packets (ORS) at home, and to receive the knowledge and skills were deemed more important than the 1980s focus on the delivery system and inputs of MCH. An excellent cold chain for delivery of vaccines has been put in place, which provides the vehicle for the 1990s to maintain high vaccine coverage. The emphasis on oral rehydration in the 1990s will be on teaching mothers about the importance of ORS treatment of diarrhea. During the 1990s, educating the adolescent girl before she becomes married and pregnant will be the focus. Greater emphasis will be placed on stunting or height for age measurements, as a measure of long term nutritional change; age weight for height for measurement of wasting; and maternal nutritional monitoring of arm circumference. Sustained health education, more media exposure to disease conditions and treatment, and social marketing in health will be better coordinated and more cost effective. Accountability for manpower, materials, and money will be in place within management. Management will focus on motivation and training, and other, newer management

  11. Pollinator adaptation and the evolution of floral nectar sugar composition.

    Science.gov (United States)

    Abrahamczyk, S; Kessler, M; Hanley, D; Karger, D N; Müller, M P J; Knauer, A C; Keller, F; Schwerdtfeger, M; Humphreys, A M

    2017-01-01

    A long-standing debate concerns whether nectar sugar composition evolves as an adaptation to pollinator dietary requirements or whether it is 'phylogenetically constrained'. Here, we use a modelling approach to evaluate the hypothesis that nectar sucrose proportion (NSP) is an adaptation to pollinators. We analyse ~ 2100 species of asterids, spanning several plant families and pollinator groups (PGs), and show that the hypothesis of adaptation cannot be rejected: NSP evolves towards two optimal values, high NSP for specialist-pollinated and low NSP for generalist-pollinated plants. However, the inferred adaptive process is weak, suggesting that adaptation to PG only provides a partial explanation for how nectar evolves. Additional factors are therefore needed to fully explain nectar evolution, and we suggest that future studies might incorporate floral shape and size and the abiotic environment into the analytical framework. Further, we show that NSP and PG evolution are correlated - in a manner dictated by pollinator behaviour. This contrasts with the view that a plant necessarily has to adapt its nectar composition to ensure pollination but rather suggests that pollinators adapt their foraging behaviour or dietary requirements to the nectar sugar composition presented by the plants. Finally, we document unexpectedly sucrose-poor nectar in some specialized nectarivorous bird-pollinated plants from the Old World, which might represent an overlooked form of pollinator deception. Thus, our broad study provides several new insights into how nectar evolves and we conclude by discussing why maintaining the conceptual dichotomy between adaptation and constraint might be unhelpful for advancing this field. © 2016 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2016 European Society For Evolutionary Biology.

  12. A holistic strategy for adaptive land management

    Science.gov (United States)

    Herrick, Jeffrey E.; Duniway, Michael C.; Pyke, David A.; Bestelmeyer, Brandon T.; Wills, Skye A.; Brown, Joel R.; Karl, Jason W.; Havstad, Kris M.

    2012-01-01

    Adaptive management is widely applied to natural resources management (Holling 1973; Walters and Holling 1990). Adaptive management can be generally defined as an iterative decision-making process that incorporates formulation of management objectives, actions designed to address these objectives, monitoring of results, and repeated adaptation of management until desired results are achieved (Brown and MacLeod 1996; Savory and Butterfield 1999). However, adaptive management is often criticized because very few projects ever complete more than one cycle, resulting in little adaptation and little knowledge gain (Lee 1999; Walters 2007). One significant criticism is that adaptive management is often used as a justification for undertaking actions with uncertain outcomes or as a surrogate for the development of specific, measurable indicators and monitoring programs (Lee 1999; Ruhl 2007).

  13. A New Adaptive Checkpointing Strategy for Mobile Computing

    Institute of Scientific and Technical Information of China (English)

    MENChaoguang; ZUODecheng; YANGXiaozong

    2005-01-01

    Adaptive checkpointing strategy is an efficient recovery scheme, which is suitable for mobile computing system. However, all existing adaptive checkpointing schemes are not correct to recover system when failure occurs in some special period. In this paper, the issues that will lead to system inconsistency are first discussed and then a new adaptive strategy that can recover system to correct consistent state is proposed. Our algorithm improves system recovery performance because only failure process needs rollback through logging.

  14. ESA Earth Observation Ground Segment Evolution Strategy

    Science.gov (United States)

    Benveniste, J.; Albani, M.; Laur, H.

    2016-12-01

    One of the key elements driving the evolution of EO Ground Segments, in particular in Europe, has been to enable the creation of added value from EO data and products. This requires the ability to constantly adapt and improve the service to a user base expanding far beyond the `traditional' EO user community of remote sensing specialists. Citizen scientists, the general public, media and educational actors form another user group that is expected to grow. Technological advances, Open Data policies, including those implemented by ESA and the EU, as well as an increasing number of satellites in operations (e.g. Copernicus Sentinels) have led to an enormous increase in available data volumes. At the same time, even with modern network and data handling services, fewer users can afford to bulk-download and consider all potentially relevant data and associated knowledge. The "EO Innovation Europe" concept is being implemented in Europe in coordination between the European Commission, ESA and other European Space Agencies, and industry. This concept is encapsulated in the main ideas of "Bringing the User to the Data" and "Connecting the Users" to complement the traditional one-to-one "data delivery" approach of the past. Both ideas are aiming to better "empower the users" and to create a "sustainable system of interconnected EO Exploitation Platforms", with the objective to enable large scale exploitation of European EO data assets for stimulating innovation and to maximize their impact. These interoperable/interconnected platforms are virtual environments in which the users - individually or collaboratively - have access to the required data sources and processing tools, as opposed to downloading and handling the data `at home'. EO-Innovation Europe has been structured around three elements: an enabling element (acting as a back office), a stimulating element and an outreach element (acting as a front office). Within the enabling element, a "mutualisation" of efforts

  15. Increased tolerance towards serine obtained by adaptive laboratory evolution

    DEFF Research Database (Denmark)

    Mundhada, Hemanshu; Seoane, Jose Miguel; Koza, Anna

    2014-01-01

    The amino acid serine has previously been identified as one of the top 30 candidates of value added chemicals, making the production of serine from glucose attractive. Production of serine have previously been attempted in E. coli and C. glutamicum, however, titers sufficient for commercial...... by glyA), the conversion of serine to pyruvate (encoded by sdaA, sdaB and tdcG) was also deleted. As expected, the resulting strain turned out to be susceptible to even low concentrations of serine in the media. In order to improve the tolerance of the strain towards serine, adaptive laboratory evolution....... During the evolution experiment, the serine tolerance was increased substantially. Genome re-sequencing was subsequently used to analyze the genotype of a number of selected strains. These results reveal insights towards the adaptation process as well as the mechanism of serine tolerance....

  16. Europe adapts to climate change: Comparing National Adaptation Strategies

    DEFF Research Database (Denmark)

    Biesbroek, G. Robbert; Swart, Rob J.; Carter, Timothy R.

    2010-01-01

    For the last two decades, European climate policy has focused almost exclusively on mitigation of climate change. It was only well after the turn of the century, with impacts of climate change increasingly being observed, that adaptation was added to the policy agenda and EU Member States started...

  17. Evolution and Adaptation in Pseudomonas aeruginosa Biofilms Driven by Mismatch Repair System-Deficient Mutators

    DEFF Research Database (Denmark)

    Luján, Adela M.; Maciá, María D.; Yang, Liang

    2011-01-01

    , which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS)], play important roles in P. aeruginosa chronic...... infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition...... diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution...

  18. An Adaptive Laboratory Evolution Method to Accelerate Autotrophic Metabolism

    DEFF Research Database (Denmark)

    Zhang, Tian; Tremblay, Pier-Luc

    2018-01-01

    Adaptive laboratory evolution (ALE) is an approach enabling the development of novel characteristics in microbial strains via the application of a constant selection pressure. This method is also an efficient tool to acquire insights on molecular mechanisms responsible for specific phenotypes. ALE...... autotrophically and reducing CO2 into acetate more efficiently. Strains developed via this ALE method were also used to gain knowledge on the autotrophic metabolism of S. ovata as well as other acetogenic bacteria....

  19. Adaptive evolution of facial colour patterns in Neotropical primates

    OpenAIRE

    Santana, Sharlene E.; Lynch Alfaro, Jessica; Alfaro, Michael E.

    2012-01-01

    The rich diversity of primate faces has interested naturalists for over a century. Researchers have long proposed that social behaviours have shaped the evolution of primate facial diversity. However, the primate face constitutes a unique structure where the diverse and potentially competing functions of communication, ecology and physiology intersect, and the major determinants of facial diversity remain poorly understood. Here, we provide the first evidence for an adaptive role of facial co...

  20. Strategy correlations and timing of adaptation in Minority Games

    OpenAIRE

    Galla, Tobias; Sherrington, David

    2005-01-01

    We study the role of strategy correlations and timing of adaptation for the dynamics of Minority Games, both simulationally and analytically. Using the exact generating functional approach a la De Dominicis we compute the phase diagram and the behaviour of batch and on-line games with correlated strategies, complementing exisiting replica studies of their statics. It is shown that the timing of adaptation can be relevant; while conventional games with uncorrelated strategies are nearly insens...

  1. Experimental evolution and the dynamics of adaptation and genome evolution in microbial populations.

    Science.gov (United States)

    Lenski, Richard E

    2017-10-01

    Evolution is an on-going process, and it can be studied experimentally in organisms with rapid generations. My team has maintained 12 populations of Escherichia coli in a simple laboratory environment for >25 years and 60 000 generations. We have quantified the dynamics of adaptation by natural selection, seen some of the populations diverge into stably coexisting ecotypes, described changes in the bacteria's mutation rate, observed the new ability to exploit a previously untapped carbon source, characterized the dynamics of genome evolution and used parallel evolution to identify the genetic targets of selection. I discuss what the future might hold for this particular experiment, briefly highlight some other microbial evolution experiments and suggest how the fields of experimental evolution and microbial ecology might intersect going forward.

  2. Sex speeds adaptation by altering the dynamics of molecular evolution.

    Science.gov (United States)

    McDonald, Michael J; Rice, Daniel P; Desai, Michael M

    2016-03-10

    Sex and recombination are pervasive throughout nature despite their substantial costs. Understanding the evolutionary forces that maintain these phenomena is a central challenge in biology. One longstanding hypothesis argues that sex is beneficial because recombination speeds adaptation. Theory has proposed several distinct population genetic mechanisms that could underlie this advantage. For example, sex can promote the fixation of beneficial mutations either by alleviating interference competition (the Fisher-Muller effect) or by separating them from deleterious load (the ruby in the rubbish effect). Previous experiments confirm that sex can increase the rate of adaptation, but these studies did not observe the evolutionary dynamics that drive this effect at the genomic level. Here we present the first, to our knowledge, comparison between the sequence-level dynamics of adaptation in experimental sexual and asexual Saccharomyces cerevisiae populations, which allows us to identify the specific mechanisms by which sex speeds adaptation. We find that sex alters the molecular signatures of evolution by changing the spectrum of mutations that fix, and confirm theoretical predictions that it does so by alleviating clonal interference. We also show that substantially deleterious mutations hitchhike to fixation in adapting asexual populations. In contrast, recombination prevents such mutations from fixing. Our results demonstrate that sex both speeds adaptation and alters its molecular signature by allowing natural selection to more efficiently sort beneficial from deleterious mutations.

  3. Evolution of strategies for modern rechargeable batteries.

    Science.gov (United States)

    Goodenough, John B

    2013-05-21

    This Account provides perspective on the evolution of the rechargeable battery and summarizes innovations in the development of these devices. Initially, I describe the components of a conventional rechargeable battery along with the engineering parameters that define the figures of merit for a single cell. In 1967, researchers discovered fast Na(+) conduction at 300 K in Na β,β''-alumina. Since then battery technology has evolved from a strongly acidic or alkaline aqueous electrolyte with protons as the working ion to an organic liquid-carbonate electrolyte with Li(+) as the working ion in a Li-ion battery. The invention of the sodium-sulfur and Zebra batteries stimulated consideration of framework structures as crystalline hosts for mobile guest alkali ions, and the jump in oil prices in the early 1970s prompted researchers to consider alternative room-temperature batteries with aprotic liquid electrolytes. With the existence of Li primary cells and ongoing research on the chemistry of reversible Li intercalation into layered chalcogenides, industry invested in the production of a Li/TiS2 rechargeable cell. However, on repeated recharge, dendrites grew across the electrolyte from the anode to the cathode, leading to dangerous short-circuits in the cell in the presence of the flammable organic liquid electrolyte. Because lowering the voltage of the anode would prevent cells with layered-chalcogenide cathodes from competing with cells that had an aqueous electrolyte, researchers quickly abandoned this effort. However, once it was realized that an oxide cathode could offer a larger voltage versus lithium, researchers considered the extraction of Li from the layered LiMO2 oxides with M = Co or Ni. These oxide cathodes were fabricated in a discharged state, and battery manufacturers could not conceive of assembling a cell with a discharged cathode. Meanwhile, exploration of Li intercalation into graphite showed that reversible Li insertion into carbon occurred

  4. Extensive X-linked adaptive evolution in central chimpanzees

    DEFF Research Database (Denmark)

    Hvilsom, Christina; Qian, Yu; Bataillon, Thomas

    2012-01-01

    on the dominance of beneficial (adaptive) and deleterious mutations. Here we capture and sequence the complete exomes of 12 chimpanzees and present the largest set of protein-coding polymorphism to date. We report extensive adaptive evolution specifically targeting the X chromosome of chimpanzees with as much...... to humans, we find that purifying selection is stronger on the X chromosome than on the autosomes in chimpanzees. We therefore conclude that most adaptive mutations are recessive. We also document dramatically reduced synonymous diversity in the chimpanzee X chromosome relative to autosomes and stronger...... purifying selection than for the human X chromosome. If similar processes were operating in the human-chimpanzee ancestor as in central chimpanzees today, our results therefore provide an explanation for the much-discussed reduction in the human-chimpanzee divergence at the X chromosome....

  5. climate changes and farmers' endogenous adaptation strategies

    African Journals Online (AJOL)

    Prof. Adipala Ekwamu

    20, Issue Supplement s2, pp. 193 - 202 ... SOCIO ECONOMIC ANALYSIS OF THE DYNAMIC USE OF AGRICULTURAL LANDS IN. CENTRAL ... adaptation actually occurs in economic and social ... land fertility is generally known as bad now.

  6. Adaptive evolution of cooperation through Darwinian dynamics in Public Goods games.

    Science.gov (United States)

    Deng, Kuiying; Chu, Tianguang

    2011-01-01

    The linear or threshold Public Goods game (PGG) is extensively accepted as a paradigmatic model to approach the evolution of cooperation in social dilemmas. Here we explore the significant effect of nonlinearity of the structures of public goods on the evolution of cooperation within the well-mixed population by adopting Darwinian dynamics, which simultaneously consider the evolution of populations and strategies on a continuous adaptive landscape, and extend the concept of evolutionarily stable strategy (ESS) as a coalition of strategies that is both convergent-stable and resistant to invasion. Results show (i) that in the linear PGG contributing nothing is an ESS, which contradicts experimental data, (ii) that in the threshold PGG contributing the threshold value is a fragile ESS, which cannot resist the invasion of contributing nothing, and (iii) that there exists a robust ESS of contributing more than half in the sigmoid PGG if the return rate is relatively high. This work reveals the significant effect of the nonlinearity of the structures of public goods on the evolution of cooperation, and suggests that, compared with the linear or threshold PGG, the sigmoid PGG might be a more proper model for the evolution of cooperation within the well-mixed population.

  7. A Self-Adaptive Evolutionary Approach to the Evolution of Aesthetic Maps for a RTS Game

    OpenAIRE

    Lara-Cabrera, Raúl; Cotta, Carlos; Fernández-Leiva, Antonio J.

    2014-01-01

    Procedural content generation (PCG) is a research eld on the rise,with numerous papers devoted to this topic. This paper presents a PCG method based on a self-adaptive evolution strategy for the automatic generation of maps for the real-time strategy (RTS) game PlanetWars. These maps are generated in order to ful ll the aesthetic preferences of the user, as implied by her assessment of a collection of maps used as training set. A topological approach is used for the characterization of th...

  8. Effects of adaptive degrees of trust on coevolution of quantum strategies on scale-free networks

    Science.gov (United States)

    Li, Qiang; Chen, Minyou; Perc, Matjaž; Iqbal, Azhar; Abbott, Derek

    2013-10-01

    We study the impact of adaptive degrees of trust on the evolution of cooperation in the quantum prisoner's dilemma game. In addition to the strategies, links between players are also subject to evolution. Starting with a scale-free interaction network, players adjust trust towards their neighbors based on received payoffs. The latter governs the strategy adoption process, while trust governs the rewiring of links. As soon as the degree of trust towards a neighbor drops to zero, the link is rewired to another randomly chosen player within the network. We find that for small temptations to defect cooperators always dominate, while for intermediate and strong temptations a single quantum strategy is able to outperform all other strategies. In general, reciprocal trust remains within close relationships and favors the dominance of a single strategy. Due to coevolution, the power-law degree distributions transform to Poisson distributions.

  9. Adaptive strategies for cumulative cultural learning.

    Science.gov (United States)

    Ehn, Micael; Laland, Kevin

    2012-05-21

    The demographic and ecological success of our species is frequently attributed to our capacity for cumulative culture. However, it is not yet known how humans combine social and asocial learning to generate effective strategies for learning in a cumulative cultural context. Here we explore how cumulative culture influences the relative merits of various pure and conditional learning strategies, including pure asocial and social learning, critical social learning, conditional social learning and individual refiner strategies. We replicate the Rogers' paradox in the cumulative setting. However, our analysis suggests that strategies that resolved Rogers' paradox in a non-cumulative setting may not necessarily evolve in a cumulative setting, thus different strategies will optimize cumulative and non-cumulative cultural learning. Copyright © 2012 Elsevier Ltd. All rights reserved.

  10. Gene expression and adaptive noncoding changes during human evolution.

    Science.gov (United States)

    Babbitt, Courtney C; Haygood, Ralph; Nielsen, William J; Wray, Gregory A

    2017-06-05

    Despite evidence for adaptive changes in both gene expression and non-protein-coding, putatively regulatory regions of the genome during human evolution, the relationship between gene expression and adaptive changes in cis-regulatory regions remains unclear. Here we present new measurements of gene expression in five tissues of humans and chimpanzees, and use them to assess this relationship. We then compare our results with previous studies of adaptive noncoding changes, analyzing correlations at the level of gene ontology groups, in order to gain statistical power to detect correlations. Consistent with previous studies, we find little correlation between gene expression and adaptive noncoding changes at the level of individual genes; however, we do find significant correlations at the level of biological function ontology groups. The types of function include processes regulated by specific transcription factors, responses to genetic or chemical perturbations, and differentiation of cell types within the immune system. Among functional categories co-enriched with both differential expression and noncoding adaptation, prominent themes include cancer, particularly epithelial cancers, and neural development and function.

  11. Parameter identification of PEMFC model based on hybrid adaptive differential evolution algorithm

    International Nuclear Information System (INIS)

    Sun, Zhe; Wang, Ning; Bi, Yunrui; Srinivasan, Dipti

    2015-01-01

    In this paper, a HADE (hybrid adaptive differential evolution) algorithm is proposed for the identification problem of PEMFC (proton exchange membrane fuel cell). Inspired by biological genetic strategy, a novel adaptive scaling factor and a dynamic crossover probability are presented to improve the adaptive and dynamic performance of differential evolution algorithm. Moreover, two kinds of neighborhood search operations based on the bee colony foraging mechanism are introduced for enhancing local search efficiency. Through testing the benchmark functions, the proposed algorithm exhibits better performance in convergent accuracy and speed. Finally, the HADE algorithm is applied to identify the nonlinear parameters of PEMFC stack model. Through experimental comparison with other identified methods, the PEMFC model based on the HADE algorithm shows better performance. - Highlights: • We propose a hybrid adaptive differential evolution algorithm (HADE). • The search efficiency is enhanced in low and high dimension search space. • The effectiveness is confirmed by testing benchmark functions. • The identification of the PEMFC model is conducted by adopting HADE.

  12. Trans gene regulation in adaptive evolution: a genetic algorithm model.

    Science.gov (United States)

    Behera, N; Nanjundiah, V

    1997-09-21

    This is a continuation of earlier studies on the evolution of infinite populations of haploid genotypes within a genetic algorithm framework. We had previously explored the evolutionary consequences of the existence of indeterminate-"plastic"-loci, where a plastic locus had a finite probability in each generation of functioning (being switched "on") or not functioning (being switched "off"). The relative probabilities of the two outcomes were assigned on a stochastic basis. The present paper examines what happens when the transition probabilities are biased by the presence of regulatory genes. We find that under certain conditions regulatory genes can improve the adaptation of the population and speed up the rate of evolution (on occasion at the cost of lowering the degree of adaptation). Also, the existence of regulatory loci potentiates selection in favour of plasticity. There is a synergistic effect of regulatory genes on plastic alleles: the frequency of such alleles increases when regulatory loci are present. Thus, phenotypic selection alone can be a potentiating factor in a favour of better adaptation. Copyright 1997 Academic Press Limited.

  13. Farmers Ideas of Climate Change and Strategies for Adaptation in ...

    African Journals Online (AJOL)

    Farmers Ideas of Climate Change and Strategies for Adaptation in Northern Part of Katsina State. ... The study reveals that changes in temperature and precipitation cause changes in crop varieties, changes in planting dates, a shorter growing season, and increased use of water conservation techniques. Various adaptation ...

  14. Adaptation strategies of airline travel agencies to the dynamics of ...

    African Journals Online (AJOL)

    The role of airline travel agencies in a changing operational environment depends on their ability to adapt and survive in the airline travel industry. This paper examines the adaptation strategies airline travel agencies adopt to remain in business. Data for this paper was obtained through multi-stage sampling system that ...

  15. Adaptive evolution of defense ability leads to diversification of prey species.

    Science.gov (United States)

    Zu, Jian; Wang, Jinliang; Du, Jianqiang

    2014-06-01

    In this paper, by using the adaptive dynamics approach, we investigate how the adaptive evolution of defense ability promotes the diversity of prey species in an initial one-prey-two-predator community. We assume that the prey species can evolve to a safer strategy such that it can reduce the predation risk, but a prey with a high defense ability for one predator may have a low defense ability for the other and vice versa. First, by using the method of critical function analysis, we find that if the trade-off is convex in the vicinity of the evolutionarily singular strategy, then this singular strategy is a continuously stable strategy. However, if the trade-off is weakly concave near the singular strategy and the competition between the two predators is relatively weak, then the singular strategy may be an evolutionary branching point. Second, we find that after the branching has occurred in the prey strategy, if the trade-off curve is globally concave, then the prey species might eventually evolve into two specialists, each caught by only one predator species. However, if the trade-off curve is convex-concave-convex, the prey species might eventually branch into two partial specialists, each being caught by both of the two predators and they can stably coexist on the much longer evolutionary timescale.

  16. A Self Adaptive Differential Evolution Algorithm for Global Optimization

    Science.gov (United States)

    Kumar, Pravesh; Pant, Millie

    This paper presents a new Differential Evolution algorithm based on hybridization of adaptive control parameters and trigonometric mutation. First we propose a self adaptive DE named ADE where choice of control parameter F and Cr is not fixed at some constant value but is taken iteratively. The proposed algorithm is further modified by applying trigonometric mutation in it and the corresponding algorithm is named as ATDE. The performance of ATDE is evaluated on the set of 8 benchmark functions and the results are compared with the classical DE algorithm in terms of average fitness function value, number of function evaluations, convergence time and success rate. The numerical result shows the competence of the proposed algorithm.

  17. Adaptive Multiscale Modeling of Geochemical Impacts on Fracture Evolution

    Science.gov (United States)

    Molins, S.; Trebotich, D.; Steefel, C. I.; Deng, H.

    2016-12-01

    Understanding fracture evolution is essential for many subsurface energy applications, including subsurface storage, shale gas production, fracking, CO2 sequestration, and geothermal energy extraction. Geochemical processes in particular play a significant role in the evolution of fractures through dissolution-driven widening, fines migration, and/or fracture sealing due to precipitation. One obstacle to understanding and exploiting geochemical fracture evolution is that it is a multiscale process. However, current geochemical modeling of fractures cannot capture this multi-scale nature of geochemical and mechanical impacts on fracture evolution, and is limited to either a continuum or pore-scale representation. Conventional continuum-scale models treat fractures as preferential flow paths, with their permeability evolving as a function (often, a cubic law) of the fracture aperture. This approach has the limitation that it oversimplifies flow within the fracture in its omission of pore scale effects while also assuming well-mixed conditions. More recently, pore-scale models along with advanced characterization techniques have allowed for accurate simulations of flow and reactive transport within the pore space (Molins et al., 2014, 2015). However, these models, even with high performance computing, are currently limited in their ability to treat tractable domain sizes (Steefel et al., 2013). Thus, there is a critical need to develop an adaptive modeling capability that can account for separate properties and processes, emergent and otherwise, in the fracture and the rock matrix at different spatial scales. Here we present an adaptive modeling capability that treats geochemical impacts on fracture evolution within a single multiscale framework. Model development makes use of the high performance simulation capability, Chombo-Crunch, leveraged by high resolution characterization and experiments. The modeling framework is based on the adaptive capability in Chombo

  18. Iran's Sea Power Strategy: Goals and Evolution

    National Research Council Canada - National Science Library

    Walker, John

    1997-01-01

    This thesis examines the intent of Iran's sea power strategy using a multipart analysis including a historical review of the transition of Iran's naval power through the Iranian Revolution, Iran-Iraq...

  19. Design of 2-D Recursive Filters Using Self-adaptive Mutation Differential Evolution Algorithm

    Directory of Open Access Journals (Sweden)

    Lianghong Wu

    2011-08-01

    Full Text Available This paper investigates a novel approach to the design of two-dimensional recursive digital filters using differential evolution (DE algorithm. The design task is reformulated as a constrained minimization problem and is solved by an Self-adaptive Mutation DE algorithm (SAMDE, which adopts an adaptive mutation operator that combines with the advantages of the DE/rand/1/bin strategy and the DE/best/2/bin strategy. As a result, its convergence performance is improved greatly. Numerical experiment results confirm the conclusion. The proposedSAMDE approach is effectively applied to test a numerical example and is compared with previous design methods. The computational experiments show that the SAMDE approach can obtain better results than previous design methods.

  20. Gene loss, adaptive evolution and the co-evolution of plumage coloration genes with opsins in birds.

    Science.gov (United States)

    Borges, Rui; Khan, Imran; Johnson, Warren E; Gilbert, M Thomas P; Zhang, Guojie; Jarvis, Erich D; O'Brien, Stephen J; Antunes, Agostinho

    2015-10-06

    The wide range of complex photic systems observed in birds exemplifies one of their key evolutionary adaptions, a well-developed visual system. However, genomic approaches have yet to be used to disentangle the evolutionary mechanisms that govern evolution of avian visual systems. We performed comparative genomic analyses across 48 avian genomes that span extant bird phylogenetic diversity to assess evolutionary changes in the 17 representatives of the opsin gene family and five plumage coloration genes. Our analyses suggest modern birds have maintained a repertoire of up to 15 opsins. Synteny analyses indicate that PARA and PARIE pineal opsins were lost, probably in conjunction with the degeneration of the parietal organ. Eleven of the 15 avian opsins evolved in a non-neutral pattern, confirming the adaptive importance of vision in birds. Visual conopsins sw1, sw2 and lw evolved under negative selection, while the dim-light RH1 photopigment diversified. The evolutionary patterns of sw1 and of violet/ultraviolet sensitivity in birds suggest that avian ancestors had violet-sensitive vision. Additionally, we demonstrate an adaptive association between the RH2 opsin and the MC1R plumage color gene, suggesting that plumage coloration has been photic mediated. At the intra-avian level we observed some unique adaptive patterns. For example, barn owl showed early signs of pseudogenization in RH2, perhaps in response to nocturnal behavior, and penguins had amino acid deletions in RH2 sites responsible for the red shift and retinal binding. These patterns in the barn owl and penguins were convergent with adaptive strategies in nocturnal and aquatic mammals, respectively. We conclude that birds have evolved diverse opsin adaptations through gene loss, adaptive selection and coevolution with plumage coloration, and that differentiated selective patterns at the species level suggest novel photic pressures to influence evolutionary patterns of more-recent lineages.

  1. The Evolution of Exploitation Strategies by Myrmecophiles

    DEFF Research Database (Denmark)

    Schär, Sämi

    than outside ant nests (M. rubra) as well. This fungus can kill ant associated lycaenid larvae, justifying the assumption that these benefit from the entomopathogen poor environment of ant nests. This could explain why natural selection may act in favour of this strategy. In the third chapter I......Myrmecophiles are animals which have evolved to live in the nests of ants. This life history strategy appears in animals as different as insects, spiders, snails, crustaceans and even snakes. Myrmecophiles are very speciose with estimates of up to 100'000 species, which raises the question why...... this strategy has evolved so frequently and is maintained by natural selection. The type of association between Myrmecophiles and ants ranges from mutualistic through to parasitic. These types of symbioses can also be found between and within species of ants. Ant associations can therefore be broadly...

  2. Adaptive evolution of the vertebrate skeletal muscle sodium channel

    Directory of Open Access Journals (Sweden)

    Jian Lu

    2011-01-01

    Full Text Available Tetrodotoxin (TTX is a highly potent neurotoxin that blocks the action potential by selectively binding to voltage-gated sodium channels (Na v. The skeletal muscle Na v (Na v1.4 channels in most pufferfish species and certain North American garter snakes are resistant to TTX, whereas in most mammals they are TTX-sensitive. It still remains unclear as to whether the difference in this sensitivity among the various vertebrate species can be associated with adaptive evolution. In this study, we investigated the adaptive evolution of the vertebrate Na v1.4 channels. By means of the CODEML program of the PAML 4.3 package, the lineages of both garter snakes and pufferfishes were denoted to be under positive selection. The positively selected sites identified in the p-loop regions indicated their involvement in Na v1.4 channel sensitivity to TTX. Most of these sites were located in the intracellular regions of the Na v1.4 channel, thereby implying the possible association of these regions with the regulation of voltage-sensor movement.

  3. Mechanisms of adaptive evolution. Darwinism and Lamarckism restated.

    Science.gov (United States)

    Aboitiz, F

    1992-07-01

    This article discusses the conceptual basis of the different mechanisms of adaptive evolution. It is argued that only two such mechanisms may conceivably exist, Lamarckism and Darwinism. Darwinism is the fundamental process generating the diversity of species. Some aspects of the gene-centered approach to Darwinism are questioned, since they do not account for the generation of biological diversity. Diversity in biological design must be explained in relation to the diversity of interactions of organisms (or other higher-level units) with their environment. This aspect is usually overlooked in gene-centered views of evolution. A variant of the gene-selectionist approach has been proposed to account for the spread of cultural traits in human societies. Alternatively, I argue that social evolution is rather driven by what I call pseudo-Lamarckian inheritance. Finally, I argue that Lamarckian and pseudo-Lamarckian inheritance are just special cases of faithful replication which are found in the development of some higher-order units, such as multicellular organisms and human societies.

  4. Adaptive Patterns of Mitogenome Evolution Are Associated with the Loss of Shell Scutes in Turtles.

    Science.gov (United States)

    Escalona, Tibisay; Weadick, Cameron J; Antunes, Agostinho

    2017-10-01

    The mitochondrial genome encodes several protein components of the oxidative phosphorylation (OXPHOS) pathway and is critical for aerobic respiration. These proteins have evolved adaptively in many taxa, but linking molecular-level patterns with higher-level attributes (e.g., morphology, physiology) remains a challenge. Turtles are a promising system for exploring mitochondrial genome evolution as different species face distinct respiratory challenges and employ multiple strategies for ensuring efficient respiration. One prominent adaptation to a highly aquatic lifestyle in turtles is the secondary loss of keratenized shell scutes (i.e., soft-shells), which is associated with enhanced swimming ability and, in some species, cutaneous respiration. We used codon models to examine patterns of selection on mitochondrial protein-coding genes along the three turtle lineages that independently evolved soft-shells. We found strong evidence for positive selection along the branches leading to the pig-nosed turtle (Carettochelys insculpta) and the softshells clade (Trionychidae), but only weak evidence for the leatherback (Dermochelys coriacea) branch. Positively selected sites were found to be particularly prevalent in OXPHOS Complex I proteins, especially subunit ND2, along both positively selected lineages, consistent with convergent adaptive evolution. Structural analysis showed that many of the identified sites are within key regions or near residues involved in proton transport, indicating that positive selection may have precipitated substantial changes in mitochondrial function. Overall, our study provides evidence that physiological challenges associated with adaptation to a highly aquatic lifestyle have shaped the evolution of the turtle mitochondrial genome in a lineage-specific manner. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  5. On the Adaptive Design Rules of Biochemical Networks in Evolution

    Directory of Open Access Journals (Sweden)

    Bor-Sen Chen

    2007-01-01

    Full Text Available Biochemical networks are the backbones of physiological systems of organisms. Therefore, a biochemical network should be sufficiently robust (not sensitive to tolerate genetic mutations and environmental changes in the evolutionary process. In this study, based on the robustness and sensitivity criteria of biochemical networks, the adaptive design rules are developed for natural selection in the evolutionary process. This will provide insights into the robust adaptive mechanism of biochemical networks in the evolutionary process. We find that if a mutated biochemical network satisfies the robustness and sensitivity criteria of natural selection, there is a high probability for the biochemical network to prevail during natural selection in the evolutionary process. Since there are various mutated biochemical networks that can satisfy these criteria but have some differences in phenotype, the biochemical networks increase their diversities in the evolutionary process. The robustness of a biochemical network enables co-option so that new phenotypes can be generated in evolution. The proposed robust adaptive design rules of natural selection gain much insight into the evolutionary mechanism and provide a systematic robust biochemical circuit design method of biochemical networks for biotechnological and therapeutic purposes in the future.

  6. On the adaptivity and complexity embedded into differential evolution

    International Nuclear Information System (INIS)

    Senkerik, Roman; Pluhacek, Michal; Jasek, Roman; Zelinka, Ivan

    2016-01-01

    This research deals with the comparison of the two modern approaches for evolutionary algorithms, which are the adaptivity and complex chaotic dynamics. This paper aims on the investigations on the chaos-driven Differential Evolution (DE) concept. This paper is aimed at the embedding of discrete dissipative chaotic systems in the form of chaotic pseudo random number generators for the DE and comparing the influence to the performance with the state of the art adaptive representative jDE. This research is focused mainly on the possible disadvantages and advantages of both compared approaches. Repeated simulations for Lozi map driving chaotic systems were performed on the simple benchmark functions set, which are more close to the real optimization problems. Obtained results are compared with the canonical not-chaotic and not adaptive DE. Results show that with used simple test functions, the performance of ChaosDE is better in the most cases than jDE and Canonical DE, furthermore due to the unique sequencing in CPRNG given by the hidden chaotic dynamics, thus better and faster selection of unique individuals from population, ChaosDE is faster.

  7. On the adaptivity and complexity embedded into differential evolution

    Science.gov (United States)

    Senkerik, Roman; Pluhacek, Michal; Zelinka, Ivan; Jasek, Roman

    2016-06-01

    This research deals with the comparison of the two modern approaches for evolutionary algorithms, which are the adaptivity and complex chaotic dynamics. This paper aims on the investigations on the chaos-driven Differential Evolution (DE) concept. This paper is aimed at the embedding of discrete dissipative chaotic systems in the form of chaotic pseudo random number generators for the DE and comparing the influence to the performance with the state of the art adaptive representative jDE. This research is focused mainly on the possible disadvantages and advantages of both compared approaches. Repeated simulations for Lozi map driving chaotic systems were performed on the simple benchmark functions set, which are more close to the real optimization problems. Obtained results are compared with the canonical not-chaotic and not adaptive DE. Results show that with used simple test functions, the performance of ChaosDE is better in the most cases than jDE and Canonical DE, furthermore due to the unique sequencing in CPRNG given by the hidden chaotic dynamics, thus better and faster selection of unique individuals from population, ChaosDE is faster.

  8. On the adaptivity and complexity embedded into differential evolution

    Energy Technology Data Exchange (ETDEWEB)

    Senkerik, Roman; Pluhacek, Michal; Jasek, Roman [Tomas Bata University in Zlin, Faculty of Applied Informatics, Nam T.G. Masaryka 5555, 760 01 Zlin, Czech Republic, senkerik@fai.utb.cz,pluhacek@fai.utb.cz (Czech Republic); Zelinka, Ivan [Technical University of Ostrava, Faculty of Electrical Engineering and Computer Science, 17. listopadu 15,708 33 Ostrava-Poruba, Czech Republic, ivan.zelinka@vsb.cz (Czech Republic)

    2016-06-08

    This research deals with the comparison of the two modern approaches for evolutionary algorithms, which are the adaptivity and complex chaotic dynamics. This paper aims on the investigations on the chaos-driven Differential Evolution (DE) concept. This paper is aimed at the embedding of discrete dissipative chaotic systems in the form of chaotic pseudo random number generators for the DE and comparing the influence to the performance with the state of the art adaptive representative jDE. This research is focused mainly on the possible disadvantages and advantages of both compared approaches. Repeated simulations for Lozi map driving chaotic systems were performed on the simple benchmark functions set, which are more close to the real optimization problems. Obtained results are compared with the canonical not-chaotic and not adaptive DE. Results show that with used simple test functions, the performance of ChaosDE is better in the most cases than jDE and Canonical DE, furthermore due to the unique sequencing in CPRNG given by the hidden chaotic dynamics, thus better and faster selection of unique individuals from population, ChaosDE is faster.

  9. NEW CO-EVOLUTION STRATEGIES OF THIRD MILLENNIUM; METHODOLOGICAL ASPECT

    Directory of Open Access Journals (Sweden)

    E. K. Bulygo

    2006-01-01

    Full Text Available The paper is devoted to an application of the co-evolution methodology to the social space. Principles of instability and non-linearity that are typical for contemporary natural science are used as a theoretical background of a new social methodology. Authors try to prove that the co-evolution strategy has a long pre-history in the ancient oriental philosophy and manifests itself in forms of modem culture

  10. Adaptive Landing Gear: Optimum Control Strategy and Potential for Improvement

    Directory of Open Access Journals (Sweden)

    Grzegorz Mikułowski

    2009-01-01

    Full Text Available An adaptive landing gear is a landing gear (LG capable of active adaptation to particular landing conditions by means of controlled hydraulic force. The objective of the adaptive control is to mitigate the peak force transferred to the aircraft structure during touch-down, and thus to limit the structural fatigue factor. This paper investigates the ultimate limits for improvement due to various strategies of active control. Five strategies are proposed and investigated numerically using a~validated model of a real, passive landing gear as a reference. Potential for improvement is estimated statistically in terms of the mean and median (significant peak strut forces as well as in terms of the extended safe sinking velocity range. Three control strategies are verified experimentally using a laboratory test stand.

  11. Entrepreneurship ecosystem evolution strategy of Saudi Arabia

    Directory of Open Access Journals (Sweden)

    Muhammad Rahatullah Khan

    2016-10-01

    Full Text Available In majority of times when a potential start-up strikes a brilliant business idea, he/she has little knowledge of ‘how to move from there’. They lack information on the stakeholders of entrepreneurship ecosystem who can help and assist these startups in numerous ways and help them materialize their concepts. Availability of this information will help the ecosystem stakeholders to avoid replication and duplication of efforts. Similarly, knowledge of status quo helps identify opportunities and supports plan development to endeavor through right strategy for the start-up. Critical review of existing initiatives of Saudi Arabia for entrepreneurship growth and identification of the existing stakeholders of the entrepreneurship in the country is conducted. Similarly their work and potential for practicable interventions to further entrepreneurship reflecting country’s economic development process is examined. This paper benefits from a cross sectional basic study of Saudi Arabia that utilized primary and secondary sources to discover the initiatives, understand entrepreneurship growth and then map the national entrepreneurship ecosystem. A number of interviews from CEO’s, General Managers and other senior executives were carried out to know the role of the different organizations in entrepreneurship growth. It was coupled with a detailed secondary research from existing resources. It has been identified that the ecosystem is swiftly expanding but yet under development and infancy stage where the institutions are prospering. The research is based on country analysis. The paper also shows that the Saudi Arabian government has taken proactive stance in developing the entrepreneurship ecosystem and startup landscape and highlights the transformation of the ecosystem strategy.

  12. Comparative genomics reveals insights into avian genome evolution and adaptation

    Science.gov (United States)

    Zhang, Guojie; Li, Cai; Li, Qiye; Li, Bo; Larkin, Denis M.; Lee, Chul; Storz, Jay F.; Antunes, Agostinho; Greenwold, Matthew J.; Meredith, Robert W.; Ödeen, Anders; Cui, Jie; Zhou, Qi; Xu, Luohao; Pan, Hailin; Wang, Zongji; Jin, Lijun; Zhang, Pei; Hu, Haofu; Yang, Wei; Hu, Jiang; Xiao, Jin; Yang, Zhikai; Liu, Yang; Xie, Qiaolin; Yu, Hao; Lian, Jinmin; Wen, Ping; Zhang, Fang; Li, Hui; Zeng, Yongli; Xiong, Zijun; Liu, Shiping; Zhou, Long; Huang, Zhiyong; An, Na; Wang, Jie; Zheng, Qiumei; Xiong, Yingqi; Wang, Guangbiao; Wang, Bo; Wang, Jingjing; Fan, Yu; da Fonseca, Rute R.; Alfaro-Núñez, Alonzo; Schubert, Mikkel; Orlando, Ludovic; Mourier, Tobias; Howard, Jason T.; Ganapathy, Ganeshkumar; Pfenning, Andreas; Whitney, Osceola; Rivas, Miriam V.; Hara, Erina; Smith, Julia; Farré, Marta; Narayan, Jitendra; Slavov, Gancho; Romanov, Michael N; Borges, Rui; Machado, João Paulo; Khan, Imran; Springer, Mark S.; Gatesy, John; Hoffmann, Federico G.; Opazo, Juan C.; Håstad, Olle; Sawyer, Roger H.; Kim, Heebal; Kim, Kyu-Won; Kim, Hyeon Jeong; Cho, Seoae; Li, Ning; Huang, Yinhua; Bruford, Michael W.; Zhan, Xiangjiang; Dixon, Andrew; Bertelsen, Mads F.; Derryberry, Elizabeth; Warren, Wesley; Wilson, Richard K; Li, Shengbin; Ray, David A.; Green, Richard E.; O’Brien, Stephen J.; Griffin, Darren; Johnson, Warren E.; Haussler, David; Ryder, Oliver A.; Willerslev, Eske; Graves, Gary R.; Alström, Per; Fjeldså, Jon; Mindell, David P.; Edwards, Scott V.; Braun, Edward L.; Rahbek, Carsten; Burt, David W.; Houde, Peter; Zhang, Yong; Yang, Huanming; Wang, Jian; Jarvis, Erich D.; Gilbert, M. Thomas P.; Wang, Jun

    2015-01-01

    Birds are the most species-rich class of tetrapod vertebrates and have wide relevance across many research fields. We explored bird macroevolution using full genomes from 48 avian species representing all major extant clades. The avian genome is principally characterized by its constrained size, which predominantly arose because of lineage-specific erosion of repetitive elements, large segmental deletions, and gene loss. Avian genomes furthermore show a remarkably high degree of evolutionary stasis at the levels of nucleotide sequence, gene synteny, and chromosomal structure. Despite this pattern of conservation, we detected many non-neutral evolutionary changes in protein-coding genes and noncoding regions. These analyses reveal that pan-avian genomic diversity covaries with adaptations to different lifestyles and convergent evolution of traits. PMID:25504712

  13. Evolution and adaptation in Pseudomonas aeruginosa biofilms driven by mismatch repair system-deficient mutators.

    Directory of Open Access Journals (Sweden)

    Adela M Luján

    Full Text Available Pseudomonas aeruginosa is an important opportunistic pathogen causing chronic airway infections, especially in cystic fibrosis (CF patients. The majority of the CF patients acquire P. aeruginosa during early childhood, and most of them develop chronic infections resulting in severe lung disease, which are rarely eradicated despite intensive antibiotic therapy. Current knowledge indicates that three major adaptive strategies, biofilm development, phenotypic diversification, and mutator phenotypes [driven by a defective mismatch repair system (MRS], play important roles in P. aeruginosa chronic infections, but the relationship between these strategies is still poorly understood. We have used the flow-cell biofilm model system to investigate the impact of the mutS associated mutator phenotype on development, dynamics, diversification and adaptation of P. aeruginosa biofilms. Through competition experiments we demonstrate for the first time that P. aeruginosa MRS-deficient mutators had enhanced adaptability over wild-type strains when grown in structured biofilms but not as planktonic cells. This advantage was associated with enhanced micro-colony development and increased rates of phenotypic diversification, evidenced by biofilm architecture features and by a wider range and proportion of morphotypic colony variants, respectively. Additionally, morphotypic variants generated in mutator biofilms showed increased competitiveness, providing further evidence for mutator-driven adaptive evolution in the biofilm mode of growth. This work helps to understand the basis for the specific high proportion and role of mutators in chronic infections, where P. aeruginosa develops in biofilm communities.

  14. Prolonged Adaptive Evolution of a Defensive Gene in the Solanaceae.

    Science.gov (United States)

    Rausher, Mark D; Huang, Jie

    2016-01-01

    Although plants and their natural enemies may coevolve for prolonged periods, little is known about how long individual plant defensive genes are involved in the coevolutionary process. We address this issue by examining patterns of selection on the defensive gene threonine deaminase (TD). Tomato (Solanum lycopersicum) has two copies of this gene. One performs the canonical housekeeping function in amino acid metabolism of catalyzing the first reaction in the conversion of threonine to isoleucine. The second copy functions as an antinutritive defense against lepidopteran herbivores by depleting threonine in the insect gut. Wild tobacco (Nicotiana attenuata) also contains a defensive copy. We show that a single copy of TD underwent two or three duplications near the base of the Solanaceae. One copy retains the housekeeping function, whereas a second copy evolved defensive functions. Positive selection occurred on the branch of the TD2 gene tree subtending the common ancestor of the Nicotianoideae and Solanoideae. It also occurred within the Solanoideae clade but not within the Nicotianoideae clade. Finally, it occurred on most branches leading from the common ancestor to S. lycopersicum. Based on recent calibrations of the Solanaceae phylogeny, TD2 experienced adaptive substitutions for a period of 30-50 My. We suggest that the most likely explanation for this result is fluctuating herbivore abundances: When herbivores are rare, relaxed selection increases the likelihood that slightly disadvantageous mutations will be fixed by drift; when herbivores are common, increased selection causes the evolution of compensatory adaptive mutations. Alternative explanations are also discussed. © The Author 2015. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  15. Research on Taxi Driver Strategy Game Evolution with Carpooling Detour

    Directory of Open Access Journals (Sweden)

    Wei Zhang

    2018-01-01

    Full Text Available For the problem of taxi carpooling detour, this paper studies driver strategy choice with carpooling detour. The model of taxi driver strategy evolution with carpooling detour is built based on prospect theory and evolution game theory. Driver stable strategies are analyzed under the conditions of complaint mechanism and absence of mechanism, respectively. The results show that passenger’s complaint mechanism can effectively decrease the phenomenon of driver refusing passengers with carpooling detour. When probability of passenger complaint reaches a certain level, the stable strategy of driver is to take carpooling detour passengers. Meanwhile, limiting detour distance and easing traffic congestion can decrease the possibility of refusing passengers. These conclusions have a certain guiding significance to formulating taxi policy.

  16. Adaptive evolution of facial colour patterns in Neotropical primates.

    Science.gov (United States)

    Santana, Sharlene E; Lynch Alfaro, Jessica; Alfaro, Michael E

    2012-06-07

    The rich diversity of primate faces has interested naturalists for over a century. Researchers have long proposed that social behaviours have shaped the evolution of primate facial diversity. However, the primate face constitutes a unique structure where the diverse and potentially competing functions of communication, ecology and physiology intersect, and the major determinants of facial diversity remain poorly understood. Here, we provide the first evidence for an adaptive role of facial colour patterns and pigmentation within Neotropical primates. Consistent with the hypothesis that facial patterns function in communication and species recognition, we find that species living in smaller groups and in sympatry with a higher number of congener species have evolved more complex patterns of facial colour. The evolution of facial pigmentation and hair length is linked to ecological factors, and ecogeographical rules related to UV radiation and thermoregulation are met by some facial regions. Our results demonstrate the interaction of behavioural and ecological factors in shaping one of the most outstanding facial diversities of any mammalian lineage.

  17. Critical dynamics in the evolution of stochastic strategies for the iterated prisoner's dilemma.

    Directory of Open Access Journals (Sweden)

    Dimitris Iliopoulos

    2010-10-01

    Full Text Available The observed cooperation on the level of genes, cells, tissues, and individuals has been the object of intense study by evolutionary biologists, mainly because cooperation often flourishes in biological systems in apparent contradiction to the selfish goal of survival inherent in Darwinian evolution. In order to resolve this paradox, evolutionary game theory has focused on the Prisoner's Dilemma (PD, which incorporates the essence of this conflict. Here, we encode strategies for the iterated Prisoner's Dilemma (IPD in terms of conditional probabilities that represent the response of decision pathways given previous plays. We find that if these stochastic strategies are encoded as genes that undergo Darwinian evolution, the environmental conditions that the strategies are adapting to determine the fixed point of the evolutionary trajectory, which could be either cooperation or defection. A transition between cooperative and defective attractors occurs as a function of different parameters such as mutation rate, replacement rate, and memory, all of which affect a player's ability to predict an opponent's behavior. These results imply that in populations of players that can use previous decisions to plan future ones, cooperation depends critically on whether the players can rely on facing the same strategies that they have adapted to. Defection, on the other hand, is the optimal adaptive response in environments that change so quickly that the information gathered from previous plays cannot usefully be integrated for a response.

  18. Adaptive Evolution of CENP-A in Percid Fishes

    Directory of Open Access Journals (Sweden)

    Harriet N. A. Abbey

    2015-07-01

    Full Text Available Centromeric protein A (CENP-A is the epigenetic determinant of centromeres. This protein has been shown to be adaptively evolving in a number of animal and plant species. In a previous communication we were able to demonstrate that signs of adaptive evolution were detected in the comparison of CENP-A sequences from three percid fish species. In this study we isolated the CENP-A gene from eight additional species from the Percidae family. With these sequences and those previously obtained, we carried out a more robust statistical analysis of codon specific positive selection in CENP-A coding sequences of eleven percid species. We were able to demonstrate that at least two amino acid positions within the N-terminal tail are under strong positive selection and that one of these positions is potentially a substrate for phosphorylation. While nonsynonymous substitutions were detected in the histone fold domain, these were not statistically supported as resulting from positive selection.

  19. An analysis of climatic impacts and adaptation strategies in Tanzania

    CSIR Research Space (South Africa)

    Ojoyi, MM

    2015-03-01

    Full Text Available International Journal of Climate Change Strategies and Management An analysis of climatic impacts and adaptation strategies in Tanzania Mercy M. Ojoyi School of Environmental Sciences, University of KwaZulu-Natal, Pietermaritzburg, South Africa... of feedback results from analysis of variance tests conducted. Major indicators of climate variability and change include: increased dry spells (39.7 per cent), drying of rivers (34.7 per cent), a reduction in water flows (14.6 per cent) and poor economy...

  20. Stepping strategies for regulating gait adaptability and stability.

    Science.gov (United States)

    Hak, Laura; Houdijk, Han; Steenbrink, Frans; Mert, Agali; van der Wurff, Peter; Beek, Peter J; van Dieën, Jaap H

    2013-03-15

    Besides a stable gait pattern, gait in daily life requires the capability to adapt this pattern in response to environmental conditions. The purpose of this study was to elucidate the anticipatory strategies used by able-bodied people to attain an adaptive gait pattern, and how these strategies interact with strategies used to maintain gait stability. Ten healthy subjects walked in a Computer Assisted Rehabilitation ENvironment (CAREN). To provoke an adaptive gait pattern, subjects had to hit virtual targets, with markers guided by their knees, while walking on a self-paced treadmill. The effects of walking with and without this task on walking speed, step length, step frequency, step width and the margins of stability (MoS) were assessed. Furthermore, these trials were performed with and without additional continuous ML platform translations. When an adaptive gait pattern was required, subjects decreased step length (padaptations resulted in the preservation of equal MoS between trials, despite the disturbing influence of the gait adaptability task. When the gait adaptability task was combined with the balance perturbation subjects further decreased step length, as evidenced by a significant interaction between both manipulations (p=0.012). In conclusion, able-bodied people reduce step length and increase step width during walking conditions requiring a high level of both stability and adaptability. Although an increase in step frequency has previously been found to enhance stability, a faster movement, which would coincide with a higher step frequency, hampers accuracy and may consequently limit gait adaptability. Copyright © 2012 Elsevier Ltd. All rights reserved.

  1. Adaptive evolution of the matrix extracellular phosphoglycoprotein in mammals

    Directory of Open Access Journals (Sweden)

    Machado João

    2011-11-01

    Full Text Available Abstract Background Matrix extracellular phosphoglycoprotein (MEPE belongs to a family of small integrin-binding ligand N-linked glycoproteins (SIBLINGs that play a key role in skeleton development, particularly in mineralization, phosphate regulation and osteogenesis. MEPE associated disorders cause various physiological effects, such as loss of bone mass, tumors and disruption of renal function (hypophosphatemia. The study of this developmental gene from an evolutionary perspective could provide valuable insights on the adaptive diversification of morphological phenotypes in vertebrates. Results Here we studied the adaptive evolution of the MEPE gene in 26 Eutherian mammals and three birds. The comparative genomic analyses revealed a high degree of evolutionary conservation of some coding and non-coding regions of the MEPE gene across mammals indicating a possible regulatory or functional role likely related with mineralization and/or phosphate regulation. However, the majority of the coding region had a fast evolutionary rate, particularly within the largest exon (1467 bp. Rodentia and Scandentia had distinct substitution rates with an increased accumulation of both synonymous and non-synonymous mutations compared with other mammalian lineages. Characteristics of the gene (e.g. biochemical, evolutionary rate, and intronic conservation differed greatly among lineages of the eight mammalian orders. We identified 20 sites with significant positive selection signatures (codon and protein level outside the main regulatory motifs (dentonin and ASARM suggestive of an adaptive role. Conversely, we find three sites under selection in the signal peptide and one in the ASARM motif that were supported by at least one selection model. The MEPE protein tends to accumulate amino acids promoting disorder and potential phosphorylation targets. Conclusion MEPE shows a high number of selection signatures, revealing the crucial role of positive selection in the

  2. Adaptive evolution of Saccharomyces cerevisiae with enhanced ethanol tolerance for Chinese rice wine fermentation.

    Science.gov (United States)

    Chen, Shuang; Xu, Yan

    2014-08-01

    High tolerance towards ethanol is a desirable property for the Saccharomyces cerevisiae strains used in the alcoholic beverage industry. To improve the ethanol tolerance of an industrial Chinese rice wine yeast, a sequential batch fermentation strategy was used to adaptively evolve a chemically mutagenized Chinese rice wine G85 strain. The high level of ethanol produced under Chinese rice wine-like fermentation conditions was used as the selective pressure. After adaptive evolution of approximately 200 generations, mutant G85X-8 was isolated and shown to have markedly increased ethanol tolerance. The evolved strain also showed higher osmotic and temperature tolerances than the parental strain. Laboratory Chinese rice wine fermentation showed that the evolved G85X-8 strain was able to catabolize sugars more completely than the parental G85 strain. A higher level of yeast cell activity was found in the fermentation mash produced by the evolved strain, but the aroma profiles were similar between the evolved and parental strains. The improved ethanol tolerance in the evolved strain might be ascribed to the altered fatty acids composition of the cell membrane and higher intracellular trehalose concentrations. These results suggest that adaptive evolution is an efficient approach for the non-recombinant modification of industrial yeast strains.

