WorldWideScience

Sample records for arbors trade-off material

  1. Nest-building males trade-off material collection costs with territory value

    OpenAIRE

    Bailey, Ida; Morgan, Kate; Oschadleus, D; DeRuiter , SL; Meddle, Simone; Healy, Susan D.

    2016-01-01

    Building a structurally robust nest is crucial for reproductive success in manybirds. However, we know little about the criteria birds use to select material or where they go to collect it. Here we observed the material collection of male cape weaverbirds (Ploceus capensis). Males typically selected long, strong material to build their nests and each male collected material from different locations. Males that built more nests nested in a different area of the colony and flew further to colle...

  2. Nest-building males trade off material collection costs with territory value

    OpenAIRE

    Bailey, Ida E.; Morgan, Kate V.; Oschadleus, H. Dieter; DeRuiter, Stacy L; Meddle, Simone L.; Healy, Susan D.

    2016-01-01

    This work was supported by the BBSRC (BB/I019502/1 to SDH and SLM) and Roslin Institute Strategic Grant funding from the BBSRC (SLM). Building a structurally robust nest is crucial for reproductive success in many birds. However, we know little about the criteria birds use to select material or where they go to collect it. Here we observed the material collection of male Cape Weavers (Ploceus capensis). Males typically selected long, strong material to build their nests and each male colle...

  3. Traits traded off

    NARCIS (Netherlands)

    Rueffler, Claus

    2006-01-01

    The course of evolution is restricted by constraints. A special type of constraint is a trade-off where different traits are negatively correlated. In this situation a mutant type that shows an improvement in one trait suffers from a decreased performance through another trait. In a fixed fitness la

  4. Improving the design of higher-capacity railway tank cars for hazardous materials transport: optimizing the trade-off between weight and safety.

    Science.gov (United States)

    Barkan, Christopher P L

    2008-12-15

    As with many aspects of modern industrial society, decision-makers face trade-offs in considering hazardous materials transportation equipment and practices. Tank cars used for transport of hazardous materials can be made more resistant to damage in accidents through use of a thicker steel tank and other protective features. However, the additional weight of these features reduces the car's capacity and thus its efficiency as a transportation vehicle. In this paper the problem of tank car safety versus weight is developed as a multi-attribute decision problem. North American railroads recently developed specifications for higher capacity tank cars for transportation of hazardous materials including enhanced safety design features. A group of tank car safety design features or "risk reduction options" (RROs) were analyzed with regard to their effect on the conditional probability of release in an accident, and their incremental effect on tank car weight. All possible combinations of these RROs were then analyzed in terms of the reduced release probability per unit of weight increase and the Pareto optimal set of options identified. This set included the combinations of RROs that provided the greatest improvement in safety with the least amount of additional weight for any desired level of tank car weight increase. The analysis was conducted for both non-insulated and insulated tank cars and used two objective functions, minimization of conditional probability of release, and minimization of expected quantity lost, given that a car was derailed in an accident. Sensitivity analyses of the effect of tank car size and use of different objective functions were conducted and the optimality results were found to be robust. The results of this analysis were used by the Association of American Railroads Tank Car Committee to develop new specifications for higher capacity non-insulated and insulated, non-pressure tank cars resulting in an estimated 32% and 24% respective

  5. The hyperspectral imaging trade-off

    DEFF Research Database (Denmark)

    Carstensen, Jens Michael

    structures in these projects. However, hyperspectral imaging is a sampling choice within spectral imaging that typically will impose some trade-offs, and these trade-offs will not be optimal for many applications. The purpose of this presentation is to point out and increase the awareness of these trade-offs...... will show how spectral resolution in these situations can be traded off with improvements in the parameters above....

  6. Breckinridge Project, initial effort. Report XI, Volume III. Critical design areas. [Identification of critical design areas; design or materials problems, trade-off areas, items affecting operability and reliability

    Energy Technology Data Exchange (ETDEWEB)

    None

    1982-01-01

    Several meetings have been held with representatives from Ashland Synthetic Fuels, Inc.; Airco Energy Company, Inc.; Bechtel Group, Inc.; and HRI Engineering, Inc. to identify critical design areas in the Phase Zero work. (Critical design areas are defined as those requiring additional data or further work to finalize design or material selection, to optimize the trade-off between capital investment and operating cost, or to enhance system operability and reliability.) The critical design areas so identified are summarized by plant in this volume of Report XI. Items of a proprietary nature have been omitted from this report, but are included in the limited access version.

  7. Time-Space Trade-Offs

    DEFF Research Database (Denmark)

    Pagter, Jakob Illeborg

    In this dissertation we investigate the complexity of the time-space trade-off for sorting, element distinctness, and similar problems. We contribute new results, techniques, tools, and definitions pertaining to time-space trade-offs for the RAM (Random Access Machine), including new tight upper...... bounds on the time-space trade-off for Sorting in a variety of RAM models and a strong time-space trade-off lower bound for a decision problem in the RAM (in fact the branching program) model. We thus contribute to the general understanding of a number of fundamental combinatorial problems. Time...... and space are the two most fundamental resources studied in the areas of algorithms and computational complexity theory and it is clearly important to study how they are related. In 1966 Cobham founded the area of time-space trade-offs by formally proving the first time-space trade-off—for the language...

  8. Trade-offs: En brugbar tankegang?

    DEFF Research Database (Denmark)

    Zachariassen, Frederik; Liempd, Dennis van

    2010-01-01

    Begrebet ”trade-offs” er et ofte anvendt begreb i erhvervsøkonomien. Specielt indenfor områder som logistik er denne måde at ræsonnere på dominerende. I mange logistiske problemstillinger findes der således tilsyneladende klart definerede trade-offs, hvor valget mellem bestemte fordele og ulemper...... omhyggeligt skal afvejes og balanceres. Det er dog ikke altid hensigtsmæssigt at tænke og træffe beslutninger ud fra sådanne trade-offs. Med udgangspunkt i en kritik af rationalet i trade-off tænkningen illustrerer denne artikel en fremgangsmåde, som kan identificere og efterfølgende udfordre de underliggende...... forudsætninger for et givent trade-off. Artiklen giver herefter tre konkrete eksempler på trade-offs, der kan elimineres via benyttelsen af fremgangsmåden. Det første eksempel vedrører et klassisk logistikproblem, mens de sidste to eksempler er hentet fra økonomistyringsområdet for at illustrere fremgangsmådens...

  9. Reassessing the Trade-Off Hypothesis

    DEFF Research Database (Denmark)

    Rosas, Guillermo; Manzetti, Luigi

    2015-01-01

    Do economic conditions drive voters to punish politicians that tolerate corruption? Previous scholarly work contends that citizens in young democracies support corrupt governments that are capable of promoting good economic outcomes, the so-called trade-off hypothesis. We test this hypothesis bas...

  10. Financing Investment: The Cost Trade-Off

    DEFF Research Database (Denmark)

    Hirth, Stefan; Flor, Christian Riis

    theoretical explanation for the recent empirical findings of Cleary et al. (2007). We split up the endogenously implied financing costs and propose a trade-off between expected liquidation costs and second-best investment costs. For rather unconstrained firms, the risk of costly liquidation dominates the cost...

  11. Arbitrary Hardware Software Trade-Offs

    NARCIS (Netherlands)

    Middelhoek, Peter F.A.

    1995-01-01

    This paper discusses a novel transformation-based design methodology and its use in the design of complex programmable VLSI systems. During the life-cycle of a complex system, the optimal trade-off between partially implementing in hardware or software is changing. This is due to varying system requ

  12. Trading Off Tax Distortion and Tax Evasion

    OpenAIRE

    Wolfram F. Richter; Boadway, Robin

    2001-01-01

    Tax evasion is modeled as a risky activity and integrated into a standard problem of optimal tax design. It is shown that there is a trade off between reducing tax evasion and reducing tax distortion. Thus it is efficient to supplement a broad-based wage tax by a tax on specific consumption if the former is evaded and the latter not. The optimal tax structure can be characterized by an explicit formula.

  13. Generalized railway tank car safety design optimization for hazardous materials transport: Addressing the trade-off between transportation efficiency and safety

    International Nuclear Information System (INIS)

    North America railways offer safe and generally the most economical means of long distance transport of hazardous materials. Nevertheless, in the event of a train accident releases of these materials can pose substantial risk to human health, property or the environment. The majority of railway shipments of hazardous materials are in tank cars. Improving the safety design of these cars to make them more robust in accidents generally increases their weight thereby reducing their capacity and consequent transportation efficiency. This paper presents a generalized tank car safety design optimization model that addresses this tradeoff. The optimization model enables evaluation of each element of tank car safety design, independently and in combination with one another. We present the optimization model by identifying a set of Pareto-optimal solutions for a baseline tank car design in a bicriteria decision problem. This model provides a quantitative framework for a rational decision-making process involving tank car safety design enhancements to reduce the risk of transporting hazardous materials.

  14. Generalized railway tank car safety design optimization for hazardous materials transport: Addressing the trade-off between transportation efficiency and safety

    Energy Technology Data Exchange (ETDEWEB)

    Saat, Mohd Rapik, E-mail: mohdsaat@illinois.edu [Rail Transportation and Engineering Center (RailTEC), Department of Civil and Environmental Engineering, MC-250, University of Illinois at Urbana-Champaign, 1243 Newmark Civil Engineering Laboratory, 205 N. Mathews Ave., Urbana, IL 61801 (United States); Barkan, Christopher P.L. [Rail Transportation and Engineering Center (RailTEC), Department of Civil and Environmental Engineering, MC-250, University of Illinois at Urbana-Champaign, 1243 Newmark Civil Engineering Laboratory, 205 N. Mathews Ave., Urbana, IL 61801 (United States)

    2011-05-15

    North America railways offer safe and generally the most economical means of long distance transport of hazardous materials. Nevertheless, in the event of a train accident releases of these materials can pose substantial risk to human health, property or the environment. The majority of railway shipments of hazardous materials are in tank cars. Improving the safety design of these cars to make them more robust in accidents generally increases their weight thereby reducing their capacity and consequent transportation efficiency. This paper presents a generalized tank car safety design optimization model that addresses this tradeoff. The optimization model enables evaluation of each element of tank car safety design, independently and in combination with one another. We present the optimization model by identifying a set of Pareto-optimal solutions for a baseline tank car design in a bicriteria decision problem. This model provides a quantitative framework for a rational decision-making process involving tank car safety design enhancements to reduce the risk of transporting hazardous materials.

  15. Operational trade-offs in reservoir control

    Science.gov (United States)

    Georgakakos, Aris P.

    1993-11-01

    Reservoir operation decisions require constant reevaluation in the face of conflicting objectives, varying hydrologic conditions, and frequent operational policy changes. Optimality is a relative concept very much dependent on the circumstances under which a decision is made. More than anything else, reservoir management authorities need the means to assess the impacts of various operational options. It is their responsibility to define what is desirable after a thorough evaluation of the existing circumstances. This article presents a model designed to generate operational trade-offs common among reservoir systems. The model avoids an all-encompassing problem formulation and distinguishes three operational modes (levels) corresponding to normal, drought, and flood operations. Each level addresses only relevant system elements and uses a static and a dynamic control module to optimize turbine performance within each planning period and temporally. The model is used for planning the operation of the Savannah River System.

  16. Trade-off analysis of ecosystem services in Eastern Europe

    NARCIS (Netherlands)

    Ruijs, A.; Wossink, Ada; Kortelainen, M.; Alkemade, R.; Schulp, C.J.E.

    2013-01-01

    In this paper we assess trade-offs between ecosystem services in a spatially explicit manner. From a supply side perspective, we estimate opportunity costs, which reflect in monetary terms the trade-offs between ecosystem services due to a marginal land use change. These are based on estimation of t

  17. Conceptualising and managing trade-offs in sustainability assessment

    Energy Technology Data Exchange (ETDEWEB)

    Morrison-Saunders, Angus, E-mail: A.Morrison-Saunders@murdoch.edu.au [School of Geo and Spatial Sciences, North West University (South Africa); School of Environmental Science, Murdoch University (Australia); Pope, Jenny [School of Geo and Spatial Sciences, North West University (South Africa); Integral Sustainability (Australia); Curtin University (Australia)

    2013-01-15

    One of the defining characteristics of sustainability assessment as a form of impact assessment is that it provides a forum for the explicit consideration of the trade-offs that are inherent in complex decision-making processes. Few sustainability assessments have achieved this goal though, and none has considered trade-offs in a holistic fashion throughout the process. Recent contributions such as the Gibson trade-off rules have significantly progressed thinking in this area by suggesting appropriate acceptability criteria for evaluating substantive trade-offs arising from proposed development, as well as process rules for how evaluations of acceptability should occur. However, there has been negligible uptake of these rules in practice. Overall, we argue that there is inadequate consideration of trade-offs, both process and substantive, throughout the sustainability assessment process, and insufficient considerations of how process decisions and compromises influence substantive outcomes. This paper presents a framework for understanding and managing both process and substantive trade-offs within each step of a typical sustainability assessment process. The framework draws together previously published literature and offers case studies that illustrate aspects of the practical application of the framework. The framing and design of sustainability assessment are vitally important, as process compromises or trade-offs can have substantive consequences in terms of sustainability outcomes delivered, with the choice of alternatives considered being a particularly significant determinant of substantive outcomes. The demarcation of acceptable from unacceptable impacts is a key aspect of managing trade-offs. Offsets can be considered as a form of trade-off within a category of sustainability that are utilised to enhance preferred alternatives once conditions of impact acceptability have been met. In this way they may enable net gains to be delivered; another imperative

  18. Conceptualising and managing trade-offs in sustainability assessment

    International Nuclear Information System (INIS)

    One of the defining characteristics of sustainability assessment as a form of impact assessment is that it provides a forum for the explicit consideration of the trade-offs that are inherent in complex decision-making processes. Few sustainability assessments have achieved this goal though, and none has considered trade-offs in a holistic fashion throughout the process. Recent contributions such as the Gibson trade-off rules have significantly progressed thinking in this area by suggesting appropriate acceptability criteria for evaluating substantive trade-offs arising from proposed development, as well as process rules for how evaluations of acceptability should occur. However, there has been negligible uptake of these rules in practice. Overall, we argue that there is inadequate consideration of trade-offs, both process and substantive, throughout the sustainability assessment process, and insufficient considerations of how process decisions and compromises influence substantive outcomes. This paper presents a framework for understanding and managing both process and substantive trade-offs within each step of a typical sustainability assessment process. The framework draws together previously published literature and offers case studies that illustrate aspects of the practical application of the framework. The framing and design of sustainability assessment are vitally important, as process compromises or trade-offs can have substantive consequences in terms of sustainability outcomes delivered, with the choice of alternatives considered being a particularly significant determinant of substantive outcomes. The demarcation of acceptable from unacceptable impacts is a key aspect of managing trade-offs. Offsets can be considered as a form of trade-off within a category of sustainability that are utilised to enhance preferred alternatives once conditions of impact acceptability have been met. In this way they may enable net gains to be delivered; another imperative

  19. Redistribution and the Efficiency-Justice Trade-off

    OpenAIRE

    Petersen, Hans-Georg

    2004-01-01

    Contents: Justice of Needs and Redistribution -The Basics of the Utility Theory -Social Welfare Functions and Redistribution -Utility Possibility Curves on Egoism, Altruism and Envy -Types of Social Welfare Functions The Trade-off Problem Concluding Remarks

  20. Divdends and Equity Prices: The Variance Trade Off

    OpenAIRE

    Margaret Bray; Giovanni Marseguerra

    2002-01-01

    This paper shows that standard corporate finance theory implies that there is potentially a trade off between the variances of dividends and equity prices. We show how the trade off works in a stochastic difference equation model of dividend policy demonstrating that the solution may be unstable for plausible parameter values. At the boundary of the feasible set of price and dividend variances, prices and dividends are perfectly correlated and both follow an AR(1) process. We calculate explic...

  1. Mathematical study of trade-off relations in logistics systems

    Science.gov (United States)

    Nanazawa, Youhei; Suito, Hiroshi; Kawarada, Hideo

    2009-10-01

    This paper presents a mathematical model of trade-off relations arising in third party logistics using Pareto optimal solutions for multi-objective optimization problems. The model defines an optimal set of distribution costs and service levels constituting a trade-off relation. An analogy to the concept of the indifference curve in the field of economics is discussed. Numerical experiments for a simplified problem are performed, demonstrating an increasing process of the utility of logistics.

  2. Trade-offs across Space, Time, and Ecosystem Services

    Directory of Open Access Journals (Sweden)

    Andrew P. Dobson

    2006-06-01

    Full Text Available Ecosystem service (ES trade-offs arise from management choices made by humans, which can change the type, magnitude, and relative mix of services provided by ecosystems. Trade-offs occur when the provision of one ES is reduced as a consequence of increased use of another ES. In some cases, a trade-off may be an explicit choice; but in others, trade-offs arise without premeditation or even awareness that they are taking place. Trade-offs in ES can be classified along three axes: spatial scale, temporal scale, and reversibility. Spatial scale refers to whether the effects of the trade-off are felt locally or at a distant location. Temporal scale refers to whether the effects take place relatively rapidly or slowly. Reversibility expresses the likelihood that the perturbed ES may return to its original state if the perturbation ceases. Across all four Millennium Ecosystem Assessment scenarios and selected case study examples, trade-off decisions show a preference for provisioning, regulating, or cultural services (in that order. Supporting services are more likely to be “taken for granted.” Cultural ES are almost entirely unquantified in scenario modeling; therefore, the calculated model results do not fully capture losses of these services that occur in the scenarios. The quantitative scenario models primarily capture the services that are perceived by society as more important—provisioning and regulating ecosystem services—and thus do not fully capture trade-offs of cultural and supporting services. Successful management policies will be those that incorporate lessons learned from prior decisions into future management actions. Managers should complement their actions with monitoring programs that, in addition to monitoring the short-term provisions of services, also monitor the long-term evolution of slowly changing variables. Policies can then be developed to take into account ES trade-offs at multiple spatial and temporal scales

  3. Life history trade-offs in tropical trees and lianas.

    Science.gov (United States)

    Gilbert, Benjamin; Wright, S Joseph; Muller-Landau, Helene C; Kitajima, Kaoru; Hernandéz, Andrés

    2006-05-01

    It has been hypothesized that tropical trees partition forest light environments through a life history trade-off between juvenile growth and survival; however, the generality of this trade-off across life stages and functional groups has been questioned. We quantified trade-offs between growth and survival for trees and lianas on Barro Colorado Island (BCI), Panama using first-year seedlings of 22 liana and 31 tree species and saplings (10 mm dbh < 39 mm) of 30 tree species. Lianas showed trade-offs similar to those of trees, with both groups exhibiting broadly overlapping ranges in survival and relative growth rates as seedlings. Life history strategies at the seedling stage were highly correlated with those at the sapling stage among tree species, with all species showing an increase in survival with size. Only one of 30 tree species demonstrated a statistically significant ontogenetic shift, having a relatively lower survival rate at the sapling stage than expected. Our results indicate that similar life history trade-offs apply across two functional groups (lianas and trees), and that life history strategies are largely conserved across seedling and sapling life-stages for most tropical tree species. PMID:16761606

  4. Constraints, Trade-offs and the Currency of Fitness.

    Science.gov (United States)

    Acerenza, Luis

    2016-03-01

    Understanding evolutionary trajectories remains a difficult task. This is because natural evolutionary processes are simultaneously affected by various types of constraints acting at the different levels of biological organization. Of particular importance are constraints where correlated changes occur in opposite directions, called trade-offs. Here we review and classify the main evolutionary constraints and trade-offs, operating at all levels of trait hierarchy. Special attention is given to life history trade-offs and the conflict between the survival and reproduction components of fitness. Cellular mechanisms underlying fitness trade-offs are described. At the metabolic level, a linear trade-off between growth and flux variability was found, employing bacterial genome-scale metabolic reconstructions. Its analysis indicates that flux variability can be considered as the currency of fitness. This currency is used for fitness transfer between fitness components during adaptations. Finally, a discussion is made regarding the constraints which limit the increase in the amount of fitness currency during evolution, suggesting that occupancy constraints are probably the main restrictions. PMID:26920684

  5. Constraints, Trade-offs and the Currency of Fitness.

    Science.gov (United States)

    Acerenza, Luis

    2016-03-01

    Understanding evolutionary trajectories remains a difficult task. This is because natural evolutionary processes are simultaneously affected by various types of constraints acting at the different levels of biological organization. Of particular importance are constraints where correlated changes occur in opposite directions, called trade-offs. Here we review and classify the main evolutionary constraints and trade-offs, operating at all levels of trait hierarchy. Special attention is given to life history trade-offs and the conflict between the survival and reproduction components of fitness. Cellular mechanisms underlying fitness trade-offs are described. At the metabolic level, a linear trade-off between growth and flux variability was found, employing bacterial genome-scale metabolic reconstructions. Its analysis indicates that flux variability can be considered as the currency of fitness. This currency is used for fitness transfer between fitness components during adaptations. Finally, a discussion is made regarding the constraints which limit the increase in the amount of fitness currency during evolution, suggesting that occupancy constraints are probably the main restrictions.

  6. Reliability, Risk and Cost Trade-Offs for Composite Designs

    Science.gov (United States)

    Shiao, Michael C.; Singhal, Surendra N.; Chamis, Christos C.

    1996-01-01

    Risk and cost trade-offs have been simulated using a probabilistic method. The probabilistic method accounts for all naturally-occurring uncertainties including those in constituent material properties, fabrication variables, structure geometry and loading conditions. The probability density function of first buckling load for a set of uncertain variables is computed. The probabilistic sensitivity factors of uncertain variables to the first buckling load is calculated. The reliability-based cost for a composite fuselage panel is defined and minimized with respect to requisite design parameters. The optimization is achieved by solving a system of nonlinear algebraic equations whose coefficients are functions of probabilistic sensitivity factors. With optimum design parameters such as the mean and coefficient of variation (representing range of scatter) of uncertain variables, the most efficient and economical manufacturing procedure can be selected. In this paper, optimum values of the requisite design parameters for a predetermined cost due to failure occurrence are computationally determined. The results for the fuselage panel analysis show that the higher the cost due to failure occurrence, the smaller the optimum coefficient of variation of fiber modulus (design parameter) in longitudinal direction.

  7. Quantum trade-off coding for bosonic communication

    CERN Document Server

    Wilde, Mark M; Guha, Saikat

    2011-01-01

    Recent work has precisely characterized the achievable trade-offs between three key information processing tasks---classical communication (generation or consumption), quantum communication (generation or consumption), and shared entanglement (distribution or consumption), measured in bits, qubits, and ebits per channel use respectively. Slices and corner points of this three-dimensional region reduce to several well-known quantum communication protocols over noisy channels. A single trade-off coding technique can attain any point in the region and can outperform time-sharing between the best known protocols for accomplishing each information processing task alone. Previously, the benefits of trade-off coding that had been found were too small to be of much practical value (for the dephasing and the universal cloning machine channels, for instance). In this article, we demonstrate to the contrary that the associated performance gains are remarkably high for several physically relevant bosonic channels that mo...

  8. Time–space trade-offs for longest common extensions

    DEFF Research Database (Denmark)

    Bille, Philip; Gørtz, Inge Li; Sach, Benjamin;

    2014-01-01

    . We study the time–space trade-offs for the problem, that is, the space used for the data structure vs. the worst-case time for answering an LCE query. Let n be the length of T. Given a parameter τ, 1⩽τ⩽n, we show how to achieve either O(n/τ) space and O(τ) query time, or O(n/τ) space and O......(τlog(|LCE(i,j)|/τ)) query time, where |LCE(i,j)| denotes the length of the LCE returned by the query. These bounds provide the first smooth trade-offs for the LCE problem and almost match the previously known bounds at the extremes when τ=1 or τ=n. We apply the result to obtain improved bounds for several applications......-uniform cell probe model showing that our second trade-off is nearly optimal....

  9. Evaluation of trade-offs in costs and environmental impacts for returnable packaging implementation

    Science.gov (United States)

    Jarupan, Lerpong; Kamarthi, Sagar V.; Gupta, Surendra M.

    2004-02-01

    The main thrust of returnable packaging these days is to provide logistical services through transportation and distribution of products and be environmentally friendly. Returnable packaging and reverse logistics concepts have converged to mitigate the adverse effect of packaging materials entering the solid waste stream. Returnable packaging must be designed by considering the trade-offs between costs and environmental impact to satisfy manufacturers and environmentalists alike. The cost of returnable packaging entails such items as materials, manufacturing, collection, storage and disposal. Environmental impacts are explicitly linked with solid waste, air pollution, and water pollution. This paper presents a multi-criteria evaluation technique to assist decision-makers for evaluating the trade-offs in costs and environmental impact during the returnable packaging design process. The proposed evaluation technique involves a combination of multiple objective integer linear programming and analytic hierarchy process. A numerical example is used to illustrate the methodology.

  10. "Entrepreneurship policy: Trade-offs and impact in the EU"

    DEFF Research Database (Denmark)

    Murdock, Karen

    2012-01-01

    Based on the notion that trade-offs in public policies form the basis of the separation of managed and entrepreneurial economies; this paper investigates the impact of policy on actual entrepreneurship activity in these two categories of economies. Using data from 19 European Union member countries......, the impact that policy trade-offs in the goal, target, location and system of finance have on entrepreneurship activity is measured using ordinary least squares regression. The results indicate that while business regulation negatively impact entrepreneurship activity, the location of policy does not show...

  11. Risk-Return Trade-Off for European Stock Markets

    DEFF Research Database (Denmark)

    Aslanidis, Nektarios; Christiansen, Charlotte; Savva, Christos S.

    -order moments as additional measures of risk. The preferred combination of factors varies across countries. In the linear model, there is a strong but negative relation between conditional returns and conditional volatility. A Markov switching model describes the risk-return trade-off well. A number...

  12. Cancer and Longevity-Is There a Trade-off?

    DEFF Research Database (Denmark)

    Christensen, Kaare; Pedersen, Jacob K; Hjelmborg, Jacob V B;

    2012-01-01

    Animal models and a few human studies have suggested a complex interaction between cancer risk and longevity indicating a trade-off where low cancer risk is associated with accelerating aging phenotypes and, vice versa, that longevity potential comes with the cost of increased cancer risk...

  13. Constraints and Freedom of Action: a fitness trade-off

    OpenAIRE

    Massimo Ricottilli

    2006-01-01

    This paper attempts to discuss the role of constraints in network formation and in the exploration process of complex spaces of fitness possiblities. It is held that similarities appear in both social and biological systems. The paper further argues that constraints are instrumental in setting a fitness trade-off between specialised and across-the-board searching.

  14. Trade-Offs between Ecosystem Services in a Mountain Region

    Directory of Open Access Journals (Sweden)

    Simon Briner

    2013-09-01

    Full Text Available Mountain ecosystems provide a broad range of ecosystem services (ES. Trade-offs between different ES are an important aspect in the assessment of future sustainable land-use. Management of ES in mountain regions must confront the challenges of spatial and temporal heterogeneity, and interaction with structural changes in agriculture and forestry. Using a social-ecological modeling framework, we assess the relationships between forest and agricultural ES in a mountain region in Switzerland. Based on the concept of jointness in production, we evaluated trade-offs and synergies among food provision, biodiversity conservation, carbon sequestration, and protection against natural hazards. Results show that increasing the provision of a focal ES in a mountain region may result in alternating trade-offs and synergies, depending on the interaction of economic and technological interdependencies. Thus, management schemes aiming to increase the provision of one focal ES have to consider not only the technological or biological nature of interrelationships, but also the economic interdependencies among different ES. Trade-offs and synergies from these interactions strongly depend on the underlying structural and environmental conditions driven by socioeconomic and climatic developments.

  15. Time-Space Trade-offs for Longest Common Extensions

    DEFF Research Database (Denmark)

    Bille, Philip; Gortz, Inge Li; Sach, Benjamin;

    2012-01-01

    . We study the time-space trade-offs for the problem, that is, the space used for the data structure vs. the worst-case time for answering an LCE query. Let n be the length of T. Given a parameter τ, 1 ≤ τ ≤ n, we show how to achieve either O(n/√τ) space and O(τ) query time, or O(n/τ) space and O(τ log......(|LCE(i,j)|/τ)) query time, where |LCE(i,j)| denotes the length of the LCE returned by the query. These bounds provide the first smooth trade-offs for the LCE problem and almost match the previously known bounds at the extremes when τ = 1 or τ = n. We apply the result to obtain improved bounds for several applications...

  16. Work Fluctuation-Dissipation Trade-Off in Heat Engines.

    Science.gov (United States)

    Funo, Ken; Ueda, Masahito

    2015-12-31

    Reducing work fluctuation and dissipation in heat engines or, more generally, information heat engines that perform feedback control, is vital to maximize their efficiency. The same problem arises when we attempt to maximize the efficiency of a given thermodynamic task that undergoes nonequilibrium processes for arbitrary initial and final states. We find that the most general trade-off relation between work fluctuation and dissipation applicable to arbitrary nonequilibrium processes is bounded from below by the information distance characterizing how far the system is from thermal equilibrium. The minimum amount of dissipation is found to be given in terms of the relative entropy and the Renyi divergence, both of which quantify the information distance between the state of the system and the canonical distribution. We give an explicit protocol that achieves the fundamental lower bound of the trade-off relation.

  17. The trade off between central bank independence and conservativeness

    OpenAIRE

    Eijffinger, S.C.W.; Hoeberichts, M.M.

    1998-01-01

    This paper introduces a parameter for central bank independence in a monetary policy game with a conservative central banker.It tries to explain the optimal degree of central bank independence and conservativeness by four economic and political determinants, both theoretically and empirically.There appears to be a trade off between central bank independence and conservativeness.Then, by comparing the optimal degree of conservativeness and independence with the actual degree of independence, w...

  18. Evolutionary trade-off between weapons and testes

    OpenAIRE

    Simmons, Leigh W.; Emlen, Douglas J.

    2006-01-01

    It has long been recognized that male mating competition is responsible for the evolution of weaponry for mate acquisition. However, when females mate with more than one male, competition between males can continue after mating in the form of sperm competition. Theory predicts that males should increase their investment in sperm production as sperm competition is increased, but it assumes that males face a trade-off between sperm production and other life-history traits such as mate acquisiti...

  19. Modelling the trade-off between profits and principles

    OpenAIRE

    Graafland, J.J.

    2002-01-01

    Corporations discover that social responsibility pays off. However, sometimes doing what is ethical will prove costly to a company. The purpose of this article is to clarify this trade-off by developing an economic model that describes the choice between profits and principles. The model is used to analyse how external factors like a change in consumer interests and competitiveness affect the relationship between profits and principles.

  20. Pathogen life-history trade-offs revealed in allopatry.

    Science.gov (United States)

    Susi, Hanna; Laine, Anna-Liisa

    2013-11-01

    Trade-offs in life-history traits is a central tenet in evolutionary biology, yet their ubiquity and relevance to realized fitness in natural populations remains questioned. Trade-offs in pathogens are of particular interest because they may constrain the evolution and epidemiology of diseases. Here, we studied life-history traits determining transmission in the obligate fungal pathogen, Podosphaera plantaginis, infecting Plantago lanceolata. We find that although traits are positively associated on sympatric host genotypes, on allopatric host genotypes relationships between infectivity and subsequent transmission traits change shape, becoming even negative. The epidemiological prediction of this change in life-history relationships in allopatry is lower disease prevalence in newly established pathogen populations. An analysis of the natural pathogen metapopulation confirms that disease prevalence is lower in newly established pathogen populations and they are more prone to go extinct during winter than older pathogen populations. Hence, life-history trade-offs mediated by pathogen local adaptation may influence epidemiological dynamics at both population and metapopulation levels.

  1. Exploring the psychology of trade-off decision-making in environmental impact assessment

    OpenAIRE

    Retief, Francois; Morrison-Saunders, Angus; Geneletti, Davide; Pope, Jenny

    2013-01-01

    Dealing with trade-offs lies at the heart of environmental impact assessment (EIA). However, there has been scant reflection to date on the concept of trade-offs within the EIA literature. This paper aims to contribute to the thinking about trade-offs by distilling key learning points from research conducted within the field of psychology. In particular, the paper explores three interrelated questions namely: When are trade-off decisions difficult? How do we react when faced with dif...

  2. The cricket and the ant : Organizational trade-offs in changing environments

    NARCIS (Netherlands)

    Peli, Gabor; Bruggeman, Jeroen

    2007-01-01

    Organizations face trade-offs when they adopt strategies in changing resource environments. The type of trade-off depends on the type of resource change. This paper offers an organizational trade-off model for quantitative resource changes. We call it the "Cricket and Ant" (CA) model, because the pe

  3. Performance trade-offs and individual quality in decathletes.

    Science.gov (United States)

    Walker, Jeffrey A; Caddigan, Sean P

    2015-11-01

    Many constraints of organismal design at the cell and organ level, including muscle fiber types, musculoskeletal gearing and control-surface geometry, are believed to cause performance trade-offs at the whole-organism level. Contrary to this expectation, positive correlations between diverse athletic performances are frequently found in vertebrates. Recently, it has been proposed that trade-offs between athletic performances in humans are masked by variation in individual quality and that underlying trade-offs are revealed by adjusting the correlations to 'control' quality. We argue that quality is made up of both intrinsic components, due to the causal mapping between morpho-physiological traits and performance, and extrinsic components, due to variation in training intensity, diet and pathogens. Only the extrinsic component should be controlled. We also show that previous methods to estimate 'quality-free' correlations perform poorly. We show that Wright's factor analysis recovers the correct quality-free correlation matrix and use this method to estimate quality-free correlations among the 10 events of the decathlon using a dataset of male college athletes. We found positive correlations between all decathlon events, which supports an axis that segregates 'good athletes' from 'bad athletes'. Estimates of quality-free correlations are mostly very small (<0.1), suggesting large, quality-free independence between events. Because quality must include both intrinsic and extrinsic components, the physiological significance of these adjusted correlations remains obscure. Regardless, the underlying architecture of the functional systems and the physiological explanation of both the un-adjusted and adjusted correlations remain to be discovered. PMID:26449978

  4. Ant Colonies Do Not Trade-Off Reproduction against Maintenance.

    Science.gov (United States)

    Kramer, Boris H; Schrempf, Alexandra; Scheuerlein, Alexander; Heinze, Jürgen

    2015-01-01

    The question on how individuals allocate resources into maintenance and reproduction is one of the central questions in life history theory. Yet, resource allocation into maintenance on the organismic level can only be measured indirectly. This is different in a social insect colony, a "superorganism" where workers represent the soma and the queen the germ line of the colony. Here, we investigate whether trade-offs exist between maintenance and reproduction on two levels of biological organization, queens and colonies, by following single-queen colonies of the ant Cardiocondyla obscurior throughout the entire lifespan of the queen. Our results show that maintenance and reproduction are positively correlated on the colony level, and we confirm results of an earlier study that found no trade-off on the individual (queen) level. We attribute this unexpected outcome to the existence of a positive feedback loop where investment into maintenance (workers) increases the rate of resource acquisition under laboratory conditions. Even though food was provided ad libitum, variation in productivity among the colonies suggests that resources can only be utilized and invested into additional maintenance and reproduction by the colony if enough workers are available. The resulting relationship between per-capita and colony productivity in our study fits well with other studies conducted in the field, where decreasing per-capita productivity and the leveling off of colony productivity have been linked to density dependent effects due to competition among colonies. This suggests that the absence of trade-offs in our laboratory study might also be prevalent under natural conditions, leading to a positive association of maintenance, (= growth) and reproduction. In this respect, insect colonies resemble indeterminate growing organisms. PMID:26383861

  5. Ant Colonies Do Not Trade-Off Reproduction against Maintenance.

    Directory of Open Access Journals (Sweden)

    Boris H Kramer

    Full Text Available The question on how individuals allocate resources into maintenance and reproduction is one of the central questions in life history theory. Yet, resource allocation into maintenance on the organismic level can only be measured indirectly. This is different in a social insect colony, a "superorganism" where workers represent the soma and the queen the germ line of the colony. Here, we investigate whether trade-offs exist between maintenance and reproduction on two levels of biological organization, queens and colonies, by following single-queen colonies of the ant Cardiocondyla obscurior throughout the entire lifespan of the queen. Our results show that maintenance and reproduction are positively correlated on the colony level, and we confirm results of an earlier study that found no trade-off on the individual (queen level. We attribute this unexpected outcome to the existence of a positive feedback loop where investment into maintenance (workers increases the rate of resource acquisition under laboratory conditions. Even though food was provided ad libitum, variation in productivity among the colonies suggests that resources can only be utilized and invested into additional maintenance and reproduction by the colony if enough workers are available. The resulting relationship between per-capita and colony productivity in our study fits well with other studies conducted in the field, where decreasing per-capita productivity and the leveling off of colony productivity have been linked to density dependent effects due to competition among colonies. This suggests that the absence of trade-offs in our laboratory study might also be prevalent under natural conditions, leading to a positive association of maintenance, (= growth and reproduction. In this respect, insect colonies resemble indeterminate growing organisms.

  6. Ecosystem service trade-offs across global contexts and scales

    Directory of Open Access Journals (Sweden)

    Jeannine Cavender-Bares

    2015-03-01

    Full Text Available Meeting human needs while sustaining the planet's life support systems is the fundamental challenge of our time. What role sustenance of biodiversity and contrasting ecosystem services should play in achieving a sustainable future varies along philosophical, cultural, institutional, societal, and governmental divisions. Contrasting biophysical constraints and perspectives on human well-being arise both within and across countries that span the tropics and temperate zone. Direct sustenance of livelihoods from ecosystem services in East Africa contrasts with the complex and diverse relationships with the land in Mexico and the highly monetary-based economy of the United States. Lack of understanding of the contrasting contexts in which decision-making about trade-offs occurs creates impediments to collective global efforts to sustain the Earth's life support systems. While theoretical notions of the goals of sustainability science seek a unified path forward, realities on the ground present challenges. This Special Feature seeks to provide both an analytical framework and a series of case studies to illuminate impediments posed to sustainability by contrasting biophysical constraints and human perspectives on what should be sustained. The contributors aim to clarify the trade-offs posed to human welfare in sustaining biodiversity and ecosystem services and the challenges in managing for a sustainable future in which human well-being is not compromised as compared to today. Our goal is to provide novel insights on how sustainability can be achieved internationally through exploration of constraints, trade-offs, and human values examined at multiple scales, and across geographic regions from a range of cultural perspectives.

  7. Laser space rendevous and docking trade-off

    Science.gov (United States)

    1974-01-01

    A spaceborne LADAR sensor, which will meet the requirements for rendezvous and docking with a cooperative object in synchronous orbit is presented. The sensor is being configured around a pulsed CO2 laser which can be constructed and deployed using technology which presently exists or is being developed, and which appears to lend itself very well to the envisioned family of space missions. In order to determine the applicability of the type of sensor being considered, the performance of a family of candidate sensors is being traded off as a function of size, weight, and power consumption. The maximum ranges being considered are 50, 100, 200, and 300 nautical miles.

  8. Universality of efficiency at unified trade-off optimization

    Science.gov (United States)

    Zhang, Yanchao; Huang, Chuankun; Lin, Guoxing; Chen, Jincan

    2016-03-01

    We calculate the efficiency at the unified trade-off optimization criterion (the so-called maximum Ω criterion) representing a compromise between the useful energy and the lost energy of heat engines operating between two reservoirs at different temperatures and chemical potentials, and demonstrate that the linear coefficient 3/4 and quadratic coefficient 1/32 of the efficiency at maximum Ω are universal for heat engines under strong coupling and symmetry conditions. It is further proved that the conclusions obtained here also apply to the ecological optimization criterion.

  9. Managing trade-offs makes budgeting processes pay off.

    Science.gov (United States)

    Sorensen, Dean; Sullivan, Denis

    2005-11-01

    Trade-off management is a management system that leverages new technology to enable hospitals to reduce costs while simultaneously delivering exceptional service and quality care. It provides the means to more effectively engage managers in establishing targets that balance what hospitals seek to achieve with what they can afford to spend, while also addressing clinical and operational constraints. It is not a replacement for budgeting, balanced scorecard, or activity-based costing, but rather an approach for integrating them with clinical and operational systems into a more effective management system.

  10. Network Implementation Trade-Offs in Existing Homes

    Science.gov (United States)

    Keiser, Gerd

    2013-03-01

    The ever-increasing demand for networking of high-bandwidth services in existing homes has resulted in several options for implementing an in-home network. Among the options are power-line communication techniques, twisted-pair copper wires, wireless links, and plastic or glass optical fibers. Whereas it is easy to install high-bandwidth optical fibers during the construction of new living units, retrofitting of existing homes with networking capabilities requires some technology innovations. This article addresses some trade-offs that need to be made on what transmission media can be retrofitted most effectively in existing homes.

  11. Universality of efficiency at unified trade-off optimization.

    Science.gov (United States)

    Zhang, Yanchao; Huang, Chuankun; Lin, Guoxing; Chen, Jincan

    2016-03-01

    We calculate the efficiency at the unified trade-off optimization criterion (the so-called maximum Ω criterion) representing a compromise between the useful energy and the lost energy of heat engines operating between two reservoirs at different temperatures and chemical potentials, and demonstrate that the linear coefficient 3/4 and quadratic coefficient 1/32 of the efficiency at maximum Ω are universal for heat engines under strong coupling and symmetry conditions. It is further proved that the conclusions obtained here also apply to the ecological optimization criterion.

  12. Trade-offs in Specific CMOS RF Communication Circuits

    Institute of Scientific and Technical Information of China (English)

    李效龙; 田雨波

    2009-01-01

    The design trade-off in the front-end of the transceiver, such as LNA, mixer, local oscillator and PA, is concerned. The advantages and limitations of the circuit topologies and key parameters of the state-of-the-art CMOS transceiver building blocks are discussed in order to gain more insight about a specific block design. A normalized formula of the figures of merit for each building block is also proposed to evaluate the overall performance of various circuits for fair comparison.

  13. Trade-off study of liquid-metal self-cooled blankets

    International Nuclear Information System (INIS)

    A trade-off study of liquid-metal self-cooled blankets was carried out to define the performance of these blankets with respect to the main functions in a fusion reactor, and to determine the potential to operate at the maximum possible values of the performance parameters. The main purpose is to improve the reactor economics by maximizing the blanket energy multiplication factor, reduce the capital cost of the reactor, and satisfy the design requirements. The main parameters during the course of the study were the tritium breeding ratio (TBR), the blanket energy multiplication factor, the energy fraction lost to the shield, the 6Li enrichment in the breeder material, the total blanket thickness, the reflector material selection, and the compositions of the different blanket zones. Also, the impact of different reactor design choices on the performance parameters was analyzed. The effect of the impurity control system (limiter or divertor), the material choice for the limiter, the elimination of tritium breeding from the inboard section of tokamak reactors, the coolant choice for the nonbreeding inboard blanket, and the neutron source distribution were part of the trade-off study. In addition, tritium breeding benchmark calculations were performed to study the impact of the use of different transport codes and nuclear data libraries. The importance and the negative effect of high TBR on the energy multiplication motivated the benchmark calculations

  14. The trade-off between number and size of offspring in humans and other primates

    OpenAIRE

    Walker, Robert S.; GURVEN, MICHAEL; Burger, Oskar; Hamilton, Marcus J.

    2007-01-01

    Life-history theory posits a fundamental trade-off between number and size of offspring that structures the variability in parental investment across and within species. We investigate this ‘quantity–quality’ trade-off across primates and present evidence that a similar trade-off is also found across natural-fertility human societies. Restating the classic Smith–Fretwell model in terms of allometric scaling of resource supply and offspring investment predicts an inverse scaling relation betwe...

  15. Mechanical Trade-offs in Experimentally Evolved Multicellular Yeast

    Science.gov (United States)

    Jacobeen, Shane; Pentz, Jennifer; Ratcliff, William; Yunker, Peter

    The evolution of multicellularity as much about physics as it is about biology, as selection acts on the physical properties of multicellular bodies. Nascent multicellular organisms are confronted by internal and external forces that act on large length scales and are capable of fracturing intercellular bonds. We study the evolution of the mechanical properties of multicellular `snowflake' yeast that were selected for increased size over ~1,500 generations. While these snowflakes evolve to be larger by mitigating internal forces, they also become more susceptible to fracturing when faced with external compressive forces. Using confocal microscopy and direct mechanical measurements, we investigate the physical underpinnings and consequences of this strength-toughness trade-off.

  16. Defining Pathways and Trade-offs Toward Universal Health Coverage

    Science.gov (United States)

    Verguet, Stéphane

    2016-01-01

    The World Health Organization’s (WHO’s) World Health Report 2010, "Health systems financing, the path to universal coverage," promoted universal health coverage (UHC) as an aspirational objective for country health systems. Yet, in addition to the dimensions of services and coverage, distribution of coverage in the population, and financial risk protection highlighted by the report, the consideration of the budget constraint should be further strengthened in the ensuing debate on resource allocation toward UHC. Beyond the substantial financial constraints faced by low- and middle-income countries, additional considerations, such as the geographical context, the underlying country infrastructure, and the architecture of health systems, determine the feasibility, effectiveness, quality and cost of healthcare delivery. Therefore, increased production and use of local evidence tied to the criteria of health benefits, equity, financial risk protection, and costs accompanying health delivery are needed so that to highlight pathways and acceptable trade-offs toward UHC.