  3. Accelerating Markov chain Monte Carlo simulation by differential evolution with self-adaptive randomized subspace sampling

    Energy Technology Data Exchange (ETDEWEB)

    Vrugt, Jasper A [Los Alamos National Laboratory; Hyman, James M [Los Alamos National Laboratory; Robinson, Bruce A [Los Alamos National Laboratory; Higdon, Dave [Los Alamos National Laboratory; Ter Braak, Cajo J F [NETHERLANDS; Diks, Cees G H [UNIV OF AMSTERDAM

    2008-01-01

    Markov chain Monte Carlo (MCMC) methods have found widespread use in many fields of study to estimate the average properties of complex systems, and for posterior inference in a Bayesian framework. Existing theory and experiments prove convergence of well constructed MCMC schemes to the appropriate limiting distribution under a variety of different conditions. In practice, however this convergence is often observed to be disturbingly slow. This is frequently caused by an inappropriate selection of the proposal distribution used to generate trial moves in the Markov Chain. Here we show that significant improvements to the efficiency of MCMC simulation can be made by using a self-adaptive Differential Evolution learning strategy within a population-based evolutionary framework. This scheme, entitled DiffeRential Evolution Adaptive Metropolis or DREAM, runs multiple different chains simultaneously for global exploration, and automatically tunes the scale and orientation of the proposal distribution in randomized subspaces during the search. Ergodicity of the algorithm is proved, and various examples involving nonlinearity, high-dimensionality, and multimodality show that DREAM is generally superior to other adaptive MCMC sampling approaches. The DREAM scheme significantly enhances the applicability of MCMC simulation to complex, multi-modal search problems.

  4. Niche evolution and adaptive radiation: Testing the order of trait divergence

    Science.gov (United States)

    Ackerly, D.D.; Schwilk, D.W.; Webb, C.O.

    2006-01-01

    In the course of an adaptive radiation, the evolution of niche parameters is of particular interest for understanding modes of speciation and the consequences for coexistence of related species within communities. We pose a general question: In the course of an evolutionary radiation, do traits related to within-community niche differences (?? niche) evolve before or after differentiation of macrohabitat affinity or climatic tolerances (?? niche)? Here we introduce a new test to address this question, based on a modification of the method of independent contrasts. The divergence order test (DOT) is based on the average age of the nodes on a tree, weighted by the absolute magnitude of the contrast at each node for a particular trait. The comparison of these weighted averages reveals whether large divergences for one trait have occurred earlier or later in the course of diversification, relative to a second trait; significance is determined by bootstrapping from maximum-likelihood ancestral state reconstructions. The method is applied to the evolution of Ceanothus, a woody plant group in California, in which co-occurring species exhibit significant differences in a key leaf trait (specific leaf area) associated with contrasting physiological and life history strategies. Co-occurring species differ more for this trait than expected under a null model of community assembly. This ?? niche difference evolved early in the divergence of two major subclades within Ceanothus, whereas climatic distributions (?? niche traits) diversified later within each of the subclades. However, rapid evolution of climate parameters makes inferences of early divergence events highly uncertain, and differentiation of the ?? niche might have taken place throughout the evolution of the group, without leaving a clear phylogenetic signal. Similar patterns observed in several plant and animal groups suggest that early divergence of ?? niche traits might be a common feature of niche evolution in

  5. Determinants of climate change adaptive strategies among small ...

    African Journals Online (AJOL)

    Identified adaptation strategies used by farmers to mitigate the effect of climate change included planting beside the river(86%), planting disease and pest resistant crop (73%) and changes on planting and harvesting dates(63%). Results of Tobit regression analysis showed that level of education, farm size and access to ...

  6. Climate change adaptation strategies by small-scale farmers in ...

    African Journals Online (AJOL)

    Mburu

    SPSS) ... were financial constraints (93.4%), lack of relevant skills (74.5%) and lack of ... Key words: Climate change, small-scale farmers, adaptation strategies. ... investment in irrigation infrastructure, high post-harvest ..... 72.0 School drop out.

  7. Real-Time Adaptation of Influence Strategies in Online Selling

    NARCIS (Netherlands)

    Kaptein, M.C.; Parvinen, P.

    2014-01-01

    Real-time adjustments in online selling are becoming increasingly common. In this paper we describe a novel method of real-time adaptation, and introduce influence strategies as a useful level of analysis for personalization of online selling. The proposed method incorporates three perspectives on

  8. Impacts of climate change, variability and adaptation strategies on ...

    African Journals Online (AJOL)

    Impacts of climate change, variability and adaptation strategies on agriculture in semi arid areas of Tanzania: The case of Manyoni District in Singida Region, Tanzania. ... The changes have affected crops and livestock in a number of ways resulting in reduced productivity. Empirical analysis of rainfall suggest decreasing ...

  9. Climate Change Mitigation and Adaptation Strategies Used by ...

    African Journals Online (AJOL)

    The majority (73.6%) of the farmers opined that in recent times, flooding had increased which is an indication of climate change. Reduction in the use of generator to get power in the farmers' houses (69.1%) and crop rotation practices (67.3%) were mitigation and adaptation strategies employed by the farmers against the ...

  10. Climate change adaptation strategies by small-scale farmers in ...

    African Journals Online (AJOL)

    Mburu

    Climate change is a great environmental challenge facing humanity today. In Yatta District, residents report frequent crop failures, water shortages and relief food has become a frequent feature of their life. This study examines the adaptation strategies to climate change adopted by the dry-land farming communities in Yatta ...

  11. Impact assessment of adaptation options and strategies for coping ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    Impact assessment of adaptation options and strategies for coping with climate change on the livelihoods of pastoral and agro-pastoral communities in Sudan' Butana area. Ibrahim, Abdelhamed M.M.. URI: http://hdl.handle.net/10625/53410. Date: 2013-11 ...

  12. Climate change adaptation strategies by local farmers in Kilombero ...

    African Journals Online (AJOL)

    This article examines current adaptation strategies developed by local farmers against climate change effects in Kilombero District. Research questions guided the study include; what are the past and current climatic stresses? What are local farmers' perception on climate change and response to the adverse climatic ...

  13. Event driven adaptation, land use and human coping strategies

    DEFF Research Database (Denmark)

    Reenberg, Anette; Birch-Thomsen, Torben; Fog, Bjarne

    perceive cause-effect relationships between societal and environmental events and their individual and collective management of resources. The coupled human-environment timelines are used to discuss ways in which the local communities' adaptive resource management strategies have been employed in the face......The paper focuses on assessing the wider perspectives of adaptive resource management strategies in former subsistence agriculture societies in the SW Pacific. Firstly, we will briefly introduce the theoretical context related to the livelihood framework, adaptation to socio-environmental change...... and the concept of coupled human-environmental timelines. Secondly, with point of departure in a baseline characterization of Bellona Island derived from a comprehensive survey in the late 1960s and resent fieldwork in late 2006, we present the case of Bellona Island. Key issues addressed concern climatic events...

  14. Paradigms for adaptive statistical information designs: practical experiences and strategies.

    Science.gov (United States)

    Wang, Sue-Jane; Hung, H M James; O'Neill, Robert

    2012-11-10

    design. We highlight the substantial risk of planning the sample size for confirmatory trials when information is very uninformative and stipulate the advantages of adaptive statistical information designs for planning exploratory trials. Practical experiences and strategies as lessons learned from more recent adaptive design proposals will be discussed to pinpoint the improved utilities of adaptive design clinical trials and their potential to increase the chance of a successful drug development. Published 2012. This article is a US Government work and is in the public domain in the USA.

  15. Adaptive evolution of benzoxazinoids in wild emmer wheat, Triticum dicoccoides, at "Evolution Canyon", Mount Carmel, Israel.

    Science.gov (United States)

    Ben-Abu, Yuval; Beiles, Avigdor; Flom, Dvir; Nevo, Eviatar

    2018-01-01

    "Evolution Canyon" (ECI) at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unraveling evolution-in-action, highlighting the evolutionary processes of biodiversity evolution, adaptation, and incipient sympatric speciation. A major model organism in ECI is the tetraploid wild emmer wheat, Triticum dicoccoides (TD), the progenitor of cultivated emmer and durum wheat. TD displays dramatic interslope adaptive evolutionary divergence on the tropical, savannoid-hot and dry south-facing, "African" slope (AS), and on the temperate, forested, cool and humid, north-facing, "European" slope (ES), separated on average by 250 m. From the perspective of chemical evolution and metabolomics, it is important to unravel interslope divergence in biologically relevant secondary metabolites between the abutting slope populations. Here, in TD we examined hydroxamic acid (Hx), which is a family of secondary cereal metabolites, and plays a major role in defending the plant against fungi, insects and weeds. Our examination revealed that higher concentrations of DIBOA and DIMBOA were found in seedlings growing in the same greenhouse from seeds collected from the cool and humid forested ES, whereas the seedlings of seeds collected from the savannoid AS (both in root and shoot tissues), showed no DIMBOA. Remarkably, only DIBOA appears in both shoots and roots of the AS seedlings. It rises to a peak and then decreases in both organs and in seedlings from both slopes. The DIMBOA, which appears only in the ES seedlings, rises to a peak and decreases in the shoot, but increased and remained in a plateau in the root, till the end of the experiment. The results suggest stronger genetic resistance of defense compounds DIBOA and DIMBOA against biotic stresses (fungi and other pathogens) by ES seedlings. However, AS seedlings responded earlier but were to the same biotic stresses. The genetic difference found in AS seedlings was caused by the main adaptive selection

  16. Adaptive evolution of benzoxazinoids in wild emmer wheat, Triticum dicoccoides, at "Evolution Canyon", Mount Carmel, Israel.

    Directory of Open Access Journals (Sweden)

    Yuval Ben-Abu

    Full Text Available "Evolution Canyon" (ECI at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unraveling evolution-in-action, highlighting the evolutionary processes of biodiversity evolution, adaptation, and incipient sympatric speciation. A major model organism in ECI is the tetraploid wild emmer wheat, Triticum dicoccoides (TD, the progenitor of cultivated emmer and durum wheat. TD displays dramatic interslope adaptive evolutionary divergence on the tropical, savannoid-hot and dry south-facing, "African" slope (AS, and on the temperate, forested, cool and humid, north-facing, "European" slope (ES, separated on average by 250 m. From the perspective of chemical evolution and metabolomics, it is important to unravel interslope divergence in biologically relevant secondary metabolites between the abutting slope populations. Here, in TD we examined hydroxamic acid (Hx, which is a family of secondary cereal metabolites, and plays a major role in defending the plant against fungi, insects and weeds.Our examination revealed that higher concentrations of DIBOA and DIMBOA were found in seedlings growing in the same greenhouse from seeds collected from the cool and humid forested ES, whereas the seedlings of seeds collected from the savannoid AS (both in root and shoot tissues, showed no DIMBOA. Remarkably, only DIBOA appears in both shoots and roots of the AS seedlings. It rises to a peak and then decreases in both organs and in seedlings from both slopes. The DIMBOA, which appears only in the ES seedlings, rises to a peak and decreases in the shoot, but increased and remained in a plateau in the root, till the end of the experiment.The results suggest stronger genetic resistance of defense compounds DIBOA and DIMBOA against biotic stresses (fungi and other pathogens by ES seedlings. However, AS seedlings responded earlier but were to the same biotic stresses. The genetic difference found in AS seedlings was caused by the main adaptive

  17. Intelligent fault recognition strategy based on adaptive optimized multiple centers

    Science.gov (United States)

    Zheng, Bo; Li, Yan-Feng; Huang, Hong-Zhong

    2018-06-01

    For the recognition principle based optimized single center, one important issue is that the data with nonlinear separatrix cannot be recognized accurately. In order to solve this problem, a novel recognition strategy based on adaptive optimized multiple centers is proposed in this paper. This strategy recognizes the data sets with nonlinear separatrix by the multiple centers. Meanwhile, the priority levels are introduced into the multi-objective optimization, including recognition accuracy, the quantity of optimized centers, and distance relationship. According to the characteristics of various data, the priority levels are adjusted to ensure the quantity of optimized centers adaptively and to keep the original accuracy. The proposed method is compared with other methods, including support vector machine (SVM), neural network, and Bayesian classifier. The results demonstrate that the proposed strategy has the same or even better recognition ability on different distribution characteristics of data.

  18. An Adaptive Classification Strategy for Reliable Locomotion Mode Recognition

    Directory of Open Access Journals (Sweden)

    Ming Liu

    2017-09-01

    Full Text Available Algorithms for locomotion mode recognition (LMR based on surface electromyography and mechanical sensors have recently been developed and could be used for the neural control of powered prosthetic legs. However, the variations in input signals, caused by physical changes at the sensor interface and human physiological changes, may threaten the reliability of these algorithms. This study aimed to investigate the effectiveness of applying adaptive pattern classifiers for LMR. Three adaptive classifiers, i.e., entropy-based adaptation (EBA, LearnIng From Testing data (LIFT, and Transductive Support Vector Machine (TSVM, were compared and offline evaluated using data collected from two able-bodied subjects and one transfemoral amputee. The offline analysis indicated that the adaptive classifier could effectively maintain or restore the performance of the LMR algorithm when gradual signal variations occurred. EBA and LIFT were recommended because of their better performance and higher computational efficiency. Finally, the EBA was implemented for real-time human-in-the-loop prosthesis control. The online evaluation showed that the applied EBA effectively adapted to changes in input signals across sessions and yielded more reliable prosthesis control over time, compared with the LMR without adaptation. The developed novel adaptive strategy may further enhance the reliability of neurally-controlled prosthetic legs.

  19. Assessment of the effectiveness of flood adaptation strategies for HCMC

    Science.gov (United States)

    Lasage, R.; Veldkamp, T. I. E.; de Moel, H.; Van, T. C.; Phi, H. L.; Vellinga, P.; Aerts, J. C. J. H.

    2014-06-01

    Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, Asian cities in particular are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reduction measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea-level rise and socio-economic developments on flood risk for the flood-prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry- and wet proofing of buildings and elevating roads and buildings). A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage-damage curves for residential buildings. The model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in expected annual damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea-level scenarios and land-use scenarios. Together with information on costs of these strategies, we calculated the benefit-cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5% and 5%. The results of this modelling study indicate that the current flood risk in District 4 is USD 0.31 million per year, increasing up to USD 0.78 million per year in 2100. The net present value and benefit-cost ratios using a discount rate of 5 % range from USD -107 to -1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5% leads to an increase in both net present value and benefit-cost ratio. The adaptation strategies wet-proofing and dry-proofing generate the best results using these economic indicators. The information

  20. How adaptive learning affects evolution: reviewing theory on the Baldwin effect

    NARCIS (Netherlands)

    Sznajder, B.; Sabelis, M.W.; Egas, M.

    2012-01-01

    We review models of the Baldwin effect, i.e., the hypothesis that adaptive learning (i.e., learning to improve fitness) accelerates genetic evolution of the phenotype. Numerous theoretical studies scrutinized the hypothesis that a non-evolving ability of adaptive learning accelerates evolution of

  1. Light adaptation and the evolution of vertebrate photoreceptors.

    Science.gov (United States)

    Morshedian, Ala; Fain, Gordon L

    2017-07-15

    Lamprey are cyclostomes, a group of vertebrates that diverged from lines leading to jawed vertebrates (including mammals) in the late Cambrian, 500 million years ago. It may therefore be possible to infer properties of photoreceptors in early vertebrate progenitors by comparing lamprey to other vertebrates. We show that lamprey rods and cones respond to light much like rods and cones in amphibians and mammals. They operate over a similar range of light intensities and adapt to backgrounds and bleaches nearly identically. These correspondences are pervasive and detailed; they argue for the presence of rods and cones very early in the evolution of vertebrates with properties much like those of rods and cones in existing vertebrate species. The earliest vertebrates were agnathans - fish-like organisms without jaws, which first appeared near the end of the Cambrian radiation. One group of agnathans became cyclostomes, which include lamprey and hagfish. Other agnathans gave rise to jawed vertebrates or gnathostomes, the group including all other existing vertebrate species. Because cyclostomes diverged from other vertebrates 500 million years ago, it may be possible to infer some of the properties of the retina of early vertebrate progenitors by comparing lamprey to other vertebrates. We have previously shown that rods and cones in lamprey respond to light much like photoreceptors in other vertebrates and have a similar sensitivity. We now show that these affinities are even closer. Both rods and cones adapt to background light and to bleaches in a manner almost identical to other vertebrate photoreceptors. The operating range in darkness is nearly the same in lamprey and in amphibian or mammalian rods and cones; moreover background light shifts response-intensity curves downward and to the right over a similar range of ambient intensities. Rods show increment saturation at about the same intensity as mammalian rods, and cones never saturate. Bleaches decrease

  2. Automatic Clustering Using FSDE-Forced Strategy Differential Evolution

    Science.gov (United States)

    Yasid, A.

    2018-01-01

    Clustering analysis is important in datamining for unsupervised data, cause no adequate prior knowledge. One of the important tasks is defining the number of clusters without user involvement that is known as automatic clustering. This study intends on acquiring cluster number automatically utilizing forced strategy differential evolution (AC-FSDE). Two mutation parameters, namely: constant parameter and variable parameter are employed to boost differential evolution performance. Four well-known benchmark datasets were used to evaluate the algorithm. Moreover, the result is compared with other state of the art automatic clustering methods. The experiment results evidence that AC-FSDE is better or competitive with other existing automatic clustering algorithm.

  3. Evidence of correlated evolution and adaptive differentiation of stem and leaf functional traits in the herbaceous genus, Helianthus.

    Science.gov (United States)

    Pilote, Alex J; Donovan, Lisa A

    2016-12-01

    Patterns of plant stem traits are expected to align with a "fast-slow" plant economic spectrum across taxa. Although broad patterns support such tradeoffs in field studies, tests of hypothesized correlated trait evolution and adaptive differentiation are more robust when taxa relatedness and environment are taken into consideration. Here we test for correlated evolution of stem and leaf traits and their adaptive differentiation across environments in the herbaceous genus, Helianthus. Stem and leaf traits of 14 species of Helianthus (28 populations) were assessed in a common garden greenhouse study. Phylogenetically independent contrasts were used to test for evidence of correlated evolution of stem hydraulic and biomechanical properties, correlated evolution of stem and leaf traits, and adaptive differentiation associated with source habitat environments. Among stem traits, there was evidence for correlated evolution of some hydraulic and biomechanical properties, supporting an expected tradeoff between stem theoretical hydraulic efficiency and resistance to bending stress. Population differentiation for suites of stem and leaf traits was found to be consistent with a "fast-slow" resource-use axis for traits related to water transport and use. Associations of population traits with source habitat characteristics supported repeated evolution of a resource-acquisitive "drought-escape" strategy in arid environments. This study provides evidence of correlated evolution of stem and leaf traits consistent with the fast-slow spectrum of trait combinations related to water transport and use along the stem-to-leaf pathway. Correlations of traits with source habitat characteristics further indicate that the correlated evolution is associated, at least in part, with adaptive differentiation of Helianthus populations among native habitats differing in climate. © 2016 Botanical Society of America.

  4. An adaptable navigation strategy for Virtual Microscopy from mobile platforms.

    Science.gov (United States)

    Corredor, Germán; Romero, Eduardo; Iregui, Marcela

    2015-04-01

    Real integration of Virtual Microscopy with the pathologist service workflow requires the design of adaptable strategies for any hospital service to interact with a set of Whole Slide Images. Nowadays, mobile devices have the actual potential of supporting an online pervasive network of specialists working together. However, such devices are still very limited. This article introduces a novel highly adaptable strategy for streaming and visualizing WSI from mobile devices. The presented approach effectively exploits and extends the granularity of the JPEG2000 standard and integrates it with different strategies to achieve a lossless, loosely-coupled, decoder and platform independent implementation, adaptable to any interaction model. The performance was evaluated by two expert pathologists interacting with a set of 20 virtual slides. The method efficiently uses the available device resources: the memory usage did not exceed a 7% of the device capacity while the decoding times were smaller than the 200 ms per Region of Interest, i.e., a window of 256×256 pixels. This model is easily adaptable to other medical imaging scenarios. Copyright © 2015 Elsevier Inc. All rights reserved.

  5. An unsupervised adaptive strategy for constructing probabilistic roadmaps

    KAUST Repository

    Tapia, L.

    2009-05-01

    Since planning environments are complex and no single planner exists that is best for all problems, much work has been done to explore methods for selecting where and when to apply particular planners. However, these two questions have been difficult to answer, even when adaptive methods meant to facilitate a solution are applied. For example, adaptive solutions such as setting learning rates, hand-classifying spaces, and defining parameters for a library of planners have all been proposed. We demonstrate a strategy based on unsupervised learning methods that makes adaptive planning more practical. The unsupervised strategies require less user intervention, model the topology of the problem in a reasonable and efficient manner, can adapt the sampler depending on characteristics of the problem, and can easily accept new samplers as they become available. Through a series of experiments, we demonstrate that in a wide variety of environments, the regions automatically identified by our technique represent the planning space well both in number and placement.We also show that our technique has little overhead and that it out-performs two existing adaptive methods in all complex cases studied.© 2009 IEEE.

  6. Adaptive local routing strategy on a scale-free network

    International Nuclear Information System (INIS)

    Feng, Liu; Han, Zhao; Ming, Li; Yan-Bo, Zhu; Feng-Yuan, Ren

    2010-01-01

    Due to the heterogeneity of the structure on a scale-free network, making the betweennesses of all nodes become homogeneous by reassigning the weights of nodes or edges is very difficult. In order to take advantage of the important effect of high degree nodes on the shortest path communication and preferentially deliver packets by them to increase the probability to destination, an adaptive local routing strategy on a scale-free network is proposed, in which the node adjusts the forwarding probability with the dynamical traffic load (packet queue length) and the degree distribution of neighbouring nodes. The critical queue length of a node is set to be proportional to its degree, and the node with high degree has a larger critical queue length to store and forward more packets. When the queue length of a high degree node is shorter than its critical queue length, it has a higher probability to forward packets. After higher degree nodes are saturated (whose queue lengths are longer than their critical queue lengths), more packets will be delivered by the lower degree nodes around them. The adaptive local routing strategy increases the probability of a packet finding its destination quickly, and improves the transmission capacity on the scale-free network by reducing routing hops. The simulation results show that the transmission capacity of the adaptive local routing strategy is larger than that of three previous local routing strategies. (general)

  7. The population ecology of contemporary adaptations: what empirical studies reveal about the conditions that promote adaptive evolution.

    Science.gov (United States)

    Reznick, D N; Ghalambor, C K

    2001-01-01

    Under what conditions might organisms be capable of rapid adaptive evolution? We reviewed published studies documenting contemporary adaptations in natural populations and looked for general patterns in the population ecological causes. We found that studies of contemporary adaptation fall into two general settings: (1) colonization of new environments that established newly adapted populations, and (2) local adaptations within the context of a heterogeneous environments and metapopulation structure. Local ecological processes associated with colonizations and introductions included exposure to: (1) a novel host or food resource; (2) a new biophysical environment; (3) a new predator community; and (4) a new coexisting competitor. The new environments that were colonized often had depauperate communities, sometimes because of anthropogenic disturbance. Local adaptation in heterogeneous environments was also often associated with recent anthropogenic changes, such as insecticide and herbicide resistance, or industrial melanism. A common feature of many examples is the combination of directional selection with at least a short-term opportunity for population growth. We suggest that such opportunities for population growth may be a key factor that promotes rapid evolution, since directional selection might otherwise be expected to cause population decline and create the potential for local extinction, which is an ever-present alternative to local adaptation. We also address the large discrepancy between the rate of evolution observed in contemporary studies and the apparent rate of evolution seen in the fossil record.

  8. Evolution of Strategies for "Prisoner's Dilemma" using Genetic Algorithm

    OpenAIRE

    Heinz, Jan

    2010-01-01

    The subject of this thesis is the software application "Prisoner's Dilemma". The program creates a population of players of "Prisoner's Dilemma", has them play against each other, and - based on their results - performs an evolution of their strategies by means of a genetic algorithm (selection, mutation, and crossover). The program was written in Microsoft Visual Studio, in the C++ programming language, and its interface makes use of the .NET Framework. The thesis includes examples of strate...

  9. Transitions in optimal adaptive strategies for populations in fluctuating environments

    Science.gov (United States)

    Mayer, Andreas; Mora, Thierry; Rivoire, Olivier; Walczak, Aleksandra M.

    2017-09-01

    Biological populations are subject to fluctuating environmental conditions. Different adaptive strategies can allow them to cope with these fluctuations: specialization to one particular environmental condition, adoption of a generalist phenotype that compromises between conditions, or population-wise diversification (bet hedging). Which strategy provides the largest selective advantage in the long run depends on the range of accessible phenotypes and the statistics of the environmental fluctuations. Here, we analyze this problem in a simple mathematical model of population growth. First, we review and extend a graphical method to identify the nature of the optimal strategy when the environmental fluctuations are uncorrelated. Temporal correlations in environmental fluctuations open up new strategies that rely on memory but are mathematically challenging to study: We present analytical results to address this challenge. We illustrate our general approach by analyzing optimal adaptive strategies in the presence of trade-offs that constrain the range of accessible phenotypes. Our results extend several previous studies and have applications to a variety of biological phenomena, from antibiotic resistance in bacteria to immune responses in vertebrates.

  10. Strategies to intervene on causal systems are adaptively selected.

    Science.gov (United States)

    Coenen, Anna; Rehder, Bob; Gureckis, Todd M

    2015-06-01

    How do people choose interventions to learn about causal systems? Here, we considered two possibilities. First, we test an information sampling model, information gain, which values interventions that can discriminate between a learner's hypotheses (i.e. possible causal structures). We compare this discriminatory model to a positive testing strategy that instead aims to confirm individual hypotheses. Experiment 1 shows that individual behavior is described best by a mixture of these two alternatives. In Experiment 2 we find that people are able to adaptively alter their behavior and adopt the discriminatory model more often after experiencing that the confirmatory strategy leads to a subjective performance decrement. In Experiment 3, time pressure leads to the opposite effect of inducing a change towards the simpler positive testing strategy. These findings suggest that there is no single strategy that describes how intervention decisions are made. Instead, people select strategies in an adaptive fashion that trades off their expected performance and cognitive effort. Copyright © 2015 Elsevier Inc. All rights reserved.

  11. Suppressing traffic-driven epidemic spreading by adaptive routing strategy

    International Nuclear Information System (INIS)

    Yang, Han-Xin; Wang, Zhen

    2016-01-01

    The design of routing strategies for traffic-driven epidemic spreading has received increasing attention in recent years. In this paper, we propose an adaptive routing strategy that incorporates topological distance with local epidemic information through a tunable parameter h. In the case where the traffic is free of congestion, there exists an optimal value of routing parameter h, leading to the maximal epidemic threshold. This means that epidemic spreading can be more effectively controlled by adaptive routing, compared to that of the static shortest path routing scheme. Besides, we find that the optimal value of h can greatly relieve the traffic congestion in the case of finite node-delivering capacity. We expect our work to provide new insights into the effects of dynamic routings on traffic-driven epidemic spreading.

  12. Small Firm Adaptive Capability, Competitive Strategy and Performance Outcomes: Competing Mediation vs Moderation Perspectives

    OpenAIRE

    Chryssochoidis, George; Dousios, Dimitrios; Tzokas, Nikolaos

    2016-01-01

    In small firms, adaptive capability exercises a handling grip on competitive strategy for superior performance primarily acting as a mediator and may offset, through attenuation, the adverse impact of limited resources. Besides exercising a handling grip on competitive strategy adaptive capability is more important than competitive strategy per se for superior performance. Adaptive capability simultaneously undertakes additional secondary roles reinforcing innovation competitive strategy for ...

  13. Strategy Dynamics through a Demand-Based Lens: The Evolution of Market Boundaries, Resource Rents and Competitive Positions

    OpenAIRE

    Adner, Ron; Zemsky, Peter

    2003-01-01

    We develop a novel approach to the dynamics of business strategy that is grounded in an explicit treatment of consumer choice when technologies improve over time. We address the evolution of market boundaries, resource rents and competitive positions by adapting models of competition with differentiated products. Our model is consistent with the central strategy assertion that competitive interactions are governed by superior value creation and competitive advantage. More importantly, it show...

  14. A Climate Change Adaptation Strategy for Management of ...

    Science.gov (United States)

    Sea level rise is causing shoreline erosion, increased coastal flooding, and marsh vulnerability to the impact of storms. Coastal marshes provide flood abatement, carbon and nutrient sequestration, water quality maintenance, and habitat for fish, shellfish, and wildlife, including species of concern, such as the saltmarsh sparrow (Ammodramus caudacutus). We present a climate change adaptation strategy (CCAS) adopted by scientific, management, and policy stakeholders for managing coastal marshes and enhancing system resiliency. A common adaptive management approach previously used for restoration projects was modified to identify climate-related vulnerabilities and plan climate change adaptive actions. As an example of implementation of the CCAS, we describe the stakeholder plans and management actions the US Fish and Wildlife Service and partners developed to build coastal resiliency in the Narrow River Estuary, RI, in the aftermath of Superstorm Sandy. When possible, an experimental BACI (before-after, control-impact) design, described as pre- and post-sampling at the impact site and one or more control sites, was incorporated into the climate change adaptation and implementation plans. Specific climate change adaptive actions and monitoring plans are described and include shoreline stabilization, restoring marsh drainage, increasing marsh elevation, and enabling upland marsh migration. The CCAS provides a framework and methodology for successfully managing coa

  15. Nutrient-dependent/pheromone-controlled adaptive evolution: a model

    Directory of Open Access Journals (Sweden)

    James Vaughn Kohl

    2013-06-01

    Full Text Available Background: The prenatal migration of gonadotropin-releasing hormone (GnRH neurosecretory neurons allows nutrients and human pheromones to alter GnRH pulsatility, which modulates the concurrent maturation of the neuroendocrine, reproductive, and central nervous systems, thus influencing the development of ingestive behavior, reproductive sexual behavior, and other behaviors. Methods: This model details how chemical ecology drives adaptive evolution via: (1 ecological niche construction, (2 social niche construction, (3 neurogenic niche construction, and (4 socio-cognitive niche construction. This model exemplifies the epigenetic effects of olfactory/pheromonal conditioning, which alters genetically predisposed, nutrient-dependent, hormone-driven mammalian behavior and choices for pheromones that control reproduction via their effects on luteinizing hormone (LH and systems biology. Results: Nutrients are metabolized to pheromones that condition behavior in the same way that food odors condition behavior associated with food preferences. The epigenetic effects of olfactory/pheromonal input calibrate and standardize molecular mechanisms for genetically predisposed receptor-mediated changes in intracellular signaling and stochastic gene expression in GnRH neurosecretory neurons of brain tissue. For example, glucose and pheromones alter the hypothalamic secretion of GnRH and LH. A form of GnRH associated with sexual orientation in yeasts links control of the feedback loops and developmental processes required for nutrient acquisition, movement, reproduction, and the diversification of species from microbes to man. Conclusion: An environmental drive evolved from that of nutrient ingestion in unicellular organisms to that of pheromone-controlled socialization in insects. In mammals, food odors and pheromones cause changes in hormones such as LH, which has developmental affects on pheromone-controlled sexual behavior in nutrient-dependent reproductively

  16. Evolution of cooperation through adaptive interaction in a spatial prisoner's dilemma game

    Science.gov (United States)

    Pan, Qiuhui; Liu, Xuesong; Bao, Honglin; Su, Yu; He, Mingfeng

    2018-02-01

    In this paper, we study the effect of adaptive interaction on the evolution of cooperation in a spatial prisoner's dilemma game. The connections of players are co-evolutionary with cooperation; whether adjacent players can play the prisoner's dilemma game is associated with the strategies they took in the preceding round. If a player defected in the preceding round, his neighbors will refuse to play the prisoner's dilemma game with him in accordance with a certain probability distribution. We use the disconnecting strength to represent this probability. We discuss the evolution of cooperation with different values of temptation to defect, sucker's payoff and disconnecting strength. The simulation results show that cooperation can be significantly enhanced through increasing the value of the disconnecting strength. In addition, the increase in disconnecting strength can improve the cooperators' ability to resist the increase in temptation and the decrease in reward. We study the parameter ranges for three different evolutionary results: cooperators extinction, defectors extinction, cooperator and defector co-existence. Meanwhile, we recruited volunteers and designed a human behavioral experiment to verify the theoretical simulation results. The punishment of disconnection has a positive effect on cooperation. A higher disconnecting strength will enhance cooperation more significantly. Our research findings reveal some significant insights into efficient mechanisms of the evolution of cooperation.

  17. Battery parameterisation based on differential evolution via a boundary evolution strategy

    DEFF Research Database (Denmark)

    Yang, Guangya

    2013-01-01

    the advances of evolutionary algorithms (EAs). Differential evolution (DE) is selected and modified to parameterise an equivalent circuit model of lithium-ion batteries. A boundary evolution strategy (BES) is developed and incorporated into the DE to update the parameter boundaries during the parameterisation......, as the equivalent circuit model is an abstract map of the battery electric characteristics, the determination of the possible ranges of parameters can be a challenging task. In this paper, an efficient yet easy to implement method is proposed to parameterise the equivalent circuit model of batteries utilising...

  18. Risk evaluation mitigation strategies: the evolution of risk management policy.

    Science.gov (United States)

    Hollingsworth, Kristen; Toscani, Michael

    2013-04-01

    The United States Food and Drug Administration (FDA) has the primary regulatory responsibility to ensure that medications are safe and effective both prior to drug approval and while the medication is being actively marketed by manufacturers. The responsibility for safe medications prior to marketing was signed into law in 1938 under the Federal Food, Drug, and Cosmetic Act; however, a significant risk management evolution has taken place since 1938. Additional federal rules, entitled the Food and Drug Administration Amendments Act, were established in 2007 and extended the government's oversight through the addition of a Risk Evaluation and Mitigation Strategy (REMS) for certain drugs. REMS is a mandated strategy to manage a known or potentially serious risk associated with a medication or biological product. Reasons for this extension of oversight were driven primarily by the FDA's movement to ensure that patients and providers are better informed of drug therapies and their specific benefits and risks prior to initiation. This article provides an historical perspective of the evolution of medication risk management policy and includes a review of REMS programs, an assessment of the positive and negative aspects of REMS, and provides suggestions for planning and measuring outcomes. In particular, this publication presents an overview of the evolution of the REMS program and its implications.

  19. Implications of prion adaptation and evolution paradigm for human neurodegenerative diseases.

    Science.gov (United States)

    Kabir, M Enamul; Safar, Jiri G

    2014-01-01

    There is a growing body of evidence indicating that number of human neurodegenerative diseases, including Alzheimer disease, Parkinson disease, fronto-temporal dementias, and amyotrophic lateral sclerosis, propagate in the brain via prion-like intercellular induction of protein misfolding. Prions cause lethal neurodegenerative diseases in humans, the most prevalent being sporadic Creutzfeldt-Jakob disease (sCJD); they self-replicate and spread by converting the cellular form of prion protein (PrP(C)) to a misfolded pathogenic conformer (PrP(Sc)). The extensive phenotypic heterogeneity of human prion diseases is determined by polymorphisms in the prion protein gene, and by prion strain-specific conformation of PrP(Sc). Remarkably, even though informative nucleic acid is absent, prions may undergo rapid adaptation and evolution in cloned cells and upon crossing the species barrier. In the course of our investigation of this process, we isolated distinct populations of PrP(Sc) particles that frequently co-exist in sCJD. The human prion particles replicate independently and undergo competitive selection of those with lower initial conformational stability. Exposed to mutant substrate, the winning PrP(Sc) conformers are subject to further evolution by natural selection of the subpopulation with the highest replication rate due to the lowest stability. Thus, the evolution and adaptation of human prions is enabled by a dynamic collection of distinct populations of particles, whose evolution is governed by the selection of progressively less stable, faster replicating PrP(Sc) conformers. This fundamental biological mechanism may explain the drug resistance that some prions gained after exposure to compounds targeting PrP(Sc). Whether the phenotypic heterogeneity of other neurodegenerative diseases caused by protein misfolding is determined by the spectrum of misfolded conformers (strains) remains to be established. However, the prospect that these conformers may evolve and

  20. Adaptation Strategies and Resilience to Climate Change of Historic Dwellings

    Directory of Open Access Journals (Sweden)

    Carlos Rubio-Bellido

    2015-03-01

    Full Text Available Historic city centres have a large amount of dwellings in Europe, which were built to provide a comfortable shelter with the absence of mechanical means. The knowledge of climate responsive design strategies can play a significant role in reducing the energy demand of extant buildings, paving the way for its sustainable development in the face of the rising threat to its occupants of climate change. The residential architecture, developed, in most cases, in dense urban centres, was built using both available materials and traditional and academic construction technologies. This paper thoroughly investigates the extant urban conglomerate in Cádiz and analyses, in a qualitative and quantitative manner, which bioclimatic design strategies were applied and the city’s adaptation for future climate scenarios. The results indicate that historic housing in Cádiz is creatively adapted to the local natural conditions by means of a combination of climate responsive strategies, and there is significant scope for improvement in the ongoing response to global warming.

  1. Adapting qualitative research strategies to technology savvy adolescents.

    Science.gov (United States)

    Mason, Deanna Marie; Ide, Bette

    2014-05-01

    To adapt research strategies involving adolescents in a grounded theory qualitative research study by conducting email rather than face-to-face interviews. Adolescent culture relies heavily on text-based communication and teens prefer interactions mediated through technology. Traditional qualitative research strategies need to be rethought when working with adolescents. Adapting interviewing strategies to electronic environments is timely and relevant for researching adolescents. Twenty three adolescents (aged 16-21) were interviewed by email. A letter of invitation was distributed. Potential participants emailed the researcher to convey interest in participating. If the inclusion criteria were met, email interviews were initiated. Participants controlled the interviews through their rate of response to interview questions. A grounded theory methodology was employed. Initial contact with participants reiterated confidentiality and the ability to withdraw from the study at any time. Interviews began with the collection of demographic information and a broad opening based on a semi-structured interview guide. All data were permissible, including text, photos, music, videos or outside media, for example YouTube. The participant was allowed to give direction to the interview after initial questions were posed. Email interviews continued until saturation was reached in the data. Participants were enthusiastic about email interviewing. Attrition did not occur. Email interviewing gave participants more control over the research, decreased power differentials between the adolescent and researcher, allowed the study to be adapted to cultural, linguistic and developmental needs, and maintained confidentiality. As participants said that email communication was slow and they preferred instant messaging, replication in faster-paced media is recommended. Repetition in face-to-face settings is warranted to evaluate how technology may have influenced the findings. Implications for

  2. Adaptive evolution of relish, a Drosophila NF-kappaB/IkappaB protein.

    OpenAIRE

    Begun, D J; Whitley, P

    2000-01-01

    NF-kappaB and IkappaB proteins have central roles in regulation of inflammation and innate immunity in mammals. Homologues of these proteins also play an important role in regulation of the Drosophila immune response. Here we present a molecular population genetic analysis of Relish, a Drosophila NF-kappaB/IkappaB protein, in Drosophila simulans and D. melanogaster. We find strong evidence for adaptive protein evolution in D. simulans, but not in D. melanogaster. The adaptive evolution appear...

  3. Segmented bimorph mirrors for adaptive optics: morphing strategy.

    Science.gov (United States)

    Bastaits, Renaud; Alaluf, David; Belloni, Edoardo; Rodrigues, Gonçalo; Preumont, André

    2014-08-01

    This paper discusses the concept of a light weight segmented bimorph mirror for adaptive optics. It focuses on the morphing strategy and addresses the ill-conditioning of the Jacobian of the segments, which are partly outside the optical pupil. Two options are discussed, one based on truncating the singular values and one called damped least squares, which minimizes a combined measure of the sensor error and the voltage vector. A comparison of various configurations of segmented mirrors was conducted; it is shown that segmentation sharply increases the natural frequency of the system with limited deterioration of the image quality.

  4. Intermediate Collaborative Adaptive Management Strategies Build Stakeholder Capacity

    Directory of Open Access Journals (Sweden)

    Martha C. Monroe

    2013-06-01

    Full Text Available Efforts to implement collaborative adaptive management (CAM often suffer from challenges, such as an unwillingness of managers to share power, unresolved conflicts between stakeholders, and lack of capacity among stakeholders. Some aspects considered essential to CAM, e.g., trust and stakeholder capacity, may be more usefully viewed as goals for intermediate strategies rather than a set of initial conditions. From this perspective, intermediate steps that focus on social learning and building experience could overcome commonly cited barriers to CAM. An exploration of Springs Basin Working Groups, organized around major clusters of freshwater springs in north Florida, provides a case study of how these intermediate steps enable participants to become more reasonable and engaged. This strategy may be easily implemented by agencies beginning a CAM process.

  5. Adaptive Active Noise Suppression Using Multiple Model Switching Strategy

    Directory of Open Access Journals (Sweden)

    Quanzhen Huang

    2017-01-01

    Full Text Available Active noise suppression for applications where the system response varies with time is a difficult problem. The computation burden for the existing control algorithms with online identification is heavy and easy to cause control system instability. A new active noise control algorithm is proposed in this paper by employing multiple model switching strategy for secondary path varying. The computation is significantly reduced. Firstly, a noise control system modeling method is proposed for duct-like applications. Then a multiple model adaptive control algorithm is proposed with a new multiple model switching strategy based on filter-u least mean square (FULMS algorithm. Finally, the proposed algorithm was implemented on Texas Instruments digital signal processor (DSP TMS320F28335 and real time experiments were done to test the proposed algorithm and FULMS algorithm with online identification. Experimental verification tests show that the proposed algorithm is effective with good noise suppression performance.

  6. The evolution of intellectual property strategy in innovation ecosystems

    DEFF Research Database (Denmark)

    Holgersson, Marcus; Granstrand, Ove; Bogers, Marcel

    2017-01-01

    In this article, we attempt to extend and nuance the debate on intellectual property (IP) strategy, appropriation, and open innovation in dynamic and systemic innovation contexts. We present the case of four generations of mobile telecommunications systems (covering the period 1980-2015), and des......In this article, we attempt to extend and nuance the debate on intellectual property (IP) strategy, appropriation, and open innovation in dynamic and systemic innovation contexts. We present the case of four generations of mobile telecommunications systems (covering the period 1980......-2015), and describe and analyze the co-evolution of strategic IP management and innovation ecosystems. Throughout this development, technologies and technological relationships were governed with different and shifting degrees of formality. Simultaneously, firms differentiated technology accessibility across actors...

  7. The ongoing adaptive evolution of ASPM and Microcephalin is not explained by increased intelligence.

    NARCIS (Netherlands)

    Mekel-Bobrov, N.; Posthuma, D.; Gilbert, S.L.; Lind, P.; Gosso, M.F.; Luciano, M.; Harris, S.E.; Bates, T.C.; Polderman, T.J.C.; Whalley, L.J.; Fox, H.; Starr, J.M.; Evans, P.D.; Montgomery, GW; Fernandes, C.; Heutink, P.; Martin, N.G.; Boomsma, D.I.; Deary, I.J.; Wright, M.J.; de Geus, E.J.C.; Lahn, B.T.

    2007-01-01

    Recent studies have made great strides towards identifying putative genetic events underlying the evolution of the human brain and its emergent cognitive capacities. One of the most intriguing findings is the recurrent identification of adaptive evolution in genes associated with primary

  8. Adaptive sampling strategies with high-throughput molecular dynamics

    Science.gov (United States)

    Clementi, Cecilia

    Despite recent significant hardware and software developments, the complete thermodynamic and kinetic characterization of large macromolecular complexes by molecular simulations still presents significant challenges. The high dimensionality of these systems and the complexity of the associated potential energy surfaces (creating multiple metastable regions connected by high free energy barriers) does not usually allow to adequately sample the relevant regions of their configurational space by means of a single, long Molecular Dynamics (MD) trajectory. Several different approaches have been proposed to tackle this sampling problem. We focus on the development of ensemble simulation strategies, where data from a large number of weakly coupled simulations are integrated to explore the configurational landscape of a complex system more efficiently. Ensemble methods are of increasing interest as the hardware roadmap is now mostly based on increasing core counts, rather than clock speeds. The main challenge in the development of an ensemble approach for efficient sampling is in the design of strategies to adaptively distribute the trajectories over the relevant regions of the systems' configurational space, without using any a priori information on the system global properties. We will discuss the definition of smart adaptive sampling approaches that can redirect computational resources towards unexplored yet relevant regions. Our approaches are based on new developments in dimensionality reduction for high dimensional dynamical systems, and optimal redistribution of resources. NSF CHE-1152344, NSF CHE-1265929, Welch Foundation C-1570.

  9. Climate Variability and Household Adaptation Strategies in Southern Ethiopia

    Directory of Open Access Journals (Sweden)

    Wassie Berhanu

    2015-05-01

    Full Text Available This paper examines the determinants and implied economic impacts of climate change adaptation strategies in the context of traditional pastoralism. It is based on econometric analysis of survey data generated from household level interviews in southern Ethiopian rangelands. Pastoralists’ perception of climate change in the region is found to be very consistent with the actually recorded trends of increased temperature and the evident secular declines in precipitation. Not only long-term declines, trends in the region’s rainfall also appear to have taken a shift towards the direction of more unpredictability. Pastoralist adaptation response strategies broadly involve adjustments in pastoral practices and shifts to non-pastoral livelihoods. Results of the estimated models confirm that pastoral mobility is still quite essential in the present context of climate-induced household vulnerabilities. Increased mobility and diversification of pastoral herd portfolios in favor of a drought-tolerant species (camel are found to be positively associated with pastoral household net income. A policy stance that ignores the detrimental impacts of the currently pervasive private rangeland enclosures or intends to hasten pastoralist sedentarization in the area is simply untenable in the present context of climate-induced risks and pastoral livelihood vulnerability.

  10. Immune genes undergo more adaptive evolution than non-immune system genes in Daphnia pulex

    Directory of Open Access Journals (Sweden)

    McTaggart Seanna J

    2012-05-01

    Full Text Available Abstract Background Understanding which parts of the genome have been most influenced by adaptive evolution remains an unsolved puzzle. Some evidence suggests that selection has the greatest impact on regions of the genome that interact with other evolving genomes, including loci that are involved in host-parasite co-evolutionary processes. In this study, we used a population genetic approach to test this hypothesis by comparing DNA sequences of 30 putative immune system genes in the crustacean Daphnia pulex with 24 non-immune system genes. Results In support of the hypothesis, results from a multilocus extension of the McDonald-Kreitman (MK test indicate that immune system genes as a class have experienced more adaptive evolution than non-immune system genes. However, not all immune system genes show evidence of adaptive evolution. Additionally, we apply single locus MK tests and calculate population genetic parameters at all loci in order to characterize the mode of selection (directional versus balancing in the genes that show the greatest deviation from neutral evolution. Conclusions Our data are consistent with the hypothesis that immune system genes undergo more adaptive evolution than non-immune system genes, possibly as a result of host-parasite arms races. The results of these analyses highlight several candidate loci undergoing adaptive evolution that could be targeted in future studies.

  11. Advance strategy for climate change adaptation and mitigation in cities

    Science.gov (United States)

    Varquez, A. C. G.; Kanda, M.; Darmanto, N. S.; Sueishi, T.; Kawano, N.

    2017-12-01

    An on-going 5-yr project financially supported by the Ministry of Environment, Japan, has been carried out to specifically address the issue of prescribing appropriate adaptation and mitigation measures to climate change in cities. Entitled "Case Study on Mitigation and Local Adaptation to Climate Change in an Asian Megacity, Jakarta", the project's relevant objectives is to develop a research framework that can consider both urbanization and climate change with the main advantage of being readily implementable for all cities around the world. The test location is the benchmark city, Jakarta, Indonesia, with the end focus of evaluating the benefits of various mitigation and adaptation strategies in Jakarta and other megacities. The framework was designed to improve representation of urban areas when conducting climate change investigations in cities; and to be able to quantify separately the impacts of urbanization and climate change to all cities globally. It is comprised of a sophisticated, top-down, multi-downscaling approach utilizing a regional model (numerical weather model) and a microscale model (energy balance model and CFD model), with global circulation models (GCM) as input. The models, except the GCM, were configured to reasonably consider land cover, urban morphology, and anthropogenic heating (AH). Equally as important, methodologies that can collect and estimate global distribution of urban parametric and AH datasets are continually being developed. Urban growth models, climate scenario matrices that match representative concentration pathways with shared socio-economic pathways, present distribution of socio-demographic indicators such as population and GDP, existing GIS datasets of urban parameters, are utilized. From these tools, future urbanization (urban morphological parameters and AH) can be introduced into the models. Sensitivity using various combinations of GCM and urbanization can be conducted. Furthermore, since the models utilize

  12. The evolution of unconditional strategies via the 'multiplier effect'.

    Science.gov (United States)

    McNamara, John M; Dall, Sasha R X

    2011-03-01

    Ostensibly, it makes sense in a changeable world to condition behaviour and development on information when it is available. Nevertheless, unconditional behavioural and life history strategies are widespread. Here, we show how intergenerational effects can limit the evolutionary value of responding to reliable environmental cues, and thus favour the evolutionary persistence of otherwise paradoxical unconditional strategies. While cue-ignoring genotypes do poorly in the wrong environments, in the right environment they will leave many copies of themselves, which will themselves leave many copies, and so on, leading genotypes to accumulate in habitats in which they do well. We call this 'The Multiplier Effect'. We explore the consequences of the multiplier effect by focussing on the ecologically important phenomenon of natal philopatry. We model the environment as a large number of temporally varying breeding sites connected by natal dispersal between sites. Our aim is to identify which aspects of an environment promote the multiplier effect. We show, if sites remain connected through some background level of 'accidental' dispersal, unconditional natal philopatry can evolve even when there is density dependence (with its accompanying kin competition effects), and cues that are only mildly erroneous. Thus, the multiplier effect may underpin the evolution and maintenance of unconditional strategies such as natal philopatry in many biological systems. © 2011 Blackwell Publishing Ltd/CNRS.

  13. Time in Redox Adaptation Processes: From Evolution to Hormesis

    Directory of Open Access Journals (Sweden)

    Mireille M. J. P. E. Sthijns

    2016-09-01

    Full Text Available Life on Earth has to adapt to the ever changing environment. For example, due to introduction of oxygen in the atmosphere, an antioxidant network evolved to cope with the exposure to oxygen. The adaptive mechanisms of the antioxidant network, specifically the glutathione (GSH system, are reviewed with a special focus on the time. The quickest adaptive response to oxidative stress is direct enzyme modification, increasing the GSH levels or activating the GSH-dependent protective enzymes. After several hours, a hormetic response is seen at the transcriptional level by up-regulating Nrf2-mediated expression of enzymes involved in GSH synthesis. In the long run, adaptations occur at the epigenetic and genomic level; for example, the ability to synthesize GSH by phototrophic bacteria. Apparently, in an adaptive hormetic response not only the dose or the compound, but also time, should be considered. This is essential for targeted interventions aimed to prevent diseases by successfully coping with changes in the environment e.g., oxidative stress.

  14. Adaptive laboratory evolution of ethanologenic Zymomonas mobilis strain tolerant to furfural and acetic acid inhibitors.

    Science.gov (United States)

    Shui, Zong-Xia; Qin, Han; Wu, Bo; Ruan, Zhi-yong; Wang, Lu-shang; Tan, Fu-Rong; Wang, Jing-Li; Tang, Xiao-Yu; Dai, Li-Chun; Hu, Guo-Quan; He, Ming-Xiong

    2015-07-01

    Furfural and acetic acid from lignocellulosic hydrolysates are the prevalent inhibitors to Zymomonas mobilis during cellulosic ethanol production. Developing a strain tolerant to furfural or acetic acid inhibitors is difficul by using rational engineering strategies due to poor understanding of their underlying molecular mechanisms. In this study, strategy of adaptive laboratory evolution (ALE) was used for development of a furfural and acetic acid-tolerant strain. After three round evolution, four evolved mutants (ZMA7-2, ZMA7-3, ZMF3-2, and ZMF3-3) that showed higher growth capacity were successfully obtained via ALE method. Based on the results of profiling of cell growth, glucose utilization, ethanol yield, and activity of key enzymes, two desired strains, ZMA7-2 and ZMF3-3, were achieved, which showed higher tolerance under 7 g/l acetic acid and 3 g/l furfural stress condition. Especially, it is the first report of Z. mobilis strain that could tolerate higher furfural. The best strain, Z. mobilis ZMF3-3, has showed 94.84% theoretical ethanol yield under 3-g/l furfural stress condition, and the theoretical ethanol yield of ZM4 is only 9.89%. Our study also demonstrated that ALE method might also be used as a powerful metabolic engineering tool for metabolic engineering in Z. mobilis. Furthermore, the two best strains could be used as novel host for further metabolic engineering in cellulosic ethanol or future biorefinery. Importantly, the two strains may also be used as novel-tolerant model organisms for the genetic mechanism on the "omics" level, which will provide some useful information for inverse metabolic engineering.

  15. Evidence for adaptive evolution of low-temperature stress response genes in a Pooideae grass ancestor

    DEFF Research Database (Denmark)

    Vigeland, Magnus D; Spannagl, Manuel; Asp, Torben

    2013-01-01

    Adaptation to temperate environments is common in the grass subfamily Pooideae, suggesting an ancestral origin of cold climate adaptation. Here, we investigated substitution rates of genes involved in low-temperature-induced (LTI) stress responses to test the hypothesis that adaptive molecular...... evolution of LTI pathway genes was important for Pooideae evolution. Substitution rates and signatures of positive selection were analyzed using 4330 gene trees including three warm climate-adapted species (maize (Zea mays), sorghum (Sorghum bicolor), and rice (Oryza sativa)) and five temperate Pooideae...... species (Brachypodium distachyon, wheat (Triticum aestivum), barley (Hordeum vulgare), Lolium perenne and Festuca pratensis). Nonsynonymous substitution rate differences between Pooideae and warm habitat-adapted species were elevated in LTI trees compared with all trees. Furthermore, signatures...

  16. The evolution of Soviet forces, strategy, and command

    International Nuclear Information System (INIS)

    Ball, D.; Bethe, H.A.; Blair, B.G.; Bracken, P.; Carter, A.B.; Dickinson, H.; Garwin, R.L.; Holloway, D.; Kendall, H.W.

    1988-01-01

    This paper reports on the evolution of Soviet forces, strategy and command. Soviet leaders have repeatedly emphasized that it would be tantamount to suicide to start a nuclear war. Mutual deterrence, however, does not make nuclear was impossible. The danger remains that a large-scale nuclear was could start inadvertently in an intense crisis, or by escalation out of a conventional war, or as an unforeseen combination of these. For these reasons crisis management has become a central issue in the United States, but the standard Soviet response to this Western interest has been to say that what is needed is crisis avoidance, not recipes for brinkmanship masquerading under another name. There is much sense in this view. Nevertheless, this demeanor does not mean that the Soviet Union has given no thought to the danger that a crisis might lead to nuclear war, only that Soviet categories for thinking about such matters differ from those employed in the United States

  17. Using 2-Opt based evolution strategy for travelling salesman problem

    Directory of Open Access Journals (Sweden)

    Kenan Karagul

    2016-03-01

    Full Text Available Harmony search algorithm that matches the (µ+1 evolution strategy, is a heuristic method simulated by the process of music improvisation. In this paper, a harmony search algorithm is directly used for the travelling salesman problem. Instead of conventional selection operators such as roulette wheel, the transformation of real number values of harmony search algorithm to order index of vertex representation and improvement of solutions are obtained by using the 2-Opt local search algorithm. Then, the obtained algorithm is tested on two different parameter groups of TSPLIB. The proposed method is compared with classical 2-Opt which randomly started at each step and best known solutions of test instances from TSPLIB. It is seen that the proposed algorithm offers valuable solutions.

  18. WE-H-207B-04: Strategies for Adaptive RT

    Energy Technology Data Exchange (ETDEWEB)

    Green, O. [Washington University School of Medicine (United States)

    2016-06-15

    In recent years, steady progress has been made towards the implementation of MRI in external beam radiation therapy for processes ranging from treatment simulation to in-room guidance. Novel procedures relying mostly on MR data are currently implemented in the clinic. This session will cover topics such as (a) commissioning and quality control of the MR in-room imagers and simulators specific to RT, (b) treatment planning requirements, constraints and challenges when dealing with various MR data, (c) quantification of organ motion with an emphasis on treatment delivery guidance, and (d) MR-driven strategies for adaptive RT workflows. The content of the session was chosen to address both educational and practical key aspects of MR guidance. Learning Objectives: Good understanding of MR testing recommended for in-room MR imaging as well as image data validation for RT chain (e.g. image transfer, filtering for consistency, spatial accuracy, manipulation for task specific); Familiarity with MR-based planning procedures: motivation, core workflow requirements, current status, challenges; Overview of the current methods for the quantification of organ motion; Discussion on approaches for adaptive treatment planning and delivery. T. Stanescu - License agreement with Modus Medical Devices to develop a phantom for the quantification of MR image system-related distortions.; T. Stanescu, N/A.

  19. WE-H-207B-04: Strategies for Adaptive RT

    International Nuclear Information System (INIS)

    Green, O.

    2016-01-01

    In recent years, steady progress has been made towards the implementation of MRI in external beam radiation therapy for processes ranging from treatment simulation to in-room guidance. Novel procedures relying mostly on MR data are currently implemented in the clinic. This session will cover topics such as (a) commissioning and quality control of the MR in-room imagers and simulators specific to RT, (b) treatment planning requirements, constraints and challenges when dealing with various MR data, (c) quantification of organ motion with an emphasis on treatment delivery guidance, and (d) MR-driven strategies for adaptive RT workflows. The content of the session was chosen to address both educational and practical key aspects of MR guidance. Learning Objectives: Good understanding of MR testing recommended for in-room MR imaging as well as image data validation for RT chain (e.g. image transfer, filtering for consistency, spatial accuracy, manipulation for task specific); Familiarity with MR-based planning procedures: motivation, core workflow requirements, current status, challenges; Overview of the current methods for the quantification of organ motion; Discussion on approaches for adaptive treatment planning and delivery. T. Stanescu - License agreement with Modus Medical Devices to develop a phantom for the quantification of MR image system-related distortions.; T. Stanescu, N/A

  20. Adapting to Adaptations: Behavioural Strategies that are Robust to Mutations and Other Organisational-Transformations

    Science.gov (United States)

    Egbert, Matthew D.; Pérez-Mercader, Juan

    2016-01-01

    Genetic mutations, infection by parasites or symbionts, and other events can transform the way that an organism’s internal state changes in response to a given environment. We use a minimalistic computational model to support an argument that by behaving “interoceptively,” i.e. responding to internal state rather than to the environment, organisms can be robust to these organisational-transformations. We suggest that the robustness of interoceptive behaviour is due, in part, to the asymmetrical relationship between an organism and its environment, where the latter more substantially influences the former than vice versa. This relationship means that interoceptive behaviour can respond to the environment, the internal state and the interaction between the two, while exteroceptive behaviour can only respond to the environment. We discuss the possibilities that (i) interoceptive behaviour may play an important role of facilitating adaptive evolution (especially in the early evolution of primitive life) and (ii) interoceptive mechanisms could prove useful in efforts to create more robust synthetic life-forms. PMID:26743579

  1. The eunuch phenomenon: adaptive evolution of genital emasculation in sexually dimorphic spiders.

    Science.gov (United States)

    Kuntner, Matjaž; Agnarsson, Ingi; Li, Daiqin

    2015-02-01

    emasculation, as well as lesser genital damage and sexual cannibalism, to be significantly associated with SSD. These behavioural and morphological traits thus likely co-evolve in spiders. Emasculation can be seen as an extreme form of genital mutilation, or even a terminal investment strategy linked to the evolution of monogyny. However, as different emasculation cases in araneoid spiders are neither homologous nor biologically identical, and may or may not serve as paternity protection, the direct link to monogyny is not clear cut. Understanding better the phylogenetic patterns of emasculation and its constituent morphologies and behaviours, a clearer picture of the intricate interplay of natural and sexual selection may arise. With the here improved evolutionary resolution of spider eunuch behaviour, we can more specifically tie the evidence from adaptive hypotheses to independent cases, and propose promising avenues for further research of spider eunuchs, and of the evolution of monogyny. © 2014 The Authors. Biological Reviews © 2014 Cambridge Philosophical Society.

  2. Adaptive evolution of sexual systems in pedunculate barnacles

    DEFF Research Database (Denmark)

    Yusa, Yoichi; Yoshikawa, Mai; Kitaura, Jun

    2012-01-01

    (androdioecy), and coexistence of dwarf males and females (dioecy). Here, we report the first phylogenetically controlled test of the hypothesis that the ultimate cause of the diverse sexual systems and presence of dwarf males in this group is limited mating opportunities for non-dwarf individuals, owing...... to mating in small groups. Within the pedunculate barnacle phylogeny, dwarf males and females have evolved repeatedly. Females are more likely to evolve in androdioecious than hermaphroditic populations, suggesting that evolution of dwarf males has preceded that of females in pedunculates. Both dwarf males...... and females are associated with a higher proportion of solitary individuals in the population, corroborating the hypothesis that limited mating opportunities have favoured evolution of these diverse sexual systems, which have puzzled biologists since Darwin....

  3. Adaptive fractionation therapy: I. Basic concept and strategy

    International Nuclear Information System (INIS)

    Lu Weiguo; Chen Mingli; Chen Quan; Ruchala, Kenneth; Olivera, Gustavo

    2008-01-01

    Radiotherapy is fractionized to increase the therapeutic ratio. Fractionation in conventional treatment is determined as part of the prescription, and a fixed fraction size is used for the whole course of treatment. Due to patients' day-to-day variations on the relative distance between the tumor and the organs at risk (OAR), a better therapeutic ratio may be attained by using an adaptive fraction size. Intuitively, we want to use a larger fraction size when OAR and the tumor are far apart and a smaller fraction size when OAR and the tumor are close to each other. The concept and strategies of adaptive fractionation therapy (AFT) are introduced in this paper. AFT is an on-line adaptive technique that utilizes the variations of internal structures to get optimal OAR sparing. Changes of internal structures are classified as different configurations according to their feasibility to the radiation delivery. A priori knowledge is used to describe the probability distribution of these configurations. On-line processes include identifying the configuration via daily image guidance and optimizing the current fraction size. The optimization is modeled as a dynamic linear programming problem so that at the end of the treatment course, the tumor receives the same planned dose while OAR receives less dose than the regular fractionation delivery. Extensive simulations, which include thousands of treatment courses with each course consisting of 40 fractions, are used to test the efficiency and robustness of the presented technique. The gains of OAR sparing depend on the variations on configurations and the bounds of the fraction size. The larger the variations and the looser the bounds are, the larger the gains will be. Compared to the conventional fractionation technique with 2 Gy/fraction in 40 fractions, for a 20% variation on tumor-OAR configurations and [1 Gy, 3 Gy] fraction size bounds, the cumulative OAR dose with adaptive fractionation is 3-8 Gy, or 7-20% less than that

  4. Stochastic resonance and the evolution of Daphnia foraging strategy

    International Nuclear Information System (INIS)

    Dees, Nathan D; Bahar, Sonya; Moss, Frank

    2008-01-01

    Search strategies are currently of great interest, with reports on foraging ranging from albatrosses and spider monkeys to microzooplankton. Here, we investigate the role of noise in optimizing search strategies. We focus on the zooplankton Daphnia, which move in successive sequences consisting of a hop, a pause and a turn through an angle. Recent experiments have shown that their turning angle distributions (TADs) and underlying noise intensities are similar across species and age groups, suggesting an evolutionary origin of this internal noise. We explore this hypothesis further with a digital simulation (EVO) based solely on the three central Darwinian themes: inheritability, variability and survivability. Separate simulations utilizing stochastic resonance (SR) indicate that foraging success, and hence fitness, is maximized at an optimum TAD noise intensity, which is represented by the distribution's characteristic width, σ. In both the EVO and SR simulations, foraging success is the criterion, and the results are the predicted characteristic widths of the TADs that maximize success. Our results are twofold: (1) the evolving characteristic widths achieve stasis after many generations; (2) as a hop length parameter is changed, variations in the evolved widths generated by EVO parallel those predicted by SR. These findings provide support for the hypotheses that (1) σ is an evolved quantity and that (2) SR plays a role in evolution. (communication)

  5. Evolution of motion uncertainty in rectal cancer: implications for adaptive radiotherapy

    Science.gov (United States)

    Kleijnen, Jean-Paul J. E.; van Asselen, Bram; Burbach, Johannes P. M.; Intven, Martijn; Philippens, Marielle E. P.; Reerink, Onne; Lagendijk, Jan J. W.; Raaymakers, Bas W.

    2016-01-01

    Reduction of motion uncertainty by applying adaptive radiotherapy strategies depends largely on the temporal behavior of this motion. To fully optimize adaptive strategies, insight into target motion is needed. The purpose of this study was to analyze stability and evolution in time of motion uncertainty of both the gross tumor volume (GTV) and clinical target volume (CTV) for patients with rectal cancer. We scanned 16 patients daily during one week, on a 1.5 T MRI scanner in treatment position, prior to each radiotherapy fraction. Single slice sagittal cine MRIs were made at the beginning, middle, and end of each scan session, for one minute at 2 Hz temporal resolution. GTV and CTV motion were determined by registering a delineated reference frame to time-points later in time. The 95th percentile of observed motion (dist95%) was taken as a measure of motion. The stability of motion in time was evaluated within each cine-MRI separately. The evolution of motion was investigated between the reference frame and the cine-MRIs of a single scan session and between the reference frame and the cine-MRIs of several days later in the course of treatment. This observed motion was then converted into a PTV-margin estimate. Within a one minute cine-MRI scan, motion was found to be stable and small. Independent of the time-point within the scan session, the average dist95% remains below 3.6 mm and 2.3 mm for CTV and GTV, respectively 90% of the time. We found similar motion over time intervals from 18 min to 4 days. When reducing the time interval from 18 min to 1 min, a large reduction in motion uncertainty is observed. A reduction in motion uncertainty, and thus the PTV-margin estimate, of 71% and 75% for CTV and tumor was observed, respectively. Time intervals of 15 and 30 s yield no further reduction in motion uncertainty compared to a 1 min time interval.

  6. Adaptive Evolution and Demographic History of Norway Spruce (Picea Abies)

    OpenAIRE

    Källman, Thomas

    2009-01-01

    One of the major challenges in evolutionary biology is to determine the genetic basis of adaptive variation. In Norway spruce (Picea abies) the timing of bud set shows a very strong latitudinal cline despite a very low genetic differentiation between populations. The timing of bud set in Norway spruce is under strong genetic control and triggered by changes in photoperiod, but no genes controlling this response have so far been described. In this thesis we used a combination of functional stu...

  7. Make way for the climate. National adaptation strategy. The interdepartmental memorandum

    International Nuclear Information System (INIS)

    2007-11-01

    This memorandum describes the outline of a national strategy for adaptation to the consequences of climate change. The memorandum is the first report of the Adapting Spatial Planning to Climate Change programme (ARK). [mk] [nl

  8. Adaptive Laboratory Evolution of Antibiotic Resistance Using Different Selection Regimes Lead to Similar Phenotypes and Genotypes

    DEFF Research Database (Denmark)

    Jahn, Leonie Johanna; Munck, Christian; Ellabaan, Mostafa M Hashim

    2017-01-01

    independently of the selection regime. Yet, lineages that underwent evolution under mild selection displayed a growth advantage independently of the acquired level of antibiotic resistance compared to lineages adapted under maximal selection in a drug gradient. Our data suggests that even though different......Antibiotic resistance is a global threat to human health, wherefore it is crucial to study the mechanisms of antibiotic resistance as well as its emergence and dissemination. One way to analyze the acquisition of de novo mutations conferring antibiotic resistance is adaptive laboratory evolution....... However, various evolution methods exist that utilize different population sizes, selection strengths, and bottlenecks. While evolution in increasing drug gradients guarantees high-level antibiotic resistance promising to identify the most potent resistance conferring mutations, other selection regimes...

  9. Not different, Just Better: The Adaptive Evolution of an Enzyme

    Science.gov (United States)

    2015-12-20

    IS150 mutation has a pleiotropic effect across environments: it is neutral in most of the PTS environments (mean ± SEM: 0.981 ± 0.015), but has...pyruvate kinase found in Richard Lenski’s E. coli long- term evolution experiment. We have demonstrated, for the first time, that all the pykF mutations ...the mutations are likely to have a similar proximal basis of the benefit they confer: a shorter lag 1. REPORT DATE (DD-MM-YYYY) 4. TITLE AND SUBTITLE

  10. Brain evolution and development: adaptation, allometry and constraint

    Science.gov (United States)

    Barton, Robert A.

    2016-01-01

    Phenotypic traits are products of two processes: evolution and development. But how do these processes combine to produce integrated phenotypes? Comparative studies identify consistent patterns of covariation, or allometries, between brain and body size, and between brain components, indicating the presence of significant constraints limiting independent evolution of separate parts. These constraints are poorly understood, but in principle could be either developmental or functional. The developmental constraints hypothesis suggests that individual components (brain and body size, or individual brain components) tend to evolve together because natural selection operates on relatively simple developmental mechanisms that affect the growth of all parts in a concerted manner. The functional constraints hypothesis suggests that correlated change reflects the action of selection on distributed functional systems connecting the different sub-components, predicting more complex patterns of mosaic change at the level of the functional systems and more complex genetic and developmental mechanisms. These hypotheses are not mutually exclusive but make different predictions. We review recent genetic and neurodevelopmental evidence, concluding that functional rather than developmental constraints are the main cause of the observed patterns. PMID:27629025

  11. Adaptive Game Level Creation through Rank-based Interactive Evolution

    DEFF Research Database (Denmark)

    Liapis, Antonios; Martínez, Héctor Pérez; Togelius, Julian

    2013-01-01

    as fitness functions for the optimization of the generated content. The preference models are built via ranking-based preference learning, while the content is generated via evolutionary search. The proposed method is evaluated on the creation of strategy game maps, and its performance is tested using...

  12. Experiments on the role of deleterious mutations as stepping stones in adaptive evolution

    Science.gov (United States)

    Covert, Arthur W.; Lenski, Richard E.; Wilke, Claus O.; Ofria, Charles

    2013-01-01

    Many evolutionary studies assume that deleterious mutations necessarily impede adaptive evolution. However, a later mutation that is conditionally beneficial may interact with a deleterious predecessor before it is eliminated, thereby providing access to adaptations that might otherwise be inaccessible. It is unknown whether such sign-epistatic recoveries are inconsequential events or an important factor in evolution, owing to the difficulty of monitoring the effects and fates of all mutations during experiments with biological organisms. Here, we used digital organisms to compare the extent of adaptive evolution in populations when deleterious mutations were disallowed with control populations in which such mutations were allowed. Significantly higher fitness levels were achieved over the long term in the control populations because some of the deleterious mutations served as stepping stones across otherwise impassable fitness valleys. As a consequence, initially deleterious mutations facilitated the evolution of complex, beneficial functions. We also examined the effects of disallowing neutral mutations, of varying the mutation rate, and of sexual recombination. Populations evolving without neutral mutations were able to leverage deleterious and compensatory mutation pairs to overcome, at least partially, the absence of neutral mutations. Substantially raising or lowering the mutation rate reduced or eliminated the long-term benefit of deleterious mutations, but introducing recombination did not. Our work demonstrates that deleterious mutations can play an important role in adaptive evolution under at least some conditions. PMID:23918358

  13. Advances on molecular mechanism of the adaptive evolution of Chiroptera (bats).

    Science.gov (United States)

    Yunpeng, Liang; Li, Yu

    2015-01-01

    As the second biggest animal group in mammals, Chiroptera (bats) demonstrates many unique adaptive features in terms of flight, echolocation, auditory acuity, feeding habit, hibernation and immune defense, providing an excellent system for understanding the molecular basis of how organisms adapt to the living environments encountered. In this review, we summarize the researches on the molecular mechanism of the adaptive evolution of Chiroptera, especially the recent researches at the genome levels, suggesting a far more complex evolutionary pattern and functional diversity than previously thought. In the future, along with the increasing numbers of Chiroptera species genomes available, new evolutionary patterns and functional divergence will be revealed, which can promote the further understanding of this animal group and the molecular mechanism of adaptive evolution.

  14. Localizing recent adaptive evolution in the human genome

    DEFF Research Database (Denmark)

    Williamson, Scott H; Hubisz, Melissa J; Clark, Andrew G

    2007-01-01

    , clusters of olfactory receptors, genes involved in nervous system development and function, immune system genes, and heat shock genes. We also observe consistent evidence of selective sweeps in centromeric regions. In general, we find that recent adaptation is strikingly pervasive in the human genome......-nucleotide polymorphism ascertainment, while also providing fine-scale estimates of the position of the selected site, we analyzed a genomic dataset of 1.2 million human single-nucleotide polymorphisms genotyped in African-American, European-American, and Chinese samples. We identify 101 regions of the human genome...

  15. Convergent evolution and adaptation of Pseudomonas aeruginosa within patients with cystic fibrosis

    DEFF Research Database (Denmark)

    Marvig, Rasmus Lykke; Madsen Sommer, Lea Mette; Molin, Søren

    2015-01-01

    fibrosis. Our analysis of 36 P. aeruginosa lineages identified convergent molecular evolution in 52 genes. This list of genes suggests a role in host adaptation for remodeling of regulatory networks and central metabolism, acquisition of antibiotic resistance and loss of extracellular virulence factors....... Furthermore, we find an ordered succession of mutations in key regulatory networks. Accordingly, mutations in downstream transcriptional regulators were contingent upon mutations in upstream regulators, suggesting that remodeling of regulatory networks might be important in adaptation. The characterization...

  16. The genomic signatures of Shigella evolution, adaptation and geographical spread.

    Science.gov (United States)

    The, Hao Chung; Thanh, Duy Pham; Holt, Kathryn E; Thomson, Nicholas R; Baker, Stephen

    2016-04-01

    Shigella spp. are some of the key pathogens responsible for the global burden of diarrhoeal disease. These facultative intracellular bacteria belong to the family Enterobacteriaceae, together with other intestinal pathogens, such as Escherichia coli and Salmonella spp. The genus Shigella comprises four different species, each consisting of several serogroups, all of which show phenotypic similarity, including invasive pathogenicity. DNA sequencing suggests that this similarity results from the convergent evolution of different Shigella spp. founders. Here, we review the evolutionary relationships between Shigella spp. and E . coli, and we highlight how the genomic plasticity of these bacteria and their acquisition of a distinctive virulence plasmid have enabled the development of such highly specialized pathogens. Furthermore, we discuss the insights that genotyping and whole-genome sequencing have provided into the phylogenetics and intercontinental spread of Shigella spp.

  17. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    Directory of Open Access Journals (Sweden)

    Colas N. Authié

    2017-07-01

    Full Text Available In retinitis pigmentosa (RP, loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present, of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures.

  18. Adaptive Gaze Strategies for Locomotion with Constricted Visual Field

    Science.gov (United States)

    Authié, Colas N.; Berthoz, Alain; Sahel, José-Alain; Safran, Avinoam B.

    2017-01-01

    In retinitis pigmentosa (RP), loss of peripheral visual field accounts for most difficulties encountered in visuo-motor coordination during locomotion. The purpose of this study was to accurately assess the impact of peripheral visual field loss on gaze strategies during locomotion, and identify compensatory mechanisms. Nine RP subjects presenting a central visual field limited to 10–25° in diameter, and nine healthy subjects were asked to walk in one of three directions—straight ahead to a visual target, leftward and rightward through a door frame, with or without obstacle on the way. Whole body kinematics were recorded by motion capture, and gaze direction in space was reconstructed using an eye-tracker. Changes in gaze strategies were identified in RP subjects, including extensive exploration prior to walking, frequent fixations of the ground (even knowing no obstacle was present), of door edges, essentially of the proximal one, of obstacle edge/corner, and alternating door edges fixations when approaching the door. This was associated with more frequent, sometimes larger rapid-eye-movements, larger movements, and forward tilting of the head. Despite the visual handicap, the trajectory geometry was identical between groups, with a small decrease in walking speed in RPs. These findings identify the adaptive changes in sensory-motor coordination, in order to ensure visual awareness of the surrounding, detect changes in spatial configuration, collect information for self-motion, update the postural reference frame, and update egocentric distances to environmental objects. They are of crucial importance for the design of optimized rehabilitation procedures. PMID:28798674

  19. Battery parameterisation based on differential evolution via a boundary evolution strategy

    Science.gov (United States)

    Yang, Guangya

    2014-01-01

    Attention has been given to the battery modelling in the electric engineering field following the current development of renewable energy and electrification of transportation. The establishment of the equivalent circuit model of the battery requires data preparation and parameterisation. Besides, as the equivalent circuit model is an abstract map of the battery electric characteristics, the determination of the possible ranges of parameters can be a challenging task. In this paper, an efficient yet easy to implement method is proposed to parameterise the equivalent circuit model of batteries utilising the advances of evolutionary algorithms (EAs). Differential evolution (DE) is selected and modified to parameterise an equivalent circuit model of lithium-ion batteries. A boundary evolution strategy (BES) is developed and incorporated into the DE to update the parameter boundaries during the parameterisation. The method can parameterise the model without extensive data preparation. In addition, the approach can also estimate the initial SOC and the available capacity. The efficiency of the approach is verified through two battery packs, one is an 8-cell battery module and one from an electrical vehicle.

  20. Within-host evolution of Pseudomonas aeruginosa reveals adaptation toward iron acquisition from hemoglobin

    DEFF Research Database (Denmark)

    Marvig, Rasmus Lykke; Pedersen, Søren Damkiær; Khademi, Seyed Mohammad Hossein

    2014-01-01

    the within-host evolution of the transmissible P. aeruginosa DK2 lineage. We found positive selection for promoter mutations leading to increased expression of the phu system. By mimicking conditions of the CF airways in vitro, we experimentally demonstrate that increased expression of phuR confers a growth...... advantage in the presence of hemoglobin, thus suggesting that P. aeruginosa evolves toward iron acquisition from hemoglobin. To rule out that this adaptive trait is specific to the DK2 lineage, we inspected the genomes of additional P. aeruginosa lineages isolated from CF airways and found similar adaptive...... might therefore be a promising strategy for the treatment of P. aeruginosa infections in CF patients. IMPORTANCE Most bacterial pathogens depend on scavenging iron within their hosts, which makes the battle for iron between pathogens and hosts a hallmark of infection. Accordingly, the ability...

  1. Diversity and adaptive evolution of Saccharomyces wine yeast: a review

    Science.gov (United States)

    Marsit, Souhir; Dequin, Sylvie

    2015-01-01

    Saccharomyces cerevisiae and related species, the main workhorses of wine fermentation, have been exposed to stressful conditions for millennia, potentially resulting in adaptive differentiation. As a result, wine yeasts have recently attracted considerable interest for studying the evolutionary effects of domestication. The widespread use of whole-genome sequencing during the last decade has provided new insights into the biodiversity, population structure, phylogeography and evolutionary history of wine yeasts. Comparisons between S. cerevisiae isolates from various origins have indicated that a variety of mechanisms, including heterozygosity, nucleotide and structural variations, introgressions, horizontal gene transfer and hybridization, contribute to the genetic and phenotypic diversity of S. cerevisiae. This review will summarize the current knowledge on the diversity and evolutionary history of wine yeasts, focusing on the domestication fingerprints identified in these strains. PMID:26205244

  2. Climate adaptation in NVE's areas of responsibility - Strategy 2010 - 2014; Klimatilpasning innen NVEs ansvarsomraader - Strategi 2010 - 2014

    Energy Technology Data Exchange (ETDEWEB)

    Hamarsland, Arne T. (ed.)

    2010-09-15

    NVE has developed a comprehensive climate change strategies within their areas of responsibility. There is a systematic review of how a future climate change will affect NVE management areas; how to meet challenges, vulnerabilities, opportunities and proposals for adaptation measures. Climate adaptation is a dynamic process. It is therefore necessary to follow up the work continuously and correct direction at regular intervals. Climate change adaptation strategy of adaptation measures is a foundation and a direction sensor in NVE's business planning. (AG)

  3. An unsupervised adaptive strategy for constructing probabilistic roadmaps

    KAUST Repository

    Tapia, L.; Thomas, S.; Boyd, B.; Amato, N.M.

    2009-01-01

    difficult to answer, even when adaptive methods meant to facilitate a solution are applied. For example, adaptive solutions such as setting learning rates, hand-classifying spaces, and defining parameters for a library of planners have all been proposed. We

  4. Test Information Targeting Strategies for Adaptive Multistage Testing Designs.

    Science.gov (United States)

    Luecht, Richard M.; Burgin, William

    Adaptive multistage testlet (MST) designs appear to be gaining popularity for many large-scale computer-based testing programs. These adaptive MST designs use a modularized configuration of preconstructed testlets and embedded score-routing schemes to prepackage different forms of an adaptive test. The conditional information targeting (CIT)…

  5. Fire risk and adaptation strategies in Northern Eurasian forests

    Science.gov (United States)

    Shvidenko, Anatoly; Schepaschenko, Dmitry

    2013-04-01

    permafrost areas. Overall, Russia should expect a disproportionate escalation of fire regimes compared to increasing climatic fire danger. Thus, development and implementation of an efficient adaptation strategy is a pressing problem of current forest management of the country. An appropriate system of forest fire protection which would be able to meet challenges of future climates is a corner stone of such a strategy. We consider possible systems solutions of this complex problem including (1) integrated ecological and socio-economic analysis of current and future fire regimes; (2) regional requirements to and specific features of a new paradigm of forest fire protection in the boreal zone of Northern Eurasia; (3) anticipatory strategy of the prevention of large-scale disturbances in forests, including adaptation of forest landscapes to the future climates (regulation of tree composition; setup of relevant spatial structure of forest landscapes; etc.); (4) implementation of an effective system of forest monitoring as part of integrated observing systems; (5) transition to ecologically-friendly systems of industrial development of northern territories; (6) development of new/ improvement of existing legislation and institutional frameworks of forest management which would be satisfactory to react on challenges of climate change; and (6) international cooperation.

  6. Exaptation in human evolution: how to test adaptive vs exaptive evolutionary hypotheses.

    Science.gov (United States)

    Pievani, Telmo; Serrelli, Emanuele

    2011-01-01

    Palaeontologists, Stephen J. Gould and Elisabeth Vrba, introduced the term "ex-aptation" with the aim of improving and enlarging the scientific language available to researchers studying the evolution of any useful character, instead of calling it an "adaptation" by default, coming up with what Gould named an "extended taxonomy of fitness". With the extension to functional co-optations from non-adaptive structures ("spandrels"), the notion of exaptation expanded and revised the neo-Darwinian concept of "pre-adaptation" (which was misleading, for Gould and Vrba, suggesting foreordination). Exaptation is neither a "saltationist" nor an "anti-Darwinian" concept and, since 1982, has been adopted by many researchers in evolutionary and molecular biology, and particularly in human evolution. Exaptation has also been contested. Objections include the "non-operationality objection".We analyze the possible operationalization of this concept in two recent studies, and identify six directions of empirical research, which are necessary to test "adaptive vs. exaptive" evolutionary hypotheses. We then comment on a comprehensive survey of literature (available online), and on the basis of this we make a quantitative and qualitative evaluation of the adoption of the term among scientists who study human evolution. We discuss the epistemic conditions that may have influenced the adoption and appropriate use of exaptation, and comment on the benefits of an "extended taxonomy of fitness" in present and future studies concerning human evolution.

  7. The elusive nature of adaptive mitochondrial DNA evolution of an Arctic lineage prone to frequent introgression

    DEFF Research Database (Denmark)

    Melo-Ferreira, Jose; Vilela, Joana; Fonseca, Miguel M.

    2014-01-01

    understood. Hares (Lepus spp.) are privileged models to study the impact of natural selection on mitogenomic evolution because 1) species are adapted to contrasting environments, including arctic, with different metabolic pressures, and 2) mtDNA introgression from arctic into temperate species is widespread...

  8. Evolution of Alternative Adaptive Immune Systems in Vertebrates.

    Science.gov (United States)

    Boehm, Thomas; Hirano, Masayuki; Holland, Stephen J; Das, Sabyasachi; Schorpp, Michael; Cooper, Max D

    2018-04-26

    Adaptive immunity in jawless fishes is based on antigen recognition by three types of variable lymphocyte receptors (VLRs) composed of variable leucine-rich repeats, which are differentially expressed by two T-like lymphocyte lineages and one B-like lymphocyte lineage. The T-like cells express either VLRAs or VLRCs of yet undefined antigen specificity, whereas the VLRB antibodies secreted by B-like cells bind proteinaceous and carbohydrate antigens. The incomplete VLR germline genes are assembled into functional units by a gene conversion-like mechanism that employs flanking variable leucine-rich repeat sequences as templates in association with lineage-specific expression of cytidine deaminases. B-like cells develop in the hematopoietic typhlosole and kidneys, whereas T-like cells develop in the thymoid, a thymus-equivalent region at the gill fold tips. Thus, the dichotomy between T-like and B-like cells and the presence of dedicated lymphopoietic tissues emerge as ancestral vertebrate features, whereas the somatic diversification of structurally distinct antigen receptor genes evolved independently in jawless and jawed vertebrates.

  9. Molecular evolution of rbcL in three gymnosperm families: identifying adaptive and coevolutionary patterns

    LENUS (Irish Health Repository)

    Sen, Lin

    2011-06-03

    Abstract Background The chloroplast-localized ribulose-1, 5-biphosphate carboxylase\\/oxygenase (Rubisco), the primary enzyme responsible for autotrophy, is instrumental in the continual adaptation of plants to variations in the concentrations of CO2. The large subunit (LSU) of Rubisco is encoded by the chloroplast rbcL gene. Although adaptive processes have been previously identified at this gene, characterizing the relationships between the mutational dynamics at the protein level may yield clues on the biological meaning of such adaptive processes. The role of such coevolutionary dynamics in the continual fine-tuning of RbcL remains obscure. Results We used the timescale and phylogenetic analyses to investigate and search for processes of adaptive evolution in rbcL gene in three gymnosperm families, namely Podocarpaceae, Taxaceae and Cephalotaxaceae. To understand the relationships between regions identified as having evolved under adaptive evolution, we performed coevolutionary analyses using the software CAPS. Importantly, adaptive processes were identified at amino acid sites located on the contact regions among the Rubisco subunits and on the interface between Rubisco and its activase. Adaptive amino acid replacements at these regions may have optimized the holoenzyme activity. This hypothesis was pinpointed by evidence originated from our analysis of coevolution that supported the correlated evolution between Rubisco and its activase. Interestingly, the correlated adaptive processes between both these proteins have paralleled the geological variation history of the concentration of atmospheric CO2. Conclusions The gene rbcL has experienced bursts of adaptations in response to the changing concentration of CO2 in the atmosphere. These adaptations have emerged as a result of a continuous dynamic of mutations, many of which may have involved innovation of functional Rubisco features. Analysis of the protein structure and the functional implications of such

  10. TU-H-CAMPUS-JeP3-01: Towards Robust Adaptive Radiation Therapy Strategies

    International Nuclear Information System (INIS)

    Boeck, M; Eriksson, K; Hardemark, B; Forsgren, A

    2016-01-01

    Purpose: To set up a framework combining robust treatment planning with adaptive reoptimization in order to maintain high treatment quality, to respond to interfractional variations and to identify those patients who will benefit the most from an adaptive fractionation schedule. Methods: We propose adaptive strategies based on stochastic minimax optimization for a series of simulated treatments on a one-dimensional patient phantom. The plan should be able to handle anticipated systematic and random errors and is applied during the first fractions. Information on the individual geometric variations is gathered at each fraction. At scheduled fractions, the impact of the measured errors on the delivered dose distribution is evaluated. For a patient that receives a dose that does not satisfy specified plan quality criteria, the plan is reoptimized based on these individual measurements using one of three different adaptive strategies. The reoptimized plan is then applied during future fractions until a new scheduled adaptation becomes necessary. In the first adaptive strategy the measured systematic and random error scenarios and their assigned probabilities are updated to guide the robust reoptimization. The focus of the second strategy lies on variation of the fraction of the worst scenarios taken into account during robust reoptimization. In the third strategy the uncertainty margins around the target are recalculated with the measured errors. Results: By studying the effect of the three adaptive strategies combined with various adaptation schedules on the same patient population, the group which benefits from adaptation is identified together with the most suitable strategy and schedule. Preliminary computational results indicate when and how best to adapt for the three different strategies. Conclusion: A workflow is presented that provides robust adaptation of the treatment plan throughout the course of treatment and useful measures to identify patients in need

  11. Rampant adaptive evolution in regions of proteins with unknown function in Drosophila simulans.

    Directory of Open Access Journals (Sweden)

    Alisha K Holloway

    2007-10-01

    Full Text Available Adaptive protein evolution is pervasive in Drosophila. Genomic studies, thus far, have analyzed each protein as a single entity. However, the targets of adaptive events may be localized to particular parts of proteins, such as protein domains or regions involved in protein folding. We compared the population genetic mechanisms driving sequence polymorphism and divergence in defined protein domains and non-domain regions. Interestingly, we find that non-domain regions of proteins are more frequent targets of directional selection. Protein domains are also evolving under directional selection, but appear to be under stronger purifying selection than non-domain regions. Non-domain regions of proteins clearly play a major role in adaptive protein evolution on a genomic scale and merit future investigations of their functional properties.

  12. Adaptive evolution in locomotor performance: How selective pressures and functional relationships produce diversity.

    Science.gov (United States)

    Scales, Jeffrey A; Butler, Marguerite A

    2016-01-01

    Despite the complexity of nature, most comparative studies of phenotypic evolution consider selective pressures in isolation. When competing pressures operate on the same system, it is commonly expected that trade-offs will occur that will limit the evolution of phenotypic diversity, however, it is possible that interactions among selective pressures may promote diversity instead. We explored the evolution of locomotor performance in lizards in relation to possible selective pressures using the Ornstein-Uhlenbeck process. Here, we show that a combination of selection based on foraging mode and predator escape is required to explain variation in performance phenotypes. Surprisingly, habitat use contributed little explanatory power. We find that it is possible to evolve very different abilities in performance which were previously thought to be tightly correlated, supporting a growing literature that explores the many-to-one mapping of morphological design. Although we generally find the expected trade-off between maximal exertion and speed, this relationship surprisingly disappears when species experience selection for both performance types. We conclude that functional integration need not limit adaptive potential, and that an integrative approach considering multiple major influences on a phenotype allows a more complete understanding of adaptation and the evolution of diversity. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  13. Adaptive Strategies, Gender Ideology, and Work-Family Balance among Dutch Dual Earners

    Science.gov (United States)

    Wierda-Boer, Hilde H.; Gerris, Jan R. M.; Vermulst, Ad A.

    2008-01-01

    Using questionnaire data on 149 Dutch dual-earner couples with young children participating in the European Famwork study, we examine how adaptive strategies and gender ideology relate to parents' perceived success in balancing work and family. Path analysis indicates that some adaptive strategies may harm individuals' work-family balance,…

  14. Online adaptive approach for a game-theoretic strategy for complete vehicle energy management

    NARCIS (Netherlands)

    Chen, H.; Kessels, J.T.B.A.; Weiland, S.

    2015-01-01

    This paper introduces an adaptive approach for a game-theoretic strategy on Complete Vehicle Energy Management. The proposed method enhances the game-theoretic approach such that the strategy is able to adapt to real driving behavior. The classical game-theoretic approach relies on one probability

  15. Adaptation to Temporally Fluctuating Environments by the Evolution of Maternal Effects.

    Directory of Open Access Journals (Sweden)

    Snigdhadip Dey

    2016-02-01

    Full Text Available All organisms live in temporally fluctuating environments. Theory predicts that the evolution of deterministic maternal effects (i.e., anticipatory maternal effects or transgenerational phenotypic plasticity underlies adaptation to environments that fluctuate in a predictably alternating fashion over maternal-offspring generations. In contrast, randomizing maternal effects (i.e., diversifying and conservative bet-hedging, are expected to evolve in response to unpredictably fluctuating environments. Although maternal effects are common, evidence for their adaptive significance is equivocal since they can easily evolve as a correlated response to maternal selection and may or may not increase the future fitness of offspring. Using the hermaphroditic nematode Caenorhabditis elegans, we here show that the experimental evolution of maternal glycogen provisioning underlies adaptation to a fluctuating normoxia-anoxia hatching environment by increasing embryo survival under anoxia. In strictly alternating environments, we found that hermaphrodites evolved the ability to increase embryo glycogen provisioning when they experienced normoxia and to decrease embryo glycogen provisioning when they experienced anoxia. At odds with existing theory, however, populations facing irregularly fluctuating normoxia-anoxia hatching environments failed to evolve randomizing maternal effects. Instead, adaptation in these populations may have occurred through the evolution of fitness effects that percolate over multiple generations, as they maintained considerably high expected growth rates during experimental evolution despite evolving reduced fecundity and reduced embryo survival under one or two generations of anoxia. We develop theoretical models that explain why adaptation to a wide range of patterns of environmental fluctuations hinges on the existence of deterministic maternal effects, and that such deterministic maternal effects are more likely to contribute to

  16. Climate change perceptions and local adaptation strategies of hazard-prone rural households in Bangladesh

    OpenAIRE

    G.M. Monirul Alam; Khorshed Alam; Shahbaz Mushtaq

    2017-01-01

    Adaptation is a key strategy that can alleviate the severity of climate change impacts on agriculture and food production. Adaptation strategies are unlikely to be effective without an understanding of the farmers’ perceptions of climate change. This paper explores the local knowledge of adaptation in response to the perceived impacts of climate change and climatic hazards using a survey of 380 resource-poor riverbank erosion-prone households in Bangladesh. The results indicate that the respo...

  17. Adapt and cope : strategies for safeguarding the quality of life in a shrinking ageing region

    OpenAIRE

    Steinführer, Annett; Küpper, Patrick; Tautz, Alexandra

    2014-01-01

    "This article examines the adaptation and coping strategies that are in place to safeguard the quality of life in a shrinking ageing region. In particular, it is investigated which resources are available to local policy-makers and the older population in order to pursue this goal. Following an introduction to the debate of regional science about demographic change and its consequences, we introduce a theoretical differentiation between adaptation and coping. Adaptation strategies refer to th...

  18. Exploiting adaptive laboratory evolution of Streptomyces clavuligerus for antibiotic discovery and overproduction.

    Directory of Open Access Journals (Sweden)

    Pep Charusanti

    Full Text Available Adaptation is normally viewed as the enemy of the antibiotic discovery and development process because adaptation among pathogens to antibiotic exposure leads to resistance. We present a method here that, in contrast, exploits the power of adaptation among antibiotic producers to accelerate the discovery of antibiotics. A competition-based adaptive laboratory evolution scheme is presented whereby an antibiotic-producing microorganism is competed against a target pathogen and serially passed over time until the producer evolves the ability to synthesize a chemical entity that inhibits growth of the pathogen. When multiple Streptomyces clavuligerus replicates were adaptively evolved against methicillin-resistant Staphylococcus aureus N315 in this manner, a strain emerged that acquired the ability to constitutively produce holomycin. In contrast, no holomycin could be detected from the unevolved wild-type strain. Moreover, genome re-sequencing revealed that the evolved strain had lost pSCL4, a large 1.8 Mbp plasmid, and acquired several single nucleotide polymorphisms in genes that have been shown to affect secondary metabolite biosynthesis. These results demonstrate that competition-based adaptive laboratory evolution can constitute a platform to create mutants that overproduce known antibiotics and possibly to discover new compounds as well.

  19. An adaptive grid refinement strategy for the simulation of negative streamers

    International Nuclear Information System (INIS)

    Montijn, C.; Hundsdorfer, W.; Ebert, U.

    2006-01-01

    The evolution of negative streamers during electric breakdown of a non-attaching gas can be described by a two-fluid model for electrons and positive ions. It consists of continuity equations for the charged particles including drift, diffusion and reaction in the local electric field, coupled to the Poisson equation for the electric potential. The model generates field enhancement and steep propagating ionization fronts at the tip of growing ionized filaments. An adaptive grid refinement method for the simulation of these structures is presented. It uses finite volume spatial discretizations and explicit time stepping, which allows the decoupling of the grids for the continuity equations from those for the Poisson equation. Standard refinement methods in which the refinement criterion is based on local error monitors fail due to the pulled character of the streamer front that propagates into a linearly unstable state. We present a refinement method which deals with all these features. Tests on one-dimensional streamer fronts as well as on three-dimensional streamers with cylindrical symmetry (hence effectively 2D for numerical purposes) are carried out successfully. Results on fine grids are presented, they show that such an adaptive grid method is needed to capture the streamer characteristics well. This refinement strategy enables us to adequately compute negative streamers in pure gases in the parameter regime where a physical instability appears: branching streamers

  20. Adaptive microclimatic structural and expressional dehydrin 1 evolution in wild barley, Hordeum spontaneum, at 'Evolution Canyon', Mount Carmel, Israel.

    Science.gov (United States)

    Yang, Zujun; Zhang, Tao; Bolshoy, Alexander; Beharav, Alexander; Nevo, Eviatar

    2009-05-01

    'Evolution Canyon' (ECI) at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unravelling evolution in action highlighting the twin evolutionary processes of adaptation and speciation. A major model organism in ECI is wild barley, Hordeum spontaneum, the progenitor of cultivated barley, which displays dramatic interslope adaptive and speciational divergence on the 'African' dry slope (AS) and the 'European' humid slope (ES), separated on average by 200 m. Here we examined interslope single nucleotide polymorphism (SNP) sequences and the expression diversity of the drought resistant dehydrin 1 gene (Dhn1) between the opposite slopes. We analysed 47 plants (genotypes), 4-10 individuals in each of seven stations (populations) in an area of 7000 m(2), for Dhn1 sequence diversity located in the 5' upstream flanking region of the gene. We found significant levels of Dhn1 genic diversity represented by 29 haplotypes, derived from 45 SNPs in a total of 708 bp sites. Most of the haplotypes, 25 out of 29 (= 86.2%), were represented by one genotype; hence, unique to one population. Only a single haplotype was common to both slopes. Genetic divergence of sequence and haplotype diversity was generally and significantly different among the populations and slopes. Nucleotide diversity was higher on the AS, whereas haplotype diversity was higher on the ES. Interslope divergence was significantly higher than intraslope divergence. The applied Tajima D rejected neutrality of the SNP diversity. The Dhn1 expression under dehydration indicated interslope divergent expression between AS and ES genotypes, reinforcing Dhn1 associated with drought resistance of wild barley at 'Evolution Canyon'. These results are inexplicable by mutation, gene flow, or chance effects, and support adaptive natural microclimatic selection as the major evolutionary divergent driving force.

  1. Can the experimental evolution programme help us elucidate the genetic basis of adaptation in nature?

    DEFF Research Database (Denmark)

    Bailey, Susan; Bataillon, Thomas

    2015-01-01

    and continue to play an important role in shaping adaptive evolution in the natural world. Further to this, experimental evolution studies allow for tests of theories that may be difficult or impossible to test in natural populations for logistical and methodological reasons and can even generate new insights......, suggesting further refinement of existing theories. However, as experimental evolution studies often take place in a very particular set of controlled conditions – that is simple environments, a small range of usually asexual species, relatively short timescales – the question remains as to how applicable...... natural population studies. We finish by making suggestions for future work in particular a need for natural population genomic time series data, as well as the necessity for studies that combine both experimental evolution and natural population approaches....

  2. Variable mutation rates as an adaptive strategy in replicator populations.

    Directory of Open Access Journals (Sweden)

    Michael Stich

    2010-06-01

    Full Text Available For evolving populations of replicators, there is much evidence that the effect of mutations on fitness depends on the degree of adaptation to the selective pressures at play. In optimized populations, most mutations have deleterious effects, such that low mutation rates are favoured. In contrast to this, in populations thriving in changing environments a larger fraction of mutations have beneficial effects, providing the diversity necessary to adapt to new conditions. What is more, non-adapted populations occasionally benefit from an increase in the mutation rate. Therefore, there is no optimal universal value of the mutation rate and species attempt to adjust it to their momentary adaptive needs. In this work we have used stationary populations of RNA molecules evolving in silico to investigate the relationship between the degree of adaptation of an optimized population and the value of the mutation rate promoting maximal adaptation in a short time to a new selective pressure. Our results show that this value can significantly differ from the optimal value at mutation-selection equilibrium, being strongly influenced by the structure of the population when the adaptive process begins. In the short-term, highly optimized populations containing little variability respond better to environmental changes upon an increase of the mutation rate, whereas populations with a lower degree of optimization but higher variability benefit from reducing the mutation rate to adapt rapidly. These findings show a good agreement with the behaviour exhibited by actual organisms that replicate their genomes under broadly different mutation rates.

  3. Contemporary evolution during invasion: evidence for differentiation, natural selection, and local adaptation.

    Science.gov (United States)

    Colautti, Robert I; Lau, Jennifer A

    2015-05-01

    Biological invasions are 'natural' experiments that can improve our understanding of contemporary evolution. We evaluate evidence for population differentiation, natural selection and adaptive evolution of invading plants and animals at two nested spatial scales: (i) among introduced populations (ii) between native and introduced genotypes. Evolution during invasion is frequently inferred, but rarely confirmed as adaptive. In common garden studies, quantitative trait differentiation is only marginally lower (~3.5%) among introduced relative to native populations, despite genetic bottlenecks and shorter timescales (i.e. millennia vs. decades). However, differentiation between genotypes from the native vs. introduced range is less clear and confounded by nonrandom geographic sampling; simulations suggest this causes a high false-positive discovery rate (>50%) in geographically structured populations. Selection differentials (¦s¦) are stronger in introduced than in native species, although selection gradients (¦β¦) are not, consistent with introduced species experiencing weaker genetic constraints. This could facilitate rapid adaptation, but evidence is limited. For example, rapid phenotypic evolution often manifests as geographical clines, but simulations demonstrate that nonadaptive trait clines can evolve frequently during colonization (~two-thirds of simulations). Additionally, QST-FST studies may often misrepresent the strength and form of natural selection acting during invasion. Instead, classic approaches in evolutionary ecology (e.g. selection analysis, reciprocal transplant, artificial selection) are necessary to determine the frequency of adaptive evolution during invasion and its influence on establishment, spread and impact of invasive species. These studies are rare but crucial for managing biological invasions in the context of global change. © 2015 John Wiley & Sons Ltd.

  4. Queens and Workers Contribute Differently to Adaptive Evolution in Bumble Bees and Honey Bees.

    Science.gov (United States)

    Harpur, Brock A; Dey, Alivia; Albert, Jennifer R; Patel, Sani; Hines, Heather M; Hasselmann, Martin; Packer, Laurence; Zayed, Amro

    2017-09-01

    Eusociality represents a major transition in evolution and is typified by cooperative brood care and reproductive division of labor between generations. In bees, this division of labor allows queens and workers to phenotypically specialize. Worker traits associated with helping are thought to be crucial to the fitness of a eusocial lineage, and recent studies of honey bees (genus Apis) have found that adaptively evolving genes often have worker-biased expression patterns. It is unclear however if worker-biased genes are disproportionately acted on by strong positive selection in all eusocial insects. We undertook a comparative population genomics study of bumble bees (Bombus) and honey bees to quantify natural selection on queen- and worker-biased genes across two levels of social complexity. Despite sharing a common eusocial ancestor, genes, and gene groups with the highest levels of positive selection were often unique within each genus, indicating that life history and the environment, but not sociality per se, drives patterns of adaptive molecular evolution. We uncovered differences in the contribution of queen- and worker-biased genes to adaptive evolution in bumble bees versus honey bees. Unlike honey bees, where worker-biased genes are enriched for signs of adaptive evolution, genes experiencing positive selection in bumble bees were predominately expressed by reproductive foundresses during the initial solitary-founding stage of colonies. Our study suggests that solitary founding is a major selective pressure and that the loss of queen totipotency may cause a change in the architecture of selective pressures upon the social insect genome. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution.

  5. A Convergent Differential Evolution Algorithm with Hidden Adaptation Selection for Engineering Optimization

    Directory of Open Access Journals (Sweden)

    Zhongbo Hu

    2014-01-01

    Full Text Available Many improved differential Evolution (DE algorithms have emerged as a very competitive class of evolutionary computation more than a decade ago. However, few improved DE algorithms guarantee global convergence in theory. This paper developed a convergent DE algorithm in theory, which employs a self-adaptation scheme for the parameters and two operators, that is, uniform mutation and hidden adaptation selection (haS operators. The parameter self-adaptation and uniform mutation operator enhance the diversity of populations and guarantee ergodicity. The haS can automatically remove some inferior individuals in the process of the enhancing population diversity. The haS controls the proposed algorithm to break the loop of current generation with a small probability. The breaking probability is a hidden adaptation and proportional to the changes of the number of inferior individuals. The proposed algorithm is tested on ten engineering optimization problems taken from IEEE CEC2011.

  6. Affect-Aware Adaptive Tutoring Based on Human-Automation Etiquette Strategies.

    Science.gov (United States)

    Yang, Euijung; Dorneich, Michael C

    2018-06-01

    We investigated adapting the interaction style of intelligent tutoring system (ITS) feedback based on human-automation etiquette strategies. Most ITSs adapt the content difficulty level, adapt the feedback timing, or provide extra content when they detect cognitive or affective decrements. Our previous work demonstrated that changing the interaction style via different feedback etiquette strategies has differential effects on students' motivation, confidence, satisfaction, and performance. The best etiquette strategy was also determined by user frustration. Based on these findings, a rule set was developed that systemically selected the proper etiquette strategy to address one of four learning factors (motivation, confidence, satisfaction, and performance) under two different levels of user frustration. We explored whether etiquette strategy selection based on this rule set (systematic) or random changes in etiquette strategy for a given level of frustration affected the four learning factors. Participants solved mathematics problems under different frustration conditions with feedback that adapted dynamic changes in etiquette strategies either systematically or randomly. The results demonstrated that feedback with etiquette strategies chosen systematically via the rule set could selectively target and improve motivation, confidence, satisfaction, and performance more than changing etiquette strategies randomly. The systematic adaptation was effective no matter the level of frustration for the participant. If computer tutors can vary the interaction style to effectively mitigate negative emotions, then ITS designers would have one more mechanism in which to design affect-aware adaptations that provide the proper responses in situations where human emotions affect the ability to learn.

  7. The evolution of resource adaptation: how generalist and specialist consumers evolve.

    Science.gov (United States)

    Ma, Junling; Levin, Simon A

    2006-07-01

    Why and how specialist and generalist strategies evolve are important questions in evolutionary ecology. In this paper, with the method of adaptive dynamics and evolutionary branching, we identify conditions that select for specialist and generalist strategies. Generally, generalist strategies evolve if there is a switching benefit; specialists evolve if there is a switching cost. If the switching cost is large, specialists always evolve. If the switching cost is small, even though the consumer will first evolve toward a generalist strategy, it will eventually branch into two specialists.

  8. Employee stress management: An examination of adaptive and maladaptive coping strategies on employee health.

    Science.gov (United States)

    Holton, M Kim; Barry, Adam E; Chaney, J Don

    2015-01-01

    Employees commonly report feeling stressed at work. Examine how employees cope with work and personal stress, whether their coping strategies are adaptive (protective to health) or maladaptive (detrimental to health), and if the manner in which employees cope with stress influences perceived stress management. In this cross-sectional study, a random sample of 2,500 full-time university non-student employees (i.e. faculty, salaried professionals, and hourly non-professionals) were surveyed on health related behaviors including stress and coping. Approximately 1,277 completed the survey (51% ). Hierarchical logistic regression was used to assess the ability of adaptive and maladaptive coping strategies to predict self-reported stress management, while controlling for multiple demographic variables. Over half of employees surveyed reported effective stress management. Most frequently used adaptive coping strategies were communication with friend/family member and exercise, while most frequently used maladaptive coping strategies were drinking alcohol and eating more than usual. Both adaptive and maladaptive coping strategies made significant (p stress management. Only adaptive coping strategies (B = 0.265) predicted whether someone would self-identify as effectively managing stress. Use of maladaptive coping strategies decreased likelihood of self-reporting effective stress management. Actual coping strategies employed may influence employees' perceived stress management. Adaptive coping strategies may be more influential than maladaptive coping strategies on perceived stress management. Results illustrate themes for effective workplace stress management programs. Stress management programs focused on increasing use of adaptive coping may have a greater impact on employee stress management than those focused on decreasing use of maladaptive coping. Coping is not only a reaction to stressful experiences but also a consequence of coping resources. Thereby increasing the

  9. Genomics of adaptation during experimental evolution of the opportunistic pathogen Pseudomonas aeruginosa.

    Directory of Open Access Journals (Sweden)

    Alex Wong

    2012-09-01

    Full Text Available Adaptation is likely to be an important determinant of the success of many pathogens, for example when colonizing a new host species, when challenged by antibiotic treatment, or in governing the establishment and progress of long-term chronic infection. Yet, the genomic basis of adaptation is poorly understood in general, and for pathogens in particular. We investigated the genetics of adaptation to cystic fibrosis-like culture conditions in the presence and absence of fluoroquinolone antibiotics using the opportunistic pathogen Pseudomonas aeruginosa. Whole-genome sequencing of experimentally evolved isolates revealed parallel evolution at a handful of known antibiotic resistance genes. While the level of antibiotic resistance was largely determined by these known resistance genes, the costs of resistance were instead attributable to a number of mutations that were specific to individual experimental isolates. Notably, stereotypical quinolone resistance mutations in DNA gyrase often co-occurred with other mutations that, together, conferred high levels of resistance but no consistent cost of resistance. This result may explain why these mutations are so prevalent in clinical quinolone-resistant isolates. In addition, genes involved in cyclic-di-GMP signalling were repeatedly mutated in populations evolved in viscous culture media, suggesting a shared mechanism of adaptation to this CF-like growth environment. Experimental evolutionary approaches to understanding pathogen adaptation should provide an important complement to studies of the evolution of clinical isolates.

  10. Evolution of plasticity and adaptive responses to climate change along climate gradients.

    Science.gov (United States)

    Kingsolver, Joel G; Buckley, Lauren B

    2017-08-16

    The relative contributions of phenotypic plasticity and adaptive evolution to the responses of species to recent and future climate change are poorly understood. We combine recent (1960-2010) climate and phenotypic data with microclimate, heat balance, demographic and evolutionary models to address this issue for a montane butterfly, Colias eriphyle , along an elevational gradient. Our focal phenotype, wing solar absorptivity, responds plastically to developmental (pupal) temperatures and plays a central role in thermoregulatory adaptation in adults. Here, we show that both the phenotypic and adaptive consequences of plasticity vary with elevation. Seasonal changes in weather generate seasonal variation in phenotypic selection on mean and plasticity of absorptivity, especially at lower elevations. In response to climate change in the past 60 years, our models predict evolutionary declines in mean absorptivity (but little change in plasticity) at high elevations, and evolutionary increases in plasticity (but little change in mean) at low elevation. The importance of plasticity depends on the magnitude of seasonal variation in climate relative to interannual variation. Our results suggest that selection and evolution of both trait means and plasticity can contribute to adaptive response to climate change in this system. They also illustrate how plasticity can facilitate rather than retard adaptive evolutionary responses to directional climate change in seasonal environments. © 2017 The Author(s).

  11. climate change adaptation strategies by local farmers in kilombero

    African Journals Online (AJOL)

    Osondu

    climatic stresses? What are institutions and political structures influencing local farmer's adaptive capacity? ... ability of the systems to adjust to climate change and has three ..... seedlings, and use of improved seed varieties. Political structures ...

  12. Hologenomic adaptations underlying the evolution of sanguivory in the common vampire bat

    DEFF Research Database (Denmark)

    Zepeda Mendoza, M. Lisandra; Xiong, Zijun; Escalera-Zamudio, Marina

    2018-01-01

    Adaptation to specialized diets often requires modifications at both genomic and microbiome levels. We applied a hologenomic approach to the common vampire bat (Desmodus rotundus), one of the only three obligate blood-feeding (sanguivorous) mammals, to study the evolution of its complex dietary...... adaptation. Specifically, we assembled its high-quality reference genome (scaffold N50 = 26.9 Mb, contig N50 = 36.6 kb) and gut metagenome, and compared them against those of insectivorous, frugivorous and carnivorous bats. Our analyses showed a particular common vampire bat genomic landscape regarding...

  13. Adaptive Reuse as A Strategy Toward Urban Resilience

    OpenAIRE

    Deniz Ozge Aytac; Tulin Vural Arslan; Selen Durak

    2016-01-01

    The significance of urban development has been realized again while acute shocks and chronic stresses (earthquake or unemployment) affect cities in a negative way. Therefore, urban resilience becomes more important for economic, environmental, and social sustainability of the built environment. There is a wide range of approaches to resilience in the literature such as ecological, engineering, and adaptive systems. Unlike others, adaptive resilience establishes a co-evolutionary interaction b...