  17. Elastic Fidelity: Trading-off Computational Accuracy for Energy Reduction

    CERN Document Server

    Roy, Sourya; Faisal, S M; Liu, Ke; Hardavellas, Nikos; Parthasarathy, Srinivasan

    2011-01-01

    Power dissipation and energy consumption have become one of the most important problems in the design of processors today. This is especially true in power-constrained environments, such as embedded and mobile computing. While lowering the operational voltage can reduce power consumption, there are limits imposed at design time, beyond which hardware components experience faulty operation. Moreover, the decrease in feature size has led to higher susceptibility to process variations, leading to reliability issues and lowering yield. However, not all computations and all data in a workload need to maintain 100% fidelity. In this paper, we explore the idea of employing functional or storage units that let go the conservative guardbands imposed on the design to guarantee reliable execution. Rather, these units exhibit Elastic Fidelity, by judiciously lowering the voltage to trade-off reliable execution for power consumption based on the error guarantees required by the executing code. By estimating the accuracy r...

  18. Trade-offs underlying maternal breastfeeding decisions: a conceptual model.

    Science.gov (United States)

    Tully, Kristin P; Ball, Helen L

    2013-01-01

    This paper presents a new conceptual model that generates predictions about breastfeeding decisions and identifies interactions that affect outcomes. We offer a contextual approach to infant feeding that models multi-directional influences by expanding on the evolutionary parent-offspring conflict and situation-specific breastfeeding theories. The main hypothesis generated from our framework suggests that simultaneously addressing breastfeeding costs and benefits, in relation to how they are interpreted by mothers, will be most effective. Our approach focuses on contributors to the attitudes and commitment underlying breastfeeding outcomes, beginning in the prenatal period. We conclude that some maternal-offspring conflict is inherent with the dynamic infant feeding relationship. Guidance that anticipates and addresses family trade-offs over time can be incorporated into breastfeeding support for families. PMID:22188564

  19. Synergies and trade-offs in achieving global biodiversity targets.

    Science.gov (United States)

    Di Marco, Moreno; Butchart, Stuart H M; Visconti, Piero; Buchanan, Graeme M; Ficetola, Gentile F; Rondinini, Carlo

    2016-02-01

    After their failure to achieve a significant reduction in the global rate of biodiversity loss by 2010, world governments adopted 20 new ambitious Aichi biodiversity targets to be met by 2020. Efforts to achieve one particular target can contribute to achieving others, but different targets may sometimes require conflicting solutions. Consequently, lack of strategic thinking might result, once again, in a failure to achieve global commitments to biodiversity conservation. We illustrate this dilemma by focusing on Aichi Target 11. This target requires an expansion of terrestrial protected area coverage, which could also contribute to reducing the loss of natural habitats (Target 5), reducing human-induced species decline and extinction (Target 12), and maintaining global carbon stocks (Target 15). We considered the potential impact of expanding protected areas to mitigate global deforestation and the consequences for the distribution of suitable habitat for >10,000 species of forest vertebrates (amphibians, birds, and mammals). We first identified places where deforestation might have the highest impact on remaining forests and then identified places where deforestation might have the highest impact on forest vertebrates (considering aggregate suitable habitat for species). Expanding protected areas toward locations with the highest deforestation rates (Target 5) or the highest potential loss of aggregate species' suitable habitat (Target 12) resulted in partially different protected area network configurations (overlapping with each other by about 73%). Moreover, the latter approach contributed to safeguarding about 30% more global carbon stocks than the former. Further investigation of synergies and trade-offs between targets would shed light on these and other complex interactions, such as the interaction between reducing overexploitation of natural resources (Targets 6, 7), controlling invasive alien species (Target 9), and preventing extinctions of native

  20. Synergies and trade-offs in achieving global biodiversity targets.

    Science.gov (United States)

    Di Marco, Moreno; Butchart, Stuart H M; Visconti, Piero; Buchanan, Graeme M; Ficetola, Gentile F; Rondinini, Carlo

    2016-02-01

    After their failure to achieve a significant reduction in the global rate of biodiversity loss by 2010, world governments adopted 20 new ambitious Aichi biodiversity targets to be met by 2020. Efforts to achieve one particular target can contribute to achieving others, but different targets may sometimes require conflicting solutions. Consequently, lack of strategic thinking might result, once again, in a failure to achieve global commitments to biodiversity conservation. We illustrate this dilemma by focusing on Aichi Target 11. This target requires an expansion of terrestrial protected area coverage, which could also contribute to reducing the loss of natural habitats (Target 5), reducing human-induced species decline and extinction (Target 12), and maintaining global carbon stocks (Target 15). We considered the potential impact of expanding protected areas to mitigate global deforestation and the consequences for the distribution of suitable habitat for >10,000 species of forest vertebrates (amphibians, birds, and mammals). We first identified places where deforestation might have the highest impact on remaining forests and then identified places where deforestation might have the highest impact on forest vertebrates (considering aggregate suitable habitat for species). Expanding protected areas toward locations with the highest deforestation rates (Target 5) or the highest potential loss of aggregate species' suitable habitat (Target 12) resulted in partially different protected area network configurations (overlapping with each other by about 73%). Moreover, the latter approach contributed to safeguarding about 30% more global carbon stocks than the former. Further investigation of synergies and trade-offs between targets would shed light on these and other complex interactions, such as the interaction between reducing overexploitation of natural resources (Targets 6, 7), controlling invasive alien species (Target 9), and preventing extinctions of native

  1. Optimizing time and resource allocation trade-offs for investment into morphological and behavioral defense

    DEFF Research Database (Denmark)

    Steiner, Uli; Pfeiffer, Thomas

    2007-01-01

    Prey organisms are confronted with time and resource allocation trade-offs. Time allocation trade-offs partition time, for example, between foraging effort to acquire resources and behavioral defense. Resource allocation trade-offs partition the acquired resources between multiple traits......, such as growth or morphological defense. We develop a mathematical model for prey organisms that comprise time and resource allocation trade-offs for multiple defense traits. Fitness is determined by growth and survival during ontogeny. We determine optimal defense strategies for environments that differ...

  2. Energy-information trade-offs between movement and sensing.

    Directory of Open Access Journals (Sweden)

    Malcolm A MacIver

    2010-05-01

    Full Text Available While there is accumulating evidence for the importance of the metabolic cost of information in sensory systems, how these costs are traded-off with movement when sensing is closely linked to movement is poorly understood. For example, if an animal needs to search a given amount of space beyond the range of its vision system, is it better to evolve a higher acuity visual system, or evolve a body movement system that can more rapidly move the body over that space? How is this trade-off dependent upon the three-dimensional shape of the field of sensory sensitivity (hereafter, sensorium? How is it dependent upon sensorium mobility, either through rotation of the sensorium via muscles at the base of the sense organ (e.g., eye or pinna muscles or neck rotation, or by whole body movement through space? Here we show that in an aquatic model system, the electric fish, a choice to swim in a more inefficient manner during prey search results in a higher prey encounter rate due to better sensory performance. The increase in prey encounter rate more than counterbalances the additional energy expended in swimming inefficiently. The reduction of swimming efficiency for improved sensing arises because positioning the sensory receptor surface to scan more space per unit time results in an increase in the area of the body pushing through the fluid, increasing wasteful body drag forces. We show that the improvement in sensory performance that occurs with the costly repositioning of the body depends upon having an elongated sensorium shape. Finally, we show that if the fish was able to reorient their sensorium independent of body movement, as fish with movable eyes can, there would be significant energy savings. This provides insight into the ubiquity of sensory organ mobility in animal design. This study exposes important links between the morphology of the sensorium, sensorium mobility, and behavioral strategy for maximally extracting energy from the environment

  3. Energy-information trade-offs between movement and sensing.

    Science.gov (United States)

    MacIver, Malcolm A; Patankar, Neelesh A; Shirgaonkar, Anup A

    2010-05-06

    While there is accumulating evidence for the importance of the metabolic cost of information in sensory systems, how these costs are traded-off with movement when sensing is closely linked to movement is poorly understood. For example, if an animal needs to search a given amount of space beyond the range of its vision system, is it better to evolve a higher acuity visual system, or evolve a body movement system that can more rapidly move the body over that space? How is this trade-off dependent upon the three-dimensional shape of the field of sensory sensitivity (hereafter, sensorium)? How is it dependent upon sensorium mobility, either through rotation of the sensorium via muscles at the base of the sense organ (e.g., eye or pinna muscles) or neck rotation, or by whole body movement through space? Here we show that in an aquatic model system, the electric fish, a choice to swim in a more inefficient manner during prey search results in a higher prey encounter rate due to better sensory performance. The increase in prey encounter rate more than counterbalances the additional energy expended in swimming inefficiently. The reduction of swimming efficiency for improved sensing arises because positioning the sensory receptor surface to scan more space per unit time results in an increase in the area of the body pushing through the fluid, increasing wasteful body drag forces. We show that the improvement in sensory performance that occurs with the costly repositioning of the body depends upon having an elongated sensorium shape. Finally, we show that if the fish was able to reorient their sensorium independent of body movement, as fish with movable eyes can, there would be significant energy savings. This provides insight into the ubiquity of sensory organ mobility in animal design. This study exposes important links between the morphology of the sensorium, sensorium mobility, and behavioral strategy for maximally extracting energy from the environment. An

  4. Strong selection genome-wide enhances fitness trade-offs across environments and episodes of selection.

    Science.gov (United States)

    Anderson, Jill T; Lee, Cheng-Ruei; Mitchell-Olds, Thomas

    2014-01-01

    Fitness trade-offs across episodes of selection and environments influence life-history evolution and adaptive population divergence. Documenting these trade-offs remains challenging as selection can vary in magnitude and direction through time and space. Here, we evaluate fitness trade-offs at the levels of the whole organism and the quantitative trait locus (QTL) in a multiyear field study of Boechera stricta (Brassicaceae), a genetically tractable mustard native to the Rocky Mountains. Reciprocal local adaptation was pronounced for viability, but not for reproductive components of fitness. Instead, local genomes had a fecundity advantage only in the high latitude garden. By estimating realized selection coefficients from individual-level data on viability and reproductive success and permuting the data to infer significance, we examined the genetic basis of fitness trade-offs. This analytical approach (Conditional Neutrality-Antagonistic Pleiotropy, CNAP) identified genetic trade-offs at a flowering phenology QTL (costs of adaptation) and revealed genetic trade-offs across fitness components (costs of reproduction). These patterns would not have emerged from traditional ANOVA-based QTL mapping. Our analytical framework can be applied to other systems to investigate fitness trade-offs. This task is becoming increasingly important as climate change may alter fitness landscapes, potentially disrupting fitness trade-offs that took many generations to evolve. PMID:24102539

  5. Speed-accuracy trade-off behavior: Response caution adjustment or mixing task strategies?

    NARCIS (Netherlands)

    L. van Maanen

    2015-01-01

    The speed-accuracy trade-off (SAT) effect refers to the behavioral trade-off between fast yet error-prone responses and accurate but slow responses. Multiple theories on the cognitive mechanisms behind SAT exist. One theory assumes that SAT is a consequence of strategically adjusting the amount of e

  6. Is there evidence for a mixture of processes in speed-accuracy trade-off behavior?

    NARCIS (Netherlands)

    L. van Maanen

    2016-01-01

    The speed-accuracy trade-off (SAT) effect refers to the behavioral trade-off between fast yet error-prone respones and accurate but slow responses. Multiple theories on the cognitive mechanisms behind SAT exist. One theory assumes that SAT is a consequence of strategically adjusting the amount of ev

  7. Trade-offs between chemical defence and regrowth capacity in Plantago lanceolata

    NARCIS (Netherlands)

    Reudler, J.H.; Honders, S.C.; Turin, H.; Biere, A.

    2013-01-01

    Resistance and tolerance are different strategies of plants to deal with herbivore attack. Since resources are limited and resistance and tolerance serve similar functions for plants, trade-offs between these two strategies have often been postulated. In this study we investigated trade-offs between

  8. Investigating the trade-offs of microwave susceptors in energetic composites: Microwave heating versus combustion performance

    Science.gov (United States)

    Crane, C. A.; Pantoya, M. L.; Weeks, B. L.

    2014-03-01

    Recently, microwave technology has been used to ignite energetic materials when studies showed that metal powders readily absorb microwave energy. This study investigates adding a graphite susceptor to an energetic composite consisting of aluminum (Al) and iron (III) oxide (Fe2O3) and examines microwave coupling to the sample. In a companion study, the combustion of this thermite as a function of susceptor concentration was also studied to evaluate the trade-off between enhancing microwave coupling and flame propagation speed. Results show that graphite enhances microwave coupling up to 10% by mass concentration but reduces heating at higher percentages that exceed a percolation threshold. As susceptor concentrations increased greater than one mass percent, the flame propagation speed correspondingly decreased.

  9. Zooplankton competition promotes trade-offs affecting diapause in rotifers.

    Science.gov (United States)

    Aránguiz-Acuña, Adriana; Ramos-Jiliberto, Rodrigo; Serra, Manuel

    2015-01-01

    Facultative diapause should be favoured by natural selection in temporary variable habitats. Diapause patterns are evolutionary constrained because producing diapause is resource demanding, which might have implications for competitive dynamics and competitor coexistence through mechanisms such as the storage effect. Besides these implications, competition intensity might affect the quality of the diapausing stages and the reproductive success of the offspring emerging from them. We experimentally analysed traits involved in diapause in the cyclically parthenogenetic rotifer Brachionus calyciflorus, in relation to the presence of its competitor, the cladoceran Moina micrura. Under competition with Moina, Brachionus produced fewer diapausing eggs, most of which possessed visual attributes indicating a higher quality. These diapausing eggs produced under a competitive environment had a higher hatching success; however, the hatchlings exhibited a lower population growth rate. We propose the existence of trade-offs between traits related to diapause: the number of produced eggs, quality of these eggs and hatchling performance. Our results show that interspecific competition may cause fine-tuned changes in the life cycle patterns of the populations. Furthermore, these changes could affect that abundance and performance of competitors and thereby drive back effects on the competitive output. These diapause-driven feedback mechanisms may have strong implications for the dynamics of the natural communities. PMID:25464990

  10. Fitness Trade-Offs in Competence Differentiation of Bacillus subtilis

    Science.gov (United States)

    Yüksel, Melih; Power, Jeffrey J.; Ribbe, Jan; Volkmann, Thorsten; Maier, Berenike

    2016-01-01

    In the stationary phase, Bacillus subtilis differentiates stochastically and transiently into the state of competence for transformation (K-state). The latter is associated with growth arrest, and it is unclear how the ability to develop competence is stably maintained, despite its cost. To quantify the effect differentiation has on the competitive fitness of B. subtilis, we characterized the competition dynamics between strains with different probabilities of entering the K-state. The relative fitness decreased with increasing differentiation probability both during the stationary phase and during outgrowth. When exposed to antibiotics inhibiting cell wall synthesis, transcription, and translation, cells that differentiated into the K-state showed a selective advantage compared to differentiation-deficient bacteria; this benefit did not require transformation. Although beneficial, the K-state was not induced by sub-MIC concentrations of antibiotics. Increasing the differentiation probability beyond the wt level did not significantly affect the competition dynamics with transient antibiotic exposure. We conclude that the competition dynamics are very sensitive to the fraction of competent cells under benign conditions but less sensitive during antibiotic exposure, supporting the picture of stochastic differentiation as a fitness trade-off. PMID:27375604

  11. Cadmium Protection Strategies—A Hidden Trade-Off?

    Science.gov (United States)

    Sandbichler, Adolf Michael; Höckner, Martina

    2016-01-01

    Cadmium (Cd) is a non-essential transition metal which is introduced into the biosphere by various anthropogenic activities. Environmental pollution with Cd poses a major health risk and Cd toxicity has been extensively researched over the past decades. This review aims at changing the perspective by discussing protection mechanisms available to counteract a Cd insult. Antioxidants, induction of antioxidant enzymes, and complexation of Cd to glutathione (GSH) and metallothionein (MT) are the most potent protective measures to cope with Cd-induced oxidative stress. Furthermore, protection mechanisms include prevention of endoplasmic reticulum (ER) stress, mitophagy and metabolic stress, as well as expression of chaperones. Pre-exposure to Cd itself, or co-exposure to other metals or trace elements can improve viability under Cd exposure and cells have means to reduce Cd uptake and improve Cd removal. Finally, environmental factors have negative or positive effects on Cd toxicity. Most protection mechanisms aim at preventing cellular damage. However, this might not be possible without trade-offs like an increased risk of carcinogenesis. PMID:26805823

  12. Telomere Length and the Cancer–Atherosclerosis Trade-Off

    Science.gov (United States)

    Stone, Rivka C.; Horvath, Kent; Kark, Jeremy D.; Susser, Ezra; Tishkoff, Sarah A.; Aviv, Abraham

    2016-01-01

    Modern humans, the longest-living terrestrial mammals, display short telomeres and repressed telomerase activity in somatic tissues compared with most short-living small mammals. The dual trait of short telomeres and repressed telomerase might render humans relatively resistant to cancer compared with short-living small mammals. However, the trade-off for cancer resistance is ostensibly increased age-related degenerative diseases, principally in the form of atherosclerosis. In this communication, we discuss (a) the genetics of human telomere length, a highly heritable complex trait that is influenced by genetic ancestry, sex, and paternal age at conception, (b) how cancer might have played a role in the evolution of telomere biology across mammals, (c) evidence that in modern humans telomere length is a determinant (rather than only a biomarker) of cancer and atherosclerosis, and (d) the potential influence of relatively recent evolutionary forces in fashioning the variation in telomere length across and within populations, and their likely lasting impact on major diseases in humans. Finally, we propose venues for future research on human telomere genetics in the context of its potential role in shaping the modern human lifespan. PMID:27386863

  13. Cadmium Protection Strategies—A Hidden Trade-Off?

    Directory of Open Access Journals (Sweden)

    Adolf Michael Sandbichler

    2016-01-01

    Full Text Available Cadmium (Cd is a non-essential transition metal which is introduced into the biosphere by various anthropogenic activities. Environmental pollution with Cd poses a major health risk and Cd toxicity has been extensively researched over the past decades. This review aims at changing the perspective by discussing protection mechanisms available to counteract a Cd insult. Antioxidants, induction of antioxidant enzymes, and complexation of Cd to glutathione (GSH and metallothionein (MT are the most potent protective measures to cope with Cd-induced oxidative stress. Furthermore, protection mechanisms include prevention of endoplasmic reticulum (ER stress, mitophagy and metabolic stress, as well as expression of chaperones. Pre-exposure to Cd itself, or co-exposure to other metals or trace elements can improve viability under Cd exposure and cells have means to reduce Cd uptake and improve Cd removal. Finally, environmental factors have negative or positive effects on Cd toxicity. Most protection mechanisms aim at preventing cellular damage. However, this might not be possible without trade-offs like an increased risk of carcinogenesis.

  14. Trade-Offs in Delayed Information Transmission in Biochemical Networks

    Science.gov (United States)

    Mancini, F.; Marsili, M.; Walczak, A. M.

    2016-03-01

    In order to transmit biochemical signals, biological regulatory systems dissipate energy with concomitant entropy production. Additionally, signaling often takes place in challenging environmental conditions. In a simple model regulatory circuit given by an input and a delayed output, we explore the trade-offs between information transmission and the system's energetic efficiency. We determine the maximally informative network, given a fixed amount of entropy production and a delayed response, exploring both the case with and without feedback. We find that feedback allows the circuit to overcome energy constraints and transmit close to the maximum available information even in the dissipationless limit. Negative feedback loops, characteristic of shock responses, are optimal at high dissipation. Close to equilibrium positive feedback loops, known for their stability, become more informative. Asking how the signaling network should be constructed to best function in the worst possible environment, rather than an optimally tuned one or in steady state, we discover that at large dissipation the same universal motif is optimal in all of these conditions.

  15. Telomere Length and the Cancer-Atherosclerosis Trade-Off.

    Science.gov (United States)

    Stone, Rivka C; Horvath, Kent; Kark, Jeremy D; Susser, Ezra; Tishkoff, Sarah A; Aviv, Abraham

    2016-07-01

    Modern humans, the longest-living terrestrial mammals, display short telomeres and repressed telomerase activity in somatic tissues compared with most short-living small mammals. The dual trait of short telomeres and repressed telomerase might render humans relatively resistant to cancer compared with short-living small mammals. However, the trade-off for cancer resistance is ostensibly increased age-related degenerative diseases, principally in the form of atherosclerosis. In this communication, we discuss (a) the genetics of human telomere length, a highly heritable complex trait that is influenced by genetic ancestry, sex, and paternal age at conception, (b) how cancer might have played a role in the evolution of telomere biology across mammals, (c) evidence that in modern humans telomere length is a determinant (rather than only a biomarker) of cancer and atherosclerosis, and (d) the potential influence of relatively recent evolutionary forces in fashioning the variation in telomere length across and within populations, and their likely lasting impact on major diseases in humans. Finally, we propose venues for future research on human telomere genetics in the context of its potential role in shaping the modern human lifespan. PMID:27386863

  16. Fitness Trade-Offs in Competence Differentiation of Bacillus subtilis.

    Science.gov (United States)

    Yüksel, Melih; Power, Jeffrey J; Ribbe, Jan; Volkmann, Thorsten; Maier, Berenike

    2016-01-01

    In the stationary phase, Bacillus subtilis differentiates stochastically and transiently into the state of competence for transformation (K-state). The latter is associated with growth arrest, and it is unclear how the ability to develop competence is stably maintained, despite its cost. To quantify the effect differentiation has on the competitive fitness of B. subtilis, we characterized the competition dynamics between strains with different probabilities of entering the K-state. The relative fitness decreased with increasing differentiation probability both during the stationary phase and during outgrowth. When exposed to antibiotics inhibiting cell wall synthesis, transcription, and translation, cells that differentiated into the K-state showed a selective advantage compared to differentiation-deficient bacteria; this benefit did not require transformation. Although beneficial, the K-state was not induced by sub-MIC concentrations of antibiotics. Increasing the differentiation probability beyond the wt level did not significantly affect the competition dynamics with transient antibiotic exposure. We conclude that the competition dynamics are very sensitive to the fraction of competent cells under benign conditions but less sensitive during antibiotic exposure, supporting the picture of stochastic differentiation as a fitness trade-off. PMID:27375604

  17. Fitness trade-offs in competence differentiation of Bacillus subtilis

    Directory of Open Access Journals (Sweden)

    Melih Yüksel

    2016-06-01

    Full Text Available In the stationary phase, Bacillus subtilis differentiates stochastically and transiently into the state of competence for transformation (K-state. The latter is associated with growth arrest, and it is unclear how the ability to develop competence is stably maintained, despite its cost. To quantify the effect differentiation has on the competitive fitness of B. subtilis, we characterized the competition dynamics between strains with different probabilities of entering the K-state. The relative fitness decreased with increasing differentiation probability both during the stationary phase and during outgrowth. When exposed to antibiotics inhibiting cell wall synthesis, transcription, and translation, cells that differentiated into the K-state showed a selective advantage compared to differentiation-deficient bacteria; this benefit did not require transformation. Although beneficial, the K-state was not induced by sub-MIC concentrations of antibiotics. Increasing the differentiation probability beyond the wt level did not significantly affect the competition dynamics with transient antibiotic exposure. We conclude that the competition dynamics are very sensitive to the fraction of competent cells under benign conditions but less sensitive during antibiotic exposure, supporting the picture of stochastic differentiation as a fitness trade-off.

  18. Anthrax Sampling and Decontamination: Technology Trade-Offs

    Energy Technology Data Exchange (ETDEWEB)

    Price, Phillip N.; Hamachi, Kristina; McWilliams, Jennifer; Sohn, Michael D.

    2008-09-12

    The goal of this project was to answer the following questions concerning response to a future anthrax release (or suspected release) in a building: 1. Based on past experience, what rules of thumb can be determined concerning: (a) the amount of sampling that may be needed to determine the extent of contamination within a given building; (b) what portions of a building should be sampled; (c) the cost per square foot to decontaminate a given type of building using a given method; (d) the time required to prepare for, and perform, decontamination; (e) the effectiveness of a given decontamination method in a given type of building? 2. Based on past experience, what resources will be spent on evaluating the extent of contamination, performing decontamination, and assessing the effectiveness of the decontamination in abuilding of a given type and size? 3. What are the trade-offs between cost, time, and effectiveness for the various sampling plans, sampling methods, and decontamination methods that have been used in the past?

  19. Acknowledging Trade-offs and Understanding Complexity: Exurbanization Issues in Macon County, North Carolina

    Directory of Open Access Journals (Sweden)

    Richard A. Vercoe

    2014-03-01

    Full Text Available We applied an integrative framework to illuminate and discuss the complexities of exurbanization in Macon County, North Carolina. The case of Macon County, North Carolina, highlights the complexity involved in addressing issues of exurbanization in the Southern Appalachian region. Exurbanization, the process by which urban residents move into rural areas in search of unique natural amenities and idealized lifestyles, can often have a dramatic impact on the local economy, culture, and environment. Within Macon County, complex debates and tensions among multiple stakeholders struggle to address local residential development. How can better problem definition benefit rural communities in addressing exurbanization pressures and effects? We asserted that a key factor in the shortcomings of previous solutions was the shortsightedness inherent in policy that attempts to treat individual symptoms without being able to adequately characterize the underlying problem. The goal of the integrative framework is to initiate an iterative process of transparent negotiation, which recognizes a range of potential choices to be considered and to embrace the social complexities that can at times overwhelm scholars and practitioners, inviting simplification and polarization of the issues. This new and emerging framework offers a novel way of approaching conservation and development issues where other frameworks have failed. It helps acknowledge the difficult choices, i.e., trade-offs, that have to be made in a material process like exurbanization. Trade-offs will be necessary in any negotiation related to conservation. Therefore, conflict surrounding specific values, e.g., cultural, financial, or ecological, must be acknowledged upfront to move deeper into issues of plurality. Given the complexity, understanding how the process of exurbanization is being played out within Macon County provided not only an opportunity to demonstrate the functionality of an integrative

  20. Plasticity as panacea? Nerves, hormones, and the currencies of trade-offs

    Institute of Scientific and Technical Information of China (English)

    Elizabeth BASTIAANS; Elizabeth SWANGER

    2015-01-01

    Phenotypic plasticity is nearly universal among organisms,and evidence indicates that plasticity can exhibit additive genetic variation and respond to selection.These findings have important implications for our understanding of how plasticity may be constrained and how its mechanistic structure may affect its evolution.Many life history trade-offs may be conceptualized as plastic traits,with individuals varying in their position along trade-off axes due to genetic differences,developmental plasticity,or short-term plasticity occurring throughout an individual's lifetime.Behavioral plasticity is key to understanding when organisms are likely to encounter trade-offs,whether those trade-offs can be mitigated,and how the trade-offs affect the ecology and evolution of populations.In this review,we discuss hormonal and neural mechanisms that may influence how plastic behavioral traits are expressed and evolve.We also outline a classification of life history trade-offs and their mechanistic bases and discuss the currencies most likely to mediate each category of trade-off and how they are tied to the mechanisms by which animals express their behaviors [Current Zoology 61 (2):251-264,2015].

  1. Trade-offs between better hearing and better cosmetics.

    Science.gov (United States)

    Tyler, Richard S; Witt, Shelley A; Dunn, Camille C

    2004-12-01

    A case study is reported of an adult bilateral cochlear implant patient who owns both a pair of ear-level and body-worn speech processors and chooses to wear them in unique configurations, knowingly compromising his auditory performance. The aim was to determine if differences in hearing could be quantified between these devices and to examine the size of these effects that would lend themselves to trading between performance and cosmetics. The patient reported wearing bilateral ear-level speech processors (programmed with the Cochlear Corporation spectral PEAK [SPEAK] coding strategy) 75% of the time for cosmetic and convenience reasons even though he "heard the best" with bilateral body-worn speech processors (programmed with the Cochlear Corporation advanced combination encoder strategy [ACE]). Speech perception and localization tests confirmed that this patient performed significantly better on monosyllabic phonemes in quiet (a difference from 60% to 75%) and localization (a total root-mean-squared-error difference from 22 degrees to 12degrees ) with bilateral body-worn speech processors and consistently rated various speech sounds as more clear than with bilateral ear-level units. There was a 2-dB difference in sentence reception threshold in noise, which was not statistically significant. These results suggest that clinicians should consider and provide options to patients when there are trade-offs to be made regarding understanding performance and cosmetics. Some individuals may choose better speech perception over cosmetics, and the ability to choose might result in greater compliance. The observations made here are relevant to hearing aid users as well. PMID:15903145

  2. Area Versus Speed Trade-off Analysis of a WiMAX Deinterleaver Circuit Design

    OpenAIRE

    Rafique, Omar

    2014-01-01

    Trade-off is one of the main design parameters in the field of electronic circuit design. Whereas smaller electronics devices which use less hardware due to techniques like hardware multiplexing or due to smaller devices created due to techniques developed by nanotechnology and MEMS, are more appealing, a trade-off between area, power and speed is inevitable. This paper analyses the trade-off in the design of WiMAX deinterleaver. The main aim is to reduce the hardware utilization in a deinter...

  3. Evolution of Acute Infections and the Invasion-Persistence Trade-Off

    OpenAIRE

    King, Aaron A.; Shrestha, Sourya; Harvill, Eric T.; Bjørnstad, Ottar N.

    2009-01-01

    We seek to understand the conditions favoring the evolution of acute, highly transmissible infections. Most work on the life-history evolution of pathogens has focused on the transmission-virulence trade-off. Here we focus on a distinct trade-off that operates, even among avirulent pathogens, between a pathogen’s speed of invasion and its ability to persist in a finite host population. Other authors have shown how this invasion-persistence trade-off can lead to intermediate pathogen attack ra...

  4. Evidence of the Trade-Off between Starvation and Predation Risks in Ducks.

    OpenAIRE

    Cédric Zimmer; Mathieu Boos; Nicolas Poulin; Andrew Gosler; Odile Petit; Jean-Patrice Robin

    2011-01-01

    The theory of trade-off between starvation and predation risks predicts a decrease in body mass in order to improve flight performance when facing high predation risk. To date, this trade-off has mainly been validated in passerines, birds that store limited body reserves for short-term use. In the largest avian species in which the trade-off has been investigated (the mallard, Anas platyrhynchos), the slope of the relationship between mass and flight performance was steeper in proportion to l...

  5. Trade-off preferences regarding adjuvant endocrine therapy among women with estrogen receptor-positive breast cancer

    NARCIS (Netherlands)

    Wouters, H; Maatman, G A; Van Dijk, L; Bouvy, M L; Vree, R; Van Geffen, E C G; Nortier, J W; Stiggelbout, A M

    2013-01-01

    BACKGROUND: There is substantial nonadherence to effective adjuvant endocrine therapy for breast cancer prevention. We therefore examined patients' trade-offs between the efficacy, side-effects, and regimen duration, and whether trade-offs predicted nonadherence. PATIENTS AND METHODS: Trade-offs fro

  6. Functional trade-offs increase species diversity in experimental plant communities.

    Science.gov (United States)

    Ben-Hur, Eyal; Fragman-Sapir, Ori; Hadas, Rivka; Singer, Alon; Kadmon, Ronen

    2012-11-01

    Functional trade-offs have long been recognised as important mechanisms of species coexistence, but direct experimental evidence for such mechanisms is extremely rare. Here, we test the effect of one classical trade-off - a negative correlation between seed size and seed number - by establishing microcosm plant communities with positive, negative and no correlation between seed size and seed number and analysing the effect of the seed size/number correlation on species richness. Consistent with theory, a negative correlation between seed size and seed number led to a higher number of species in the communities and a corresponding wider range of seed size (a measure of functional richness) by promoting coexistence of large- and small-seeded species. Our study provides the first direct evidence that a seed size/number trade-off may contribute to species coexistence, and at a wider context, demonstrates the potential role of functional trade-offs in maintaining species diversity.

  7. Speed-accuracy trade-off behavior: Response caution adjustment or mixing task strategies?

    OpenAIRE

    Maanen, van, L.

    2015-01-01

    The speed-accuracy trade-off (SAT) effect refers to the behavioral trade-off between fast yet error-prone responses and accurate but slow responses. Multiple theories on the cognitive mechanisms behind SAT exist. One theory assumes that SAT is a consequence of strategically adjusting the amount of evidence required for overt behaviors, such as perceptual choices. Another theory hypothesizes that SAT is the consequence of mixing different task strategies. In this paper these theories are disam...

  8. Many-objective optimization and visual analytics reveal key trade-offs for London's water supply

    OpenAIRE

    Matrosov, E. S.; Huskova, I.; Kasprzyk, J. R.; J. J. Harou; Lambert, C; Reed, P. M.

    2015-01-01

    In this study, we link a water resource management simulator to multi-objective search to reveal the key trade-offs inherent in planning a real-world water resource system. We consider new supplies and demand management (conservation) options while seeking to elucidate the trade-offs between the best portfolios of schemes to satisfy projected water demands. Alternative system designs are evaluated using performance measures that minimize capital and operating costs and energy use while maximi...

  9. Evolution of fitness trade-offs in locally adapted populations of Pseudomonas fluorescens

    DEFF Research Database (Denmark)

    Schick, Alana; Bailey, Susan; Kassen, Rees

    2015-01-01

    characterize the genetic causes of trade-offs generating local adaptation in populations of Pseudomonas fluorescens that had previously been evolved for specialization on three different carbon resources. We measured the fitness effects of mutations that arose during selection in that environment...... provide a detailed account of the genetics of specialization and suggest that the evolution of trade-offs associated with local adaptation may often result from the antagonistic effects of beneficial mutations substituted later in adaptation....

  10. Testing the predective validity of the time trade-off and the Stardard Gamble

    OpenAIRE

    Jose María Abellán-Perpiñán; Han Bleichrodt; Jose Luis Pinto-Prades

    2007-01-01

    This paper tests the consistency of health utility measurements with individual preferences. We compare three methods, the time trade-off, the standard gamble and a version of the standard gamble that corrects for the deviations from expected utility modelled by prospect theory. Individual preferences are measured both through a ranking task and through a choice task. In decisions involving no risk the time trade-off is most consistent with people’s preferences with the standard gamble a clos...

  11. Testing the Predictive Validity of the Time Trade-Off and the Standard Gamble.

    OpenAIRE

    JOSE MARIA ABELLAN-PERPIÑAN; Han Bleichrodt; Jose Luis Pinto-Prades

    2007-01-01

    This paper tests the consistency of health utility measurements with individual preferences. We compare three methods, the time trade-off, the standard gamble and a version of the standard gamble that corrects for the deviations from expected utility modeled by prospect theory. Individual preferences are measured both through a ranking task and through a choice task. In decisions involving no risk the time trade-off is most consistent with people’s preferences with the standard gamble a close...

  12. Trade-off between age of first reproduction and survival in a female primate

    OpenAIRE

    Blomquist, Gregory E.

    2009-01-01

    Trade-offs are central to life-history theory but difficult to document. Patterns of phenotypic and genetic correlations in rhesus macaques, Macaca mulatta—a long-lived, slow-reproducing primate—are used to test for a trade-off between female age of first reproduction and adult survival. A strong positive genetic correlation indicates that female macaques suffer reduced adult survival when they mature relatively early and implies primate senescence can be explained, in part, by antagonistic p...

  13. Beyond size–number trade-offs: clutch size as a maternal effect

    OpenAIRE

    Brown, Gregory P.; Shine, Richard

    2009-01-01

    Traditionally, research on life-history traits has viewed the link between clutch size and offspring size as a straightforward linear trade-off; the product of these two components is taken as a measure of maternal reproductive output. Investing more per egg results in fewer but larger eggs and, hence, offspring. This simple size–number trade-off has proved attractive to modellers, but our experimental studies on keelback snakes (Tropidonophis mairii, Colubridae) reveal a more complex relatio...

  14. The offspring quantity-quality trade-off and human fertility variation.

    OpenAIRE

    Lawson, DW; Borgerhoff Mulder, M

    2016-01-01

    The idea that trade-offs between offspring quantity and quality shape reproductive behaviour has long been central to economic perspectives on fertility. It also has a parallel and richer theoretical foundation in evolutionary ecology. We review the application of the quantity-quality trade-off concept to human reproduction, emphasizing distinctions between clutch size and lifetime fertility, and the wider set of forces contributing to fertility variation in iteroparous and sexually reproduci...

  15. Experimental selection reveals a trade-off between fecundity and lifespan in the coliphage Qß

    OpenAIRE

    García-Villada, Libertad; Drake, John W.

    2013-01-01

    Understanding virus evolution is key for improving ways to counteract virus-borne diseases. Results from comparative analyses have previously suggested a trade-off between fecundity and lifespan for viruses that infect the bacterium Escherichia coli (i.e. for coliphages), which, if confirmed, would define a particular constraint on the evolution of virus fecundity. Here, the occurrence of such a trade-off is investigated through a selection experiment using the coliphage Qß. Selection was app...

  16. Outcrossing, mitotic recombination, and life-history trade-offs shape genome evolution in Saccharomyces cerevisiae

    OpenAIRE

    Magwene, Paul M.; Kayıkçı, Ömür; Granek, Joshua A.; Reininga, Jennifer M.; Scholl, Zackary; Murray, Debra

    2011-01-01

    We carried out a population genomic survey of Saccharomyces cerevisiae diploid isolates and find that many budding yeast strains have high levels of genomic heterozygosity, much of which is likely due to outcrossing. We demonstrate that variation in heterozygosity among strains is correlated with a life-history trade-off that involves how readily yeast switch from asexual to sexual reproduction under nutrient stress. This trade-off is reflected in a negative relationship between sporulation e...

  17. The life-history trade-off between fertility and child survival.

    OpenAIRE

    Lawson, D. W.; Alvergne, A.; Gibson, M A

    2012-01-01

    Evolutionary models of human reproduction argue that variation in fertility can be understood as the local optimization of a life-history trade-off between offspring quantity and ‘quality’. Child survival is a fundamental dimension of quality in these models as early-life mortality represents a crucial selective bottleneck in human evolution. This perspective is well-rehearsed, but current literature presents mixed evidence for a trade-off between fertility and child survival, and little empi...

  18. Construct validity of the interview Time Trade-Off and computer Time Trade-Off in patients with rheumatoid arthritis: A cross-sectional observational pilot study

    NARCIS (Netherlands)

    Buitinga, Laurien; Braakman-Jansen, Louise M.A.; Taal, Erik; Laar, van de Mart A.F.J.

    2012-01-01

    Background The Time Trade-Off (TTO) is a widely used instrument for valuing preference-based health-related quality of life (HRQoL). The TTO reveals preferences for own current health (‘utilities’) on a scale anchored between death (0) and perfect health (1). Limited information on the external vali

  19. Dopaminergic Control of the Exploration-Exploitation Trade-Off via the Basal Ganglia

    Science.gov (United States)

    Humphries, Mark D.; Khamassi, Mehdi; Gurney, Kevin

    2012-01-01

    We continuously face the dilemma of choosing between actions that gather new information or actions that exploit existing knowledge. This “exploration-exploitation” trade-off depends on the environment: stability favors exploiting knowledge to maximize gains; volatility favors exploring new options and discovering new outcomes. Here we set out to reconcile recent evidence for dopamine’s involvement in the exploration-exploitation trade-off with the existing evidence for basal ganglia control of action selection, by testing the hypothesis that tonic dopamine in the striatum, the basal ganglia’s input nucleus, sets the current exploration-exploitation trade-off. We first advance the idea of interpreting the basal ganglia output as a probability distribution function for action selection. Using computational models of the full basal ganglia circuit, we showed that, under this interpretation, the actions of dopamine within the striatum change the basal ganglia’s output to favor the level of exploration or exploitation encoded in the probability distribution. We also found that our models predict striatal dopamine controls the exploration-exploitation trade-off if we instead read-out the probability distribution from the target nuclei of the basal ganglia, where their inhibitory input shapes the cortical input to these nuclei. Finally, by integrating the basal ganglia within a reinforcement learning model, we showed how dopamine’s effect on the exploration-exploitation trade-off could be measurable in a forced two-choice task. These simulations also showed how tonic dopamine can appear to affect learning while only directly altering the trade-off. Thus, our models support the hypothesis that changes in tonic dopamine within the striatum can alter the exploration-exploitation trade-off by modulating the output of the basal ganglia. PMID:22347155

  20. The offspring quantity–quality trade-off and human fertility variation

    Science.gov (United States)

    Lawson, David W.; Borgerhoff Mulder, Monique

    2016-01-01

    The idea that trade-offs between offspring quantity and quality shape reproductive behaviour has long been central to economic perspectives on fertility. It also has a parallel and richer theoretical foundation in evolutionary ecology. We review the application of the quantity–quality trade-off concept to human reproduction, emphasizing distinctions between clutch size and lifetime fertility, and the wider set of forces contributing to fertility variation in iteroparous and sexually reproducing species like our own. We then argue that in settings approximating human evolutionary history, several factors limit costly sibling competition. Consequently, while the optimization of quantity–quality trade-offs undoubtedly shaped the evolution of human physiology setting the upper limits of reproduction, we argue it plays a modest role in accounting for socio-ecological and individual variation in fertility. Only upon entering the demographic transition can fertility limitation be clearly interpreted as strategically orientated to advancing offspring quality via increased parental investment per child, with low fertility increasing descendant socio-economic success, although not reproductive success. We conclude that existing economic and evolutionary literature has often overemphasized the centrality of quantity–quality trade-offs to human fertility variation and advocate for the development of more holistic frameworks encompassing alternative life-history trade-offs and the evolved mechanisms guiding their resolution. PMID:27022072

  1. Understanding Space in Proof Complexity: Separations and Trade-offs via Substitutions

    CERN Document Server

    Ben-Sasson, Eli

    2010-01-01

    For current state-of-the-art DPLL SAT-solvers the two main bottlenecks are the amounts of time and memory used. In proof complexity, these resources correspond to the length and space of resolution proofs. There has been a long line of research investigating these proof complexity measures, but while strong results have been established for length, our understanding of space and how it relates to length has remained quite poor. In particular, the question whether resolution proofs can be optimized for length and space simultaneously, or whether there are trade-offs between these two measures, has remained essentially open. In this paper, we remedy this situation by proving a host of length-space trade-off results for resolution. Our collection of trade-offs cover almost the whole range of values for the space complexity of formulas, and most of the trade-offs are superpolynomial or even exponential and essentially tight. Using similar techniques, we show that these trade-offs in fact extend to the exponential...

  2. Ecosystem service trade-offs and synergies misunderstood without landscape history

    Directory of Open Access Journals (Sweden)

    Stephanie A. Tomscha

    2016-03-01

    Full Text Available Dramatic changes in ecosystem services have motivated recent work characterizing their interactions, including identifying trade-offs and synergies. Although time is arguably implicit in these ideas of trade-offs and synergies (e.g., temporal dynamics or changes in ecosystem services, such interactions are routinely inferred based on the spatial relationships among ecosystem services alone (e.g., spatial concordance of ecosystem services indicates synergies, whereas incongruence signifies trade-offs. The limitations of this approach have not been fully explored. We quantified ecosystem service interactions using correlations among contemporary ecosystem services and compared these results to those derived by incorporating change in ecosystem services from an earlier decade. To document change over ~60 years in an urbanizing floodplain, we used aerial photography to map multiple floodplain-associated ecosystem services. Our results demonstrate how incorporating landscape baselines can influence measured synergies and trade-offs. Spatial correlations among contemporary ecosystem services missed several interactions that were detected when using prior baseline ecosystem services. Ignoring the history of ecosystem services and their change over time may result in missed opportunities to foster their synergies and lead to unnecessary trade-offs. Efforts to incorporate ecosystem services into land management should include long-term monitoring and baseline reconstructions of ecosystem services.

  3. The offspring quantity-quality trade-off and human fertility variation.

    Science.gov (United States)

    Lawson, David W; Borgerhoff Mulder, Monique

    2016-04-19

    The idea that trade-offs between offspring quantity and quality shape reproductive behaviour has long been central to economic perspectives on fertility. It also has a parallel and richer theoretical foundation in evolutionary ecology. We review the application of the quantity-quality trade-off concept to human reproduction, emphasizing distinctions between clutch size and lifetime fertility, and the wider set of forces contributing to fertility variation in iteroparous and sexually reproducing species like our own. We then argue that in settings approximating human evolutionary history, several factors limit costly sibling competition. Consequently, while the optimization of quantity-quality trade-offs undoubtedly shaped the evolution of human physiology setting the upper limits of reproduction, we argue it plays a modest role in accounting for socio-ecological and individual variation in fertility. Only upon entering the demographic transition can fertility limitation be clearly interpreted as strategically orientated to advancing offspring quality via increased parental investment per child, with low fertility increasing descendant socio-economic success, although not reproductive success. We conclude that existing economic and evolutionary literature has often overemphasized the centrality of quantity-quality trade-offs to human fertility variation and advocate for the development of more holistic frameworks encompassing alternative life-history trade-offs and the evolved mechanisms guiding their resolution. PMID:27022072

  4. Trade-off study on the power capacity of a prototype SFR in Korea

    Energy Technology Data Exchange (ETDEWEB)

    Baek, M. H.; Kim, S. J.; Yoo, J.; Bae, I. H. [Korea Atomic Energy Research Inst., 1045 Daedeog-daero, Yuseong-gu, 305-353 Daejeon (Korea, Republic of)

    2012-07-01

    The major roles of a prototype SFR are to provide irradiation test capability for the fuel and structure materials, and to obtain operational experiences of systems. Due to a compromise between the irradiation capability and construction costs, the power level should be properly determined. In this paper, a trade-off study on the power level of the prototype SFR was performed from a neutronics viewpoint. To select candidate cores, the parametric study of pin diameters was estimated using 20 wt.% uranium fuel. The candidate cores of different power levels, 125 MWt, 250 MWt, 400 MWt, and 500 MWt, were compared with the 1500 MWt reference core. The resulting core performance and economic efficiency indices became insensitive to the power at about 400-500 MWt and sharply deteriorated at about 125-250 MWt with decreasing core sizes. Fuel management scheme, TRU core performance comparing with uranium core, and sodium void reactivity were also evaluated with increasing power levels. It is found that increasing the number of batches showed higher burnup performance and economic efficiency. However, increasing the cycle length showed the trends in lower economic efficiency. Irradiation performance of TRU and enriched TRU cores was improved about 20 % and 50 %, respectively. The maximum sodium void reactivity of 5.2$ was confirmed less than the design limit of 7.5$. As a result, the power capacity of the prototype SFR should not be less than 250 MWt and would be appropriate at {approx} 500 MWt considering the performance and economic efficiency. (authors)

  5. Centric selection: a way to tune the exploration/exploitation trade-off

    CERN Document Server

    Simoncini, David; Collard, Philippe; Clergue, Manuel; 10.1145/1569901.1570023

    2011-01-01

    In this paper, we study the exploration / exploitation trade-off in cellular genetic algorithms. We define a new selection scheme, the centric selection, which is tunable and allows controlling the selective pressure with a single parameter. The equilibrium model is used to study the influence of the centric selection on the selective pressure and a new model which takes into account problem dependent statistics and selective pressure in order to deal with the exploration / exploitation trade-off is proposed: the punctuated equilibria model. Performances on the quadratic assignment problem and NK-Landscapes put in evidence an optimal exploration / exploitation trade-off on both of the classes of problems. The punctuated equilibria model is used to explain these results.

  6. Ethical Perspective: Five Unacceptable Trade-offs on the Path to Universal Health Coverage

    Directory of Open Access Journals (Sweden)

    Ole Frithjof Norheim

    2015-11-01

    Full Text Available This article discusses what ethicists have called “unacceptable trade-offs” in health policy choices related to universal health coverage (UHC. Since the fiscal space is constrained, trade-offs need to be made. But some trade-offs are unacceptable on the path to universal coverage. Unacceptable choices include, among other examples from low-income countries, to expand coverage for services with lower priority such as coronary bypass surgery before securing universal coverage for high-priority services such as skilled birth attendance and services for easily preventable or treatable fatal childhood diseases. Services of the latter kind include oral rehydration therapy for children with diarrhea and antibiotics for children with pneumonia. The article explains why such trade-offs are unfair and unacceptable even if political considerations may push in the opposite direction.

  7. Is There Evidence for a Mixture of Processes in Speed-Accuracy Trade-Off Behavior?

    Science.gov (United States)

    van Maanen, Leendert

    2016-01-01

    The speed-accuracy trade-off (SAT) effect refers to the behavioral trade-off between fast yet error-prone respones and accurate but slow responses. Multiple theories on the cognitive mechanisms behind SAT exist. One theory assumes that SAT is a consequence of strategically adjusting the amount of evidence required for overt behaviors, such as perceptual choices. Another theory hypothesizes that SAT is the consequence of the mixture of multiple categorically different cognitive processes. In this paper, these theories are disambiguated by assessing whether the fixed-point property of mixture distributions holds, in both simulations and data. I conclude that, at least for perceptual decision making, there is no evidence for a mixture of different cognitive processes to trade off accuracy of responding for speed. PMID:26748686

  8. Dual worth trade-off method and its application for solving multiple criteria decision making problems

    Institute of Scientific and Technical Information of China (English)

    Feng Junwen

    2006-01-01

    To overcome the limitations of the traditional surrogate worth trade-off (SWT) method and solve the multiple criteria decision making problem more efficiently and interactively, a new method labeled dual worth trade-off (DWT) method is proposed. The DWT method dynamically uses the duality theory related to the multiple criteria decision making problem and analytic hierarchy process technique to obtain the decision maker's solution preference information and finally find the satisfactory compromise solution of the decision maker. Through the interactive process between the analyst and the decision maker, trade-off information is solicited and treated properly, the representative subset of efficient solutions and the satisfactory solution to the problem are found. The implementation procedure for the DWT method is presented. The effectiveness and applicability of the DWT method are shown by a practical case study in the field of production scheduling.

  9. Ecosystem service trade-offs, perceived drivers, and sustainability in contrasting agroecosystems in central Mexico

    Directory of Open Access Journals (Sweden)

    2015-03-01

    Full Text Available The ability of agroecosystems to provide food ultimately depends on the regulating and supporting ecosystem services that underpin their functioning, such as the regulation of soil quality, water quality, soil erosion, pests, and pollinators. However, there are trade-offs between provisioning and regulating or supporting services, whose nature at the farm and plot scales is poorly understood. We analyzed data at the farm level for two agroecosystems with contrasting objectives in central Mexico: one aimed at staple crop production for self-subsistence and local markets, the other directed to a cash crop for export markets. Bivariate and multivariate trade-offs were analyzed for different crop management strategies (conventional, organic, traditional, crop rotation and their underpinning socioeconomic drivers. There was a clear trade-off between crop yield and soil quality in self-subsistence systems. However, other expected trade-offs between yields and soil quality did not always occur, likely because of the overall good soils of the region and the low to medium input profile of most farms. Trade-offs were highly dependent on farm-specific agricultural practices; organic, traditional, and rotation management systems generally showed smaller trade-offs between yield and soil quality, pest control, and biodiversity than did conventional management systems. Perceived drivers reported by farmers included increasing prices for cash crops, rising costs of inputs, and extreme climatic events (e.g., drought, hail, frost. Farmers did not identify the regulation of soil quality, water quality, soil erosion, pests, or pollinators as important constraints. Although acceptable yields could be maintained irrespective of key regulating and supporting services according to these perceptions, current levels of soil erosion and nutrient runoff are likely to have important negative effects at the watershed scale. Sustainability in both agroecosystems could be

  10. Non Classical Design in MOSFETs for Improving OTA gain-bandwidth trade off

    OpenAIRE

    Armstrong, Alastair

    2010-01-01

    In this paper, gain-bandwidth (GB) trade-off associated with analog device/circuit design due to conflicting requirements for enhancing gain and cutoff frequency is examined. It is demonstrated that the use of a nonclassical source/drain (S/D) profile (also known as underlap channel) can alleviate the GB trade-off associated with analog design. Operational transconductance amplifier (OTA) with 60 nm underlap S/D MOSFETs achieve 15 dB higher open loop voltage gain along with three times higher...

  11. Selection and constraints on offspring size-number trade-offs in sand lizards (Lacerta agilis).

    Science.gov (United States)

    Ljungström, G; Stjernstedt, M; Wapstra, E; Olsson, M

    2016-05-01

    The trade-off between offspring size and number is a central component of life-history theory, postulating that larger investment into offspring size inevitably decreases offspring number. This trade-off is generally discussed in terms of genetic, physiological or morphological constraints; however, as among-individual differences can mask individual trade-offs, the underlying mechanisms may be difficult to reveal. In this study, we use multivariate analyses to investigate whether there is a trade-off between offspring size and number in a population of sand lizards by separating among- and within-individual patterns using a 15-year data set collected in the wild. We also explore the ecological and evolutionary causes and consequences of this trade-off by investigating how a female's resource (condition)- vs. age-related size (snout-vent length) influences her investment into offspring size vs. number (OSN), whether these traits are heritable and under selection and whether the OSN trade-off has a genetic component. We found a negative correlation between offspring size and number within individual females and physical constraints (size of body cavity) appear to limit the number of eggs that a female can produce. This suggests that the OSN trade-off occurs due to resource constraints as a female continues to grow throughout life and, thus, produces larger clutches. In contrast to the assumptions of classic OSN theory, we did not detect selection on offspring size; however, there was directional selection for larger clutch sizes. The repeatabilities of both offspring size and number were low and we did not detect any additive genetic variance in either trait. This could be due to strong selection (past or current) on these life-history traits, or to insufficient statistical power to detect significant additive genetic effects. Overall, the findings of this study are an important illustration of how analyses of within-individual patterns can reveal trade-offs and

  12. Comparing the Pecking Order Theory and the Trade-off Theory: Some UK Evidence

    OpenAIRE

    Luo,Man

    2011-01-01

    This dissertation compares the pecking order theory and the trade-off theory by utilizing UK 47 companies from the FTSE 100 during the period of 2000 and 2009. Evidences observed show that the trade-off theory has more power of explaining the UK capital structure, and the partial adjustment model confirms that many companies tend to main an optimal target leverage and converge to the target quickly. On the other hand, when using the financial deficit model to investigate the pecking order the...

  13. Trade-off between phase-noise and signal quadrature in unilaterally coupled oscillators

    DEFF Research Database (Denmark)

    Djurhuus, Torsten; Krozer, Viktor; Vidkjær, Jens;

    2005-01-01

    We present a comprehensive nonlinear analysis of coupled oscillators and examine the trade-off between phase-noise of the oscillator and the quadrature precision. We show that asymmetry gives rise to amplitude and phase imbalance which are proportional to the inverse and inverse square, respectiv......We present a comprehensive nonlinear analysis of coupled oscillators and examine the trade-off between phase-noise of the oscillator and the quadrature precision. We show that asymmetry gives rise to amplitude and phase imbalance which are proportional to the inverse and inverse square...

  14. Selection and constraints on offspring size-number trade-offs in sand lizards (Lacerta agilis).

    Science.gov (United States)

    Ljungström, G; Stjernstedt, M; Wapstra, E; Olsson, M

    2016-05-01

    The trade-off between offspring size and number is a central component of life-history theory, postulating that larger investment into offspring size inevitably decreases offspring number. This trade-off is generally discussed in terms of genetic, physiological or morphological constraints; however, as among-individual differences can mask individual trade-offs, the underlying mechanisms may be difficult to reveal. In this study, we use multivariate analyses to investigate whether there is a trade-off between offspring size and number in a population of sand lizards by separating among- and within-individual patterns using a 15-year data set collected in the wild. We also explore the ecological and evolutionary causes and consequences of this trade-off by investigating how a female's resource (condition)- vs. age-related size (snout-vent length) influences her investment into offspring size vs. number (OSN), whether these traits are heritable and under selection and whether the OSN trade-off has a genetic component. We found a negative correlation between offspring size and number within individual females and physical constraints (size of body cavity) appear to limit the number of eggs that a female can produce. This suggests that the OSN trade-off occurs due to resource constraints as a female continues to grow throughout life and, thus, produces larger clutches. In contrast to the assumptions of classic OSN theory, we did not detect selection on offspring size; however, there was directional selection for larger clutch sizes. The repeatabilities of both offspring size and number were low and we did not detect any additive genetic variance in either trait. This could be due to strong selection (past or current) on these life-history traits, or to insufficient statistical power to detect significant additive genetic effects. Overall, the findings of this study are an important illustration of how analyses of within-individual patterns can reveal trade-offs and

  15. Science for Trade-Offs Between Conflicting Interests in Future Forests

    Directory of Open Access Journals (Sweden)

    Sune Linder

    2011-08-01

    Full Text Available Forests deliver multiple ecosystem services to society. Management of forests must be able to deal with trade-offs when the delivery of different ecosystem services comes in conflict with each other. The research program Future Forests (http://www.futureforests.se attempts to form a scientific basis for managing such trade-offs between conflicting interests in northern boreal forests. Some key characteristics of the research program are interdisciplinary and participatory research and a clear communication agenda for stakeholders. This paper gives a brief overview of the underlying ideas behind the program, and an introduction to the papers published in this Special Issue.

  16. Analysis of self-overlap reveals trade-offs in plankton swimming trajectories

    DEFF Research Database (Denmark)

    Mariani, Patrizio; Visser, Andre W.; Mazzocchi, Maria Grazia;

    2014-01-01

    these contrasting processes. This trade-off can be hypothesized as being evident in the behaviour of plankton, which inhabit a dilute three-dimensional environment with few refuges or orienting landmarks. We present an analysis of the swimming path geometries based on a volumetric Monte Carlo sampling approach......, which is particularly adept at revealing such trade-offs by measuring the self-overlap of the trajectories. Application of this method to experimentally measured trajectories reveals that swimming patterns in copepods are shaped to efficiently explore volumes at small scales, while achieving a large...

  17. Having it all: historical energy intakes do not generate the anticipated trade-offs in fecundity

    OpenAIRE

    Johnston, S L; Grune, T; Bell, L M; S. J. Murray; Souter, D.M; Erwin, S.S; Yearsley, J.M; Gordon, I.J; Illius, A. W.; Kyriazakis, I; Speakman, J. R.

    2006-01-01

    An axiom of life-history theory, and fundamental to our understanding of ageing, is that animals must trade-off their allocation of resources since energy and nutrients are limited. Therefore, animals cannot ‘have it all’—combine high rates of fecundity with extended lifespans. The idea of life-history trade-offs was recently challenged by the discovery that ageing may be governed by a small subset of molecular processes independent of fitness. We tested the ‘trade-off’ and ‘having it all’ th...

  18. Experimental manipulation of female reproduction reveals an intraspecific egg size-clutch size trade-off.

    OpenAIRE

    Williams, T. D.

    2001-01-01

    A negative relationship, or trade-off, between egg size and clutch size is a central and long-standing component of life-history theory, yet there is little empirical evidence for such a trade-off, especially at the intraspecific level. Here, I show that female zebra finches (Taeniopygia guttata) treated chronically during egg formation with the anti-oestrogen tamoxifen lay smaller eggs (by 8%) but produce larger clutches (on average two eggs more) than controls. Decreased egg mass in tamoxif...

  19. Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off

    Science.gov (United States)

    Li, Zhiming; Pradeep, Konda Gokuldoss; Deng, Yun; Raabe, Dierk; Tasan, Cemal Cem

    2016-06-01

    Metals have been mankind’s most essential materials for thousands of years; however, their use is affected by ecological and economical concerns. Alloys with higher strength and ductility could alleviate some of these concerns by reducing weight and improving energy efficiency. However, most metallurgical mechanisms for increasing strength lead to ductility loss, an effect referred to as the strength-ductility trade-off. Here we present a metastability-engineering strategy in which we design nanostructured, bulk high-entropy alloys with multiple compositionally equivalent high-entropy phases. High-entropy alloys were originally proposed to benefit from phase stabilization through entropy maximization. Yet here, motivated by recent work that relaxes the strict restrictions on high-entropy alloy compositions by demonstrating the weakness of this connection, the concept is overturned. We decrease phase stability to achieve two key benefits: interface hardening due to a dual-phase microstructure (resulting from reduced thermal stability of the high-temperature phase); and transformation-induced hardening (resulting from the reduced mechanical stability of the room-temperature phase). This combines the best of two worlds: extensive hardening due to the decreased phase stability known from advanced steels and massive solid-solution strengthening of high-entropy alloys. In our transformation-induced plasticity-assisted, dual-phase high-entropy alloy (TRIP-DP-HEA), these two contributions lead respectively to enhanced trans-grain and inter-grain slip resistance, and hence, increased strength. Moreover, the increased strain hardening capacity that is enabled by dislocation hardening of the stable phase and transformation-induced hardening of the metastable phase produces increased ductility. This combined increase in strength and ductility distinguishes the TRIP-DP-HEA alloy from other recently developed structural materials. This metastability-engineering strategy should

  20. Metastable high-entropy dual-phase alloys overcome the strength-ductility trade-off.

    Science.gov (United States)

    Li, Zhiming; Pradeep, Konda Gokuldoss; Deng, Yun; Raabe, Dierk; Tasan, Cemal Cem

    2016-06-01

    Metals have been mankind's most essential materials for thousands of years; however, their use is affected by ecological and economical concerns. Alloys with higher strength and ductility could alleviate some of these concerns by reducing weight and improving energy efficiency. However, most metallurgical mechanisms for increasing strength lead to ductility loss, an effect referred to as the strength-ductility trade-off. Here we present a metastability-engineering strategy in which we design nanostructured, bulk high-entropy alloys with multiple compositionally equivalent high-entropy phases. High-entropy alloys were originally proposed to benefit from phase stabilization through entropy maximization. Yet here, motivated by recent work that relaxes the strict restrictions on high-entropy alloy compositions by demonstrating the weakness of this connection, the concept is overturned. We decrease phase stability to achieve two key benefits: interface hardening due to a dual-phase microstructure (resulting from reduced thermal stability of the high-temperature phase); and transformation-induced hardening (resulting from the reduced mechanical stability of the room-temperature phase). This combines the best of two worlds: extensive hardening due to the decreased phase stability known from advanced steels and massive solid-solution strengthening of high-entropy alloys. In our transformation-induced plasticity-assisted, dual-phase high-entropy alloy (TRIP-DP-HEA), these two contributions lead respectively to enhanced trans-grain and inter-grain slip resistance, and hence, increased strength. Moreover, the increased strain hardening capacity that is enabled by dislocation hardening of the stable phase and transformation-induced hardening of the metastable phase produces increased ductility. This combined increase in strength and ductility distinguishes the TRIP-DP-HEA alloy from other recently developed structural materials. This metastability-engineering strategy should

  1. Mechanistic links between cellular trade-offs, gene expression, and growth.

    Science.gov (United States)

    Weiße, Andrea Y; Oyarzún, Diego A; Danos, Vincent; Swain, Peter S

    2015-03-01

    Intracellular processes rarely work in isolation but continually interact with the rest of the cell. In microbes, for example, we now know that gene expression across the whole genome typically changes with growth rate. The mechanisms driving such global regulation, however, are not well understood. Here we consider three trade-offs that, because of limitations in levels of cellular energy, free ribosomes, and proteins, are faced by all living cells and we construct a mechanistic model that comprises these trade-offs. Our model couples gene expression with growth rate and growth rate with a growing population of cells. We show that the model recovers Monod's law for the growth of microbes and two other empirical relationships connecting growth rate to the mass fraction of ribosomes. Further, we can explain growth-related effects in dosage compensation by paralogs and predict host-circuit interactions in synthetic biology. Simulating competitions between strains, we find that the regulation of metabolic pathways may have evolved not to match expression of enzymes to levels of extracellular substrates in changing environments but rather to balance a trade-off between exploiting one type of nutrient over another. Although coarse-grained, the trade-offs that the model embodies are fundamental, and, as such, our modeling framework has potentially wide application, including in both biotechnology and medicine.

  2. The lack of theoretical support for using person trade-offs in QALY-type models

    DEFF Research Database (Denmark)

    Østerdal, Lars Peter Raahave

    2009-01-01

    -adjusted life years (DALYs). This paper discusses the theoretical support for the use of person trade-offs in QALY-type measurement of (changes in) population health. It argues that measures of this type based on such quality-adjustment factors almost always violate the Pareto principle, and so lack normative...

  3. Trade-offs between different early childhood interventions: evidence from Ecuador.

    NARCIS (Netherlands)

    J.A. Rosero Moncayo; H. Oosterbeek

    2011-01-01

    Using a discontinuity in the funding scheme, we evaluate the impact of home visits and of child care centers on children and their mothers from poor families in Ecuador. The two interventions represent a trade-off between child outcomes and mother’s psychic well-being on the one hand, and labor mark

  4. Educational systems and the trade-off between labor market allocation and equality of educational opportunity

    NARCIS (Netherlands)

    T. Bol; H.G. van de Werfhorst

    2013-01-01

    Educational systems with a high level of tracking and vocational orientation have been shown to improve the allocation of school-leavers in the labor market. However, tracked educational systems are also known to increase inequality of educational opportunity. This presumed trade-off between equalit

  5. Educational Systems and the Trade-Off between Labor Market Allocation and Equality of Educational Opportunity

    Science.gov (United States)

    Bol, Thijs; van de Werfhorst, Herman G.

    2013-01-01

    Educational systems with a high level of tracking and vocational orientation have been shown to improve the allocation of school-leavers in the labor market. However, tracked educational systems are also known to increase inequality of educational opportunity. This presumed trade-off between equality and labor market preparation is clearly rooted…

  6. Trade-off relation between information and disturbance in quantum measurement

    Science.gov (United States)

    Shitara, Tomohiro; Kuramochi, Yui; Ueda, Masahito

    2016-03-01

    We formulate a trade-off relation between information and disturbance in quantum measurement from an estimation-theoretic point of view. The information and disturbance are characterized in terms of the classical Fisher information and the average loss of the quantum Fisher information, respectively. We identify the necessary condition for various divergences between two quantum states to satisfy similar relations.

  7. The developmental roots of the speed-accuracy trade-off

    NARCIS (Netherlands)

    Zaal, FTJM; Thelen, E

    2005-01-01

    The speed of adult reaching movements is lawfully related to the distance of the reach and the size of the target. The authors had 7-, 9-, and 11-month-old infants reach for small and large targets to investigate a possible relation between the emergence of this speed-accuracy trade-off and the impr

  8. Adaptively evolved yeast mutants on galactose show trade-offs in carbon utilization on glucose

    DEFF Research Database (Denmark)

    Hong, Kuk-Ki; Nielsen, Jens

    2013-01-01

    Adaptive evolution offers many opportunities in metabolic engineering; however, several constraints still exist as evolutionary trade-offs may impose collateral cost to obtain new traits. The application of adaptive evolution for strains development could be further improved by elucidating the mo...

  9. Trade-Offs in the Study of Culture and Development: Theories, Methods, and Values.

    Science.gov (United States)

    Rothbaum, Fred; Pott, Martha; Azuma, Hiroshi; Miyake, Kazuo; Weisz, John

    2000-01-01

    Notes that commentators unanimously support Rothbaum et al.'s general orientation to culture and development and their developmental pathways. Views commentators' suggestions as relating to trade-offs: between theories that highlight generalization or exceptions; between methods that rely on one-, two-, or multiculture studies; and between values…

  10. A phase transition model for the speed-accuracy trade-off in response time experiments

    NARCIS (Netherlands)

    G. Dutilh; E.-J. Wagenmakers; I. Visser; H.L.J. van der Maas

    2011-01-01

    Most models of response time (RT) in elementary cognitive tasks implicitly assume that the speed-accuracy trade-off is continuous: When payoffs or instructions gradually increase the level of speed stress, people are assumed to gradually sacrifice response accuracy in exchange for gradual increases

  11. Environmental trade-offs of tunnels vs cut-and-cover subways

    Science.gov (United States)

    Walton, M.

    1978-01-01

    Heavy construction projects in cities entail two kinds of cost - internal cost, which can be defined in terms of payments from one set of parties to another, and external cost, which is the cost borne by the community at large as the result of disutilities entailed in construction and operation. Environmental trade-offs involve external costs, which are commonly difficult to measure. Cut-and-cover subway construction probably entails higher external and internal cost than deep tunnel construction in many urban geological environments, but uncertainty concerning the costs and environmental trade-offs of tunneling leads to limited and timid use of tunneling by American designers. Thus uncertainty becomes a major trade-off which works against tunneling. The reverse is true in Sweden after nearly 30 years of subway construction. Econometric methods for measuring external costs exist in principle, but are limited in application. Economic theory based on market pressure does not address the real problem of urban environmental trade-offs. Nevertheless, the problem of uncertainty can be addressed by comparative studies of estimated and as-built costs of cut-and-cover vs tunnel projects and a review of environmental issues associated with such construction. Such a study would benefit the underground construction industry and the design of transportation systems. It would also help solve an aspect of the urban problem. ?? 1978.

  12. The Problems of Flexibility, Fluency, and Speed-Accuracy Trade-Off in Skilled Behavior.

    Science.gov (United States)

    MacKay, Donald G.

    1982-01-01

    A theory of practice in high-proficiency skills such as speech production is proposed, involving activation of a hierarchy of nodes in serial order within an output system of behavior. Increased flexibility with practice, response mechanism transfer in skills, motor equivalence, automaticity, and speed-accuracy trade-off are discussed. (Author/CM)

  13. Compact and resource efficient cities? Synergies and trade-offs in European cities

    DEFF Research Database (Denmark)

    Fertner, Christian; Große, Juliane

    2016-01-01

    city. Compact cities and compact urban development are thought to decrease energy and resource demand per capita and increase efficiency. At the same time trade-offs and potential rebound effects of increased resource efficiency question certain achievements of a dense urban structure. This paper...

  14. The Child Quantity-Quality Trade-Off During the Industrial Revolution in England

    DEFF Research Database (Denmark)

    Klemp, Marc; Weisdorf, Jacob L.

    We take Gary Becker's child quantity-quality trade-off hypothesis to the historical record, investigating the causal link from family size to the literacy status of offspring using data from Anglican parish registers, c. 1700-1830. Extraordinarily forhistorical data, the parish records enable us...

  15. Energy-bandwidth trade-off in all-optical photonic crystal microcavity switches

    DEFF Research Database (Denmark)

    Heuck, Mikkel; Kristensen, Philip Trøst; Mørk, Jesper

    2011-01-01

    . As a specific example of a switching application, we investigate the demultiplexing of an optical time division multiplexed signal. To quantify the energy-bandwidth trade-off, we introduce a figure of merit for the detection of the demultiplexed signal. In such investigations it is crucial to consider...

  16. Slow Steaming in Maritime Transportation: Fundamentals, Trade-offs, and Decision Models

    DEFF Research Database (Denmark)

    Psaraftis, Harilaos N.; Kontovas, Christos A.

    2015-01-01

    burned. The purpose of this chapter is to examine the practice of slow steaming from various angles. In that context, a taxonomy of models is presented, some fundamentals are outlined, the main trade-offs are analysed, and some decision models are presented. Some examples are finally presented so...

  17. Trade off study on different envelope detectors for B-mode imaging

    DEFF Research Database (Denmark)

    Schlaikjer, Malene; Bagge, J. P.; Jensen, Jørgen Arendt

    2003-01-01

    Generation of B-mode images involves envelope detection of the RF-signals. Various detection algorithms are available. A trade off between performance, price, and complexity determines the choice of algorithm in an ultrasound system. A Hilbert Transform (HT) and a subsequent computation...

  18. Optimal Time-Space Trade-Offs for Non-Comparison-Based Sorting

    DEFF Research Database (Denmark)

    Pagh, Rasmus; Pagter, Jacob Illeborg

    2002-01-01

    We study the problem of sorting n integers of w bits on a unit-cost RAM with word size w, and in particular consider the time-space trade-off (product of time and space in bits) for this problem. For comparison-based algorithms, the time-space complexity is known to be Θ(n2). A result of Beame...

  19. Modelling the Volatility-Return Trade-off when Volatility may be Nonstationary

    DEFF Research Database (Denmark)

    Dahl, Christian Møller; Iglesias, Emma M.

    In this paper a new GARCH-M type model, denoted the GARCH-AR, is proposed. In particular, it is shown that it is possible to generate a volatility-return trade-off in a regression model simply by introducing dynamics in the standardized disturbance process. Importantly, the volatility in the GARCH...

  20. Bandwidth-length trade-off figures of merit for electro-optic traveling wave modulators

    OpenAIRE

    Ibarra Fusté, Jose Antonio; Santos Blanco, M. Concepción

    2013-01-01

    Closed-form expressions explicitly relating modulation bandwidth and active length in electro-optic traveling wave modulators are presented which fully account for skin-effect electrode loss and optical-electrical wave velocities mismatch. Four operative margins have been identified where the bandwidth–length trade-off figure of merit takes simple forms. Peer Reviewed

  1. Valuing trade-offs of river ecosystem services in large hydropower development in Tibet, China

    Science.gov (United States)

    Yu, B.; Xu, L.

    2015-12-01

    Hydropower development can be considered as a kind of trade-offs of ecosystem services generated by human activity for their economic and energy demand, because it can increase some river ecosystem services but decrease others. In this context, an ecosystem service trade-off framework in hydropower development was proposed in this paper. It aims to identify the ecological cost of river ecosystem and serve for the ecological compensation during hydropower development, for the hydropower services cannot completely replace the regulating services of river ecosystem. The valuing trade-offs framework was integrated by the influenced ecosystem services identification and ecosystem services valuation, through ecological monitoring and ecological economic methods, respectively. With a case study of Pondo hydropower project in Tibet, China, the valuing trade-offs of river ecosystem services in large hydropower development was illustrated. The typical ecological factors including water, sediment and soil were analyzed in this study to identify the altered river ecosystem services by Pondo hydropower project. Through the field monitoring and valuation, the results showed that the Lhasa River ecosystem services value could be changed annually by Pondo hydropower project with the increment of 5.7E+8CNY, and decrement of 5.1E+7CNY. The ecological compensation for river ecosystem should be focus on water and soil conservation, reservoir dredging and tributaries habitat protection.

  2. Ethical Implications of Validity-vs.-Reliability Trade-Offs in Educational Research

    Science.gov (United States)

    Fendler, Lynn

    2016-01-01

    In educational research that calls itself empirical, the relationship between validity and reliability is that of trade-off: the stronger the bases for validity, the weaker the bases for reliability (and vice versa). Validity and reliability are widely regarded as basic criteria for evaluating research; however, there are ethical implications of…

  3. Energy-delay trade-off of wireless data collection in the plane

    NARCIS (Netherlands)

    Mitici, Mihaela; Goseling, Jasper; Graaf, de Maurits; Boucherie, Richard J.

    2014-01-01

    We analyze the Pareto front of the delay of collecting data from wireless devices located in the plane according to a Poisson process and the energy needed by the devices to transmit their observations. Fundamental bounds on the energy-delay trade-off over the space of all achievable scheduling stra

  4. Spiders in Motion: Demonstrating Adaptation, Structure-Function Relationships, and Trade-Offs in Invertebrates

    Science.gov (United States)

    Bowlin, Melissa S.; McLeer, Dorothy F.; Danielson-Francois, Anne M.

    2014-01-01

    Evolutionary history and structural considerations constrain all aspects of animal physiology. Constraints on invertebrate locomotion are especially straightforward for students to observe and understand. In this exercise, students use spiders to investigate the concepts of adaptation, structure-function relationships, and trade-offs. Students…

  5. Wideband vs. Multiband Trade-offs for a Scalable Multifunction RF system

    NARCIS (Netherlands)

    Huizing, A.G.

    2005-01-01

    This paper presents a concept for a scalable multifunction RF (SMRF) system that allows the RF functionality (radar, electronic warfare and communications) to be easily extended and the RF performance to be scaled to the requirements of different missions and platforms. A trade-off analysis is perfo

  6. Diversity-Multiplexing Trade-off for Coordinated Direct and Relay Schemes

    DEFF Research Database (Denmark)

    Thai, Chan; Popovski, Petar; De Carvalho, Elisabeth;

    2013-01-01

    Direct/Relay (CDR) schemes, which involve two flows, of a direct and a relayed user. In this paper we characterize a CDR scheme by deriving/bounding the Diversity-Multiplexing Trade-off (DMT) function. Two cases are considered. In the first case a transmitter knows the Channel State Information (CSI...

  7. The rate-size trade-off structures intraspecific variation in Daphnia ambigua life history parameters.

    Directory of Open Access Journals (Sweden)

    John P DeLong

    Full Text Available The identification of trade-offs is necessary for understanding the evolution and maintenance of diversity. Here we employ the supply-demand (SD body size optimization model to predict a trade-off between asymptotic body size and growth rate. We use the SD model to quantitatively predict the slope of the relationship between asymptotic body size and growth rate under high and low food regimes and then test the predictions against observations for Daphnia ambigua. Close quantitative agreement between observed and predicted slopes at both food levels lends support to the model and confirms that a 'rate-size' trade-off structures life history variation in this population. In contrast to classic life history expectations, growth and reproduction were positively correlated after controlling for the rate-size trade-off. We included 12 Daphnia clones in our study, but clone identity explained only some of the variation in life history traits. We also tested the hypothesis that growth rate would be positively related to intergenic spacer length (i.e. the growth rate hypothesis across clones, but we found that clones with intermediate intergenic spacer lengths had larger asymptotic sizes and slower growth rates. Our results strongly support a resource-based optimization of body size following the SD model. Furthermore, because some resource allocation decisions necessarily precede others, understanding interdependent life history traits may require a more nested approach.

  8. Sex allocation in California oaks: trade-offs or resource tracking?

    Directory of Open Access Journals (Sweden)

    Johannes M H Knops

    Full Text Available Trade-offs in sex resource allocation are commonly inferred from a negative correlation between male and female reproduction. We found that for three California oak species, aboveground annual net productivity (ANP differences among individuals were primarily correlated with water availability and soil fertility. Reproductive biomass increased with ANP, but the relative allocation to reproduction was constant, indicating that reproduction tracked productivity, which in turn tracked site quality. Although there was a negative correlation between male and female reproduction, this was not the result of a resource investment trade-off, but rather a byproduct of the positive correlation between female reproductive biomass and ANP combined with the greater overall resource allocation to female, compared to male, function. Thus, we reject the hypothesis of a trade-off between these key life-history components within individuals of these species. For long-lived individuals, a plastic resource tracking response to environmental fluctuations may be more adaptive than directly linking life-history traits through trade-offs.

  9. Energy Efficiency - Spectral Efficiency Trade-off: A Multiobjective Optimization Approach

    KAUST Repository

    Amin, Osama

    2015-04-23

    In this paper, we consider the resource allocation problem for energy efficiency (EE) - spectral efficiency (SE) trade-off. Unlike traditional research that uses the EE as an objective function and imposes constraints either on the SE or achievable rate, we propound a multiobjective optimization approach that can flexibly switch between the EE and SE functions or change the priority level of each function using a trade-off parameter. Our dynamic approach is more tractable than the conventional approaches and more convenient to realistic communication applications and scenarios. We prove that the multiobjective optimization of the EE and SE is equivalent to a simple problem that maximizes the achievable rate/SE and minimizes the total power consumption. Then we apply the generalized framework of the resource allocation for the EE-SE trade-off to optimally allocate the subcarriers’ power for orthogonal frequency division multiplexing (OFDM) with imperfect channel estimation. Finally, we use numerical results to discuss the choice of the trade-off parameter and study the effect of the estimation error, transmission power budget and channel-to-noise ratio on the multiobjective optimization.

  10. Publish or patent: bibliometric evidence for empirical trade-offs in national funding strategies

    NARCIS (Netherlands)

    R.D. Shelton; L. Leydesdorff

    2012-01-01

    Multivariate linear regression models suggest a trade-off in allocations of national research and development (R&D). Government funding and spending in the higher education sector encourage publications as a long-term research benefit. Conversely, other components such as industrial funding and spen

  11. Introducing the composite time trade-off: a test of feasibility and face validity

    NARCIS (Netherlands)

    M.F. Janssen (Bas); M. Oppe (Mark); M.M. Versteegh (Matthijs); E.A. Stolk (Elly)

    2013-01-01

    markdownabstract__Abstract__ __Introduction__ This study was designed to test the feasibility and face validity of the composite time trade-off (composite TTO), a new approach to TTO allowing for a more consistent elicitation of negative health state values. __Methods__ The new instrument combin

  12. Trade-offs in ecosystem services and varying stakeholder preferences: evaluating conflicts, obstacles, and opportunities

    Directory of Open Access Journals (Sweden)

    Elizabeth King

    2015-09-01

    Full Text Available In efforts to increase human well-being while maintaining the natural systems and processes upon which we depend, navigating the trade-offs that can arise between different ecosystem services is a profound challenge. We evaluated a recently developed simple analytic framework for assessing ecosystem service trade-offs, which characterizes such trade-offs in terms of their underlying biophysical constraints as well as divergences in stakeholders' values for the services in question. Through a workshop and subsequent discussions, we identified four different types of challenging situations under which the framework allows important insights to clarify the nature of stakeholder conflicts, obstacles to promoting more sustainable outcomes, and potential enabling factors to promote efficiency and sustainability of ecosystem service yields. We illustrated the framework's analytical steps by applying them to case studies representing three of the challenging situations. We explored the fourth challenging situation conceptually, using published literature for examples. We examined the potential utility and feasibility of using the framework as a participatory tool in resource management and conflict resolution. We concluded that the framework can be instrumental for promoting pluralism and insightful analysis of trade-offs. The insights offered here may be viewed as hypotheses to be tested and refined as additional unforeseen challenges and benefits are revealed as the framework is put into practice.

  13. Laser space rendezvous and docking system trade-off study

    Science.gov (United States)

    Adelman, S.; Levinson, S.

    1975-01-01

    The use, design, and fabrication feasibility of scanning the laser beam by swiveling the outside mirror with a ball joint swivel system is examined along with the applicability of graphite reinforced epoxy material for the construction of reflective optics. It is indicated that (1) the cost of graphite-epoxy will be more than that of many other materials due to the amount of special tooling required; (2) the weight advantage of graphite-epoxy over beryllium is minimal; the ball joint swivel system is accurate enough to perform the scanning function; and that the ball joint will result in a simpler and more cost effective scanning mechanism.

  14. Evidence of the trade-off between starvation and predation risks in ducks.

    Directory of Open Access Journals (Sweden)

    Cédric Zimmer

    Full Text Available The theory of trade-off between starvation and predation risks predicts a decrease in body mass in order to improve flight performance when facing high predation risk. To date, this trade-off has mainly been validated in passerines, birds that store limited body reserves for short-term use. In the largest avian species in which the trade-off has been investigated (the mallard, Anas platyrhynchos, the slope of the relationship between mass and flight performance was steeper in proportion to lean body mass than in passerines. In order to verify whether the same case can be applied to other birds with large body reserves, we analyzed the response to this trade-off in two other duck species, the common teal (Anas crecca and the tufted duck (Aythya fuligula. Predation risk was simulated by disturbing birds. Ducks within disturbed groups were compared to non-disturbed control birds. In disturbed groups, both species showed a much greater decrease in food intake and body mass during the period of simulated high risk than those observed in the control group. This loss of body mass allows reaching a more favourable wing loading and increases power for flight, hence enhancing flight performances and reducing predation risk. Moreover, body mass loss and power margin gain in both species were higher than in passerines, as observed in mallards. Our results suggest that the starvation-predation risk trade-off is one of the major life history traits underlying body mass adjustments, and these findings can be generalized to all birds facing predation. Additionally, the response magnitude seems to be influenced by the strategy of body reserve management.

  15. Maize crop residue uses and trade-offs on smallholder crop-livestock farms in Zimbabwe: Economic implications of intensification

    NARCIS (Netherlands)

    Rusinamhodzi, L.; Wijk, van M.T.; Corbeels, M.; Rufino, M.C.; Giller, K.E.

    2015-01-01

    Decisions to use crop residues as soil cover for conservation agriculture create trade-offs for farmers who own cattle in crop-livestock systems. Trade-offs among soil C, crop and animal and crop productivity were analysed using the NUANCES-FARMSIM (FArm-scale Resource Management SIMulator) dynamic

  16. Construct validity of the interview Time Trade-Off and computer Time Trade-Off in patients with rheumatoid arthritis: A cross-sectional observational pilot study

    OpenAIRE

    Buitinga Laurien; Braakman-Jansen Louise MA; Taal Erik; Van de Laar Mart AFJ

    2012-01-01

    Abstract Background The Time Trade-Off (TTO) is a widely used instrument for valuing preference-based health-related quality of life (HRQoL). The TTO reveals preferences for own current health (‘utilities’) on a scale anchored between death (0) and perfect health (1). Limited information on the external validity of the TTO is available. Aim of this pilot study was to examine the construct validity of both an interview TTO and a computer-based TTO in patients with rheumatoid arthritis (RA). Me...

  17. Growth versus the environment - Is there a trade-off?

    Energy Technology Data Exchange (ETDEWEB)

    Kaageson, P.

    1997-04-01

    The intensity of energy and materials use in OECD countries is diminishing over time despite falling metal and energy prices. Material demand is sometimes falling in absolute terms, but there are also a few examples of rapid growth. The supply of fossil fuels and minerals is being exhausted, in some cases at a rapid speed, but the question addressed here is whether the rate of depletion is so fast that there will be no time for technical progress to create adequate substitutes. Overall, this appears not to be the case. The two main industrial metals are very abundant, and most minor metals already have substitutes for many of their applications. A few metals can be expected to become very scarce, but much of the large quantities in use could be recycled. Developments in OECD Europe over the last 25 years have resulted in relative or absolute delinking between economic growth and environmental damage. On the other hand, it is uncertain whether continuing economic development along these lines will in all cases lead to the achievement of sustainable development, even over 25-30 years. Indeed, this study identifies some examples where slower GDP growth would have resulted in less damage (e.g. household waste and emissions of CO{sub 2} and NO{sub x}, and possibly the depletion of fish stocks and the negative impact of forestry and agriculture on biodiversity.) 500 refs

  18. Evaluating the trade-off between mechanical and electrochemical performance of separators for lithium-ion batteries: Methodology and application

    Science.gov (United States)

    Plaimer, Martin; Breitfuß, Christoph; Sinz, Wolfgang; Heindl, Simon F.; Ellersdorfer, Christian; Steffan, Hermann; Wilkening, Martin; Hennige, Volker; Tatschl, Reinhard; Geier, Alexander; Schramm, Christian; Freunberger, Stefan A.

    2016-02-01

    Lithium-ion batteries are in widespread use in electric vehicles and hybrid vehicles. Besides features like energy density, cost, lifetime, and recyclability the safety of a battery system is of prime importance. The separator material impacts all these properties and requires therefore an informed selection. The interplay between the mechanical and electrochemical properties as key selection criteria is investigated. Mechanical properties were investigated using tensile and puncture penetration tests at abuse relevant conditions. To investigate the electrochemical performance in terms of effective conductivity a method based on impedance spectroscopy was introduced. This methodology is applied to evaluate ten commercial separators which allows for a trade-off analysis of mechanical versus electrochemical performance. Based on the results, and in combination with other factors, this offers an effective approach to select suitable separators for automotive applications.

  19. Economic Growth and Income Distribution in Chile: Macroeconomic Trade-Offs Revisited Economic Growth and Income Distribution in Chile: Macroeconomic Trade-Offs Revisited

    Directory of Open Access Journals (Sweden)

    Andrés Solimano

    1992-03-01

    Full Text Available Economic Growth and Income Distribution in Chile: Macroeconomic Trade-Offs Revisited Long run sustainable development requires both sustained growth and an equitable distribution of the fruits of growth and modernization. This paper analyzes the issue of maintaining the dynamic growth momentum of the Chilean economy while at the same time reducing poverty and improving income distribution patterns. The paper identifies the major constraints on growth for the chilean economy and develops a macro model to explore and quantify potential trade offs between growth, poverty reduction and distribution.The model is calibrated with parameters for the Chilean economy and used to examine the effects of various macro policies with distributive content. For example the model shows that an unbalanced increase in government spending (in social rectors of 3 percent of potential GDP, will slow down the rate of growth of GDP by 1 percent, the real exchange rate appreciates (5,4 percent and real wages rise (4.4 percent in a capacity constrained growth regime. The cut in government savings is the driving force behind the deceleration in growth, given a certain current account deficit. The adverse side effect on growth of the social program can be avoided with an increase in taxation or a reduction in other public spending items in order to prevent a decline in public savings.

  20. Linkages between Value based Performance Measurements and risk return trade off: theory and evidence

    Directory of Open Access Journals (Sweden)

    Saban Celik

    2011-12-01

    Full Text Available In this study we attempt to investigate the linkages between value-based performance measurements and risk-return trade off in a way to explain cross sectional asset returns. On the side of value based performance measurements, three groups of variables are used as a sorting factor: traditional measures which consist of accounting based and market based; recently popularized measures such as Economic Value Added and Market Value Added and theoretically sound measures such as foreign investor allocation and firm systematic risk indicators. The goals of the study are (i to show how value based measurements techniques relate to risk return trade off and (ii how these measures affect the cross sectional asset returns in manufacturing industry. Empirical results indicate that foreign investor allocation as a sorting factor produces much more meaningful risk return positive linear relation for cross sectional asset returns than traditional and recently popularized measures.

  1. Delay-area trade-off for MPRM circuits based on hybrid discrete particle swarm optimization

    Institute of Scientific and Technical Information of China (English)

    Jiang Zhidi; Wang Zhenhai; Wang Pengjun

    2013-01-01

    Polarity optimization for mixed polarity Reed-Muller (MPRM) circuits is a combinatorial issue.Based on the study on discrete particle swarm optimization (DPSO) and mixed polarity,the corresponding relation between particle and mixed polarity is established,and the delay-area trade-off of large-scale MPRM circuits is proposed.Firstly,mutation operation and elitist strategy in genetic algorithm are incorporated into DPSO to further develop a hybrid DPSO (HDPSO).Then the best polarity for delay and area trade-off is searched for large-scale MPRM circuits by combining the HDPSO and a delay estimation model.Finally,the proposed algorithm is testified by MCNC Benchmarks.Experimental results show that HDPSO achieves a better convergence than DPSO in terms of search capability for large-scale MPRM circuits.

  2. Research on the fully fuzzy time-cost trade-off based on genetic algorithms

    Institute of Scientific and Technical Information of China (English)

    2005-01-01

    It is very difficult to estimate exact values of time and cost of an activity in project scheduling process because many uncertain factors, such as weather, productivity level, human factors etc. , dynamically affect them during project implementation process. A GAs-based fully fuzzy optimal time-cost trade-off model is presented based on fuzzy sets and genetic algorithms (GAs). In tihs model all parameters and variables are characteristics by fuzzy numbers. And then GAs is adopted to search for the optimal solution to this model. The method solves the time-cost trade-off problems under an uncertain environment and is proved practicable through a giving example in ship building scheduling.

  3. Trade-Off and Synergy among Ecosystem Services in the Guanzhong-Tianshui Economic Region of China.

    Science.gov (United States)

    Qin, Keyu; Li, Jing; Yang, Xiaonan

    2015-11-03

    Natural ecosystems provide society with important goods and services. With rapidly increasing populations and excessive utilization of natural resources, humans have been enhancing the production of some services at the expense of others. Although the need for certain trade-offs between conservation and development is urgent, having only a small number of efficient methods to assess such trade-offs has impeded progress. This study focuses on the evaluation of ecosystem services under different land use schemes. It reveals the spatial and temporal distributions of and changes in ecosystem services. Based on a correlation rate model and distribution mapping, the trade-offs and synergies of these ecosystem services can be found. Here, we also describe a new simple approach to quantify the relationships of every trade-off and synergy. The results show that all ecosystem services possess trade-offs and synergies in the study area. The trend of improving carbon sequestration and water interception indicate that these key ecosystem services have the strongest synergy. And the decrease in regional agricultural production and other services, except water yield, may be considered as trade-offs. The synergy between water yield and agricultural production was the most significant, while the trade-off between water interception and carbon sequestration was the most apparent, according to our interaction quantification model. The results of this study have implications for planning and monitoring the future management of natural capital and ecosystem services, and can be integrated into land use decision-making.