  14. Sleep Strategies of Night-Shift Nurses on Days Off: Which Ones are Most Adaptive?

    Science.gov (United States)

    Petrov, Megan E; Clark, C Brendan; Molzof, Hylton E; Johnson, Russell L; Cropsey, Karen L; Gamble, Karen L

    2014-01-01

    To determine the off-shift sleep strategies of bi-ethnic night-shift nurses, the relationship between these sleep strategies and adaptation to shift work, and identify the participant-level characteristics associated with a given sleep strategy. African-American and non-Hispanic White female, night-shift nurses from an academic hospital were recruited to complete a survey on sleep-wake patterns (n = 213). Participants completed the standard shiftwork index and the biological clocks questionnaire to determine sleep strategies and adaptation to night-shift work. In addition, chronotype was determined quantitatively with a modified version of the Munich ChronoType Questionnaire. Most participants worked ~3 consecutive 12-h night-shifts followed by several days off. Five sleep strategies used on days off were identified: (a) night stay, (b) nap proxy, (c) switch sleeper, (d) no sleep, and (e) incomplete switcher. Nap proxy and no sleep types were associated with poorer adaptation to night-shift work. The switch sleeper and incomplete switcher types were identified as more adaptive strategies that were associated with less sleep disturbance, a later chronotype, and less cardiovascular problems. Behavioral sleep strategies are related to adaptation to a typical night-shift schedule among hospital nurses. Nurses are crucial to the safety and well-being of their patients. Therefore, adoption of more adaptive sleep strategies may reduce sleep/wake dysregulation in this population, and improve cardiovascular outcomes.

  15. Coastal zones : shifting shores, sharing adaptation strategies for coastal environments

    Energy Technology Data Exchange (ETDEWEB)

    Hay, J.E. [Waikato Univ. (New Zealand); Morneau, F.; Savard, J.P. [Ouranos, Montreal, PQ (Canada); Madruga, R.P. [Centre of Investigation on the Global Economy (Cuba); Leslie, K.R. [Caribbean Community Climate Change Centre (Belize); Agricole, W. [Ministry of Environment and Natural Resources (Seychelles); Burkett, V. [United States Geological Survey (United States)

    2006-07-01

    A parallel event to the eleventh Conference of Parties (COP) to the United Nations Framework Convention of Climate Change was held to demonstrate examples of adaptation from around the world in the areas of food security, water resources, coastal zones, and communities/infrastructure. Panels on each theme presented examples from developing countries, countries in economic transition, and developed countries. These 4 themes were chosen because both mitigation and adaptation are essential to meeting the challenge of climate change. The objective of the event was to improve the knowledge of Canada's vulnerabilities to climate change, identify ways to minimize the negative effects of future impacts, and explore opportunities that take advantage of any positive impacts. This third session focused on how coastal communities are adapting to climate change in such places as Quebec, the Caribbean, and small Island States. It also presented the example of how a developed country became vulnerable to Hurricane Katrina which hit the coastal zone in the United States Gulf of Mexico. The presentations addressed the challenges facing coastal communities along with progress in risk assessment and adaptation both globally and in the Pacific. Examples of coastal erosion in Quebec resulting from climate change were presented along with climate change and variability impacts over the coastal zones of Seychelles. Cuba's vulnerability and adaptation to climate change was discussed together with an integrated operational approach to climate change, adaptation, biodiversity and land utilization in the Caribbean region. The lessons learned from around the world emphasize that adaptation is needed to reduce unavoidable risks posed by climate change and to better prepare for the changes ahead. refs., tabs., figs.

  16. Evolution of the Marginal Ice Zone: Adaptive Sampling with Autonomous Gliders

    Science.gov (United States)

    2015-09-30

    release; distribution is unlimited. Evolution of the Marginal Ice Zone: Adaptive Sampling with Autonomous Gliders Craig M. Lee, Luc Rainville and Jason I...missions in ice-covered waters , where they provide several unique capabilities. Ice-capable Seagliders can maintain persistent (many months) sampling ...irradiance. Careful calibration casts, including water sampling , were conducted during both the deployment and recovery cruises. An example of a

  17. Dancing to a Different Tune: Adaptive Evolution Fine-Tunes Protein Dynamics

    Science.gov (United States)

    2015-09-01

    efficiency at low temperatures when the enzymes from mesophilic bacteria were evolved to have stabilities as high as their thermophilic homologs. The work...wild-type enzyme . This unfolding temperature is relatively high for a non- thermophilic enzyme ,15 as mesophilic enzymes typically unfold below 60 °C...The work described in this thesis provides a case study exploring the molecular changes underlying adaptive evolution in a key allosteric enzyme . It

  18. Evolution of quantum and classical strategies on networks by group interactions

    International Nuclear Information System (INIS)

    Li Qiang; Chen Minyou; Iqbal, Azhar; Abbott, Derek

    2012-01-01

    In this paper, quantum strategies are introduced within evolutionary games in order to investigate the evolution of quantum and classical strategies on networks in the public goods game. Comparing the results of evolution on a scale-free network and a square lattice, we find that a quantum strategy outperforms the classical strategies, regardless of the network. Moreover, a quantum strategy dominates the population earlier in group interactions than it does in pairwise interactions. In particular, if the hub node in a scale-free network is occupied by a cooperator initially, the strategy of cooperation will prevail in the population. However, in other situations, a quantum strategy can defeat the classical ones and finally becomes the dominant strategy in the population. (paper)

  19. Parameter extraction of different fuel cell models with transferred adaptive differential evolution

    International Nuclear Information System (INIS)

    Gong, Wenyin; Yan, Xuesong; Liu, Xiaobo; Cai, Zhihua

    2015-01-01

    To improve the design and control of FC (fuel cell) models, it is important to extract their unknown parameters. Generally, the parameter extraction problems of FC models can be transformed as nonlinear and multi-variable optimization problems. To extract the parameters of different FC models exactly and fast, in this paper, we propose a transferred adaptive DE (differential evolution) framework, in which the successful parameters of the adaptive DE solving previous problems are properly transferred to solve new optimization problems in the similar problem-domains. Based on this framework, an improved adaptive DE method (TRADE, in short) is presented as an illustration. To verify the performance of our proposal, TRADE is used to extract the unknown parameters of two types of fuel cell models, i.e., PEMFC (proton exchange membrane fuel cell) and SOFC (solid oxide fuel cell). The results of TRADE are also compared with those of other state-of-the-art EAs (evolutionary algorithms). Even though the modification is very simple, the results indicate that TRADE can extract the parameters of both PEMFC and SOFC models exactly and fast. Moreover, the V–I characteristics obtained by TRADE agree well with the simulated and experimental data in all cases for both types of fuel cell models. Also, it improves the performance of the original adaptive DE significantly in terms of both the quality of final solutions and the convergence speed in all cases. Additionally, TRADE is able to provide better results compared with other EAs. - Highlights: • A framework of transferred adaptive differential evolution is proposed. • Based on the framework, an improved differential evolution (TRADE) is presented. • TRADE obtains very promising results to extract the parameters of PEMFC and SOFC models

  20. Evolution of regulatory networks towards adaptability and stability in a changing environment

    Science.gov (United States)

    Lee, Deok-Sun

    2014-11-01

    Diverse biological networks exhibit universal features distinguished from those of random networks, calling much attention to their origins and implications. Here we propose a minimal evolution model of Boolean regulatory networks, which evolve by selectively rewiring links towards enhancing adaptability to a changing environment and stability against dynamical perturbations. We find that sparse and heterogeneous connectivity patterns emerge, which show qualitative agreement with real transcriptional regulatory networks and metabolic networks. The characteristic scaling behavior of stability reflects the balance between robustness and flexibility. The scaling of fluctuation in the perturbation spread shows a dynamic crossover, which is analyzed by investigating separately the stochasticity of internal dynamics and the network structure differences depending on the evolution pathways. Our study delineates how the ambivalent pressure of evolution shapes biological networks, which can be helpful for studying general complex systems interacting with environments.

  1. Evaluation of delivered dose for a clinical daily adaptive plan selection strategy for bladder cancer radiotherapy

    International Nuclear Information System (INIS)

    Lutkenhaus, Lotte J.; Visser, Jorrit; Jong, Rianne de; Hulshof, Maarten C.C.M.; Bel, Arjan

    2015-01-01

    Purpose: To account for variable bladder size during bladder cancer radiotherapy, a daily plan selection strategy was implemented. The aim of this study was to calculate the actually delivered dose using an adaptive strategy, compared to a non-adaptive approach. Material and methods: Ten patients were treated to the bladder and lymph nodes with an adaptive full bladder strategy. Interpolated delineations of bladder and tumor on a full and empty bladder CT scan resulted in five PTVs for which VMAT plans were created. Daily cone beam CT (CBCT) scans were used for plan selection. Bowel, rectum and target volumes were delineated on these CBCTs, and delivered dose for these was calculated using both the adaptive plan, and a non-adaptive plan. Results: Target coverage for lymph nodes improved using an adaptive strategy. The full bladder strategy spared the healthy part of the bladder from a high dose. Average bowel cavity V30Gy and V40Gy significantly reduced with 60 and 69 ml, respectively (p < 0.01). Other parameters for bowel and rectum remained unchanged. Conclusions: Daily plan selection compared to a non-adaptive strategy yielded similar bladder coverage and improved coverage for lymph nodes, with a significant reduction in bowel cavity V30Gy and V40Gy only, while other sparing was limited

  2. Gene duplication and adaptive evolution of digestive proteases in Drosophila arizonae female reproductive tracts.

    Directory of Open Access Journals (Sweden)

    Erin S Kelleher

    2007-08-01

    Full Text Available It frequently has been postulated that intersexual coevolution between the male ejaculate and the female reproductive tract is a driving force in the rapid evolution of reproductive proteins. The dearth of research on female tracts, however, presents a major obstacle to empirical tests of this hypothesis. Here, we employ a comparative EST approach to identify 241 candidate female reproductive proteins in Drosophila arizonae, a repleta group species in which physiological ejaculate-female coevolution has been documented. Thirty-one of these proteins exhibit elevated amino acid substitution rates, making them candidates for molecular coevolution with the male ejaculate. Strikingly, we also discovered 12 unique digestive proteases whose expression is specific to the D. arizonae lower female reproductive tract. These enzymes belong to classes most commonly found in the gastrointestinal tracts of a diverse array of organisms. We show that these proteases are associated with recent, lineage-specific gene duplications in the Drosophila repleta species group, and exhibit strong signatures of positive selection. Observation of adaptive evolution in several female reproductive tract proteins indicates they are active players in the evolution of reproductive tract interactions. Additionally, pervasive gene duplication, adaptive evolution, and rapid acquisition of a novel digestive function by the female reproductive tract points to a novel coevolutionary mechanism of ejaculate-female interaction.

  3. Adaptive evolution of mitochondrial energy metabolism genes associated with increased energy demand in flying insects.

    Science.gov (United States)

    Yang, Yunxia; Xu, Shixia; Xu, Junxiao; Guo, Yan; Yang, Guang

    2014-01-01

    Insects are unique among invertebrates for their ability to fly, which raises intriguing questions about how energy metabolism in insects evolved and changed along with flight. Although physiological studies indicated that energy consumption differs between flying and non-flying insects, the evolution of molecular energy metabolism mechanisms in insects remains largely unexplored. Considering that about 95% of adenosine triphosphate (ATP) is supplied by mitochondria via oxidative phosphorylation, we examined 13 mitochondrial protein-encoding genes to test whether adaptive evolution of energy metabolism-related genes occurred in insects. The analyses demonstrated that mitochondrial DNA protein-encoding genes are subject to positive selection from the last common ancestor of Pterygota, which evolved primitive flight ability. Positive selection was also found in insects with flight ability, whereas no significant sign of selection was found in flightless insects where the wings had degenerated. In addition, significant positive selection was also identified in the last common ancestor of Neoptera, which changed its flight mode from direct to indirect. Interestingly, detection of more positively selected genes in indirect flight rather than direct flight insects suggested a stronger selective pressure in insects having higher energy consumption. In conclusion, mitochondrial protein-encoding genes involved in energy metabolism were targets of adaptive evolution in response to increased energy demands that arose during the evolution of flight ability in insects.

  4. Chewing on the trees: Constraints and adaptation in the evolution of the primate mandible.

    Science.gov (United States)

    Meloro, Carlo; Cáceres, Nilton Carlos; Carotenuto, Francesco; Sponchiado, Jonas; Melo, Geruza Leal; Passaro, Federico; Raia, Pasquale

    2015-07-01

    Chewing on different food types is a demanding biological function. The classic assumption in studying the shape of feeding apparatuses is that animals are what they eat, meaning that adaptation to different food items accounts for most of their interspecific variation. Yet, a growing body of evidence points against this concept. We use the primate mandible as a model structure to investigate the complex interplay among shape, size, diet, and phylogeny. We find a weak but significant impact of diet on mandible shape variation in primates as a whole but not in anthropoids and catarrhines as tested in isolation. These clades mainly exhibit allometric shape changes, which are unrelated to diet. Diet is an important factor in the diversification of strepsirrhines and platyrrhines and a phylogenetic signal is detected in all primate clades. Peaks in morphological disparity occur during the Oligocene (between 37 and 25 Ma) supporting the notion that an adaptive radiation characterized the evolution of South American monkeys. In all primate clades, the evolution of mandible size is faster than its shape pointing to a strong effect of allometry on ecomorphological diversification in this group. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  5. Analysis of Adaptive Evolution in Lyssavirus Genomes Reveals Pervasive Diversifying Selection during Species Diversification

    Directory of Open Access Journals (Sweden)

    Carolina M. Voloch

    2014-11-01

    Full Text Available Lyssavirus is a diverse genus of viruses that infect a variety of mammalian hosts, typically causing encephalitis. The evolution of this lineage, particularly the rabies virus, has been a focus of research because of the extensive occurrence of cross-species transmission, and the distinctive geographical patterns present throughout the diversification of these viruses. Although numerous studies have examined pattern-related questions concerning Lyssavirus evolution, analyses of the evolutionary processes acting on Lyssavirus diversification are scarce. To clarify the relevance of positive natural selection in Lyssavirus diversification, we conducted a comprehensive scan for episodic diversifying selection across all lineages and codon sites of the five coding regions in lyssavirus genomes. Although the genomes of these viruses are generally conserved, the glycoprotein (G, RNA-dependent RNA polymerase (L and polymerase (P genes were frequently targets of adaptive evolution during the diversification of the genus. Adaptive evolution is particularly manifest in the glycoprotein gene, which was inferred to have experienced the highest density of positively selected codon sites along branches. Substitutions in the L gene were found to be associated with the early diversification of phylogroups. A comparison between the number of positively selected sites inferred along the branches of RABV population branches and Lyssavirus intespecies branches suggested that the occurrence of positive selection was similar on the five coding regions of the genome in both groups.

  6. Analysis of adaptive evolution in Lyssavirus genomes reveals pervasive diversifying selection during species diversification.

    Science.gov (United States)

    Voloch, Carolina M; Capellão, Renata T; Mello, Beatriz; Schrago, Carlos G

    2014-11-19

    Lyssavirus is a diverse genus of viruses that infect a variety of mammalian hosts, typically causing encephalitis. The evolution of this lineage, particularly the rabies virus, has been a focus of research because of the extensive occurrence of cross-species transmission, and the distinctive geographical patterns present throughout the diversification of these viruses. Although numerous studies have examined pattern-related questions concerning Lyssavirus evolution, analyses of the evolutionary processes acting on Lyssavirus diversification are scarce. To clarify the relevance of positive natural selection in Lyssavirus diversification, we conducted a comprehensive scan for episodic diversifying selection across all lineages and codon sites of the five coding regions in lyssavirus genomes. Although the genomes of these viruses are generally conserved, the glycoprotein (G), RNA-dependent RNA polymerase (L) and polymerase (P) genes were frequently targets of adaptive evolution during the diversification of the genus. Adaptive evolution is particularly manifest in the glycoprotein gene, which was inferred to have experienced the highest density of positively selected codon sites along branches. Substitutions in the L gene were found to be associated with the early diversification of phylogroups. A comparison between the number of positively selected sites inferred along the branches of RABV population branches and Lyssavirus intespecies branches suggested that the occurrence of positive selection was similar on the five coding regions of the genome in both groups.

  7. On Adaptive Extended Different Life Cycle of Product Design Strategy

    Science.gov (United States)

    Wenwen, Jiang; Zhibin, Xie

    The article uses research ways of following the whole lifespan of product and enterprise's development course to research strategy of company's product design and development. It announces enterprises of different nature, enterprises at different developing stage will adopt different mode strategy. It also announces close causality between development course of company and central technology and product. The result indicated in different developing stages such as company development period, crisis predicament period, lasting steadies period, improving by payback period, issues steadies secondary period, declining go and live period, enterprise should pursue different mode product tactics of research and development such as shrinking strategy, consolidating strategy, innovation keeping forging ahead strategy. Enterprise should break regular management mode to introduce different research and development mode to promote enterprise's competitiveness effectively.

  8. Adaptive evolution of body size subject to indirect effect in trophic cascade system.

    Science.gov (United States)

    Wang, Xin; Fan, Meng; Hao, Lina

    2017-09-01

    Trophic cascades represent a classic example of indirect effect and are wide-spread in nature. Their ecological impact are well established, but the evolutionary consequences have received even less theoretical attention. We theoretically and numerically investigate the trait (i.e., body size of consumer) evolution in response to indirect effect in a trophic cascade system. By applying the quantitative trait evolutionary theory and the adaptive dynamic theory, we formulate and explore two different types of eco-evolutionary resource-consumer-predator trophic cascade model. First, an eco-evolutionary model incorporating the rapid evolution is formulated to investigate the effect of rapid evolution of the consumer's body size, and to explore the impact of density-mediate indirect effect on the population dynamics and trait dynamics. Next, by employing the adaptive dynamic theory, a long-term evolutionary model of consumer body size is formulated to evaluate the effect of long-term evolution on the population dynamics and the effect of trait-mediate indirect effect. Those models admit rich dynamics that has not been observed yet in empirical studies. It is found that, both in the trait-mediated and density-mediated system, the body size of consumer in predator-consumer-resource interaction (indirect effect) evolves smaller than that in consumer-resource and predator-consumer interaction (direct effect). Moreover, in the density-mediated system, we found that the evolution of consumer body size contributes to avoiding consumer extinction (i.e., evolutionary rescue). The trait-mediate and density-mediate effects may produce opposite evolutionary response. This study suggests that the trophic cascade indirect effect affects consumer evolution, highlights a more comprehensive mechanistic understanding of the intricate interplay between ecological and evolutionary force. The modeling approaches provide avenue for study on indirect effects from an evolutionary perspective

  9. Improvisation as an adaptive strategy for occupational therapy practice.

    Science.gov (United States)

    Krusen, Nancy E

    2012-01-01

    ABSTRACT As health care environments become increasingly complex, practitioners must develop new adaptive skills to master practice. The idea of using theatrical improvisation (improv) in health care is relatively new. Occupational therapy students were taught a module of improvisational techniques as part of an academic seminar, learning improvisation rules, and enacting solutions to typical daily professional challenges. The purpose of this article is to recommend improvisational techniques as an adaptive skill to effectively blend art and science for occupational therapy practice in fast-paced and unpredictable health care environments.

  10. Adaptation and evolution in marine environments. Vol. 2. The impacts of global change on biodiversity

    Energy Technology Data Exchange (ETDEWEB)

    Verde, Cinzia; Di Prisco, Guido (eds.) [CNR, Napoli (Italy). Inst. of Protein Biochemistry

    2013-02-01

    Offers a regionally focussed approach. Describes research on adaptive evolution. State-of-the-art content. The second volume of ''Adaptation and Evolution in Marine Environments - The Impacts of Global Change on Biodiversity'' from the series ''From Pole to Pole'' integrates the marine biology contribution of the first tome to the IPY 2007-2009, presenting overviews of organisms (from bacteria and ciliates to higher vertebrates) thriving on polar continental shelves, slopes and deep sea. The speed and extent of warming in the Arctic and in regions of Antarctica (the Peninsula, at the present) are greater than elsewhere. Changes impact several parameters, in particular the extent of sea ice; organisms, ecosystems and communities that became finely adapted to increasing cold in the course of millions of years are now becoming vulnerable, and biodiversity is threatened. Investigating evolutionary adaptations helps to foresee the impact of changes in temperate areas, highlighting the invaluable contribution of polar marine research to present and future outcomes of the IPY in the Earth system scenario.

  11. Evolution and Adaptation of Wild Emmer Wheat Populations to Biotic and Abiotic Stresses.

    Science.gov (United States)

    Huang, Lin; Raats, Dina; Sela, Hanan; Klymiuk, Valentina; Lidzbarsky, Gabriel; Feng, Lihua; Krugman, Tamar; Fahima, Tzion

    2016-08-04

    The genetic bottlenecks associated with plant domestication and subsequent selection in man-made agroecosystems have limited the genetic diversity of modern crops and increased their vulnerability to environmental stresses. Wild emmer wheat, the tetraploid progenitor of domesticated wheat, distributed along a wide range of ecogeographical conditions in the Fertile Crescent, has valuable "left behind" adaptive diversity to multiple diseases and environmental stresses. The biotic and abiotic stress responses are conferred by series of genes and quantitative trait loci (QTLs) that control complex resistance pathways. The study of genetic diversity, genomic organization, expression profiles, protein structure and function of biotic and abiotic stress-resistance genes, and QTLs could shed light on the evolutionary history and adaptation mechanisms of wild emmer populations for their natural habitats. The continuous evolution and adaptation of wild emmer to the changing environment provide novel solutions that can contribute to safeguarding food for the rapidly growing human population.

  12. Adaptive evolution of the mitochondrial ND6 gene in the domestic horse.

    Science.gov (United States)

    Ning, T; Xiao, H; Li, J; Hua, S; Zhang, Y P

    2010-01-26

    Mitochondria play a crucial role in energy metabolism through oxidative phosphorylation. Organisms living at high altitudes are potentially influenced by oxygen deficits and cold temperatures. The severe environmental conditions can impact on metabolism and direct selection of mitochondrial DNA. As a wide-ranging animal, the domestic horse (Equus caballus) has developed various morphological and physiological characteristics for adapting to different altitudes. Thus, this is a good species for studying adaption to high altitudes at a molecular level. We sequenced the complete NADH dehydrogenase 6 gene (ND6) of 509 horses from 24 sampling locations. By comparative analysis of three horse populations living at different altitudes (>2200 m, 1200-1700 m, and horses was found distributed on the selected branches. We conclude that the high-altitude environment has directed adaptive evolution of the mitochondrial ND6 gene in the plateau horse.

  13. Land use and climate change adaptation strategies in Kenya

    NARCIS (Netherlands)

    Adimo, A.O.; Njoroge, J.B.; Claessens, L.F.G.; Wamocho, L.S.

    2012-01-01

    Climate variability and change mitigation and adaptation policies need to prioritize land users needs at local level because it is at this level that impact is felt most. In order to address the challenge of socio-economic and unique regional geographical setting, a customized methodological

  14. Organic Farming as a Strategy for Climate Change Adaptation and ...

    African Journals Online (AJOL)

    For climate change adaptation, OF systems have a strong potential for building resilient food systems through farm diversification and building soil fertility with organic matter. In developing countries, OF offers alternatives to energy-intensive production inputs such as synthetic fertilizers which are limited for poor rural ...

  15. Evolving institutional and policy frameworks to support adaptation strategies

    Science.gov (United States)

    Dave Cleaves

    2014-01-01

    Given the consequences and opportunities of the Anthropocene, what is our underlying theory or vision of successful adaptation? This essay discusses the building blocks of this theory, and how will we translate this theory into guiding principles for management and policy.

  16. Support Fund for Local Adaptation Strategies | IDRC - International ...

    International Development Research Centre (IDRC) Digital Library (Canada)

    This project seeks to strengthen the leadership and technical and organizational capacity of grassroots communities in the area of adaptation to climate change. It will do so by putting in place a process for selecting pilot projects, identifying team needs in terms of capacity building, contracting providers of (public or private) ...

  17. Accelerated evolution of innate immunity proteins in social insects: adaptive evolution or relaxed constraint?

    Science.gov (United States)

    Harpur, Brock A; Zayed, Amro

    2013-07-01

    The genomes of eusocial insects have a reduced complement of immune genes-an unusual finding considering that sociality provides ideal conditions for disease transmission. The following three hypotheses have been invoked to explain this finding: 1) social insects are attacked by fewer pathogens, 2) social insects have effective behavioral or 3) novel molecular mechanisms for combating pathogens. At the molecular level, these hypotheses predict that canonical innate immune pathways experience a relaxation of selective constraint. A recent study of several innate immune genes in ants and bees showed a pattern of accelerated amino acid evolution, which is consistent with either positive selection or a relaxation of constraint. We studied the population genetics of innate immune genes in the honey bee Apis mellifera by partially sequencing 13 genes from the bee's Toll pathway (∼10.5 kb) and 20 randomly chosen genes (∼16.5 kb) sequenced in 43 diploid workers. Relative to the random gene set, Toll pathway genes had significantly higher levels of amino acid replacement mutations segregating within A. mellifera and fixed between A. mellifera and A. cerana. However, levels of diversity and divergence at synonymous sites did not differ between the two gene sets. Although we detect strong signs of balancing selection on the pathogen recognition gene pgrp-sa, many of the genes in the Toll pathway show signatures of relaxed selective constraint. These results are consistent with the reduced complement of innate immune genes found in social insects and support the hypothesis that some aspect of eusociality renders canonical innate immunity superfluous.

  18. Mainstreaming climate change adaptation strategies into New York State Department of Transportation's operations : final report.

    Science.gov (United States)

    2011-10-31

    This study identifies climate change adaptation strategies and recommends ways of mainstreaming them into planned actions, including legislation, policies, programs and projects in all areas and at all levels within the New York State Department of T...

  19. Mainstreaming climate change adaptation strategies into New York State Department of Transportation's operations.

    Science.gov (United States)

    2011-10-31

    This study identifies climate change adaptation strategies and recommends ways of mainstreaming them into planned actions, including legislation, policies, programs and projects in all areas and at all levels within the New York State Department of T...

  20. Make way for the climate. National adaptation strategy. The policy paper

    International Nuclear Information System (INIS)

    2007-11-01

    The policy paper is a background document of the interdepartmental memorandum 'Make way for climate', in which the outline is described for a national strategy for adaptation to the consequences of climate change. [mk] [nl

  1. Functional evolution of leptin of Ochotona curzoniae in adaptive thermogenesis driven by cold environmental stress.

    Directory of Open Access Journals (Sweden)

    Jie Yang

    Full Text Available BACKGROUND: Environmental stress can accelerate the directional selection and evolutionary rate of specific stress-response proteins to bring about new or altered functions, enhancing an organism's fitness to challenging environments. Plateau pika (Ochotona curzoniae, an endemic and keystone species on Qinghai-Tibetan Plateau, is a high hypoxia and low temperature tolerant mammal with high resting metabolic rate and non-shivering thermogenesis to cope in this harsh plateau environment. Leptin is a key hormone related to how these animals regulate energy homeostasis. Previous molecular evolutionary analysis helped to generate the hypothesis that adaptive evolution of plateau pika leptin may be driven by cold stress. METHODOLOGY/PRINCIPAL FINDINGS: To test the hypothesis, recombinant pika leptin was first purified. The thermogenic characteristics of C57BL/6J mice injected with pika leptin under warm (23±1°C and cold (5±1°C acclimation is investigated. Expression levels of genes regulating adaptive thermogenesis in brown adipose tissue and the hypothalamus are compared between pika leptin and human leptin treatment, suggesting that pika leptin has adaptively and functionally evolved. Our results show that pika leptin regulates energy homeostasis via reduced food intake and increased energy expenditure under both warm and cold conditions. Compared with human leptin, pika leptin demonstrates a superior induced capacity for adaptive thermogenesis, which is reflected in a more enhanced β-oxidation, mitochondrial biogenesis and heat production. Moreover, leptin treatment combined with cold stimulation has a significant synergistic effect on adaptive thermogenesis, more so than is observed with a single cold exposure or single leptin treatment. CONCLUSIONS/SIGNIFICANCE: These findings support the hypothesis that cold stress has driven the functional evolution of plateau pika leptin as an ecological adaptation to the Qinghai-Tibetan Plateau.

  2. adaptation strategies of airline travel agencies to the dynamics of ...

    African Journals Online (AJOL)

    Bawa et al.

    strategies airline travel agencies adopt to remain in business. Data for this paper was ... that in 2013, travel and tourism's total contribution to the global economy rose to ... reality of today's tourism industry as it has penetrated the decision.

  3. Climate Change Mitigation and Adaptation Strategies Used by ...

    African Journals Online (AJOL)

    E M IGBOKWE

    This study examined the strategies employed by farmers to mitigate the effects of .... development targets like Nigeria's aspiration to be among the twenty best performing economies of .... structured interview schedule was used to collect data.

  4. Adaptive radiation with regard to nutrient sequestration strategies in the carnivorous plants of the genus Nepenthes

    OpenAIRE

    Pavlovič, Andrej

    2012-01-01

    Carnivorous pitcher plants of the genus Nepenthes have evolved a great diversity of pitcher morphologies. Selective pressures for maximizing nutrient uptake have driven speciation and diversification of the genus in a process known as adaptive radiation. This leads to the evolution of pitchers adapted to specific and often bizarre source of nutrients, which are not strictly animal-derived. One example is Nepenthes ampullaria with unusual growth pattern and pitcher morphology what enables the ...

  5. Hybrid Strategies for Link Adaptation Exploiting Several Degrees of Freedom in OFDM Based Broadband Wireless Systems

    DEFF Research Database (Denmark)

    Das, Suvra S.; Rahman, Muhammad Imadur; Wang, Yuanye

    2007-01-01

    In orthogonal frequency division multiplexing (OFDM) systems, there are several degrees of freedom in time and frequency domain, such as, sub-band size, forward error control coding (FEC) rate, modulation order, power level, modulation adaptation interval, coding rate adaptation interval and powe...... of the link parameters based on the channel conditions would lead to highly complex systems with high overhead. Hybrid strategies to vary the adaptation rates to tradeoff achievable efficiency and complexity are presented in this work....

  6. Adaptation and Validation of the Teacher Emotional Labour Strategy Scale in China

    Science.gov (United States)

    Yin, Hongbiao

    2012-01-01

    The present study reports the adaptation and validation of the Teacher Emotional Labour Strategy Scale (TELSS) as tested on samples of 633 Beijing teachers and 648 Chongqing teachers in Chinese mainland. Results show that the 13-item TELSS adapted for this study had good internal consistency on three subscales which measure three types of teacher…

  7. Upscaling the Impacts of Climate Change in Different Sectors and Adaptation Strategies

    DEFF Research Database (Denmark)

    Bouwer, Laurens; Capriolo, Alessio; Chiabai, Aline

    2018-01-01

    This chapter aims to provide up-to-date quantitative estimates of the costs and benefits related to adaptation strategies for different sectors in Europe. This is done by critically evaluating modeling frameworks and contexts applied to adaptation and by describing new developments achieved...

  8. Phylogeny and adaptive evolution of the brain-development gene microcephalin (MCPH1 in cetaceans

    Directory of Open Access Journals (Sweden)

    Montgomery Stephen H

    2011-04-01

    Full Text Available Abstract Background Representatives of Cetacea have the greatest absolute brain size among animals, and the largest relative brain size aside from humans. Despite this, genes implicated in the evolution of large brain size in primates have yet to be surveyed in cetaceans. Results We sequenced ~1240 basepairs of the brain development gene microcephalin (MCPH1 in 38 cetacean species. Alignments of these data and a published complete sequence from Tursiops truncatus with primate MCPH1 were utilized in phylogenetic analyses and to estimate ω (rate of nonsynonymous substitution/rate of synonymous substitution using site and branch models of molecular evolution. We also tested the hypothesis that selection on MCPH1 was correlated with brain size in cetaceans using a continuous regression analysis that accounted for phylogenetic history. Our analyses revealed widespread signals of adaptive evolution in the MCPH1 of Cetacea and in other subclades of Mammalia, however, there was not a significant positive association between ω and brain size within Cetacea. Conclusion In conjunction with a recent study of Primates, we find no evidence to support an association between MCPH1 evolution and the evolution of brain size in highly encephalized mammalian species. Our finding of significant positive selection in MCPH1 may be linked to other functions of the gene.

  9. Assessing Strategies for Urban Climate Change Adaptation: The Case of Six Metropolitan Cities in South Korea

    Directory of Open Access Journals (Sweden)

    Jae-Seung Lee

    2018-06-01

    Full Text Available As interest in climate change adaptation grows, an increasing number of national and local governments are developing adaptation strategies. This study assesses the strategies for urban climate change adaptation of municipal governments in South Korea. The adaptation plans and budget expenditures of six metropolitan cities in South Korea were compared, based on the Implementation Plan for Climate Change Adaptation Strategy (IPCCAS 2012–2016 and annual expenditure reports of each city. The results show that the actual implementation of these adaptation programs varied vis-à-vis the original plans, in terms of the level of overall expenditure and sector-specific expenditure. The following findings were drawn from the analysis: First, in most cases, the highest adaptation priorities were disaster/infrastructure, water management, and the health sector. Second, actual expenditure on climate change adaptation programs was smaller than the planned budget in the IPCCAS. Third, the prioritized sectors matched for planning and implementation in Seoul, Daegu, Daejeon, and Incheon, but not in Busan and Ulsan. Fourth, the adaptation programs of South Korean metropolitan cities do not seem to have been well-tailored to each case.

  10. Strategies in edge plasma simulation using adaptive dynamic nodalization techniques

    International Nuclear Information System (INIS)

    Kainz, A.; Weimann, G.; Kamelander, G.

    2003-01-01

    A wide span of steady-state and transient edge plasma processes simulation problems require accurate discretization techniques and can then be treated with Finite Element (FE) and Finite Volume (FV) methods. The software used here to meet these meshing requirements is a 2D finite element grid generator. It allows to produce adaptive unstructured grids taking into consideration the flux surface characteristics. To comply with the common mesh handling features of FE/FV packages, some options have been added to the basic generation tool. These enhancements include quadrilateral meshes without non-regular transition elements obtained by substituting them by transition constructions consisting of regular quadrilateral elements. Furthermore triangular grids can be created with one edge parallel to the magnetic field and modified by the basic adaptation/realignment techniques. Enhanced code operation properties and processing capabilities are expected. (author)

  11. Resilience, human agency and climate change adaptation strategies in the Arctic

    DEFF Research Database (Denmark)

    Sejersen, Frank

    2009-01-01

    and work with a number of barriers for resilience. The objective of the article is first to address the position of institutional barriers in the studies and strategies. Second the article analyses the role human agency is ascribed in proposed strategies and projects in Nunavut and Greenland. With a focus......  In the Arctic, indigenous peoples, researchers and governments are working to develop climate change adaptation strategies due to the rapid changes in sea ice extent, weather conditions and in the ecosystem as such. These strategies are often based on specific perceptions of vulnerability...... on institutions and human agency the question is not only ‘how do people manage to adapt?' but moreover ‘what constrains people in pursuing a given adaptation strategy?' The article introduces the concept of double agency which stresses two different aspects of human agency that can be used to understand...

  12. An analysis of climatic impacts and adaptation strategies in Tanzania

    CSIR Research Space (South Africa)

    Ojoyi, MM

    2015-03-01

    Full Text Available region of Tanzania. Climate change is a vital issue of global concern. Design/methodology/approach - Rain fall data trends collected from different meteorological stations in the region were useful in assessment of climate variability and change... also did not take into consideration institutional arrangements required to successfully implement national adaptation programmes to climate change. Finally, it is important to remember that peoples’ perceptions determine the social mental picture...

  13. Understanding International Product Strategy in Multinational Corporations through New Product Development Approaches and Evolution

    OpenAIRE

    Liu, Yang; Shi, Yongjiang

    2017-01-01

    International product strategy regarding global standardisation and local adaptation is one of the challenges faced by multinational corporations (MNCs). Studies in this area have tested the antecedents and consequences of standardisation/adaptation, but lack a new product development (NPD) perspective. In this study, we explore how product standardisation/adaptation is determined in the NPD context. Through a qualitative case study of four MNCs, we found three NPD approaches: multi-local, ad...

  14. How climate compatible are livelihood adaptation strategies and development programs in rural Indonesia?

    Directory of Open Access Journals (Sweden)

    R.M. Wise

    2016-01-01

    Full Text Available Achieving climate compatible development (CCD is a necessity in developing countries, but there are few examples of requisite planning processes, or manifestations of CCD. This paper presents a multi-stakeholder, participatory planning process designed to screen and prioritise rural livelihood adaptation strategies against nine CCD criteria. The process also integrated three principles of adaptation pathways: interventions should be (1 ‘no regrets’ and maintain reversibility to avoid mal-adaptation; (2 address both proximate and underlying systemic drivers of community vulnerability; and (3 linked across spatial scales and jurisdictional levels to promote coordination. Using examples of two rural sub-districts in Indonesia, we demonstrate the process and resulting CCD strategies. Priority strategies varied between the sub-districts but all reflected standard development interventions: water management, intensification or diversification of agriculture and aquaculture, education, health, food security and skills-building for communities. Strategies delivered co-benefits for human development and ecosystem services and hence adaptive capacity, but greenhouse mitigation co-benefits were less significant. Actions to deliver the strategies’ objectives were screened for reversibility, and a minority were potentially mal-adaptive (i.e. path dependent, disproportionately burdening the most vulnerable, reducing incentives to adapt, or increasing greenhouse gas emissions yet highly feasible. These related to infrastructure, which paradoxically is necessary to deliver ‘soft’ adaptation benefits (i.e. road access to health services. Only a small minority of transformative strategies addressed the systemic (i.e. institutional and political drivers of vulnerability. Strategies were well-matched by development programs, suggesting that current interventions mirror CCD. However, development programs tackled fewer systemic drivers, were poorly

  15. Cultural adaptation of preschool PATHS (Promoting Alternative Thinking Strategies) curriculum for Pakistani children.

    Science.gov (United States)

    Inam, Ayesha; Tariq, Pervaiz N; Zaman, Sahira

    2015-06-01

    Cultural adaptation of evidence-based programmes has gained importance primarily owing to its perceived impact on the established effectiveness of a programme. To date, many researchers have proposed different frameworks for systematic adaptation process. This article presents the cultural adaptation of preschool Promoting Alternative Thinking Strategies (PATHS) curriculum for Pakistani children using the heuristic framework of adaptation (Barrera & Castro, 2006). The study was completed in four steps: information gathering, preliminary adaptation design, preliminary adaptation test and adaptation refinement. Feedbacks on programme content suggested universality of the core programme components. Suggested changes were mostly surface structure: language, presentation of materials, conceptual equivalence of concepts, training needs of implementation staff and frequency of programme delivery. In-depth analysis was done to acquire cultural equivalence. Pilot testing of the outcome measures showed strong internal consistency. The results were further discussed with reference to similar work undertaken in other cultures. © 2014 International Union of Psychological Science.

  16. Natural Selection Causes Adaptive Genetic Resistance in Wild Emmer Wheat against Powdery Mildew at ?Evolution Canyon? Microsite, Mt. Carmel, Israel

    OpenAIRE

    Yin, Huayan; Ben-Abu, Yuval; Wang, Hongwei; Li, Anfei; Nevo, Eviatar; Kong, Lingrang

    2015-01-01

    Background ?Evolution Canyon? (ECI) at Lower Nahal Oren, Mount Carmel, Israel, is an optimal natural microscale model for unraveling evolution in action highlighting the basic evolutionary processes of adaptation and speciation. A major model organism in ECI is wild emmer, Triticum dicoccoides, the progenitor of cultivated wheat, which displays dramatic interslope adaptive and speciational divergence on the tropical-xeric ?African? slope (AS) and the temperate-mesic ?European? slope (ES), sep...

  17. Farmers’ Adaptation Strategies to Climate Change and Their Implications in the Zou Department of South Benin

    Directory of Open Access Journals (Sweden)

    Adégnandjou Mahouna Roland Fadina

    2018-01-01

    Full Text Available Climate change is a global phenomenon. Its impact on agricultural activities in developing countries has increased dramatically. Understanding how farmers perceive climate change and how they adapt to it is very important to the implementation of adequate policies for agricultural and food security. This paper aims to contribute to an understanding of farmers’ adaptation choices, determinants of the adaptation choices and the long-term implications of the adaptation choices. Data were collected from 120 respondents in the Zou Department of Benin. A binary logit model was used to analyze the factors influencing household decisions to adapt to climate change. Multinomial logistic regression analysis was estimated to analyze the factors influencing households’ choice of adaptation strategies to climate change. The results show that farmers have a developed perception of climate change. These changes are translated by rainfall disturbances (rainfall delays, early cessation, bad rainfall distribution etc., shortening of the small dry season, increasing of temperature and sometimes, violent winds. The survey reveals that Benin farmers adopt many strategies in response to climate change. These strategies include “Crop–livestock diversification and other good practices (mulching, organic fertilizer,” “Use of improved varieties, chemical fertilizers and pesticides,” “Agroforestry and perennial plantation” and “Diversification of income-generating activities.” The findings also reveal that most of the respondents use these strategies in combination. From the binary logit model, we know that “farming experience” and “educational level of household head” positively influence adaptation decisions. The result of the multinomial logit analysis shows that farming experience, educational level, farm size and gender have a significant impact on climate change adaptation strategies. Based on in-depth analysis of each strategy, we

  18. Coupling of diversification and pH adaptation during the evolution of terrestrial Thaumarchaeota

    Science.gov (United States)

    Gubry-Rangin, Cécile; Kratsch, Christina; Williams, Tom A.; McHardy, Alice C.; Embley, T. Martin; Prosser, James I.; Macqueen, Daniel J.

    2015-01-01

    The Thaumarchaeota is an abundant and ubiquitous phylum of archaea that plays a major role in the global nitrogen cycle. Previous analyses of the ammonia monooxygenase gene amoA suggest that pH is an important driver of niche specialization in these organisms. Although the ecological distribution and ecophysiology of extant Thaumarchaeota have been studied extensively, the evolutionary rise of these prokaryotes to ecological dominance in many habitats remains poorly understood. To characterize processes leading to their diversification, we investigated coevolutionary relationships between amoA, a conserved marker gene for Thaumarchaeota, and soil characteristics, by using deep sequencing and comprehensive environmental data in Bayesian comparative phylogenetics. These analyses reveal a large and rapid increase in diversification rates during early thaumarchaeotal evolution; this finding was verified by independent analyses of 16S rRNA. Our findings suggest that the entire Thaumarchaeota diversification regime was strikingly coupled to pH adaptation but less clearly correlated with several other tested environmental factors. Interestingly, the early radiation event coincided with a period of pH adaptation that enabled the terrestrial Thaumarchaeota ancestor to initially move from neutral to more acidic and alkaline conditions. In contrast to classic evolutionary models, whereby niches become rapidly filled after adaptive radiation, global diversification rates have remained stably high in Thaumarchaeota during the past 400–700 million years, suggesting an ongoing high rate of niche formation or switching for these microbes. Our study highlights the enduring importance of environmental adaptation during thaumarchaeotal evolution and, to our knowledge, is the first to link evolutionary diversification to environmental adaptation in a prokaryotic phylum. PMID:26170282

  19. Biological adaptations for functional features of language in the face of cultural evolution.

    Science.gov (United States)

    Christiansen, Morten H; Reali, Florencia; Chater, Nick

    2011-04-01

    Although there may be no true language universals, it is nonetheless possible to discern several family resemblance patterns across the languages of the world. Recent work on the cultural evolution of language indicates the source of these patterns is unlikely to be an innate universal grammar evolved through biological adaptations for arbitrary linguistic features. Instead, it has been suggested that the patterns of resemblance emerge because language has been shaped by the brain, with individual languages representing different but partially overlapping solutions to the same set of nonlinguistic constraints. Here, we use computational simulations to investigate whether biological adaptation for functional features of language, deriving from cognitive and communicative constraints, may nonetheless be possible alongside rapid cultural evolution. Specifically, we focus on the Baldwin effect as an evolutionary mechanism by which previously learned linguistic features might become innate through natural selection across many generations of language users. The results indicate that cultural evolution of language does not necessarily prevent functional features of language from becoming genetically fixed, thus potentially providing a particularly informative source of constraints on cross-linguistic resemblance patterns.

  20. Molecular evolution of the hyperthermophilic archaea of the Pyrococcus genus: analysis of adaptation to different environmental conditions

    Directory of Open Access Journals (Sweden)

    Afonnikov Dmitry A

    2009-12-01

    Full Text Available Abstract Background Prokaryotic microorganisms are able to survive and proliferate in severe environmental conditions. The increasing number of complete sequences of prokaryotic genomes has provided the basis for studying the molecular mechanisms of their adaptation at the genomic level. We apply here a computer-based approach to compare the genomes and proteomes from P. furiosus, P. horikoshii, and P. abyssi to identify features of their molecular evolution related to adaptation strategy to diverse environmental conditions. Results Phylogenetic analysis of rRNA genes from 26 Pyrococcus strains suggested that the divergence of P. furiosus, P. horikoshii and P. abyssi might have occurred from ancestral deep-sea organisms. It was demonstrated that the function of genes that have been subject to positive Darwinian selection is closely related to abiotic and biotic conditions to which archaea managed to become adapted. Divergence of the P. furiosus archaea might have been due to loss of some genes involved in cell motility or signal transduction, and/or to evolution under positive selection of the genes for translation machinery. In the course of P. horikoshii divergence, positive selection was found to operate mainly on the transcription machinery; divergence of P. abyssi was related with positive selection for the genes mainly involved in inorganic ion transport. Analysis of radical amino acid replacement rate in evolving P. furiosus, P. horikoshii and P. abyssi showed that the fixation rate was higher for radical substitutions relative to the volume of amino acid side-chain. Conclusions The current results give due credit to the important role of hydrostatic pressure as a cause of variability in the P. furiosus, P. horikoshii and P. abyssi genomes evolving in different habitats. Nevertheless, adaptation to pressure does not appear to be the sole factor ensuring adaptation to environment. For example, at the stage of the divergence of P

  1. Thermally adapted design strategy of colonial houses in Surabaya

    Science.gov (United States)

    Antaryama, I. G. N.; Ekasiwi, S. N. N.; Mappajaya, A.; Ulum, M. S.

    2018-03-01

    Colonial buildings, including houses, have been considered as a representation of climate-responsive architecture. The design was thought to be a hybrid model of Dutch and tropical architecture. It was created by way of reinventing tropical and Dutch architecture design principles, and expressed in a new form, i.e. neither resembling Dutch nor tropical building. Aside from this new image, colonial house does show good climatic responses. Previous researches on colonial house generally focus on qualitative assessment of climate performance of the building. Yet this kind of study tends to concentrate on building elements, e.g. wall, window, etc. The present study is designed to give more complete picture of architecture design strategy of the house by exploring and analysing thermal performance of colonial buildings and their related architecture design strategies. Field measurements are conducted during the dry season in several colonial building in Surabaya. Air temperature and humidity are both taken, representing internal and external thermal conditions of the building. These data are then evaluated to determine thermal performance of the house. Finally, various design strategies are examined in order to reveal their significant contributions to its thermal performance. Results of the study in Surabaya confirm findings of the previous researches that are conducted in other locations, which stated that thermal performance of the house is generally good. Passive design strategies such as mass effect and ventilation play an important role in determining performance of the building.

  2. Climate change adaptation strategies by small-scale farmers in ...

    African Journals Online (AJOL)

    Mburu

    Some of these strategies had serious adverse environmental impacts on social, economic and biophysical domains of the .... Women farmers in Peru take advantage of the knowledge inherited from ancient Peruvian .... is listed in the IUCN Red List (2010) as a near threatened species. Sand harvesting. The results show that ...

  3. Climate change adaptation strategies by small-scale farmers in ...

    African Journals Online (AJOL)

    Mburu

    Some of these strategies had serious adverse environmental impacts on social, economic and biophysical domains of the environment ..... self-help groups, establishing kitchen gardens, storing fodder and turning to goat milk as ways of ... Aquatic life poisoning by oil/fuel spills. 3. 3.3. Environmental conservation skills and.

  4. Inventing an arsenal: adaptive evolution and neofunctionalization of snake venom phospholipase A2 genes

    Directory of Open Access Journals (Sweden)

    Lynch Vincent J

    2007-01-01

    Full Text Available Abstract Background Gene duplication followed by functional divergence has long been hypothesized to be the main source of molecular novelty. Convincing examples of neofunctionalization, however, remain rare. Snake venom phospholipase A2 genes are members of large multigene families with many diverse functions, thus they are excellent models to study the emergence of novel functions after gene duplications. Results Here, I show that positive Darwinian selection and neofunctionalization is common in snake venom phospholipase A2 genes. The pattern of gene duplication and positive selection indicates that adaptive molecular evolution occurs immediately after duplication events as novel functions emerge and continues as gene families diversify and are refined. Surprisingly, adaptive evolution of group-I phospholipases in elapids is also associated with speciation events, suggesting adaptation of the phospholipase arsenal to novel prey species after niche shifts. Mapping the location of sites under positive selection onto the crystal structure of phospholipase A2 identified regions evolving under diversifying selection are located on the molecular surface and are likely protein-protein interactions sites essential for toxin functions. Conclusion These data show that increases in genomic complexity (through gene duplications can lead to phenotypic complexity (venom composition and that positive Darwinian selection is a common evolutionary force in snake venoms. Finally, regions identified under selection on the surface of phospholipase A2 enzymes are potential candidate sites for structure based antivenin design.

  5. Evolution dynamics of a model for gene duplication under adaptive conflict

    Science.gov (United States)

    Ancliff, Mark; Park, Jeong-Man

    2014-06-01

    We present and solve the dynamics of a model for gene duplication showing escape from adaptive conflict. We use a Crow-Kimura quasispecies model of evolution where the fitness landscape is a function of Hamming distances from two reference sequences, which are assumed to optimize two different gene functions, to describe the dynamics of a mixed population of individuals with single and double copies of a pleiotropic gene. The evolution equations are solved through a spin coherent state path integral, and we find two phases: one is an escape from an adaptive conflict phase, where each copy of a duplicated gene evolves toward subfunctionalization, and the other is a duplication loss of function phase, where one copy maintains its pleiotropic form and the other copy undergoes neutral mutation. The phase is determined by a competition between the fitness benefits of subfunctionalization and the greater mutational load associated with maintaining two gene copies. In the escape phase, we find a dynamics of an initial population of single gene sequences only which escape adaptive conflict through gene duplication and find that there are two time regimes: until a time t* single gene sequences dominate, and after t* double gene sequences outgrow single gene sequences. The time t* is identified as the time necessary for subfunctionalization to evolve and spread throughout the double gene sequences, and we show that there is an optimum mutation rate which minimizes this time scale.

  6. CROSS-CULTURAL EXPERIMENTS AS AN ADAPTATION STRATEGY

    Directory of Open Access Journals (Sweden)

    И И Подойницына

    2017-12-01

    Full Text Available The article considers methodological and empirical aspects of cross-cultural communica-tions under the economic and cultural globalization that determined the free movement of labor migrants around the world though this process is accompanied by certain difficulties. The authors believe that even a theoretically prepared person that knows about the influence of cultural differences on the organizational management in different countries will experience a cultural shock when working abroad. The cultural shock is a discomfort, frustration and even depression caused by getting into an unfamiliar environment. At the applied level, the authors analyze the so-called ‘cross-cultural experiments’ - attempts of an individual (a working specialist of a certain nation to test one’s strength, skills, and professional competencies in a foreign company. The authors’ sociological study of a cultural benchmarking type consisted of two stages. At the first stage, foreigners working in the capital of the Republic of Sakha (Yakutia were inter-viewed; at the second stage, the Russians working abroad, mainly in the USA, were interviewed. The migra-tion flows from China have recently intensified in Yakutia, but the overwhelming majority of labor migrants are still from West and Central Asia, mainly from Tajikistan, Kyrgyzstan, and Armenia. The foreigners working in Yakutia and Russians working abroad experience same difficulties of adaptation in a new col-lective. Friends, relatives, members of the ethnic community, but not specially trained cross-cultural coaches and mentors, help them with adaptation. Such a personnel technology as selection, recruitment and headhunt-ing works reasonably well, while other HR technologies of cross-cultural management (motivation, feedback, etc. are still lagging behind. The authors insist on introducing courses on cross-cultural adaptation in interna-tional groups both in Russia and abroad together with a system of the so

  7. Thanatosis as an adaptive male mating strategy in the nuptial gift-giving spider Pisaura mirabilis

    DEFF Research Database (Denmark)

    Hansen, Line S.; Gonzalez, Sofía F.; Toft, Søren

    2008-01-01

    Males and females often experience different optima in mating rate, which may cause evolution of female resistance to matings and male counter adaptations to increase mating rate. Males of the spider Pisaura mirabilis display a spectacular mating behavior involving a nuptial gift and thanatosis...

  8. Acculturation Strategies, Social Support, and Cross-Cultural Adaptation: A Mediation Analysis

    Science.gov (United States)

    Ng, Ting Kin; Tsang, Kwok Kuen; Lian, Yi

    2013-01-01

    Previous acculturation research has established the influences of acculturation strategies and social support on cross-cultural adaptation. The present study attempted to elaborate these direct associations by proposing that social support and the use of the integration and marginalization strategies might affect psychological adaptation…

  9. F:ACTS! : Forms for adapting to climate change through territorial strategies : the handbook

    NARCIS (Netherlands)

    Garcia, A.M.; Ónega, J.; Crecente, R.; Holst, van F.; Abts, E.; Timmermans, W.; Stolk, M.

    2014-01-01

    The F:ACTS! project contributed to generating knowledge on how to develop territorial strategies to adapt to climate change, facilitating the interchange of experience and information among its 14 partners across 8 countries. Integrated territorial strategies incorporate local diversity since they

  10. Climate change perceptions and local adaptation strategies of hazard-prone rural households in Bangladesh

    Directory of Open Access Journals (Sweden)

    G.M. Monirul Alam

    2017-01-01

    Full Text Available Adaptation is a key strategy that can alleviate the severity of climate change impacts on agriculture and food production. Adaptation strategies are unlikely to be effective without an understanding of the farmers’ perceptions of climate change. This paper explores the local knowledge of adaptation in response to the perceived impacts of climate change and climatic hazards using a survey of 380 resource-poor riverbank erosion-prone households in Bangladesh. The results indicate that the respondents’ perceptions of changes in the climate and of extreme climatic events are similar to the observed climate data. Households have recognized the impacts on their livelihood and resources, resulting in an increased sense of vulnerability. To build resilience, households have undertaken a range of farming and non-farming adaptation strategies, which vary significantly among the farming groups. The important adaptation strategies include adopting new crop varieties, changing planting time, homestead gardening, planting trees and migration. Improved access to finance and to information about appropriate strategies appears to be crucial to support adaptation processes locally and thus to enhance the resilience of vulnerable households.

  11. Key Parameters Estimation and Adaptive Warning Strategy for Rear-End Collision of Vehicle

    Directory of Open Access Journals (Sweden)

    Xiang Song

    2015-01-01

    Full Text Available The rear-end collision warning system requires reliable warning decision mechanism to adapt the actual driving situation. To overcome the shortcomings of existing warning methods, an adaptive strategy is proposed to address the practical aspects of the collision warning problem. The proposed strategy is based on the parameter-adaptive and variable-threshold approaches. First, several key parameter estimation algorithms are developed to provide more accurate and reliable information for subsequent warning method. They include a two-stage algorithm which contains a Kalman filter and a Luenberger observer for relative acceleration estimation, a Bayesian theory-based algorithm of estimating the road friction coefficient, and an artificial neural network for estimating the driver’s reaction time. Further, the variable-threshold warning method is designed to achieve the global warning decision. In the method, the safety distance is employed to judge the dangerous state. The calculation method of the safety distance in this paper can be adaptively adjusted according to the different driving conditions of the leading vehicle. Due to the real-time estimation of the key parameters and the adaptive calculation of the warning threshold, the strategy can adapt to various road and driving conditions. Finally, the proposed strategy is evaluated through simulation and field tests. The experimental results validate the feasibility and effectiveness of the proposed strategy.

  12. Nordic national climate adaptation and tourism strategies – (how) are they interlinked?

    DEFF Research Database (Denmark)

    Landauer, Mia; Goodsite, Michael Evan; Juhola, Sirkku

    2018-01-01

    , there is a need to review adaptation actions for tourism within the national adaptation framework supported by research based evidence. Next, by means of Nordic cooperation, guidance for both public and private tourism actors within and across Nordic countries can be provided. This can enhance the competitiveness......The tourism sector is affected by climate change. Nordic tourism destinations have also experienced changes, such as changing precipitation patterns, lack of snow in winter and shifts in seasons. The sector has to implement adaptation strategies but it is unclear whether the current public climate...... policy is sufficient to support considering adaptation actions. We reviewed national climate strategies of the Nordic countries from the perspectives of tourism, but excluding the transport sector. We also reviewed Nordic national tourism strategies from the perspective of climate change, particularly...