  4. Trade-Off and Synergy among Ecosystem Services in the Guanzhong-Tianshui Economic Region of China

    Directory of Open Access Journals (Sweden)

    Keyu Qin

    2015-11-01

    Full Text Available Natural ecosystems provide society with important goods and services. With rapidly increasing populations and excessive utilization of natural resources, humans have been enhancing the production of some services at the expense of others. Although the need for certain trade-offs between conservation and development is urgent, having only a small number of efficient methods to assess such trade-offs has impeded progress. This study focuses on the evaluation of ecosystem services under different land use schemes. It reveals the spatial and temporal distributions of and changes in ecosystem services. Based on a correlation rate model and distribution mapping, the trade-offs and synergies of these ecosystem services can be found. Here, we also describe a new simple approach to quantify the relationships of every trade-off and synergy. The results show that all ecosystem services possess trade-offs and synergies in the study area. The trend of improving carbon sequestration and water interception indicate that these key ecosystem services have the strongest synergy. And the decrease in regional agricultural production and other services, except water yield, may be considered as trade-offs. The synergy between water yield and agricultural production was the most significant, while the trade-off between water interception and carbon sequestration was the most apparent, according to our interaction quantification model. The results of this study have implications for planning and monitoring the future management of natural capital and ecosystem services, and can be integrated into land use decision-making.

  5. Trade-offs between sexual advertisement and immune function in the pied flycatcher (Ficedula hypoleuca).

    OpenAIRE

    Kilpimaa, Janne; Alatalo, Rauno V.; Siitari, Heli

    2004-01-01

    Good genes models of sexual selection assume that sexual advertisement is costly and thus the level of advertisement honestly reveals heritable viability. Recently it has been suggested that an important cost of sexual advertisement might be impairment of the functioning of the immune system. In this field experiment we investigated the possible trade-offs between immune function and sexual advertisement by manipulating both mating effort and activity of immune defence in male pied flycatcher...

  6. Drought tolerance of tropical tree species : functional traits, trade-offs and species distribution

    OpenAIRE

    Markesteijn, L.

    2010-01-01

    KEY-WORDS: Bolivia, drought tolerance, shade tolerance, functional traits, trade-offs, ecophysiology, species distribution Tropical forests occur under rainfall regimes that vary greatly in the rainfall pattern and frequency and intensity of drought. Consequently water availability is one of the most important environmental factors influencing community structure, species composition, and plant functioning across large-scale rainfall gradients and small-scale topographic gradients within fore...

  7. Trade-off between multiple-copy transformation and entanglement catalysis

    International Nuclear Information System (INIS)

    We demonstrate that multiple copies of a bipartite entangled pure state may serve as a catalyst for certain entanglement transformations while a single copy cannot. Such a state is termed a 'multiple-copy catalyst' for the transformations. A trade-off between the number of copies of source state and that of the catalyst is also observed. These results can be generalized to probabilistic entanglement transformations directly

  8. A sustainability framework for assessing trade-offs in ecosystem services

    OpenAIRE

    Jeannine Cavender-Bares; Stephen Polasky; Elizabeth King; Patricia Balvanera

    2015-01-01

    Achieving sustainability, i.e., meeting the needs of current populations without compromising the needs of future generations, is the major challenge facing global society in the 21st century. Navigating the inherent trade-offs between provisioning, regulating, cultural, and supporting ecosystem services, and doing so in a way that does not compromise natural capital needed to provide services in the future, is critical for sustainable resource management. Here we build upon existing litera...

  9. A trade-off between reproduction and feather growth in the barn swallow (Hirundo rustica.

    Directory of Open Access Journals (Sweden)

    Nicola Saino

    Full Text Available Physiological trade-offs mediated by limiting energy, resources or time constrain the simultaneous expression of major functions and can lead to the evolution of temporal separation between demanding activities. In birds, plumage renewal is a demanding activity, which accomplishes fundamental functions, such as allowing thermal insulation, aerodynamics and socio-sexual signaling. Feather renewal is a very expensive and disabling process, and molt is often partitioned from breeding and migration. However, trade-offs between feather renewal and breeding have been only sparsely studied. In barn swallows (Hirundo rustica breeding in Italy and undergoing molt during wintering in sub-Saharan Africa, we studied this trade-off by removing a tail feather from a large sample of individuals and analyzing growth bar width, reflecting feather growth rate, and length of the growing replacement feather in relation to the stage in the breeding cycle at removal and clutch size. Growth bar width of females and length of the growing replacement feather of both sexes were smaller when the original feather had been removed after clutch initiation. Importantly, in females both growth bar width and replacement feather length were negatively predicted by clutch size, and more strongly so for large clutches and when feather removal occurred immediately after clutch completion. Hence, we found strong, coherent evidence for a trade-off between reproduction, and laying effort in particular, and the ability to generate new feathers. These results support the hypothesis that the derived condition of molting during wintering in long-distance migrants is maintained by the costs of overlapping breeding and molt.

  10. Trade-off bounds for the Pareto surface approximation in multi-criteria IMRT planning.

    Science.gov (United States)

    Serna, J I; Monz, M; Küfer, K H; Thieke, C

    2009-10-21

    One approach to multi-criteria IMRT planning is to automatically calculate a data set of Pareto-optimal plans for a given planning problem in a first phase, and then interactively explore the solution space and decide on the clinically best treatment plan in a second phase. The challenge of computing the plan data set is to ensure that all clinically meaningful plans are covered and that as many clinically irrelevant plans as possible are excluded to keep computation times within reasonable limits. In this work, we focus on the approximation of the clinically relevant part of the Pareto surface, the process that constitutes the first phase. It is possible that two plans on the Pareto surface have a small, clinically insignificant difference in one criterion and a significant difference in another criterion. For such cases, only the plan that is clinically clearly superior should be included into the data set. To achieve this during the Pareto surface approximation, we propose to introduce bounds that restrict the relative quality between plans, the so-called trade-off bounds. We show how to integrate these trade-off bounds into the approximation scheme and study their effects. The proposed scheme is applied to two artificial cases and one clinical case of a paraspinal tumor. For all cases, the quality of the Pareto surface approximation is measured with respect to the number of computed plans, and the range of values occurring in the approximation for different criteria is compared. Through enforcing trade-off bounds, the scheme disregards clinically irrelevant plans during the approximation. Thereby, the number of plans necessary to achieve a good approximation quality can be significantly reduced. Thus, trade-off bounds are an effective tool to focus the planning and to reduce computation time.

  11. Centric selection: a way to tune the exploration/exploitation trade-off

    OpenAIRE

    Simoncini, David; Verel, Sébastien; Collard, Philippe; Clergue, Manuel

    2011-01-01

    In this paper, we study the exploration / exploitation trade-off in cellular genetic algorithms. We define a new selection scheme, the centric selection, which is tunable and allows controlling the selective pressure with a single parameter. The equilibrium model is used to study the influence of the centric selection on the selective pressure and a new model which takes into account problem dependent statistics and selective pressure in order to deal with the exploration / exploitation trade...

  12. Introducing the composite time trade-off: a test of feasibility and face validity

    OpenAIRE

    Janssen, Bas; Oppe, Mark; Versteegh, Matthijs M.; Stolk, Elly

    2013-01-01

    markdownabstract__Abstract__ __Introduction__ This study was designed to test the feasibility and face validity of the composite time trade-off (composite TTO), a new approach to TTO allowing for a more consistent elicitation of negative health state values. __Methods__ The new instrument combines a conventional TTO to elicit values for states regarded better than dead and a lead-time TTO for states worse than dead. __Results__ A total of 121 participants completed the composite TTO for ten E...

  13. Trade-Off Versus Pecking Order Theory in Listed Companies Around The World

    OpenAIRE

    SORANA VĂTAVU

    2012-01-01

    This paper provides an insight into the literature on capital structure and its determinants. The capital structure refers to the specific combination of debt and equity and their use in financing the corporate operations. Considering there are various determinants of corporate financing patters, many theories have been developed over time. From Modigliani and Miller theory, which was the first to examine the impact of capital structure on firm value, the trade-off theory and the pecking orde...

  14. Time-Space Trade-Offs for the Longest Common Substring Problem

    DEFF Research Database (Denmark)

    Starikovskaya, Tatiana; Vildhøj, Hjalte Wedel

    2013-01-01

    The Longest Common Substring problem is to compute the longest substring which occurs in at least d ≥ 2 of m strings of total length n. In this paper we ask the question whether this problem allows a deterministic time-space trade-off using O(n1+ε) time and O(n1-ε) space for 0 ≤ ε ≤ 1. We give...

  15. Labour Market Programmes and the Equity-Efficiency Trade-off

    DEFF Research Database (Denmark)

    Kennes, John; Larsen, Birthe; Tranæs, Torben;

    2005-01-01

    This paper studies labour market policy in a society where differently gifted individuals can invest in training to further increase their labour market productivity and where the government seeks both effiency and equity. Frictions in the matching process create unemployment and differently skil...... being unemployed (for a while) - the typical Active Labour Market Programme - implies a favorable trade-off between equity and efficiency which encourages high spending on training....

  16. Trade-offs among forest value components in community forests of southwestern Amazonia

    Directory of Open Access Journals (Sweden)

    Christopher Baraloto

    2014-12-01

    Full Text Available Contemporary conservation interventions must balance potential trade-offs between multiple ecosystem services. In tropical forests, much attention has focused on the extent to which carbon-based conservation provided by REDD+ policies can also mitigate biodiversity conservation. In the nearly one-third of tropical forests that are community owned or managed, conservation strategies must also balance the multiple uses of forest products that support local livelihoods. Although much discussion has focused on policy options, little empirical evidence exists to evaluate the potential for trade-offs among different tropical forest value components. We assessed multiple components of forest value, including tree diversity, carbon stocks, and both timber and nontimber forest product resources, in forest communities across the trinational frontier of Brazil, Peru, and Bolivia. We installed 69 0.5-ha vegetation plots in local communities, and we characterized 15 components of forest value for each plot. Principal components analyses revealed two major axes of forest value, the first of which defined a trade-off between diversity of woody plant communities (taxonomic and functional versus aboveground biomass and standing timber volume. The second axis described abundance of commercial species, with strong positive loadings for density of timber and nontimber forest products, including Brazil nut (Bertholletia excelsa and copaiba oil (Copaifera spp.. The observed trade-off between different components of forest value suggests a potential for management conflicts prioritizing biodiversity conservation versus carbon stocks in the region. We discuss the potential for integrative indices of forest value for tropical forest conservation.

  17. Staged Combustion Cycle Rocket Engine Design Trade-Offs for Future Advanced Passenger Transport

    OpenAIRE

    Sippel, Martin; Yamashiro, Ryoma

    2012-01-01

    Staged combustion cycle rocket engines with a moderate nominal 16 MPa chamber pressure have been selected as the baseline propulsion system for the visionary intercontinental passenger transport SpaceLiner. Several technical engine design trade-offs are run by numerical simulations and results are pre-sented including: • Fuel rich vs. Full-flow cycle • Useful operational domain in MR • Regenerative cooling options of thrust chamber The engine operational domain is evaluated on ...

  18. 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....

  19. Automobiles on Steroids: Product Attribute Trade-Offs and Technological Progress in the Automobile Sector

    OpenAIRE

    Christopher R. Knittel

    2009-01-01

    New car fleet fuel economy, weight and engine power have changed drastically since 1980. These changes represent both movements along and shifts in the "fuel economy/weight/engine power production possibilities frontier". This paper estimates the technological progress that has occurred since 1980 and the trade-offs that manufacturers and consumers face when choosing between fuel economy, weight and engine power characteristics. The results suggest that if weight, horsepower and torque were h...

  20. Trade-off between mating opportunities and parental care: brood desertion by female Kentish plovers.

    OpenAIRE

    Székely, T; Cuthill, I. C.

    2000-01-01

    Why do some parents care for their young whereas others divorce from their mate and abandon their offspring? This decision is governed by the trade-off between the value of the current breeding event and future breeding prospects. In the precocial Kentish plover Charadrius alexandrinus females frequently, but not always, abandon their broods to be cared for by their mate, and seek new breeding partners within the same season. We have shown previously that females' remating opportunities decli...

  1. Trade-off between travel distance and prioritization of high-reward sites in traplining bumblebees

    OpenAIRE

    Lihoreau, Mathieu; Chittka, Lars; Raine, Nigel

    2011-01-01

    1. Animals exploiting renewable resource patches are faced with complex multi-location routing problems. In many species, individuals visit foraging patches in predictable sequences called traplines. However, whether and how they optimize their routes remains poorly understood. 2. In this study, we demonstrate that traplining bumblebees (Bombus terrestris) make a trade-off between minimizing travel distance and prioritizing the most rewarding feeding locations. 3. Individual bees trained to...

  2. Bet-hedging as an evolutionary game: the trade-off between egg size and number

    OpenAIRE

    Olofsson, Helen; Ripa, Jörgen; Jonzén, Niclas

    2009-01-01

    Bet-hedging theory addresses how individuals should optimize fitness in varying and unpredictable environments by sacrificing mean fitness to decrease variation in fitness. So far, three main bet-hedging strategies have been described: conservative bet-hedging (play it safe), diversified bet-hedging (don’t put all eggs in one basket) and adaptive coin flipping (choose a strategy at random from a fixed distribution). Within this context, we analyse the trade-off between many small eggs (or see...

  3. Sex Allocation in California Oaks: Trade-Offs or Resource Tracking?

    OpenAIRE

    Johannes M H Knops; Koenig, Walter D.

    2012-01-01

    Trade-offs in sex resource allocation are commonly inferred from a negative correlation between male and female reproduction. We found that for three California oak species, aboveground annual net productivity (ANP) differences among individuals were primarily correlated with water availability and soil fertility. Reproductive biomass increased with ANP, but the relative allocation to reproduction was constant, indicating that reproduction tracked productivity, which in turn tracked site qual...

  4. Universal trade-off relation between power and efficiency for heat engines

    OpenAIRE

    Shiraishi, Naoto; Saito, Keiji; Tasaki, Hal

    2016-01-01

    For a general thermodynamic system described as a Markov process, we prove an inequality which shows that nonvanishing heat current inevitably induces dissipation. This leads to a trade-off relation between efficiency and power, with which we establish that a heat engine with nonvanishing power never attains the Carnot efficiency. Our theory applies to systems arbitrarily far from equilibrium, and does not assume any specific symmetry of the model.

  5. Allocation trade-off under climate warming in experimental amphibian populations

    OpenAIRE

    Gao, Xu; Jin, Changnan; Camargo, Arley; Li, Yiming

    2015-01-01

    Climate change could either directly or indirectly cause population declines via altered temperature, rainfall regimes, food availability or phenological responses. However few studies have focused on allocation trade-offs between growth and reproduction under marginal resources, such as food scarce that may be caused by climate warming. Such critical changes may have an unpredicted impact on amphibian life-history parameters and even population dynamics. Here, we report an allocation strateg...

  6. TRADE-OFF ANALYSIS OF HERBICIDE WITHDRAWALS ON AGRICULTURAL PRODUCTION AND GROUNDWATER QUALITY

    OpenAIRE

    Liu, Shiping; Carlson, Gerald A.; Hoag, Dana L.

    1995-01-01

    This study examines the trade-off between agricultural production and groundwater contamination potential for ten potential herbicide cancellations. Theoretical and empirical models are developed for estimating losses in consumer and producer benefits in the agricultural commodity market and changes in groundwater quality. Using corn and soybean production in the southeastern Coastal Plain as a study area, the analysis concludes that (1) effects of herbicide cancellations on groundwater quali...

  7. A sustainability framework for assessing trade-offs in ecosystem services

    Directory of Open Access Journals (Sweden)

    Jeannine Cavender-Bares

    2015-03-01

    Full Text Available Achieving sustainability, i.e., meeting the needs of current populations without compromising the needs of future generations, is the major challenge facing global society in the 21st century. Navigating the inherent trade-offs between provisioning, regulating, cultural, and supporting ecosystem services, and doing so in a way that does not compromise natural capital needed to provide services in the future, is critical for sustainable resource management. Here we build upon existing literature, primarily from economics and ecology, to present an analytical framework that integrates (1 the ecological mechanisms that underpin ecosystem services, (2 biophysical trade-offs and inherent limits that constrain management options, (3 preferences and values of stakeholders, and (4 explicit analysis of how systems evolve through time to ensure the goal of meeting the needs of future generations. Well-known ecological models define the relationships and trade-offs among services that represents an "efficiency frontier." Well-known methods in economics that combine preferences that define the willingness of stakeholders to trade off ecosystem services on the efficiency frontiers illuminate desirable outcomes that meet human needs. System dynamics show how the system will evolve with consequent impacts on ecosystem services and human well-being and the effects this has on achieving sustainability. Heterogeneity in biophysical constraints, uncertainty, technological advances, and obstacles imposed by societal factors and governance regimes influence potential and realized ecosystem services. Using a set of contrasting scenarios, we illustrate how progress can be made toward sustainability and the important obstacles that must be addressed in doing so. Our framework for analyzing sustainability drawn from economics and ecology is intended to make an integration of concepts from both disciplines accessible to a wider audience.

  8. Speed–accuracy trade-offs during foraging decisions in the acellular slime mould Physarum polycephalum

    OpenAIRE

    Latty, Tanya; Beekman, Madeleine

    2010-01-01

    Speed–accuracy trade-offs (SATs) are thought to be a fundamental feature of biological information processing, yet most evidence of SATs comes from animals. Here, we examine SATs in the foraging decisions of an acellular, amoeboid organism: the slime mould Physarum polycephalum. Slime moulds were given a simple discrimination task: selecting the highest-quality food item from a set of three options. We investigated the effect of two stressors, light exposure and hunger, on the speed and accur...

  9. Exploring a water/energy trade-off in regional sourcing of livestock feed crops.

    Science.gov (United States)

    Heller, Martin C; Keoleian, Gregory A

    2011-12-15

    Feed production constitutes a major portion of the energy and water resource inputs in modern livestock production. Schemes to reduce these inputs may include local sourcing of animal feed. However, in water stressed regions where irrigation of feed crops is necessary, a trade-off between local sourcing (with high water stress) and transport from less water stressed regions can occur. We demonstrate this trade-off in the U.S. by combining state-level irrigation water use and pumping energy demand from USDA surveys with fertilizer and transportation energy demands for producing major feed crops (corn grain, soybean, alfalfa hay, corn silage) in each state and delivering them to two hypothetical dairy farms located in Kersey, CO and Rosendale, WI. A back-up technology approach is employed to express freshwater resource depletion in units of energy, allowing direct comparison with other energy resource demands. Corn grain, soybean, and alfalfa hay delivered to CO demonstrate a clear trade-off between transportation energy (proportional to the distance between CO and the production state) and water stress. On the other hand, transportation burdens dominate for corn silage, making local production most attractive, even in water stressed regions. All crops delivered to WI (a region of low water stress and minimal irrigation) are dominated by transportation burdens, making local production preferable, but this is clearly not a universal principal, as other cases show. This paper quantitatively elucidates the water-energy trade-off in sourcing feed for livestock and the method is expected to be applicable in managing supply chain logistics of other farm commodities. PMID:22044120

  10. Metabolic Trade-offs in Yeast are Caused by F1F0-ATP synthase

    Science.gov (United States)

    Nilsson, Avlant; Nielsen, Jens

    2016-01-01

    Intermediary metabolism provides living cells with free energy and precursor metabolites required for synthesizing proteins, lipids, RNA and other cellular constituents, and it is highly conserved among living species. Only a fraction of cellular protein can, however, be allocated to enzymes of intermediary metabolism and consequently metabolic trade-offs may take place. One such trade-off, aerobic fermentation, occurs in both yeast (the Crabtree effect) and cancer cells (the Warburg effect) and has been a scientific challenge for decades. Here we show, using flux balance analysis combined with in vitro measured enzyme specific activities, that fermentation is more catalytically efficient than respiration, i.e. it produces more ATP per protein mass. And that the switch to fermentation at high growth rates therefore is a consequence of a high ATP production rate, provided by a limited pool of enzymes. The catalytic efficiency is also higher for cells grown on glucose compared to galactose and ethanol, which may explain the observed differences in their growth rates. The enzyme F1F0-ATP synthase (Complex V) was found to have flux control over respiration in the model, and since it is evolutionary conserved, we expect the trade-off to occur in organisms from all kingdoms of life. PMID:26928598

  11. Faster reproductive rates trade off against offspring growth in wild chimpanzees.

    Science.gov (United States)

    Emery Thompson, Melissa; Muller, Martin N; Sabbi, Kris; Machanda, Zarin P; Otali, Emily; Wrangham, Richard W

    2016-07-12

    Life history theory predicts a trade-off between offspring quality and quantity. Among large-bodied mammals, prolonged lactation and infant dependence suggest particularly strong potential for a quality-quantity trade-off to exist. Humans are one of the only such species to have been examined, providing mixed evidence under a peculiar set of circumstances, including extensive nutritional provisioning by nonmothers and extrasomatic wealth transmission. Here, we examine trade-offs between reproductive rate and one aspect of offspring quality (body size) in wild chimpanzees (Pan troglodytes schweinfurthii), a species with long periods of infant dependence and little direct provisioning. Juvenile lean body mass, estimated using urinary creatinine excretion, was positively associated with the interval to the next sibling's birth. These effects persisted into adolescence and were not moderated by maternal identity. Maternal depletion could not explain poor offspring growth, as older mothers had larger offspring, and low maternal energy balance during lactation predicted larger, not smaller, juvenile size. Instead, our data suggest that offspring growth suffers when mothers wean early to invest in new reproductive efforts. These findings indicate that chimpanzee mothers with the resources to do so prioritize production of new offspring over prolonged investment in current offspring. PMID:27354523

  12. Are there genetic trade-offs between immune and reproductive investments in Tribolium castaneum?

    Science.gov (United States)

    Hangartner, Sandra; Sbilordo, Sonja H; Michalczyk, Łukasz; Gage, Matthew J G; Martin, Oliver Y

    2013-10-01

    Parasites impose strong selection on hosts to defend themselves, which is expected to result in trade-offs with other fitness traits such as reproduction. Here we test for genetic trade-offs between reproductive traits and immunity using Tribolium castaneum lines that were subject to experimental evolution. The lines have been exposed to contrasting sexual selection intensities via different sex ratios (female-biased, equal and male-biased). After 56 generations, the lines have significantly diverged and those experiencing high sexual selection have evolved males who are superior competitors for reproductive success, and females who are more resistant to multiple mating. All selected lines were assessed for both an immune measurement (phenoloxidase (PO) activity) and host resistance to the microsporidian Nosema whitei after two generations of relaxed selection. In contrast to our expectations we did not find any evidence for a genetic trade-off between investment in reproduction and immunity. Both PO and Nosema resistance did not differ between lines, despite their divergences in reproductive investment due to variation in sexual selection and conflict. Nevertheless, overall we found that females had higher PO activities and in the Nosema free control treatment survived longer than males, suggesting that females generally invest more in PO and survival under control conditions than males. This result fits the Bateman's principle, which states that females gain fitness through increased immunity and longevity, while males gain fitness through increased mating success.

  13. No allocation trade-offs between flowering and sproutingin the lignotuberous, Mediterranean shrub Erica australis

    Science.gov (United States)

    Cruz, Alberto; Moreno, José M.

    2001-04-01

    Trade-offs between allocation to sexual or vegetative regeneration capacity are well established as a driving force in the life history patterns of plants in fire-prone environments. However, it is not known whether such trade-offs exist in plants which after aboveground removing disturbances, such as fire, may regenerate by sexual (seeding) or asexual (sprouting) mechanisms. We evaluated whether in the fire-recruiting resprouter Erica australis, which after fire can regenerate by seedling establishment or resprouting, a larger investment in flowers and seeds prior to being disturbed by clipping its aboveground parts would decrease subsequent sprouting, that is, its vegetative regeneration capacity. We analysed the relationships between flower and seed production and the ensuing production and growth of sprouts of six plants from thirteen different sites in central-western Spain. We found no significant relationships between measures of sexual reproductive effort and resprout production and growth 6 months after clipping the aboveground parts of the plants. No evidence of trade-offs between sexual and asexual efforts was found. Furthermore, no significant relationship was found between lignotuber total non-structural carbohydrates and sexual reproductive effort. In addition, 2 years after the disturbance, resprout biomass was positively and significantly correlated with sexual reproductive effort prior to the disturbance. This indicates that growth of resprouts was higher at the sites where plants made a greater reproductive effort. The sites that were more favourable to producing flowers and seeds could also be more favourable to resprouting.

  14. Soil management shapes ecosystem service provision and trade-offs in agricultural landscapes.

    Science.gov (United States)

    Tamburini, Giovanni; De Simone, Serena; Sigura, Maurizia; Boscutti, Francesco; Marini, Lorenzo

    2016-08-31

    Agroecosystems are principally managed to maximize food provisioning even if they receive a large array of supporting and regulating ecosystem services (ESs). Hence, comprehensive studies investigating the effects of local management and landscape composition on the provision of and trade-offs between multiple ESs are urgently needed. We explored the effects of conservation tillage, nitrogen fertilization and landscape composition on six ESs (crop production, disease control, soil fertility, water quality regulation, weed and pest control) in winter cereals. Conservation tillage enhanced soil fertility and pest control, decreased water quality regulation and weed control, without affecting crop production and disease control. Fertilization only influenced crop production by increasing grain yield. Landscape intensification reduced the provision of disease and pest control. We also found tillage and landscape composition to interactively affect water quality regulation and weed control. Under N fertilization, conventional tillage resulted in more trade-offs between ESs than conservation tillage. Our results demonstrate that soil management and landscape composition affect the provision of several ESs and that soil management potentially shapes the trade-offs between them. PMID:27559064

  15. Many-objective optimization and visual analytics reveal key trade-offs for London's water supply

    Science.gov (United States)

    Matrosov, Evgenii S.; Huskova, Ivana; Kasprzyk, Joseph R.; Harou, Julien J.; Lambert, Chris; Reed, Patrick M.

    2015-12-01

    In this study, we link a water resource management simulator to multi-objective search to reveal the key trade-offs inherent in planning a real-world water resource system. We consider new supplies and demand management (conservation) options while seeking to elucidate the trade-offs between the best portfolios of schemes to satisfy projected water demands. Alternative system designs are evaluated using performance measures that minimize capital and operating costs and energy use while maximizing resilience, engineering and environmental metrics, subject to supply reliability constraints. Our analysis shows many-objective evolutionary optimization coupled with state-of-the art visual analytics can help planners discover more diverse water supply system designs and better understand their inherent trade-offs. The approach is used to explore future water supply options for the Thames water resource system (including London's water supply). New supply options include a new reservoir, water transfers, artificial recharge, wastewater reuse and brackish groundwater desalination. Demand management options include leakage reduction, compulsory metering and seasonal tariffs. The Thames system's Pareto approximate portfolios cluster into distinct groups of water supply options; for example implementing a pipe refurbishment program leads to higher capital costs but greater reliability. This study highlights that traditional least-cost reliability constrained design of water supply systems masks asset combinations whose benefits only become apparent when more planning objectives are considered.

  16. No trade-off between growth rate and temperature stress resistance in four insect species.

    Directory of Open Access Journals (Sweden)

    Isabell Karl

    Full Text Available Although fast growth seems to be generally favored by natural selection, growth rates are rarely maximized in nature. Consequently, fast growth is predicted to carry costs resulting in intrinsic trade-offs. Disentangling such trade-offs is of great ecological importance in order to fully understand the prospects and limitations of growth rate variation. A recent study provided evidence for a hitherto unknown cost of fast growth, namely reduced cold stress resistance. Such relationships could be especially important under climate change. Against this background we here investigate the relationships between individual larval growth rate and adult heat as well as cold stress resistance, using eleven data sets from four different insect species (three butterfly species: Bicyclus anynana, Lycaena tityrus, Pieris napi; one Dipteran species: Protophormia terraenovae. Despite using different species (and partly different populations within species and an array of experimental manipulations (e.g. different temperatures, photoperiods, feeding regimes, inbreeding levels, we were not able to provide any consistent evidence for trade-offs between fast growth and temperature stress resistance in these four insect species.

  17. The life-history trade-off between fertility and child survival.

    Science.gov (United States)

    Lawson, David W; Alvergne, Alexandra; Gibson, Mhairi A

    2012-12-01

    Evolutionary models of human reproduction argue that variation in fertility can be understood as the local optimization of a life-history trade-off between offspring quantity and 'quality'. Child survival is a fundamental dimension of quality in these models as early-life mortality represents a crucial selective bottleneck in human evolution. This perspective is well-rehearsed, but current literature presents mixed evidence for a trade-off between fertility and child survival, and little empirical ground to evaluate how socioecological and individual characteristics influence the benefits of fertility limitation. By compiling demographic survey data, we demonstrate robust negative relationships between fertility and child survival across 27 sub-Saharan African countries. Our analyses suggest this relationship is primarily accounted for by offspring competition for parental investment, rather than by reverse causal mechanisms. We also find that the trade-off increases in relative magnitude as national mortality declines and maternal somatic (height) and extrasomatic (education) capital increase. This supports the idea that socioeconomic development, and associated reductions in extrinsic child mortality, favour reduced fertility by increasing the relative returns to parental investment. Observed fertility, however, falls considerably short of predicted optima for maximizing total offspring survivorship, strongly suggesting that additional unmeasured costs of reproduction ultimately constrain the evolution of human family size. PMID:23034700

  18. Defining Pathways and Trade-offs Toward Universal Health Coverage Comment on “Ethical Perspective: Five Unacceptable Trade-offs on the Path to Universal Health Coverage”

    Directory of Open Access Journals (Sweden)

    Stéphane Verguet

    2016-07-01

    Full Text Available The World Health Organization’s (WHO’s World Health Report 2010, “Health systems financing, the path to universal coverage,” promoted universal health coverage (UHC as an aspirational objective for country health systems. Yet, in addition to the dimensions of services and coverage, distribution of coverage in the population, and financial risk protection highlighted by the report, the consideration of the budget constraint should be further strengthened in the ensuing debate on resource allocation toward UHC. Beyond the substantial financial constraints faced by low- and middle-income countries, additional considerations, such as the geographical context, the underlying country infrastructure, and the architecture of health systems, determine the feasibility, effectiveness, quality and cost of healthcare delivery. Therefore, increased production and use of local evidence tied to the criteria of health benefits, equity, financial risk protection, and costs accompanying health delivery are needed so that to highlight pathways and acceptable trade-offs toward UHC.

  19. Essays on equity-efficiency trade offs in energy and climate policies

    Science.gov (United States)

    Sesmero, Juan P.

    Economic efficiency and societal equity are two important goals of public policy. Energy and climate policies have the potential to affect both. Efficiency is increased by substituting low-carbon energy for fossil energy (mitigating an externality) while equity is served if such substitution enhances consumption opportunities of unfavored groups (low income households or future generations). However policies that are effective in reducing pollution may not be so effective in redistributing consumption and vice-versa. This dissertation explores potential trade-offs between equity and efficiency arising in energy and climate policies. Chapter 1 yields two important results. First, while effective in reducing pollution, energy efficiency policies may fall short in protecting future generations from resource depletion. Second, deployment of technologies that increase the ease with which capital can substitute for energy may enhance the ability of societies to sustain consumption and achieve intertemporal equity. Results in Chapter 1 imply that technologies more intensive in capital and materials and less intensive in carbon such as corn ethanol may be effective in enhancing intertemporal equity. However the effectiveness of corn ethanol (relative to other technologies) in reducing emissions will depend upon the environmental performance of the industry. Chapter 2 measures environmental efficiency of ethanol plants, identifies ways to enhance performance, and calculates the cost of such improvements based on a survey of ethanol plants in the US. Results show that plants may be able to increase profits and reduce emissions simultaneously rendering the ethanol industry more effective in tackling efficiency. Finally while cap and trade proposals are designed to correcting a market failure by reducing pollution, allocation of emission allowances may affect income distribution and, hence, intra-temporal equity. Chapter 3 proves that under plausible conditions on preferences

  20. A trade-off between embryonic development rate and immune function of avian offspring is concealed by embryonic temperature

    Science.gov (United States)

    Martin, Thomas E.; Arriero, Elena; Majewska, Ania

    2011-01-01

    Long embryonic periods are assumed to reflect slower intrinsic development that are thought to trade off to allow enhanced physiological systems, such as immune function. Yet, the relatively rare studies of this trade-off in avian offspring have not found the expected trade-off. Theory and tests have not taken into account the strong extrinsic effects of temperature on embryonic periods of birds. Here, we show that length of the embryonic period did not explain variation in two measures of immune function when temperature was ignored, based on studies of 34 Passerine species in tropical Venezuela (23 species) and north temperate Arizona (11 species). Variation in immune function was explained when embryonic periods were corrected for average embryonic temperature, in order to better estimate intrinsic rates of development. Immune function of offspring trades off with intrinsic rates of embryonic development once the extrinsic effects of embryonic temperatures are taken into account.

  1. Nest Construction by a Ground-nesting Bird Represents a Potential Trade-off Between Egg Crypticity and Thermoregulation

    Science.gov (United States)

    Predation selects against conspicuous colors in bird eggs and nests, while thermoregulatory constraints select for nest building behavior that regulates incubation temperatures. We present results that reveal a trade-off between nest crypticity and thermoregulation of eggs base...

  2. Warmer temperatures attenuate the classic offspring number and reproductive investment trade-off in the common lizard, Zootoca vivipara.

    Science.gov (United States)

    Rutschmann, Alexis; Miles, Donald B; Clobert, Jean; Richard, Murielle

    2016-06-01

    Life-history traits involved in trade-offs are known to vary with environmental conditions. Here, we evaluate the response of the trade-off between 'offspring number' versus 'energy invested per offspring' to ambient temperature in 11 natural populations of the common lizard, Zootoca vivipara We provide evidence at both the intra- and interpopulation levels that the trade-off is reduced with an increase in air temperature. If this effect enhances current individual fitness, it may lead to an accelerated pace of life in warmer environments and could ultimately increase adult mortality. In the context of global warming, our results advocate the need for more studies in natural populations to explore interactions between life-history traits' trade-offs and environmental conditions. PMID:27247438

  3. Navigating trade-offs in land-use planning: integrating human well-being into objective setting

    OpenAIRE

    Vanessa M. Adams; Pressey, Robert L.; Natalie Stoeckl

    2014-01-01

    There is an increasing demand for development of natural resources, which can be accompanied by environmental degradation. Planning for multiple land uses requires navigating trade-offs between social, economic, and environmental outcomes arising from different possible futures. To explore these trade-offs, we use the Daly River catchment, in Australia's Northern Territory, as a case study. The catchment contains areas of priority for both conservation and development. In response to the cha...

  4. French firm's financing choices: towards a reconciliation of the static trade-off theory and the pecking order theory?

    OpenAIRE

    Mazen, Gharsalli

    2011-01-01

    International audience; The main purpose of this study is to examine the validity of the static trade-off theory and the pecking order theory using a French panel data. Our empirical tests provide that we can not formally reject either of the two theories explaining financing behavior. However, they confirm the importance of considerations provided by the static trade-off theory. On the contrary, when we combine the adjustment model and the pecking order model we find that the statistical pow...

  5. Exploring Trade-Offs between Fisheries and Conservation of the Vaquita Porpoise (Phocoena sinus) Using an Atlantis Ecosystem Model

    OpenAIRE

    Hem Nalini Morzaria-Luna; Cameron H Ainsworth; Kaplan, Isaac C.; Levin, Phillip S.; Fulton, Elizabeth A.

    2012-01-01

    BACKGROUND: Minimizing fishery bycatch threats might involve trade-offs between maintaining viable populations and economic benefits. Understanding these trade-offs can help managers reconcile conflicting goals. An example is a set of bycatch reduction measures for the Critically Endangered vaquita porpoise (Phocoena sinus), in the Northern Gulf of California, Mexico. The vaquita is an endemic species threatened with extinction by artisanal net bycatch within its limited range; in this area f...

  6. Haste Makes Waste but Condition Matters: Molt Rate-Feather Quality Trade-Off in a Sedentary Songbird

    OpenAIRE

    Csongor I Vágási; Pap, Péter L.; Orsolya Vincze; Zoltán Benkő; Attila Marton; Zoltán Barta

    2012-01-01

    BACKGROUND: The trade-off between current and residual reproductive values is central to life history theory, although the possible mechanisms underlying this trade-off are largely unknown. The 'molt constraint' hypothesis suggests that molt and plumage functionality are compromised by the preceding breeding event, yet this candidate mechanism remains insufficiently explored. METHODOLOGY/PRINCIPAL FINDINGS: The seasonal change in photoperiod was manipulated to accelerate the molt rate. This t...

  7. Incest versus abstinence: reproductive trade-offs between mate limitation and progeny fitness in a self-incompatible invasive plant

    OpenAIRE

    Pierson, Jennifer C; Swain, Stephen M; Young, Andrew G

    2013-01-01

    Plant mating systems represent an evolutionary and ecological trade-off between reproductive assurance through selfing and maximizing progeny fitness through outbreeding. However, many plants with sporophytic self-incompatibility systems exhibit dominance interactions at the S-locus that allow biparental inbreeding, thereby facilitating mating between individuals that share alleles at the S-locus. We investigated this trade-off by estimating mate availability and biparental inbreeding depress...

  8. Adaptive trade-off in C. capitata is a characteristic feature of the long-lived subpopulation

    OpenAIRE

    Alexei Romanioukha; Arseniy S. Karkach; Carey, James R.; Yashin, Anatoli I

    2010-01-01

    The conception of the cost of reproduction provides an important insight on connection between fertility and life span in living organisms. Despite substantial progress in understanding this connection many important features of fertility-longevity trade-off are masked by confounding factors, and remain poorly understood. We performed reanalysis of experimental data on fertility and longevity in medflies and discovered a physiological fertility-longevity trade-off especially pronounced in the...

  9. Can number and size of offspring increase simultaneously? - a central life-history trade-off reconsidered

    OpenAIRE

    Schroderus Eero; Koivula Minna; Koskela Esa; Mappes Tapio; Oksanen Tuula A; Poikonen Tanja

    2012-01-01

    Abstract Background To maximize their fitness, parents are assumed to allocate their resources optimally between number and size of offspring. Although this fundamental life-history trade-off has been subject to long standing interest, its genetic basis, especially in wild mammals, still remains unresolved. One important reason for this problem is that a large multigenerational pedigree is required to conduct a reliable analysis of this trade-off. Results We used the REML-animal model to esti...

  10. The role of trade-offs in biodiversity conservation planning: linking local management, regional planning and global conservation efforts

    Indian Academy of Sciences (India)

    Daniel P Faith; P A Walker

    2002-07-01

    Biodiversity conservation planning requires trade-offs, given the realities of limited resources and the competing demands of society. If net benefits for society are important, biodiversity assessment cannot occur without other sectoral factors ``on the table”. In trade-offs approaches, the biodiversity value of a given area is expressed in terms of the species or other components of biodiversity that it has that are additional to the components protected elsewhere. That ``marginal gain” is called the complementarity value of the area. A recent whole-country planning study for Papua New Guinea illustrates the importance of complementarity-based trade-offs in determining priority areas for biodiversity conservation, and for designing economic instruments such as biodiversity levies and offsets. Two international biodiversity programs provide important new opportunities for biodiversity trade-offs taking complementarity into account. Both the Millennium Ecosystem Assessment and the Critical Ecosystems or ``hotspots” programs can benefit from an explicit framework that incorporates trade-offs, in which a balance is achieved not only by land-use allocation among areas, but also by the crediting of partial protection of biodiversity provided by sympathetic management within areas. For both international programs, our trade-offs framework can provide a natural linkage between local, regional and global planning levels.

  11. Testing the competition-colonization trade-off with a 32-year study of a saxicolous lichen community.

    Science.gov (United States)

    Pastore, A I; Prather, C M; Gornish, E S; Ryan, W H; Ellis, R D; Milleri, T E

    2014-02-01

    Competition-colonization trade-offs are theorized to be a mechanism of coexistence in communities structured by environmental fluctuations. But many studies that have tested for the trade-off have failed to detect it, likely because a spatiotemporally structured environment and many species assemblages are needed to adequately test for a competition-colonization trade-off. Here, we present a unique 32-year study of rock-dwelling lichens in New Mexico, USA, in which photographs were used to quantify lichen life history traits and interactions through time. These data allowed us to determine whether there were any trade-offs between traits associated with colonization and competition, as well as the relationship between diversity and disturbance in the community. We did not find evidence for a trade-off between competitive ability and colonization rate or any related life history traits. Interestingly, we did find a peak in all measures of species diversity at intermediate levels of disturbance, consistent with the intermediate disturbance hypothesis pattern. We suggest that the coexistence of the dominant species in this system is regulated by differences in persistence and growth rate mediating overgrowth competition rather than a competition-colonization trade-off. PMID:24669725

  12. Can number and size of offspring increase simultaneously? - a central life-history trade-off reconsidered

    Directory of Open Access Journals (Sweden)

    Schroderus Eero

    2012-03-01

    Full Text Available Abstract Background To maximize their fitness, parents are assumed to allocate their resources optimally between number and size of offspring. Although this fundamental life-history trade-off has been subject to long standing interest, its genetic basis, especially in wild mammals, still remains unresolved. One important reason for this problem is that a large multigenerational pedigree is required to conduct a reliable analysis of this trade-off. Results We used the REML-animal model to estimate genetic parameters for litter size and individual birth size for a common Palearctic small mammal, the bank vole (Myodes glareolus. Even though a phenotypic trade-off between offspring number and size was evident, it was not explained by a genetic trade-off, but rather by negative correlations in permanent and temporary environmental effects. In fact, even positive genetic correlations were estimated between direct genetic effects for offspring number and size indicating that genetic variation in these two traits is not necessarily antagonistic in mammals. Conclusions Our results have notable implications for the study of the life-history trade-off between offspring number and size in mammals. The estimated genetic correlations suggest that evolution of offspring number and size in polytocous mammals is not constrained by the trade-off caused by antagonistic selection responses per se, but rather by the opposing correlative selection responses in direct and maternal genetic effects for birth size.

  13. Trade-offs and evolution of thermal adaptation in the Irish potato famine pathogen Phytophthora infestans.

    Science.gov (United States)

    Yang, Li-Na; Zhu, Wen; Wu, E-Jiao; Yang, Ce; Thrall, Peter H; Burdon, Jeremy J; Jin, Li-Ping; Shang, Li-Ping; Zhan, Jiasui

    2016-08-01

    Temperature is one of the most important environmental parameters with crucial impacts on nearly all biological processes. Due to anthropogenic activity, average air temperatures are expected to increase by a few degrees in coming decades, accompanied by an increased occurrence of extreme temperature events. Such global trends are likely to have various major impacts on human society through their influence on natural ecosystems, food production and biotic interactions, including diseases. In this study, we used a combination of statistical genetics, experimental evolution and common garden experiments to investigate the evolutionary potential for thermal adaptation in the potato late blight pathogen, Phytophthora infestans, and infer its likely response to changing temperatures. We found a trade-off associated with thermal adaptation to heterogeneous environments in P. infestans, with the degree of the trade-off peaking approximately at the pathogen's optimum growth temperature. A genetic trade-off in thermal adaptation was also evidenced by the negative association between a strain's growth rate and its thermal range for growth, and warm climates selecting for a low pathogen growth rate. We also found a mirror effect of phenotypic plasticity and genetic adaptation on growth rate. At below the optimum, phenotypic plasticity enhances pathogen's growth rate but nature selects for slower growing genotypes when temperature increases. At above the optimum, phenotypic plasticity reduces pathogen's growth rate but natural selection favours for faster growing genotypes when temperature increases further. We conclude from these findings that the growth rate of P. infestans will only be marginally affected by global warming. PMID:27288627

  14. Chronic inflammatory systemic diseases: An evolutionary trade-off between acutely beneficial but chronically harmful programs.