  13. Evolution of strategies to improve preclinical cardiac safety testing.

    Science.gov (United States)

    Gintant, Gary; Sager, Philip T; Stockbridge, Norman

    2016-07-01

    The early and efficient assessment of cardiac safety liabilities is essential to confidently advance novel drug candidates. This article discusses evolving mechanistically based preclinical strategies for detecting drug-induced electrophysiological and structural cardiotoxicity using in vitro human ion channel assays, human-based in silico reconstructions and human stem cell-derived cardiomyocytes. These strategies represent a paradigm shift from current approaches, which rely on simplistic in vitro assays that measure blockade of the Kv11.1 current (also known as the hERG current or IKr) and on the use of non-human cells or tissues. These new strategies have the potential to improve sensitivity and specificity in the early detection of genuine cardiotoxicity risks, thereby reducing the likelihood of mistakenly discarding viable drug candidates and speeding the progression of worthy drugs into clinical trials.

  14. Urban Planning and Climate Change: Adaptation and Mitigation Strategies

    Directory of Open Access Journals (Sweden)

    Fulvia Pinto

    2014-05-01

    Full Text Available Climate change is a current phenomenon: the temperatures rise, rainfall patterns are changing, glaciers melt and the average global sea level is rising. It is expected that these changes will continue and that the extreme weather events, such as floods and droughts, will become more frequent and intense. The impact and vulnerability factors for nature, for the economy and for our health are different, depending on the territorial, social and economic aspects. The current scientific debate is focused on the need to formulate effective policies for adaptation and mitigation to climate change. The city plays an important role in this issue: it emits the most greenhouse gas emissions (more than 60% of the world population currently lives in urban areas and the city is more exposed and vulnerable to the impacts of climate change. Urban planning and territorial governance play a crucial role in this context: the international debate on the sustainability of urban areas is increasing. It’s necessary to adapt the tools of building regulations to increase the quality of energy - environment of the cities.

  15. Analysis of the mitigation and adaptation strategies of the transport industry in the city of Mexicali

    Directory of Open Access Journals (Sweden)

    Argelia Melero Hernández

    2013-07-01

    Full Text Available The aim of this paper is to develop an analysis of mitigation and adaptation strategies in the transport sector in the city of Mexicali, Baja California, Mexico. Based on the methodology of the Programs of Action on Climate Change (PACC, we analyzed the Mexicali emissions inventory and generated a diagnosis. Once we analyzed the current situation, we studied mitigation strategies such as Bus Rapid Transit (BRT, the smog check, new importation legislation for used cars, biofuel production, the promotion of lower–emission vehicles and urban planning. On adaptation strategies vehicle recycling and the use of non–motorized transport were studied as an alternative of sustainable mobility.

  16. Adapting Knowledge Translation Strategies for Rare Rheumatic Diseases.

    Science.gov (United States)

    Cellucci, Tania; Lee, Shirley; Webster, Fiona

    2016-08-01

    Rare rheumatic diseases present unique challenges to knowledge translation (KT) researchers. There is often an urgent need to transfer knowledge from research findings into clinical practice to facilitate earlier diagnosis and better outcomes. However, existing KT frameworks have not addressed the specific considerations surrounding rare diseases for which gold standard evidence is not available. Several widely adopted models provide guidance for processes and problems associated with KT. However, they do not address issues surrounding creation or synthesis of knowledge for rare diseases. Additional problems relate to lack of awareness or experience in intended knowledge users, low motivation, and potential barriers to changing practice or policy. Strategies to address the challenges of KT for rare rheumatic diseases include considering different levels of evidence available, linking knowledge creation and transfer directly, incorporating patient and physician advocacy efforts to generate awareness of conditions, and selecting strategies to address barriers to practice or policy change.

  17. Evidence for determinism in species diversification and contingency in phenotypic evolution during adaptive radiation.

    Science.gov (United States)

    Burbrink, Frank T; Chen, Xin; Myers, Edward A; Brandley, Matthew C; Pyron, R Alexander

    2012-12-07

    Adaptive radiation (AR) theory predicts that groups sharing the same source of ecological opportunity (EO) will experience deterministic species diversification and morphological evolution. Thus, deterministic ecological and morphological evolution should be correlated with deterministic patterns in the tempo and mode of speciation for groups in similar habitats and time periods. We test this hypothesis using well-sampled phylogenies of four squamate groups that colonized the New World (NW) in the Late Oligocene. We use both standard and coalescent models to assess species diversification, as well as likelihood models to examine morphological evolution. All squamate groups show similar early pulses of speciation, as well as diversity-dependent ecological limits on clade size at a continental scale. In contrast, processes of morphological evolution are not easily predictable and do not show similar pulses of early and rapid change. Patterns of morphological and species diversification thus appear uncoupled across these groups. This indicates that the processes that drive diversification and disparification are not mechanistically linked, even among similar groups of taxa experiencing the same sources of EO. It also suggests that processes of phenotypic diversification cannot be predicted solely from the existence of an AR or knowledge of the process of diversification.

  18. Evidence for determinism in species diversification and contingency in phenotypic evolution during adaptive radiation

    Science.gov (United States)

    Burbrink, Frank T.; Chen, Xin; Myers, Edward A.; Brandley, Matthew C.; Pyron, R. Alexander

    2012-01-01

    Adaptive radiation (AR) theory predicts that groups sharing the same source of ecological opportunity (EO) will experience deterministic species diversification and morphological evolution. Thus, deterministic ecological and morphological evolution should be correlated with deterministic patterns in the tempo and mode of speciation for groups in similar habitats and time periods. We test this hypothesis using well-sampled phylogenies of four squamate groups that colonized the New World (NW) in the Late Oligocene. We use both standard and coalescent models to assess species diversification, as well as likelihood models to examine morphological evolution. All squamate groups show similar early pulses of speciation, as well as diversity-dependent ecological limits on clade size at a continental scale. In contrast, processes of morphological evolution are not easily predictable and do not show similar pulses of early and rapid change. Patterns of morphological and species diversification thus appear uncoupled across these groups. This indicates that the processes that drive diversification and disparification are not mechanistically linked, even among similar groups of taxa experiencing the same sources of EO. It also suggests that processes of phenotypic diversification cannot be predicted solely from the existence of an AR or knowledge of the process of diversification. PMID:23034709

  19. Adaptive evolution of the venom-targeted vWF protein in opossums that eat pitvipers.

    Directory of Open Access Journals (Sweden)

    Sharon A Jansa

    Full Text Available The rapid evolution of venom toxin genes is often explained as the result of a biochemical arms race between venomous animals and their prey. However, it is not clear that an arms race analogy is appropriate in this context because there is no published evidence for rapid evolution in genes that might confer toxin resistance among routinely envenomed species. Here we report such evidence from an unusual predator-prey relationship between opossums (Marsupialia: Didelphidae and pitvipers (Serpentes: Crotalinae. In particular, we found high ratios of replacement to silent substitutions in the gene encoding von Willebrand Factor (vWF, a venom-targeted hemostatic blood protein, in a clade of opossums known to eat pitvipers and to be resistant to their hemorrhagic venom. Observed amino-acid substitutions in venom-resistant opossums include changes in net charge and hydrophobicity that are hypothesized to weaken the bond between vWF and one of its toxic snake-venom ligands, the C-type lectin-like protein botrocetin. Our results provide the first example of rapid adaptive evolution in any venom-targeted molecule, and they support the notion that an evolutionary arms race might be driving the rapid evolution of snake venoms. However, in the arms race implied by our results, venomous snakes are prey, and their venom has a correspondingly defensive function in addition to its usual trophic role.

  20. The evolution of Islamic State's strategy | Solomon | Scientia Militaria ...

    African Journals Online (AJOL)

    With these funds, IS has deployed soft power – digging sewage systems and providing stipends to families – to earn the loyalty of its 'citizens'. IS has also displayed superior military strategy combining conventional military doctrine with asymmetric warfare. As IS are confronted with superior conventional forces in their ...

  1. Evolution of complex asexual reproductive strategies in jellyfish

    DEFF Research Database (Denmark)

    Schnedler-Meyer, Nicolas Azaña; Pigolotti, Simone; Mariani, Patrizio

    2018-01-01

    Many living organisms in terrestrial and aquatic ecosystems rely on multiple reproductive strategies to reduce the risk of extinction in variable environments. Examples are provided by the polyp stage of several bloom-forming jellyfish species, which can reproduce asexually using different buddin...

  2. Distinct motor strategies underlying split-belt adaptation in human walking and running.

    Science.gov (United States)

    Ogawa, Tetsuya; Kawashima, Noritaka; Obata, Hiroki; Kanosue, Kazuyuki; Nakazawa, Kimitaka

    2015-01-01

    The aim of the present study was to elucidate the adaptive and de-adaptive nature of human running on a split-belt treadmill. The degree of adaptation and de-adaptation was compared with those in walking by calculating the antero-posterior component of the ground reaction force (GRF). Adaptation to walking and running on a split-belt resulted in a prominent asymmetry in the movement pattern upon return to the normal belt condition, while the two components of the GRF showed different behaviors depending on the gaits. The anterior braking component showed prominent adaptive and de-adaptive behaviors in both gaits. The posterior propulsive component, on the other hand, exhibited such behavior only in running, while that in walking showed only short-term aftereffect (lasting less than 10 seconds) accompanied by largely reactive responses. These results demonstrate a possible difference in motor strategies (that is, the use of reactive feedback and adaptive feedforward control) by the central nervous system (CNS) for split-belt locomotor adaptation between walking and running. The present results provide basic knowledge on neural control of human walking and running as well as possible strategies for gait training in athletic and rehabilitation scenes.

  3. Distinct motor strategies underlying split-belt adaptation in human walking and running.

    Directory of Open Access Journals (Sweden)

    Tetsuya Ogawa

    Full Text Available The aim of the present study was to elucidate the adaptive and de-adaptive nature of human running on a split-belt treadmill. The degree of adaptation and de-adaptation was compared with those in walking by calculating the antero-posterior component of the ground reaction force (GRF. Adaptation to walking and running on a split-belt resulted in a prominent asymmetry in the movement pattern upon return to the normal belt condition, while the two components of the GRF showed different behaviors depending on the gaits. The anterior braking component showed prominent adaptive and de-adaptive behaviors in both gaits. The posterior propulsive component, on the other hand, exhibited such behavior only in running, while that in walking showed only short-term aftereffect (lasting less than 10 seconds accompanied by largely reactive responses. These results demonstrate a possible difference in motor strategies (that is, the use of reactive feedback and adaptive feedforward control by the central nervous system (CNS for split-belt locomotor adaptation between walking and running. The present results provide basic knowledge on neural control of human walking and running as well as possible strategies for gait training in athletic and rehabilitation scenes.

  4. Hologenomic adaptations underlying the evolution of sanguivory in the common vampire bat

    DEFF Research Database (Denmark)

    Zepeda Mendoza, M. Lisandra; Xiong, Zijun; Escalera-Zamudio, Marina

    2018-01-01

    Adaptation to specialized diets often requires modifications at both genomic and microbiome levels. We applied a hologenomic approach to the common vampire bat (Desmodus rotundus), one of the only three obligate blood-feeding (sanguivorous) mammals, to study the evolution of its complex dietary...... integrated viral elements, a dietary and phylogenetic influence on gut microbiome taxonomic and functional profiles, and that both genetic elements harbour key traits related to the nutritional (for example, vitamin and lipid shortage) and non-nutritional (for example, nitrogen waste and osmotic homeostasis...

  5. Agent Based Simulation of Group Emotions Evolution and Strategy Intervention in Extreme Events

    Directory of Open Access Journals (Sweden)

    Bo Li

    2014-01-01

    Full Text Available Agent based simulation method has become a prominent approach in computational modeling and analysis of public emergency management in social science research. The group emotions evolution, information diffusion, and collective behavior selection make extreme incidents studies a complex system problem, which requires new methods for incidents management and strategy evaluation. This paper studies the group emotion evolution and intervention strategy effectiveness using agent based simulation method. By employing a computational experimentation methodology, we construct the group emotion evolution as a complex system and test the effects of three strategies. In addition, the events-chain model is proposed to model the accumulation influence of the temporal successive events. Each strategy is examined through three simulation experiments, including two make-up scenarios and a real case study. We show how various strategies could impact the group emotion evolution in terms of the complex emergence and emotion accumulation influence in extreme events. This paper also provides an effective method of how to use agent-based simulation for the study of complex collective behavior evolution problem in extreme incidents, emergency, and security study domains.

  6. An adaptive routing strategy for packet delivery in complex networks

    International Nuclear Information System (INIS)

    Zhang, Huan; Liu, Zonghua; Tang, Ming; Hui, P.M.

    2007-01-01

    We present an efficient routing approach for delivering packets in complex networks. On delivering a message from a node to a destination, a node forwards the message to a neighbor by estimating the waiting time along the shortest path from each of its neighbors to the destination. This projected waiting time is dynamical in nature and the path through which a message is delivered would be adapted to the distribution of messages in the network. Implementing the approach on scale-free networks, we show that the present approach performs better than the shortest-path approach and another approach that takes into account of the waiting time only at the neighboring nodes. Key features in numerical results are explained by a mean field theory. The approach has the merit that messages are distributed among the nodes according to the capabilities of the nodes in handling messages

  7. Urban plant physiology: adaptation-mitigation strategies under permanent stress.

    Science.gov (United States)

    Calfapietra, Carlo; Peñuelas, Josep; Niinemets, Ülo

    2015-02-01

    Urban environments that are stressful for plant function and growth will become increasingly widespread in future. In this opinion article, we define the concept of 'urban plant physiology', which focuses on plant responses and long term adaptations to urban conditions and on the capacity of urban vegetation to mitigate environmental hazards in urbanized settings such as air and soil pollution. Use of appropriate control treatments would allow for studies in urban environments to be comparable to expensive manipulative experiments. In this opinion article, we propose to couple two approaches, based either on environmental gradients or manipulated gradients, to develop the concept of urban plant physiology for assessing how single or multiple environmental factors affect the key environmental services provided by urban forests. Copyright © 2014 Elsevier Ltd. All rights reserved.

  8. Comparative and functional genomics of the Lactococcus lactis taxon; insights into evolution and niche adaptation.

    Science.gov (United States)

    Kelleher, Philip; Bottacini, Francesca; Mahony, Jennifer; Kilcawley, Kieran N; van Sinderen, Douwe

    2017-03-29

    Lactococcus lactis is among the most widely studied lactic acid bacterial species due to its long history of safe use and economic importance to the dairy industry, where it is exploited as a starter culture in cheese production. In the current study, we report on the complete sequencing of 16 L. lactis subsp. lactis and L. lactis subsp. cremoris genomes. The chromosomal features of these 16 L. lactis strains in conjunction with 14 completely sequenced, publicly available lactococcal chromosomes were assessed with particular emphasis on discerning the L. lactis subspecies division, evolution and niche adaptation. The deduced pan-genome of L. lactis was found to be closed, indicating that the representative data sets employed for this analysis are sufficient to fully describe the genetic diversity of the taxon. Niche adaptation appears to play a significant role in governing the genetic content of each L. lactis subspecies, while (differential) genome decay and redundancy in the dairy niche is also highlighted.

  9. Institutions for adaptation to climate change: comparing national adaptation strategies in Europe

    NARCIS (Netherlands)

    Termeer, C.J.A.M.; Biesbroek, G.R.; Brink, van den M.A.

    2012-01-01

    In addition to reducing greenhouse gas emissions, societies worldwide have to cope with the potential impacts of climate change. The central question of this paper is to what extent our historically grown institutions enable actors to cope with the new challenges of climate adaptation. We present

  10. Genetic Adaptation to Salt Stress in Experimental Evolution of Desulfovibrio vulgaris Hildenborough

    Energy Technology Data Exchange (ETDEWEB)

    Zhou, Aifen; Hillesland, Kristina; He, Zhili; Joachimiak, Marcin; Zane, Grant; Dehal, Paramvir; Arkin, Adam; Stahl, David; Wall, Judy; Hazen, Terry; Zhou, Jizhong; Baidoo, Edward; Benke, Peter; Mukhopadhyay, Aindrila

    2010-05-17

    High salinity is one of the most common environmental stressors. In order to understand how environmental organisms adapt to salty environment, an experiment evolution with sulfate reducing bacteria Desulfovibrio vugaris Hildenborough was conducted. Control lines and salt-stressed lines (6 lines each) grown in minimal medium LS4D or LS4D + 100 mM NaCl were transferred for 1200 generations. The salt tolerance was tested with LS4D supplemented with 250 mM NaCl. Statistical analysis of the growth data suggested that all lines adapted to their evolutionary environment. In addition, the control lines performed better than the ancestor with faster growth rate, higher biomass yield and shorter lag phase under salty environment they did not evolve in. However, the salt-adapted lines performed better than the control lines on measures of growth rate and yield under salty environment, suggesting that the salt?evolved lines acquired mutations specific to having extra salt in LS4D. Growth data and gene transcription data suggested that populations tended to improve till 1000 generations and active mutations tended to be fixed at the stage of 1000 generations. Point mutations and insertion/deletions were identified in isolated colonies from salt-adapted and control lines via whole genome sequencing. Glu, Gln and Ala appears to be the major osmoprotectant in evolved salt-stressed line. Ongoing studies are now characterizing the contribution of specific mutations identified in the salt-evolved D. vulgaris.

  11. An evolution-based strategy for engineering allosteric regulation

    Science.gov (United States)

    Pincus, David; Resnekov, Orna; Reynolds, Kimberly A.

    2017-04-01

    Allosteric regulation provides a way to control protein activity at the time scale of milliseconds to seconds inside the cell. An ability to engineer synthetic allosteric systems would be of practical utility for the development of novel biosensors, creation of synthetic cell signaling pathways, and design of small molecule pharmaceuticals with regulatory impact. To this end, we outline a general approach—termed rational engineering of allostery at conserved hotspots (REACH)—to introduce novel regulation into a protein of interest by exploiting latent allostery that has been hard-wired by evolution into its structure. REACH entails the use of statistical coupling analysis (SCA) to identify ‘allosteric hotspots’ on protein surfaces, the development and implementation of experimental assays to test hotspots for functionality, and a toolkit of allosteric modulators to impinge on endogenous cellular circuitry. REACH can be broadly applied to rewire cellular processes to respond to novel inputs.

  12. Evolution in Clinical Knowledge Management Strategy at Intermountain Healthcare

    Science.gov (United States)

    Hulse, Nathan C.; Galland, Joel; Borsato, Emerson P.

    2012-01-01

    In this manuscript, we present an overview of the clinical knowledge management strategy at Intermountain Healthcare in support of our electronic medical record systems. Intermountain first initiated efforts in developing a centralized enterprise knowledge repository in 2001. Applications developed, areas of emphasis served, and key areas of focus are presented. We also detail historical and current areas of emphasis, in response to business needs. PMID:23304309

  13. Using a social justice and health framework to assess European climate change adaptation strategies.

    Science.gov (United States)

    Boeckmann, Melanie; Zeeb, Hajo

    2014-11-28

    Climate change puts pressure on existing health vulnerabilities through higher frequency of extreme weather events, changes in disease vector distribution or exacerbated air pollution. Climate change adaptation policies may hold potential to reduce societal inequities. We assessed the role of public health and social justice in European climate change adaptation using a three-fold approach: a document analysis, a critical discourse analysis of a subgroup of strategies, and a ranking of strategies against our social justice framework. The ranking approach favored planning that includes various adaptation types, social issues and infrastructure changes. Themes on values identified in the five subgroup documents showed that risks are perceived as contradictory, technology is viewed as savior, responsibilities need to be negotiated, and social justice is advocated by only a few countries. Of 21 strategy documents assessed overall, those from Austria, England and Sweden received the highest scores in the ranking. Our qualitative assessment showed that in European adaptation planning, progress could still be made through community involvement into adaptation decisions, consistent consideration of social and demographic determinants, and a stronger link between infrastructural adaptation and the health sector. Overall, a social justice framework can serve as an evaluation guideline for adaptation policy documents.

  14. An adaptive regularization parameter choice strategy for multispectral bioluminescence tomography

    Energy Technology Data Exchange (ETDEWEB)

    Feng Jinchao; Qin Chenghu; Jia Kebin; Han Dong; Liu Kai; Zhu Shouping; Yang Xin; Tian Jie [Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, P. O. Box 2728, Beijing 100190 (China); College of Electronic Information and Control Engineering, Beijing University of Technology, Beijing 100124 (China); Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, P. O. Box 2728, Beijing 100190 (China); Medical Image Processing Group, Institute of Automation, Chinese Academy of Sciences, P. O. Box 2728, Beijing 100190 (China) and School of Life Sciences and Technology, Xidian University, Xi' an 710071 (China)

    2011-11-15

    Purpose: Bioluminescence tomography (BLT) provides an effective tool for monitoring physiological and pathological activities in vivo. However, the measured data in bioluminescence imaging are corrupted by noise. Therefore, regularization methods are commonly used to find a regularized solution. Nevertheless, for the quality of the reconstructed bioluminescent source obtained by regularization methods, the choice of the regularization parameters is crucial. To date, the selection of regularization parameters remains challenging. With regards to the above problems, the authors proposed a BLT reconstruction algorithm with an adaptive parameter choice rule. Methods: The proposed reconstruction algorithm uses a diffusion equation for modeling the bioluminescent photon transport. The diffusion equation is solved with a finite element method. Computed tomography (CT) images provide anatomical information regarding the geometry of the small animal and its internal organs. To reduce the ill-posedness of BLT, spectral information and the optimal permissible source region are employed. Then, the relationship between the unknown source distribution and multiview and multispectral boundary measurements is established based on the finite element method and the optimal permissible source region. Since the measured data are noisy, the BLT reconstruction is formulated as l{sub 2} data fidelity and a general regularization term. When choosing the regularization parameters for BLT, an efficient model function approach is proposed, which does not require knowledge of the noise level. This approach only requests the computation of the residual and regularized solution norm. With this knowledge, we construct the model function to approximate the objective function, and the regularization parameter is updated iteratively. Results: First, the micro-CT based mouse phantom was used for simulation verification. Simulation experiments were used to illustrate why multispectral data were used

  15. Coping and adaptive strategies of traumatic brain injury survivors and primary caregivers.

    Science.gov (United States)

    Adams, Deana; Dahdah, Marie

    2016-06-27

    Qualitative research methods allowed the investigator to contribute to the development of new theories and to examine change in processes over time, which added rich detail to existing knowledge of the use of coping and adaptive strategies by traumatic brain injury survivors and their primary caregivers (Ponsford, Sloan, & Snow, 2013). The advantages of phenomenological study were that it allows flexibility to explore and understand meanings attached by people to well-studied concepts such as coping, resiliency, and adaptation or compensation. Phenomenological study was sensitive to contextual factors. It also permitted the study of in-depth dynamics of coping and adaptive strategies of TBI survivors and primary caregivers, while understanding the social and psychological implications of the phenomenon. To explore the needs and deficits of adult traumatic brain injury (TBI) survivors and primary caregivers; and to identify their self-initiated coping and adaptive strategies. Significant to this study was the development of coping and adaptive strategies by the participants after their discharge from inpatient and rehabilitation treatment. The compensatory skills taught in treatment settings did not transfer to the home environment. Therefore, these strategies developed independently from previous treatment recommendations contributed to the development of theory related to rehabilitation and counseling. Distinctive to this study was the similarity of coping and adaptive strategies developed from both mild and severe traumatic brain injury survivors. This study consisted of eleven with TBI and six primary caregivers (N = 17), who participated in a series of semi-structured interviews aimed at discovering the coping and adaptive strategies utilized in dealing with the effects of brain injury. A Qualitative Phenomenological design was employed. Patience and understanding, support, and professional help were identified by TBI survivors and caregivers as being their

  16. Influence of smallholder farmers’ perceptions on adaptation strategies to climate change and policy implications in Zimbabwe

    Directory of Open Access Journals (Sweden)

    Jiri Obert

    2017-01-01

    Full Text Available Smallholder agricultural production is largely affected by climate change and variability. Despite the negative effects brought by climate variability, smallholder farmers are still able to derive livelihoods. An understanding of factors that influence farmers’ responses and adaptation to climate variability can improve decision making for governments and development partners. This study investigated farmers’ perceptions and adaptation strategies to climate change and how these influence adaptation policies at local level. A survey was conducted with 100 households randomly selected from Chiredzi district. Data collected was used to derive farmer perceptions to climate change as well as the influence of their perceptions and subsequent adaptation methods to ensuing local agricultural adaptation measures and policies. The results indicated that smallholder farmers perceived general reduction in long-term annual rainfall and rising local average temperatures. Adverse trends in rainfall and average temperature perceived by farmers were consistent with empirical data. These perceptions and other socio-economic factors helped to shape smallholder farmer agricultural adaptation strategies. Policy implications are that the government and development partners should seek ways to assist autonomous adaptations by farmers through investments in planned adaptation initiatives.

  17. An adapted yield criterion for the evolution of subsequent yield surfaces

    Science.gov (United States)

    Küsters, N.; Brosius, A.

    2017-09-01

    In numerical analysis of sheet metal forming processes, the anisotropic material behaviour is often modelled with isotropic work hardening and an average Lankford coefficient. In contrast, experimental observations show an evolution of the Lankford coefficients, which can be associated with a yield surface change due to kinematic and distortional hardening. Commonly, extensive efforts are carried out to describe these phenomena. In this paper an isotropic material model based on the Yld2000-2d criterion is adapted with an evolving yield exponent in order to change the yield surface shape. The yield exponent is linked to the accumulative plastic strain. This change has the effect of a rotating yield surface normal. As the normal is directly related to the Lankford coefficient, the change can be used to model the evolution of the Lankford coefficient during yielding. The paper will focus on the numerical implementation of the adapted material model for the FE-code LS-Dyna, mpi-version R7.1.2-d. A recently introduced identification scheme [1] is used to obtain the parameters for the evolving yield surface and will be briefly described for the proposed model. The suitability for numerical analysis will be discussed for deep drawing processes in general. Efforts for material characterization and modelling will be compared to other common yield surface descriptions. Besides experimental efforts and achieved accuracy, the potential of flexibility in material models and the risk of ambiguity during identification are of major interest in this paper.

  18. An adaptive left–right eigenvector evolution algorithm for vibration isolation control

    International Nuclear Information System (INIS)

    Wu, T Y

    2009-01-01

    The purpose of this research is to investigate the feasibility of utilizing an adaptive left and right eigenvector evolution (ALREE) algorithm for active vibration isolation. As depicted in the previous paper presented by Wu and Wang (2008 Smart Mater. Struct. 17 015048), the structural vibration behavior depends on both the disturbance rejection capability and mode shape distributions, which correspond to the left and right eigenvector distributions of the system, respectively. In this paper, a novel adaptive evolution algorithm is developed for finding the optimal combination of left–right eigenvectors of the vibration isolator, which is an improvement over the simultaneous left–right eigenvector assignment (SLREA) method proposed by Wu and Wang (2008 Smart Mater. Struct. 17 015048). The isolation performance index used in the proposed algorithm is defined by combining the orthogonality index of left eigenvectors and the modal energy ratio index of right eigenvectors. Through the proposed ALREE algorithm, both the left and right eigenvectors evolve such that the isolation performance index decreases, and therefore one can find the optimal combination of left–right eigenvectors of the closed-loop system for vibration isolation purposes. The optimal combination of left–right eigenvectors is then synthesized to determine the feedback gain matrix of the closed-loop system. The result of the active isolation control shows that the proposed method can be utilized to improve the vibration isolation performance compared with the previous approaches

  19. Adaptation to an extraordinary environment by evolution of phenotypic plasticity and genetic assimilation.

    Science.gov (United States)

    Lande, Russell

    2009-07-01

    Adaptation to a sudden extreme change in environment, beyond the usual range of background environmental fluctuations, is analysed using a quantitative genetic model of phenotypic plasticity. Generations are discrete, with time lag tau between a critical period for environmental influence on individual development and natural selection on adult phenotypes. The optimum phenotype, and genotypic norms of reaction, are linear functions of the environment. Reaction norm elevation and slope (plasticity) vary among genotypes. Initially, in the average background environment, the character is canalized with minimum genetic and phenotypic variance, and no correlation between reaction norm elevation and slope. The optimal plasticity is proportional to the predictability of environmental fluctuations over time lag tau. During the first generation in the new environment the mean fitness suddenly drops and the mean phenotype jumps towards the new optimum phenotype by plasticity. Subsequent adaptation occurs in two phases. Rapid evolution of increased plasticity allows the mean phenotype to closely approach the new optimum. The new phenotype then undergoes slow genetic assimilation, with reduction in plasticity compensated by genetic evolution of reaction norm elevation in the original environment.

  20. GNBP domain of Anopheles darlingi: are polymorphic inversions and gene variation related to adaptive evolution?

    Science.gov (United States)

    Bridi, L C; Rafael, M S

    2016-02-01

    Anopheles darlingi is the main malaria vector in humans in South America. In the Amazon basin, it lives along the banks of rivers and lakes, which responds to the annual hydrological cycle (dry season and rainy season). In these breeding sites, the larvae of this mosquito feed on decomposing organic and microorganisms, which can be pathogenic and trigger the activation of innate immune system pathways, such as proteins Gram-negative binding protein (GNBP). Such environmental changes affect the occurrence of polymorphic inversions especially at the heterozygote frequency, which confer adaptative advantage compared to homozygous inversions. We mapped the GNBP probe to the An. darlingi 2Rd inversion by fluorescent in situ hybridization (FISH), which was a good indicator of the GNBP immune response related to the chromosomal polymorphic inversions and adaptative evolution. To better understand the evolutionary relations and time of divergence of the GNBP of An. darlingi, we compared it with nine other mosquito GNBPs. The results of the phylogenetic analysis of the GNBP sequence between the species of mosquitoes demonstrated three clades. Clade I and II included the GNBPB5 sequence, and clade III the sequence of GNBPB1. Most of these sequences of GNBP analyzed were homologous with that of subfamily B, including that of An. gambiae (87 %), therefore suggesting that GNBP of An. darling belongs to subfamily B. This work helps us understand the role of inversion polymorphism in evolution of An. darlingi.

  1. Adaptation to climate change. Strategy and policy; Aanpassing aan klimaatverandering. Strategie en beleid

    Energy Technology Data Exchange (ETDEWEB)

    NONE

    2012-11-15

    The Court of Audit investigated the Dutch 'climate adaptation policy', or the measures taken to adapt to the impacts of climate change Netherlands and thus reduce its vulnerability [Dutch] De Algemene Rekenkamer heeft onderzoek gedaan naar het Nederlandse 'klimaatadaptatiebeleid', oftewel naar de maatregelen die worden getroffen om Nederland aan te passen aan de gevolgen van de klimaatverandering en zodoende minder kwetsbaar te maken.

  2. Climate Change Impacts and Adaptation Strategies in Northwest China

    Institute of Scientific and Technical Information of China (English)

    ZHAO Hong-Yan; LIU Cai-Hong; LI Yan-Chun; FANG Jian-Gang; LI Lin; LI Hong-Mei; ZHENG Guang-Fen; DENG Zhen-Yong; DONG An-Xiang; GUO Jun-Qin; ZHANG Cun-Jie; SUN Lan-Dong; ZHANG Xu-Dong; LIN Jing-Jing; WANG You-Heng; FANG Feng; MA Peng-Li

    2014-01-01

    Climate change resulted in changes in crop growth duration and planting structure, northward movement of planting region, and more severe plant diseases and insect pests in Northwest China. It caused earlier seeding for spring crop, later seeding for autumn crop, accelerated crop growth, and reduced mortality for winter crop. To adapt to climate change, measures such as optimization of agricultural arrangement, adjustment of planting structure, expansion of thermophilic crops, and development of water-saving agriculture have been taken. Damaging consequences of imbalance between grassland and livestock were enhanced. The deterioration trend of grassland was intensified; both grass quantity and quality declined. With overgrazing, proportions of inferior grass, weeds and poisonous weeds increased in plateau pastoral areas. Returning farmland to grazing, returning grazing to grassland, fence enclosure and artificial grassland construction have been implemented to restore the grassland vegetation, to increase the grassland coverage, to reasonably control the livestock carrying capacity, to prevent overgrazing, to keep balance between grassland and livestock, and to develop the ecological animal husbandry. In Northwest China, because the amount of regional water resources had an overall decreasing trend, there was a continuous expansion in the regional land desertification, and soil erosion was very serious. A series of measures, such as development of artificial precipitation (snow), water resources control, regional water diversion, water storage project and so on, were used effectively to respond to water deficit. It had played a certain role in controlling soil erosion by natural forest protection and returning farmland to forest and grassland. In the early 21st century, noticeable achievements had been made in prevention and control of desertification in Northwest China. The regional ecological environment has been improved obviously, and the desertification trend

  3. Complex adaptive strategy to produce capacity-driven financial improvement.

    Science.gov (United States)

    Capuano, Terry; MacKenzie, Richard; Pintar, Kristi; Halkins, Deborah; Nester, Brian

    2009-01-01

    Managing capacity in hospitals and emergency departments (EDs) is a global problem. This article demonstrates an efficiency model applied to an acute care hospital facing a budget shortfall as a result of capacity constraints that negatively affected admissions and increased ED diversions. Operating on the hypothesis that reducing inpatient length of stay would allow patients access through all service points and would return the admissions growth rate to budget, a turnaround team was quickly assembled and charged by the chief executive officer to fix the primary cause of financial underperformance--the creeping length of stay--within 60 days. This case study is generalizable to all organizations, regardless of size. Deploying an efficiency model based on the complex adaptive systems approach of "swarmware," the hospital's rapid turnaround efforts produced the results necessary to achieve two established goals: (1) length of stay was decreased to 0.1 days below budget in the 60-day time frame, and (2) all admissions and potential admissions were accepted (saying "yes" to patients) through key points of access in the hospital. Transfer Center denials were reduced to 0 in 19 days, and monthly ED diversions decreased from 110 hours to 20 hours in 60 days. By using a swarmware approach, the hospital created additional bed capacity, allowing for community demand to be accommodated, budgeted admissions target to be exceeded, and market share to be stabilized. This article describes this project's processes and outcomes and the lessons learned and applied, which will assist healthcare leaders who are facing capacity issues in their own organization.

  4. The evolution of intellectual property strategy in innovation ecosystems

    DEFF Research Database (Denmark)

    Holgersson, Marcus; Granstrand, Ove; Bogers, Marcel

    2018-01-01

    In this article, we attempt to extend and nuance the debate on intellectual property (IP) strategy, appropriation, and open innovation in dynamic and systemic innovation contexts. We present the case of four generations of mobile telecommunications systems (covering the period 1980-2015), and des......In this article, we attempt to extend and nuance the debate on intellectual property (IP) strategy, appropriation, and open innovation in dynamic and systemic innovation contexts. We present the case of four generations of mobile telecommunications systems (covering the period 1980...... and technologies to benefit from openness and appropriation of innovation. Our analysis shows that the discussion of competitiveness and appropriability needs to be expanded from the focal appropriability regime and complementary assets to the larger context of the innovation ecosystem and its cooperative...... and competitive actor relations, with dispersed complementary and substitute assets and technologies. Consequently, the shaping of complementary and substitute appropriability regimes is central when strategizing in dynamic and systemic innovation contexts. This holds important implications for the management...

  5. How will the EU climate adaptation strategy affect EU agricultural policies?

    DEFF Research Database (Denmark)

    Nielsen, Helle Ørsted; Karali, Eleni; Castellari, Sergio

    A key objective in the EU Strategy on adaptation to climate change (COM (2013) 216 final) is to ensure mainstreaming, i.e. integration, of adaptation measures into European sectoral policies. The Common Agricultural Policy (CAP) is one such sectoral policy which is prioritised in the strategy...... as an area to be climate proofed. The CAP is under revision and will be reformed for the 2014-2020 period with the explicit objectives of strengthening the competitiveness and the sustainability of agriculture (EC). Climate change adaptation objectives are included in the proposal for a greening...... of the single payment scheme (2011/0280 (COD), and the proposal for the Rural Development Fund also specifically sets out climate change adaptation as a cross-cutting objective to which rural development funding must contribute 2011/0282 (COD). This paper therefore examines the most important challenges...

  6. Role of environmental variability in the evolution of life history strategies.

    Science.gov (United States)

    Hastings, A; Caswell, H

    1979-09-01

    We reexamine the role of environmental variability in the evolution of life history strategies. We show that normally distributed deviations in the quality of the environment should lead to normally distributed deviations in the logarithm of year-to-year survival probabilities, which leads to interesting consequences for the evolution of annual and perennial strategies and reproductive effort. We also examine the effects of using differing criteria to determine the outcome of selection. Some predictions of previous theory are reversed, allowing distinctions between r and K theory and a theory based on variability. However, these distinctions require information about both the environment and the selection process not required by current theory.

  7. Climate change effects and adaptation strategies in the wine sector: a quantitative literature review

    Directory of Open Access Journals (Sweden)

    Sandro Sacchelli

    2016-12-01

    Full Text Available This paper presents a quantitative literature review focusing on how scientific research analysed climate change impact on wine chain as well as potential adaptation strategies. The work is based on content analysis and text mining and takes into account researches from 1990 to 2015. A particular emphasis was given to the evaluation of suggested or implemented adaptation strategies at both global and national levels. Data were analysed using cluster analysis, multidimensional scaling and specificity evaluation. Results show that the study of climate change impacts on the wine sector is a recently emerging research topic. Adaptation strategies have not yet been explored thoroughly in the literature, and in-depth uncertainty quantification is also needed. Finally, additional research gaps and potential future issues are suggested.

  8. Recruitment of hard-to-reach population subgroups via adaptations of the snowball sampling strategy.

    Science.gov (United States)

    Sadler, Georgia Robins; Lee, Hau-Chen; Lim, Rod Seung-Hwan; Fullerton, Judith

    2010-09-01

    Nurse researchers and educators often engage in outreach to narrowly defined populations. This article offers examples of how variations on the snowball sampling recruitment strategy can be applied in the creation of culturally appropriate, community-based information dissemination efforts related to recruitment to health education programs and research studies. Examples from the primary author's program of research are provided to demonstrate how adaptations of snowball sampling can be used effectively in the recruitment of members of traditionally underserved or vulnerable populations. The adaptation of snowball sampling techniques, as described in this article, helped the authors to gain access to each of the more-vulnerable population groups of interest. The use of culturally sensitive recruitment strategies is both appropriate and effective in enlisting the involvement of members of vulnerable populations. Adaptations of snowball sampling strategies should be considered when recruiting participants for education programs or for research studies when the recruitment of a population-based sample is not essential.

  9. Evolving local climate adaptation strategies: incorporating influences of socio–economic stress

    OpenAIRE

    Hjerpe, Mattias; Glaas, Erik

    2012-01-01

    Socio-economic and climatic stresses affect local communities’ vulnerability toflooding. Better incorporation of socio-economic stress in local vulnerability assessments isimportant when planning for climate adaptation. This is rarely done due to insufficientunderstanding of their interaction, in both theory and practice. The omission leads to criticalweaknesses in local adaptation strategies. This study analyses how socio-economic stressinteract with climatic stress and shape local vulnerabi...

  10. Synergies, Conflicts, and Trade-offs of C40 Cities Adaptation Strategies

    DEFF Research Database (Denmark)

    Driscoll, Patrick Arthur; De Rosa, Michele; Lehmann, Martin

    2013-01-01

    There is a growing body of literature in the field of urban climate change adaptation planning that indicate a need to address climate change planning measures from a more holistic sustainable development perspective. This paper presents the findings from a recently completed study that indicates...... there remain significant unresolved tensions between the development pathways and the climate change adaptation strategies of the 58 cities within the C40 Cities Climate Leadership Group....

  11. Developmental prosopagnosia and adaptative compensatory strategies: Case study

    Directory of Open Access Journals (Sweden)

    Anair Rodrigues

    Full Text Available Abstract Prosopagnosia is a type of visual agnosia with inability to identify faces, usually secondary to brain lesion in associative cortex areas, but there is also a congenital form known as developmental prosopagnosia. Objectives: To describe a case of developmental prosopagnosia that illustrates the specificity of the pathways for perception of faces in the visual system. Also, we will describe possible mechanisms of recognition used by this patient. Methods: R.S., a 50 year-old woman, was referred for neuropsychological assessment due to difficulties in perception of familiar faces since childhood, unexplained by any loss of visual acuity. Results: The exam showed good performance for comprehension, reasoning, concept formation, constructional abilities, criticism, judgment, mental control, memory and visual perception for other kinds of stimuli. No difficulties were seen regarding identification of ethnicity, age and types of animals. The patient was able to match celebrities' faces in different positions, but could not identify the matching pictures for unknown people. Conclusions: These findings indicate the patient had developed strategies, throughout life, to recognize familiar faces (relatives, celebrities from memorized fragments, but still had difficulties in identifying non-familiar faces holistically.

  12. The king cobra genome reveals dynamic gene evolution and adaptation in the snake venom system.

    Science.gov (United States)

    Vonk, Freek J; Casewell, Nicholas R; Henkel, Christiaan V; Heimberg, Alysha M; Jansen, Hans J; McCleary, Ryan J R; Kerkkamp, Harald M E; Vos, Rutger A; Guerreiro, Isabel; Calvete, Juan J; Wüster, Wolfgang; Woods, Anthony E; Logan, Jessica M; Harrison, Robert A; Castoe, Todd A; de Koning, A P Jason; Pollock, David D; Yandell, Mark; Calderon, Diego; Renjifo, Camila; Currier, Rachel B; Salgado, David; Pla, Davinia; Sanz, Libia; Hyder, Asad S; Ribeiro, José M C; Arntzen, Jan W; van den Thillart, Guido E E J M; Boetzer, Marten; Pirovano, Walter; Dirks, Ron P; Spaink, Herman P; Duboule, Denis; McGlinn, Edwina; Kini, R Manjunatha; Richardson, Michael K

    2013-12-17

    Snakes are limbless predators, and many species use venom to help overpower relatively large, agile prey. Snake venoms are complex protein mixtures encoded by several multilocus gene families that function synergistically to cause incapacitation. To examine venom evolution, we sequenced and interrogated the genome of a venomous snake, the king cobra (Ophiophagus hannah), and compared it, together with our unique transcriptome, microRNA, and proteome datasets from this species, with data from other vertebrates. In contrast to the platypus, the only other venomous vertebrate with a sequenced genome, we find that snake toxin genes evolve through several distinct co-option mechanisms and exhibit surprisingly variable levels of gene duplication and directional selection that correlate with their functional importance in prey capture. The enigmatic accessory venom gland shows a very different pattern of toxin gene expression from the main venom gland and seems to have recruited toxin-like lectin genes repeatedly for new nontoxic functions. In addition, tissue-specific microRNA analyses suggested the co-option of core genetic regulatory components of the venom secretory system from a pancreatic origin. Although the king cobra is limbless, we recovered coding sequences for all Hox genes involved in amniote limb development, with the exception of Hoxd12. Our results provide a unique view of the origin and evolution of snake venom and reveal multiple genome-level adaptive responses to natural selection in this complex biological weapon system. More generally, they provide insight into mechanisms of protein evolution under strong selection.

  13. The king cobra genome reveals dynamic gene evolution and adaptation in the snake venom system

    Science.gov (United States)

    Vonk, Freek J.; Casewell, Nicholas R.; Henkel, Christiaan V.; Heimberg, Alysha M.; Jansen, Hans J.; McCleary, Ryan J. R.; Kerkkamp, Harald M. E.; Vos, Rutger A.; Guerreiro, Isabel; Calvete, Juan J.; Wüster, Wolfgang; Woods, Anthony E.; Logan, Jessica M.; Harrison, Robert A.; Castoe, Todd A.; de Koning, A. P. Jason; Pollock, David D.; Yandell, Mark; Calderon, Diego; Renjifo, Camila; Currier, Rachel B.; Salgado, David; Pla, Davinia; Sanz, Libia; Hyder, Asad S.; Ribeiro, José M. C.; Arntzen, Jan W.; van den Thillart, Guido E. E. J. M.; Boetzer, Marten; Pirovano, Walter; Dirks, Ron P.; Spaink, Herman P.; Duboule, Denis; McGlinn, Edwina; Kini, R. Manjunatha; Richardson, Michael K.

    2013-01-01

    Snakes are limbless predators, and many species use venom to help overpower relatively large, agile prey. Snake venoms are complex protein mixtures encoded by several multilocus gene families that function synergistically to cause incapacitation. To examine venom evolution, we sequenced and interrogated the genome of a venomous snake, the king cobra (Ophiophagus hannah), and compared it, together with our unique transcriptome, microRNA, and proteome datasets from this species, with data from other vertebrates. In contrast to the platypus, the only other venomous vertebrate with a sequenced genome, we find that snake toxin genes evolve through several distinct co-option mechanisms and exhibit surprisingly variable levels of gene duplication and directional selection that correlate with their functional importance in prey capture. The enigmatic accessory venom gland shows a very different pattern of toxin gene expression from the main venom gland and seems to have recruited toxin-like lectin genes repeatedly for new nontoxic functions. In addition, tissue-specific microRNA analyses suggested the co-option of core genetic regulatory components of the venom secretory system from a pancreatic origin. Although the king cobra is limbless, we recovered coding sequences for all Hox genes involved in amniote limb development, with the exception of Hoxd12. Our results provide a unique view of the origin and evolution of snake venom and reveal multiple genome-level adaptive responses to natural selection in this complex biological weapon system. More generally, they provide insight into mechanisms of protein evolution under strong selection. PMID:24297900

  14. A Bayesian Network Based Adaptability Design of Product Structures for Function Evolution

    Directory of Open Access Journals (Sweden)

    Shaobo Li

    2018-03-01

    Full Text Available Structure adaptability design is critical for function evolution in product families, in which many structural and functional design factors are intertwined together with manufacturing cost, customer satisfaction, and final market sales. How to achieve a delicate balance among all of these factors to maximize the market performance of the product is too complicated to address based on traditional domain experts’ knowledge or some ad hoc heuristics. Here, we propose a quantitative product evolution design model that is based on Bayesian networks to model the dynamic relationship between customer needs and product structure design. In our model, all of the structural or functional features along with customer satisfaction, manufacturing cost, sale price, market sales, and indirect factors are modeled as random variables denoted as nodes in the Bayesian networks. The structure of the Bayesian model is then determined based on the historical data, which captures the dynamic sophisticated relationship of customer demands of a product, structural design, and market performance. Application of our approach to an electric toothbrush product family evolution design problem shows that our model allows for designers to interrogate with the model and obtain theoretical and decision support for dynamic product feature design process.

  15. The evolution model of Uppsala in light of the complex adaptive systems approach

    Directory of Open Access Journals (Sweden)

    Rennaly Alves da Silva

    2013-11-01

    Full Text Available The behavioral approach to the internationalization of companies explains that the movements toward external markets occur in accordance with the increasing commitment of resources to mitigate the effects of uncertainty and reduce the perception of risk. Evidence indicates that the theories and practices developed in the domestic market may not be able to explain the reality of companies that operate in international markets. Thus, the Paradigm of Complexity presents itself as a comprehensive alternative to realize the relationships within organizations and markets. Accordingly, the aim of this theoretical paper is to analyze the evolution of the Uppsala Model between years 1975 and 2010 with the understanding of the companies in the process of internationalization as Complex Adaptive Systems, in accordance with the Model Kelly and Allison (1998. Four propositions are presented that show the links between the approaches. The most surprising is the perception that the conceptual evolution of the Uppsala Model seems to accompany the evolution of complexity levels, presented in Model Kelly and Allison.

  16. Adaptive Evolution of the Myo6 Gene in Old World Fruit Bats (Family: Pteropodidae)

    Science.gov (United States)

    Shen, Bin; Han, Xiuqun; Jones, Gareth; Rossiter, Stephen J.; Zhang, Shuyi

    2013-01-01

    Myosin VI (encoded by the Myo6 gene) is highly expressed in the inner and outer hair cells of the ear, retina, and polarized epithelial cells such as kidney proximal tubule cells and intestinal enterocytes. The Myo6 gene is thought to be involved in a wide range of physiological functions such as hearing, vision, and clathrin-mediated endocytosis. Bats (Chiroptera) represent one of the most fascinating mammal groups for molecular evolutionary studies of the Myo6 gene. A diversity of specialized adaptations occur among different bat lineages, such as echolocation and associated high-frequency hearing in laryngeal echolocating bats, large eyes and a strong dependence on vision in Old World fruit bats (Pteropodidae), and specialized high-carbohydrate but low-nitrogen diets in both Old World and New World fruit bats (Phyllostomidae). To investigate what role(s) the Myo6 gene might fulfill in bats, we sequenced the coding region of the Myo6 gene in 15 bat species and used molecular evolutionary analyses to detect evidence of positive selection in different bat lineages. We also conducted real-time PCR assays to explore the expression levels of Myo6 in a range of tissues from three representative bat species. Molecular evolutionary analyses revealed that the Myo6 gene, which was widely considered as a hearing gene, has undergone adaptive evolution in the Old World fruit bats which lack laryngeal echolocation and associated high-frequency hearing. Real-time PCR showed the highest expression level of the Myo6 gene in the kidney among ten tissues examined in three bat species, indicating an important role for this gene in kidney function. We suggest that Myo6 has undergone adaptive evolution in Old World fruit bats in relation to receptor-mediated endocytosis for the preservation of protein and essential nutrients. PMID:23620821

  17. Rapid and Parallel Adaptive Evolution of the Visual System of Neotropical Midas Cichlid Fishes.

    Science.gov (United States)

    Torres-Dowdall, Julián; Pierotti, Michele E R; Härer, Andreas; Karagic, Nidal; Woltering, Joost M; Henning, Frederico; Elmer, Kathryn R; Meyer, Axel

    2017-10-01

    Midas cichlid fish are a Central American species flock containing 13 described species that has been dated to only a few thousand years old, a historical timescale infrequently associated with speciation. Their radiation involved the colonization of several clear water crater lakes from two turbid great lakes. Therefore, Midas cichlids have been subjected to widely varying photic conditions during their radiation. Being a primary signal relay for information from the environment to the organism, the visual system is under continuing selective pressure and a prime organ system for accumulating adaptive changes during speciation, particularly in the case of dramatic shifts in photic conditions. Here, we characterize the full visual system of Midas cichlids at organismal and genetic levels, to determine what types of adaptive changes evolved within the short time span of their radiation. We show that Midas cichlids have a diverse visual system with unexpectedly high intra- and interspecific variation in color vision sensitivity and lens transmittance. Midas cichlid populations in the clear crater lakes have convergently evolved visual sensitivities shifted toward shorter wavelengths compared with the ancestral populations from the turbid great lakes. This divergence in sensitivity is driven by changes in chromophore usage, differential opsin expression, opsin coexpression, and to a lesser degree by opsin coding sequence variation. The visual system of Midas cichlids has the evolutionary capacity to rapidly integrate multiple adaptations to changing light environments. Our data may indicate that, in early stages of divergence, changes in opsin regulation could precede changes in opsin coding sequence evolution. © The Author 2017. Published by Oxford University Press on behalf of the Society for Molecular Biology and Evolution. All rights reserved. For permissions, please e-mail: journals.permissions@oup.com.

  18. Adapting to climate change in forest based land use systems: A guide to strategy

    Energy Technology Data Exchange (ETDEWEB)

    Secrett, C M

    1997-12-31

    The prospect of climate change and sea level rise as a result of greenhouse gas emissions presents a serious challenge to decision-makers concerned with ensuring sustainable development. This report provides a guide to means of reducing the potential impact of the global warming problem on the forest sector whilst ensuring that more immediate development priorities are met. The most effective response strategy will be one that simultaneously brings both immediate development and longer-term adaptive benefits. This report outlines ways of constructing an adaptive response strategy that can help achieve these ends. The approach is referred to as sustainable adaptation. A prototype methodological framework of the sustainable adaptation approach has been provided with the summary. The first priority of sustainable adaption is to base climate change responses on actions that meet basic ecological and social needs now and in the future. Solutions should necessarily include relieving current development pressures in the tropical forest sector. The key is to couple adaptive responses to climate change with sustainable development solutions to present-day forest use problems. Implementing adaptive land-use policies and management practices which are likely to minimise the adverse impacts of anticipated climate change should meet current sustainable management goals. Implementing sustainable land-use and forestry management practices should meet adaptation goals. This report presents a discussion of the fundamental issues underlying the development of a sustainable adaptation strategy and a prototype methodological framework. The findings are based on case studies conducted in Central America (Costa Rica and Nicaragua); SADCC countries in Africa (Zimbabwe, Botswana, Tanzania); and Asia (Vietnam). 450 refs

  19. Adapting to climate change in forest based land use systems: A guide to strategy

    Energy Technology Data Exchange (ETDEWEB)

    Secrett, C.M.

    1996-12-31

    The prospect of climate change and sea level rise as a result of greenhouse gas emissions presents a serious challenge to decision-makers concerned with ensuring sustainable development. This report provides a guide to means of reducing the potential impact of the global warming problem on the forest sector whilst ensuring that more immediate development priorities are met. The most effective response strategy will be one that simultaneously brings both immediate development and longer-term adaptive benefits. This report outlines ways of constructing an adaptive response strategy that can help achieve these ends. The approach is referred to as sustainable adaptation. A prototype methodological framework of the sustainable adaptation approach has been provided with the summary. The first priority of sustainable adaption is to base climate change responses on actions that meet basic ecological and social needs now and in the future. Solutions should necessarily include relieving current development pressures in the tropical forest sector. The key is to couple adaptive responses to climate change with sustainable development solutions to present-day forest use problems. Implementing adaptive land-use policies and management practices which are likely to minimise the adverse impacts of anticipated climate change should meet current sustainable management goals. Implementing sustainable land-use and forestry management practices should meet adaptation goals. This report presents a discussion of the fundamental issues underlying the development of a sustainable adaptation strategy and a prototype methodological framework. The findings are based on case studies conducted in Central America (Costa Rica and Nicaragua); SADCC countries in Africa (Zimbabwe, Botswana, Tanzania); and Asia (Vietnam). 450 refs

  20. Climate Change Adaptation Strategies and Constraints in Northern Ghana: Evidence of Farmers in Sissala West District

    Directory of Open Access Journals (Sweden)

    Clifford James Fagariba

    2018-05-01

    Full Text Available Research findings indicate that most African countries are vulnerable to climate change as a result of challenges such as poverty, weather extremes, and insufficient governmental agricultural support. For this reason, the researchers used the Sissala West District as a case study to determine factors influencing farmers’ adaptation to climate change and strategies used to avert climate change impact. A total of 330 small-scale farmers were sampled for survey and 150 key informants were used in focus group discussions. Utilizing the logistic regression model, the study indicated irregular rainfall, high temperature, weather information, and high evaporation as the factors that highly influenced farmers’ ability to adapt to climate change. A Weighted Average Index used to measure weather extremes revealed that drought and temperature had the highest level of occurrence. Furthermore, climate change adaptation strategies assessed in the study showed that agroforestry practices, drought-resistant crops, and mulching were the most preferred methods. The study concluded that farmers’ ability to adapt to climate change can be improved if the Environmental Protection Agency and the Ministry of Food and Agriculture intensify climate adaptation campaigns, increase access to weather information, and train farmers on adaptable strategies including, but not limited to, alternative sources of livelihood.

  1. Multilevel Optimization Framework for Hierarchical Stiffened Shells Accelerated by Adaptive Equivalent Strategy

    Science.gov (United States)

    Wang, Bo; Tian, Kuo; Zhao, Haixin; Hao, Peng; Zhu, Tianyu; Zhang, Ke; Ma, Yunlong

    2017-06-01

    In order to improve the post-buckling optimization efficiency of hierarchical stiffened shells, a multilevel optimization framework accelerated by adaptive equivalent strategy is presented in this paper. Firstly, the Numerical-based Smeared Stiffener Method (NSSM) for hierarchical stiffened shells is derived by means of the numerical implementation of asymptotic homogenization (NIAH) method. Based on the NSSM, a reasonable adaptive equivalent strategy for hierarchical stiffened shells is developed from the concept of hierarchy reduction. Its core idea is to self-adaptively decide which hierarchy of the structure should be equivalent according to the critical buckling mode rapidly predicted by NSSM. Compared with the detailed model, the high prediction accuracy and efficiency of the proposed model is highlighted. On the basis of this adaptive equivalent model, a multilevel optimization framework is then established by decomposing the complex entire optimization process into major-stiffener-level and minor-stiffener-level sub-optimizations, during which Fixed Point Iteration (FPI) is employed to accelerate convergence. Finally, the illustrative examples of the multilevel framework is carried out to demonstrate its efficiency and effectiveness to search for the global optimum result by contrast with the single-level optimization method. Remarkably, the high efficiency and flexibility of the adaptive equivalent strategy is indicated by compared with the single equivalent strategy.