    Science.gov (United States)

    Straub, Rainer H; Schradin, Carsten

    2016-01-01

    It has been recognized that during chronic inflammatory systemic diseases (CIDs) maladaptations of the immune, nervous, endocrine and reproductive system occur. Maladaptation leads to disease sequelae in CIDs. The ultimate reason of disease sequelae in CIDs remained unclear because clinicians do not consider bodily energy trade-offs and evolutionary medicine. We review the evolution of physiological supersystems, fitness consequences of genes involved in CIDs during different life-history stages, environmental factors of CIDs, energy trade-offs during inflammatory episodes and the non-specificity of CIDs. Incorporating bodily energy regulation into evolutionary medicine builds a framework to better understand pathophysiology of CIDs by considering that genes and networks used are positively selected if they serve acute, highly energy-consuming inflammation. It is predicted that genes that protect energy stores are positively selected (as immune memory). This could explain why energy-demanding inflammatory episodes like infectious diseases must be terminated within 3-8 weeks to be adaptive, and otherwise become maladaptive. Considering energy regulation as an evolved adaptive trait explains why many known sequelae of different CIDs must be uniform. These are, e.g. sickness behavior/fatigue/depressive symptoms, sleep disturbance, anorexia, malnutrition, muscle wasting-cachexia, cachectic obesity, insulin resistance with hyperinsulinemia, dyslipidemia, alterations of steroid hormone axes, disturbances of the hypothalamic-pituitary-gonadal (HPG) axis, hypertension, bone loss and hypercoagulability. Considering evolved energy trade-offs helps us to understand how an energy imbalance can lead to the disease sequelae of CIDs. In the future, clinicians must translate this knowledge into early diagnosis and symptomatic treatment in CIDs. PMID:26817483

  15. No evidence for a trade-off between reproductive investment and immunity in a rodent.

    Directory of Open Access Journals (Sweden)

    Yan-Chao Xu

    Full Text Available Life history theory assumes there are trade-offs between competing functions such as reproduction and immunity. Although well studied in birds, studies of the trade-offs between reproduction and immunity in small mammals are scarce. Here we examined whether reduced immunity is a consequence of reproductive effort in lactating Brandt's voles (Lasiopodomys brandtii. Specifically, we tested the effects of lactation on immune function (Experiment I. The results showed that food intake and resting metabolic rate (RMR were higher in lactating voles (6≤ litter size ≤8 than that in non-reproductive voles. Contrary to our expectation, lactating voles also had higher levels of serum total Immunoglobulin G (IgG and anti-keyhole limpet hemocyanin (KLH IgG and no change in phytohemagglutinin (PHA response and anti-KLH Immunoglobulin M (IgM compared with non-reproductive voles, suggesting improved rather than reduced immune function. To further test the effect of differences in reproductive investment on immunity, we compared the responses between natural large (n≥8 and small litter size (n≤6 (Experiment II and manipulated large (11-13 and small litter size (2-3 (Experiment III. During peak lactation, acquired immunity (PHA response, anti-KLH IgG and anti-KLH IgM was not significantly different between voles raising large or small litters in both experiments, despite the measured difference in reproductive investment (greater litter size, litter mass, RMR and food intake in the voles raising larger litters. Total IgG was higher in voles with natural large litter size than those with natural small litter size, but decreased in the enlarged litter size group compared with control and reduced group. Our results showed that immune function is not suppressed to compensate the high energy demands during lactation in Brandt's voles and contrasting the situation in birds, is unlikely to be an important aspect mediating the trade-off between reproduction and

  16. Assessing social--ecological trade-offs to advance ecosystem-based fisheries management.

    Directory of Open Access Journals (Sweden)

    Rudi Voss

    Full Text Available Modern resource management faces trade-offs in the provision of various ecosystem goods and services to humanity. For fisheries management to develop into an ecosystem-based approach, the goal is not only to maximize economic profits, but to consider equally important conservation and social equity goals. We introduce such a triple-bottom line approach to the management of multi-species fisheries using the Baltic Sea as a case study. We apply a coupled ecological-economic optimization model to address the actual fisheries management challenge of trading-off the recovery of collapsed cod stocks versus the health of ecologically important forage fish populations. Management strategies based on profit maximization would rebuild the cod stock to high levels but may cause the risk of stock collapse for forage species with low market value, such as Baltic sprat (Fig. 1A. Economically efficient conservation efforts to protect sprat would be borne almost exclusively by the forage fishery as sprat fishing effort and profits would strongly be reduced. Unless compensation is paid, this would challenge equity between fishing sectors (Fig. 1B. Optimizing equity while respecting sprat biomass precautionary levels would reduce potential profits of the overall Baltic fishery, but may offer an acceptable balance between overall profits, species conservation and social equity (Fig. 1C. Our case study shows a practical example of how an ecosystem-based fisheries management will be able to offer society options to solve common conflicts between different resource uses. Adding equity considerations to the traditional trade-off between economy and ecology will greatly enhance credibility and hence compliance to management decisions, a further footstep towards healthy fish stocks and sustainable fisheries in the world ocean.

  17. Assessing social--ecological trade-offs to advance ecosystem-based fisheries management.

    Science.gov (United States)

    Voss, Rudi; Quaas, Martin F; Schmidt, Jörn O; Tahvonen, Olli; Lindegren, Martin; Möllmann, Christian

    2014-01-01

    Modern resource management faces trade-offs in the provision of various ecosystem goods and services to humanity. For fisheries management to develop into an ecosystem-based approach, the goal is not only to maximize economic profits, but to consider equally important conservation and social equity goals. We introduce such a triple-bottom line approach to the management of multi-species fisheries using the Baltic Sea as a case study. We apply a coupled ecological-economic optimization model to address the actual fisheries management challenge of trading-off the recovery of collapsed cod stocks versus the health of ecologically important forage fish populations. Management strategies based on profit maximization would rebuild the cod stock to high levels but may cause the risk of stock collapse for forage species with low market value, such as Baltic sprat (Fig. 1A). Economically efficient conservation efforts to protect sprat would be borne almost exclusively by the forage fishery as sprat fishing effort and profits would strongly be reduced. Unless compensation is paid, this would challenge equity between fishing sectors (Fig. 1B). Optimizing equity while respecting sprat biomass precautionary levels would reduce potential profits of the overall Baltic fishery, but may offer an acceptable balance between overall profits, species conservation and social equity (Fig. 1C). Our case study shows a practical example of how an ecosystem-based fisheries management will be able to offer society options to solve common conflicts between different resource uses. Adding equity considerations to the traditional trade-off between economy and ecology will greatly enhance credibility and hence compliance to management decisions, a further footstep towards healthy fish stocks and sustainable fisheries in the world ocean.

  18. The Utility of Seasonal Climate Forecasts: Understanding Argentine Farmers' Attribute Priorities and Trade-Offs

    Science.gov (United States)

    Seipt, E. C.; Easterling, W. E.

    2007-05-01

    A distinct El Niño - Southern Oscillation (ENSO) signal and its impacts have been confirmed in the Argentine Pampas, and precipitation variability is currently recognized as the region's most marked ENSO-driven influence. In the Pampas, precipitation is also a major limiting factor for agricultural production given spatial differences in soil water storage capacities and the region's relatively minimal use of irrigation. Seasonal climate forecasts that provide advanced knowledge of expected ENSO-driven precipitation anomalies may benefit farm management decision-making by helping to either mitigate potentially negative consequences or to take advantage of potentially positive influences. To be useful and applicable, however, these forecasts must suit the decisions that they are meant to inform. In this research, a case study is presented that investigates how farmers in the Pampas prioritize and trade off specific attributes of a seasonal climate forecast (i.e., mode of distribution, spatial resolution, lead time, and forecast performance) when judging its utility. A conjoint analysis evaluation decomposes holistic evaluations of forecasts into the part-worth utilities associated with their different attributes. Part-worth utilities combine to reveal the structure of farmers' forecast utility preferences - a model of the decision-making process. Utility preference structures are analyzed to compute the importance value of each attribute and to determine the trade-offs that farmers find acceptable between different attributes. Analysis indicates that, on average, spatial resolution is the most influential attribute in determining climate forecast utility. Attribute trade-off values suggest that advances in spatial resolution, forecast performance, and/or product dissemination via the Internet offer the greatest potential for increasing the utility of future seasonal climate forecasts for farmers in the Pampas.

  19. Assessing social--ecological trade-offs to advance ecosystem-based fisheries management.

    Science.gov (United States)

    Voss, Rudi; Quaas, Martin F; Schmidt, Jörn O; Tahvonen, Olli; Lindegren, Martin; Möllmann, Christian

    2014-01-01

    Modern resource management faces trade-offs in the provision of various ecosystem goods and services to humanity. For fisheries management to develop into an ecosystem-based approach, the goal is not only to maximize economic profits, but to consider equally important conservation and social equity goals. We introduce such a triple-bottom line approach to the management of multi-species fisheries using the Baltic Sea as a case study. We apply a coupled ecological-economic optimization model to address the actual fisheries management challenge of trading-off the recovery of collapsed cod stocks versus the health of ecologically important forage fish populations. Management strategies based on profit maximization would rebuild the cod stock to high levels but may cause the risk of stock collapse for forage species with low market value, such as Baltic sprat (Fig. 1A). Economically efficient conservation efforts to protect sprat would be borne almost exclusively by the forage fishery as sprat fishing effort and profits would strongly be reduced. Unless compensation is paid, this would challenge equity between fishing sectors (Fig. 1B). Optimizing equity while respecting sprat biomass precautionary levels would reduce potential profits of the overall Baltic fishery, but may offer an acceptable balance between overall profits, species conservation and social equity (Fig. 1C). Our case study shows a practical example of how an ecosystem-based fisheries management will be able to offer society options to solve common conflicts between different resource uses. Adding equity considerations to the traditional trade-off between economy and ecology will greatly enhance credibility and hence compliance to management decisions, a further footstep towards healthy fish stocks and sustainable fisheries in the world ocean. PMID:25268117

  20. Assessing Social – Ecological Trade-Offs to Advance Ecosystem-Based Fisheries Management

    Science.gov (United States)

    Voss, Rudi; Quaas, Martin F.; Schmidt, Jörn O.; Tahvonen, Olli; Lindegren, Martin; Möllmann, Christian

    2014-01-01

    Modern resource management faces trade-offs in the provision of various ecosystem goods and services to humanity. For fisheries management to develop into an ecosystem-based approach, the goal is not only to maximize economic profits, but to consider equally important conservation and social equity goals. We introduce such a triple-bottom line approach to the management of multi-species fisheries using the Baltic Sea as a case study. We apply a coupled ecological-economic optimization model to address the actual fisheries management challenge of trading-off the recovery of collapsed cod stocks versus the health of ecologically important forage fish populations. Management strategies based on profit maximization would rebuild the cod stock to high levels but may cause the risk of stock collapse for forage species with low market value, such as Baltic sprat (Fig. 1A). Economically efficient conservation efforts to protect sprat would be borne almost exclusively by the forage fishery as sprat fishing effort and profits would strongly be reduced. Unless compensation is paid, this would challenge equity between fishing sectors (Fig. 1B). Optimizing equity while respecting sprat biomass precautionary levels would reduce potential profits of the overall Baltic fishery, but may offer an acceptable balance between overall profits, species conservation and social equity (Fig. 1C). Our case study shows a practical example of how an ecosystem-based fisheries management will be able to offer society options to solve common conflicts between different resource uses. Adding equity considerations to the traditional trade-off between economy and ecology will greatly enhance credibility and hence compliance to management decisions, a further footstep towards healthy fish stocks and sustainable fisheries in the world ocean. PMID:25268117

  1. Carbon allocation during defoliation: testing a defence-growth trade-off in balsam fir

    Directory of Open Access Journals (Sweden)

    Annie eDeslauriers

    2015-05-01

    Full Text Available During repetitive defoliation events, carbon can become limiting for trees. To maintain growth and survival, the resources have to be shared more efficiently, which could result in a trade-off between the different physiological processes of a plant. The objective of this study was to assess the effect of defoliation in carbon allocation of balsam fir [Abies balsamea (L. Mill.] to test the presence of a trade-off between allocation to growth, carbon storage and defence. Three defoliation intensities [control (C-trees, 0% defoliation, moderately (M-trees, 41 to 60% and heavily (H-trees, 61 to 80% defoliated] were selected in order to monitor several variables related to stem growth (wood formation in xylem, carbon storage in stem and needle (non-structural soluble sugars and starch and defence components in needles (terpenoids compound from May to October 2011. The concentration of starch was drastically reduced in both wood and leaves of H-trees with a quasi-absence of carbon partitioning to storage in early summer. Fewer kinds of monoterpenes and sesquiterpenes were formed with an increasing level of defoliation indicating a lower carbon allocation for the production of defence. The carbon allocation to wood formation gradually reduced at increasing defoliation intensities, with a lower growth rate and fewer tracheids resulting in a reduced carbon sequestration in cell walls. The hypothesis of a trade-off between the allocations to defence components and to non-structural (NCS and structural (growth carbon was rejected as most of the measured variables decreased with increasing defoliation. The starch amount was highly indicative of the tree carbon status at different defoliation intensity and future research should focus on the mechanism of starch utilisation for survival and growth following an outbreak.

  2. Carbon allocation during defoliation: testing a defense-growth trade-off in balsam fir

    Science.gov (United States)

    Deslauriers, Annie; Caron, Laurie; Rossi, Sergio

    2015-01-01

    During repetitive defoliation events, carbon can become limiting for trees. To maintain growth and survival, the resources have to be shared more efficiently, which could result in a trade-off between the different physiological processes of a plant. The objective of this study was to assess the effect of defoliation in carbon allocation of balsam fir [Abies balsamea (L.) Mill.] to test the presence of a trade-off between allocation to growth, carbon storage, and defense. Three defoliation intensities [control (C-trees, 0% defoliation), moderately (M-trees, 41–60%), and heavily (H-trees, 61–80%) defoliated] were selected in order to monitor several variables related to stem growth (wood formation in xylem), carbon storage in stem and needle (non-structural soluble sugars and starch), and defense components in needles (terpenoids compound) from May to October 2011. The concentration of starch was drastically reduced in both wood and leaves of H-trees with a quasi-absence of carbon partitioning to storage in early summer. Fewer kinds of monoterpenes and sesquiterpenes were formed with an increasing level of defoliation indicating a lower carbon allocation for the production of defense. The carbon allocation to wood formation gradually reduced at increasing defoliation intensities, with a lower growth rate and fewer tracheids resulting in a reduced carbon sequestration in cell walls. The hypothesis of a trade-off between the allocations to defense components and to non-structural (NCS) and structural (growth) carbon was rejected as most of the measured variables decreased with increasing defoliation. The starch amount was highly indicative of the tree carbon status at different defoliation intensity and future research should focus on the mechanism of starch utilization for survival and growth following an outbreak. PMID:26029235

  3. Loss of adaptation following reversion suggests trade-offs in host use by a seed beetle.

    Science.gov (United States)

    Messina, F J; Durham, S L

    2015-10-01

    Experimental evolution has provided little support for the hypothesis that the narrow diets of herbivorous insects reflect trade-offs in performance across hosts; selection lines can sometimes adapt to an inferior novel host without a decline in performance on the ancestral host. An alternative approach for detecting trade-offs would be to measure adaptation decay after selection is relaxed, that is, when populations newly adapted to a novel host are reverted to the ancestral one. Lines of the seed beetle Callosobruchus maculatus rapidly adapted to a poor host (lentil); survival in lentil seeds increased from 2% to > 90% in lentil, sublines were reverted to the ancestral host, mung bean. Twelve generations of reversion had little effect on performance in lentil, but after 25-35 generations, the reverted lines exhibited lower survival, slower development and smaller size. The most divergent pair of lines was then assayed on both lentil and mung bean. Performance on lentil was again much poorer in the reverted line than in the nonreverted one, but the lines performed equally well on mung bean. Moreover, the performance of the nonreverted line on mung bean remained comparable to that of the original mung-bean population. Our results thus present a paradox: loss of adaptation to lentil following reversion implies a trade-off, but the continued strong performance of lentil-adapted lines on mung bean does not. Genomic comparisons of the reverted, nonreverted and ancestral lines may resolve this paradox and determine the importance of selection vs. drift in causing a loss of adaptation following reversion. PMID:26201813

  4. Trade-offs between xylem hydraulic properties, wood anatomy and yield in Populus.

    Science.gov (United States)

    Hajek, Peter; Leuschner, Christoph; Hertel, Dietrich; Delzon, Sylvain; Schuldt, Bernhard

    2014-07-01

    Trees face the dilemma that achieving high plant productivity is accompanied by a risk of drought-induced hydraulic failure due to a trade-off in the trees' vascular system between hydraulic efficiency and safety. By investigating the xylem anatomy of branches and coarse roots, and measuring branch axial hydraulic conductivity and vulnerability to cavitation in 4-year-old field-grown aspen plants of five demes (Populus tremula L. and Populus tremuloides Michx.) differing in growth rate, we tested the hypotheses that (i) demes differ in wood anatomical and hydraulic properties, (ii) hydraulic efficiency and safety are related to xylem anatomical traits, and (iii) aboveground productivity and hydraulic efficiency are negatively correlated to cavitation resistance. Significant deme differences existed in seven of the nine investigated branch-related anatomical and hydraulic traits but only in one of the four coarse-root-related anatomical traits; this likely is a consequence of high intra-plant variation in root morphology and the occurrence of a few 'high-conductivity roots'. Growth rate was positively related to branch hydraulic efficiency (xylem-specific conductivity) but not to cavitation resistance; this indicates that no marked trade-off exists between cavitation resistance and growth. Both branch hydraulic safety and hydraulic efficiency significantly depended on vessel size and were related to the genetic distance between the demes, while the xylem pressure causing 88% loss of hydraulic conductivity (P88 value) was more closely related to hydraulic efficiency than the commonly used P50 value. Deme-specific variation in the pit membrane structure may explain why vessel size was not directly linked to growth rate. We conclude that branch hydraulic efficiency is an important growth-influencing trait in aspen, while the assumed trade-off between productivity and hydraulic safety is weak.

  5. A Reference-Dependent Regret Model for Deterministic Trade-off Studies

    Energy Technology Data Exchange (ETDEWEB)

    Kujawski, Edouard

    2005-02-25

    Today's typical multi-criteria decision analysis is based on classical expected utility theory that assumes a mythical ''Rational Individual'' immune to psychological influences such as anticipated regret. It is therefore in conflict with rational individuals who trade-off some benefits and forgo the alternative with the highest total classical utility for a more balanced alternative in order to reduce their levels of anticipated regret. This paper focuses on decision making under certainty. It presents a reference-dependent regret model (RDRM) in which the level of regret that an individual experiences depends on the absolute values rather than the differences of the utilities of the chosen and forgone alternatives. The RDRM best choice may differ from the conventional linear additive utility model, the analytic hierarchy process, and the regret theory of Bell and Loomes and Sugden. Examples are presented that indicate that RDRM is the better predictive descriptor for decision making under certainty. RDRM satisfies transitivity of the alternatives under pairwise comparisons and models rank reversal consistent with observed reasonable choices under dynamic or distinct situations. Like regret theory, the RDRM utilities of all the alternatives under consideration are interrelated. For complex trade-off studies regret is incorporated as an element of a cost-utility-regret analysis that characterizes each alternative in terms of its monetary cost, an aggregate performance utility, and a regret value. This provides decision makers adequate information to compare the alternatives and depending on their values they may trade-off some performance and/or cost to avoid high levels of regret. The result is a well-balanced alternative often preferred by reasonable decision makers to the optimal choice of classical multi-attribute utility analysis. The model can readily be extended to incorporate rejoicing to suit decision makers who seek it. The

  6. The Trade-Off between Housing and Pensions in the Household Portfolio of the Eldery

    OpenAIRE

    Müller, T. (Tessa)

    2015-01-01

    Both household investments in own housing and payments into the pension system are forms of a life-cycle redistribution process of income from working age to retirement. They can be seen as a store of wealth that can be released in the old-age. There is a already well-established theory about a possible trade-off between both income forms or more generally speaking between home ownership and the development of the welfare state. This paper adds to the existing literature by estimating the off...

  7. Science Requirements and Trade-offs for the MOSAIC Instrument for the European ELT

    CERN Document Server

    Evans, C J; Rodrigues, M; Barbuy, B; Cuby, J -G; Dalton, G; Fitzsimons, E; Hammer, F; Jagourel, P; Kaper, L; Morris, S L; Morris, T J

    2016-01-01

    Building on the comprehensive White Paper on the scientific case for multi-object spectroscopy on the European ELT, we present the top-level instrument requirements that are being used in the Phase A design study of the MOSAIC concept. The assembled cases span the full range of E-ELT science and generally require either 'high multiplex' or 'high definition' observations to best exploit the excellent sensitivity and spatial performance of the telescope. We highlight some of the science studies that are now being used in trade-off studies to inform the capabilities of MOSAIC and its technical design.

  8. The Risk-Return Trade-Off in Human Capital Investment

    DEFF Research Database (Denmark)

    Christiansen, Charlotte; Joensen, Juanna Schrøter; Nielsen, Helena Skyt

    In this paper we analyze investments in human capital assets in a way which is standard for financial assets, but not (yet) for human capital assets. We study mean-variance plots of human capital assets. We compare the properties of human capital returns using a performance measure and by sing...... tests for mean-variance spanning. A risk-return trade-off is revealed, hich is not only related to the length of education but also to the type of education. We identify a range of educations that are efficient in terms of investment goods, and a range of educations that are inefficient, and may...

  9. Size, gain and bandwidth trade-offs for wideband diamond dipole with AMC reflector

    Science.gov (United States)

    Joshi, Chetan; Lepage, Anne Claire; Sarrazin, Julien; Begaud, Xavier

    2016-03-01

    Compact and directive ultra-wideband antennas are required in variety of applications. Directional wideband antennas can be designed by using a reflector to redirect the energy back in half space and increase the gain. Use of artificial magnetic conductors (AMC) as reflectors for antennas allows reduction in the thickness of an antenna using traditional perfect electrical conductors (PEC) reflectors. The lateral size of the reflector also has an important effect on the antenna performance. In this paper, we study the trade-offs involved in the design of an AMC used as a reflector for broadband diamond dipole antenna by simulating various sizes of the reflector.

  10. Introducing the composite time trade-off: a test of feasibility and face validity

    OpenAIRE

    Janssen, Bas M. F.; Oppe, Mark; Versteegh, Matthijs M.; Stolk, Elly A.

    2013-01-01

    Introduction This study was designed to test the feasibility and face validity of the composite time trade-off (composite TTO), a new approach to TTO allowing for a more consistent elicitation of negative health state values. Methods The new instrument combines a conventional TTO to elicit values for states regarded better than dead and a lead-time TTO for states worse than dead. Results A total of 121 participants completed the composite TTO for ten EQ-5D-5L health states. Mean values ranged...

  11. Trade-off between Linewidth and Slip Rate in a Mode-Locked Laser Model

    CERN Document Server

    Moore, Richard O

    2014-01-01

    We demonstrate a trade-off between linewidth and loss-of-lock frequency in a mode-locked laser employing active feedback to control the carrier-envelope offset phase difference. In frequency metrology applications, the linewidth translates directly to uncertainty in the measured frequency, while the impact of lock loss and recovery on the measured frequency is less well understood. We reduce the dynamics to stochastic differential equations, specifically diffusion processes, and compare the linearized linewidth to the rate of lock loss determined by the mean time to exit calculated from large deviation theory.

  12. Mechanism of formation of the company optimal capital structure, different from suggested by trade off theory

    Directory of Open Access Journals (Sweden)

    Peter Brusov

    2014-12-01

    Full Text Available Under condition of proved by us insolvency of well-known classical trade off theory it becomes important to identify mechanisms for forming the optimal capital structure of a company. This paper presents one of the real such mechanisms based on the decrease of debt cost with leverage, which is determined by growth of debt volume. This mechanism is absent in perpetuity Modigliani–Miller theory, even in modified version, developed by us, and exists within more general modern theory of capital cost and capital structure by Brusov–Filatova–Orekhova, or BFO theory..

  13. The Negative Trade-off Between Risk and Incentives: Evidence from the American Whaling Industry

    OpenAIRE

    Eric Hilt

    2006-01-01

    This paper analyzes the trade-off between risk and incentives in the share contracts of the American whaling industry. Using a newly-collected panel of 5,378 individuals who sailed on whaling voyages from 1855-68, the response of sailors' compensation to an increase in risk is estimated. The risks used to identify this response resulted from the commerce-raiding naval vessels of the Confederacy during the Civil War. As the Confederate cruisers sailed primarily in the Atlantic, and therefore p...

  14. Trade-offs among ecosystem services in a typical Karst watershed, SW China.

    Science.gov (United States)

    Tian, Yichao; Wang, Shijie; Bai, Xiaoyong; Luo, Guangjie; Xu, Yan

    2016-10-01

    Nowadays, most research results on ecosystem services in Karst areas are limited to a single function of an ecosystem service. Few scholars conduct a comparative study on the mutual relationships among ecosystem services, let alone reveal the trade-off and synergic relationships in typical Karst watershed. This research aims to understand and quantitatively evaluate the relationships among ecosystem services in a typical Karst watershed, broaden the depth and width of trade-off and synergic relationships in ecosystem services and explore a set of technical processes involved in these relationships. With the Shibantang Karst watershed in China as the research site, we explore the trade-off and synergic relationships of net primary productivity (NPP), water yield, and sediment yield by coupling Soil and Water Assessment Tool (SWAT) and Carnegie-Ames-Stanford Approach (CASA), and simulating and evaluating these three ecosystem services between 2000 and 2010. Results of this study are as follows. (1) The annual average water yield decreased from 528mm in 2000 to 513mm in 2010, decreasing by 2.84%. (2) The annual average sediment yield decreased from 26.15t/ha in 2000 to 23.81t/ha in 2010, with an average annual reduction of 0.23t/ha. (3) The annual average NPP increased from 739.38gCm(-2)a(-1) in 2000 to 746.25gCm(-2)a(-1) in 2010, increasing by 6.87gCm(-2)a(-1) . (4) Water yield and sediment yield are in a synergic relationship. The increase of water yield can accumulate the soil erosion amount. NPP is in a trade-off relationship with water yield and sediment yield. The improvement of NPP is good for decreasing water yield and soil erosion amount and increasing soil conservation amount. This study provides policy makers and planners an approach to develop an integrated model, as well as design mapping and monitoring protocols for land use change and ecosystem service assessments. PMID:27265738

  15. Balancing the Trade-off Between Learning Prospects and Spillover Risks

    DEFF Research Database (Denmark)

    Perri, Alessandra; Andersson, Ulf; Nell, Phillip Christopher;

    2013-01-01

    This paper investigates local vertical linkages of foreign subsidiaries and the dual role of such linkages as conduits for learning as well as potential channels for spillovers to competitors. On the basis of data from 97 subsidiaries, we analyze the quality of such linkages under varying levels ...... find a curvilinear relationship between the extent of competitive pressure and the quality of local linkages confirming our argument of a trade-off between learning prospects and spillover risks. Furthermore, the level of subsidiary capabilities moderates this relationship....

  16. Trade-offs among ecosystem services in a typical Karst watershed, SW China.

    Science.gov (United States)

    Tian, Yichao; Wang, Shijie; Bai, Xiaoyong; Luo, Guangjie; Xu, Yan

    2016-10-01

    Nowadays, most research results on ecosystem services in Karst areas are limited to a single function of an ecosystem service. Few scholars conduct a comparative study on the mutual relationships among ecosystem services, let alone reveal the trade-off and synergic relationships in typical Karst watershed. This research aims to understand and quantitatively evaluate the relationships among ecosystem services in a typical Karst watershed, broaden the depth and width of trade-off and synergic relationships in ecosystem services and explore a set of technical processes involved in these relationships. With the Shibantang Karst watershed in China as the research site, we explore the trade-off and synergic relationships of net primary productivity (NPP), water yield, and sediment yield by coupling Soil and Water Assessment Tool (SWAT) and Carnegie-Ames-Stanford Approach (CASA), and simulating and evaluating these three ecosystem services between 2000 and 2010. Results of this study are as follows. (1) The annual average water yield decreased from 528mm in 2000 to 513mm in 2010, decreasing by 2.84%. (2) The annual average sediment yield decreased from 26.15t/ha in 2000 to 23.81t/ha in 2010, with an average annual reduction of 0.23t/ha. (3) The annual average NPP increased from 739.38gCm(-2)a(-1) in 2000 to 746.25gCm(-2)a(-1) in 2010, increasing by 6.87gCm(-2)a(-1) . (4) Water yield and sediment yield are in a synergic relationship. The increase of water yield can accumulate the soil erosion amount. NPP is in a trade-off relationship with water yield and sediment yield. The improvement of NPP is good for decreasing water yield and soil erosion amount and increasing soil conservation amount. This study provides policy makers and planners an approach to develop an integrated model, as well as design mapping and monitoring protocols for land use change and ecosystem service assessments.

  17. A study of Trade-off between Opportunistic Resource Allocation and Interference Alignment in Femtocell Scenarios

    DEFF Research Database (Denmark)

    Lertwiram, Namzilp; Popovski, Petar; Sakaguchi, Kei

    2012-01-01

    One of the main problems in wireless heterogeneous networks is interference between macro- and femto-cells. Using Orthogonal Frequency-Division Multiple Access (OFDMA) to create multiple frequency orthogonal sub-channels, this interference can be completely avoided if each sub-channel is exclusiv...... of the communication resources. In this letter we investigate the interactions and the trade-offs between these two strategies.......-channel is exclusively used by either macro- or a femto-cell. However, such an orthogonal allocation may be inefficient. We consider two alternative strategies for interference management, opportunistic resource allocation (ORA) and interference alignment (IA). Both of them utilize the fading fluctuations across...

  18. Joint venture breakup and the exploration-exploitation trade-off

    OpenAIRE

    LONG, Ngo van; Soubeyran, Antoine; Soubeyran, Raphael

    2009-01-01

    This paper explores the effect of a potential joint-venture breakup on the level of technology transfer in a set-up with exploration-exploitation trade-offs in the presence of time compression costs. We consider a joint-venture relationship between a technologically advanced multinational firm and a local firm operating in a developing economy where the ability to enforce contracts is weak, and the local firm can quit without penalties. The multinational firm has to consider the advantages an...

  19. The Trade-off between Family Size and Child Health in Rural Bangladesh

    OpenAIRE

    Christina Peters; Rees, Daniel I.; Rey Hernández-Julián

    2013-01-01

    Most of the work testing the quantity–quality model has concentrated on the trade-off between family size and educational attainment. We argue that child health is a plausible measure of child quality that has not been fully explored in the empirical literature. Using data from the Matlab Health and Socioeconomic Survey, we estimate the effect of family size on child mortality and several measures of child health. Our results suggest that even in rural Bangladesh there is little evidence of a...

  20. A note on the estimation of the equity-efficiency trade-off for QALYs.

    Science.gov (United States)

    Johannesson, M; Gerdtham, U

    1996-06-01

    In this note the veil of ignorance approach is tested as a basis for empirically determining the shape of the social welfare function for QALYs. An experiment is carried out where the participants choose between different societies that differ with respect to per capita QALYs and the distribution of QALYs. The answers are analyzed using logistic regression analysis. According to the results the respondents are willing to give up I QALY in the group with more QALYs to gain 0.45 QALYs in the group with fewer QALYs, but this trade-off is independent of the size of the difference in QALYs between the groups.

  1. Towards an Optimal Noise Versus Resolution Trade-Off in Wind Scatterometry

    Science.gov (United States)

    Williams, Brent A.

    2011-01-01

    A scatterometer is a radar that measures the normalized radar cross section sigma(sup 0) of the Earth's surface. Over the ocean this signal is related to the wind via the geophysical model function (GMF). The objective of wind scatterometry is to estimate the wind vector field from sigma(sup 0) measurements; however, there are many subtleties that complicate this problem-making it difficult to obtain a unique wind field estimate. Conventionally, wind estimation is split into two stages: a wind retrieval stage in which several ambiguous solutions are obtained, and an ambiguity removal stage in which ambiguities are chosen to produce an appropriate wind vector field estimate. The most common approach to wind field estimation is to grid the scatterometer swath into wind vector cells and estimate wind vector ambiguities independently for each cell. Then, field wise structure is imposed on the solution by an ambiguity selection routine. Although this approach is simple and practical, it neglects field wise structure in the retrieval step and does not account for the spatial correlation imposed by the sampling. This makes it difficult to develop a theoretically appropriate noise versus resolution trade-off using pointwise retrieval. Fieldwise structure may be imposed in the retrieval step using a model-based approach. However, this approach is generally only practical if a low order wind field model is applied, which may discard more information than is desired. Furthermore, model-based approaches do not account for the structure imposed by the sampling. A more general fieldwise approach is to estimate all the wind vectors for all the WVCs simultaneously from all the measurements. This approach can account for structure of the wind field as well as structure imposed by the sampling in the wind retrieval step. Williams and Long in 2010 developed a fieldwise retrieval method based on maximum a posteriori estimation (MAP). This MAP approach can be extended to perform a

  2. Nuclear energy in Europe: uranium flow modeling and fuel cycle scenario trade-offs from a sustainability perspective.

    Science.gov (United States)

    Tendall, Danielle M; Binder, Claudia R

    2011-03-15

    The European nuclear fuel cycle (covering the EU-27, Switzerland and Ukraine) was modeled using material flow analysis (MFA).The analysis was based on publicly available data from nuclear energy agencies and industries, national trade offices, and nongovernmental organizations. Military uranium was not considered due to lack of accessible data. Nuclear fuel cycle scenarios varying spent fuel reprocessing, depleted uranium re-enrichment, enrichment assays, and use of fast neutron reactors, were established. They were then assessed according to environmental, economic and social criteria such as resource depletion, waste production, chemical and radiation emissions, costs, and proliferation risks. The most preferable scenario in the short term is a combination of reduced tails assay and enrichment grade, allowing a 17.9% reduction of uranium demand without significantly increasing environmental, economic, or social risks. In the long term, fast reactors could theoretically achieve a 99.4% decrease in uranium demand and nuclear waste production. However, this involves important costs and proliferation risks. Increasing material efficiency is not systematically correlated with the reduction of other risks. This suggests that an overall optimization of the nuclear fuel cycle is difficult to obtain. Therefore, criteria must be weighted according to stakeholder interests in order to determine the most sustainable solution. This paper models the flows of uranium and associated materials in Europe, and provides a decision support tool for identifying the trade-offs of the alternative nuclear fuel cycles considered.

  3. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy.

    Science.gov (United States)

    Dang, B; Zhang, X; Chen, Y Z; Chen, C X; Wang, H T; Liu, F

    2016-01-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy. PMID:27502444

  4. Breaking through the strength-ductility trade-off dilemma in an Al-Si-based casting alloy

    Science.gov (United States)

    Dang, B.; Zhang, X.; Chen, Y. Z.; Chen, C. X.; Wang, H. T.; Liu, F.

    2016-08-01

    Al-Si-based casting alloys have a great potential in various industrial applications. Common strengthening strategies on these alloys are accompanied inevitably by sacrifice of ductility, known as strength-ductility trade-off dilemma. Here, we report a simple route by combining rapid solidification (RS) with a post-solidification heat treatment (PHT), i.e. a RS + PHT route, to break through this dilemma using a commercial Al-Si-based casting alloy (A356 alloy) as an example. It is shown that yield strength and elongation to failure of the RS + PHT processed alloy are elevated simultaneously by increasing the cooling rate upon RS, which are not influenced by subsequent T6 heat treatment. Breaking through the dilemma is attributed to the hierarchical microstructure formed by the RS + PHT route, i.e. highly dispersed nanoscale Si particles in Al dendrites and nanoscale Al particles decorated in eutectic Si. Simplicity of the RS + PHT route makes it being suitable for industrial scaling production. The strategy of engineering microstructures offers a general pathway in tailoring mechanical properties of other Al-Si-based alloys. Moreover, the remarkably enhanced ductility of A356 alloy not only permits strengthening further the material by work hardening but also enables possibly conventional solid-state forming of the material, thus extending the applications of such an alloy.

  5. Trade-offs between grounded and abstract representations: evidence from algebra problem solving.

    Science.gov (United States)

    Koedinger, Kenneth R; Alibali, Martha W; Nathan, Mitchell J

    2008-03-01

    This article explores the complementary strengths and weaknesses of grounded and abstract representations in the domain of early algebra. Abstract representations, such as algebraic symbols, are concise and easy to manipulate but are distanced from any physical referents. Grounded representations, such as verbal descriptions of situations, are more concrete and familiar, and they are more similar to physical objects and everyday experience. The complementary computational characteristics of grounded and abstract representations lead to trade-offs in problem-solving performance. In prior research with high school students solving relatively simple problems, Koedinger and Nathan (2004) demonstrated performance benefits of grounded representations over abstract representations-students were better at solving simple story problems than the analogous equations. This article extends this prior work to examine both simple and more complex problems in two samples of college students. On complex problems with two references to the unknown, a "symbolic advantage" emerged, such that students were better at solving equations than analogous story problems. Furthermore, the previously observed "verbal advantage" on simple problems was replicated. We thus provide empirical support for a trade-off between grounded, verbal representations, which show advantages on simpler problems, and abstract, symbolic representations, which show advantages on more complex problems.

  6. Prefrontal connections express individual differences in intrinsic resistance to trading off honesty values against economic benefits

    Science.gov (United States)

    Dogan, Azade; Morishima, Yosuke; Heise, Felix; Tanner, Carmen; Gibson, Rajna; Wagner, Alexander F.; Tobler, Philippe N.

    2016-01-01

    Individuals differ profoundly when they decide whether to tell the truth or to be dishonest, particularly in situations where moral motives clash with economic motives, i.e., when truthfulness comes at a monetary cost. These differences should be expressed in the decision network, particularly in prefrontal cortex. However, the interactions between the core players of the decision network during honesty-related decisions involving trade-offs with economic costs remain poorly understood. To investigate brain connectivity patterns associated with individual differences in responding to economic costs of truthfulness, we used functional magnetic resonance imaging and measured brain activations, while participants made decisions concerning honesty. We found that in participants who valued honesty highly, dorsolateral and dorsomedial parts of prefrontal cortex were more tightly coupled with the inferior frontal cortex when economic costs were high compared to when they were low. Finer-grained analysis revealed that information flow from the inferior frontal cortex to the dorsolateral prefrontal cortex and bidirectional information flow between the inferior frontal cortex and dorsomedial prefrontal cortex was associated with a reduced tendency to trade off honesty for economic benefits. Our findings provide a novel account of the neural circuitry that underlies honest decisions in the face of economic temptations. PMID:27646044

  7. West Nile virus experimental evolution in vivo and the trade-off hypothesis.

    Directory of Open Access Journals (Sweden)

    Eleanor R Deardorff

    2011-11-01

    Full Text Available In nature, arthropod-borne viruses (arboviruses perpetuate through alternating replication in vertebrate and invertebrate hosts. The trade-off hypothesis proposes that these viruses maintain adequate replicative fitness in two disparate hosts in exchange for superior fitness in one host. Releasing the virus from the constraints of a two-host cycle should thus facilitate adaptation to a single host. This theory has been addressed in a variety of systems, but remains poorly understood. We sought to determine the fitness implications of alternating host replication for West Nile virus (WNV using an in vivo model system. Previously, WNV was serially or alternately passed 20 times in vivo in chicks or mosquitoes and resulting viruses were characterized genetically. In this study, these test viruses were competed in vivo in fitness assays against an unpassed marked reference virus. Fitness was assayed in chicks and in two important WNV vectors, Culex pipiens and Culex quinquefasciatus. Chick-specialized virus displayed clear fitness gains in chicks and in Cx. pipiens but not in Cx. quinquefasciatus. Cx. pipiens-specialized virus experienced reduced fitness in chicks and little change in either mosquito species. These data suggest that when fitness is measured in birds the trade-off hypothesis is supported; but in mosquitoes it is not. Overall, these results suggest that WNV evolution is driven by alternate cycles of genetic expansion in mosquitoes, where purifying selection is weak and genetic diversity generated, and restriction in birds, where purifying selection is strong.

  8. Prefrontal connections express individual differences in intrinsic resistance to trading off honesty values against economic benefits.

    Science.gov (United States)

    Dogan, Azade; Morishima, Yosuke; Heise, Felix; Tanner, Carmen; Gibson, Rajna; Wagner, Alexander F; Tobler, Philippe N

    2016-01-01

    Individuals differ profoundly when they decide whether to tell the truth or to be dishonest, particularly in situations where moral motives clash with economic motives, i.e., when truthfulness comes at a monetary cost. These differences should be expressed in the decision network, particularly in prefrontal cortex. However, the interactions between the core players of the decision network during honesty-related decisions involving trade-offs with economic costs remain poorly understood. To investigate brain connectivity patterns associated with individual differences in responding to economic costs of truthfulness, we used functional magnetic resonance imaging and measured brain activations, while participants made decisions concerning honesty. We found that in participants who valued honesty highly, dorsolateral and dorsomedial parts of prefrontal cortex were more tightly coupled with the inferior frontal cortex when economic costs were high compared to when they were low. Finer-grained analysis revealed that information flow from the inferior frontal cortex to the dorsolateral prefrontal cortex and bidirectional information flow between the inferior frontal cortex and dorsomedial prefrontal cortex was associated with a reduced tendency to trade off honesty for economic benefits. Our findings provide a novel account of the neural circuitry that underlies honest decisions in the face of economic temptations. PMID:27646044

  9. Trading-off tolerable risk with climate change adaptation costs in water supply systems

    Science.gov (United States)

    Borgomeo, Edoardo; Mortazavi-Naeini, Mohammad; Hall, Jim W.; O'Sullivan, Michael J.; Watson, Tim

    2016-02-01

    Choosing secure water resource management plans inevitably requires trade-offs between risks (for a variety of stakeholders), costs, and other impacts. We have previously argued that water resources planning should focus upon metrics of risk of water restrictions, accompanied by extensive simulation and scenario-based exploration of uncertainty. However, the results of optimization subject to risk constraints can be sensitive to the specification of tolerable risk, which may not be precisely or consistently defined by different stakeholders. In this paper, we recast the water resources planning problem as a multiobjective optimization problem to identify least cost schemes that satisfy a set of criteria for tolerable risk, where tolerable risk is defined in terms of the frequency of water use restrictions of different levels of severity. Our proposed method links a very large ensemble of climate model projections to a water resource system model and a multiobjective optimization algorithm to identify a Pareto optimal set of water resource management plans across a 25 years planning period. In a case study application to the London water supply system, we identify water resources management plans that, for a given financial cost, maximize performance with respect to one or more probabilistic criteria. This illustrates trade-offs between financial costs of plans and risk, and between risk criteria for four different severities of water use restrictions. Graphical representation of alternative sequences of investments in the Pareto set helps to identify water management options for which there is a robust case for including them in the plan.

  10. Remarks on manipulator classification and reversibility - deflection - backlash - inertia - balance and friction trade off

    International Nuclear Information System (INIS)

    In a previous work the author proposed a time efficiency quotient based on time to perform a task for a man controlling a manipulator (RO MAN SY 73). This quotient is also a global evaluation of a man-manipulator system, and can be extended to teaching programmed manipulators. Classification based on this quotient emphasizes the importance of force feed-back to the operator, and enables to project the same concept to computer control. This paper concentrates on characteristics reflecting directly to the mechanics of the arm, to the actuators and to the control. They need delicate trade off: reversibility is key to force feed-back, deflection reflects on arm dynamics (oscillation) and precision, backlash allows lower friction but limits servo performances, inertia is high when limited deflection is required, friction is limiting the man in the loop performances, force transducers can compensate irreversibility and/or friction but lead to control sophistication. These trade offs are developed, and some proposed constants are given for force feed-back manipulators

  11. A trade-off solution between model resolution and covariance in surface-wave inversion

    Science.gov (United States)

    Xia, J.; Xu, Y.; Miller, R.D.; Zeng, C.

    2010-01-01

    Regularization is necessary for inversion of ill-posed geophysical problems. Appraisal of inverse models is essential for meaningful interpretation of these models. Because uncertainties are associated with regularization parameters, extra conditions are usually required to determine proper parameters for assessing inverse models. Commonly used techniques for assessment of a geophysical inverse model derived (generally iteratively) from a linear system are based on calculating the model resolution and the model covariance matrices. Because the model resolution and the model covariance matrices of the regularized solutions are controlled by the regularization parameter, direct assessment of inverse models using only the covariance matrix may provide incorrect results. To assess an inverted model, we use the concept of a trade-off between model resolution and covariance to find a proper regularization parameter with singular values calculated in the last iteration. We plot the singular values from large to small to form a singular value plot. A proper regularization parameter is normally the first singular value that approaches zero in the plot. With this regularization parameter, we obtain a trade-off solution between model resolution and model covariance in the vicinity of a regularized solution. The unit covariance matrix can then be used to calculate error bars of the inverse model at a resolution level determined by the regularization parameter. We demonstrate this approach with both synthetic and real surface-wave data. ?? 2010 Birkh??user / Springer Basel AG.

  12. TRADE-OFF VERSUS PECKING ORDER THEORY IN LISTED COMPANIES AROUND THE WORLD

    Directory of Open Access Journals (Sweden)

    SORANA VĂTAVU

    2012-01-01

    Full Text Available This paper provides an insight into the literature on capital structure and its determinants. The capital structure refers to the specific combination of debt and equity and their use in financing the corporate operations. Considering there are various determinants of corporate financing patters, many theories have been developed over time. From Modigliani and Miller theory, which was the first to examine the impact of capital structure on firm value, the trade-off theory and the pecking order theory are probably the most influential theories of corporate finance. The paper reveals the main financial indicators that have a significant impact on the capital structure of companies operating in both developed and under-developed financial markets. According to the particular preference for a capital structure theory, researchers showed that asset tangibility, profitability and tax shield are significant in the trade-off theory while in the pecking-order theory, the most influential factors are long-term profitability and investment opportunities. Regardless the presumed theory, most studies found firm size as essential to financing decisions.

  13. Energy efficiency trade-offs drive nucleotide usage in transcribed regions

    Science.gov (United States)

    Chen, Wei-Hua; Lu, Guanting; Bork, Peer; Hu, Songnian; Lercher, Martin J.