  2. The role of uncertainty in climate change adaptation strategies — A Danish water management example

    DEFF Research Database (Denmark)

    Refsgaard, J.C.; Arnbjerg-Nielsen, Karsten; Drews, Martin

    2013-01-01

    We propose a generic framework to characterize climate change adaptation uncertainty according to three dimensions: level, source and nature. Our framework is different, and in this respect more comprehensive, than the present UN Intergovernmental Panel on Climate Change (IPCC) approach and could...... are epistemic (reducible) by nature but uncertainties on adaptation measures are complex, with ambiguity often being added to impact uncertainties. Strategies to deal with uncertainty in climate change adaptation should reflect the nature of the uncertainty sources and how they interact with risk level...

  3. An adaptation strategy of sandland peasants in Yogyakarta toward climate change

    Science.gov (United States)

    Rusdiyana, E.; Suminah

    2018-03-01

    This study aims to explore and describe the adaptation strategies of sandland peasants toward climate change. Qualitative research method was employed and the data were collected through observation. In addition, the recording of the data, interview and the validity of data were determined by triangulation of sources. The results of the research showed that the adaptation strategies of sandland peasants toward climate change were; (1) the adjustment of crop varieties, (2) the utilization of productive crops as wind breaking, and (3) the irrigation system using “sumur panthek”.

  4. Farmers´ perceptions of climate change and agricultural adaptation strategies in rural Sahel

    DEFF Research Database (Denmark)

    Mertz, Ole; Mbow, Cheikh; Reenberg, Anette

    2009-01-01

    Farmers in the Sahel have always been facing climatic variability at intra- and inter-annual and decadal time scales. While coping and adaptation strategies have traditionally included crop diversification, mobility, livelihood diversification, and migration, singling out climate as a direct driver...... of changes is not so simple. Using focus group interviews and a household survey, this study analyzes the perceptions of climate change and the strategies for coping and adaptation by sedentary farmers in the savanna zone of central Senegal. Households are aware of climate variability and identify wind...

  5. Evolution of increased adult longevity in Drosophila melanogaster populations selected for adaptation to larval crowding.

    Science.gov (United States)

    Shenoi, V N; Ali, S Z; Prasad, N G

    2016-02-01

    In holometabolous animals such as Drosophila melanogaster, larval crowding can affect a wide range of larval and adult traits. Adults emerging from high larval density cultures have smaller body size and increased mean life span compared to flies emerging from low larval density cultures. Therefore, adaptation to larval crowding could potentially affect adult longevity as a correlated response. We addressed this issue by studying a set of large, outbred populations of D. melanogaster, experimentally evolved for adaptation to larval crowding for 83 generations. We assayed longevity of adult flies from both selected (MCUs) and control populations (MBs) after growing them at different larval densities. We found that MCUs have evolved increased mean longevity compared to MBs at all larval densities. The interaction between selection regime and larval density was not significant, indicating that the density dependence of mean longevity had not evolved in the MCU populations. The increase in longevity in MCUs can be partially attributed to their lower rates of ageing. It is also noteworthy that reaction norm of dry body weight, a trait probably under direct selection in our populations, has indeed evolved in MCU populations. To the best of our knowledge, this is the first report of the evolution of adult longevity as a correlated response of adaptation to larval crowding. © 2015 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2015 European Society For Evolutionary Biology.

  6. Multiagents-based wide area protection with best-effort adaptive strategy

    Energy Technology Data Exchange (ETDEWEB)

    Zhu, Yongli; Wang, Dewen [North China Electric Power University, Baoding (China); Song, Shaoqun [Fuzhou Electric Power Industry Bureau, Fujian Province (China)

    2009-02-15

    Abstract - Multi-trips of circuit breakers often occur within a short period in a severe blackout, and the tripping usually relates to relays' mal-operations. In fact, when two ore more electric primary devices are isolated by circuit breakers, the settings of most relays to protect their power system are getting infeasible and uncoordinated. Adaptive settings are needed to prevent them from wrong operation. This paper presents an adaptive protection scheme based on wide area information with best-effort protection strategy, and the outline of multiagents and WAN Based Adaptive Protection System (MAWAPS). In the scheme, the best-effort adaptive strategy is used to guarantee the adaptive settings to operate safely and effectively in most situations. The IP/SDH-based wide area network (WAN) is used to realize real-time wide area information exchange in the proposed protection scheme. Adaptive setting algorithms for the second stage zero-sequence current and phase overcurrent relays are proposed, which can provide larger line coverage than traditional relays. Moreover, multiagent techniques and IEC 61850 are employed to realize the fast communication between different agents, and MMS plays a prominent role in real-time remote communication. A simulating system has been developed according to the above ideas and approaches, and the experimental results show that the proposed adaptive protection scheme is feasible from the view of protective performance including the executing time. (author)

  7. Paradoxical cardiovascular effects of implementing adaptive emotion regulation strategies in generalized anxiety disorder.

    Science.gov (United States)

    Aldao, Amelia; Mennin, Douglas S

    2012-02-01

    Recent models of generalized anxiety disorder (GAD) have expanded on Borkovec's avoidance theory by delineating emotion regulation deficits associated with the excessive worry characteristic of this disorder (see Behar, DiMarco, Hekler, Mohlman, & Staples, 2009). However, it has been difficult to determine whether emotion regulation is simply a useful heuristic for the avoidant properties of worry or an important extension to conceptualizations of GAD. Some of this difficulty may arise from a focus on purported maladaptive regulation strategies, which may be confounded with symptomatic distress components of the disorder (such as worry). We examined the implementation of adaptive regulation strategies by participants with and without a diagnosis of GAD while watching emotion-eliciting film clips. In a between-subjects design, participants were randomly assigned to accept, reappraise, or were not given specific regulation instructions. Implementation of adaptive regulation strategies produced differential effects in the physiological (but not subjective) domain across diagnostic groups. Whereas participants with GAD demonstrated lower cardiac flexibility when implementing adaptive regulation strategies than when not given specific instructions on how to regulate, healthy controls showed the opposite pattern, suggesting they benefited from the use of adaptive regulation strategies. We discuss the implications of these findings for the delineation of emotion regulation deficits in psychopathology. Copyright © 2011 Elsevier Ltd. All rights reserved.

  8. Ecomorphological adaptations in Collembola in relation to feeding strategies and microhabitat

    NARCIS (Netherlands)

    Malcicka, Miriama; Berg, Matty P.; Ellers, Jacintha

    2017-01-01

    Some of the most important functional traits in animals are related to the potentially vast array of feeding strategies and microhabitat use. Correlated evolution of diet and habitat specialization with ecomorphological traits has been described in vertebrates, but such functional trait variation in

  9. Oncolytic Immunotherapy: Conceptual Evolution, Current Strategies, and Future Perspectives

    Directory of Open Access Journals (Sweden)

    Zong Sheng Guo

    2017-05-01

    Full Text Available The concept of oncolytic virus (OV-mediated cancer therapy has been shifted from an operational virotherapy paradigm to an immunotherapy. OVs often induce immunogenic cell death (ICD of cancer cells, and they may interact directly with immune cells as well to prime antitumor immunity. We and others have developed a number of strategies to further stimulate antitumor immunity and to productively modulate the tumor microenvironment (TME for potent and sustained antitumor immune cell activity. First, OVs have been engineered or combined with other ICD inducers to promote more effective T cell cross-priming, and in many cases, the breaking of functional immune tolerance. Second, OVs may be armed to express Th1-stimulatory cytokines/chemokines or costimulators to recruit and sustain the potent antitumor immunity into the TME to focus their therapeutic activity within the sites of disease. Third, combinations of OV with immunomodulatory drugs or antibodies that recondition the TME have proven to be highly promising in early studies. Fourth, combinations of OVs with other immunotherapeutic regimens (such as prime-boost cancer vaccines, CAR T cells; armed with bispecific T-cell engagers have also yielded promising preliminary findings. Finally, OVs have been combined with immune checkpoint blockade, with robust antitumor efficacy being observed in pilot evaluations. Despite some expected hurdles for the rapid translation of OV-based state-of-the-art protocols, we believe that a cohort of these novel approaches will join the repertoire of standard cancer treatment options in the near future.

  10. Genetic evolution, plasticity, and bet-hedging as adaptive responses to temporally autocorrelated fluctuating selection: A quantitative genetic model.

    Science.gov (United States)

    Tufto, Jarle

    2015-08-01

    Adaptive responses to autocorrelated environmental fluctuations through evolution in mean reaction norm elevation and slope and an independent component of the phenotypic variance are analyzed using a quantitative genetic model. Analytic approximations expressing the mutual dependencies between all three response modes are derived and solved for the joint evolutionary outcome. Both genetic evolution in reaction norm elevation and plasticity are favored by slow temporal fluctuations, with plasticity, in the absence of microenvironmental variability, being the dominant evolutionary outcome for reasonable parameter values. For fast fluctuations, tracking of the optimal phenotype through genetic evolution and plasticity is limited. If residual fluctuations in the optimal phenotype are large and stabilizing selection is strong, selection then acts to increase the phenotypic variance (bet-hedging adaptive). Otherwise, canalizing selection occurs. If the phenotypic variance increases with plasticity through the effect of microenvironmental variability, this shifts the joint evolutionary balance away from plasticity in favor of genetic evolution. If microenvironmental deviations experienced by each individual at the time of development and selection are correlated, however, more plasticity evolves. The adaptive significance of evolutionary fluctuations in plasticity and the phenotypic variance, transient evolution, and the validity of the analytic approximations are investigated using simulations. © 2015 The Author(s). Evolution © 2015 The Society for the Study of Evolution.

  11. Coping strategies and resources as predictors of psychosocial adaptation among people with spinal cord injury.

    Science.gov (United States)

    Livneh, Hanoch; Martz, Erin

    2014-08-01

    The onset of a spinal cord injury (SCI) is accompanied by a massive amount of stress, on which professionals in the medical field focus attention and care. The subsequent cascade of psychological stressors related to SCI often receives lesser attention. When individuals experience new forms of stress, they typically respond with attempts to cope, which may or may not be adaptive in reducing their stress levels. The twofold purpose of this study was to investigate whether SCI survivors' use of coping resources (i.e., hope, sense of coherence) and coping strategies (e.g., engagement coping, seeking social support) influences their psychosocial adaptation, and whether their use of coping strategies moderates the effect of coping resources, after controlling for the influence of depression and anxiety, on psychosocial adaptation. This cross-sectional study involved a self-report survey of survivors of SCI. Inclusion criteria included: (a) being 18 years of age or older, (b) having received inpatient rehabilitation services following the SCI, and (c) not having traumatic head injury at the time of the SCI onset. The sample consisted of 95 individuals with SCI who received outpatient rehabilitation services at a center in the midsouthern United States. Results indicated that coping resources and coping strategies were significantly associated with psychosocial adaptation. Furthermore, engagement coping explained a significant portion of the variance in psychosocial adaptation both individually and as an interactive variable with the 2 coping resources of sense of coherence and hope. Findings indicate that both coping resources and strategies (especially engagement coping) are reliably linked to adaptation to SCI. The findings further suggest that engagement coping positively influences psychosocial adaptation even when coping resources are mostly absent. Other implications for the field of rehabilitation are briefly outlined.

  12. Developing Marketing Higher Education Strategies Based on Students’ Satisfaction Evolution

    Directory of Open Access Journals (Sweden)

    Andreea Orîndaru

    2015-09-01

    Full Text Available The educational system worldwide is currently under the spotlight as it shows significant signs of an ongoing crisis in its search for resources, visibility in the crowded market and significance to the ever-changing society. Within this framework, higher education institutions (HEIs are taking significant actions for maintaining students as clients of their educational services. As competition on this market is becoming stronger, HEIs face difficulties in keeping students, leading them to a continuous evaluation of student satisfaction indicators. Beyond HEIs’ managers, researchers in marketing higher education have contributed to the development of a comprehensive literature where still very few have forwarded a longitudinal research model for student satisfaction evaluation despite the need for such approaches. Given this context, the current paper presents a first step towards a longitudinal study as it displays, in a compare and contrast vision, the results of two different quantitative research projects developed in the same student community, with the same objective, but conducted in two different years. Among the most significant results of this research refer to an important decline in students’ satisfaction with a significant increase in the number of students that have a neutral perception. This is highly expected to determine a major impact on university’s overall performance and, therefore, it constitutes a strong argument for determining underlying causes, and especially developing the appropriate marketing strategies to tackle with these issues. Based on this result and other similar research outcomes, strategic and tactic recommendations are granted in the final part of this paper.

  13. Cloud computing task scheduling strategy based on improved differential evolution algorithm

    Science.gov (United States)

    Ge, Junwei; He, Qian; Fang, Yiqiu

    2017-04-01

    In order to optimize the cloud computing task scheduling scheme, an improved differential evolution algorithm for cloud computing task scheduling is proposed. Firstly, the cloud computing task scheduling model, according to the model of the fitness function, and then used improved optimization calculation of the fitness function of the evolutionary algorithm, according to the evolution of generation of dynamic selection strategy through dynamic mutation strategy to ensure the global and local search ability. The performance test experiment was carried out in the CloudSim simulation platform, the experimental results show that the improved differential evolution algorithm can reduce the cloud computing task execution time and user cost saving, good implementation of the optimal scheduling of cloud computing tasks.

  14. Mixed-integer evolution strategies for parameter optimization and their applications to medical image analysis

    NARCIS (Netherlands)

    Li, Rui

    2009-01-01

    The target of this work is to extend the canonical Evolution Strategies (ES) from traditional real-valued parameter optimization domain to mixed-integer parameter optimization domain. This is necessary because there exist numerous practical optimization problems from industry in which the set of

  15. ADAPTIVE CAPACITIES OF FARMERS TO CLIMATE CHANGE ADAPTATION STRATEGIES AND THEIR EFFECTS ON RICE PRODUCTION IN THE NORTHERN REGION OF GHANA

    Directory of Open Access Journals (Sweden)

    Franklin Nantui Mabe

    2012-11-01

    Full Text Available This study estimated the adaptive capacities of farmers to climate change adaptation strategies and their effects on rice production in the Northern Region of Ghana. The adaptive capacities of rice farmers were estimated quantitatively and categorized into high, moderate and low adaptive capacities. Double logarithmic regression model of Cobb-Douglas production function was used to quantity the effects of adaptive capacities of farmers on rice production. On the average, the farmers interviewed are moderately adaptive to climate change. Also, high adaptive farmers obtain nine more bags of 50 kg bag of paddy rice than farmers with low adaptive capacities. Therefore, the more a farmer has the ability to adjust to climate change, the more the number of bags of rice he or she obtains. Rice farmers should be empowered through better extension services in order to attain high adaptive capacity status so as to help them obtain more rice output.

  16. Teaching evolution (and all of biology) more effectively: Strategies for engagement, critical reasoning, and confronting misconceptions.

    Science.gov (United States)

    Nelson, Craig E

    2008-08-01

    The strength of the evidence supporting evolution has increased markedly since the discovery of DNA but, paradoxically, public resistance to accepting evolution seems to have become stronger. A key dilemma is that science faculty have often continued to teach evolution ineffectively, even as the evidence that traditional ways of teaching are inferior has become stronger and stronger. Three pedagogical strategies that together can make a large difference in students' understanding and acceptance of evolution are extensive use of interactive engagement, a focus on critical thinking in science (especially on comparisons and explicit criteria) and using both of these in helping the students actively compare their initial conceptions (and publicly popular misconceptions) with more fully scientific conceptions. The conclusion that students' misconceptions must be dealt with systematically can be difficult for faculty who are teaching evolution since much of the students' resistance is framed in religious terms and one might be reluctant to address religious ideas in class. Applications to teaching evolution are illustrated with examples that address criteria and critical thinking, standard geology versus flood geology, evolutionary developmental biology versus organs of extreme perfection, and the importance of using humans as a central example. It is also helpful to bridge the false dichotomy, seen by many students, between atheistic evolution versus religious creationism. These applications are developed in detail and are intended to be sufficient to allow others to use these approaches in their teaching. Students and other faculty were quite supportive of these approaches as implemented in my classes.

  17. Whole-Genome Scans Provide Evidence of Adaptive Evolution in Malawian Plasmodium falciparum Isolates

    DEFF Research Database (Denmark)

    Ocholla, Harold; Preston, Mark D; Mipando, Mwapatsa

    2014-01-01

    BACKGROUND:  Selection by host immunity and antimalarial drugs has driven extensive adaptive evolution in Plasmodium falciparum and continues to produce ever-changing landscapes of genetic variation. METHODS:  We performed whole-genome sequencing of 69 P. falciparum isolates from Malawi and used......, an area of high malaria transmission. Allele frequency-based tests provided evidence of recent population growth in Malawi and detected potential targets of host immunity and candidate vaccine antigens. Comparison of the sequence variation between isolates from Malawi and those from 5 geographically...... dispersed countries (Kenya, Burkina Faso, Mali, Cambodia, and Thailand) detected population genetic differences between Africa and Asia, within Southeast Asia, and within Africa. Haplotype-based tests of selection to sequence data from all 6 populations identified signals of directional selection at known...

  18. Adaptive Differential Evolution Approach for Constrained Economic Power Dispatch with Prohibited Operating Zones

    Directory of Open Access Journals (Sweden)

    Abdellatif HAMOUDA

    2011-12-01

    Full Text Available Economic power dispatch (EPD is one of the main tools for optimal operation and planning of modern power systems. To solve effectively the EPD problem, most of the conventional calculus methods rely on the assumption that the fuel cost characteristic of a generating unit is a continuous and convex function, resulting in inaccurate dispatch. This paper presents the design and application of efficient adaptive differential evolution (ADE algorithm for the solution of the economic power dispatch problem, where the non-convex characteristics of the generators, such us prohibited operating zones and ramp rate limits of the practical generator operation are considered. The 26 bus benchmark test system with 6 units having prohibited operating zones and ramp rate limits was used for testing and validation purposes. The results obtained demonstrate the effectiveness of the proposed method for solving the non-convex economic dispatch problem.

  19. The role of on-farm trees as an adaptation strategy to climate ...

    African Journals Online (AJOL)

    A study was conducted to investigate the role of on-farm tree as a long-term and sustainable adaptation strategy to climatic stresses in eight villages around Mkingu Nature Forest Reserve (MkNFR) in the. Eastern Arc Mountains of Tanzania. Specifically, the effects of climate change to peoples' livelihoods and the role of ...

  20. Perception, Mitigation and Adaptation Strategies of Irrigated Paddy Farmer Community to Face Climate Change

    Directory of Open Access Journals (Sweden)

    Siska Rasiska Suantapura

    2016-06-01

    Full Text Available Climate change has a real impact on the condition of agriculture in developing countries, including Indonesia. Irrigated paddy farmers are the ones really feeling the impact of climate change. Therefore, we need to understand the perceptions, mitigation and adaptation strategies of irrigated paddy farmer community to face climate change. The study is conducted in Indramayu and Tasikmalaya Regency in West Java by using descriptive survey method, regression analysis and path analysis through Structural Equation Modelling approach with Lisrel TM 8.5. The results showes that: (1 changes to climate variability affects the productivity of rice; (2 perception of irrigated paddy farmer community on climate change and its affects are influenced by internal and external factors; and (3 adaptation strategy are influenced by internal and external factors, whereas no mitigation strategy. Therefore, mitigation and adaptation strategies with site specific location are very necessary improving climate information services, increasing empowerment of farmers through field schools, and providing the provision of facilities that are practical and adaptive to climate.

  1. An extension of the classification of evolutionary singular strategies in Adaptive Dynamics

    NARCIS (Netherlands)

    Boldin, Barbara; Diekmann, Odo

    2014-01-01

    The existing classification of evolutionarily singular strategies in Adaptive Dynamics (Geritz et al. in Evol Ecol 12:35–57, 1998; Metz et al. in Stochastic and spatial structures of dynamical systems, pp 183–231, 1996) assumes an invasion exponent that is differentiable twice as a function of both

  2. Assessing climate change impacts and adaptation strategies for smallholder agricultural systems in Uganda

    NARCIS (Netherlands)

    Bagamba, F.; Bashaasha, B.; Claessens, L.F.G.; Antle, J.

    2012-01-01

    The debate on whether climate change will impact on peoples’ livelihoods and, hence, the need to act is essentially over and has instead shifted to the development of strategies needed by different regions and countries to adapt to climate change effects. However, there is still scanty information

  3. Adaptive and Qualitative Changes in Encoding Strategy with Experience: Evidence from the Test-Expectancy Paradigm

    Science.gov (United States)

    Finley, Jason R.; Benjamin, Aaron S.

    2012-01-01

    Three experiments demonstrated learners' abilities to adaptively and qualitatively accommodate their encoding strategies to the demands of an upcoming test. Stimuli were word pairs. In Experiment 1, test expectancy was induced for either cued recall (of targets given cues) or free recall (of targets only) across 4 study-test cycles of the same…

  4. Strategies for Controlling Item Exposure in Computerized Adaptive Testing with the Generalized Partial Credit Model

    Science.gov (United States)

    Davis, Laurie Laughlin

    2004-01-01

    Choosing a strategy for controlling item exposure has become an integral part of test development for computerized adaptive testing (CAT). This study investigated the performance of six procedures for controlling item exposure in a series of simulated CATs under the generalized partial credit model. In addition to a no-exposure control baseline…

  5. An interdisciplinary approach to identify adaptation strategies that enhance flood resilience and urban liveability

    DEFF Research Database (Denmark)

    Rogers, B. C.; Bertram, N.; Gunn, Alex

    This paper provides guidance on how to identify and design the most suitable climate adaptation strategies for enhancing the liveability and flood resilience of urban catchments. It presents findings from a case study of Elwood, a coastal Melbourne suburb regularly affected by flooding. The resea...

  6. Climate factors play a limited role for past adaptation strategies in West Africa

    DEFF Research Database (Denmark)

    Mertz, Ole; Mbow, Cheikh; Nielsen, Jonas Østergaard

    2010-01-01

    and pasture areas. Increases in pasture are also observed and caused by improved tenure in the driest zone. Adaptation strategies to declining crop production include 'prayer' and migration in the 400-500 mm zone; reforestation, migration, and government support in the 500-700 mm zone; and soil improvement...

  7. CRISPR-Cas: evolution of an RNA-based adaptive immunity system in prokaryotes.

    Science.gov (United States)

    Koonin, Eugene V; Makarova, Kira S

    2013-05-01

    The CRISPR-Cas (clustered regularly interspaced short palindromic repeats, CRISPR-associated genes) is an adaptive immunity system in bacteria and archaea that functions via a distinct self-non-self recognition mechanism that is partially analogous to the mechanism of eukaryotic RNA interference (RNAi). The CRISPR-Cas system incorporates fragments of virus or plasmid DNA into the CRISPR repeat cassettes and employs the processed transcripts of these spacers as guide RNAs to cleave the cognate foreign DNA or RNA. The Cas proteins, however, are not homologous to the proteins involved in RNAi and comprise numerous, highly diverged families. The majority of the Cas proteins contain diverse variants of the RNA recognition motif (RRM), a widespread RNA-binding domain. Despite the fast evolution that is typical of the cas genes, the presence of diverse versions of the RRM in most Cas proteins provides for a simple scenario for the evolution of the three distinct types of CRISPR-cas systems. In addition to several proteins that are directly implicated in the immune response, the cas genes encode a variety of proteins that are homologous to prokaryotic toxins that typically possess nuclease activity. The predicted toxins associated with CRISPR-Cas systems include the essential Cas2 protein, proteins of COG1517 that, in addition to a ligand-binding domain and a helix-turn-helix domain, typically contain different nuclease domains and several other predicted nucleases. The tight association of the CRISPR-Cas immunity systems with predicted toxins that, upon activation, would induce dormancy or cell death suggests that adaptive immunity and dormancy/suicide response are functionally coupled. Such coupling could manifest in the persistence state being induced and potentially providing conditions for more effective action of the immune system or in cell death being triggered when immunity fails.

  8. Dosimetric evaluation of three adaptive strategies for prostate cancer treatment including pelvic lymph nodes irradiation.

    Science.gov (United States)

    Cantin, Audrey; Gingras, Luc; Lachance, Bernard; Foster, William; Goudreault, Julie; Archambault, Louis

    2015-12-01

    The movements of the prostate relative to the pelvic lymph nodes during intensity-modulated radiation therapy treatment can limit margin reduction and affect the protection of the organs at risk (OAR). In this study, the authors performed an analysis of three adaptive treatment strategies that combine information from both bony and gold marker registrations. The robustness of those treatments against the interfraction prostate movements was evaluated. A retrospective study was conducted on five prostate cancer patients with 7-13 daily cone-beam CTs (CBCTs). The clinical target volumes (CTVs) consisting of pelvic lymph nodes, prostate, and seminal vesicles as well as the OARs were delineated on each CBCT and the initial CT. Three adaptive strategies were analyzed. Two of these methods relied on a two-step patient positioning at each fraction. First step: a bony registration was used to deliver the nodal CTV prescription. Second step: a gold marker registration was then used either to (1) complete the dose delivered to the prostate (complement); (2) or give almost the entire prescription to the prostate with a weak dose gradient between the targets to compensate for possible motions (gradient). The third method (COR) used a pool of precalculated plans based on images acquired at previous treatment fractions. At each new fraction, a plan is selected from that pool based on the daily position of prostate center-of-mass. The dosimetric comparison was conducted and results are presented with and without the systematic shift in the prostate position on the CT planning. The adaptive strategies were compared to the current clinical standard where all fractions are treated with the initial nonadaptive plan. The minimum daily prostate D95% is improved by 2%, 9%, and 6% for the complement, the gradient, and the COR approaches, respectively, compared to the nonadaptive method. The average nodal CTV D95% remains constant across the strategies, except for the gradient approach

  9. Dosimetric evaluation of three adaptive strategies for prostate cancer treatment including pelvic lymph nodes irradiation

    International Nuclear Information System (INIS)

    Cantin, Audrey; Gingras, Luc; Archambault, Louis; Lachance, Bernard; Foster, William; Goudreault, Julie

    2015-01-01

    Purpose: The movements of the prostate relative to the pelvic lymph nodes during intensity-modulated radiation therapy treatment can limit margin reduction and affect the protection of the organs at risk (OAR). In this study, the authors performed an analysis of three adaptive treatment strategies that combine information from both bony and gold marker registrations. The robustness of those treatments against the interfraction prostate movements was evaluated. Methods: A retrospective study was conducted on five prostate cancer patients with 7–13 daily cone-beam CTs (CBCTs). The clinical target volumes (CTVs) consisting of pelvic lymph nodes, prostate, and seminal vesicles as well as the OARs were delineated on each CBCT and the initial CT. Three adaptive strategies were analyzed. Two of these methods relied on a two-step patient positioning at each fraction. First step: a bony registration was used to deliver the nodal CTV prescription. Second step: a gold marker registration was then used either to (1) complete the dose delivered to the prostate (complement); (2) or give almost the entire prescription to the prostate with a weak dose gradient between the targets to compensate for possible motions (gradient). The third method (COR) used a pool of precalculated plans based on images acquired at previous treatment fractions. At each new fraction, a plan is selected from that pool based on the daily position of prostate center-of-mass. The dosimetric comparison was conducted and results are presented with and without the systematic shift in the prostate position on the CT planning. The adaptive strategies were compared to the current clinical standard where all fractions are treated with the initial nonadaptive plan. Results: The minimum daily prostate D 95% is improved by 2%, 9%, and 6% for the complement, the gradient, and the COR approaches, respectively, compared to the nonadaptive method. The average nodal CTV D 95% remains constant across the strategies

  10. An adaptive control strategy of converter based DG to maintain protection coordination in distribution system

    DEFF Research Database (Denmark)

    Su, Chi; Liu, Zhou; Chen, Zhe

    2014-01-01

    of network protection devices. As a protection measure commonly used in distribution network, recloser-fuse coordination could suffer from this impact. Research work has been conducted to deal with this problem by modifying the control strategy of the DG converters during faults. These solutions generally...... reduce the current output from the converters during faults so as to mitigate the influence on protection coordination. However, converter current reduction may not be necessary for all types of faults. This paper proposes a converter control strategy with adaptivity to different fault types and also non......-fault voltage drop events. This control strategy is validated by simulations in DIgSILENT PowerFactory....

  11. A multi-attribute approach to choosing adaptation strategies: Application to sea-level rise

    International Nuclear Information System (INIS)

    Smith, A.E.; Chu, H.Q.

    1994-01-01

    Selecting good adaptation strategies in anticipation of climate change is gaining increasing attention as it becomes increasingly clear that much of the likely change is already committed, and could not be avoided even with aggressive and immediate emissions reductions. Adaptation decision making will place special requirements on regional and local planners in the US and other countries, especially developing countries. Approaches, tools, and guidance will be useful to assist in an effective response to the challenge. This paper describes the value of using a multi-attribute approach for evaluating adaptation strategies and its implementation as a decision-support software tool to help planners understand and execute this approach. The multi-attribute approach described here explicitly addresses the fact that many aspects of the decision cannot be easily quantified, that future conditions are highly uncertain, and that there are issues of equity, flexibility, and coordination that may be as important to the decision as costs and benefits. The approach suggested also avoids trying to collapse information on all of the attributes to a single metric. Such metrics can obliterate insights about the nature of the trade-offs that must be made in choosing among very dissimilar types of responses to the anticipated threat of climate change. Implementation of such an approach requires management of much information, and an ability to easily manipulate its presentation while seeking acceptable trade-offs. The Adaptation Strategy Evaluator (ASE) was developed under funding from the US Environmental Protection Agency to provide user-friendly, PC-based guidance through the major steps of a multi-attribute evaluation. The initial application of ASE, and the focus of this paper, is adaptation to sea level rise. However, the approach can be easily adapted to any multi-attribute choice problem, including the range of other adaptation planning needs

  12. Trickle-down evolution: an approach to getting major evolutionary adaptive changes into textbooks and curricula.

    Science.gov (United States)

    Padian, Kevin

    2008-08-01

    Although contemporary high school and college textbooks of biology generally cover the principles and data of microevolution (genetic and populational change) and speciation rather well, coverage of what is known of the major changes in evolution (macroevolution), and how the evidence is understood is generally poor to nonexistent. It is critical to improve this because acceptance of evolution by the American public rests on the understanding of how we know what we know about the emergence of major new taxonomic groups, and about their adaptations, behaviors, and ecologies in geologic time. An efficient approach to this problem is to improve the illustrations in college textbooks to show the consilience of different lines of fossil, morphological, and molecular evidence mapped on phylogenies. Such "evograms" will markedly improve traditional illustrations of phylogenies, "menageries," and "companatomies." If "evograms" are installed at the college level, the basic principles and evidence of macroevolution will be more likely taught in K-12, thus providing an essential missing piece in biological education.

  13. Evolution of phenotypic clusters through competition and local adaptation along an environmental gradient.

    Science.gov (United States)

    Leimar, Olof; Doebeli, Michael; Dieckmann, Ulf

    2008-04-01

    We have analyzed the evolution of a quantitative trait in populations that are spatially extended along an environmental gradient, with gene flow between nearby locations. In the absence of competition, there is stabilizing selection toward a locally best-adapted trait that changes gradually along the gradient. According to traditional ideas, gradual spatial variation in environmental conditions is expected to lead to gradual variation in the evolved trait. A contrasting possibility is that the trait distribution instead breaks up into discrete clusters. Doebeli and Dieckmann (2003) argued that competition acting locally in trait space and geographical space can promote such clustering. We have investigated this possibility using deterministic population dynamics for asexual populations, analyzing our model numerically and through an analytical approximation. We examined how the evolution of clusters is affected by the shape of competition kernels, by the presence of Allee effects, and by the strength of gene flow along the gradient. For certain parameter ranges clustering was a robust outcome, and for other ranges there was no clustering. Our analysis shows that the shape of competition kernels is important for clustering: the sign structure of the Fourier transform of a competition kernel determines whether the kernel promotes clustering. Also, we found that Allee effects promote clustering, whereas gene flow can have a counteracting influence. In line with earlier findings, we could demonstrate that phenotypic clustering was favored by gradients of intermediate slope.

  14. Toolbox for uncertainty; Introduction of adaptive heuristics as strategies for project decision making

    DEFF Research Database (Denmark)

    Stingl, Verena; Geraldi, Joana

    2017-01-01

    This article presents adaptive heuristics as an alternative approach to navigate uncertainty in project decision-making. Adaptive heuristic are a class of simple decision strategies that have received only scant attention in project studies. Yet, they can strive in contexts of high uncertainty...... they are ‘ecologically rational’. The model builds on the individual definitions of ecological rationality and organizes them according to two types of uncertainty (‘knowable’ and ‘unknowable’). Decision problems and heuristics are furthermore grouped by decision task (choice and judgement). The article discusses...... and limited information, which are the typical project decision context. This article develops a conceptual model that supports a systematic connection between adaptive heuristics and project decisions. Individual adaptive heuristics succeed only in specific decision environments, in which...

  15. An adaptive synchronization strategy based on active control for demodulating message hidden in chaotic signals

    International Nuclear Information System (INIS)

    Tang Fang

    2008-01-01

    In the field of secure communication, it is very important to demodulate the message hidden in chaotic signals. In this paper, an adaptive synchronization strategy based on active control is proposed, which is used to design an active controller and an appropriate adaptive demodulator at the receiver to recover the transmitted message hidden in chaotic signals of a drive system. Based on Lyapunov stability theory, it is shown that the transmitted message can be theoretically recovered by using the proposed strategy. Numerical simulations based on the Chua's circuit are also presented to verify the effectiveness of the proposed strategy. In addition, it is shown via simulations that, by increasing the gain of the active controller the message error caused by the external noise and the discontinuous property of the message can be reduced

  16. Assessment of Model Predictive and Adaptive Glucose Control Strategies for People with Type 1 Diabetes

    DEFF Research Database (Denmark)

    Boiroux, Dimitri; Duun-Henriksen, Anne Katrine; Schmidt, Signe

    2014-01-01

    This paper addresses overnight blood glucose stabilization in people with type 1 diabetes using a Model Predictive Controller (MPC). We use a control strategy based on an adaptive ARMAX model in which we use a Recursive Extended Least Squares (RELS) method to estimate parameters of the stochastic...... and reduce the risk of hypoglycemia. We test our control strategies on a virtual clinic of 100 randomly generated patients with a representative inter-subject variability. This virtual clinic is based on the Hovorka model. We consider the case where only half of the meal bolus is administered at mealtime......, and the case where the insulin sensitivity varies during the night. The simulation results demonstrate that the adaptive control strategy can reduce the risks of hypoglycemia and hyperglycemia during the night....

  17. Epidemic propagation on adaptive coevolutionary networks with preferential local-world reconnecting strategy

    International Nuclear Information System (INIS)

    Song Yu-Rong; Jiang Guo-Ping; Gong Yong-Wang

    2013-01-01

    In the propagation of an epidemic in a population, individuals adaptively adjust their behavior to avoid the risk of an epidemic. Differently from existing studies where new links are established randomly, a local link is established preferentially in this paper. We propose a new preferentially reconnecting edge strategy depending on spatial distance (PR-SD). For the PR-SD strategy, the new link is established at random with probability p and in a shortest distance with the probability 1 − p. We establish the epidemic model on an adaptive network using Cellular Automata, and demonstrate the effectiveness of the proposed model by numerical simulations. The results show that the smaller the value of parameter p, the more difficult the epidemic spread is. The PR-SD strategy breaks long-range links and establishes as many short-range links as possible, which causes the network efficiency to decrease quickly and the propagation of the epidemic is restrained effectively. (general)

  18. Evolution of vertebrate adaptive immunity: immune cells and tissues, and AID/APOBEC cytidine deaminases.

    Science.gov (United States)

    Hirano, Masayuki

    2015-08-01

    All surviving jawed vertebrate representatives achieve diversity in immunoglobulin-based B and T cell receptors for antigen recognition through recombinatorial rearrangement of V(D)J segments. However, the extant jawless vertebrates, lampreys and hagfish, instead generate three types of variable lymphocyte receptors (VLRs) through a template-mediated combinatorial assembly of different leucine-rich repeat (LRR) sequences. The clonally diverse VLRB receptors are expressed by B-like lymphocytes, while the VLRA and VLRC receptors are expressed by lymphocyte lineages that resemble αβ and γδ T lymphocytes, respectively. These findings suggest that three basic types of lymphocytes, one B-like and two T-like, are an essential feature of vertebrate adaptive immunity. Around 500 million years ago, a common ancestor of jawed and jawless vertebrates evolved a genetic program for the development of prototypic lymphoid cells as a foundation for an adaptive immune system. This acquisition preceded the convergent evolution of alternative types of clonally diverse receptors for antigens in all vertebrates, as reviewed in this article. © 2015 WILEY Periodicals, Inc.

  19. Genome-wide signatures of complex introgression and adaptive evolution in the big cats

    Science.gov (United States)

    Figueiró, Henrique V.; Li, Gang; Trindade, Fernanda J.; Assis, Juliana; Pais, Fabiano; Fernandes, Gabriel; Santos, Sarah H. D.; Hughes, Graham M.; Komissarov, Aleksey; Antunes, Agostinho; Trinca, Cristine S.; Rodrigues, Maíra R.; Linderoth, Tyler; Bi, Ke; Silveira, Leandro; Azevedo, Fernando C. C.; Kantek, Daniel; Ramalho, Emiliano; Brassaloti, Ricardo A.; Villela, Priscilla M. S.; Nunes, Adauto L. V.; Teixeira, Rodrigo H. F.; Morato, Ronaldo G.; Loska, Damian; Saragüeta, Patricia; Gabaldón, Toni; Teeling, Emma C.; O’Brien, Stephen J.; Nielsen, Rasmus; Coutinho, Luiz L.; Oliveira, Guilherme; Murphy, William J.; Eizirik, Eduardo

    2017-01-01

    The great cats of the genus Panthera comprise a recent radiation whose evolutionary history is poorly understood. Their rapid diversification poses challenges to resolving their phylogeny while offering opportunities to investigate the historical dynamics of adaptive divergence. We report the sequence, de novo assembly, and annotation of the jaguar (Panthera onca) genome, a novel genome sequence for the leopard (Panthera pardus), and comparative analyses encompassing all living Panthera species. Demographic reconstructions indicated that all of these species have experienced variable episodes of population decline during the Pleistocene, ultimately leading to small effective sizes in present-day genomes. We observed pervasive genealogical discordance across Panthera genomes, caused by both incomplete lineage sorting and complex patterns of historical interspecific hybridization. We identified multiple signatures of species-specific positive selection, affecting genes involved in craniofacial and limb development, protein metabolism, hypoxia, reproduction, pigmentation, and sensory perception. There was remarkable concordance in pathways enriched in genomic segments implicated in interspecies introgression and in positive selection, suggesting that these processes were connected. We tested this hypothesis by developing exome capture probes targeting ~19,000 Panthera genes and applying them to 30 wild-caught jaguars. We found at least two genes (DOCK3 and COL4A5, both related to optic nerve development) bearing significant signatures of interspecies introgression and within-species positive selection. These findings indicate that post-speciation admixture has contributed genetic material that facilitated the adaptive evolution of big cat lineages. PMID:28776029

  20. Protein domain evolution is associated with reproductive diversification and adaptive radiation in the genus Eucalyptus.

    Science.gov (United States)

    Kersting, Anna R; Mizrachi, Eshchar; Bornberg-Bauer, Erich; Myburg, Alexander A

    2015-06-01

    Eucalyptus is a pivotal genus within the rosid order Myrtales with distinct geographic history and adaptations. Comparative analysis of protein domain evolution in the newly sequenced Eucalyptus grandis genome and other rosid lineages sheds light on the adaptive mechanisms integral to the success of this genus of woody perennials. We reconstructed the ancestral domain content to elucidate the gain, loss and expansion of protein domains and domain arrangements in Eucalyptus in the context of rosid phylogeny. We used functional gene ontology (GO) annotation of genes to investigate the possible biological and evolutionary consequences of protein domain expansion. We found that protein modulation within the angiosperms occurred primarily on the level of expansion of certain domains and arrangements. Using RNA-Seq data from E. grandis, we showed that domain expansions have contributed to tissue-specific expression of tandemly duplicated genes. Our results indicate that tandem duplication of genes, a key feature of the Eucalyptus genome, has played an important role in the expansion of domains, particularly in proteins related to the specialization of reproduction and biotic and abiotic interactions affecting root and floral biology, and that tissue-specific expression of proteins with expanded domains has facilitated subfunctionalization in domain families. © 2014 University of Pretoria New Phytologist © 2014 New Phytologist Trust.

  1. The ALICE-HMPID Detector Control System: Its evolution towards an expert and adaptive system

    Science.gov (United States)

    De Cataldo, G.; Franco, A.; Pastore, C.; Sgura, I.; Volpe, G.

    2011-05-01

    The High Momentum Particle IDentification (HMPID) detector is a proximity focusing Ring Imaging Cherenkov (RICH) for charged hadron identification. The HMPID is based on liquid C 6F 14 as the radiator medium and on a 10 m 2 CsI coated, pad segmented photocathode of MWPCs for UV Cherenkov photon detection. To ensure full remote control, the HMPID is equipped with a detector control system (DCS) responding to industrial standards for robustness and reliability. It has been implemented using PVSS as Slow Control And Data Acquisition (SCADA) environment, Programmable Logic Controller as control devices and Finite State Machines for modular and automatic command execution. In the perspective of reducing human presence at the experiment site, this paper focuses on DCS evolution towards an expert and adaptive control system, providing, respectively, automatic error recovery and stable detector performance. HAL9000, the first prototype of the HMPID expert system, is then presented. Finally an analysis of the possible application of the adaptive features is provided.

  2. The ALICE-HMPID Detector Control System: Its evolution towards an expert and adaptive system

    International Nuclear Information System (INIS)

    De Cataldo, G.; Franco, A.; Pastore, C.; Sgura, I.; Volpe, G.

    2011-01-01

    The High Momentum Particle IDentification (HMPID) detector is a proximity focusing Ring Imaging Cherenkov (RICH) for charged hadron identification. The HMPID is based on liquid C 6 F 14 as the radiator medium and on a 10 m 2 CsI coated, pad segmented photocathode of MWPCs for UV Cherenkov photon detection. To ensure full remote control, the HMPID is equipped with a detector control system (DCS) responding to industrial standards for robustness and reliability. It has been implemented using PVSS as Slow Control And Data Acquisition (SCADA) environment, Programmable Logic Controller as control devices and Finite State Machines for modular and automatic command execution. In the perspective of reducing human presence at the experiment site, this paper focuses on DCS evolution towards an expert and adaptive control system, providing, respectively, automatic error recovery and stable detector performance. HAL9000, the first prototype of the HMPID expert system, is then presented. Finally an analysis of the possible application of the adaptive features is provided.

  3. Assessment of the effectiveness of participatory developed adaptation strategies for HCMC

    Science.gov (United States)

    Lasage, R.; Veldkamp, T. I. E.; de Moel, H.; Van, T. C.; Phi, H. L.; Vellinga, P.; Aerts, J. C. J. H.

    2014-01-01

    Coastal cities are vulnerable to flooding, and flood risk to coastal cities will increase due to sea-level rise. Moreover, especially Asian cities are subject to considerable population growth and associated urban developments, increasing this risk even more. Empirical data on vulnerability and the cost and benefits of flood risk reducing measures are therefore paramount for sustainable development of these cities. This paper presents an approach to explore the impacts of sea level rise and socio-economic developments on flood risk for the flood prone District 4 in Ho Chi Minh City, Vietnam, and to develop and evaluate the effects of different adaptation strategies (new levees, dry- and wet flood proofing of buildings). A flood damage model was developed to simulate current and future flood risk using the results from a household survey to establish stage-damage curves for residential buildings. the model has been used to assess the effects of several participatory developed adaptation strategies to reduce flood risk, expressed in Expected Annual Damage (EAD). Adaptation strategies were evaluated assuming combinations of both sea level scenarios and land use scenarios. Together with information on costs of these strategies, we calculated the benefit-cost ratio and net present value for the adaptation strategies until 2100, taking into account depreciation rates of 2.5% and 5%. The results of this modeling study indicate that the current flood risk in District 4 is 0.31 million USD yr-1, increasing up to 0.78 million USD yr-1 in 2100. The net present value and benefit-cost ratios using a discount rate of 5% range from USD -107 to -1.5 million, and from 0.086 to 0.796 for the different strategies. Using a discount rate of 2.5% leads to an increase in both net present value and benefit cost ratio. The adaptation strategies wet proofing and dry proofing generate the best results using these economic indicators. The information on different strategies will be used by

  4. Adaptive evolution of simian immunodeficiency viruses isolated from two conventional progressor macaques with neuroaids

    Energy Technology Data Exchange (ETDEWEB)

    Foley, Brian T [Los Alamos National Laboratory; Korber, Bette T [Los Alamos National Laboratory

    2008-01-01

    Simian immunodeficiency virus infection of macaques may result in neuroAIDS, a feature more commonly observed in macaques with rapid progressive disease than in those with conventional disease. This is the first report of two conventional progressors (H631 and H636) with encephalitis in rhesus macaques inoculated with a derivative of SIVsmES43-3. Phylogenetic analyses of viruses isolated from the cerebral spinal fluid (CSF) and plasma from both animals demonstrated tissue compartmentalization. Additionally, virus from the central nervous system (CNS) was able to infect primary macaque monocyte-derived macrophages more efficiently than virus from plasma. Conversely, virus isolated from plasma was able to replicate better in peripheral blood mononuclear cells than virus from CNS. We speculate that these viruses were under different selective pressures in their separate compartments. Furthermore, these viruses appear to have undergone adaptive evolution to preferentially replicate in their respective cell targets. Analysis of the number of potential N-linked glycosylation sites (PNGS) in gp160 showed that there was a statistically significant loss of PNGS in viruses isolated from CNS in both macaques compared to SIVsmE543-3. Moreover, virus isolated from the brain in H631, had statistically significant loss of PNGS compared to virus isolated from CSF and plasma of the same animal. It is possible that the brain isolate may have adapted to decrease the number of PNGS given that humoral immune selection pressure is less likely to be encountered in the brain. These viruses provide a relevant model to study the adaptations required for SIV to induce encephalitis.

  5. Socio-economic vulnerability of coastal communities in southern Thailand: the development of adaptation strategies

    Science.gov (United States)

    Willroth, P.; Massmann, F.; Wehrhahn, R.; Revilla Diez, J.

    2012-08-01

    The tsunami of December 2004 impacted large areas of Thailand's coastline and caused severe human and economic losses. The recovery period revealed differences in the vulnerabilities of communities affected. An understanding of the causal factors of vulnerability is crucial for minimising the negative effects of future threats and developing adaptive capacities. This paper analyses the vulnerabilities and the development of adaptation strategies in the booming tourist area of Khao Lak and in the predominantly fishing and agricultural area of Ban Nam Khem through a comprehensive vulnerability framework. The results show that social networks played a crucial role in coping with the disaster. Social cohesion is important for strengthening the community and developing successful adaptation strategies. The development of tourism and the turning away from traditional activities have a significant positive influence on the income situation, but create a dependency on a single business sector. It could be shown that households generating their income in the tourism sector were vulnerable unless they had diversified their income previously. Income diversification decreased the vulnerability in the study areas. Adaptation strategies and processes developed in the aftermath clearly address these issues.

  6. Evolution of Escherichia coli to 42 °C and Subsequent Genetic Engineering Reveals Adaptive Mechanisms and Novel Mutations

    DEFF Research Database (Denmark)

    Sandberg, Troy E.; Pedersen, Margit; LaCroix, Ryan A.

    2014-01-01

    Adaptive laboratory evolution (ALE) has emerged as a valuable method by which to investigate microbial adaptation to a desired environment. Here, we performed ALE to 42 °C of ten parallel populations of Escherichia coli K-12 MG1655 grown in glucose minimal media. Tightly controlled experimental c...... targets for additional ameliorating mutations. Overall, the results of this study provide insight into the adaptation process and yield lessons important for the future implementation of ALE as a tool for scientific research and engineering....

  7. Cautious but Committed: Moving Toward Adaptive Planning and Operation Strategies for Renewable Energy's Wildlife Implications

    Science.gov (United States)

    Köppel, Johann; Dahmen, Marie; Helfrich, Jennifer; Schuster, Eva; Bulling, Lea

    2014-10-01

    Wildlife planning for renewable energy must cope with the uncertainties of potential wildlife impacts. Unfortunately, the environmental policies which instigate renewable energy and those which protect wildlife are not coherently aligned—creating a green versus green dilemma. Thus, climate mitigation efforts trigger renewable energy development, but then face substantial barriers from biodiversity protection instruments and practices. This article briefly reviews wind energy and wildlife interactions, highlighting the lively debated effects on bats. Today, planning and siting of renewable energy are guided by the precautionary principle in an attempt to carefully address wildlife challenges. However, this planning attitude creates limitations as it struggles to negotiate the aforementioned green versus green dilemma. More adaptive planning and management strategies and practices hold the potential to reconcile these discrepancies to some degree. This adaptive approach is discussed using facets of case studies from policy, planning, siting, and operational stages of wind energy in Germany and the United States, with one case showing adaptive planning in action for solar energy as well. This article attempts to highlight the benefits of more adaptive approaches as well as the possible shortcomings, such as reduced planning security for renewable energy developers. In conclusion, these studies show that adaptive planning and operation strategies can be designed to supplement and enhance the precautionary principle in wildlife planning for green energy.

  8. Cautious but committed: moving toward adaptive planning and operation strategies for renewable energy's wildlife implications.

    Science.gov (United States)

    Köppel, Johann; Dahmen, Marie; Helfrich, Jennifer; Schuster, Eva; Bulling, Lea

    2014-10-01

    Wildlife planning for renewable energy must cope with the uncertainties of potential wildlife impacts. Unfortunately, the environmental policies which instigate renewable energy and those which protect wildlife are not coherently aligned-creating a green versus green dilemma. Thus, climate mitigation efforts trigger renewable energy development, but then face substantial barriers from biodiversity protection instruments and practices. This article briefly reviews wind energy and wildlife interactions, highlighting the lively debated effects on bats. Today, planning and siting of renewable energy are guided by the precautionary principle in an attempt to carefully address wildlife challenges. However, this planning attitude creates limitations as it struggles to negotiate the aforementioned green versus green dilemma. More adaptive planning and management strategies and practices hold the potential to reconcile these discrepancies to some degree. This adaptive approach is discussed using facets of case studies from policy, planning, siting, and operational stages of wind energy in Germany and the United States, with one case showing adaptive planning in action for solar energy as well. This article attempts to highlight the benefits of more adaptive approaches as well as the possible shortcomings, such as reduced planning security for renewable energy developers. In conclusion, these studies show that adaptive planning and operation strategies can be designed to supplement and enhance the precautionary principle in wildlife planning for green energy.

  9. Optimal Decision Fusion for Urban Land-Use/Land-Cover Classification Based on Adaptive Differential Evolution Using Hyperspectral and LiDAR Data

    Directory of Open Access Journals (Sweden)

    Yanfei Zhong

    2017-08-01

    Full Text Available Hyperspectral images and light detection and ranging (LiDAR data have, respectively, the high spectral resolution and accurate elevation information required for urban land-use/land-cover (LULC classification. To combine the respective advantages of hyperspectral and LiDAR data, this paper proposes an optimal decision fusion method based on adaptive differential evolution, namely ODF-ADE, for urban LULC classification. In the ODF-ADE framework the normalized difference vegetation index (NDVI, gray-level co-occurrence matrix (GLCM and digital surface model (DSM are extracted to form the feature map. The three different classifiers of the maximum likelihood classifier (MLC, support vector machine (SVM and multinomial logistic regression (MLR are used to classify the extracted features. To find the optimal weights for the different classification maps, weighted voting is used to obtain the classification result and the weights of each classification map are optimized by the differential evolution algorithm which uses a self-adaptive strategy to obtain the parameter adaptively. The final classification map is obtained after post-processing based on conditional random fields (CRF. The experimental results confirm that the proposed algorithm is very effective in urban LULC classification.

  10. Reactive power and voltage control strategy based on dynamic and adaptive segment for DG inverter

    Science.gov (United States)

    Zhai, Jianwei; Lin, Xiaoming; Zhang, Yongjun

    2018-03-01

    The inverter of distributed generation (DG) can support reactive power to help solve the problem of out-of-limit voltage in active distribution network (ADN). Therefore, a reactive voltage control strategy based on dynamic and adaptive segment for DG inverter is put forward to actively control voltage in this paper. The proposed strategy adjusts the segmented voltage threshold of Q(U) droop curve dynamically and adaptively according to the voltage of grid-connected point and the power direction of adjacent downstream line. And then the reactive power reference of DG inverter can be got through modified Q(U) control strategy. The reactive power of inverter is controlled to trace the reference value. The proposed control strategy can not only control the local voltage of grid-connected point but also help to maintain voltage within qualified range considering the terminal voltage of distribution feeder and the reactive support for adjacent downstream DG. The scheme using the proposed strategy is compared with the scheme without the reactive support of DG inverter and the scheme using the Q(U) control strategy with constant segmented voltage threshold. The simulation results suggest that the proposed method has a significant improvement on solving the problem of out-of-limit voltage, restraining voltage variation and improving voltage quality.

  11. Social and natural sciences differ in their research strategies, adapted to work for different knowledge landscapes.

    Science.gov (United States)

    Jaffe, Klaus

    2014-01-01

    Do different fields of knowledge require different research strategies? A numerical model exploring different virtual knowledge landscapes, revealed two diverging optimal search strategies. Trend following is maximized when the popularity of new discoveries determine the number of individuals researching it. This strategy works best when many researchers explore few large areas of knowledge. In contrast, individuals or small groups of researchers are better in discovering small bits of information in dispersed knowledge landscapes. Bibliometric data of scientific publications showed a continuous bipolar distribution of these strategies, ranging from natural sciences, with highly cited publications in journals containing a large number of articles, to the social sciences, with rarely cited publications in many journals containing a small number of articles. The natural sciences seem to adapt their research strategies to landscapes with large concentrated knowledge clusters, whereas social sciences seem to have adapted to search in landscapes with many small isolated knowledge clusters. Similar bipolar distributions were obtained when comparing levels of insularity estimated by indicators of international collaboration and levels of country-self citations: researchers in academic areas with many journals such as social sciences, arts and humanities, were the most isolated, and that was true in different regions of the world. The work shows that quantitative measures estimating differences between academic disciplines improve our understanding of different research strategies, eventually helping interdisciplinary research and may be also help improve science policies worldwide.

  12. Workshop approach for developing climate change adaptation strategies and actions for natural resource management agencies in the United States

    Science.gov (United States)

    Jessica E. Halofsky; David L Peterson; Michael J. Furniss; Linda A. Joyce; Constance I. Millar; Ronald P. Neilson

    2011-01-01

    Concrete ways to adapt to climate change are needed to help land-management agencies take steps to incorporate climate change into management and take advantage of opportunities to balance the negative effects of climate change. Because the development of adaptation tools and strategies is at an early stage, it is important that ideas and strategies are disseminated...

  13. Global Rebalancing of Cellular Resources by Pleiotropic Point Mutations Illustrates a Multi-scale Mechanism of Adaptive Evolution

    DEFF Research Database (Denmark)

    Utrilla, José; O'Brien, Edward J.; Chen, Ke

    2016-01-01

    Pleiotropic regulatory mutations affect diverse cellular processes, posing a challenge to our understanding of genotype-phenotype relationships across multiple biological scales. Adaptive laboratory evolution (ALE) allows for such mutations to be found and characterized in the context of clear se...