    2016-01-01

    Efficient nutrient usage is a trait under universal selection. A substantial part of cellular resources is spent on making nucleotides. We thus expect preferential use of cheaper nucleotides especially in transcribed sequences, which are often amplified thousand-fold compared with genomic sequences. To test this hypothesis, we derive a mutation-selection-drift equilibrium model for nucleotide skews (strand-specific usage of ‘A' versus ‘T' and ‘G' versus ‘C'), which explains nucleotide skews across 1,550 prokaryotic genomes as a consequence of selection on efficient resource usage. Transcription-related selection generally favours the cheaper nucleotides ‘U' and ‘C' at synonymous sites. However, the information encoded in mRNA is further amplified through translation. Due to unexpected trade-offs in the codon table, cheaper nucleotides encode on average energetically more expensive amino acids. These trade-offs apply to both strand-specific nucleotide usage and GC content, causing a universal bias towards the more expensive nucleotides ‘A' and ‘G' at non-synonymous coding sites. PMID:27098217

  14. Trade-offs in experimental designs for estimating post-release mortality in containment studies

    Science.gov (United States)

    Rogers, Mark W.; Barbour, Andrew B; Wilson, Kyle L

    2014-01-01

    Estimates of post-release mortality (PRM) facilitate accounting for unintended deaths from fishery activities and contribute to development of fishery regulations and harvest quotas. The most popular method for estimating PRM employs containers for comparing control and treatment fish, yet guidance for experimental design of PRM studies with containers is lacking. We used simulations to evaluate trade-offs in the number of containers (replicates) employed versus the number of fish-per container when estimating tagging mortality. We also investigated effects of control fish survival and how among container variation in survival affects the ability to detect additive mortality. Simulations revealed that high experimental effort was required when: (1) additive treatment mortality was small, (2) control fish mortality was non-negligible, and (3) among container variability in control fish mortality exceeded 10% of the mean. We provided programming code to allow investigators to compare alternative designs for their individual scenarios and expose trade-offs among experimental design options. Results from our simulations and simulation code will help investigators develop efficient PRM experimental designs for precise mortality assessment.

  15. Costs and trade-offs of grazer-induced defenses in Scenedesmus under deficient resource

    Science.gov (United States)

    Zhu, Xuexia; Wang, Jun; Chen, Qinwen; Chen, Ge; Huang, Yuan; Yang, Zhou

    2016-01-01

    The green alga Scenedesmus obliquus can form inducible defensive morphs under grazing threat. Costs and trade-offs of inducible defense are expected to accompany the benefits of defensive morphs, but are hard to detect under nutrient-sufficient experimental conditions. To test the existence of costs associated with inducible defense, we cultured S. obliquus along resource availability gradients in the presence or absence of infochemical cues from Daphnia, and measured the strength of defensive colony formation and fitness characters. Under the lowest phosphorous concentration, the expression of inducible defensive colony resulted in decreased growth rate, which provides direct evidence for physiological costs. Along the gradient reduction of phosphorous concentration or light intensity, inducible defense in S. obliquus showed a decreasing trend. However, the photosynthetic efficiency of S. obliquus was barely affected by its defense responses, suggesting that the negative correlations between resource availability and colony formation of this alga may be due to resource-based trade-offs in the allocation of limited resources. Thus, our results indicated that expression of inducible defense of S. obliquus was impaired under insufficient phosphorus or light. Furthermore, under severe phosphate deficiency, obvious physiological costs of inducible defense could be detected even though defensive colony formation also decreased significantly. PMID:26932369

  16. Parents face quantity–quality trade-offs between reproduction and investment in offspring in Iceland

    Science.gov (United States)

    Lynch, Robert Francis

    2016-01-01

    How to optimally allocate time, energy and investment in an effort to maximize one's reproductive success is a fundamental problem faced by all organisms. This effort is complicated when the production of each additional offspring dilutes the total resources available for parental investment. Although a quantity–quality trade-off between producing and investing in offspring has long been assumed in evolutionary biology, testing it directly in humans is difficult, partly owing to the long generation time of our species. Using data from an Icelandic genealogy (Íslendingabók) over two centuries, I address this issue and analyse the quantity–quality trade-off in humans. I demonstrate that the primary impact of parents on the fitness of their children is the result of resources and or investment, but not genes. This effect changes significantly across time, in response to environmental conditions. Overall, increasing reproduction has negative fitness consequences on offspring, such that each additional sibling reduces an individual's average lifespan and lifetime reproductive success. This analysis provides insights into the evolutionary conflict between producing and investing in children while also shedding light on some of the causes of the demographic transition. PMID:27293787

  17. An alternative test of the trade-off theory of capital structure

    Directory of Open Access Journals (Sweden)

    Giorgio Canarella

    2014-12-01

    Full Text Available The purpose of this paper is to investigate the stochastic behavior of corporate debt ratios utilizing a balanced panel of 2,556 publicly traded U.S. firms during the period 1997-2010. We partition the panel into ten economic sectors and perform panel unit root tests on each sector employing book value and market value measures of debt ratio. First-generation panel unit root tests provide consistent evidence that debt ratios are mean reverting, which supports the trade-off theory. However, these tests rely on the assumption that the debt ratios are cross-sectionally independent, but tests of cross-sectional independence fail to uphold this assumption. Thus, utilizing a second-generation panel unit root test that controls for cross-sectional dependence, we uncover evidence showing that debt ratios are not mean reverting, which contradicts the trade-off hypothesis. We find that the recent macroeconomic developments triggered by the financial crisis and the Great Recession have considerable explanatory power over the dynamics of the debt ratios. In fact, when we exclude the years of the recent global financial crisis, the unit root hypothesis is rejected in one half of the sectors. We interpret these results as indicative that the recent global events may have produced in these sectors a structural change in the underlying data generation process (DGP. Overall, then, we find mixed evidence on the stationarity of debt ratios.

  18. Trade-off coding for universal qudit cloners motivated by the Unruh effect

    CERN Document Server

    Jochym-O'Connor, Tomas; Wilde, Mark M

    2011-01-01

    A "triple trade-off" capacity region of a noisy quantum channel provides a more complete description of its capabilities than does a single capacity formula. However, few full descriptions of a channel's ability have been given due to the difficult nature of the calculation of such regions---it may demand an optimization of information-theoretic quantities over an infinite number of channel uses. This work analyzes the d-dimensional Unruh channel, a noisy quantum channel which emerges in relativistic quantum information theory. We show that this channel belongs to the class of quantum channels whose capacity region requires an optimization over a single channel use, and as such is tractable. We determine two triple-trade off regions, the quantum dynamic capacity region and the private dynamic capacity region, of the d-dimensional Unruh channel. Our results show that the set of achievable rate triples using this coding strategy is larger than the set achieved using a time-sharing strategy. Furthermore, we prov...

  19. The Trade-Off between Female Fertility and Longevity during the Epidemiological Transition in the Netherlands.

    Directory of Open Access Journals (Sweden)

    Ralf Kaptijn

    Full Text Available Several hypotheses have been put forward to explain the relationship between women's fertility and their post-reproductive longevity. In this study, we focus on the disposable soma theory, which posits that a negative relationship between women's fertility and longevity can be understood as an evolutionary trade-off between reproduction and survival. We examine the relationship between fertility and longevity during the epidemiological transition in the Netherlands. This period of rapid decline in mortality from infectious diseases offers a good opportunity to study the relationship between fertility and longevity, using registry data from 6,359 women born in The Netherlands between 1850 and 1910. We hypothesize that an initially negative relationship between women's fertility and their longevity gradually turns less negative during the epidemiological transition, because of decreasing costs of higher parities. An initially inversed U-shaped association between fertility and longevity changes to zero during the epidemiological transition. This does suggest a diminishing environmental pressure on fertility. However, we find no evidence of an initial linear trade-off between fertility and post-reproductive survival.

  20. The Trade-Off between Female Fertility and Longevity during the Epidemiological Transition in the Netherlands.

    Science.gov (United States)

    Kaptijn, Ralf; Thomese, Fleur; Liefbroer, Aart C; Van Poppel, Frans; Van Bodegom, David; Westendorp, Rudi G J

    2015-01-01

    Several hypotheses have been put forward to explain the relationship between women's fertility and their post-reproductive longevity. In this study, we focus on the disposable soma theory, which posits that a negative relationship between women's fertility and longevity can be understood as an evolutionary trade-off between reproduction and survival. We examine the relationship between fertility and longevity during the epidemiological transition in the Netherlands. This period of rapid decline in mortality from infectious diseases offers a good opportunity to study the relationship between fertility and longevity, using registry data from 6,359 women born in The Netherlands between 1850 and 1910. We hypothesize that an initially negative relationship between women's fertility and their longevity gradually turns less negative during the epidemiological transition, because of decreasing costs of higher parities. An initially inversed U-shaped association between fertility and longevity changes to zero during the epidemiological transition. This does suggest a diminishing environmental pressure on fertility. However, we find no evidence of an initial linear trade-off between fertility and post-reproductive survival. PMID:26680211

  1. Attention induced neural response trade-off in retinotopic cortex under load.

    Science.gov (United States)

    Torralbo, Ana; Kelley, Todd A; Rees, Geraint; Lavie, Nilli

    2016-01-01

    The effects of perceptual load on visual cortex response to distractors are well established and various phenomena of 'inattentional blindness' associated with elimination of visual cortex response to unattended distractors, have been documented in tasks of high load. Here we tested an account for these effects in terms of a load-induced trade-off between target and distractor processing in retinotopic visual cortex. Participants were scanned using fMRI while performing a visual-search task and ignoring distractor checkerboards in the periphery. Retinotopic responses to target and distractors were assessed as a function of search load (comparing search set-sizes two, three and five). We found that increased load not only increased activity in frontoparietal network, but also had opposite effects on retinotopic responses to target and distractors. Target-related signals in areas V2-V3 linearly increased, while distractor response linearly decreased, with increased load. Critically, the slopes were equivalent for both load functions, thus demonstrating resource trade-off. Load effects were also found in displays with the same item number in the distractor hemisphere across different set sizes, thus ruling out local intrahemispheric interactions as the cause. Our findings provide new evidence for load theory proposals of attention resource sharing between target and distractor leading to inattentional blindness. PMID:27625311

  2. Resolving the Connectivity-Throughput Trade-Off in Random Networks

    CERN Document Server

    Tanbourgi, Ralph; Jondral, Friedrich K

    2010-01-01

    The discrepancy between the upper bound on throughput in wireless networks and the throughput scaling in random networks which is also known as the connectivity-throughput trade-off is analyzed. In a random network with $\\lambda$ nodes per unit area, throughput is found to scale by a factor of $\\sqrt{\\log{\\lambda}}$ worse compared to the upper bound which is due to the uncertainty in the nodes' location. In the present model, nodes are assumed to know their geographical location and to employ power control, which we understand as an additional degree of freedom to improve network performance. The expected throughput-progress and the expected packet delay normalized to the one-hop progress are chosen as performance metrics. These metrics are investigated for a nearest neighbor forwarding strategy, which benefits from power control by reducing transmission power and, hence spatial contention. It is shown that the connectivity-throughput trade-off can be resolved if nodes employ a nearest neighbor forwarding str...

  3. Discovery-dominance trade-off among widespread invasive ant species.

    Science.gov (United States)

    Bertelsmeier, Cleo; Avril, Amaury; Blight, Olivier; Jourdan, Hervé; Courchamp, Franck

    2015-07-01

    Ants are among the most problematic invasive species. They displace numerous native species, alter ecosystem processes, and can have negative impacts on agriculture and human health. In part, their success might stem from a departure from the discovery-dominance trade-off that can promote co-existence in native ant communities, that is, invasive ants are thought to be at the same time behaviorally dominant and faster discoverers of resources, compared to native species. However, it has not yet been tested whether similar asymmetries in behavioral dominance, exploration, and recruitment abilities also exist among invasive species. Here, we establish a dominance hierarchy among four of the most problematic invasive ants (Linepithema humile, Lasius neglectus, Wasmannia auropunctata, Pheidole megacephala) that may be able to arrive and establish in the same areas in the future. To assess behavioral dominance, we used confrontation experiments, testing the aggressiveness in individual and group interactions between all species pairs. In addition, to compare discovery efficiency, we tested the species' capacity to locate a food resource in a maze, and the capacity to recruit nestmates to exploit a food resource. The four species differed greatly in their capacity to discover resources and to recruit nestmates and to dominate the other species. Our results are consistent with a discovery-dominance trade-off. The species that showed the highest level of interspecific aggressiveness and dominance during dyadic interactions. PMID:26257879

  4. A Trade-off between Propagation Length and Light Confinement in Cylindrical Metal-Dielectric Waveguides

    Institute of Scientific and Technical Information of China (English)

    SUN Bao-Qing; GU Ying; HU Xiao-Yong; GONG Qi-Huang

    2011-01-01

    @@ We theoretically investigate the hybrid plasmonic modes of cylindrical nanocables with gold nanocore and two dielectric nanolayers(SiO2 and BN).By solving a complete set of Maxwell's equations,the propagation constants and effective radii depending on geometrical parameters are numerically calculated.By declining a trade-off between propagation length and light confinement,high quality hybrid modes which can travel a long range of 120-200λ with a subwavelength effective radius are obtained at the optical wavelength.These modes in one-dimensional cylindrical waveguides should have potential applications in nanoscale optical device designs.%We theoretically investigate the hybrid plasmonic modes of cylindrical nanocables with gold nanocore and two dielectric nanolayers (Si02 and BN).By solving a complete set of Maxwell's equations, the propagation constants and effective radii depending on geometrical parameters are numerically calculated.By declining a trade-off between propagation length and light confinement, high quality hybrid modes which can travel a long range of 120-200λ with a subwavelength effective radius are obtained at the optical wavelength.These modes in one-dimensional cylindrical waveguides should have potential applications in nanoscale optical device designs.

  5. Robust Proactive Project Scheduling Model for the Stochastic Discrete Time/Cost Trade-Off Problem

    Directory of Open Access Journals (Sweden)

    Hongbo Li

    2015-01-01

    Full Text Available We study the project budget version of the stochastic discrete time/cost trade-off problem (SDTCTP-B from the viewpoint of the robustness in the scheduling. Given the project budget and a set of activity execution modes, each with uncertain activity time and cost, the objective of the SDTCTP-B is to minimize the expected project makespan by determining each activity’s mode and starting time. By modeling the activity time and cost using interval numbers, we propose a proactive project scheduling model for the SDTCTP-B based on robust optimization theory. Our model can generate robust baseline schedules that enable a freely adjustable level of robustness. We convert our model into its robust counterpart using a form of the mixed-integer programming model. Extensive experiments are performed on a large number of randomly generated networks to validate our model. Moreover, simulation is used to investigate the trade-off between the advantages and the disadvantages of our robust proactive project scheduling model.

  6. The adaptive dynamics of Lotka-Volterra systems with trade-offs.

    Science.gov (United States)

    Bowers, Roger G; White, Andrew

    2002-02-01

    We analyse the adaptive dynamics of a generalised type of Lotka-Volterra model subject to an explicit trade-off between two parameters. A simple expression for the fitness of a mutant strategy in an environment determined by the established, resident strategy is obtained leading to general results for the position of the evolutionary singular strategy and the associated second-order partial derivatives of the mutant fitness with respect to the mutant and resident strategies. Combinations of these results can be used to determine the evolutionary behaviour of the system. The theory is motivated by an example of prey evolution in a predator-prey system in which results show that only (non-EUS) evolutionary repellor dynamics, where evolution is directed away from a singular strategy, or dynamics where the singular strategy is an evolutionary attractor, are possible. Moreover, the general theory can be used to show that these results are the only possibility for all Lotka-Volterra systems in which aside from the trade-offs all parameters are independent and in which the interaction terms are of quadratic order or less. The applicability of the theory is highlighted by examining the evolution of an intermediate predator in a tri-trophic model.

  7. Trade-offs between the metabolic rate and population density of plants.

    Directory of Open Access Journals (Sweden)

    Jian-Ming Deng

    Full Text Available The energetic equivalence rule, which is based on a combination of metabolic theory and the self-thinning rule, is one of the fundamental laws of nature. However, there is a progressively increasing body of evidence that scaling relationships of metabolic rate vs. body mass and population density vs. body mass are variable and deviate from their respective theoretical values of 3/4 and -3/4 or -2/3. These findings questioned the previous hypotheses of energetic equivalence rule in plants. Here we examined the allometric relationships between photosynthetic mass (M(p or leaf mass (M(L vs. body mass (beta; population density vs. body mass (delta; and leaf mass vs. population density, for desert shrubs, trees, and herbaceous plants, respectively. As expected, the allometric relationships for both photosynthetic mass (i.e. metabolic rate and population density varied with the environmental conditions. However, the ratio between the two exponents was -1 (i.e. beta/delta = -1 and followed the trade-off principle when local resources were limited. Our results demonstrate for the first time that the energetic equivalence rule of plants is based on trade-offs between the variable metabolic rate and population density rather than their constant allometric exponents.

  8. Intermodal Freight Transport on the Right Track? Environmental and economic performances and their trade-off

    International Nuclear Information System (INIS)

    This dissertation aims to evaluate environmental and economic performances of an intermodal freight transport system and to estimate the trade-off between CO2 emissions, which is presented as an indicator of environmental performance, and freight costs, which indicate the economic performance of the intermodal freight system. The truck-only system is always regarded as the counterpart of the intermodal freight system in this dissertation. To examine the environmental performance of the intermodal freight system, CO2 emissions generated from all the processes in the intermodal chain, such as pre-haulage and post-haulage, long distance haulage, and transshipment, are estimated considering different sources that generate electricity and transmission loss of electricity (Chapters 3 and 4). To examine the economic performance of the system, two approaches are considered: (1) finding the intermodal breakeven distance for which the intermodal system is more competitive than the truck-only system (Chapter 5); (2) examining the economies of scale in the intermodal network and finding the route/system choice that minimizes the total freight transportation costs (Chapter 6). Finally, this dissertation attempts to find the trade-off between CO2 emissions (representing the environmental performance) and freight transportation cost (representing the economic performance) (Chapter 7)

  9. Trade-offs between soil hydrology and plant disease effects after biochar amendment in sandy soil

    Science.gov (United States)

    Verheijen, Frank; Silva, Flavio; Amaro, Antonio; Pinto, Gloria; Mesquita, Raquel; Jesus, Claudia; Alves, Artur; Keizer, Jacob

    2015-04-01

    Biochar can affect multiple soil-based ecosystem services to varying extents, leading to trade-offs. Improvements in plant-available water have predominantly been found at high biochar application rates in sandy soils. Reductions in plant diseases after biochar application have been found in various horticultural plants, and trees such as maple and oak, mostly at relatively low biochar application rates. Serious damage to Eucalyptus globulus has been reported since 1999 when frequent and severe defoliation of young trees was observed, and eucalypts are the major tree species in commercial forestry plantations of Portugal, forming an important economic activity. Here we investigated simultaneous effects on plant available water and on disease suppression of eucalypt, in a completely randomised full factorial greenhouse pot experiment, using a range of woody feedstock biochar concentrations in sandy soil. Treatments included plant inoculation with the fungus Neofusicoccum kwambonambiense and cycles of acute drought stress. Preliminary results showed delayed wilting for plants treated with 3-6% biochar, but also increased stem lesion length. These results suggest a trade-off between effects on water availability and disease for Eucalyptus globulus plants in the selected sandy soil amended with this specific biochar, at the selected application rates.

  10. Trade-off between mating opportunities and parental care: brood desertion by female Kentish plovers.

    Science.gov (United States)

    Székely, T; Cuthill, I C

    2000-10-22

    Why do some parents care for their young whereas others divorce from their mate and abandon their offspring? This decision is governed by the trade-off between the value of the current breeding event and future breeding prospects. In the precocial Kentish plover Charadrius alexandrinus females frequently, but not always, abandon their broods to be cared for by their mate, and seek new breeding partners within the same season. We have shown previously that females' remating opportunities decline with date in the season, so brood desertion should be particularly favourable for early breeding females. However, the benefits are tempered by the fact that single-parent families have lower survival expectancies than those where the female remains to help the male care for the young. We therefore tested the prediction that increasing the value of the current brood (by brood-size manipulation) should increase the duration of female care early in the season, but that in late breeders, with reduced remating opportunities, desertion and thus the duration of female care should be independent of current brood size. These predictions were fulfilled, indicating that seasonally modulated trade-offs between current brood value and remating opportunities can be important in the desertion decisions of species with flexible patterns of parental care. PMID:11416913

  11. Modeling the trade-off between transmissibility and contact in infectious disease dynamics.

    Science.gov (United States)

    Lin, Chiu-Ju; Deger, Kristen A; Tien, Joseph H

    2016-07-01

    Symptom severity affects disease transmission both by impacting contact rates, as well as by influencing the probability of transmission given contact. This involves a trade-off between these two factors, as increased symptom severity will tend to decrease contact rates, but increase the probability of transmission given contact (as pathogen shedding rates increase with symptom severity). This paper explores this trade-off between contact and transmission given contact, using a simple compartmental susceptible-infected-recovered type model. Under mild assumptions on how contact and transmission probability vary with symptom severity, we give sufficient, biologically intuitive criteria for when the basic reproduction number varies non-monotonically with symptom severity. Multiple critical points are possible. We give a complete characterization of the region in parameter space where multiple critical points are located in the special case where contact rate decreases exponentially with symptom severity. We consider a multi-strain version of the model with complete cross-immunity and no super-infection. In this model, we prove that the strain with highest basic reproduction number drives the other strains to extinction. This has both evolutionary and epidemiological implications, including the possibility of an intervention paradoxically resulting in increased infection prevalence. PMID:27102055

  12. Power and Performance Trade-offs for Space Time Adaptive Processing

    Energy Technology Data Exchange (ETDEWEB)

    Gawande, Nitin A.; Manzano Franco, Joseph B.; Tumeo, Antonino; Tallent, Nathan R.; Kerbyson, Darren J.; Hoisie, Adolfy

    2015-07-27

    Computational efficiency – performance relative to power or energy – is one of the most important concerns when designing RADAR processing systems. This paper analyzes power and performance trade-offs for a typical Space Time Adaptive Processing (STAP) application. We study STAP implementations for CUDA and OpenMP on two computationally efficient architectures, Intel Haswell Core I7-4770TE and NVIDIA Kayla with a GK208 GPU. We analyze the power and performance of STAP’s computationally intensive kernels across the two hardware testbeds. We also show the impact and trade-offs of GPU optimization techniques. We show that data parallelism can be exploited for efficient implementation on the Haswell CPU architecture. The GPU architecture is able to process large size data sets without increase in power requirement. The use of shared memory has a significant impact on the power requirement for the GPU. A balance between the use of shared memory and main memory access leads to an improved performance in a typical STAP application.

  13. Power-efficiency trade-off in low-dimensional thermoelectrics- An RTD study

    Science.gov (United States)

    Agarwal, Akshay; Muralidharan, Bhaskaran

    2014-03-01

    A distortion in the quantum mechanical transmission due to confinement in a low-dimensional thermoelectric often points to a better figure of merit (zT). While an enhancement in zT is a highly desirable feature for a good thermoelectric, it does not provide a complete picture of the thermoelectric operation. One such aspect not apparent with a zT-based anaylsis is the trade-off between the power generated and the efficiency resulting from such a distortion. Another aspect is the role of Coulomb charging resulting from the confinement. In this talk, we elucidate the role of charging as well as the distortion in the transmission function on the thermoelectric performance using a double barrier resonant tunneling diode (RTD) set up. Transport simulations are performed using the non-equilibrium Green's function (NEGF) formalism coupled self-consistently with the Poisson equation. Various levels of transmission distortion and charging scenarios are achieved by tailoring the physical parameter space of the RTD device. The resulting set of physical situations in the simulated RTD device will provide a detailed insight into the power-efficiency trade-off trend that should result from a generic quantum confinement scenario.

  14. Strategic trade-offs between quantity and quality in working memory.

    Science.gov (United States)

    Fougnie, Daryl; Cormiea, Sarah M; Kanabar, Anish; Alvarez, George A

    2016-08-01

    Is working memory capacity determined by an immutable limit-for example, 4 memory storage slots? The fact that performance is typically unaffected by task instructions has been taken as support for such structural models of memory. Here, we modified a standard working memory task to incentivize participants to remember more items. Participants were asked to remember a set of colors over a short retention interval. In 1 condition, participants reported a random item's color using a color wheel. In the modified task, participants responded to all items and their response was only considered correct if all responses were on the correct half of the color wheel. We looked for a trade-off between quantity and quality-participants storing more items, but less precisely, when required to report them all. This trade-off was observed when tasks were blocked and when task-type was cued after encoding, but not when task-type was cued during the response, suggesting that task differences changed how items were actively encoded and maintained. This strategic control over the contents of working memory challenges models that assume inflexible limits on memory storage. (PsycINFO Database Record PMID:26950383

  15. Unified trade-off optimization for general heat devices with nonisothermal processes

    Science.gov (United States)

    Long, Rui; Liu, Wei

    2015-04-01

    An analysis of the efficiency and coefficient of performance (COP) for general heat engines and refrigerators with nonisothermal processes is conducted under the trade-off criterion. The specific heat of the working medium has significant impacts on the optimal configurations of heat devices. For cycles with constant specific heat, the bounds of the efficiency and COP are found to be the same as those obtained through the endoreversible Carnot ones. However, they are independent of the cycle time durations. For cycles with nonconstant specific heat, whose dimensionless contact time approaches infinity, the general alternative upper and lower bounds of the efficiency and COP under the trade-off criteria have been proposed under the asymmetric limits. Furthermore, when the dimensionless contact time approaches zero, the endoreversible Carnot model is recovered. In addition, the efficiency and COP bounds of different kinds of actual heat engines and refrigerators have also been analyzed. This paper may provide practical insight for designing and operating actual heat engines and refrigerators.

  16. Energy efficiency trade-offs drive nucleotide usage in transcribed regions.

    Science.gov (United States)

    Chen, Wei-Hua; Lu, Guanting; Bork, Peer; Hu, Songnian; Lercher, Martin J

    2016-04-21

    Efficient nutrient usage is a trait under universal selection. A substantial part of cellular resources is spent on making nucleotides. We thus expect preferential use of cheaper nucleotides especially in transcribed sequences, which are often amplified thousand-fold compared with genomic sequences. To test this hypothesis, we derive a mutation-selection-drift equilibrium model for nucleotide skews (strand-specific usage of 'A' versus 'T' and 'G' versus 'C'), which explains nucleotide skews across 1,550 prokaryotic genomes as a consequence of selection on efficient resource usage. Transcription-related selection generally favours the cheaper nucleotides 'U' and 'C' at synonymous sites. However, the information encoded in mRNA is further amplified through translation. Due to unexpected trade-offs in the codon table, cheaper nucleotides encode on average energetically more expensive amino acids. These trade-offs apply to both strand-specific nucleotide usage and GC content, causing a universal bias towards the more expensive nucleotides 'A' and 'G' at non-synonymous coding sites.

  17. A test of energetic trade-offs between growth and immune function in watersnakes.

    Science.gov (United States)

    Korfel, Chelsea A; Chamberlain, Jeremy D; Gifford, Matthew E

    2015-10-01

    Energy budgets explain how organisms allocate energetic intake to accomplish essential processes. A likely life history trade-off occurs between growth and immune response in juvenile organisms, where growth is important to avoid predation or obtain larger prey and immune response is essential to survival in the presence of environmental pathogens. We examined the innate (wound healing) and adaptive (lymphoid tissue, thymus and spleen) components of immune response along with growth in two populations of the diamond-backed watersnake Nerodia rhombifer raised in a common environment. We found that neonate snakes born to females from populations characterized by different predator and prey environments did not differ in energetic intake, but snakes from the population containing large prey grew significantly faster than those from a population containing small prey. Thymus mass, when corrected for body mass, was larger in snakes from the small prey population than in snakes from the large prey population. Additionally, the snakes from the population containing small prey healed significantly faster than those from the population containing large prey. Thus, we detected a negative correlation between growth (over a 4-month period) and wound healing across populations that is suggestive of an energetic trade-off between growth and immune response. The differences observed in growth and immune response among these two populations appear to suggest different energy allocation strategies to maximize fitness in response to differing conditions experienced by snakes in the two populations. PMID:26062440

  18. No evidence for a trade-off between sperm length and male premating weaponry.

    Science.gov (United States)

    Lüpold, S; Simmons, L W; Tomkins, J L; Fitzpatrick, J L

    2015-12-01

    Male ornaments and armaments that mediate success in mate acquisition and ejaculate traits influencing competitive fertilization success are under intense sexual selection. However, relative investment in these pre- and post-copulatory traits depends on the relative importance of either selection episode and on the energetic costs and fitness gains of investing in these traits. Theoretical and empirical work has improved our understanding of how precopulatory sexual traits and investments in sperm production covary in this context. It has recently also been suggested that male weapon size may trade off with sperm length as another post-copulatory sexual trait, but the theoretical framework for this suggestion remains unclear. We evaluated the relationship between precopulatory armaments and sperm length, previously reported in ungulates, in five taxa as well as meta-analytically. Within and between taxa, we found no evidence for a negative or positive relationship between sperm length and male traits that are important in male-male contest competition. It is important to consider pre- and post-copulatory sexual selection together to understand fitness, and to study investments in different reproductive traits jointly rather than separately. A trade-off between pre- and post-copulatory sexual traits may not manifest itself in sperm length but rather in sperm number or function. Particularly in large-bodied taxa such as ungulates, sperm number is more variable interspecifically and likely to be under more intense selection than sperm length. We discuss our and the previous results in this context. PMID:26332435

  19. Sampling design trade-offs in occupancy studies with imperfect detection: examples and software

    Science.gov (United States)

    Bailey, L.L.; Hines, J.E.; Nichols, J.D.

    2007-01-01

    Researchers have used occupancy, or probability of occupancy, as a response or state variable in a variety of studies (e.g., habitat modeling), and occupancy is increasingly favored by numerous state, federal, and international agencies engaged in monitoring programs. Recent advances in estimation methods have emphasized that reliable inferences can be made from these types of studies if detection and occupancy probabilities are simultaneously estimated. The need for temporal replication at sampled sites to estimate detection probability creates a trade-off between spatial replication (number of sample sites distributed within the area of interest/inference) and temporal replication (number of repeated surveys at each site). Here, we discuss a suite of questions commonly encountered during the design phase of occupancy studies, and we describe software (program GENPRES) developed to allow investigators to easily explore design trade-offs focused on particularities of their study system and sampling limitations. We illustrate the utility of program GENPRES using an amphibian example from Greater Yellowstone National Park, USA.

  20. Performance Trade-Offs for Wavelength Striping Optical Switching Using a Novel Star Architecture

    Directory of Open Access Journals (Sweden)

    Enrique Rodriguez-Colina

    2016-01-01

    Full Text Available This work describes various performance trade-offs that arise from the use of a technique for optical switching under various network topologies. Such switching operation can be summarized as follows: (a user data are divided into fixed-length fragments, (b each fragment is assigned to a different wavelength, and (c all wavelengths are simultaneously switched to the egress links. This concept of dividing user data into several wavelengths to be simultaneously switched is called wavelength striping and its purpose is to reduce latency and increase throughput for short distance interconnects. We depart from previous work where a building block implementing this basic switching function has been built around semiconductor optical amplifiers (SOAs. In this paper, we investigate diverse trade-offs that arise from the use of this switching approach in different network topologies. One of the main issues addressed in this paper is the relation between cascadability and bit error rate (BER. In this case, our results indicate that a switch fabric can cascade up to five stages without exceeding a BER of 10−9 and without incurring in power budget problems. We also show that the performance degradation, introduced by cascading SOAs, can be compensated with a star interconnect architecture that is introduced. Other issues addressed in this paper are the effect of scalability on cost and the effect of latency on TCP performance and reliability.

  1. EuroQol Protocols for Time Trade-Off Valuation of Health Outcomes.

    Science.gov (United States)

    Oppe, Mark; Rand-Hendriksen, Kim; Shah, Koonal; Ramos-Goñi, Juan M; Luo, Nan

    2016-10-01

    The time trade-off (TTO) valuation technique is widely used to determine utility values of health outcomes to inform quality-adjusted life-year (QALY) calculations for use in economic evaluation. Protocols for implementing TTO vary in aspects such as the trade-off framework, iteration procedure and its administration model and method, training of respondents and interviewers, and quality control of data collection. The most widely studied and utilized TTO valuation protocols are the Measurement and Valuation of Health (MVH) protocol, the Paris protocol and the EuroQol Valuation Technology (EQ-VT) protocol, all developed by members of the EuroQol Group. The MVH protocol and its successor, the Paris protocol, were developed for valuation of EQ-5D-3L health states. Both protocols were designed for a trained interviewer to elicit preferences from a respondent using the conventional TTO framework with a fixed time horizon of 10 years and an iteration procedure combining bisection and titration. Developed for valuation of EQ-5D-5L health states, the EQ-VT protocol adopted a composite TTO framework and made use of computer technology to facilitate data collection. Training and monitoring of interviewers and respondents is a pivotal component of the EQ-VT protocol. Research is underway aiming to further improve the EuroQol protocols, which form an important basis for the current practice of health technology assessment in many countries.

  2. Viruses' life history: towards a mechanistic basis of a trade-off between survival and reproduction among phages.

    Directory of Open Access Journals (Sweden)

    Marianne De Paepe

    2006-07-01

    Full Text Available Life history theory accounts for variations in many traits involved in the reproduction and survival of living organisms, by determining the constraints leading to trade-offs among these different traits. The main life history traits of phages-viruses that infect bacteria-are the multiplication rate in the host, the survivorship of virions in the external environment, and their mode of transmission. By comparing life history traits of 16 phages infecting the bacteria Escherichia coli, we show that their mortality rate is constant with time and positively [corrected] correlated to their multiplication rate in the bacterial host. Even though these viruses do not age, this result is in line with the trade-off between survival and reproduction previously observed in numerous aging organisms. Furthermore, a multiple regression shows that the combined effects of two physical parameters, namely, the capsid thickness and the density of the packaged genome, account for 82% of the variation in the mortality rate. The correlations between life history traits and physical characteristics of virions may provide a mechanistic explanation of this trade-off. The fact that this trade-off is present in this very simple biological situation suggests that it might be a fundamental property of evolving entities produced under constraints. Moreover, such a positive correlation between mortality and multiplication reveals an underexplored trade-off in host-parasite interactions.

  3. Adaptive dynamics of Lotka-Volterra systems with trade-offs: the role of interspecific parameter dependence in branching.

    Science.gov (United States)

    White, Andrew; Bowers, Roger G

    2005-01-01

    We determine the adaptive dynamics of a general Lotka-Volterra system containing an intraspecific parameter dependency--in the form of an explicit functional trade-off between evolving parameters--and interspecific parameter dependencies--arising from modelling species interactions. We develop expressions for the fitness of a mutant strategy in a multi-species resident environment, the position of the singular strategy in such systems and the non-mixed second-order partial derivatives of the mutant fitness. These expressions can be used to determine the evolutionary behaviour of the system. The type of behaviour expected depends on the curvature of the trade-off function and can be interpreted in a biologically intuitive manner using the rate of acceleration/deceleration of the costs implicit in the trade-off function. We show that for evolutionary branching to occur we require that one (or both) of the traded-off parameters includes an interspecific parameter dependency and that the trade-off function has weakly accelerating costs. This could have important implications for understanding the type of mechanisms that cause speciation. The general theory is motivated by using adaptive dynamics to examine evolution in a predator-prey system. The applicability of the general theory as a tool for examining specific systems is highlighted by calculating the evolutionary behaviour in a three species (prey-predator-predator) system.

  4. Pleiotropic effects of juvenile hormone in ant queens and the escape from the reproduction-immunocompetence trade-off.

    Science.gov (United States)

    Pamminger, Tobias; Treanor, David; Hughes, William O H

    2016-01-13

    The ubiquitous trade-off between survival and costly reproduction is one of the most fundamental constraints governing life-history evolution. In numerous animals, gonadotropic hormones antagonistically suppressing immunocompetence cause this trade-off. The queens of many social insects defy the reproduction-survival trade-off, achieving both an extraordinarily long life and high reproductive output, but how they achieve this is unknown. Here we show experimentally, by integrating quantification of gene expression, physiology and behaviour, that the long-lived queens of the ant Lasius niger have escaped the reproduction-immunocompetence trade-off by decoupling the effects of a key endocrine regulator of fertility and immunocompetence in solitary insects, juvenile hormone (JH). This modification of the regulatory architecture enables queens to sustain a high reproductive output without elevated JH titres and suppressed immunocompetence, providing an escape from the reproduction-immunocompetence trade-off that may contribute to the extraordinary lifespan of many social insect queens. PMID:26763704

  5. Analog circuits using FinFETs: benefits in speed-accuracy-power trade-off and simulation of parasitic effects

    Directory of Open Access Journals (Sweden)

    M. Fulde

    2007-06-01

    Full Text Available Multi-gate FET, e.g. FinFET devices are the most promising contenders to replace bulk FETs in sub-45 nm CMOS technologies due to their improved sub threshold and short channel behavior, associated with low leakage currents. The introduction of novel gate stack materials (e.g. metal gate, high-k dielectric and modified device architectures (e.g. fully depleted, undoped fins affect the analog device properties significantly. First measurements indicate enhanced intrinsic gain (gm/gDS and promising matching behavior of FinFETs. The resulting benefits regarding the speed-accuracy-power trade-off in analog circuit design will be shown in this work. Additionally novel device specific effects will be discussed. The hysteresis effect caused by charge trapping in high-k dielectrics or self-heating due to the high thermal resistor of the BOX isolation are possible challenges for analog design in these emerging technologies. To gain an early assessment of the impact of such parasitic effects SPICE based models are derived and applied in analog building blocks.

  6. Construct validity of the interview Time Trade-Off and computer Time Trade-Off in patients with rheumatoid arthritis: A cross-sectional observational pilot study

    Directory of Open Access Journals (Sweden)

    Buitinga Laurien

    2012-06-01

    Full Text Available Abstract Background The Time Trade-Off (TTO is a widely used instrument for valuing preference-based health-related quality of life (HRQoL. The TTO reveals preferences for own current health (‘utilities’ on a scale anchored between death (0 and perfect health (1. Limited information on the external validity of the TTO is available. Aim of this pilot study was to examine the construct validity of both an interview TTO and a computer-based TTO in patients with rheumatoid arthritis (RA. Methods Thirty patients visiting the outpatient rheumatology clinic participated. Construct validity was assessed by measuring convergent and discriminative validity. Convergent validity was assessed by calculating Spearman’s correlations between the utilities obtained from the TTOs and pain, general health (rating scales, health-related quality of life (SF-36 and SF-6D and functional status (HAQ-DI. Discriminative power of both TTO measures was determined by comparing median utilities between worse and better health outcomes. Results Correlations of both TTO measures with HRQoL, general health, pain and functional status were poor (absolute values ranging from .05 to .26. Both TTOs appeared to have no discriminative value among groups of RA patients who had a worse or better health status defined by six health outcome measures. About one-third of respondents were zero-traders on each of the TTO measures. After excluding zero-traders from analysis, the correlations improved considerably. Conclusions Both the interview TTO and computer TTO showed poor construct validity in RA patients when using measures of HRQol, general health, pain and functional status as reference measures. Possibly, the validity of the TTO improves when using an anchor that is more realistic to RA patients than the anchor ‘death’.

  7. Trade-off between morphological convergence and opportunistic diet behavior in fish hybrid zone

    Directory of Open Access Journals (Sweden)

    Grey Jonathan

    2009-10-01

    Full Text Available Abstract Background The invasive Chondrostoma nasus nasus has colonized part of the distribution area of the protected endemic species Chondrostoma toxostoma toxostoma. This hybrid zone is a complex system where multiple effects such as inter-species competition, bi-directional introgression, strong environmental pressure and so on are combined. Why do sympatric Chondrostoma fish present a unidirectional change in body shape? Is this the result of inter-species interactions and/or a response to environmental effects or the result of trade-offs? Studies focusing on the understanding of a trade-off between multiple parameters are still rare. Although this has previously been done for Cichlid species flock and for Darwin finches, where mouth or beak morphology were coupled to diet and genetic identification, no similar studies have been done for a fish hybrid zone in a river. We tested the correlation between morphology (body and mouth morphology, diet (stable carbon and nitrogen isotopes and genomic combinations in different allopatric and sympatric populations for a global data set of 1330 specimens. To separate the species interaction effect from the environmental effect in sympatry, we distinguished two data sets: the first one was obtained from a highly regulated part of the river and the second was obtained from specimens coming from the less regulated part. Results The distribution of the hybrid combinations was different in the two part of the sympatric zone, whereas all the specimens presented similar overall changes in body shape and in mouth morphology. Sympatric specimens were also characterized by a larger diet behavior variance than reference populations, characteristic of an opportunistic diet. No correlation was established between the body shape (or mouth deformation and the stable isotope signature. Conclusion The Durance River is an untamed Mediterranean river despite the presence of numerous dams that split the river from

  8. Speed-difficulty trade-off in speech: Chinese versus English.

    Science.gov (United States)

    Latash, Mark L; Sun, Yao; Latash, Elizaveta M; Mikaelian, Irina L

    2011-06-01

    This study continues the investigation of the previously described speed-difficulty trade-off in picture description tasks. In particular, we tested a hypothesis that the Mandarin Chinese and American English are similar in showing logarithmic dependences between speech time and index of difficulty (ID), while they differ significantly in the amount of time needed to describe simple pictures, this difference increases for more complex pictures, and it is associated with a proportional difference in the number of syllables used. Subjects (eight Chinese speakers and eight English speakers) were tested in pairs. One subject (the Speaker) described simple pictures, while the other subject (the Performer) tried to reproduce the pictures based on the verbal description as quickly as possible with a set of objects. The Chinese speakers initiated speech production significantly faster than the English speakers. Speech time scaled linearly with ln(ID) in all subjects, but the regression coefficient was significantly higher in the English speakers as compared with the Chinese speakers. The number of errors was somewhat lower in the Chinese participants (not significantly). The Chinese pairs also showed a shorter delay between the initiation of speech and initiation of action by the Performer, shorter movement time by the Performer, and shorter overall performance time. The number of syllables scaled with ID, and the Chinese speakers used significantly smaller numbers of syllables. Speech rate was comparable between the two groups, about 3 syllables/s; it dropped for more complex pictures (higher ID). When asked to reproduce the same pictures without speaking, movement time scaled linearly with ln(ID); the Chinese performers were slower than the English performers. We conclude that natural languages show a speed-difficulty trade-off similar to Fitts' law; the trade-offs in movement and speech production are likely to originate at a cognitive level. The time advantage of the

  9. Assessing the Climate Trade-Offs of Gasoline Direct Injection Engines.

    Science.gov (United States)

    Zimmerman, Naomi; Wang, Jonathan M; Jeong, Cheol-Heon; Wallace, James S; Evans, Greg J

    2016-08-01

    Compared to port fuel injection (PFI) engine exhaust, gasoline direct injection (GDI) engine exhaust has higher emissions of black carbon (BC), a climate-warming pollutant. However, the relative increase in BC emissions and climate trade-offs of replacing PFI vehicles with more fuel efficient GDI vehicles remain uncertain. In this study, BC emissions from GDI and PFI vehicles were compiled and BC emissions scenarios were developed to evaluate the climate impact of GDI vehicles using global warming potential (GWP) and global temperature potential (GTP) metrics. From a 20 year time horizon GWP analysis, average fuel economy improvements ranging from 0.14 to 14% with GDI vehicles are required to offset BC-induced warming. For all but the lowest BC scenario, installing a gasoline particulate filter with an 80% BC removal efficiency and technology are minimal. PMID:27406325

  10. Dynamics of large femtosecond filament arrays: possibilities, limitations, and trade-offs

    CERN Document Server

    Walasik, Wiktor

    2015-01-01

    Stable propagation of large, multifilament arrays over long distances in air paves new ways for microwave-radiation manipulation. Although, the dynamics of a single or a few filaments was discussed in some of the previous studies, we show that the stability of large plasma filament arrays is significantly more complicated and is constrained by several trade-offs. Here, we analyze the stability properties of rectangular arrays as a function of four parameters: relative phase of the generating beams, number of filaments, separation between them, and initial power. We find that arrays with alternating phase of filaments are more stable than similar arrays with all beams in phase. Additionally, we show that increasing the size of an array increases its stability, and that a proper choice of the beam separation and the initial power has to be made in order to obtain a dense and regular array of filaments.

  11. Chunking as the result of an efficiency computation trade-off.

    Science.gov (United States)

    Ramkumar, Pavan; Acuna, Daniel E; Berniker, Max; Grafton, Scott T; Turner, Robert S; Kording, Konrad P

    2016-01-01

    How to move efficiently is an optimal control problem, whose computational complexity grows exponentially with the horizon of the planned trajectory. Breaking a compound movement into a series of chunks, each planned over a shorter horizon can thus reduce the overall computational complexity and associated costs while limiting the achievable efficiency. This trade-off suggests a cost-effective learning strategy: to learn new movements we should start with many short chunks (to limit the cost of computation). As practice reduces the impediments to more complex computation, the chunking structure should evolve to allow progressively more efficient movements (to maximize efficiency). Here we show that monkeys learning a reaching sequence over an extended period of time adopt this strategy by performing movements that can be described as locally optimal trajectories. Chunking can thus be understood as a cost-effective strategy for producing and learning efficient movements. PMID:27397420

  12. Study on RLS trade-off resist upgrade for production ready EUV lithography

    Science.gov (United States)

    Lee, Junghyung; Kim, Jieun; Jeong, Seunguk; Lim, Mijung; Koo, Sunyoung; Lim, Chang-Moon; Kim, Young-Sik

    2016-03-01

    Extreme Ultraviolet (EUV) is the most promising technology as substitute for multiple patterning based on ArF immersion lithography. If enough productivity can be accomplished, EUV will take main role in the chip manufacturing. Since the introduction of NXE3300, many significant results have been achieved in source power and availability, but lots of improvements are still required in various aspects for the implementation of EUV lithography on high volume manufacturing. Among them, it is especially important to attain high sensitivity resist without degrading other resolution performance. In this paper, performances of various resists were evaluated with real device patterns on NXE3300 scanner and technical progress of up-to-date EUV resists will be shown by comparing with the performance of their predecessors. Finally the prospect of overcoming the triangular trade-off between sensitivity, resolution, line edge roughness (LER) and achieving high volume manufacturing will be discussed.