  14. An adaptive radiotherapy planning strategy for bladder cancer using deformation vector fields

    International Nuclear Information System (INIS)

    Vestergaard, Anne; Kallehauge, Jesper Folsted; Petersen, Jørgen Breede Baltzer; Høyer, Morten; Søndergaard, Jimmi; Muren, Ludvig Paul

    2014-01-01

    Purpose: Adaptive radiotherapy (ART) has considerable potential in treatment of bladder cancer due to large inter-fractional changes in shape and size of the target. The aim of this study was to compare our clinically applied method for plan library creation that involves manual bladder delineations (Clin-ART) with a method using the deformation vector fields (DVFs) resulting from intensity-based deformable image registrations (DVF-based ART). Materials and methods: The study included thirteen patients with urinary bladder cancer who had daily cone beam CTs (CBCTs) acquired for set-up. In both ART strategies investigated, three plan selection volumes were generated using the CBCTs from the first four fractions; in Clin-ART boolean combinations of delineated bladders were used, while the DVF-based strategy applied combinations of the mean and standard deviation of patient-specific DVFs. The volume ratios (VRs) of the course-averaged PTV for the two ART strategies relative the non-adaptive PTV were calculated. Results: Both Clin-ART and DVF-based ART considerably reduced the course-averaged PTV, compared to non-adaptive RT. The VR for DVF-based ART was lower than for Clin-ART (0.65 vs. 0.73; p < 0.01). Conclusions: DVF-based ART for bladder irradiation has a considerable normal tissue sparing potential surpassing our already highly conformal clinically applied ART strategy

  15. Adaptive Control Based Harvesting Strategy for a Predator-Prey Dynamical System.

    Science.gov (United States)

    Sen, Moitri; Simha, Ashutosh; Raha, Soumyendu

    2018-04-23

    This paper deals with designing a harvesting control strategy for a predator-prey dynamical system, with parametric uncertainties and exogenous disturbances. A feedback control law for the harvesting rate of the predator is formulated such that the population dynamics is asymptotically stabilized at a positive operating point, while maintaining a positive, steady state harvesting rate. The hierarchical block strict feedback structure of the dynamics is exploited in designing a backstepping control law, based on Lyapunov theory. In order to account for unknown parameters, an adaptive control strategy has been proposed in which the control law depends on an adaptive variable which tracks the unknown parameter. Further, a switching component has been incorporated to robustify the control performance against bounded disturbances. Proofs have been provided to show that the proposed adaptive control strategy ensures asymptotic stability of the dynamics at a desired operating point, as well as exact parameter learning in the disturbance-free case and learning with bounded error in the disturbance prone case. The dynamics, with uncertainty in the death rate of the predator, subjected to a bounded disturbance has been simulated with the proposed control strategy.

  16. An adaptive radiotherapy planning strategy for bladder cancer using deformation vector fields.

    Science.gov (United States)

    Vestergaard, Anne; Kallehauge, Jesper Folsted; Petersen, Jørgen Breede Baltzer; Høyer, Morten; Søndergaard, Jimmi; Muren, Ludvig Paul

    2014-09-01

    Adaptive radiotherapy (ART) has considerable potential in treatment of bladder cancer due to large inter-fractional changes in shape and size of the target. The aim of this study was to compare our clinically applied method for plan library creation that involves manual bladder delineations (Clin-ART) with a method using the deformation vector fields (DVFs) resulting from intensity-based deformable image registrations (DVF-based ART). The study included thirteen patients with urinary bladder cancer who had daily cone beam CTs (CBCTs) acquired for set-up. In both ART strategies investigated, three plan selection volumes were generated using the CBCTs from the first four fractions; in Clin-ART boolean combinations of delineated bladders were used, while the DVF-based strategy applied combinations of the mean and standard deviation of patient-specific DVFs. The volume ratios (VRs) of the course-averaged PTV for the two ART strategies relative the non-adaptive PTV were calculated. Both Clin-ART and DVF-based ART considerably reduced the course-averaged PTV, compared to non-adaptive RT. The VR for DVF-based ART was lower than for Clin-ART (0.65 vs. 0.73; p<0.01). DVF-based ART for bladder irradiation has a considerable normal tissue sparing potential surpassing our already highly conformal clinically applied ART strategy. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

  17. Strategies for adding adaptive learning mechanisms to rule-based diagnostic expert systems

    Science.gov (United States)

    Stclair, D. C.; Sabharwal, C. L.; Bond, W. E.; Hacke, Keith

    1988-01-01

    Rule-based diagnostic expert systems can be used to perform many of the diagnostic chores necessary in today's complex space systems. These expert systems typically take a set of symptoms as input and produce diagnostic advice as output. The primary objective of such expert systems is to provide accurate and comprehensive advice which can be used to help return the space system in question to nominal operation. The development and maintenance of diagnostic expert systems is time and labor intensive since the services of both knowledge engineer(s) and domain expert(s) are required. The use of adaptive learning mechanisms to increment evaluate and refine rules promises to reduce both time and labor costs associated with such systems. This paper describes the basic adaptive learning mechanisms of strengthening, weakening, generalization, discrimination, and discovery. Next basic strategies are discussed for adding these learning mechanisms to rule-based diagnostic expert systems. These strategies support the incremental evaluation and refinement of rules in the knowledge base by comparing the set of advice given by the expert system (A) with the correct diagnosis (C). Techniques are described for selecting those rules in the in the knowledge base which should participate in adaptive learning. The strategies presented may be used with a wide variety of learning algorithms. Further, these strategies are applicable to a large number of rule-based diagnostic expert systems. They may be used to provide either immediate or deferred updating of the knowledge base.

  18. Adaptive Treatment Strategies in Youth Mental Health: A Commentary on Advantages, Challenges, and Potential Directions.

    Science.gov (United States)

    Sherrill, Joel T

    2016-01-01

    This commentary underscores the importance and potential of the research approaches and intervention strategies described in the JCCAP special issue on the Science of Adaptive Treatment Strategies in Child and Adolescent Mental Health for addressing the widely observed heterogeneity in response to even our most promising research-informed interventions. First, the commentary briefly summarizes the advantages of these approaches and highlights how these programs of research are responsive to widely agreed-upon calls for more personalized, prescriptive interventions. Next, the commentary briefly discusses key common challenges and gaps in our knowledge that might be addressed to advance the development, testing, and implementation of adaptive intervention strategies. For example, research to identify robust moderators that might serve as potential tailoring variables for initial assignment and sequencing of interventions, efforts to operationalize surrogate endpoints for early identification of individuals who are unlikely to respond to first-line interventions, and research that helps define what constitutes an adequate exposure (i.e., dose) or response threshold (e.g., response that suggests the need to intensify, switch, or augment interventions) would inform decision rules for adaptive algorithms. The commentary concludes with a discussion of potential strategies and current initiatives that might ultimately help facilitate research on more targeted, prescriptive approaches to intervening, including efforts to encourage investigators to use common data elements, to share and integrate data across trials, and to employ a more mechanism-based approach to intervention development and testing.

  19. A new strategy for online adaptive prostate radiotherapy based on cone-beam CT

    International Nuclear Information System (INIS)

    Boggula, Ramesh; Lorenz, Friedlieb; Lohr, Frank; Wolff, Dirk; Boda-Heggemann, Judit; Hesser, Juergen; Wenz, Frederik; Wertz, Hansjoerg

    2009-01-01

    Interfractional organ motion and patient positioning errors during prostate radiotherapy can have deleterious clinical consequences. It has become clinical practice to re-position the patient with image-guided translational position correction before each treatment to compensate for those errors. However, tilt errors can only be corrected with table corrections in six degrees of freedom or ''full'' adaptive treatment planning strategies. Organ shape deformations can only be corrected by ''full'' plan adaptation. This study evaluates the potential of instant treatment plan adaptation (fast isodose line adaptation with real-time dose manipulating tools) based on cone-beam CT (CBCT) to further improve treatment quality. Using in-house software, CBCTs were modified to approximate a correct density calibration. To evaluate the dosimetric accuracy, dose distributions based on CBCTs were compared with dose distributions calculated on conventional planning CTs (PCT) for four datasets (one inhomogeneous phantom, three patient datasets). To determine the potential dosimetric benefit of a ''full'' plan adaptation over translational position correction, dose distributions were re-optimized using graphical ''online'' dose modification tools for three additional patients' CT-datasets with a substantially distended rectum while the original plans have been created with an empty rectum (single treatment fraction estimates). Absolute dose deviations of up to 51% in comparison to the PCT were observed when uncorrected CBCTs were used for replanning. After density calibration of the CBCTs, 97% of the dose deviations were ≤3% (gamma index: 3%/3 mm). Translational position correction restored the PTV dose (D 95 ) to 73% of the corresponding dose of the reference plan. After plan adaptation, larger improvements of dose restoration to 95% were observed. Additionally, the rectal dose (D 30 ) was further decreased by 42 percentage points (mean of three patient datasets). An accurate dose

  20. The Black Queen Hypothesis: evolution of dependencies through adaptive gene loss.

    Science.gov (United States)

    Morris, J Jeffrey; Lenski, Richard E; Zinser, Erik R

    2012-01-01

    Reductive genomic evolution, driven by genetic drift, is common in endosymbiotic bacteria. Genome reduction is less common in free-living organisms, but it has occurred in the numerically dominant open-ocean bacterioplankton Prochlorococcus and "Candidatus Pelagibacter," and in these cases the reduction appears to be driven by natural selection rather than drift. Gene loss in free-living organisms may leave them dependent on cooccurring microbes for lost metabolic functions. We present the Black Queen Hypothesis (BQH), a novel theory of reductive evolution that explains how selection leads to such dependencies; its name refers to the queen of spades in the game Hearts, where the usual strategy is to avoid taking this card. Gene loss can provide a selective advantage by conserving an organism's limiting resources, provided the gene's function is dispensable. Many vital genetic functions are leaky, thereby unavoidably producing public goods that are available to the entire community. Such leaky functions are thus dispensable for individuals, provided they are not lost entirely from the community. The BQH predicts that the loss of a costly, leaky function is selectively favored at the individual level and will proceed until the production of public goods is just sufficient to support the equilibrium community; at that point, the benefit of any further loss would be offset by the cost. Evolution in accordance with the BQH thus generates "beneficiaries" of reduced genomic content that are dependent on leaky "helpers," and it may explain the observed nonuniversality of prototrophy, stress resistance, and other cellular functions in the microbial world.

  1. Directed evolution combined with synthetic biology strategies expedite semi-rational engineering of genes and genomes.

    Science.gov (United States)

    Kang, Zhen; Zhang, Junli; Jin, Peng; Yang, Sen

    2015-01-01

    Owing to our limited understanding of the relationship between sequence and function and the interaction between intracellular pathways and regulatory systems, the rational design of enzyme-coding genes and de novo assembly of a brand-new artificial genome for a desired functionality or phenotype are difficult to achieve. As an alternative approach, directed evolution has been widely used to engineer genomes and enzyme-coding genes. In particular, significant developments toward DNA synthesis, DNA assembly (in vitro or in vivo), recombination-mediated genetic engineering, and high-throughput screening techniques in the field of synthetic biology have been matured and widely adopted, enabling rapid semi-rational genome engineering to generate variants with desired properties. In this commentary, these novel tools and their corresponding applications in the directed evolution of genomes and enzymes are discussed. Moreover, the strategies for genome engineering and rapid in vitro enzyme evolution are also proposed.

  2. The diversity of gendered adaptation strategies to climate change of Indian farmers: A feminist intersectional approach.

    Science.gov (United States)

    Ravera, Federica; Martín-López, Berta; Pascual, Unai; Drucker, Adam

    2016-12-01

    This paper examines climate change adaptation and gender issues through an application of a feminist intersectional approach. This approach permits the identification of diverse adaptation responses arising from the existence of multiple and fragmented dimensions of identity (including gender) that intersect with power relations to shape situation-specific interactions between farmers and ecosystems. Based on results from contrasting research cases in Bihar and Uttarakhand, India, this paper demonstrates, inter alia, that there are geographically determined gendered preferences and adoption strategies regarding adaptation options and that these are influenced by the socio-ecological context and institutional dynamics. Intersecting identities, such as caste, wealth, age and gender, influence decisions and reveal power dynamics and negotiation within the household and the community, as well as barriers to adaptation among groups. Overall, the findings suggest that a feminist intersectional approach does appear to be useful and worth further exploration in the context of climate change adaptation. In particular, future research could benefit from more emphasis on a nuanced analysis of the intra-gender differences that shape adaptive capacity to climate change.

  3. Establishment of an indicator concept for the German strategy on adaptation to climate change

    Energy Technology Data Exchange (ETDEWEB)

    Schoenthaler, Konstanze; Andrian-Werburg, Stefan von; Wulfert, Katrin [Bosch und Partner GmbH, Muenchen (Germany); Luthardt, Vera; Kreinsen, Beatrice; Schultz-Sternberg, R.; Hommel, Robert [Hochschule fuer Nachhaltige Entwicklung Eberswalde (Germany)

    2010-11-15

    Even if we succeed in achieving the EU target of reducing global warming to 2 C, it will be absolutely essential to adapt to changing climatic conditions. The greenhouse gases currently present in the atmosphere will influence the climate in coming decades. The day on which it is quite clear which climatic scenario prevails, so that it is possible to model all relevant processes down to regional level, will be the day on which it is too late to adapt to the actual scenario. Our endeavours to adapt to climate change do not mean, however, that we can neglect to take measures in order to reduce the output of greenhouse gases. It is important to remember that on their own, neither adaptation nor mitigation can prevent the grave impacts resulting from climate change. In fact, they complement each other meaningfully thus helping to alleviate the risks of climate change. On 17th December 2008 the German Federal Cabinet adopted the DAS (German Strategy for the Adaptation to Climate Change), (Bundesregierung 2008). The DAS has created the framework for adapting to the consequences of climate change in Germany. First and fore-most, the DAS contributes its guidelines at Federal level, to provide a guideline for agents at other levels. The Strategy lays the foundation for a medium-term process. In conjunction with the individual Federal States and other groups representing various sectors of society, the Strategy provides a step-by-step assessment of the risks of climate change. Furthermore, it states the potential requirements for action, and defines the appropriate goals and potential adaptation measures to be developed and implemented in this process. In due course, the Federal Environment Agency (UBA) will design a comprehensive set of tools to support and advance the DAS. An integral part of this will be the Special Information System 'Adaptation' (FISKA) and an Indicator System to aid adaptation. The latter is one of the key tasks identified for the DAS. As far

  4. Application of evolution strategy algorithm for optimization of a single-layer sound absorber

    Directory of Open Access Journals (Sweden)

    Morteza Gholamipoor

    2014-12-01

    Full Text Available Depending on different design parameters and limitations, optimization of sound absorbers has always been a challenge in the field of acoustic engineering. Various methods of optimization have evolved in the past decades with innovative method of evolution strategy gaining more attention in the recent years. Based on their simplicity and straightforward mathematical representations, single-layer absorbers have been widely used in both engineering and industrial applications and an optimized design for these absorbers has become vital. In the present study, the method of evolution strategy algorithm is used for optimization of a single-layer absorber at both a particular frequency and an arbitrary frequency band. Results of the optimization have been compared against different methods of genetic algorithm and penalty functions which are proved to be favorable in both effectiveness and accuracy. Finally, a single-layer absorber is optimized in a desired range of frequencies that is the main goal of an industrial and engineering optimization process.

  5. Evolution strategies and multi-objective optimization of permanent magnet motor

    DEFF Research Database (Denmark)

    Andersen, Søren Bøgh; Santos, Ilmar

    2012-01-01

    When designing a permanent magnet motor, several geometry and material parameters are to be defined. This is not an easy task, as material properties and magnetic fields are highly non-linear and the design of a motor is therefore often an iterative process. From an engineering point of view, we...... of evolution strategies, ES to effectively design and optimize parameters of permanent magnet motors. Single as well as multi-objective optimization procedures are carried out. A modified way of creating the strategy parameters for the ES algorithm is also proposed and has together with the standard ES...

  6. Evolution and adaptation of the pandemic A/H1N1 2009 influenza virus

    Directory of Open Access Journals (Sweden)

    Ducatez MF

    2011-07-01

    Full Text Available Mariette F Ducatez, Thomas P Fabrizio, Richard J WebbyDepartment of Infectious Diseases, St Jude Children's Research Hospital, Memphis, TN, USAAbstract: The emergence of the 2009 H1N1 pandemic influenza virus [A(H1N1pdm09] has provided the public health community with many challenges, but also the scientific community with an opportunity to monitor closely its evolution through the processes of drift and shift. To date, and despite having circulated in humans for nearly two years, little antigenic variation has been observed in the A(H1N1pdm09 viruses. However, as the A(H1N1pdm09 virus continues to circulate and the immunologic pressure within the human population increases, future antigenic change is almost a certainty. Several coinfections of A(H1N1pdm09 and seasonal A(H1N1 or A(H3N2 viruses have been observed, but no reassortant viruses have been described in humans, suggesting a lack of fitness of reassortant viruses or a lack of opportunities for interaction of different viral lineages. In contrast, multiple reassortment events have been detected in swine populations between A(H1N1 pdm09 and other endemic swine viruses. Somewhat surprisingly, many of the well characterized influenza virus virulence markers appear to have limited impact on the phenotype of the A(H1N1pdm09 viruses when they have been introduced into mutant viruses in laboratory settings. As such, it is unclear what the evolutionary path of the pandemic virus will be, but the monitoring of any changes in the circulating viruses will remain a global public and animal health priority.Keywords: influenza, pandemic, evolution, adaptation

  7. Adaptive control strategy for ECRH negative high-voltage power supply based on CMAC neural network

    International Nuclear Information System (INIS)

    Luo Xiaoping; Du Pengying; Du Shaowu

    2011-01-01

    In order to solve the problem that the negative high-voltage power supply in an electron cyclotron resonance heating (ECRH) system can not satisfy the requirements because of the nonlinearity and sensitivity, the direct inverse model control strategy was proposed by using cerebellar model articulation controller(CMAC) for better control, and experiments were carried out to study the system performances with CMAC tracing dynamic signals. The results show that this strategy is strong in self-learning and self-adaptation and easy to be realized. (authors)

  8. Adaptive radiation with regard to nutrient sequestration strategies in the carnivorous plants of the genus Nepenthes.

    Science.gov (United States)

    Pavlovič, Andrej

    2012-02-01

    Carnivorous pitcher plants of the genus Nepenthes have evolved a great diversity of pitcher morphologies. Selective pressures for maximizing nutrient uptake have driven speciation and diversification of the genus in a process known as adaptive radiation. This leads to the evolution of pitchers adapted to specific and often bizarre source of nutrients, which are not strictly animal-derived. One example is Nepenthes ampullaria with unusual growth pattern and pitcher morphology what enables the plant to capture a leaf litter from the canopy above. We showed that the plant benefits from nitrogen uptake by increased rate of photosynthesis and growth what may provide competitive advantage over others co-habiting plants. A possible impact of such specialization toward hybridization, an important mechanism in speciation, is discussed.

  9. An Image Enhancement Method Using the Quantum-Behaved Particle Swarm Optimization with an Adaptive Strategy

    Directory of Open Access Journals (Sweden)

    Xiaoping Su

    2013-01-01

    Full Text Available Image enhancement techniques are very important to image processing, which are used to improve image quality or extract the fine details in degraded images. In this paper, two novel objective functions based on the normalized incomplete Beta transform function are proposed to evaluate the effectiveness of grayscale image enhancement and color image enhancement, respectively. Using these objective functions, the parameters of transform functions are estimated by the quantum-behaved particle swarm optimization (QPSO. We also propose an improved QPSO with an adaptive parameter control strategy. The QPSO and the AQPSO algorithms, along with genetic algorithm (GA and particle swarm optimization (PSO, are tested on several benchmark grayscale and color images. The results show that the QPSO and AQPSO perform better than GA and PSO for the enhancement of these images, and the AQPSO has some advantages over QPSO due to its adaptive parameter control strategy.

  10. Adaptive evolution of the Hox gene family for development in bats and dolphins.

    Directory of Open Access Journals (Sweden)

    Lu Liang

    Full Text Available Bats and cetaceans (i.e., whales, dolphins, porpoises are two kinds of mammals with unique locomotive styles and occupy novel niches. Bats are the only mammals capable of sustained flight in the sky, while cetaceans have returned to the aquatic environment and are specialized for swimming. Associated with these novel adaptations to their environment, various development changes have occurred to their body plans and associated structures. Given the importance of Hox genes in many aspects of embryonic development, we conducted an analysis of the coding regions of all Hox gene family members from bats (represented by Pteropus vampyrus, Pteropus alecto, Myotis lucifugus and Myotis davidii and cetaceans (represented by Tursiops truncatus for adaptive evolution using the available draft genome sequences. Differences in the selective pressures acting on many Hox genes in bats and cetaceans were found compared to other mammals. Positive selection, however, was not found to act on any of the Hox genes in the common ancestor of bats and only upon Hoxb9 in cetaceans. PCR amplification data from additional bat and cetacean species, and application of the branch-site test 2, showed that the Hoxb2 gene within bats had significant evidence of positive selection. Thus, our study, with genomic and newly sequenced Hox genes, identifies two candidate Hox genes that may be closely linked with developmental changes in bats and cetaceans, such as those associated with the pancreatic, neuronal, thymus shape and forelimb. In addition, the difference in our results from the genome-wide scan and newly sequenced data reveals that great care must be taken in interpreting results from draft genome data from a limited number of species, and deep genetic sampling of a particular clade is a powerful tool for generating complementary data to address this limitation.

  11. Colloquium paper: adaptive specializations, social exchange, and the evolution of human intelligence.

    Science.gov (United States)

    Cosmides, Leda; Barrett, H Clark; Tooby, John

    2010-05-11

    Blank-slate theories of human intelligence propose that reasoning is carried out by general-purpose operations applied uniformly across contents. An evolutionary approach implies a radically different model of human intelligence. The task demands of different adaptive problems select for functionally specialized problem-solving strategies, unleashing massive increases in problem-solving power for ancestrally recurrent adaptive problems. Because exchange can evolve only if cooperators can detect cheaters, we hypothesized that the human mind would be equipped with a neurocognitive system specialized for reasoning about social exchange. Whereas humans perform poorly when asked to detect violations of most conditional rules, we predicted and found a dramatic spike in performance when the rule specifies an exchange and violations correspond to cheating. According to critics, people's uncanny accuracy at detecting violations of social exchange rules does not reflect a cheater detection mechanism, but extends instead to all rules regulating when actions are permitted (deontic conditionals). Here we report experimental tests that falsify these theories by demonstrating that deontic rules as a class do not elicit the search for violations. We show that the cheater detection system functions with pinpoint accuracy, searching for violations of social exchange rules only when these are likely to reveal the presence of someone who intends to cheat. It does not search for violations of social exchange rules when these are accidental, when they do not benefit the violator, or when the situation would make cheating difficult.

  12. Transient MutS-Based Hypermutation System for Adaptive Evolution of Lactobacillus casei to Low pH.

    Science.gov (United States)

    Overbeck, Tom J; Welker, Dennis L; Hughes, Joanne E; Steele, James L; Broadbent, Jeff R

    2017-10-15

    This study explored transient inactivation of the gene encoding the DNA mismatch repair enzyme MutS as a tool for adaptive evolution of Lactobacillus casei MutS deletion derivatives of L. casei 12A and ATCC 334 were constructed and subjected to a 100-day adaptive evolution process to increase lactic acid resistance at low pH. Wild-type parental strains were also subjected to this treatment. At the end of the process, the Δ mutS lesion was repaired in representative L. casei 12A and ATCC 334 Δ mutS mutant isolates. Growth studies in broth at pH 4.0 (titrated with lactic acid) showed that all four adapted strains grew more rapidly, to higher cell densities, and produced significantly more lactic acid than untreated wild-type cells. However, the adapted Δ mutS derivative mutants showed the greatest increases in growth and lactic acid production. Further characterization of the L. casei 12A-adapted Δ mutS derivative revealed that it had a significantly smaller cell volume, a rougher cell surface, and significantly better survival at pH 2.5 than parental L. casei 12A. Genome sequence analysis confirmed that transient mutS inactivation decreased DNA replication fidelity in both L. casei strains, and it identified genetic changes that might contribute to the lactic acid-resistant phenotypes of adapted cells. Targeted inactivation of three genes that had acquired nonsense mutations in the adapted L. casei 12A Δ mutS mutant derivative showed that NADH dehydrogenase ( ndh ), phosphate transport ATP-binding protein PstB ( pstB ), and two-component signal transduction system (TCS) quorum-sensing histidine protein kinase ( hpk ) genes act in combination to increase lactic acid resistance in L. casei 12A. IMPORTANCE Adaptive evolution has been applied to microorganisms to increase industrially desirable phenotypes, including acid resistance. We developed a method to increase the adaptability of Lactobacillus casei 12A and ATCC 334 through transient inactivation of the DNA

  13. Invasion strategies in clonal aquatic plants: are phenotypic differences caused by phenotypic plasticity or local adaptation?

    Science.gov (United States)

    Riis, Tenna; Lambertini, Carla; Olesen, Birgit; Clayton, John S.; Brix, Hans; Sorrell, Brian K.

    2010-01-01

    Background and Aims The successful spread of invasive plants in new environments is often linked to multiple introductions and a diverse gene pool that facilitates local adaptation to variable environmental conditions. For clonal plants, however, phenotypic plasticity may be equally important. Here the primary adaptive strategy in three non-native, clonally reproducing macrophytes (Egeria densa, Elodea canadensis and Lagarosiphon major) in New Zealand freshwaters were examined and an attempt was made to link observed differences in plant morphology to local variation in habitat conditions. Methods Field populations with a large phenotypic variety were sampled in a range of lakes and streams with different chemical and physical properties. The phenotypic plasticity of the species before and after cultivation was studied in a common garden growth experiment, and the genetic diversity of these same populations was also quantified. Key Results For all three species, greater variation in plant characteristics was found before they were grown in standardized conditions. Moreover, field populations displayed remarkably little genetic variation and there was little interaction between habitat conditions and plant morphological characteristics. Conclusions The results indicate that at the current stage of spread into New Zealand, the primary adaptive strategy of these three invasive macrophytes is phenotypic plasticity. However, while limited, the possibility that genetic diversity between populations may facilitate ecotypic differentiation in the future cannot be excluded. These results thus indicate that invasive clonal aquatic plants adapt to new introduced areas by phenotypic plasticity. Inorganic carbon, nitrogen and phosphorous were important in controlling plant size of E. canadensis and L. major, but no other relationships between plant characteristics and habitat conditions were apparent. This implies that within-species differences in plant size can be explained

  14. Social strategy games in communicating trade-offs between mitigation and adaptation in cities

    DEFF Research Database (Denmark)

    Juhola, Sirkku; Driscoll, Patrick Arthur; Suarez, Pablo

    2013-01-01

    and mitigation strategies and what kinds of negative and positive synergies can be identified between them. This paper explores how social games can help people to understand the trade-offs between mitigation and adaptation measures in an urban environment and examines the possibilities of using social gaming...... as a research method. Data was collected from Denmark, Finland and the US through organized gaming sessions. The conclusion of the study is that social games are a promising method to understand complex planning problems....

  15. Reconstructing the ups and downs of primate brain evolution: implications for adaptive hypotheses and Homo floresiensis

    Directory of Open Access Journals (Sweden)

    Barton Robert A

    2010-01-01

    Full Text Available Abstract Background Brain size is a key adaptive trait. It is often assumed that increasing brain size was a general evolutionary trend in primates, yet recent fossil discoveries have documented brain size decreases in some lineages, raising the question of how general a trend there was for brains to increase in mass over evolutionary time. We present the first systematic phylogenetic analysis designed to answer this question. Results We performed ancestral state reconstructions of three traits (absolute brain mass, absolute body mass, relative brain mass using 37 extant and 23 extinct primate species and three approaches to ancestral state reconstruction: parsimony, maximum likelihood and Bayesian Markov-chain Monte Carlo. Both absolute and relative brain mass generally increased over evolutionary time, but body mass did not. Nevertheless both absolute and relative brain mass decreased along several branches. Applying these results to the contentious case of Homo floresiensis, we find a number of scenarios under which the proposed evolution of Homo floresiensis' small brain appears to be consistent with patterns observed along other lineages, dependent on body mass and phylogenetic position. Conclusions Our results confirm that brain expansion began early in primate evolution and show that increases occurred in all major clades. Only in terms of an increase in absolute mass does the human lineage appear particularly striking, with both the rate of proportional change in mass and relative brain size having episodes of greater expansion elsewhere on the primate phylogeny. However, decreases in brain mass also occurred along branches in all major clades, and we conclude that, while selection has acted to enlarge primate brains, in some lineages this trend has been reversed. Further analyses of the phylogenetic position of Homo floresiensis and better body mass estimates are required to confirm the plausibility of the evolution of its small brain

  16. Gene duplication, modularity and adaptation in the evolution of the aflatoxin gene cluster

    Directory of Open Access Journals (Sweden)

    Jakobek Judy L

    2007-07-01

    Full Text Available Abstract Background The biosynthesis of aflatoxin (AF involves over 20 enzymatic reactions in a complex polyketide pathway that converts acetate and malonate to the intermediates sterigmatocystin (ST and O-methylsterigmatocystin (OMST, the respective penultimate and ultimate precursors of AF. Although these precursors are chemically and structurally very similar, their accumulation differs at the species level for Aspergilli. Notable examples are A. nidulans that synthesizes only ST, A. flavus that makes predominantly AF, and A. parasiticus that generally produces either AF or OMST. Whether these differences are important in the evolutionary/ecological processes of species adaptation and diversification is unknown. Equally unknown are the specific genomic mechanisms responsible for ordering and clustering of genes in the AF pathway of Aspergillus. Results To elucidate the mechanisms that have driven formation of these clusters, we performed systematic searches of aflatoxin cluster homologs across five Aspergillus genomes. We found a high level of gene duplication and identified seven modules consisting of highly correlated gene pairs (aflA/aflB, aflR/aflS, aflX/aflY, aflF/aflE, aflT/aflQ, aflC/aflW, and aflG/aflL. With the exception of A. nomius, contrasts of mean Ka/Ks values across all cluster genes showed significant differences in selective pressure between section Flavi and non-section Flavi species. A. nomius mean Ka/Ks values were more similar to partial clusters in A. fumigatus and A. terreus. Overall, mean Ka/Ks values were significantly higher for section Flavi than for non-section Flavi species. Conclusion Our results implicate several genomic mechanisms in the evolution of ST, OMST and AF cluster genes. Gene modules may arise from duplications of a single gene, whereby the function of the pre-duplication gene is retained in the copy (aflF/aflE or the copies may partition the ancestral function (aflA/aflB. In some gene modules, the

  17. Computational Strategies for Dissecting the High-Dimensional Complexity of Adaptive Immune Repertoires

    Directory of Open Access Journals (Sweden)

    Enkelejda Miho

    2018-02-01

    Full Text Available The adaptive immune system recognizes antigens via an immense array of antigen-binding antibodies and T-cell receptors, the immune repertoire. The interrogation of immune repertoires is of high relevance for understanding the adaptive immune response in disease and infection (e.g., autoimmunity, cancer, HIV. Adaptive immune receptor repertoire sequencing (AIRR-seq has driven the quantitative and molecular-level profiling of immune repertoires, thereby revealing the high-dimensional complexity of the immune receptor sequence landscape. Several methods for the computational and statistical analysis of large-scale AIRR-seq data have been developed to resolve immune repertoire complexity and to understand the dynamics of adaptive immunity. Here, we review the current research on (i diversity, (ii clustering and network, (iii phylogenetic, and (iv machine learning methods applied to dissect, quantify, and compare the architecture, evolution, and specificity of immune repertoires. We summarize outstanding questions in computational immunology and propose future directions for systems immunology toward coupling AIRR-seq with the computational discovery of immunotherapeutics, vaccines, and immunodiagnostics.

  18. An adaptive deep Q-learning strategy for handwritten digit recognition.

    Science.gov (United States)

    Qiao, Junfei; Wang, Gongming; Li, Wenjing; Chen, Min

    2018-02-22

    Handwritten digits recognition is a challenging problem in recent years. Although many deep learning-based classification algorithms are studied for handwritten digits recognition, the recognition accuracy and running time still need to be further improved. In this paper, an adaptive deep Q-learning strategy is proposed to improve accuracy and shorten running time for handwritten digit recognition. The adaptive deep Q-learning strategy combines the feature-extracting capability of deep learning and the decision-making of reinforcement learning to form an adaptive Q-learning deep belief network (Q-ADBN). First, Q-ADBN extracts the features of original images using an adaptive deep auto-encoder (ADAE), and the extracted features are considered as the current states of Q-learning algorithm. Second, Q-ADBN receives Q-function (reward signal) during recognition of the current states, and the final handwritten digits recognition is implemented by maximizing the Q-function using Q-learning algorithm. Finally, experimental results from the well-known MNIST dataset show that the proposed Q-ADBN has a superiority to other similar methods in terms of accuracy and running time. Copyright © 2018 Elsevier Ltd. All rights reserved.

  19. Adaptive evolution influences the infectious dose of MERS-CoV necessary to achieve severe respiratory disease.

    Science.gov (United States)

    Douglas, Madeline G; Kocher, Jacob F; Scobey, Trevor; Baric, Ralph S; Cockrell, Adam S

    2018-04-01

    We recently established a mouse model (288-330 +/+ ) that developed acute respiratory disease resembling human pathology following infection with a high dose (5 × 10 6 PFU) of mouse-adapted MERS-CoV (icMERSma1). Although this high dose conferred fatal respiratory disease in mice, achieving similar pathology at lower viral doses may more closely reflect naturally acquired infections. Through continued adaptive evolution of icMERSma1 we generated a novel mouse-adapted MERS-CoV (maM35c4) capable of achieving severe respiratory disease at doses between 10 3 and 10 5 PFU. Novel mutations were identified in the maM35c4 genome that may be responsible for eliciting etiologies of acute respiratory distress syndrome at 10-1000 fold lower viral doses. Importantly, comparative genetics of the two mouse-adapted MERS strains allowed us to identify specific mutations that remained fixed through an additional 20 cycles of adaptive evolution. Our data indicate that the extent of MERS-CoV adaptation determines the minimal infectious dose required to achieve severe respiratory disease. Copyright © 2017 Elsevier Inc. All rights reserved.

  20. Adaptive landscape and functional diversity of Neotropical cichlids: implications for the ecology and evolution of Cichlinae (Cichlidae; Cichliformes).

    Science.gov (United States)

    Arbour, J H; López-Fernández, H

    2014-11-01

    Morphological, lineage and ecological diversity can vary substantially even among closely related lineages. Factors that influence morphological diversification, especially in functionally relevant traits, can help to explain the modern distribution of disparity across phylogenies and communities. Multivariate axes of feeding functional morphology from 75 species of Neotropical cichlid and a stepwise-AIC algorithm were used to estimate the adaptive landscape of functional morphospace in Cichlinae. Adaptive landscape complexity and convergence, as well as the functional diversity of Cichlinae, were compared with expectations under null evolutionary models. Neotropical cichlid feeding function varied primarily between traits associated with ram feeding vs. suction feeding/biting and secondarily with oral jaw muscle size and pharyngeal crushing capacity. The number of changes in selective regimes and the amount of convergence between lineages was higher than expected under a null model of evolution, but convergence was not higher than expected under a similarly complex adaptive landscape. Functional disparity was compatible with an adaptive landscape model, whereas the distribution of evolutionary change through morphospace corresponded with a process of evolution towards a single adaptive peak. The continentally distributed Neotropical cichlids have evolved relatively rapidly towards a number of adaptive peaks in functional trait space. Selection in Cichlinae functional morphospace is more complex than expected under null evolutionary models. The complexity of selective constraints in feeding morphology has likely been a significant contributor to the diversity of feeding ecology in this clade. © 2014 European Society For Evolutionary Biology. Journal of Evolutionary Biology © 2014 European Society For Evolutionary Biology.

  1. New adaptive differencing strategy in the PENTRAN 3-d parallel Sn code

    International Nuclear Information System (INIS)

    Sjoden, G.E.; Haghighat, A.

    1996-01-01

    It is known that three-dimensional (3-D) discrete ordinates (S n ) transport problems require an immense amount of storage and computational effort to solve. For this reason, parallel codes that offer a capability to completely decompose the angular, energy, and spatial domains among a distributed network of processors are required. One such code recently developed is PENTRAN, which iteratively solves 3-D multi-group, anisotropic S n problems on distributed-memory platforms, such as the IBM-SP2. Because large problems typically contain several different material zones with various properties, available differencing schemes should automatically adapt to the transport physics in each material zone. To minimize the memory and message-passing overhead required for massively parallel S n applications, available differencing schemes in an adaptive strategy should also offer reasonable accuracy and positivity, yet require only the zeroth spatial moment of the transport equation; differencing schemes based on higher spatial moments, in spite of their greater accuracy, require at least twice the amount of storage and communication cost for implementation in a massively parallel transport code. This paper discusses a new adaptive differencing strategy that uses increasingly accurate schemes with low parallel memory and communication overhead. This strategy, implemented in PENTRAN, includes a new scheme, exponential directional averaged (EDA) differencing

  2. Implementing the Integrated Strategy for the Cultural Adaptation of Evidence-Based Interventions: An Illustration.

    Science.gov (United States)

    Sidani, Souraya; Ibrahim, Sarah; Lok, Jana; Fan, Lifeng; Fox, Mary

    2018-01-01

    Background Persons' cultural beliefs about a health problem can affect their perceived acceptability of evidence-based interventions, undermining evidence-based interventions' adherence, and uptake to manage the problem. Cultural adaptation has the potential to enhance the acceptability, uptake, and adherence to evidence-based interventions. Purpose To illustrate the implementation of the first two phases of the integrated strategy for cultural adaptation by examining Chinese Canadians' perceptions of chronic insomnia and evidence-based behavioral therapies for insomnia. Methods Chinese Canadians ( n = 14) with chronic insomnia attended a group session during which they completed established instruments measuring beliefs about sleep and insomnia, and their perceptions of factors that contribute to chronic insomnia. Participants rated the acceptability of evidence-based behavioral therapies and discussed their cultural perspectives regarding chronic insomnia and its treatment. Results Participants actively engaged in the activities planned for the first two phases of the integrated strategy and identified the most significant factor contributing to chronic insomnia and the evidence-based intervention most acceptable for their cultural group. Conclusions The protocol for implementing the two phases of the integrated strategy for cultural adaptation of evidence-based interventions was feasible, acceptable, and useful in identifying culturally relevant evidence-based interventions.

  3. Adaptive simplification and the evolution of gecko locomotion: Morphological and biomechanical consequences of losing adhesion

    Science.gov (United States)

    Higham, Timothy E.; Birn-Jeffery, Aleksandra V.; Collins, Clint E.; Hulsey, C. Darrin; Russell, Anthony P.

    2015-01-01

    Innovations permit the diversification of lineages, but they may also impose functional constraints on behaviors such as locomotion. Thus, it is not surprising that secondary simplification of novel locomotory traits has occurred several times among vertebrates and could potentially lead to exceptional divergence when constraints are relaxed. For example, the gecko adhesive system is a remarkable innovation that permits locomotion on surfaces unavailable to other animals, but has been lost or simplified in species that have reverted to a terrestrial lifestyle. We examined the functional and morphological consequences of this adaptive simplification in the Pachydactylus radiation of geckos, which exhibits multiple unambiguous losses or bouts of simplification of the adhesive system. We found that the rates of morphological and 3D locomotor kinematic evolution are elevated in those species that have simplified or lost adhesive capabilities. This finding suggests that the constraints associated with adhesion have been circumvented, permitting these species to either run faster or burrow. The association between a terrestrial lifestyle and the loss/reduction of adhesion suggests a direct link between morphology, biomechanics, and ecology. PMID:25548182

  4. Adaptive evolution of threonine deaminase in plant defense against insect herbivores

    Energy Technology Data Exchange (ETDEWEB)

    Gonzales-Vigil, Eliana; Bianchetti, Christopher M.; Phillips, Jr., George N.; Howe, Gregg A. (MSU); (UW)

    2011-11-07

    Gene duplication is a major source of plant chemical diversity that mediates plant-herbivore interactions. There is little direct evidence, however, that novel chemical traits arising from gene duplication reduce herbivory. Higher plants use threonine deaminase (TD) to catalyze the dehydration of threonine (Thr) to {alpha}-ketobutyrate and ammonia as the committed step in the biosynthesis of isoleucine (Ile). Cultivated tomato and related Solanum species contain a duplicated TD paralog (TD2) that is coexpressed with a suite of genes involved in herbivore resistance. Analysis of TD2-deficient tomato lines showed that TD2 has a defensive function related to Thr catabolism in the gut of lepidopteran herbivores. During herbivory, the regulatory domain of TD2 is removed by proteolysis to generate a truncated protein (pTD2) that efficiently degrades Thr without being inhibited by Ile. We show that this proteolytic activation step occurs in the gut of lepidopteran but not coleopteran herbivores, and is catalyzed by a chymotrypsin-like protease of insect origin. Analysis of purified recombinant enzymes showed that TD2 is remarkably more resistant to proteolysis and high temperature than the ancestral TD1 isoform. The crystal structure of pTD2 provided evidence that electrostatic interactions constitute a stabilizing feature associated with adaptation of TD2 to the extreme environment of the lepidopteran gut. These findings demonstrate a role for gene duplication in the evolution of a plant defense that targets and co-opts herbivore digestive physiology.

  5. Towards Adaptive Management: Examining the Strategies of Policy Entrepreneurs in Dutch Water Management

    Directory of Open Access Journals (Sweden)

    Stijn Brouwer

    2011-12-01

    Full Text Available The growing awareness of the complexities and uncertainties in water management has put into question the existing paradigms in this field. Increasingly more flexible, integrated, and adaptive policies are promoted. In this context, the understanding of how to effect policy change is becoming more important. This article analyzes policy making at the micro level, focusing on the behavior of policy entrepreneurs, which we understand here as risk-taking bureaucrats who seek to change policy and are involved throughout the policy-change process. Policy entrepreneurs have received a certain level of attention in the adaptive co-management literature and the policy sciences in past decades. Yet, the understanding of the actions they can take to facilitate policy change remains limited. This study addresses this gap in focusing on the strategies that policy entrepreneurs employ in their efforts to effect policy change. The article draws on both theoretical exploration and in-depth field research on water management in the Netherlands, which included a series of semi-structured interviews and a focus group with policy entrepreneurs. We conclude that policy entrepreneurs employ four types of strategies: (1 attention and support-seeking strategies, to demonstrate the significance of a problem and to convince a wide range of participants about their preferred policy; (2 linking strategies, to link with other parties, projects, ideas, and policy games; (3 relational management strategies, to manage the relational factor in policy-change trajectories; and finally, (4 arena strategies, to influence the time and place wherein decisions are made. Our study suggests that by employing these strategies when the "time is right," the development of policy streams and consequently their coupling can, to some extent, be influenced and steered. In other words, policy entrepreneurs can, to a degree, prepare for a window of opportunity and hence direct policy change.

  6. Climate change and eHealth: a promising strategy for health sector mitigation and adaptation

    Directory of Open Access Journals (Sweden)

    Åsa Holmner

    2012-06-01

    Full Text Available Climate change is one of today's most pressing global issues. Policies to guide mitigation and adaptation are needed to avoid the devastating impacts of climate change. The health sector is a significant contributor to greenhouse gas emissions in developed countries, and its climate impact in low-income countries is growing steadily. This paper reviews and discusses the literature regarding health sector mitigation potential, known and hypothetical co-benefits, and the potential of health information technology, such as eHealth, in climate change mitigation and adaptation. The promising role of eHealth as an adaptation strategy to reduce societal vulnerability to climate change, and the link's between mitigation and adaptation, are also discussed. The topic of environmental eHealth has gained little attention to date, despite its potential to contribute to more sustainable and green health care. A growing number of local and global initiatives on ‘green information and communication technology (ICT’ are now mentioning eHealth as a promising technology with the potential to reduce emission rates from ICT use. However, the embracing of eHealth is slow because of limitations in technological infrastructure, capacity and political will. Further research on potential emissions reductions and co-benefits with green ICT, in terms of health outcomes and economic effectiveness, would be valuable to guide development and implementation of eHealth in health sector mitigation and adaptation policies.

  7. Climate change and eHealth: a promising strategy for health sector mitigation and adaptation

    Science.gov (United States)

    Holmner, Åsa; Rocklöv, Joacim; Ng, Nawi; Nilsson, Maria

    2012-01-01

    Climate change is one of today's most pressing global issues. Policies to guide mitigation and adaptation are needed to avoid the devastating impacts of climate change. The health sector is a significant contributor to greenhouse gas emissions in developed countries, and its climate impact in low-income countries is growing steadily. This paper reviews and discusses the literature regarding health sector mitigation potential, known and hypothetical co-benefits, and the potential of health information technology, such as eHealth, in climate change mitigation and adaptation. The promising role of eHealth as an adaptation strategy to reduce societal vulnerability to climate change, and the link's between mitigation and adaptation, are also discussed. The topic of environmental eHealth has gained little attention to date, despite its potential to contribute to more sustainable and green health care. A growing number of local and global initiatives on ‘green information and communication technology (ICT)’ are now mentioning eHealth as a promising technology with the potential to reduce emission rates from ICT use. However, the embracing of eHealth is slow because of limitations in technological infrastructure, capacity and political will. Further research on potential emissions reductions and co-benefits with green ICT, in terms of health outcomes and economic effectiveness, would be valuable to guide development and implementation of eHealth in health sector mitigation and adaptation policies. PMID:22679398

  8. Evolution of static allometries: adaptive change in allometric slopes of eye span in stalk-eyed flies.

    Science.gov (United States)

    Voje, Kjetil L; Hansen, Thomas F

    2013-02-01

    Julian Huxley showed that within-species (static) allometric (power-law) relations can arise from proportional growth regulation with the exponent in the power law equaling the factor of proportionality. Allometric exponents may therefore be hard to change and act as constraints on the independent evolution of traits. In apparent contradiction to this, many empirical studies have concluded that static allometries are evolvable. Many of these studies have been based, however, on a broad definition of allometry that includes any monotonic shape change with size, and do not falsify the hypothesis of constrained narrow-sense allometry. Here, we present the first phylogenetic comparative study of narrow-sense allometric exponents based on a reanalysis of data on eye span and body size in stalk-eyed flies (Diopsidae). Consistent with a role in sexual selection, we found strong evidence that male slopes were tracking "optima" based on sexual dimorphism and relative male trait size. This tracking was slow, however, with estimated times of 2-3 million years for adaptation to exceed ancestral influence on the trait. Our results are therefore consistent with adaptive evolution on million-year time scales, but cannot rule out that static allometry may act as a constraint on eye-span adaptation at shorter time scales. © 2012 The Author(s). Evolution© 2012 The Society for the Study of Evolution.

  9. Adaptive evolution of a key gene affecting queen and worker traits in the honey bee, Apis mellifera.

    Science.gov (United States)

    Kent, Clement F; Issa, Amer; Bunting, Alexandra C; Zayed, Amro

    2011-12-01

    The vitellogenin egg yolk precursor protein represents a well-studied case of social pleiotropy in the model organism Apis mellifera. Vitellogenin is associated with fecundity in queens and plays a major role in controlling division of labour in workers, thereby affecting both individual and colony-level fitness. We studied the molecular evolution of vitellogenin and seven other genes sequenced in a large population panel of Apis mellifera and several closely related species to investigate the role of social pleiotropy on adaptive protein evolution. We found a significant excess of nonsynonymous fixed differences between A. mellifera, A. cerana and A. florea relative to synonymous sites indicating high rates of adaptive evolution at vitellogenin. Indeed, 88% of amino acid changes were fixed by selection in some portions of the gene. Further, vitellogenin exhibited hallmark signatures of selective sweeps in A. mellifera, including a significant skew in the allele frequency spectrum, extreme levels of genetic differentiation and linkage disequilibrium. Finally, replacement polymorphisms in vitellogenin were significantly enriched in parts of the protein involved in binding lipid, establishing a link between the gene's structure, function and effects on fitness. Our case study provides unequivocal evidence of historical and ongoing bouts of adaptive evolution acting on a key socially pleiotropic gene in the honey bee. © 2011 Blackwell Publishing Ltd.

  10. Livestock in a changing climate: production system transitions as an adaptation strategy for agriculture

    International Nuclear Information System (INIS)

    Weindl, Isabelle; Lotze-Campen, Hermann; Popp, Alexander; Müller, Christoph; Schmitz, Christoph; Rolinski, Susanne; Havlík, Petr; Herrero, Mario

    2015-01-01

    Livestock farming is the world’s largest land use sector and utilizes around 60% of the global biomass harvest. Over the coming decades, climate change will affect the natural resource base of livestock production, especially the productivity of rangeland and feed crops. Based on a comprehensive impact modeling chain, we assess implications of different climate projections for agricultural production costs and land use change and explore the effectiveness of livestock system transitions as an adaptation strategy. Simulated climate impacts on crop yields and rangeland productivity generate adaptation costs amounting to 3% of total agricultural production costs in 2045 (i.e. 145 billion US$). Shifts in livestock production towards mixed crop-livestock systems represent a resource- and cost-efficient adaptation option, reducing agricultural adaptation costs to 0.3% of total production costs and simultaneously abating deforestation by about 76 million ha globally. The relatively positive climate impacts on grass yields compared with crop yields favor grazing systems inter alia in South Asia and North America. Incomplete transitions in production systems already have a strong adaptive and cost reducing effect: a 50% shift to mixed systems lowers agricultural adaptation costs to 0.8%. General responses of production costs to system transitions are robust across different global climate and crop models as well as regarding assumptions on CO 2 fertilization, but simulated values show a large variation. In the face of these uncertainties, public policy support for transforming livestock production systems provides an important lever to improve agricultural resource management and lower adaptation costs, possibly even contributing to emission reduction. (letter)

  11. Evolution of learning strategies in temporally and spatially variable environments: a review of theory.

    Science.gov (United States)

    Aoki, Kenichi; Feldman, Marcus W

    2014-02-01

    The theoretical literature from 1985 to the present on the evolution of learning strategies in variable environments is reviewed, with the focus on deterministic dynamical models that are amenable to local stability analysis, and on deterministic models yielding evolutionarily stable strategies. Individual learning, unbiased and biased social learning, mixed learning, and learning schedules are considered. A rapidly changing environment or frequent migration in a spatially heterogeneous environment favors individual learning over unbiased social learning. However, results are not so straightforward in the context of learning schedules or when biases in social learning are introduced. The three major methods of modeling temporal environmental change--coevolutionary, two-timescale, and information decay--are compared and shown to sometimes yield contradictory results. The so-called Rogers' paradox is inherent in the two-timescale method as originally applied to the evolution of pure strategies, but is often eliminated when the other methods are used. Moreover, Rogers' paradox is not observed for the mixed learning strategies and learning schedules that we review. We believe that further theoretical work is necessary on learning schedules and biased social learning, based on models that are logically consistent and empirically pertinent. Copyright © 2013 Elsevier Inc. All rights reserved.

  12. Evolution of learning strategies in temporally and spatially variable environments: A review of theory

    Science.gov (United States)

    Aoki, Kenichi; Feldman, Marcus W.

    2013-01-01

    The theoretical literature from 1985 to the present on the evolution of learning strategies in variable environments is reviewed, with the focus on deterministic dynamical models that are amenable to local stability analysis, and on deterministic models yielding evolutionarily stable strategies. Individual learning, unbiased and biased social learning, mixed learning, and learning schedules are considered. A rapidly changing environment or frequent migration in a spatially heterogeneous environment favors individual learning over unbiased social learning. However, results are not so straightforward in the context of learning schedules or when biases in social learning are introduced. The three major methods of modeling temporal environmental change – coevolutionary, two-timescale, and information decay – are compared and shown to sometimes yield contradictory results. The so-called Rogers’ paradox is inherent in the two-timescale method as originally applied to the evolution of pure strategies, but is often eliminated when the other methods are used. Moreover, Rogers’ paradox is not observed for the mixed learning strategies and learning schedules that we review. We believe that further theoretical work is necessary on learning schedules and biased social learning, based on models that are logically consistent and empirically pertinent. PMID:24211681

  13. Strategy evolution driven by switching probabilities in structured multi-agent systems

    Science.gov (United States)

    Zhang, Jianlei; Chen, Zengqiang; Li, Zhiqi

    2017-10-01

    Evolutionary mechanism driving the commonly seen cooperation among unrelated individuals is puzzling. Related models for evolutionary games on graphs traditionally assume that players imitate their successful neighbours with higher benefits. Notably, an implicit assumption here is that players are always able to acquire the required pay-off information. To relax this restrictive assumption, a contact-based model has been proposed, where switching probabilities between strategies drive the strategy evolution. However, the explicit and quantified relation between a player's switching probability for her strategies and the number of her neighbours remains unknown. This is especially a key point in heterogeneously structured system, where players may differ in the numbers of their neighbours. Focusing on this, here we present an augmented model by introducing an attenuation coefficient and evaluate its influence on the evolution dynamics. Results show that the individual influence on others is negatively correlated with the contact numbers specified by the network topologies. Results further provide the conditions under which the coexisting strategies can be calculated analytically.

  14. Adaptation and convergent evolution within the Jamesonia-Eriosorus complex in high-elevation biodiverse Andean hotspots.

    Science.gov (United States)

    Sánchez-Baracaldo, Patricia; Thomas, Gavin H

    2014-01-01

    The recent uplift of the tropical Andes (since the late Pliocene or early Pleistocene) provided extensive ecological opportunity for evolutionary radiations. We test for phylogenetic and morphological evidence of adaptive radiation and convergent evolution to novel habitats (exposed, high-altitude páramo habitats) in the Andean fern genera Jamesonia and Eriosorus. We construct time-calibrated phylogenies for the Jamesonia-Eriosorus clade. We then use recent phylogenetic comparative methods to test for evolutionary transitions among habitats, associations between habitat and leaf morphology, and ecologically driven variation in the rate of morphological evolution. Páramo species (Jamesonia) display morphological adaptations consistent with convergent evolution in response to the demands of a highly exposed environment but these adaptations are associated with microhabitat use rather than the páramo per se. Species that are associated with exposed microhabitats (including Jamesonia and Eriorsorus) are characterized by many but short pinnae per frond whereas species occupying sheltered microhabitats (primarily Eriosorus) have few but long pinnae per frond. Pinnae length declines more rapidly with altitude in sheltered species. Rates of speciation are significantly higher among páramo than non-páramo lineages supporting the hypothesis of adaptation and divergence in the unique Páramo biodiversity hotspot.

  15. Shared human-chimpanzee pattern of perinatal femoral shaft morphology and its implications for the evolution of hominin locomotor adaptations.

    Directory of Open Access Journals (Sweden)

    Naoki Morimoto

    Full Text Available Acquisition of bipedality is a hallmark of human evolution. How bipedality evolved from great ape-like locomotor behaviors, however, is still highly debated. This is mainly because it is difficult to infer locomotor function, and even more so locomotor kinematics, from fossil hominin long bones. Structure-function relationships are complex, as long bone morphology reflects phyletic history, developmental programs, and loading history during an individual's lifetime. Here we discriminate between these factors by investigating the morphology of long bones in fetal and neonate great apes and humans, before the onset of locomotion.Comparative morphometric analysis of the femoral diaphysis indicates that its morphology reflects phyletic relationships between hominoid taxa to a greater extent than taxon-specific locomotor adaptations. Diaphyseal morphology in humans and chimpanzees exhibits several shared-derived features, despite substantial differences in locomotor adaptations. Orangutan and gorilla morphologies are largely similar, and likely represent the primitive hominoid state.These findings are compatible with two possible evolutionary scenarios. Diaphyseal morphology may reflect retained adaptive traits of ancestral taxa, hence human-chimpanzee shared-derived features may be indicative of the locomotor behavior of our last common ancestor. Alternatively, diaphyseal morphology might reflect evolution by genetic drift (neutral evolution rather than selection, and might thus be more informative about phyletic relationships between taxa than about locomotor adaptations. Both scenarios are consistent with the hypothesis that knuckle-walking in chimpanzees and gorillas resulted from convergent evolution, and that the evolution of human bipedality is unrelated to extant great ape locomotor specializations.