  13. Scheduling and Optimization of Fault-Tolerant Embedded Systems with Transparency/Performance Trade-Offs

    DEFF Research Database (Denmark)

    Izosimov, Viacheslav; Pop, Paul; Eles, Petru;

    2012-01-01

    In this article, we propose a strategy for the synthesis of fault-tolerant schedules and for the mapping of fault-tolerant applications. Our techniques handle transparency/performance trade-offs and use the faultoccurrence information to reduce the overhead due to fault tolerance. Processes...... and messages are statically scheduled, and we use process reexecution for recovering from multiple transient faults. We propose a finegrained transparent recovery, where the property of transparency can be selectively applied to processes and messages. Transparency hides the recovery actions in a selected part...... of the application so that they do not affect the schedule of other processes and messages. While leading to longer schedules, transparent recovery has the advantage of both improved debuggability and less memory needed to store the faulttolerant schedules....

  14. Gemini multi-conjugate adaptive optics system review I: Design, trade-offs and integration

    CERN Document Server

    Rigaut, Francois; Boccas, Maxime; d'Orgeville, Céline; Vidal, Fabrice; van Dam, Marcos A; Arriagada, Gustavo; Fesquet, Vincent; Galvez, Ramon L; Gausachs, Gaston; Cavedoni, Chad; Ebbers, Angelic W; Karewicz, Stan; James, Eric; Lührs, Javier; Montes, Vanessa; Perez, Gabriel; Rambold, William N; Rojas, Roberto; Walker, Shane; Bec, Matthieu; Trancho, Gelys; Sheehan, Michael; Irarrazaval, Benjamin; Boyer, Corinne; Ellerbroek, Brent L; Flicker, Ralf; Gratadour, Damien; Garcia-Rissmann, Aurea; Daruich, Felipe

    2013-01-01

    The Gemini Multi-conjugate adaptive optics System (GeMS) at the Gemini South telescope in Cerro Pach{\\'o}n is the first sodium-based multi-Laser Guide Star (LGS) adaptive optics system. It uses five LGSs and two deformable mirrors to measure and compensate for atmospheric distortions. The GeMS project started in 1999, and saw first light in 2011. It is now in regular operation, producing images close to the diffraction limit in the near infrared, with uniform quality over a field of view of two square arcminutes. The present paper (I) is the first one in a two-paper review of GeMS. It describes the system, explains why and how it was built, discusses the design choices and trade-offs, and presents the main issues encountered during the course of the project. Finally, we briefly present the results of the system first light.

  15. Design principles and fundamental trade-offs in biomimetic light harvesting

    CERN Document Server

    Sarovar, Mohan

    2012-01-01

    Recent developments in synthetic and supramolecular chemistry have created opportunities to design organic systems with tailored nanoscale structure for various technological applications. A key application area is the capture of light energy and its conversion into electrochemical or chemical forms for photovoltaic or sensing applications. In this work we consider cylindrical assemblies of chromophores that model structures produced by several supramolecular techniques. Our study is especially guided by the versatile structures produced by virus-templated assembly. We use a multi-objective optimization framework to determine design principles and limitations in light harvesting performance for such assemblies, both in the presence and absence of disorder. We identify a fundamental trade-off in cylindrical assemblies that is encountered when attempting to maximize both efficiency of energy transfer and absorption bandwidth. We also rationalize the optimal design strategies and provide explanations for why var...

  16. Local vs. global redundancy - trade-offs between resilience against cascading failures and frequency stability

    Science.gov (United States)

    Plietzsch, A.; Schultz, P.; Heitzig, J.; Kurths, J.

    2016-05-01

    When designing or extending electricity grids, both frequency stability and resilience against cascading failures have to be considered amongst other aspects of energy security and economics such as construction costs due to total line length. Here, we compare an improved simulation model for cascading failures with state-of-the-art simulation models for short-term grid dynamics. Random ensembles of realistic power grid topologies are generated using a recent model that allows for a tuning of global vs local redundancy. The former can be measured by the algebraic connectivity of the network, whereas the latter can be measured by the networks transitivity. We show that, while frequency stability of an electricity grid benefits from a global form of redundancy, resilience against cascading failures rather requires a more local form of redundancy and further analyse the corresponding trade-off.

  17. Improved Power-Delay Trade-off in Wireless Networks Using Opportunistic Routing

    CERN Document Server

    Shin, Won-Yong; Lee, Yong H

    2009-01-01

    We study the benefits of opportunistic routing in wireless networks by examining how the power and delay scale as the number of source-destination (S-D) pairs in the network increases. The scaling behavior of conventional multi-hop transmission that does not employ opportunistic routing is also examined for comparison. Our results indicate that opportunistic routing can exhibit a better power--delay trade-off than that of conventional routing by providing up to a logarithmic boost in the scaling law. Such a gain is possible since the receivers can tolerate more interference due to the increased received signal power provided by the multi-user diversity (MUD) gain, which means having more simultaneous transmissions is possible. Computer simulations for both routing schemes are also performed, which show trends consistent with our analytical predictions.

  18. Configuration trade-offs for the Space Infrared Telescope Facility pointing control system

    Science.gov (United States)

    Pue, A. J.; Strohbehn, K.; Hunt, J. W.

    1985-01-01

    Conceptual pointing control system designs for the Space Infrared Telescope Facility (SIRTF) are examined in terms of fine guidance pointing and large-angle slewing accuracies. In particular, basic trade-offs between body pointing only and body pointing plus image motion compensation (IMC) are considered using a steady-state linear covariance analysis to compute rms pointing errors. It is shown that body pointing can provide good performance during nominal fine pointing but limits the telescope capability to rapidly slew and acquire targets. Overall, body pointing plus IMC would offer superior performance but must be judged against the difficulties posed by the attitude sensor noise and the higher cost and complexity of IMC. It is recommended that improved sensor designs be pursued while slewing performance be enhanced by a combination of an appropriate command profile and control compensation.

  19. Drivers, constraints and trade-offs associated with recultivating abandoned cropland in Russia, Ukraine and Kazakhstan

    DEFF Research Database (Denmark)

    Meyfroidt, Patrick; Schierhorn, Florian; Prishchepov, Alexander;

    2016-01-01

    and habitat for biodiversity. Less cropland abandonment and more recultivation after 2000 occurred in areas with an increasing rural population and a younger labor force, but also improved yields. Synergies were observed between cropland recultivation and intensification over the 2000s. From 47.3 million...... hectares (Mha) of cropland abandoned in 2009, we identified only 8.5 (7.1–17.4) Mha of potentially available cropland with low environmental tradeoffs and low to moderate socio-economic or accessibility constraints that were located on high-quality soils (Chernozems). These areas represented an annual...... wheat production potential of 14.3 (9.6–19.5) million tons (Mt). Conversely, 8.5 (4.2–12.4) Mha had high carbon or biodiversity trade-offs, of which 10% might be attractive for cropland expansion and thus would require protection from recultivation. Agroenvironmental, accessibility, and socio...

  20. The Trade-Off between Female Fertility and Longevity during the Epidemiological Transition in the Netherlands

    DEFF Research Database (Denmark)

    Kaptijn, Ralf; Thomese, Fleur; Liefbroer, Aart C;

    2015-01-01

    Several hypotheses have been put forward to explain the relationship between women's fertility and their post-reproductive longevity. In this study, we focus on the disposable soma theory, which posits that a negative relationship between women's fertility and longevity can be understood...... fertility and longevity, using registry data from 6,359 women born in The Netherlands between 1850 and 1910. We hypothesize that an initially negative relationship between women's fertility and their longevity gradually turns less negative during the epidemiological transition, because of decreasing costs...... of higher parities. An initially inversed U-shaped association between fertility and longevity changes to zero during the epidemiological transition. This does suggest a diminishing environmental pressure on fertility. However, we find no evidence of an initial linear trade-off between fertility and post...

  1. Hardware performance versus video quality trade-off for Gaussian mixture model based background identification systems

    Science.gov (United States)

    Genovese, Mariangela; Napoli, Ettore; Petra, Nicola

    2014-04-01

    Background identification is a fundamental task in many video processing systems. The Gaussian Mixture Model is a background identification algorithm that models the pixel luminance with a mixture of K Gaussian distributions. The number of Gaussian distributions determines the accuracy of the background model and the computational complexity of the algorithm. This paper compares two hardware implementations of the Gaussian Mixture Model that use three and five Gaussians per pixel. A trade off analysis is carried out by evaluating the quality of the processed video sequences and the hardware performances. The circuits are implemented on FPGA by exploiting state of the art, hardware oriented, formulation of the Gaussian Mixture Model equations and by using truncated binary multipliers. The results suggest that the circuit that uses three Gaussian distributions provides video with good accuracy while requiring significant less resources than the option that uses five Gaussian distributions per pixel.

  2. Capacity Versus Bit Error Rate Trade-Off in the DVB-S2 Forward Link

    Directory of Open Access Journals (Sweden)

    Matteo Berioli

    2007-05-01

    Full Text Available The paper presents an approach to optimize the use of satellite capacity in DVB-S2 forward links. By reducing the so-called safety margins, in the adaptive coding and modulation technique, it is possible to increase the spectral efficiency at expenses of an increased BER on the transmission. The work shows how a system can be tuned to operate at different degrees of this trade-off, and also the performance which can be achieved in terms of BER/PER, spectral efficiency, and interarrival, duration, strength of the error bursts. The paper also describes how a Markov chain can be used to model the ModCod transitions in a DVB-S2 system, and it presents results for the calculation of the transition probabilities in two cases.

  3. Capacity Versus Bit Error Rate Trade-Off in the DVB-S2 Forward Link

    Directory of Open Access Journals (Sweden)

    Berioli Matteo

    2007-01-01

    Full Text Available The paper presents an approach to optimize the use of satellite capacity in DVB-S2 forward links. By reducing the so-called safety margins, in the adaptive coding and modulation technique, it is possible to increase the spectral efficiency at expenses of an increased BER on the transmission. The work shows how a system can be tuned to operate at different degrees of this trade-off, and also the performance which can be achieved in terms of BER/PER, spectral efficiency, and interarrival, duration, strength of the error bursts. The paper also describes how a Markov chain can be used to model the ModCod transitions in a DVB-S2 system, and it presents results for the calculation of the transition probabilities in two cases.

  4. Throughput-Delay Trade-Off for Cognitive Radio Networks: A Convex Optimization Perspective

    Directory of Open Access Journals (Sweden)

    Hang Hu

    2014-01-01

    Full Text Available The throughput-delay trade-off problem for cooperative spectrum sensing (CSS is investigated. It is proved that the maximum achievable throughput and the minimum transmission delay cannot be obtained simultaneously. An efficient algorithm is proposed to optimize the sensing bandwidth and the final decision threshold jointly such that the throughput is maximized while the delay is constrained. It is demonstrated that convex optimization plays an essential role in solving the problem in an efficient way. Simulation results show that the proposed optimal scheme can significantly improve the throughput of the secondary users (SUs under the constraint that the delay Quality of Service (QoS requirements of the SUs are satisfied.

  5. Trade-offs and Opportunities in the Nexus of Energy and Water-for-Food

    Science.gov (United States)

    Rosegrant, M. W.

    2015-12-01

    The world economy is under pressure for greater, more efficient and more sustainable use of natural resources to meet complementary and competing objectives in the energy, water, and food sectors. Increasing national, regional, and seasonal water scarcities in much of the world pose severe challenges for national governments, the international development community, and ultimately, for individual water users. This presentation assesses the nexus between energy and water, with an emphasis on the interactions and trade-offs between energy and water for food production. It examines the impact of biofuel production on water quantity and quality, and the potential for hydropower potential to meet energy challenges while expanding irrigation water supplies and food production potential, thereby enhancing global food security. Biofuel production affects both water quantity and quality. Expanding production of biofuels—through either crop-based production systems or direct biomass production—can significantly increase demand for water as more acreage is planted or the crop mix begins to favor thirstier crops; water demand for bio-refineries creates additional competition with agricultural water use. Water quality can also be adversely affected by increased acreage for fertilizer-intensive crops, such as maize or sugarcane, which can result in increased nitrate run-off and soil erosion. Hydropower has become a relatively forgotten part of the energy-water security picture that deserves renewed attention. Unlike biofuels, hydropower does not normally compete with agricultural water. Instead, development of hydropower could complement food production by developing dam structures and power that also provide irrigation water and support its distribution for growing food crops. But balanced hydropower policies require consideration of potential trade-offs with environmental and social impacts.

  6. The interaction of nifedipine with selected cyclodextrins and the subsequent solubility-permeability trade-off.

    Science.gov (United States)

    Beig, Avital; Miller, Jonathan M; Dahan, Arik

    2013-11-01

    The purpose of this study was to investigate the interaction of 2-hydroxypropyl-β-cyclodextrin (HPβCD) and 2,6-dimethyl-β-cyclodextrin (DMβCD) with the lipophilic drug nifedipine and to investigate the subsequent solubility-permeability interplay. Solubility curves of nifedipine with HPβCD and DMβCD in MES buffer were evaluated using phase solubility methods. Then, the apparent permeability of nifedipine was investigated as a function of increasing HPβCD/DMβCD concentration in the hexadecane-based PAMPA model. The interaction with nifedipine was CD dependent; significantly higher stability constant was obtained for DMβCD in comparison with HPβCD. Moreover, nifedipine displays different type of interaction with these CDs; a 1:1 stoichiometric inclusion complex was apparent with HPβCD, while 1:2 stoichiometry was apparent for DMβCD. In all cases, decreased apparent intestinal permeability of nifedipine as a function of increasing CD level and nifedipine apparent solubility was obtained. A quasi-equilibrium mass transport analysis was developed to explain this solubility-permeability interplay; the model enabled excellent quantitative prediction of nifedipine's permeability as a function of CD concentrations. This work demonstrates that when using CDs in solubility-enabling formulations, a trade-off exists between solubility increase and permeability decrease that must not be overlooked. This trade-off was found to be independent of the type of CD-drug interaction. The transport model presented here can aid in striking the appropriate solubility-permeability balance in order to achieve optimal overall absorption.

  7. Revisiting the Time Trade-Off Hypothesis: Work, Organized Activities, and Academics During College.

    Science.gov (United States)

    Greene, Kaylin M; Maggs, Jennifer L

    2015-08-01

    How adolescents spend their time has long-term implications for their educational, health, and labor market outcomes, yet surprisingly little research has explored the time use of students across days and semesters. The current study used longitudinal daily diary data from a sample of college students attending a large public university in the Northeastern US (n = 726, M age = 18.4) that was followed for 14 days within each of seven semesters (for up to 98 diary days per student). The study had two primary aims. The first aim was to explore demographic correlates of employment time, organized activity time, and academic time. The second aim was to provide a rigorous test of the time trade-off hypothesis, which suggests that students will spend less time on academics when they spend more time on employment and extracurricular activities. The results demonstrated that time use varied by gender, parental education, and race/ethnicity. Furthermore, the results from multi-level models provided some support for the time trade-off hypothesis, although associations varied by the activity type and whether the day was a weekend. More time spent on employment was linked to less time spent on academics across days and semesters whereas organized activities were associated with less time on academics at the daily level only. The negative associations between employment and academics were most pronounced on weekdays. These results suggest that students may balance certain activities across days, whereas other activities may be in competition over longer time frames (i.e., semesters). PMID:25381597

  8. Biophysical and sociocultural factors underlying spatial trade-offs of ecosystem services in semiarid watersheds

    Directory of Open Access Journals (Sweden)

    Marina García-Llorente

    2015-09-01

    Full Text Available Biophysical and social systems are linked to form social-ecological systems whose sustainability depends on their capacity to absorb uncertainty and cope with disturbances. In this study, we explored the key biophysical and socio-cultural factors underlying ecosystem service supply in two semiarid watersheds of southern Spain. These included variables associated with the role that freshwater flows and biodiversity play in securing the system's capacity to sustain essential ecosystem services and their relationship with social demand for services, local water governance, and land-use intensification. Our results reveal the importance of considering the invisible dimensions of water and biodiversity, i.e. green freshwater flows and trait-based indicators, because of their relevance to the supply of ecosystem services. Furthermore, they uncover the importance of traditional irrigation canals, a local water governance system, in maintaining the ecosystems' capacity to supply services. The study also highlights the complex trade-offs that occur because of the spatial mismatch between ecosystem service supply (upstream and ecosystem service demand (downstream in watersheds. Finally, we found that land-use intensification generally resulted in losses of the biophysical factors that underpin the supply of some ecosystem services, increases in social demand for less diversified services, and the abandonment of local governance practices. Attempts to manage social-ecological systems toward sustainability at the local scale should identify the key biophysical and socio-cultural factors that are essential for maintaining ecosystem services and should recognize existing interrelationships between them. Land-use management should also take into account ecosystem service trade-offs and the consequences resulting from land-use intensification.

  9. Transcriptomic Signatures Mirror the Lack of the Fecundity/Longevity Trade-Off in Ant Queens.

    Science.gov (United States)

    von Wyschetzki, Katharina; Rueppell, Olav; Oettler, Jan; Heinze, Jürgen

    2015-12-01

    Life-history theory predicts a trade-off between reproductive investment and self-maintenance. The negative association between fertility and longevity found throughout multicellular organisms supports this prediction. As an important exception, the reproductives of many eusocial insects (ants, bees, and termites) are simultaneously very long-lived and highly fertile. Here, we examine the proximate basis for this exceptional relationship by comparing whole-body transcriptomes of differently aged queens of the ant Cardiocondyla obscurior. We show that the sets of genes differentially expressed with age significantly overlap with age-related expression changes previously found in female Drosophila melanogaster. We identified several developmental processes, such as the generation of neurons, as common signatures of aging. More generally, however, gene expression in ant queens and flies changes with age mainly in opposite directions. In contrast to flies, reproduction-associated genes were upregulated and genes associated with metabolic processes and muscle contraction were downregulated in old relative to young ant queens. Furthermore, we searched for putative C. obscurior longevity candidates associated with the previously reported lifespan-prolonging effect of mating by comparing the transcriptomes of queens that differed in mating and reproductive status. We found 21 genes, including the putative aging candidate NLaz (an insect homolog of APOD), which were consistently more highly expressed in short-lived, unmated queens than in long-lived, mated queens. Our study provides clear evidence that the alternative regulation of conserved molecular pathways that mediate the interplay among mating, egg laying, and aging underlies the lack of the fecundity/longevity trade-off in ant queens. PMID:26341296

  10. Energy technologies evaluated against climate targets using a cost and carbon trade-off curve.

    Science.gov (United States)

    Trancik, Jessika E; Cross-Call, Daniel

    2013-06-18

    Over the next few decades, severe cuts in emissions from energy will be required to meet global climate-change mitigation goals. These emission reductions imply a major shift toward low-carbon energy technologies, and the economic cost and technical feasibility of mitigation are therefore highly dependent upon the future performance of energy technologies. However, existing models do not readily translate into quantitative targets against which we can judge the dynamic performance of technologies. Here, we present a simple, new model for evaluating energy-supply technologies and their improvement trajectories against climate-change mitigation goals. We define a target for technology performance in terms of the carbon intensity of energy, consistent with emission reduction goals, and show how the target depends upon energy demand levels. Because the cost of energy determines the level of adoption, we then compare supply technologies to one another and to this target based on their position on a cost and carbon trade-off curve and how the position changes over time. Applying the model to U.S. electricity, we show that the target for carbon intensity will approach zero by midcentury for commonly cited emission reduction goals, even under a high demand-side efficiency scenario. For Chinese electricity, the carbon intensity target is relaxed and less certain because of lesser emission reductions and greater variability in energy demand projections. Examining a century-long database on changes in the cost-carbon space, we find that the magnitude of changes in cost and carbon intensity that are required to meet future performance targets is not unprecedented, providing some evidence that these targets are within engineering reach. The cost and carbon trade-off curve can be used to evaluate the dynamic performance of existing and new technologies against climate-change mitigation goals. PMID:23560987

  11. Evolution of resistance and tolerance to herbivores: testing the trade-off hypothesis

    Directory of Open Access Journals (Sweden)

    Eunice Kariñho-Betancourt

    2015-03-01

    Full Text Available Background. To cope with their natural enemies, plants rely on resistance and tolerance as defensive strategies. Evolution of these strategies among natural population can be constrained by the absence of genetic variation or because of the antagonistic genetic correlation (trade-off between them. Also, since plant defenses are integrated by several traits, it has been suggested that trade-offs might occur between specific defense traits. Methodology/Principal Findings. We experimentally assessed (1 the presence of genetic variance in tolerance, total resistance, and leaf trichome density as specific defense trait, (2 the extent of natural selection acting on plant defenses, and (3 the relationship between total resistance and leaf trichome density with tolerance to herbivory in the annual herb Datura stramonium. Full-sib families of D. stramonium were either exposed to natural herbivores (control or protected from them by a systemic insecticide. We detected genetic variance for leaf trichome density, and directional selection acting on this character. However, we did not detect a negative significant correlation between tolerance and total resistance, or between tolerance and leaf trichome density. We argue that low levels of leaf damage by herbivores precluded the detection of a negative genetic correlation between plant defense strategies. Conclusions/Significance. This study provides empirical evidence of the independent evolution of plant defense strategies, and a defensive role of leaf trichomes. The pattern of selection should favor individuals with high trichomes density. Also, because leaf trichome density reduces damage by herbivores and possess genetic variance in the studied population, its evolution is not constrained.

  12. Reproductive effort and the egg number vs. size trade-off in Physalaemus frogs (Anura: Leiuperidae)

    Science.gov (United States)

    Camargo, Arley; Sarroca, Macarena; Maneyro, Raúl

    2008-09-01

    Patterns of reproductive allocation are expected to differ between species according to temporally and spatially variable costs of reproduction. Even when reproductive allocation patterns are the same, species can also differ in how the reproductive effort is allocated between offspring number and size. In this study, we compared the reproductive allocation patterns and the offspring number vs. size trade-off in two frog species, Physalaemus biligonigerus and P. gracilis, using bivariate (standardized major axis) and multiple linear regressions. Both species showed a common slope between body size and reproductive effort and thus a similar allocation pattern although P. biligonigerus has a larger body size (shift along common slope) and makes a lower reproductive effort (shift in intercept) than P. gracilis. We suggest that similar allocation patterns may be related to the shared phenologies of these frogs and that the differences in reproductive effort could represent either an adaptive shift (e.g., change in body space for the clutch) or a historical constraint. There was a negative correlation between fecundity and egg size in P. biligonigerus but not in P. gracilis as predicted by the acquisition-allocation model (Y-model). This study constitutes the first valid test of the Y-model based on recent predictions derived for the trade-off between offspring size vs. number. We conclude that future studies should compare reproductive allocation patterns between species using tests of allometric slopes with appropriate phylogenetic control to detect both adaptive shifts in allocation strategies and correlations with other life-history traits.

  13. Multi-ASIP Platform Synthesis for Event-Triggered Applications with Cost/Performance Trade-offs

    DEFF Research Database (Denmark)

    Gangadharan, Deepak; Micconi, Laura; Pop, Paul;

    2013-01-01

    the overall cost of the platform. We propose an area estimation model and a WCET uncertainty model that consider the effect of task datapath similarity. Based on these two models, we support the designer in exploring cost/performance trade-offs during the platform synthesis. We propose an Evolutionary...... Algorithm-based approach to solve this multiobjective optimization problem. The proposed approach has been evaluated using several benchmarks and it provides a number of multi-ASIP platform solutions exploring the trade-offs in the cost/performance design space....

  14. Comparative impacts of temperature and trade-offs on egg ecology of north Atlantic pelagic fish species

    DEFF Research Database (Denmark)

    Tsoukali, Stavroula; MacKenzie, Brian

    . We collated development and survival data from publications on laboratory egg incubation experiments to investigate and compare the development, daily mortality and survival of fish eggs from pelagic species in the north Atlantic at different temperatures, and to investigate whether trade-offs exist...... between these traits at the population and species level and between habitat types (pelagic and demersal). While differing in magnitude, the response of these traits exhibited similar trends with respect to temperature, regardless of species, population or habitat type. A trade-off appears between rapid...

  15. Trade-Offs between Growth Rate, Tree Size and Lifespan of Mountain Pine (Pinus montana) in the Swiss National Park.

    Science.gov (United States)

    Bigler, Christof

    2016-01-01

    A within-species trade-off between growth rates and lifespan has been observed across different taxa of trees, however, there is some uncertainty whether this trade-off also applies to shade-intolerant tree species. The main objective of this study was to investigate the relationships between radial growth, tree size and lifespan of shade-intolerant mountain pines. For 200 dead standing mountain pines (Pinus montana) located along gradients of aspect, slope steepness and elevation in the Swiss National Park, radial annual growth rates and lifespan were reconstructed. While early growth (i.e. mean tree-ring width over the first 50 years) correlated positively with diameter at the time of tree death, a negative correlation resulted with lifespan, i.e. rapidly growing mountain pines face a trade-off between reaching a large diameter at the cost of early tree death. Slowly growing mountain pines may reach a large diameter and a long lifespan, but risk to die young at a small size. Early growth was not correlated with temperature or precipitation over the growing period. Variability in lifespan was further contingent on aspect, slope steepness and elevation. The shade-intolerant mountain pines follow diverging growth trajectories that are imposed by extrinsic environmental influences. The resulting trade-offs between growth rate, tree size and lifespan advance our understanding of tree population dynamics, which may ultimately improve projections of forest dynamics under changing environmental conditions.

  16. Trade-Offs between Growth Rate, Tree Size and Lifespan of Mountain Pine (Pinus montana in the Swiss National Park.

    Directory of Open Access Journals (Sweden)

    Christof Bigler

    Full Text Available A within-species trade-off between growth rates and lifespan has been observed across different taxa of trees, however, there is some uncertainty whether this trade-off also applies to shade-intolerant tree species. The main objective of this study was to investigate the relationships between radial growth, tree size and lifespan of shade-intolerant mountain pines. For 200 dead standing mountain pines (Pinus montana located along gradients of aspect, slope steepness and elevation in the Swiss National Park, radial annual growth rates and lifespan were reconstructed. While early growth (i.e. mean tree-ring width over the first 50 years correlated positively with diameter at the time of tree death, a negative correlation resulted with lifespan, i.e. rapidly growing mountain pines face a trade-off between reaching a large diameter at the cost of early tree death. Slowly growing mountain pines may reach a large diameter and a long lifespan, but risk to die young at a small size. Early growth was not correlated with temperature or precipitation over the growing period. Variability in lifespan was further contingent on aspect, slope steepness and elevation. The shade-intolerant mountain pines follow diverging growth trajectories that are imposed by extrinsic environmental influences. The resulting trade-offs between growth rate, tree size and lifespan advance our understanding of tree population dynamics, which may ultimately improve projections of forest dynamics under changing environmental conditions.

  17. Modeling trade-offs between plant fiber and toxins: a framework for quantifying risks perceived by foraging herbivores.

    Science.gov (United States)

    Camp, Meghan J; Shipley, Lisa A; Johnson, Timothy R; Forbey, Jennifer Sorensen; Rachlow, Janet L; Crowell, Miranda M

    2015-12-01

    When selecting habitats, herbivores must weigh multiple risks, such as predation, starvation, toxicity, and thermal stress, forcing them to make fitness trade-offs. Here, we applied the method of paired comparisons (PC) to investigate how herbivores make trade-offs between habitat features that influence selection of food patches. The method of PC measures utility and the inverse of utility, relative risk, and makes trade-offs and indifferences explicit by forcing animals to make choices between two patches with different types of risks. Using a series of paired-choice experiments to titrate the equivalence curve and find the marginal rate of substitution for one risk over the other, we evaluated how toxin-tolerant (pygmy rabbit Brachylagus idahoensis) and fiber-tolerant (mountain cottontail rabbit Sylviagus nuttallii) herbivores differed in their hypothesized perceived risk of fiber and toxins in food. Pygmy rabbits were willing to consume nearly five times more of the toxin 1,8-cineole in their diets to avoid consuming higher levels of fiber than were mountain cottontails. Fiber posed a greater relative risk for pygmy rabbits than cottontails and cineole a greater risk for cottontails than pygmy rabbits. Our flexible modeling approach can be used to (1) quantify how animals evaluate and trade off multiple habitat attributes when the benefits and risks are difficult to quantify, and (2) integrate diverse risks that influence fitness and habitat selection into a single index of habitat value. This index potentially could be applied to landscapes to predict habitat selection across several scales.

  18. Proceedings 5th Symposium on Resilience Engineering, Managing trade-offs; 24th-27th June 2013 Soesterberg, Netherlands

    NARCIS (Netherlands)

    Herrera, I.; Schraagen, J.M.C.; Vorm, J. van der; Woods, D.D.

    2014-01-01

    The 5th Symposium continued this tradition and was organized by TNO around the theme of ‘Resilience Engineering: Managing Trade-offs,’ and brought together 140 researchers and practitioners from diverse disciplines, multiple industry sectors and about 20 countries. The program addressed the challeng

  19. Trade-Offs between Growth Rate, Tree Size and Lifespan of Mountain Pine (Pinus montana) in the Swiss National Park

    Science.gov (United States)

    Bigler, Christof

    2016-01-01

    A within-species trade-off between growth rates and lifespan has been observed across different taxa of trees, however, there is some uncertainty whether this trade-off also applies to shade-intolerant tree species. The main objective of this study was to investigate the relationships between radial growth, tree size and lifespan of shade-intolerant mountain pines. For 200 dead standing mountain pines (Pinus montana) located along gradients of aspect, slope steepness and elevation in the Swiss National Park, radial annual growth rates and lifespan were reconstructed. While early growth (i.e. mean tree-ring width over the first 50 years) correlated positively with diameter at the time of tree death, a negative correlation resulted with lifespan, i.e. rapidly growing mountain pines face a trade-off between reaching a large diameter at the cost of early tree death. Slowly growing mountain pines may reach a large diameter and a long lifespan, but risk to die young at a small size. Early growth was not correlated with temperature or precipitation over the growing period. Variability in lifespan was further contingent on aspect, slope steepness and elevation. The shade-intolerant mountain pines follow diverging growth trajectories that are imposed by extrinsic environmental influences. The resulting trade-offs between growth rate, tree size and lifespan advance our understanding of tree population dynamics, which may ultimately improve projections of forest dynamics under changing environmental conditions. PMID:26930294

  20. Sustainability of pasture-based livestock farming systems in the European Mediterranean context: Synergies and trade-offs

    NARCIS (Netherlands)

    Bernués, A.; Ruiz, R.; Olaizola, A.; Villalba, D.; Casasús, I.

    2011-01-01

    The sustainability of livestock farming systems (LFS) in relation to global concerns about climate change, population dynamics and the quality of the agro-ecosystem services that are provided to society and their trade-offs has become a fundamental issue for public and scientific debate. However, LF

  1. The Pecking Order, Trade-off, Signaling, and Market-Timing Theories of Capital Structure: a Review

    OpenAIRE

    Miglo, Anton

    2010-01-01

    This paper surveys 4 major capital structure theories: trade-off, pecking order, signaling and market timing. For each theory, a basic model and its major implications are presented. These implications are compared to the available evidence. This is followed by an overview of pros and cons for each theory. A discussion of major recent papers and suggestions for future research are provided.

  2. The trade-off between money and time: A test of the theory of reference-dependent preferences

    DEFF Research Database (Denmark)

    De Borger, Bruno; Fosgerau, Mogens

    2008-01-01

    We formulate a model of reference-dependent preferences based on the marginal rate of substitution at the reference-point of a reference-free utility function. Using binary choices on the trade-off between money and travel time, reference-dependence is captured by value functions that are centered...

  3. Genomic evidence that resource-based trade-offs limit host-range expansion in a seed beetle.

    Science.gov (United States)

    Gompert, Zachariah; Messina, Frank J

    2016-06-01

    Trade-offs have often been invoked to explain the evolution of ecological specialization. Phytophagous insects have been especially well studied, but there has been little evidence that resource-based trade-offs contribute to the evolution of host specialization in this group. Here, we combine experimental evolution and partial genome resequencing of replicate seed beetle selection lines to test the trade-off hypothesis and measure the repeatability of evolution. Bayesian estimates of selection coefficients suggest that rapid adaptation to a poor host (lentil) was mediated by standing genetic variation at multiple genetic loci and involved many of the same variants in replicate lines. Sublines that were then switched back to the ancestral host (mung bean) showed a more gradual and variable (less repeatable) loss of adaptation to lentil. We were able to obtain estimates of variance effective population sizes from genome-wide differences in allele frequencies within and between lines. These estimates were relatively large, which suggests that the contribution of genetic drift to the loss of adaptation following reversion was small. Instead, we find that some alleles that were favored on lentil were selected against during reversion on mung bean, consistent with the genetic trade-off hypothesis. PMID:27130550

  4. Trade-off between migration and reproduction : does a high workload affect body condition and reproductive state?

    NARCIS (Netherlands)

    Schmidt-Wellenburg, Carola A.; Visser, G. Henk; Biebach, Brigitte; Delhey, Kaspar; Oltrogge, Martina; Wittenzellner, Andrea; Biebach, Herbert; Kempenaers, Bart

    2008-01-01

    Migratory birds have to invest much energy into flight to reach their summer and winter quarters. Many studies have shown how migration affects body physiology, including the accumulation of energy stores and the reduction of nonessential organs. In spring, the costs of migration may trade-off with

  5. Local above-ground persistence of vascular plants : Life-history trade-offs and environmental constraints

    NARCIS (Netherlands)

    Ozinga, Wim A.; Hennekens, Stephan M.; Schaminee, Joop H. J.; Smits, Nina A. C.; Bekker, Renee M.; Roemermann, Christine; Klimes, Leos; Bakker, Jan P.; van Groenendael, Jan M.

    2007-01-01

    Questions: 1. Which plant traits and habitat characteristics best explain local above-ground persistence of vascular plant species and 2. Is there a trade-off between local above-ground persistence and the ability for seed dispersal and below-ground persistence in the soil seed bank? Locations: 845

  6. Local above-ground persistence of vascular plants: life-history trade-offs and environmental constraints

    NARCIS (Netherlands)

    Ozinga, W.A.; Hennekens, S.M.; Schaminée, J.H.J.; Smits, N.A.C.; Bekker, R.M.; Römermann, C.; Bakker, J.P.; Groenendael, van J.M.

    2007-01-01

    Questions: 1. Which plant traits and habitat characteristics best explain local above-ground persistence of vascular plant species and 2. Is there a trade-off between local above-ground persistence and the ability for seed dispersal and below-ground persistence in the soil seed bank? Locations: 845

  7. Correction: Viruses' Life History: Towards a Mechanistic Basis of a Trade-Off between Survival and Reproduction among Phages.

    Directory of Open Access Journals (Sweden)

    François Taddei

    2006-08-01

    Full Text Available A comparison of life-history traits of 16 phages infecting E. coli reveals that although these viruses don't age, there is a trade-off between mortality and growth rate, which parallels that observed in many other species.

  8. Correction: Viruses' Life History: Towards a Mechanistic Basis of a Trade-Off between Survival and Reproduction among Phages

    OpenAIRE

    Taddei, François; De Paepe, Marianne

    2006-01-01

    A comparison of life-history traits of 16 phages infecting E. coli reveals that although these viruses don't age, there is a trade-off between mortality and growth rate, which parallels that observed in many other species.

  9. Correction: Viruses' Life History: Towards a Mechanistic Basis of a Trade-Off between Survival and Reproduction among Phages.

    OpenAIRE

    François Taddei; Marianne De Paepe

    2006-01-01

    A comparison of life-history traits of 16 phages infecting E. coli reveals that although these viruses don't age, there is a trade-off between mortality and growth rate, which parallels that observed in many other species.

  10. Incentivising flood risk adaptation through risk based insurance premiums : Trade-offs between affordability and risk reduction

    NARCIS (Netherlands)

    Hudson, Paul F.; Botzen, W.J.W.; Feyen, L.; Aerts, Jeroen C.J.H.

    2016-01-01

    The financial incentives offered by the risk-based pricing of insurance can stimulate policyholder adaptation to flood risk while potentially conflicting with affordability. We examine the trade-off between risk reduction and affordability in a model of public-private flood insurance in France and G

  11. Anticipating and Managing Future Trade-offs and Complementarities between Ecosystem Services

    Directory of Open Access Journals (Sweden)

    Mark S. Reed

    2013-03-01

    Full Text Available This paper shows how, with the aid of computer models developed in close collaboration with decision makers and other stakeholders, it is possible to quantify and map how policy decisions are likely to affect multiple ecosystem services in future. In this way, potential trade-offs and complementarities between different ecosystem services can be identified, so that policies can be designed to avoid the worst trade-offs, and where possible, enhance multiple services. The paper brings together evidence from across the Rural Economy and Land Use Programme's Sustainable Uplands project for the first time, with previously unpublished model outputs relating to runoff, agricultural suitability, biomass, heather cover, age, and utility for Red Grouse (Lagopus scotica, grass cover, and accompanying scenario narratives and video. Two contrasting scenarios, based on policies to extensify or intensify land management up to 2030, were developed through a combination of interviews and discussions during site visits with stakeholders, literature review, conceptual modeling, and process-based computer models, using the Dark Peak of the Peak District National Park in the UK as a case study. Where extensification leads to a significant reduction in managed burning and grazing or land abandonment, changes in vegetation type and structure could compromise a range of species that are important for conservation, while compromising provisioning services, amenity value, and increasing wildfire risk. However, where extensification leads to the restoration of peatlands damaged by former intensive management, there would be an increase in carbon sequestration and storage, with a number of cobenefits, which could counter the loss of habitats and species elsewhere in the landscape. In the second scenario, land use and management was significantly intensified to boost UK self-sufficiency in food. This would benefit certain provisioning services but would have negative

  12. Dealing with food and eggs in mouthbrooding cichlids: structural and functional trade-offs in fitness related traits.

    Directory of Open Access Journals (Sweden)

    Tim Tkint

    Full Text Available BACKGROUND: As in any vertebrate, heads of fishes are densely packed with functions. These functions often impose conflicting mechanical demands resulting in trade-offs in the species-specific phenotype. When phenotypical traits are linked to gender-specific parental behavior, we expect sexual differences in these trade-offs. This study aims to use mouthbrooding cichlids as an example to test hypotheses on evolutionary trade-offs between intricately linked traits that affect different aspects of fitness. We focused on the oral apparatus, which is not only equipped with features used to feed and breathe, but is also used for the incubation of eggs. We used this approach to study mouthbrooding as part of an integrated functional system with diverging performance requirements and to explore gender-specific selective environments within a species. METHODOLOGY/PRINCIPAL FINDINGS: Because cichlids are morphologically very diverse, we hypothesize that the implications of the added constraint of mouthbrooding will primarily depend on the dominant mode of feeding of the studied species. To test this, we compared the trade-off for two maternal mouthbrooding cichlid species: a "suction feeder" (Haplochromis piceatus and a "biter" (H. fischeri. The comparison of morphology and performance of both species revealed clear interspecific and intersex differences. Our observation that females have larger heads was interpreted as a possible consequence of the fact that in both the studied species mouthbrooding is done by females only. As hypothesized, the observed sexual dimorphism in head shape is inferred as being suboptimal for some aspects of the feeding performance in each of the studied species. Our comparison also demonstrated that the suction feeding species had smaller egg clutches and more elongated eggs. CONCLUSIONS/SIGNIFICANCE: Our findings support the hypothesis that there is a trade-off between mouthbrooding and feeding performance in the two

  13. Analysing trade-offs in resource and labour allocation by smallholder farmers using inverse modelling techniques: a case-study from Kakamega district, western Kenya

    NARCIS (Netherlands)

    Tittonell, P.A.; Wijk, van M.T.; Rufino, M.C.; Vrugt, J.A.; Giller, K.E.

    2007-01-01

    Smallholder farms in sub-Saharan Africa face multiple trade-offs when deciding on the allocation of their financial, labour and nutrient resources. Day-to-day decisions have implications for the sustainability of their farming system, implying multiple trade-offs between short- and long-term objecti

  14. Development of a model for the prediction of the fuel consumption and nitrogen oxides emission trade-off for large ships

    DEFF Research Database (Denmark)

    Larsen, Ulrik; Pierobon, Leonardo; Baldi, Francesco;

    2015-01-01

    consideration of this trade-off mechanism is required in the design of marine propulsion systems. This study investigates five different configurations of two-stroke diesel-based machinery systems for large ships and their influence on the mentioned trade-off. Numerical models of a low-speed two-stroke diesel...

  15. Emotion and Attention Interaction: a trade-off between stimuli relevance, motivation and individual differences

    Directory of Open Access Journals (Sweden)

    Leticia eOliveira

    2013-07-01

    Full Text Available Mounting evidence suggests that the neural processing of emotional stimuli is prioritized. However, whether the processing of emotional stimuli is dependent on attention remains debatable. Several studies have investigated this issue by testing the capacity of emotional distracters to divert processing resources from an attentional main task. The attentional load theory postulates that the perceptual load of the main task determines the selective processing of the distracter. Although we agree with this theory, we also suggest that other factors could be important in determining the association between the load of the main task and distracter processing, namely, (1 the relevance of the to-be ignored stimuli and (2 the engagement in the main task resulting from motivation. We postulate that these factors function as opposite forces to influence distracter processing. In addition, we propose that this trade-off is modulated by individual differences. In summary, we suggest that the relationship between emotion and attention is flexible rather than rigid and depends on several factors. Considering this perspective may help us to understand the divergence in the results described by several studies in this field.

  16. Within-Host Niche Differences and Fitness Trade-offs Promote Coexistence of Plant Viruses.

    Science.gov (United States)

    Mordecai, Erin A; Gross, Kevin; Mitchell, Charles E

    2016-01-01

    Pathogens live in diverse, competitive communities, yet the processes that maintain pathogen diversity remain elusive. Here, we use a species-rich, well-studied plant virus system, the barley yellow dwarf viruses, to examine the mechanisms that regulate pathogen diversity. We empirically parameterized models of three viruses, their two aphid vectors, and one perennial grass host. We found that high densities of both aphids maximized virus diversity and that competition limited the coexistence of two closely related viruses. Even limited ability to simultaneously infect (coinfect) host individuals strongly promoted virus coexistence; preventing coinfection led to priority effects. Coinfection generated stabilizing niche differences by allowing viruses to share hosts. However, coexistence also required trade-offs between vector generalist and specialist life-history strategies. Our predicted outcomes broadly concur with previous field observations. These results show how competition within individual hosts and vectors may lead to unexpected population-level outcomes between pathogens, including coexistence, competitive exclusion, and priority effects, and how contemporary coexistence theory can help to predict these outcomes. PMID:27277413

  17. Trade-offs between spatial and temporal resolutions in stochastic super-resolution microscopy techniques

    CERN Document Server

    Rupprecht, Jean-Francois; Tessier, Gilles

    2016-01-01

    Widefield stochastic microscopy techniques such as PALM or STORM rely on the progressive accumulation of a large number of frames, each containing a scarce number of super-resolved point images. We justify that the redundancy in the localization of detected events imposes a specific limit on the temporal resolution. Based on a theoretical model, we derive analytical predictions for the minimal time required to obtain a reliable image at a given spatial resolution, called image completion time. In contrast to standard assumptions, we find that the image completion time scales logarithmically with the ratio of the image size by the spatial resolution volume. We justify that this non-linear relation is the hallmark of a random coverage problem. We propose a method to estimate the risk that the image reconstruction is not complete, which we apply to an experimental data set. Our results provide a theoretical framework to quantify the pattern detection efficiency and to optimize the trade-off between image coverag...

  18. A computational analysis of stoichiometric constraints and trade-offs in cyanobacterial biofuel production

    Directory of Open Access Journals (Sweden)

    Henning eKnoop

    2015-04-01

    Full Text Available Cyanobacteria are a promising biological chassis for the synthesis of renewable fuels and chemical bulk commodities.Significant efforts have been devoted to improve the yields of cyanobacterial products. However, while the introduction and heterologous expression of product-forming pathways is often feasible, the interactions and incompatibilities of product synthesis with the host metabolism are still insufficiently understood.In this work, we investigate the stoichiometric properties and trade-offs that underlie cyanobacterial product formation using a computational reconstruction of cyanobacterial metabolism. First, we evaluate the synthesis requirements of a selection of cyanobacterial products of potential biotechnological interest. Second, the large-scale metabolic reconstruction allows us toperform in-silico experiments that mimic and predict the metabolic changes that must occur in the transition from a growth-only phenotype to a production-only phenotype. Applied to the synthesis of ethanol, ethylene, and propane, these in-silico transition experiments point to bottlenecks and potential modification targets in cyanobacterial metabolism.Our analysis reveals incompatibilities between biotechnological product synthesis and native host metabolism, such as shifts in ATP/NADPH demand and the requirement to reintegrate metabolic by-products. Similar strategies can be employed for a large class of cyanobacterial products to identify potential stoichiometric bottlenecks.

  19. Trade-offs between life-history traits at range-edge and central locations.

    Science.gov (United States)

    Araújo, Rita; Serrão, Ester A; Sousa-Pinto, Isabel; Arenas, Francisco; Monteiro, Carla A; Toth, Gunilla; Pavia, Henrik; Åberg, Per

    2015-08-01

    The allocation of resources to different life-history traits should represent the best compromise in fitness investment for organisms in their local environment. When resources are limiting, the investment in a specific trait must carry a cost that is expressed in trade-offs with other traits. In this study, the relative investment in the fitness-related traits, growth, reproduction and defence were compared at central and range-edge locations, using the seaweed Ascophyllum nodosum as a model system. Individual growth rates were similar at both sites, whereas edge populations showed a higher relative investment in reproduction (demonstrated by a higher reproductive allocation and extended reproductive periods) when compared to central populations that invested more in defence. These results show the capability of A. nodosum to differentially allocate resources for different traits under different habitat conditions, suggesting that reproduction and defence have different fitness values under the specific living conditions experienced at edge and central locations. However, ongoing climate change may threaten edge populations by increasing the selective pressure on specific traits, forcing these populations to lower the investment in other traits that are also potentially important for population fitness. PMID:26986798

  20. 85Kr management trade-offs: a perspective to total radiation dose commitment

    Energy Technology Data Exchange (ETDEWEB)

    Mellinger, P.J.; Hoenes, G.R.; Brackenbush, L.W.; Greenborg, J.