  16. The Evolution of Diapsid Reproductive Strategy with Inferences about Extinct Taxa.

    Directory of Open Access Journals (Sweden)

    Jason R Moore

    Full Text Available Diapsids show an extremely wide range of reproductive strategies. Offspring may receive no parental care, care from only one sex, care from both parents, or care under more complex regimes. Young may vary from independent, super-precocial hatchlings to altricial neonates needing much care before leaving the nest. Parents can invest heavily in a few young, or less so in a larger number. Here we examine the evolution of these traits across a composite phylogeny spanning the extant diapsids and including the limited number of extinct taxa for which reproductive strategies can be well constrained. Generalized estimating equation(GEE-based phylogenetic comparative methods demonstrate the influences of body mass, parental care strategy and hatchling maturity on clutch volume across the diapsids. The influence of polygamous reproduction is not important despite a large sample size. Applying the results of these models to the dinosaurs supports the hypothesis of paternal care (male only in derived non-avian theropods, previously suggested based on simpler analyses. These data also suggest that sauropodomorphs did not care for their young. The evolution of parental-care occurs in an almost linear series of transitions. Paternal care rarely gives rise to other care strategies. Where hatchling condition changes, diapsids show an almost unidirectional tendency of evolution towards increased altriciality. Transitions to social monogamy from the ancestral state in diapsids, where both sexes are polygamous, are common. In contrast, once evolved, polygyny and polyandry are very evolutionarily stable. Polygyny and maternal care correlate, as do polyandry and paternal care. Ancestral-character estimation (ACE of these care strategies with the character transition likelihoods estimated from the original data gives good confidence at most important nodes. These analyses suggest that the basalmost diapsids had no parental care. Crocodilians independently evolved

  17. Research of Ant Colony Optimized Adaptive Control Strategy for Hybrid Electric Vehicle

    Directory of Open Access Journals (Sweden)

    Linhui Li

    2014-01-01

    Full Text Available Energy management control strategy of hybrid electric vehicle has a great influence on the vehicle fuel consumption with electric motors adding to the traditional vehicle power system. As vehicle real driving cycles seem to be uncertain, the dynamic driving cycles will have an impact on control strategy’s energy-saving effect. In order to better adapt the dynamic driving cycles, control strategy should have the ability to recognize the real-time driving cycle and adaptively adjust to the corresponding off-line optimal control parameters. In this paper, four types of representative driving cycles are constructed based on the actual vehicle operating data, and a fuzzy driving cycle recognition algorithm is proposed for online recognizing the type of actual driving cycle. Then, based on the equivalent fuel consumption minimization strategy, an ant colony optimization algorithm is utilized to search the optimal control parameters “charge and discharge equivalent factors” for each type of representative driving cycle. At last, the simulation experiments are conducted to verify the accuracy of the proposed fuzzy recognition algorithm and the validity of the designed control strategy optimization method.

  18. Co-Evolution of Opinion and Strategy in Persuasion Dynamics:. AN Evolutionary Game Theoretical Approach

    Science.gov (United States)

    Ding, Fei; Liu, Yun; Li, Yong

    In this paper, a new model of opinion formation within the framework of evolutionary game theory is presented. The model simulates strategic situations when people are in opinion discussion. Heterogeneous agents adjust their behaviors to the environment during discussions, and their interacting strategies evolve together with opinions. In the proposed game, we take into account payoff discount to join a discussion, and the situation that people might drop out of an unpromising game. Analytical and emulational results show that evolution of opinion and strategy always tend to converge, with utility threshold, memory length, and decision uncertainty parameters influencing the convergence time. The model displays different dynamical regimes when we set differently the rule when people are at a loss in strategy.

  19. The selection and adaptation of staff as the basis of the successful implementation of HR strategy

    Directory of Open Access Journals (Sweden)

    Vanicheva A.G.

    2016-11-01

    Full Text Available the article deals with questions of effective strategies of HR policy in the field of selection and adaptation of staff in the company. The text gives an information about effective methods of selection and adaptation, also it draws our attention to development of communication between employees. This paper can help to pay managers’ attention to effective selection and adaptation taking into consideration that introduction of a new employee to a position is responsible enough. Probably, first days in a new company are crucial for the system of motivation of HR policy in the development of HR strategy. Much attention is given to stages of adaptation for employee or chief executive.

  20. Traffic-Adaptive Proactive Sp ectrum Handoff Strategy for Graded Secondary Users in Cognitive Radio Networks

    Institute of Scientific and Technical Information of China (English)

    ZHANG Lei; SONG Tiecheng; WU Ming; BAO Xu; GUO Jie; HU Jing

    2015-01-01

    In order to meet diff erent delay require-ments of various communication services in Cognitive ra-dio (CR) networks, Secondary users (SUs) are divided into two classes according to the priority of accessing to spec-trum in this paper. Based on the proactive spectrum hand-off scheme, the Preemptive resume priority (PRP) M/G/1 queueing is used to characterize multiple spectrum hand-off s under two diff erent spectrum handoff strategies. The traffic-adaptive spectrum handoff strategy is proposed for graded SUs so as to minimize the average cumulative hand-off delay. Simulation results not only verify that our theo-retical analysis is valid, but also show that the strategy we proposed can reduce the average cumulative handoff delay evidently. The eff ect of service rate on the proposed spec-trum switching point and the admissible access region are provided.

  1. Climate change in semi-arid Malawi: Perceptions, adaptation strategies and water governance

    Directory of Open Access Journals (Sweden)

    Miriam K. Joshua

    2016-04-01

    Full Text Available Climate change and variability are a threat to sustainable agricultural production in semi-arid areas of Malawi. Overdependence on subsistence rain-fed agriculture in these areas calls for the identification of sustainable adaptation strategies. A study was therefore conducted in Chikwawa, a semi-arid district in southern Malawi, to: (1 assess community’s perception of a changing climate against empirical evidence, (2 determine their local adaptive measures, (3 evaluate the potential of irrigated agriculture as an adaptive measure in household food security and (4 challenges over access to available water resources. The study employed focus group discussions and key informant interviews to assess people’s perceptions of climate change and variability and their desired interventions. To validate the people’s perceptions, rainfall and temperature data for the period 1960–2010 were analysed. A participatory complete randomised experimental design in both rain-fed and dry season–irrigated conditions was conducted to assess a maize cropping system that would improve adaptation. The study established persistent declining yields from rain-fed production in part because of perennial rainfall failure. In response, the community has shifted its focus to irrigation as an adaptation strategy, which has in turn triggered water conflicts in the community over the control of the resource. Water legislation however fails to adequately provide for rules governing sharing of water resources between various stakeholders. This article therefore recommends development of an appropriate institutional framework that forms a strong basis for equitable distribution of water for irrigation in areas most vulnerable to extreme climate events – including droughts and floods. Keywords: Food Security; Climate Change and Variability; Rainfall Variability; Irrigation; Water Resources; Governance Crisis

  2. Testing for adaptive evolution of the female reproductive protein ZPC in mammals, birds and fishes reveals problems with the M7-M8 likelihood ratio test.

    Science.gov (United States)

    Berlin, Sofia; Smith, Nick G C

    2005-11-10

    Adaptive evolution appears to be a common feature of reproductive proteins across a very wide range of organisms. A promising way of addressing the evolutionary forces responsible for this general phenomenon is to test for adaptive evolution in the same gene but among groups of species, which differ in their reproductive biology. One can then test evolutionary hypotheses by asking whether the variation in adaptive evolution is consistent with the variation in reproductive biology. We have attempted to apply this approach to the study of a female reproductive protein, zona pellucida C (ZPC), which has been previously shown by the use of likelihood ratio tests (LRTs) to be under positive selection in mammals. We tested for evidence of adaptive evolution of ZPC in 15 mammalian species, in 11 avian species and in six fish species using three different LRTs (M1a-M2a, M7-M8, and M8a-M8). The only significant findings of adaptive evolution came from the M7-M8 test in mammals and fishes. Since LRTs of adaptive evolution may yield false positives in some situations, we examined the properties of the LRTs by several different simulation methods. When we simulated data to test the robustness of the LRTs, we found that the pattern of evolution in ZPC generates an excess of false positives for the M7-M8 LRT but not for the M1a-M2a or M8a-M8 LRTs. This bias is strong enough to have generated the significant M7-M8 results for mammals and fishes. We conclude that there is no strong evidence for adaptive evolution of ZPC in any of the vertebrate groups we studied, and that the M7-M8 LRT can be biased towards false inference of adaptive evolution by certain patterns of non-adaptive evolution.

  3. Comparison of Strategies for Climate Change Adaptation of Water Supply and Flood Control Reservoirs

    Science.gov (United States)

    Ng, T. L.; Yang, P.; Bhushan, R.

    2016-12-01

    With climate change, streamflows are expected to become more fluctuating, with more frequent and intense floods and droughts. This complicates reservoir operation, which is highly sensitive to inflow variability. We make a comparative evaluation of three strategies for adapting reservoirs to climate-induced shifts in streamflow patterns. Specifically, we examine the effectiveness of (i) expanding the capacities of reservoirs by way of new off-stream reservoirs, (ii) introducing wastewater reclamation to augment supplies, and (iii) improving real-time streamflow forecasts for more optimal decision-making. The first two are hard strategies involving major infrastructure modifications, while the third a soft strategy entailing adjusting the system operation. A comprehensive side-by-side comparison of the three strategies is as yet lacking in the literature despite the many past studies investigating the strategies individually. To this end, we developed an adaptive forward-looking linear program that solves to yield the optimal decisions for the current time as a function of an ensemble forecast of future streamflows. Solving the model repeatedly on a rolling basis with regular updating of the streamflow forecast simulates the system behavior over the entire operating horizon. Results are generated for two hypothetical water supply and flood control reservoirs of differing inflows and demands. Preliminary findings suggest that of the three strategies, improving streamflow forecasts to be most effective in mitigating the effects of climate change. We also found that, in average terms, both additional reservoir capacity and wastewater reclamation have potential to reduce water shortage and downstream flooding. However, in the worst case, the potential of the former to reduce water shortage is limited, and similarly so the potential of the latter to reduce downstream flooding.

  4. Adaptive and Qualitative Changes in Encoding Strategy With Experience: Evidence From the Test-Expectancy Paradigm

    Science.gov (United States)

    Finley, Jason R.; Benjamin, Aaron S.

    2012-01-01

    Three experiments demonstrated learners’ abilities to adaptively and qualitatively accommodate their encoding strategies to the demands of an upcoming test. Stimuli were word pairs. In Experiment 1, test expectancy was induced for either cued recall (of targets given cues) or free recall (of targets only) across 4 study–test cycles of the same test format, followed by a final critical cycle featuring either the expected or the unexpected test format. For final tests of both cued and free recall, participants who had expected that test format outperformed those who had not. This disordinal interaction, supported by recognition and self-report data, demonstrated not mere differences in effort based on anticipated test difficulty, but rather qualitative and appropriate differences in encoding strategies based on expected task demands. Participants also came to appropriately modulate metacognitive monitoring (Experiment 2) and study-time allocation (Experiment 3) across study–test cycles. Item and associative recognition performance, as well as self-report data, revealed shifts in encoding strategies across trials; these results were used to characterize and evaluate the different strategies that participants employed for cued versus free recall and to assess the optimality of participants’ metacognitive control of encoding strategies. Taken together, these data illustrate a sophisticated form of metacognitive control, in which learners qualitatively shift encoding strategies to match the demands of anticipated tests. PMID:22103783

  5. Evolution of strategies and competition in the international airline industry: a practical analysis using porter's competitive forces model

    OpenAIRE

    Zannoni, Niccolò

    2013-01-01

    This master thesis describes the evolution of the competition and strategies in the international airline industry. It studies the industry before and after deregulation, using the competitive forces model.

  6. Adaptive molecular evolution of the Major Histocompatibility Complex genes, DRA and DQA, in the genus Equus.

    Science.gov (United States)

    Kamath, Pauline L; Getz, Wayne M

    2011-05-18

    Major Histocompatibility Complex (MHC) genes are central to vertebrate immune response and are believed to be under balancing selection by pathogens. This hypothesis has been supported by observations of extremely high polymorphism, elevated nonsynonymous to synonymous base pair substitution rates and trans-species polymorphisms at these loci. In equids, the organization and variability of this gene family has been described, however the full extent of diversity and selection is unknown. As selection is not expected to act uniformly on a functional gene, maximum likelihood codon-based models of selection that allow heterogeneity in selection across codon positions can be valuable for examining MHC gene evolution and the molecular basis for species adaptations. We investigated the evolution of two class II MHC genes of the Equine Lymphocyte Antigen (ELA), DRA and DQA, in the genus Equus with the addition of novel alleles identified in plains zebra (E. quagga, formerly E. burchelli). We found that both genes exhibited a high degree of polymorphism and inter-specific sharing of allele lineages. To our knowledge, DRA allelic diversity was discovered to be higher than has ever been observed in vertebrates. Evidence was also found to support a duplication of the DQA locus. Selection analyses, evaluated in terms of relative rates of nonsynonymous to synonymous mutations (dN/dS) averaged over the gene region, indicated that the majority of codon sites were conserved and under purifying selection (dN

  7. Adaptive molecular evolution of the Major Histocompatibility Complex genes, DRA and DQA, in the genus Equus

    Directory of Open Access Journals (Sweden)

    Getz Wayne M

    2011-05-01

    Full Text Available Abstract Background Major Histocompatibility Complex (MHC genes are central to vertebrate immune response and are believed to be under balancing selection by pathogens. This hypothesis has been supported by observations of extremely high polymorphism, elevated nonsynonymous to synonymous base pair substitution rates and trans-species polymorphisms at these loci. In equids, the organization and variability of this gene family has been described, however the full extent of diversity and selection is unknown. As selection is not expected to act uniformly on a functional gene, maximum likelihood codon-based models of selection that allow heterogeneity in selection across codon positions can be valuable for examining MHC gene evolution and the molecular basis for species adaptations. Results We investigated the evolution of two class II MHC genes of the Equine Lymphocyte Antigen (ELA, DRA and DQA, in the genus Equus with the addition of novel alleles identified in plains zebra (E. quagga, formerly E. burchelli. We found that both genes exhibited a high degree of polymorphism and inter-specific sharing of allele lineages. To our knowledge, DRA allelic diversity was discovered to be higher than has ever been observed in vertebrates. Evidence was also found to support a duplication of the DQA locus. Selection analyses, evaluated in terms of relative rates of nonsynonymous to synonymous mutations (dN/dS averaged over the gene region, indicated that the majority of codon sites were conserved and under purifying selection (dN dS. However, the most likely evolutionary codon models allowed for variable rates of selection across codon sites at both loci and, at the DQA, supported the hypothesis of positive selection acting on specific sites. Conclusions Observations of elevated genetic diversity and trans-species polymorphisms supported the conclusion that balancing selection may be acting on these loci. Furthermore, at the DQA, positive selection was

  8. On e-business strategy planning and performance evaluation: An adaptive algorithmic managerial approach

    Directory of Open Access Journals (Sweden)

    Alexandra Lipitakis

    2017-07-01

    Full Text Available A new e-business strategy planning and performance evaluation scheme based on adaptive algorithmic modelling techniques is presented. The effect of financial and non-financial performance of organizations on e-business strategy planning is investigated. The relationships between the four strategic planning parameters are examined, the directions of these relationships are given and six additional basic components are also considered. The new conceptual model has been constructed for e-business strategic planning and performance evaluation and an adaptive algorithmic modelling approach is presented. The new adaptive algorithmic modelling scheme including eleven dynamic modules, can be optimized and used effectively in e-business strategic planning and strategic planning evaluation of various e-services in very large organizations and businesses. A synoptic statistical analysis and comparative numerical results for the case of UK and Greece are given. The proposed e-business models indicate how e-business strategic planning may affect financial and non-financial performance in business and organizations by exploring whether models which are used for strategy planning can be applied to e-business planning and whether these models would be valid in different environments. A conceptual model has been constructed and qualitative research methods have been used for testing a predetermined number of considered hypotheses. The proposed models have been tested in the UK and Greece and the conclusions including numerical results and statistical analyses indicated existing relationships between considered dependent and independent variables. The proposed e-business models are expected to contribute to e-business strategy planning of businesses and organizations and managers should consider applying these models to their e-business strategy planning to improve their companies’ performances. This research study brings together elements of e

  9. Possible impacts of sea level rise on disease transmission and potential adaptation strategies, a review.

    Science.gov (United States)

    Dvorak, Ana C; Solo-Gabriele, Helena M; Galletti, Andrea; Benzecry, Bernardo; Malone, Hannah; Boguszewski, Vicki; Bird, Jason

    2018-04-18

    Sea levels are projected to rise in response to climate change, causing the intrusion of sea water into land. In flat coastal regions, this would generate an increase in shallow water covered areas with limited circulation. This scenario raises a concern about the consequences it could have on human health, specifically the possible impacts on disease transmission. In this review paper we identified three categories of diseases which are associated with water and whose transmission can be affected by sea level rise. These categories include: mosquitoborne diseases, naturalized organisms (Vibrio spp. and toxic algae), and fecal-oral diseases. For each disease category, we propose comprehensive adaptation strategies that would help minimize possible health risks. Finally, the City of Key West, Florida is analyzed as a case study, due to its inherent vulnerability to sea level rise. Current and projected adaptation techniques are discussed as well as the integration of additional recommendations, focused on disease transmission control. Given that sea level rise will likely continue into the future, the promotion and implementation of positive adaptation strategies is necessary to ensure community resilience. Copyright © 2018 Elsevier Ltd. All rights reserved.

  10. Implementing a WIC-Based Intervention to Promote Exclusive Breastfeeding: Challenges, Facilitators, and Adaptive Strategies.

    Science.gov (United States)

    Eldridge, Johanna D; Hartnett, Josette O; Lee, Furrina F; Sekhobo, Jackson P; Edmunds, Lynn S

    Understand factors that contributed to the implementation of a successful multicomponent intervention to promote exclusive breastfeeding (EBF) within Special Supplemental Nutrition Program for Woman, Infants, and Children (WIC) clinics. Qualitative study of staff implementers' experiences using implementation status reports, facilitated group discussion immediately after implementation, and WIC administrative data. WIC staff from 12 clinics participated in an EBF Learning Community composed of 8 intervention trainings and ongoing support from trainers and peers. A total of 47 WIC staff including 11 directors, 20 other administrators, 8 nutritionists, and 6 peer counselors. A WIC-integrated EBF promotion initiative, supported through a Learning Community, composed of prenatal screening, tailored trimester-specific counseling, and timely postpartum follow-up. Challenges and facilitators to implementation within clinics. Iterative qualitative analysis using directed, emergent, and thematic coding. Implementation experiences were characterized by (1) perceived benefits of implementation, including improved EBF knowledge and counseling confidence among staff; and (2) managing implementation, including responding to challenges posed by clinic settings (resources, routine practices, values, and perceptions of mothers) through strategies such as adapting clinic practices and intervention components. Implementation was shaped by clinic setting and adaptive strategies. Future WIC interventions may benefit from formal consideration of intervention fit with local clinic setting and allowable adaptations. Copyright © 2017 Society for Nutrition Education and Behavior. Published by Elsevier Inc. All rights reserved.

  11. Adaptive Optics Facility: control strategy and first on-sky results of the acquisition sequence

    Science.gov (United States)

    Madec, P.-Y.; Kolb, J.; Oberti, S.; Paufique, J.; La Penna, P.; Hackenberg, W.; Kuntschner, H.; Argomedo, J.; Kiekebusch, M.; Donaldson, R.; Suarez, M.; Arsenault, R.

    2016-07-01

    The Adaptive Optics Facility is an ESO project aiming at converting Yepun, one of the four 8m telescopes in Paranal, into an adaptive telescope. This is done by replacing the current conventional secondary mirror of Yepun by a Deformable Secondary Mirror (DSM) and attaching four Laser Guide Star (LGS) Units to its centerpiece. In the meantime, two Adaptive Optics (AO) modules have been developed incorporating each four LGS WaveFront Sensors (WFS) and one tip-tilt sensor used to control the DSM at 1 kHz frame rate. The four LGS Units and one AO module (GRAAL) have already been assembled on Yepun. Besides the technological challenge itself, one critical area of AOF is the AO control strategy and its link with the telescope control, including Active Optics used to shape M1. Another challenge is the request to minimize the overhead due to AOF during the acquisition phase of the observation. This paper presents the control strategy of the AOF. The current control of the telescope is first recalled, and then the way the AO control makes the link with the Active Optics is detailed. Lab results are used to illustrate the expected performance. Finally, the overall AOF acquisition sequence is presented as well as first results obtained on sky with GRAAL.

  12. Climate Change Adaptation Strategies and Farm-level Efficiency in Food Crop Production in Southwestern, Nigeria

    Directory of Open Access Journals (Sweden)

    Otitoju, MA.

    2014-01-01

    Full Text Available Food crop yields depend largely on prevailing climate conditions, especially in Africa, where rain-fed agriculture predominate. The extent to which climate impacts are felt depends principally on the adaptation measures used by farmers. This study focused on the effect of climate change adaptation strategies on farm-level technical efficiency. The study used primary data collected from 360 randomly selected farmers in Southwest Nigeria. Cobb-Douglass stochastic frontier production model was used to analyse the data. Multiple cropping, land fragmentation, multiple planting dates, mulching and cover cropping were the major climate change adaptation strategies employed by the farmers. While land fragmentation and multiple planting dates had significant positive relationships, years of climate change awareness and social capital had significant inverse relationships, with technical inefficiency. This may be because while land fragmentation may hinder farm mechanization, multiple planting dates may increase the monotonousness and drudgery of farming. On the other hand, social capital and climate change awareness could help ameliorate the effects of, particularly, land fragmentation through resource pooling. It is therefore recommended that the farmers be encouraged to form cooperative societies so as to leverage their resource status through collective efforts.

  13. Evolutionary genomics and adaptive evolution of the Hedgehog gene family (Shh, Ihh and Dhh in vertebrates.

    Directory of Open Access Journals (Sweden)

    Joana Pereira

    Full Text Available The Hedgehog (Hh gene family codes for a class of secreted proteins composed of two active domains that act as signalling molecules during embryo development, namely for the development of the nervous and skeletal systems and the formation of the testis cord. While only one Hh gene is found typically in invertebrate genomes, most vertebrates species have three (Sonic hedgehog--Shh; Indian hedgehog--Ihh; and Desert hedgehog--Dhh, each with different expression patterns and functions, which likely helped promote the increasing complexity of vertebrates and their successful diversification. In this study, we used comparative genomic and adaptive evolutionary analyses to characterize the evolution of the Hh genes in vertebrates following the two major whole genome duplication (WGD events. To overcome the lack of Hh-coding sequences on avian publicly available databases, we used an extensive dataset of 45 avian and three non-avian reptilian genomes to show that birds have all three Hh paralogs. We find suggestions that following the WGD events, vertebrate Hh paralogous genes evolved independently within similar linkage groups and under different evolutionary rates, especially within the catalytic domain. The structural regions around the ion-binding site were identified to be under positive selection in the signaling domain. These findings contrast with those observed in invertebrates, where different lineages that experienced gene duplication retained similar selective constraints in the Hh orthologs. Our results provide new insights on the evolutionary history of the Hh gene family, the functional roles of these paralogs in vertebrate species, and on the location of mutational hotspots.

  14. Evolutionary genomics and adaptive evolution of the Hedgehog gene family (Shh, Ihh and Dhh) in vertebrates.

    Science.gov (United States)

    Pereira, Joana; Johnson, Warren E; O'Brien, Stephen J; Jarvis, Erich D; Zhang, Guojie; Gilbert, M Thomas P; Vasconcelos, Vitor; Antunes, Agostinho

    2014-01-01

    The Hedgehog (Hh) gene family codes for a class of secreted proteins composed of two active domains that act as signalling molecules during embryo development, namely for the development of the nervous and skeletal systems and the formation of the testis cord. While only one Hh gene is found typically in invertebrate genomes, most vertebrates species have three (Sonic hedgehog--Shh; Indian hedgehog--Ihh; and Desert hedgehog--Dhh), each with different expression patterns and functions, which likely helped promote the increasing complexity of vertebrates and their successful diversification. In this study, we used comparative genomic and adaptive evolutionary analyses to characterize the evolution of the Hh genes in vertebrates following the two major whole genome duplication (WGD) events. To overcome the lack of Hh-coding sequences on avian publicly available databases, we used an extensive dataset of 45 avian and three non-avian reptilian genomes to show that birds have all three Hh paralogs. We find suggestions that following the WGD events, vertebrate Hh paralogous genes evolved independently within similar linkage groups and under different evolutionary rates, especially within the catalytic domain. The structural regions around the ion-binding site were identified to be under positive selection in the signaling domain. These findings contrast with those observed in invertebrates, where different lineages that experienced gene duplication retained similar selective constraints in the Hh orthologs. Our results provide new insights on the evolutionary history of the Hh gene family, the functional roles of these paralogs in vertebrate species, and on the location of mutational hotspots.

  15. Evolution and Adaptation of Phytoplankton Photosynthetic Pathways to perturbations of the geological carbon system

    Science.gov (United States)

    Rickaby, R. E.; Young, J. N.; Hermoso, M.; Heureux, A.; McCLelland, H.; Lee, R.; Eason Hubbard, M.

    2012-12-01

    The ocean and atmosphere carbon system has varied greatly over geological history both in response to initial evolutionary innovation, and as a driver of adaptive change. Here we establish that positive selection in Rubisco, the most abundant enzyme on the Earth responsible for all photosynthetic carbon fixation, occurred early in Earth's history, and basal to the radiation of the modern marine algal groups. Our signals of positive selection appear to be triggered by changing intracellular concentrations of carbon dioxide (CO2) due to the emergence of carbon concentrating mechanisms between 1.56 and 0.41 Ba in response to declining atmospheric CO2 . We contend that, at least in terms of carbon, phytoplankton generally were well poised to manage subsequent abrupt carbon cycle perturbations. The physiological pathways for optimising carbon acquisition across a wide range of ambient carbon dioxide concentrations had already been established and were genetically widespread across open ocean phytoplankton groups. We will further investigate some case studies from the Mesozoic and Cenozoic abrupt carbon cycle excursions using isotopic tools to probe the community photosynthetic response and demonstrate the flexibility of phytoplankton photosynthesis in the face of major perturbations. In particular, an unprecedented resolution record across the Toarcian (Early Jurassic) carbon isotope excursion in the Paris Basin reveals a selection and evolution towards a community reliant solely on diffusive carbon dioxide supply for photosynthesis at the height of the excursion at 1500-2500 ppm CO2. The continued flourishing of the phytoplankton biological pump throughout this excursion was able to remove the excess carbon injected into the water column in less than 45 kyrs.

  16. Hybridization and adaptive evolution of diverse Saccharomyces species for cellulosic biofuel production.

    Science.gov (United States)

    Peris, David; Moriarty, Ryan V; Alexander, William G; Baker, EmilyClare; Sylvester, Kayla; Sardi, Maria; Langdon, Quinn K; Libkind, Diego; Wang, Qi-Ming; Bai, Feng-Yan; Leducq, Jean-Baptiste; Charron, Guillaume; Landry, Christian R; Sampaio, José Paulo; Gonçalves, Paula; Hyma, Katie E; Fay, Justin C; Sato, Trey K; Hittinger, Chris Todd

    2017-01-01

    Lignocellulosic biomass is a common resource across the globe, and its fermentation offers a promising option for generating renewable liquid transportation fuels. The deconstruction of lignocellulosic biomass releases sugars that can be fermented by microbes, but these processes also produce fermentation inhibitors, such as aromatic acids and aldehydes. Several research projects have investigated lignocellulosic biomass fermentation by the baker's yeast Saccharomyces cerevisiae . Most projects have taken synthetic biological approaches or have explored naturally occurring diversity in S. cerevisiae to enhance stress tolerance, xylose consumption, or ethanol production. Despite these efforts, improved strains with new properties are needed. In other industrial processes, such as wine and beer fermentation, interspecies hybrids have combined important traits from multiple species, suggesting that interspecies hybridization may also offer potential for biofuel research. To investigate the efficacy of this approach for traits relevant to lignocellulosic biofuel production, we generated synthetic hybrids by crossing engineered xylose-fermenting strains of S. cerevisiae with wild strains from various Saccharomyces species. These interspecies hybrids retained important parental traits, such as xylose consumption and stress tolerance, while displaying intermediate kinetic parameters and, in some cases, heterosis (hybrid vigor). Next, we exposed them to adaptive evolution in ammonia fiber expansion-pretreated corn stover hydrolysate and recovered strains with improved fermentative traits. Genome sequencing showed that the genomes of these evolved synthetic hybrids underwent rearrangements, duplications, and deletions. To determine whether the genus Saccharomyces contains additional untapped potential, we screened a genetically diverse collection of more than 500 wild, non-engineered Saccharomyces isolates and uncovered a wide range of capabilities for traits relevant to

  17. Interacting proteins on human spermatozoa: adaptive evolution of the binding of semenogelin I to EPPIN.

    Directory of Open Access Journals (Sweden)

    Erick J R Silva

    Full Text Available Semenogelin I (SEMG1 is found in human semen coagulum and on the surface of spermatozoa bound to EPPIN. The physiological significance of the SEMG1/EPPIN interaction on the surface of spermatozoa is its capacity to modulate sperm progressive motility. The present study investigates the hypothesis that the interacting surface of SEMG1 and EPPIN co-evolved within the Hominoidea time scale, as a result of adaptive pressures applied by their roles in sperm protection and reproductive fitness. Our results indicate that some amino acid residues of SEMG1 and EPPIN possess a remarkable deficiency of variation among hominoid primates. We observe a distinct residue change unique to humans within the EPPIN sequence containing a SEMG1 interacting surface, namely His92. In addition, Bayes Empirical Bayes analysis for positive selection indicates that the SEMG1 Cys239 residue underwent positive selection in humans, probably as a consequence of its role in increasing the binding affinity of these interacting proteins. We confirm the critical role of Cys239 residue for SEMG1 binding to EPPIN and inhibition of sperm motility by showing that recombinant SEMG1 mutants in which Cys239 residue was changed to glycine, aspartic acid, histidine, serine or arginine have reduced capacity to interact to EPPIN and to inhibit human sperm motility in vitro. In conclusion, our results indicate that EPPIN and SEMG1 rapidly co-evolved in primates due to their critical role in the modulation of sperm motility in the semen coagulum, providing unique insights into the molecular co-evolution of sperm surface interacting proteins.

  18. Testing Biological Hypotheses with Embodied Robots: Adaptations, Accidents, and By-Products in the Evolution of Vertebrates

    OpenAIRE

    Roberts, Sonia F.; Hirokawa, Jonathan; Rosenblum, Hannah G.; Sakhtah, Hassan; Gutierrez, Andres A.; Porter, Marianne E.; Long, John H.

    2014-01-01

    Evolutionary robotics allows biologists to test hypotheses about extinct animals. In our case, we modeled some of the first vertebrates, jawless fishes, in order to study the evolution of the trait after which vertebrates are named: vertebrae. We tested the hypothesis that vertebrae are an adaptation for enhanced feeding and fleeing performance. We created a population of autonomous embodied robots, Preyro, in which the number of vertebrae, N, were free to evolve. In addition, two other trait...

  19. Implementing adaptation strategies by legal, economic and planning instruments on climate change

    Energy Technology Data Exchange (ETDEWEB)

    Albrecht, Eike; Missler-Behr, Magdalena; Schmidt, Michael; Spyra, Simon P.N. (eds.) [Brandenburg Univ. of Technology Cottbus-Senftenberg (Germany)

    2014-07-01

    The causes and effects of climate change are just as varied as the proposed solutions and approaches for dealing with the problem. Given the global character of climate change, comprehensive global cooperation is called for that leads to effective and appropriate international action in accordance with the respective responsibilities. These will inevitably differ depending on the capabilities and the social and economic situations of the respective actors. The contributions in this book present a variety of ideas, approaches and tools regarding the adaptation to climate change in specific countries and regions. In addition to examining (existing) legal instruments, they also focus on the implementation of economic instruments and planning tools, as well as their (further) development. Rather than simply discussing strategies to counteract climate change by reducing emissions, the authors also search for ways of actively adapting to climate change.

  20. Invasion strategies in clonal aquatic plants: Are phenotypic differences caused by phenotypic plasticity or local adaptation?

    DEFF Research Database (Denmark)

    Riis, Tenna; Lambertini, Carla; Olesen, Birgit

    2010-01-01

    conditions and plant morphological characteristics. Conclusions: The results indicate that at the current stage of spread into New Zealand, the primary adaptive strategy of these three invasive macrophytes is phenotypic plasticity. However, while limited, the possibility that genetic diversity between......Background and Aims: The successful spread of invasive plants in new environments is often linked to multiple introductions and a diverse gene pool that facilitates local adaptation to variable environmental conditions. For clonal plants, however, phenotypic plasticity may be equally important....... Methods: Field populations with a large phenotypic variety were sampled in a range of lakes and streams with different chemical and physical properties. The phenotypic plasticity of the species before and after cultivation was studied in a common garden growth experiment, and the genetic diversity...

  1. Implementing adaptation strategies by legal, economic and planning instruments on climate change

    International Nuclear Information System (INIS)

    Albrecht, Eike; Missler-Behr, Magdalena; Schmidt, Michael; Spyra, Simon P.N.

    2014-01-01

    The causes and effects of climate change are just as varied as the proposed solutions and approaches for dealing with the problem. Given the global character of climate change, comprehensive global cooperation is called for that leads to effective and appropriate international action in accordance with the respective responsibilities. These will inevitably differ depending on the capabilities and the social and economic situations of the respective actors. The contributions in this book present a variety of ideas, approaches and tools regarding the adaptation to climate change in specific countries and regions. In addition to examining (existing) legal instruments, they also focus on the implementation of economic instruments and planning tools, as well as their (further) development. Rather than simply discussing strategies to counteract climate change by reducing emissions, the authors also search for ways of actively adapting to climate change.

  2. Availability of public goods shapes the evolution of competing metabolic strategies.

    Science.gov (United States)

    Bachmann, Herwig; Fischlechner, Martin; Rabbers, Iraes; Barfa, Nakul; Branco dos Santos, Filipe; Molenaar, Douwe; Teusink, Bas

    2013-08-27

    Tradeoffs provide a rationale for the outcome of natural selection. A prominent example is the negative correlation between the growth rate and the biomass yield in unicellular organisms. This tradeoff leads to a dilemma, where the optimization of growth rate is advantageous for an individual, whereas the optimization of the biomass yield would be advantageous for a population. High-rate strategies are observed in a broad variety of organisms such as Escherichia coli, yeast, and cancer cells. Growth in suspension cultures favors fast-growing organisms, whereas spatial structure is of importance for the evolution of high-yield strategies. Despite this realization, experimental methods to directly select for increased yield are lacking. We here show that the serial propagation of a microbial population in a water-in-oil emulsion allows selection of strains with increased biomass yield. The propagation in emulsion creates a spatially structured environment where the growth-limiting substrate is privatized for populations founded by individual cells. Experimental evolution of several isogenic Lactococcus lactis strains demonstrated the existence of a tradeoff between growth rate and biomass yield as an apparent Pareto front. The underlying mutations altered glucose transport and led to major shifts between homofermentative and heterofermentative metabolism, accounting for the changes in metabolic efficiency. The results demonstrated the impact of privatizing a public good on the evolutionary outcome between competing metabolic strategies. The presented approach allows the investigation of fundamental questions in biology such as the evolution of cooperation, cell-cell interactions, and the relationships between environmental and metabolic constraints.

  3. Adaptive coping strategies of affected family members of a relative with substance misuse: A qualitative study.

    Science.gov (United States)

    McCann, Terence V; Lubman, Dan I

    2018-01-01

    To explore the coping strategies used by affected family members of a relative with substance misuse. Families play an important role in supporting a relative with substance misuse. However, the experience often has an adverse effect on their general well-being, the extent of which depends largely on their coping strategies. An interpretative phenomenological analysis study. Data were collected between January - December 2015. Semistructured, audio-recorded qualitative interviews were conducted with 31 affected family members. Three main themes and related subthemes were abstracted from the data illustrating how participants coped with their relative's substance misuse: (1) Seeking timely access to evidence-based information; (2) Enhancing personal coping strategies and (3) Accessing informal and formal support. Greater investment is needed in support services for affected family members, particularly in regional and rural areas. A wide range of accessible evidence-based information and informal and formal support, including telephone and online support, is needed to assist them to cope in this crucial support-giving role. Affected family members need to adopt a flexible set of coping strategies while supporting a relative with substance misuse. Family and friends, alcohol and other drug services, mental health nurses and other clinicians have a critical role providing emotional, instrumental and educational support to affected family members to enhance their adaptive coping strategies. © 2017 John Wiley & Sons Ltd.

  4. Evolution of learned strategy choice in a frequency-dependent game.

    Science.gov (United States)

    Katsnelson, Edith; Motro, Uzi; Feldman, Marcus W; Lotem, Arnon

    2012-03-22

    In frequency-dependent games, strategy choice may be innate or learned. While experimental evidence in the producer-scrounger game suggests that learned strategy choice may be common, a recent theoretical analysis demonstrated that learning by only some individuals prevents learning from evolving in others. Here, however, we model learning explicitly, and demonstrate that learning can easily evolve in the whole population. We used an agent-based evolutionary simulation of the producer-scrounger game to test the success of two general learning rules for strategy choice. We found that learning was eventually acquired by all individuals under a sufficient degree of environmental fluctuation, and when players were phenotypically asymmetric. In the absence of sufficient environmental change or phenotypic asymmetries, the correct target for learning seems to be confounded by game dynamics, and innate strategy choice is likely to be fixed in the population. The results demonstrate that under biologically plausible conditions, learning can easily evolve in the whole population and that phenotypic asymmetry is important for the evolution of learned strategy choice, especially in a stable or mildly changing environment.

  5. Multi-objective optimization of p-xylene oxidation process using an improved self-adaptive differential evolution algorithm

    Institute of Scientific and Technical Information of China (English)

    Lili Tao; Bin Xu; Zhihua Hu; Weimin Zhong

    2017-01-01

    The rise in the use of global polyester fiber contributed to strong demand of the Terephthalic acid (TPA). The liquid-phase catalytic oxidation of p-xylene (PX) to TPA is regarded as a critical and efficient chemical process in industry [1]. PX oxidation reaction involves many complex side reactions, among which acetic acid combustion and PX combustion are the most important. As the target product of this oxidation process, the quality and yield of TPA are of great concern. However, the improvement of the qualified product yield can bring about the high energy consumption, which means that the economic objectives of this process cannot be achieved simulta-neously because the two objectives are in conflict with each other. In this paper, an improved self-adaptive multi-objective differential evolution algorithm was proposed to handle the multi-objective optimization prob-lems. The immune concept is introduced to the self-adaptive multi-objective differential evolution algorithm (SADE) to strengthen the local search ability and optimization accuracy. The proposed algorithm is successfully tested on several benchmark test problems, and the performance measures such as convergence and divergence metrics are calculated. Subsequently, the multi-objective optimization of an industrial PX oxidation process is carried out using the proposed immune self-adaptive multi-objective differential evolution algorithm (ISADE). Optimization results indicate that application of ISADE can greatly improve the yield of TPA with low combustion loss without degenerating TA quality.

  6. Implementation of Evolution Strategies (ES Algorithm to Optimization Lovebird Feed Composition

    Directory of Open Access Journals (Sweden)

    Agung Mustika Rizki

    2017-05-01

    Full Text Available Lovebird current society, especially popular among bird lovers. Some people began to try to develop the cultivation of these birds. In the cultivation process to consider the composition of feed to produce a quality bird. Determining the feed is not easy because it must consider the cost and need for vitamin Lovebird. This problem can be solved by the algorithm Evolution Strategies (ES. Based on test results obtained optimal fitness value of 0.3125 using a population size of 100 and optimal fitness value of 0.3267 in the generation of 1400. 

  7. Multi-morbidity, disability and adaptation strategies among community-dwelling adults aged 75 years and older.

    Science.gov (United States)

    Yuen, Hon K; Vogtle, Laura K

    2016-10-01

    The impact of multi-morbidity and disability on the use of adaptation strategies in older adults has not been well researched. This study investigated categories of adaptation strategies that community-dwelling older adults use to complete their daily activities, identified factors that are associated with the use of behavioral adaptations, and examined the relationship among multi-morbidity, disability and adaptation strategies in this population. A mixed methods research design was used. 105 community-dwelling older adults with ages ranging from 75 to 94 years completed a questionnaire and semi-structured interview on types of chronic illnesses (multi-morbidity), amount of difficulty in completing daily activities (degree of disability), and types of behavioral efforts made to complete daily activities that are challenging (adaptation strategies). The model of selective optimization with compensation (SOC) was used to categorize these strategies. The findings revealed that older adults use a wide range of adaptations with compensation and selection the most (40.4%) and least (16.5%) frequently reported respectively. Degree of disability was uniquely associated with the frequency of using SOC strategies while controlling for other factors. Furthermore, degree of disability was a mediator for multi-morbidity in predicting frequency of using SOC strategies. The findings support that older adults using behavioral adaptations to cope with functional decline is prevalent. Knowing the types of adaptation that older adults employed and the indirect relationship between multi-morbidity and frequency of using SOC strategies, with degree of disability as the mediator will be helpful in planning interventions and prevention programs for educating older adults. Copyright © 2016 Elsevier Inc. All rights reserved.

  8. Climate change adaptation strategies for federal forests of the Pacific Northwest, USA: ecological, policy, and socio-economic perspectives

    Science.gov (United States)

    Thomas A. Spies; Thomas W. Giesen; Frederick J. Swanson; Jerry F. Franklin; Denise Lach; K. Norman. Johnson

    2010-01-01

    Conserving biological diversity in a changing climate poses major challenges for land managers and society. Effective adaptive strategies for dealing with climate change require a socioecological systems perspective. We highlight some of the projected ecological responses to climate change in the Pacific Northwest, U.S.A and identify possible adaptive actions that...

  9. Cooperative Learning Groups and the Evolution of Human Adaptability : (Another Reason) Why Hermits Are Rare in Tonga and Elsewhere.

    Science.gov (United States)

    Bell, Adrian Viliami; Hernandez, Daniel

    2017-03-01

    Understanding the prevalence of adaptive culture in part requires understanding the dynamics of learning. Here we explore the adaptive value of social learning in groups and how formal social groups function as effective mediums of information exchange. We discuss the education literature on Cooperative Learning Groups (CLGs), which outlines the potential of group learning for enhancing learning outcomes. Four qualities appear essential for CLGs to enhance learning: (1) extended conversations, (2) regular interactions, (3) gathering of experts, and (4) incentives for sharing knowledge. We analyze these four qualities within the context of a small-scale agricultural society using data we collected in 2010 and 2012. Through an analysis of surveys, interviews, and observations in the Tongan islands, we describe the role CLGs likely plays in facilitating individuals' learning of adaptive information. Our analysis of group affiliation, membership, and topics of conversation suggest that the first three CLG qualities reflect conditions for adaptive learning in groups. We utilize ethnographic anecdotes to suggest the fourth quality is also conducive to adaptive group learning. Using an evolutionary model, we further explore the scope for CLGs outside the Tongan socioecological context. Model analysis shows that environmental volatility and migration rates among human groups mediate the scope for CLGs. We call for wider attention to how group structure facilitates learning in informal settings, which may be key to assessing the contribution of groups to the evolution of complex, adaptive culture.

  10. Multilocus analyses reveal little evidence for lineage-wide adaptive evolution within major clades of soft pines (Pinus subgenus Strobus)

    Science.gov (United States)

    Andrew J. Eckert; Andrew D. Bower; Kathleen D. Jermstad; Jill L. Wegrzyn; Brian J. Knaus; John V. Syring; David B. Neale

    2013-01-01

    Estimates from molecular data for the fraction of new nonsynonymous mutations that are adaptive vary strongly across plant species. Much of this variation is due to differences in life history strategies as they influence the effective population size (Ne). Ample variation for these estimates, however, remains even when...

  11. Thermotolerant Yeast Strains Adapted by Laboratory Evolution Show Trade-Off at Ancestral Temperatures and Preadaptation to Other Stresses

    DEFF Research Database (Denmark)

    Caspeta, Luis; Nielsen, Jens

    2015-01-01

    adaptive laboratory evolution, we previously isolated seven Saccharomyces cerevisiae strains with improved growth at 40°C. Here, we show that genetic adaptations to high temperature caused a growth trade-off at ancestral temperatures, reduced cellular functions, and improved tolerance of other stresses...... in the ancestral strain. The latter is an advantageous attribute for acquiring thermotolerance and correlates with the reduction of yeast functions associated with loss of respiration capacity. This trait caused glycerol overproduction that was associated with the growth trade-off at ancestral temperatures....... In combination with altered sterol composition of cellular membranes, glycerol overproduction was also associated with yeast osmotolerance and improved tolerance of high concentrations of glucose and ethanol. Our study shows that thermal adaptation of yeast is suitable for improving yeast resistance...

  12. Intrasexual competition facilitates the evolution of alternative mating strategies in a colour polymorphic fish.

    Science.gov (United States)

    Hurtado-Gonzales, Jorge L; Uy, J Albert C

    2010-12-23

    Intense competition for access to females can lead to males exploiting different components of sexual selection, and result in the evolution of alternative mating strategies (AMSs). Males of Poecilia parae, a colour polymorphic fish, exhibit five distinct phenotypes: drab-coloured (immaculata), striped (parae), structural-coloured (blue) and carotenoid-based red and yellow morphs. Previous work indicates that immaculata males employ a sneaker strategy, whereas the red and yellow morphs exploit female preferences for carotenoid-based colours. Mating strategies favouring the maintenance of the other morphs remain to be determined. Here, we report the role of agonistic male-male interactions in influencing female mating preferences and male mating success, and in facilitating the evolution of AMSs. Our study reveals variation in aggressiveness among P. parae morphs during indirect and direct interactions with sexually receptive females. Two morphs, parae and yellow, use aggression to enhance their mating success (i.e., number of copulations) by 1) directly monopolizing access to females, and 2) modifying female preferences after winning agonistic encounters. Conversely, we found that the success of the drab-coloured immaculata morph, which specializes in a sneak copulation strategy, relies in its ability to circumvent both male aggression and female choice when facing all but yellow males. Strong directional selection is expected to deplete genetic variation, yet many species show striking genetically-based polymorphisms. Most studies evoke frequency dependent selection to explain the persistence of such variation. Consistent with a growing body of evidence, our findings suggest that a complex form of balancing selection may alternatively explain the evolution and maintenance of AMSs in a colour polymorphic fish. In particular, this study demonstrates that intrasexual competition results in phenotypically distinct males exhibiting clear differences in their levels of

  13. Intrasexual competition facilitates the evolution of alternative mating strategies in a colour polymorphic fish

    Directory of Open Access Journals (Sweden)

    Uy J Albert C

    2010-12-01

    Full Text Available Abstract Background Intense competition for access to females can lead to males exploiting different components of sexual selection, and result in the evolution of alternative mating strategies (AMSs. Males of Poecilia parae, a colour polymorphic fish, exhibit five distinct phenotypes: drab-coloured (immaculata, striped (parae, structural-coloured (blue and carotenoid-based red and yellow morphs. Previous work indicates that immaculata males employ a sneaker strategy, whereas the red and yellow morphs exploit female preferences for carotenoid-based colours. Mating strategies favouring the maintenance of the other morphs remain to be determined. Here, we report the role of agonistic male-male interactions in influencing female mating preferences and male mating success, and in facilitating the evolution of AMSs. Results Our study reveals variation in aggressiveness among P. parae morphs during indirect and direct interactions with sexually receptive females. Two morphs, parae and yellow, use aggression to enhance their mating success (i.e., number of copulations by 1 directly monopolizing access to females, and 2 modifying female preferences after winning agonistic encounters. Conversely, we found that the success of the drab-coloured immaculata morph, which specializes in a sneak copulation strategy, relies in its ability to circumvent both male aggression and female choice when facing all but yellow males. Conclusions Strong directional selection is expected to deplete genetic variation, yet many species show striking genetically-based polymorphisms. Most studies evoke frequency dependent selection to explain the persistence of such variation. Consistent with a growing body of evidence, our findings suggest that a complex form of balancing selection may alternatively explain the evolution and maintenance of AMSs in a colour polymorphic fish. In particular, this study demonstrates that intrasexual competition results in phenotypically distinct

  14. Research on Adaptive Dual-Mode Switch Control Strategy for Vehicle Maglev Flywheel Battery

    Directory of Open Access Journals (Sweden)

    Hui Gao

    2015-01-01

    Full Text Available Because of the jamming signal is real-time changeable and control algorithm cannot timely tracking control flywheel rotor, this paper takes vehicle maglev flywheel battery as the research object. One kind of dual-model control strategy is developed based on the analysis of the vibration response impact of the flywheel battery control system. In view of the complex foundation vibration problems of electric vehicles, the nonlinear dynamic simulation model of vehicle maglev flywheel battery is solved. Through analyzing the nonlinear vibration response characteristics, one kind of dual-mode adaptive hybrid control strategy based on H∞ control and unbalance displacement feed-forward compensation control is presented and a real-time switch controller is designed. The reliable hybrid control is implemented, and the stability in the process of real-time switch is solved. The results of this project can provide important basic theory support for the research of vehicle maglev flywheel battery control system.

  15. A Reactive Power Based Reference Model for Adaptive Control Strategy in a SEIG

    Directory of Open Access Journals (Sweden)

    M. A. Taghikhani

    2018-02-01

    Full Text Available In this paper, a new control strategy is proposed for a three-phase squirrel-cage self-excited induction generator (SEIG connected to a variable speed wind turbine in autonomous mode. In order to improve the dynamic performance of the mentioned vector control system, a model reference adaptive controller is used for online rotor time constant estimation. Thus, the main drawbacks of this method, which include the effects of the changes in machine parameters on rotor flux estimation, slip speed, the creation of instability problems and the system leaving vector control mode, are resolved. In this control strategy, a PI controller is used to control the dc voltage and three similar hysteresis current controllers (HCC are used to control the switching of IGBTs. The results of the dynamic simulation indicate the desirable performance of the proposed system.

  16. Effect of migration based on strategy and cost on the evolution of cooperation

    International Nuclear Information System (INIS)

    Li, Yan; Ye, Hang

    2015-01-01

    Highlights: •Propose a migration based on strategy and cost in the Prisoner’s Dilemma Game. •The level of cooperation without mutation is higher than that with mutation. •Increased costs have no effect on the level of cooperation without mutation. •The level of cooperation decreases with the increase in cost with mutation. •An optimal density value ρ resulting in the maximum level of cooperation exists. -- Abstract: Humans consider not only their own ability but also the environment around them during the process of migration. Based on this fact, we introduce migration based on strategy and cost into the Spatial Prisoner’s Dilemma Game on a two-dimensional grid. The migration means that agents cannot move when all of the neighbors are cooperators; otherwise, agents move with a probability related to payoff and cost. The result obtained by the computer simulation shows that the moving mechanism based on strategy and cost improves the level of cooperation in a wide parameter space. This occurs because movement based on strategy effectively keeps the cooperative clusters and because movement based on cost effectively regulates the rate of movement. Both types of movement provide a favorable guarantee for the evolution of stable cooperation under the mutation rate q = 0.0. In addition, we discuss the effectiveness of the migration mechanism in the evolution of cooperation under the mutation rate q = 0.001. The result indicates that a higher level of cooperation is obtained at a lower migration cost, whereas cooperation is suppressed at a higher migration cost. Our work may provide an effective method for understanding the emergence of cooperation in our society

  17. Goal orientation and work role performance: predicting adaptive and proactive work role performance through self-leadership strategies.

    Science.gov (United States)

    Marques-Quinteiro, Pedro; Curral, Luís Alberto

    2012-01-01

    This article explores the relationship between goal orientation, self-leadership dimensions, and adaptive and proactive work role performances. The authors hypothesize that learning orientation, in contrast to performance orientation, positively predicts proactive and adaptive work role performances and that this relationship is mediated by self-leadership behavior-focused strategies. It is posited that self-leadership natural reward strategies and thought pattern strategies are expected to moderate this relationship. Workers (N = 108) from a software company participated in this study. As expected, learning orientation did predict adaptive and proactive work role performance. Moreover, in the relationship between learning orientation and proactive work role performance through self-leadership behavior-focused strategies, a moderated mediation effect was found for self-leadership natural reward and thought pattern strategies. In the end, the authors discuss the results and implications are discussed and future research directions are proposed.

  18. Water supply sustainability and adaptation strategies under anthropogenic and climatic changes of a meso-scale Mediterranean catchment.

    Science.gov (United States)

    Collet, Lila; Ruelland, Denis; Estupina, Valérie Borrell; Dezetter, Alain; Servat, Eric

    2015-12-01

    Assessing water supply sustainability is crucial to meet stakeholders' needs, notably in the Mediterranean. This region has been identified as a climate change hot spot, and as a region where water demand is continuously increasing due to population growth and the expansion of irrigated areas. The Hérault River catchment (2500 km2, France) is a typical example and a negative trend in discharge has been observed since the 1960s. In this context, local stakeholders need to evaluate possible future changes in water allocation capacity in the catchment, using climate change, dam management and water use scenarios. A modelling framework that was already calibrated and validated on this catchment over the last 50 years was used to assess whether water resources could meet water demands at the 2030 horizon for the domestic, agricultural and environmental sectors. Water supply sustainability was evaluated at the sub-basin scale according to priority allocations using a water supply capacity index, frequency of unsatisfactory years as well as the reliability, resilience and sustainability metrics. Water use projections were based on the evolution of population, per-unit water demand, irrigated areas, water supply network efficiency, as well as on the evaluation of a biological flow. Climate projections were based on an increase in temperature up to 2°C and a decrease in daily precipitation by 20%. Adaptation strategies considered reducing per-unit water demand for the domestic sector and the importation of water volume for the agricultural sector. The dissociated effects of water use and climatic constraints on water supply sustainability were evaluated. Results showed that the downstream portions would be the more impacted as they are the most exploited ones. In the domestic sector, sustainability indicators would be more degraded by climate change scenarios than water use constraints. In the agricultural sector the negative impact of water use scenarios would be

  19. Soil mapping and processes models to support climate change mitigation and adaptation strategies: a review

    Science.gov (United States)

    Muñoz-Rojas, Miriam; Pereira, Paulo; Brevik, Eric; Cerda, Artemi; Jordan, Antonio

    2017-04-01

    As agreed in Paris in December 2015, global average temperature is to be limited to "well below 2 °C above pre-industrial levels" and efforts will be made to "limit the temperature increase to 1.5 °C above pre-industrial levels. Thus, reducing greenhouse gas emissions (GHG) in all sectors becomes critical and appropriate sustainable land management practices need to be taken (Pereira et al., 2017). Mitigation strategies focus on reducing the rate and magnitude of climate change by reducing its causes. Complementary to mitigation, adaptation strategies aim to minimise impacts and maximize the benefits of new opportunities. The adoption of both practices will require developing system models to integrate and extrapolate anticipated climate changes such as global climate models (GCMs) and regional climate models (RCMs). Furthermore, integrating climate models driven by socio-economic scenarios in soil process models has allowed the investigation of potential changes and threats in soil characteristics and functions in future climate scenarios. One of the options with largest potential for climate change mitigation is sequestering carbon in soils. Therefore, the development of new methods and the use of existing tools for soil carbon monitoring and accounting have therefore become critical in a global change context. For example, soil C maps can help identify potential areas where management practices that promote C sequestration will be productive and guide the formulation of policies for climate change mitigation and adaptation strategies. Despite extensive efforts to compile soil information and map soil C, many uncertainties remain in the determination of soil C stocks, and the reliability of these estimates depends upon the quality and resolution of the spatial datasets used for its calculation. Thus, better estimates of soil C pools and dynamics are needed to advance understanding of the C balance and the potential of soils for climate change mitigation. Here

  20. A hybrid strategy of offline adaptive planning and online image guidance for prostate cancer radiotherapy

    International Nuclear Information System (INIS)

    Lei Yu; Wu Qiuwen

    2010-01-01

    Offline adaptive radiotherapy (ART) has been used to effectively correct and compensate for prostate motion and reduce the required margin. The efficacy depends on the characteristics of the patient setup error and interfraction motion through the whole treatment; specifically, systematic errors are corrected and random errors are compensated for through the margins. In online image-guided radiation therapy (IGRT) of prostate cancer, the translational setup error and inter-fractional prostate motion are corrected through pre-treatment imaging and couch correction at each fraction. However, the rotation and deformation of the target are not corrected and only accounted for with margins in treatment planning. The purpose of this study was to investigate whether the offline ART strategy is necessary for an online IGRT protocol and to evaluate the benefit of the hybrid strategy. First, to investigate the rationale of the hybrid strategy, 592 cone-beam-computed tomography (CBCT) images taken before and after each fraction for an online IGRT protocol from 16 patients were analyzed. Specifically, the characteristics of prostate rotation were analyzed. It was found that there exist systematic inter-fractional prostate rotations, and they are patient specific. These rotations, if not corrected, are persistent through the treatment fraction, and rotations detected in early fractions are representative of those in later fractions. These findings suggest that the offline adaptive replanning strategy is beneficial to the online IGRT protocol with further margin reductions. Second, to quantitatively evaluate the benefit of the hybrid strategy, 412 repeated helical CT scans from 25 patients during the course of treatment were included in the replanning study. Both low-risk patients (LRP, clinical target volume, CTV = prostate) and intermediate-risk patients (IRP, CTV = prostate + seminal vesicles) were included in the simulation. The contours of prostate and seminal vesicles were