    1980-01-01

    Radiological consequences arising from the trade-offs for /sup 85/Kr waste management from possible nuclear fuel resource recovery activities have been investigated. The reference management technique is to release all the waste gas to the atmosphere where it is diluted and dispersed. A potential alternative is to collect, concentrate, package and submit the gas to long-term storage. This study compares the radiation dose commitment to the public and to the occupationally exposed work force from these alternatives. The results indicate that it makes little difference to the magnitude of the world population dose whether /sup 85/Kr is captured and stored or chronically released to the environment. Further, comparisons of radiation exposures (for the purpose of estimating health effects) at very low dose rates to very large populations with exposures to a small number of occupationally exposed workers who each receive much higher dose rates may be misleading. Finally, cost studies (EPA 1976 and DOE 1979a) show that inordinate amounts of money will be required to lower this already extremely small 80-year cumulative world population dose of 0.05 mrem/person (<0.001% of natural background radiation for the same time period).

  1. Viral Genome Segmentation Can Result from a Trade-Off between Genetic Content and Particle Stability

    Science.gov (United States)

    Ojosnegros, Samuel; García-Arriaza, Juan; Escarmís, Cristina; Manrubia, Susanna C.; Perales, Celia; Arias, Armando; Mateu, Mauricio García; Domingo, Esteban

    2011-01-01

    The evolutionary benefit of viral genome segmentation is a classical, yet unsolved question in evolutionary biology and RNA genetics. Theoretical studies anticipated that replication of shorter RNA segments could provide a replicative advantage over standard size genomes. However, this question has remained elusive to experimentalists because of the lack of a proper viral model system. Here we present a study with a stable segmented bipartite RNA virus and its ancestor non-segmented counterpart, in an identical genomic nucleotide sequence context. Results of RNA replication, protein expression, competition experiments, and inactivation of infectious particles point to a non-replicative trait, the particle stability, as the main driver of fitness gain of segmented genomes. Accordingly, measurements of the volume occupation of the genome inside viral capsids indicate that packaging shorter genomes involves a relaxation of the packaging density that is energetically favourable. The empirical observations are used to design a computational model that predicts the existence of a critical multiplicity of infection for domination of segmented over standard types. Our experiments suggest that viral segmented genomes may have arisen as a molecular solution for the trade-off between genome length and particle stability. Genome segmentation allows maximizing the genetic content without the detrimental effect in stability derived from incresing genome length. PMID:21437265

  2. Trade-Offs in Resource Allocation Among Moss Species Control Decomposition in Boreal Peatlands

    Energy Technology Data Exchange (ETDEWEB)

    Turetsky, M. R.; Crow, S. E.; Evans, R. J.; Vitt, D. H.; Wieder, R. K.

    2008-01-01

    We separated the effects of plant species controls on decomposition rates from environmental controls in northern peatlands using a full factorial, reciprocal transplant experiment of eight dominant bryophytes in four distinct peatland types in boreal Alberta, Canada. Standard fractionation techniques as well as compound-specific pyrolysis molecular beam mass spectrometry were used to identify a biochemical mechanism underlying any interspecific differences in decomposition rates. We found that over a 3-year field incubation, individual moss species and not micro-environmental conditions controlled early stages of decomposition. Across species, Sphagnum mosses exhibited a trade-off in resource partitioning into metabolic and structural carbohydrates, a pattern that served as a strong predictor of litter decomposition. Decomposition rates showed a negative co-variation between species and their microtopographic position, as species that live in hummocks decomposed slowly but hummock microhabitats themselves corresponded to rapid decomposition rates. By forming litter that degrades slowly, hummock mosses appear to promote the maintenance of macropore structure in surface peat hummocks that aid in water retention. Many northern regions are experiencing rapid climate warming that is expected to accelerate the decomposition of large soil carbon pools stored within peatlands. However, our results suggest that some common peatland moss species form tissue that resists decomposition across a range of peatland environments, suggesting that moss resource allocation could stabilize peatland carbon losses under a changing climate.

  3. Trade-Offs of Escherichia coli Adaptation to an Intracellular Lifestyle in Macrophages

    Science.gov (United States)

    Thompson, J. A.; Proença, J. T.; Gordo, I.

    2016-01-01

    The bacterium Escherichia coli exhibits remarkable genomic and phenotypic variation, with some pathogenic strains having evolved to survive and even replicate in the harsh intra-macrophage environment. The rate and effects of mutations that can cause pathoadaptation are key determinants of the pace at which E. coli can colonize such niches and become pathogenic. We used experimental evolution to determine the speed and evolutionary paths undertaken by a commensal strain of E. coli when adapting to intracellular life. We estimated the acquisition of pathoadaptive mutations at a rate of 10−6 per genome per generation, resulting in the fixation of more virulent strains in less than a hundred generations. Whole genome sequencing of independently evolved clones showed that the main targets of intracellular adaptation involved loss of function mutations in genes implicated in the assembly of the lipopolysaccharide core, iron metabolism and di- and tri-peptide transport, namely rfaI, fhuA and tppB, respectively. We found a substantial amount of antagonistic pleiotropy in evolved populations, as well as metabolic trade-offs, commonly found in intracellular bacteria with reduced genome sizes. Overall, the low levels of clonal interference detected indicate that the first steps of the transition of a commensal E. coli into intracellular pathogens are dominated by a few pathoadaptive mutations with very strong effects. PMID:26752723

  4. Power/Performance Trade-offs of Small Batched LU Based Solvers on GPUs

    Energy Technology Data Exchange (ETDEWEB)

    Villa, Oreste; Fatica, Massimiliano; Gawande, Nitin A.; Tumeo, Antonino

    2013-08-26

    In this paper we propose and analyze a set of batched linear solvers for small matrices on Graphic Processing Units (GPUs), evaluating the various alternatives depending on the size of the systems to solve. We discuss three different solutions that operate with different level of parallelization and GPU features. The first, exploiting the CUBLAS library, manages matrices of size up to 32x32 and employs Warp level (one matrix, one Warp) parallelism and shared memory. The second works at Thread-block level parallelism (one matrix, one Thread-block), still exploiting shared memory but managing matrices up to 76x76. The third is Thread level parallel (one matrix, one thread) and can reach sizes up to 128x128, but it does not exploit shared memory and only relies on the high memory bandwidth of the GPU. The first and second solution only support partial pivoting, the third one easily supports partial and full pivoting, making it attractive to problems that require greater numerical stability. We analyze the trade-offs in terms of performance and power consumption as function of the size of the linear systems that are simultaneously solved. We execute the three implementations on a Tesla M2090 (Fermi) and on a Tesla K20 (Kepler).

  5. Cost-benefit trade-offs of bird activity in apple orchards

    Science.gov (United States)

    Saunders, Manu E.; Luck, Gary W.

    2016-01-01

    Birds active in apple orchards in south–eastern Australia can contribute positively (e.g., control crop pests) or negatively (e.g., crop damage) to crop yields. Our study is the first to identify net outcomes of these activities, using six apple orchards, varying in management intensity, in south–eastern Australia as a study system. We also conducted a predation experiment using real and artificial codling moth (Cydia pomonella) larvae (a major pest in apple crops). We found that: (1) excluding birds from branches of apple trees resulted in an average of 12.8% more apples damaged by insects; (2) bird damage to apples was low (1.9% of apples); and (3) when trading off the potential benefits (biological control) with costs (bird damage to apples), birds provided an overall net benefit to orchard growers. We found that predation of real codling moth larvae was higher than for plasticine larvae, suggesting that plasticine prey models are not useful for inferring actual predation levels. Our study shows how complex ecological interactions between birds and invertebrates affect crop yield in apples, and provides practical strategies for improving the sustainability of orchard systems. PMID:27413639

  6. Biofuels from pyrolysis in perspective: trade-offs between energy yields and soil-carbon additions.

    Science.gov (United States)

    Woolf, Dominic; Lehmann, Johannes; Fisher, Elizabeth M; Angenent, Largus T

    2014-06-01

    Coproduction of biofuels with biochar (the carbon-rich solid formed during biomass pyrolysis) can provide carbon-negative bioenergy if the biochar is sequestered in soil, where it can improve fertility and thus simultaneously address issues of food security, soil degradation, energy production, and climate change. However, increasing biochar production entails a reduction in bioenergy obtainable per unit biomass feedstock. Quantification of this trade-off for specific biochar-biofuel pathways has been hampered by lack of an accurate-yet-simple model for predicting yields, product compositions, and energy balances from biomass slow pyrolysis. An empirical model of biomass slow pyrolysis was developed and applied to several pathways for biochar coproduction with gaseous and liquid biofuels. Here, we show that biochar production reduces liquid biofuel yield by at least 21 GJ Mg(-1) C (biofuel energy sacrificed per unit mass of biochar C), with methanol synthesis giving this lowest energy penalty. For gaseous-biofuel production, the minimum energy penalty for biochar production is 33 GJ Mg(-1) C. These substitution rates correspond to a wide range of Pareto-optimal system configurations, implying considerable latitude to choose pyrolysis conditions to optimize for desired biochar properties or to modulate energy versus biochar yields in response to fluctuating price differentials for the two commodities.

  7. How Should China Handle Trade-offs between Growth and Inflation?

    Institute of Scientific and Technical Information of China (English)

    张晓晶

    2008-01-01

    This article first presents an analysis of the two most important macro variables: inflation and growth. In respect to inflation that faces a daunting landscape at the present time, China can still hold the inflation rate at an appropriate level in 2008. In consideration to a world economic slowdown and primary goods price trends as well as domestic price hikes and production overcapacity, inflation should be able to be kept in check in 2008. In regards to growth, this article employs the Phillips curve equation to arrive at a potential growth rate of 9.4% for China in 2008. Over the next couple of decades, however, the potential growth rate is projected to decline. Subsequently, this article discusses the challenges facing the tightening monetary policy: the trade-off between growth and inflation, the quagmire of liquidity control, the different interest rate movement episodes of China and the Unites States at different stages of economic cycles, and the temporary expediency nature of taming inflation through currency appreciation. Nevertheless, monetary policy still has a positive role to play and China should remain steadfast in pursuing monetary austerity policies. Last but not least, the article presents an outlook for the future.

  8. Trade-Offs of Escherichia coli Adaptation to an Intracellular Lifestyle in Macrophages.

    Directory of Open Access Journals (Sweden)

    M Azevedo

    Full Text Available The bacterium Escherichia coli exhibits remarkable genomic and phenotypic variation, with some pathogenic strains having evolved to survive and even replicate in the harsh intra-macrophage environment. The rate and effects of mutations that can cause pathoadaptation are key determinants of the pace at which E. coli can colonize such niches and become pathogenic. We used experimental evolution to determine the speed and evolutionary paths undertaken by a commensal strain of E. coli when adapting to intracellular life. We estimated the acquisition of pathoadaptive mutations at a rate of 10-6 per genome per generation, resulting in the fixation of more virulent strains in less than a hundred generations. Whole genome sequencing of independently evolved clones showed that the main targets of intracellular adaptation involved loss of function mutations in genes implicated in the assembly of the lipopolysaccharide core, iron metabolism and di- and tri-peptide transport, namely rfaI, fhuA and tppB, respectively. We found a substantial amount of antagonistic pleiotropy in evolved populations, as well as metabolic trade-offs, commonly found in intracellular bacteria with reduced genome sizes. Overall, the low levels of clonal interference detected indicate that the first steps of the transition of a commensal E. coli into intracellular pathogens are dominated by a few pathoadaptive mutations with very strong effects.

  9. Better powder diffractometers-choice of beam elements and trade-offs in design

    Energy Technology Data Exchange (ETDEWEB)

    Cussen, L.D. [Cussen Consulting, 4 Bluebell Court, Berwick, Victoria 3806 (Australia)]. E-mail: ldcussen@optusnet.com.au

    2005-12-01

    This article re-examines the equations governing resolution on constant wavelength neutron powder diffractometers (PDs) as cast for Gaussian elements. There is a widely accepted choice of collimators and monochromator mosaic to maximise peak intensity for a given resolution on high-resolution PDs. A second distinct 'optimisation' was found more recently by an acceptance diagram study. This article shows that these 'optimisations' are only two of an infinite number of equivalent element choices. A procedure to find these equivalent configurations is given. This new freedom can be used to overcome technical and other limits on component choice. This article then derives the optimum value of the detector collimation for PDs and discloses a previously unrecognised trade-off in PD design. This collection of new results on PD design may later lead to a true full analytic optimisation of PDs. While this article addresses neutron diffractometers, the results should also apply to modest resolution PDs using other radiation including X-rays. Some of its results have strong implications for all instruments using monochromators.

  10. Better powder diffractometers-choice of beam elements and trade-offs in design

    International Nuclear Information System (INIS)

    This article re-examines the equations governing resolution on constant wavelength neutron powder diffractometers (PDs) as cast for Gaussian elements. There is a widely accepted choice of collimators and monochromator mosaic to maximise peak intensity for a given resolution on high-resolution PDs. A second distinct 'optimisation' was found more recently by an acceptance diagram study. This article shows that these 'optimisations' are only two of an infinite number of equivalent element choices. A procedure to find these equivalent configurations is given. This new freedom can be used to overcome technical and other limits on component choice. This article then derives the optimum value of the detector collimation for PDs and discloses a previously unrecognised trade-off in PD design. This collection of new results on PD design may later lead to a true full analytic optimisation of PDs. While this article addresses neutron diffractometers, the results should also apply to modest resolution PDs using other radiation including X-rays. Some of its results have strong implications for all instruments using monochromators

  11. Safe vs. Fair: A Formidable Trade-off in Tackling Climate Change

    Directory of Open Access Journals (Sweden)

    Robert Socolow

    2012-02-01

    Full Text Available Global warming requires a response characterized by forward-looking management of atmospheric carbon and respect for ethical principles. Both safety and fairness must be pursued, and there are severe trade-offs as these are intertwined by the limited headroom for additional atmospheric CO2 emissions. This paper provides a simple numerical mapping at the aggregated level of developed vs. developing countries in which safety and fairness are formulated in terms of cumulative emissions and cumulative per capita emissions respectively. It becomes evident that safety and fairness cannot be achieved simultaneously for strict definitions of both. The paper further posits potential global trading in future cumulative emissions budgets in a world where financial transactions compensate for physical emissions: the safe vs. fair tradeoff is less severe but remains formidable. Finally, we explore very large deployment of engineered carbon sinks and show that roughly 1,000 Gt CO2 of cumulative negative emissions over the century are required to have a significant effect, a remarkable scale of deployment. We also identify the unexplored issue of how such sinks might be treated in sub-global carbon accounting.

  12. Plasticity of hatching in amphibians: evolution, trade-offs, cues and mechanisms.

    Science.gov (United States)

    Warkentin, Karen M

    2011-07-01

    Many species of frogs and salamanders, in at least 12 families, alter their timing of hatching in response to conditions affecting mortality of eggs or larvae. Some terrestrially laid or stranded embryos wait to hatch until they are submerged in water. Some embryos laid above water accelerate hatching if the eggs are dehydrating; others hatch early if flooded. Embryos can hatch early in response to predators and pathogens of eggs or delay hatching in response to predators of larvae; some species do both. The phylogenetic pattern of environmentally cued hatching suggests that similar responses have evolved convergently in multiple amphibian lineages. The use of similar cues, including hypoxia and physical disturbance, in multiple contexts suggests potential shared mechanisms underlying the capacity of embryos to respond to environmental conditions. Shifts in the timing of hatching often have clear benefits, but we know less about the trade-offs that favor plasticity, the mechanisms that enable it, and its evolutionary history. Some potentially important types of cued hatching, such as those involving embryo-parent interactions, are relatively unexplored. I discuss promising directions for research and the opportunities that the hatching of amphibians offers for integrative studies of the mechanisms, ecology and evolution of a critical transition between life-history stages.

  13. Allelic heterogeneity and trade-off shape natural variation for response to soil micronutrient.

    Directory of Open Access Journals (Sweden)

    Seifollah Poormohammad Kiani

    Full Text Available As sessile organisms, plants have to cope with diverse environmental constraints that may vary through time and space, eventually leading to changes in the phenotype of populations through fixation of adaptive genetic variation. To fully comprehend the mechanisms of evolution and make sense of the extensive genotypic diversity currently revealed by new sequencing technologies, we are challenged with identifying the molecular basis of such adaptive variation. Here, we have identified a new variant of a molybdenum (Mo transporter, MOT1, which is causal for fitness changes under artificial conditions of both Mo-deficiency and Mo-toxicity and in which allelic variation among West-Asian populations is strictly correlated with the concentration of available Mo in native soils. In addition, this association is accompanied at different scales with patterns of polymorphisms that are not consistent with neutral evolution and show signs of diversifying selection. Resolving such a case of allelic heterogeneity helps explain species-wide phenotypic variation for Mo homeostasis and potentially reveals trade-off effects, a finding still rarely linked to fitness.

  14. Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.

    Science.gov (United States)

    Mikonranta, Lauri; Friman, Ville-Petri; Laakso, Jouni

    2012-01-01

    Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a result, opportunistic pathogens are likely to experience conflicting selection pressures across different environments, and this could affect their virulence through life-history trait correlations. We studied these correlations experimentally by exposing an opportunistic bacterial pathogen Serratia marcescens to its natural protist predator Tetrahymena thermophila for 13 weeks, after which we measured changes in bacterial traits related to both anti-predator defence and virulence. We found that anti-predator adaptation (producing predator-resistant biofilm) caused a correlative attenuation in virulence. Even though the direct mechanism was not found, reduction in virulence was most clearly connected to a predator-driven loss of a red bacterial pigment, prodigiosin. Moreover, life-history trait evolution was more divergent among replicate populations in the absence of predation, leading also to lowered virulence in some of the 'predator absent' selection lines. Together these findings suggest that the virulence of non-obligatory, opportunistic bacterial pathogens can decrease in environmental reservoirs through life history trade-offs, or random accumulation of mutations that impair virulence traits under relaxed selection.

  15. Genetic dissection of grain size and grain number trade-offs in CIMMYT wheat germplasm.

    Directory of Open Access Journals (Sweden)

    Simon Griffiths

    Full Text Available Grain weight (GW and number per unit area of land (GN are the primary components of grain yield in wheat. In segregating populations both yield components often show a negative correlation among themselves. Here we use a recombinant doubled haploid population of 105 individuals developed from the CIMMYT varieties Weebill and Bacanora to understand the relative contribution of these components to grain yield and their interaction with each other. Weebill was chosen for its high GW and Bacanora for high GN. The population was phenotyped in Mexico, Argentina, Chile and the UK. Two loci influencing grain yield were indicated on 1B and 7B after QTL analysis. Weebill contributed the increasing alleles. The 1B effect, which is probably caused by to the 1BL.1RS rye introgression in Bacanora, was a result of increased GN, whereas, the 7B QTL controls GW. We concluded that increased in GW from Weebill 7B allele is not accompanied by a significant reduction in grain number. The extent of the GW and GN trade-off is reduced. This makes this locus an attractive target for marker assisted selection to develop high yielding bold grain varieties like Weebill. AMMI analysis was used to show that the 7B Weebill allele appears to contribute to yield stability.

  16. Allocation trade-off under climate warming in experimental amphibian populations.

    Science.gov (United States)

    Gao, Xu; Jin, Changnan; Camargo, Arley; Li, Yiming

    2015-01-01

    Climate change could either directly or indirectly cause population declines via altered temperature, rainfall regimes, food availability or phenological responses. However few studies have focused on allocation trade-offs between growth and reproduction under marginal resources, such as food scarce that may be caused by climate warming. Such critical changes may have an unpredicted impact on amphibian life-history parameters and even population dynamics. Here, we report an allocation strategy of adult anuran individuals involving a reproductive stage under experimental warming. Using outdoor mesocosm experiments we simulated a warming scenario likely to occur at the end of this century. We examined the effects of temperature (ambient vs. pre-/post-hibernation warming) and food availability (normal vs. low) on reproduction and growth parameters of pond frogs (Pelophylax nigromaculatus). We found that temperature was the major factor influencing reproductive time of female pond frogs, which showed a significant advancing under post-hibernation warming treatment. While feeding rate was the major factor influencing reproductive status of females, clutch size, and variation of body size for females, showed significant positive correlations between feeding rate and reproductive status, clutch size, or variation of body size. Our results suggested that reproduction and body size of amphibians might be modulated by climate warming or food availability variation. We believe this study provides some new evidence on allocation strategies suggesting that amphibians could adjust their reproductive output to cope with climate warming.

  17. Spatially and Temporally Resolved Analysis of Environmental Trade-Offs in Electricity Generation.

    Science.gov (United States)

    Peer, Rebecca A M; Garrison, Jared B; Timms, Craig P; Sanders, Kelly T

    2016-04-19

    The US power sector is a leading contributor of emissions that affect air quality and climate. It also requires a lot of water for cooling thermoelectric power plants. Although these impacts affect ecosystems and human health unevenly in space and time, there has been very little quantification of these environmental trade-offs on decision-relevant scales. This work quantifies hourly water consumption, emissions (i.e., carbon dioxide, nitrogen oxides, and sulfur oxides), and marginal heat rates for 252 electricity generating units (EGUs) in the Electric Reliability Council of Texas (ERCOT) region in 2011 using a unit commitment and dispatch model (UC&D). Annual, seasonal, and daily variations, as well as spatial variability are assessed. When normalized over the grid, hourly average emissions and water consumption intensities (i.e., output per MWh) are found to be highest when electricity demand is the lowest, as baseload EGUs tend to be the most water and emissions intensive. Results suggest that a large fraction of emissions and water consumption are caused by a small number of power plants, mainly baseload coal-fired generators. Replacing 8-10 existing power plants with modern natural gas combined cycle units would result in reductions of 19-29%, 51-55%, 60-62%, and 13-27% in CO2 emissions, NOx emissions, SOx emissions, and water consumption, respectively, across the ERCOT region for two different conversion scenarios. PMID:26967826

  18. The Lotka-Volterra predator-prey model with foraging-predation risk trade-offs.

    Science.gov (United States)

    Krivan, Vlastimil

    2007-11-01

    This article studies the effects of adaptive changes in predator and/or prey activities on the Lotka-Volterra predator-prey population dynamics. The model assumes the classical foraging-predation risk trade-offs: increased activity increases population growth rate, but it also increases mortality rate. The model considers three scenarios: prey only are adaptive, predators only are adaptive, and both species are adaptive. Under all these scenarios, the neutral stability of the classical Lotka-Volterra model is partially lost because the amplitude of maximum oscillation in species numbers is bounded, and the bound is independent of the initial population numbers. Moreover, if both prey and predators behave adaptively, the neutral stability can be completely lost, and a globally stable equilibrium would appear. This is because prey and/or predator switching leads to a piecewise constant prey (predator) isocline with a vertical (horizontal) part that limits the amplitude of oscillations in prey and predator numbers, exactly as suggested by Rosenzweig and MacArthur in their seminal work on graphical stability analysis of predator-prey systems. Prey and predator activities in a long-term run are calculated explicitly. This article shows that predictions based on short-term behavioral experiments may not correspond to long-term predictions when population dynamics are considered.

  19. Spatial Trade-Offs between Wind Power Production and Bird Collision Avoidance in Agricultural Landscapes

    Directory of Open Access Journals (Sweden)

    Martin Drechsler

    2010-06-01

    Full Text Available The expansion of renewable energy production is seen as an appropriate way to mitigate climate change. Renewable energies are not free of negative external effects on humans and the natural environment. We analyzed the conflict between wind power production and bird protection through the example of one of the most sensitive species, the red kite (Milvus milvus in West Saxony, Germany. We investigated a large number of potential land use scenarios, defined by whether or not each potential site contained a wind turbine (WT. Based on meteorological and ornithological data, we evaluated the land use scenarios for their annual energy supply and impact on the red kite. We identified the efficient land use scenarios that maximized energy supply for a given ecological impact. Within the scope of our analysis, the current allocation of WTs in the study region was considered inefficient. The set of efficient scenarios allowed us to draw conclusions on the trade-offs involved. We developed an indicator that measures the severity of the conflict between wind power production and bird protection. Increasing the minimum distance of WTs to settlements beyond the legal requirements in order to minimize the impact on humans further intensifies the conflict. Our results can support planning authorities in their development of long-term regional plans by identifying areas that are most suitable for wind power production from an integrated point of view.

  20. Risk trade-offs in fish consumption: a public health perspective.

    Science.gov (United States)

    Rheinberger, Christoph M; Hammitt, James K

    2012-11-20

    Fish consumption advisories instruct vulnerable consumers to avoid high mercury fish and to limit total fish intake to reduce neurotoxic risk. Consumption data from the U.S. suggest that nontarget consumers also respond to such advice. These consumers reduce exposure to mercury and other toxicants at the cost of reduction in cardioprotective fatty acids. We present a probabilistic model to assess these risk trade-offs. We use NHANES consumption data to simulate exposure to contaminants and nutrients in fish, employ dose-response relationships to convert exposure to health end points, and monetize them using benefit transfer. Our results suggest that newborns gained on average 0.033 IQ points from their mothers' compliance with the prominent FDA/EPA advisory. The welfare gain for a birth cohort is estimated at $386 million. This gain could be fully offset by increments in cardiovascular risk if 0.6% of consumers aged 40 and older reduced fish intake by one monthly meal until they reached the age of 60 or if 0.1% of them permanently reduced fish intake.

  1. Overview of homogeneous versus heterogeneous core configuration trade-off studies

    International Nuclear Information System (INIS)

    The most significant development in core design trend in the U.S. LMFBR program has been the increased attention given to the heterogeneous core design concept. In recent years, numerous core configuration trade-off studies have been carried out to quantify advantages and disadvantages of the heterogeneous concept relative to the homogeneous concept, and a consensus is emerging among the U.S. core designers. It appears that the technical and economic performance differences between homogeneous and heterogeneous core designs are very small; however, the heterogeneous concept provides a definite safety/licensing advantage. he technical and economic performance comparison between homogeneous and heterogeneous core configurations is difficult to quantify. In fact, in most cases, the perceived advantages and/or disadvantages are dictated by the consistency in the comparison (optimized for one concept versus non-optimized for the other, etc.) rather than by any inherent differences. Some of the technical and economic issues relevant to the homogeneous versus heterogeneous comparison are summarized

  2. Variation in ovule and seed size and associated size-number trade-offs in angiosperms.

    Science.gov (United States)

    Greenway, Carly A; Harder, Lawrence D

    2007-05-01

    Unlike pollen and seed size, the extent and causes of variation in ovule size remain unexplored. Based on 45 angiosperm species, we assessed whether intra- and interspecific variation in ovule size is consistent with cost minimization during ovule production or allows maternal plants to dominate conflict with their seeds concerning resource investment. Despite considerable intraspecific variation in ovule volume (mean CV = 0.356), ovule production by few species was subject to a size-number trade-off. Among the sampled species, ovule volume varied two orders of magnitude, whereas seed volume varied four orders of magnitude. Ovule volume varied positively among species with flower mass and negatively with ovule number. Tenuinucellate ovules were generally larger that crassinucellate ovules, and species with apical placentation (which mostly have uniovulate ovaries) had smaller ovules than those with other placentation types. Seed volume varied positively among species with fruit mass and seed development time, but negatively with seed number. Seeds grew a median 93-fold larger than the ovules from which they originated. Our results provide equivocal evidence that selection minimizes ovule size to allow efficient resource allocation after fertilization, but stronger evidence that ovule size affords maternal plants an advantage in parent-offspring conflict. PMID:21636453

  3. Primates' behavioural responses to tourists: evidence for a trade-off between potential risks and benefits.

    Science.gov (United States)

    Maréchal, Laëtitia; MacLarnon, Ann; Majolo, Bonaventura; Semple, Stuart

    2016-01-01

    The presence of, and interactions with tourists can be both risky and beneficial for wild animals. In wildlife tourism settings, animals often experience elevated rates of aggression from conspecifics, and they may also be threatened or physically aggressed by the tourists themselves. However, tourist provisioning of wild animals provides them with highly desirable foods. In situations of conflicting motivations such as this, animals would be expected to respond using behavioural coping mechanisms. In the present study, we investigated how animals respond to tourist pressure, using wild adult Barbary macaques in the Middle Atlas Mountains, Morocco, as a case study. We found evidence that these animals use a range of different behavioural coping mechanisms-physical avoidance, social support, affiliative, aggressive and displacement behaviours-to cope with the stress associated with tourists. The pattern of use of such behaviours appears to depend on a trade-off between perceived risks and potential benefits. We propose a framework to describe how animals respond to conflicting motivational situations, such as the presence of tourists, that present simultaneously risks and benefits. PMID:27628213

  4. Allocation trade-off under climate warming in experimental amphibian populations

    Science.gov (United States)

    Gao, Xu; Jin, Changnan; Camargo, Arley

    2015-01-01

    Climate change could either directly or indirectly cause population declines via altered temperature, rainfall regimes, food availability or phenological responses. However few studies have focused on allocation trade-offs between growth and reproduction under marginal resources, such as food scarce that may be caused by climate warming. Such critical changes may have an unpredicted impact on amphibian life-history parameters and even population dynamics. Here, we report an allocation strategy of adult anuran individuals involving a reproductive stage under experimental warming. Using outdoor mesocosm experiments we simulated a warming scenario likely to occur at the end of this century. We examined the effects of temperature (ambient vs. pre-/post-hibernation warming) and food availability (normal vs. low) on reproduction and growth parameters of pond frogs (Pelophylax nigromaculatus). We found that temperature was the major factor influencing reproductive time of female pond frogs, which showed a significant advancing under post-hibernation warming treatment. While feeding rate was the major factor influencing reproductive status of females, clutch size, and variation of body size for females, showed significant positive correlations between feeding rate and reproductive status, clutch size, or variation of body size. Our results suggested that reproduction and body size of amphibians might be modulated by climate warming or food availability variation. We believe this study provides some new evidence on allocation strategies suggesting that amphibians could adjust their reproductive output to cope with climate warming. PMID:26500832

  5. On the Throughput-Delay Trade-off in Georouting Networks

    CERN Document Server

    Jacquet, Philippe; Mans, Bernard; Silva, Alonso

    2011-01-01

    We study the scaling properties of a georouting scheme in a wireless multi-hop network of $n$ mobile nodes. Our aim is to increase the network capacity quasi linearly with $n$ while keeping the average delay bounded. In our model, mobile nodes move according to an i.i.d. random walk with velocity $v$ and transmit packets to randomly chosen destinations. The average packet delivery delay of our scheme is of order $1/v$ and it achieves the network capacity of order $\\frac{n}{\\log n\\log\\log n}$. This shows a practical throughput-delay trade-off, in particular when compared with the seminal result of Gupta and Kumar which shows network capacity of order $\\sqrt{n/\\log n}$ and negligible delay and the groundbreaking result of Grossglausser and Tse which achieves network capacity of order $n$ but with an average delay of order $\\sqrt{n}/v$. We confirm the generality of our analytical results using simulations under various interference models.

  6. Life history trade-offs and relaxed selection can decrease bacterial virulence in environmental reservoirs.

    Directory of Open Access Journals (Sweden)

    Lauri Mikonranta

    Full Text Available Pathogen virulence is usually thought to evolve in reciprocal selection with the host. While this might be true for obligate pathogens, the life histories of opportunistic pathogens typically alternate between within-host and outside-host environments during the infection-transmission cycle. As a result, opportunistic pathogens are likely to experience conflicting selection pressures across different environments, and this could affect their virulence through life-history trait correlations. We studied these correlations experimentally by exposing an opportunistic bacterial pathogen Serratia marcescens to its natural protist predator Tetrahymena thermophila for 13 weeks, after which we measured changes in bacterial traits related to both anti-predator defence and virulence. We found that anti-predator adaptation (producing predator-resistant biofilm caused a correlative attenuation in virulence. Even though the direct mechanism was not found, reduction in virulence was most clearly connected to a predator-driven loss of a red bacterial pigment, prodigiosin. Moreover, life-history trait evolution was more divergent among replicate populations in the absence of predation, leading also to lowered virulence in some of the 'predator absent' selection lines. Together these findings suggest that the virulence of non-obligatory, opportunistic bacterial pathogens can decrease in environmental reservoirs through life history trade-offs, or random accumulation of mutations that impair virulence traits under relaxed selection.

  7. Assessing the Climate Trade-Offs of Gasoline Direct Injection Engines.

    Science.gov (United States)

    Zimmerman, Naomi; Wang, Jonathan M; Jeong, Cheol-Heon; Wallace, James S; Evans, Greg J

    2016-08-01

    Compared to port fuel injection (PFI) engine exhaust, gasoline direct injection (GDI) engine exhaust has higher emissions of black carbon (BC), a climate-warming pollutant. However, the relative increase in BC emissions and climate trade-offs of replacing PFI vehicles with more fuel efficient GDI vehicles remain uncertain. In this study, BC emissions from GDI and PFI vehicles were compiled and BC emissions scenarios were developed to evaluate the climate impact of GDI vehicles using global warming potential (GWP) and global temperature potential (GTP) metrics. From a 20 year time horizon GWP analysis, average fuel economy improvements ranging from 0.14 to 14% with GDI vehicles are required to offset BC-induced warming. For all but the lowest BC scenario, installing a gasoline particulate filter with an 80% BC removal efficiency and engine operation, and fuel composition. More work is needed to understand BC formation mechanisms in GDI engines to ensure that the climate impacts of this engine technology are minimal.

  8. Mapping visual analogue scale health state valuations onto standard gamble and time trade-off values.

    Science.gov (United States)

    Dolan, P; Sutton, M

    1997-05-01

    Despite becoming increasingly common in evaluations of health care, different methods of quantitatively measuring health status appear to produce different valuations for identical descriptions of health. This paper reports on a study that elicited health state valuations from the general public using three different methods: the visual analogue scale (VAS), the standard gamble (SG) and the time trade-off (TTO). Two variants of the SG and TTO were tested: Props (using specially designed boards and cards); and No Props (using a self-completion booklet). This paper focuses on empirical relationships between health state valuations from the VAS and the (four) other methods. The relationships were estimated using Tobit regression of individual-level data. In contrast to a priori expectations, the mapping functions estimated suggest that differences are more pronounced across variant than across method. Furthermore, relationships with VAS scores are found to depend on the severity of the state: TTO Props valuations are higher than VAS responses for mild states and lower for more severe states; SG Props valuations are broadly similar to VAS scores over a wide range; and No Props responses are consistently higher than VAS valuations, particularly for more severe states. Explanations are proposed for these findings. PMID:9160441

  9. Trade-offs between biodiversity conservation and economic development in five tropical forest landscapes.

    Science.gov (United States)

    Sandker, Marieke; Ruiz-Perez, Manuel; Campbell, Bruce M

    2012-10-01

    This study explores how conservation and development are interlinked and quantifies their reciprocal trade-offs. It identifies interventions which hold a promise to improve both conservation and development outcomes. The study finds that development trajectories can either be at the cost of conservation or can benefit conservation, but in all cases sustained poverty negatively affects conservation in the long term. Most scenarios with better outcomes for conservation come at a cost for development and the financial benefits of payments for environmental services (PES) are not sufficient to compensate for lost opportunities to earn cash. However, implementation of strategies for reducing emissions from deforestation and forest degradation in locations with low population densities come close to overcoming opportunity costs. Environmental services and subsistence income enhance the attractiveness of conservation scenarios to local people and in situations where these benefits are obvious, PES may provide the extra cash incentive to tip the balance in favor of such a scenario. The paper stresses the importance of external factors (such as industrial investments and the development of the national economy) in determining landscape scale outcomes, and suggests a negotiating and visioning role for conservation agencies.

  10. Trade-off between cellular immunity and life span in mealworm beetles Tenebrio molitor

    Institute of Scientific and Technical Information of China (English)

    Indrikis KRAMS; Jan(i)na DAUK(S)TE; Inese KIVLENIECE; Ants KAASIK; Tatjana KRAMA; Todd M.FREEBERG; Markus J.RANTALA

    2013-01-01

    Encapsulation is a nonspecific,cellular response through which insects defend themselves against multicellular pathogens.During this immune reaction,haemocytes recognize an object as foreign and cause other haemocytes to aggregate and form a capsule around the object,often consisting of melanized cells.The process of melanisation is accompanied by the formation of potentially toxic reactive oxygen species,which can kill not only pathogens but also host cells.In this study we tested whether the encapsulation response is costly in mealworm beetles Tenebrio molitor.We found a negative relationship between the duration of implantation via a nylon monofilament and remaining life span.We also found a negative relationship between the strength of immune response and remaining life span,suggesting that cellular immunity is costly in T.molitor,and that there is a trade-off between immune response and remaining life span.However,this relationship disappeared at 31-32 hours of implantation at 25 ± 2℃.As the disappearance of a relationship between duration of implantation and lifespan coincided with the highest values of encapsulation response,we concluded that the beetles stopped investment in the production of melanotic cells,as the implant,a synthetic parasite,was fully isolated from the host's tissues.

  11. Valuation of environmental and societal trade-offs of renewable energy sources

    International Nuclear Information System (INIS)

    Use of renewable energy sources is one solution to decrease green house gas emissions and the use of polluting fossil fuels. Renewables differ in their environmental and societal impacts, and to design sound renewable energy policy, societies need to assess the trade-offs between alternative sources. To enable the evaluation and comparison of renewable energy production alternatives in Finland, this paper applies the choice experiment to elicit the monetary information on people's preferences for four renewable energy sources: wind power, hydro power and energy from crops and wood, and considers four impacts of energy production: effects on biodiversity, local jobs, carbon emissions and household's electricity bill. The nested logit analysis reveals that higher income, male gender, young age, and pro-environmental attitude increase the probability to choose renewable energy instead of the current energy mix. Wind power is, on average, the most popular renewable energy technology, but regional differences exist. Biodiversity deterioration should be avoided. The national aggregate willingness to pay, based on stated preferences rather than preferences revealed by actual market behavior, for a combination of renewable energy technologies that corresponds to Finland's climate change and energy policy is over 500 million Euros. - Highlights: • Preferences for renewable energy sources are elicited with choice experiment. • Wind power is the most popular source in general. • Regional differences exist: energy from wood is favored in rural areas. • Biodiversity deterioration should be avoided

  12. Plant responses, climate pivot points, and trade-offs in water-limited ecosystems

    Science.gov (United States)

    Munson, Seth M.

    2013-01-01

    Plant species in dryland ecosystems are limited by water availability and may be vulnerable to increases in aridity. Methods are needed to monitor and assess the rate of change in plant abundance and composition in relation to climate, understand the potential for degradation in dryland ecosystems, and forecast future changes in plant species assemblages. I employ nearly a century of vegetation monitoring data from three North American deserts to demonstrate an approach to determine plant species responses to climate and critical points over a range of climatic conditions at which plant species shift from increases to decreases in abundance (climate pivot points). I assess these metrics from a site to regional scale and highlight how these indicators of plant performance can be modified by the physical and biotic environment. For example, shrubs were more responsive to drought and high temperatures on shallow soils with limited capacity to store water and fine-textured soils with slow percolation rates, whereas perennial grasses were more responsive to precipitation in sparse shrublands than in relatively dense grasslands and shrublands, where competition for water is likely more intense. The responses and associated climate pivot points of plant species aligned with their lifespan and structural characteristics, and the relationship between responses and climate pivot points provides evidence of the trade-off between the capacity of a plant species to increase in abundance when water is available and its drought resistance.

  13. Reproductive trade-offs in extant hunter-gatherers suggest adaptive mechanism for the Neolithic expansion.

    Science.gov (United States)

    Page, Abigail E; Viguier, Sylvain; Dyble, Mark; Smith, Daniel; Chaudhary, Nikhil; Salali, Gul Deniz; Thompson, James; Vinicius, Lucio; Mace, Ruth; Migliano, Andrea Bamberg

    2016-04-26

    The Neolithic demographic transition remains a paradox, because it is associated with both higher rates of population growth and increased morbidity and mortality rates. Here we reconcile the conflicting evidence by proposing that the spread of agriculture involved a life history quality-quantity trade-off whereby mothers traded offspring survival for increased fertility, achieving greater reproductive success despite deteriorating health. We test this hypothesis by investigating fertility, mortality, health, and overall reproductive success in Agta hunter-gatherers whose camps exhibit variable levels of sedentarization, mobility, and involvement in agricultural activities. We conducted blood composition tests in 345 Agta and found that viral and helminthic infections as well as child mortality rates were significantly increased with sedentarization. Nonetheless, both age-controlled fertility and overall reproductive success were positively affected by sedentarization and participation in cultivation. Thus, we provide the first empirical evidence, to our knowledge, of an adaptive mechanism in foragers that reconciles the decline in health and child survival with the observed demographic expansion during the Neolithic. PMID:27071109

  14. Primates’ behavioural responses to tourists: evidence for a trade-off between potential risks and benefits

    Science.gov (United States)

    Maréchal, Laëtitia; MacLarnon, Ann; Majolo, Bonaventura; Semple, Stuart

    2016-01-01

    The presence of, and interactions with tourists can be both risky and beneficial for wild animals. In wildlife tourism settings, animals often experience elevated rates of aggression from conspecifics, and they may also be threatened or physically aggressed by the tourists themselves. However, tourist provisioning of wild animals provides them with highly desirable foods. In situations of conflicting motivations such as this, animals would be expected to respond using behavioural coping mechanisms. In the present study, we investigated how animals respond to tourist pressure, using wild adult Barbary macaques in the Middle Atlas Mountains, Morocco, as a case study. We found evidence that these animals use a range of different behavioural coping mechanisms–physical avoidance, social support, affiliative, aggressive and displacement behaviours–to cope with the stress associated with tourists. The pattern of use of such behaviours appears to depend on a trade-off between perceived risks and potential benefits. We propose a framework to describe how animals respond to conflicting motivational situations, such as the presence of tourists, that present simultaneously risks and benefits. PMID:27628213

  15. 85Kr management trade-offs: a perspective to total radiation dose commitment

    International Nuclear Information System (INIS)

    Radiological consequences arising from the trade-offs for 85Kr waste management from possible nuclear fuel resource recovery activities have been investigated. The reference management technique is to release all the waste gas to the atmosphere where it is diluted and dispersed. A potential alternative is to collect, concentrate, package and submit the gas to long-term storage. This study compares the radiation dose commitment to the public and to the occupationally exposed work force from these alternatives. The results indicate that it makes little difference to the magnitude of the world population dose whether 85Kr is captured and stored or chronically released to the environment. Further, comparisons of radiation exposures (for the purpose of estimating health effects) at very low dose rates to very large populations with exposures to a small number of occupationally exposed workers who each receive much higher dose rates may be misleading. Finally, cost studies (EPA 1976 and DOE 1979a) show that inordinate amounts of money will be required to lower this already extremely small 80-year cumulative world population dose of 0.05 mrem/person

  16. Addressing Trade-offs: Experiences from Conservation and Development Initiatives in the Mkuze Wetlands, South Africa

    Directory of Open Access Journals (Sweden)

    Catie Burlando

    2009-12-01

    Full Text Available Present-day conservation policies generally include the aim to integrate biodiversity conservation and local development, and describe this as a win–win solution that can satisfy all interests. This is challenged by research claiming that many efforts fail to match practice to rhetoric. South Africa has made strong commitments to fulfill the dual goals of conservation and development, and the iSimangaliso Wetland Park is promoted as an example of this. We explore present and potential outcomes of conservation and development interventions in a community bordering the Wetland Park through the perspective of different stakeholders, with the aim of uncovering opportunities and risks. In terms of improving local livelihoods as well as involvement in conservation, the success of the studied interventions varied. Local communities may accept restrictions on resource use as a result of realistic and fairly negotiated trade-offs, but if perceived as unjust and imposed from above, then mistrust and resistance will increase. In this area, collaboration between conservation organizations and the local community had improved, but still faced problems associated with unequal power relations, unrealistic expectations, and a lack of trust, transparency, and communication. As unsustainable efforts are a waste of funds and engagement, and may even become counterproductive, policy visions need to be matched by realistic allocations of staff, time, funds, and training. At the national and international level, the true cost of conservation has to be recognized and budgeted for if efforts at integrating conservation and development are to succeed.

  17. Publish or Patent: Bibliometric evidence for empirical trade-offs in national funding strategies

    CERN Document Server

    Shelton, Robert D

    2011-01-01

    Multivariate linear regression models suggest a trade-off in allocations of national R&D investments. Government funding, and spending in the higher education sector, seem to encourage publications, whereas other components such as industrial funding, and spending in the business sector, encourage patenting. Our results help explain why the US trails the EU in publications, because of its focus on industrial funding - some 70% of its total R&D investment. Conversely, it also helps explain why the EU trails the US in patenting. Government funding is indicated as a negative incentive to high-quality patenting. The models here can also be used to predict an output indicator for a country, once the appropriate input indicator is known. This usually is done within a dataset for a single year, but the process can be extended to predict outputs a few years into the future, if reasonable forecasts can be made of the input indicators. We provide new forecasts about the further relationships of the US, the EU-2...

  18. Allocation trade-off under climate warming in experimental amphibian populations.

    Science.gov (United States)

    Gao, Xu; Jin, Changnan; Camargo, Arley; Li, Yiming

    2015-01-01

    Climate change could either directly or indirectly cause population declines via altered temperature, rainfall regimes, food availability or phenological responses. However few studies have focused on allocation trade-offs between growth and reproduction under marginal resources, such as food scarce that may be caused by climate warming. Such critical changes may have an unpredicted impact on amphibian life-history parameters and even population dynamics. Here, we report an allocation strategy of adult anuran individuals involving a reproductive stage under experimental warming. Using outdoor mesocosm experiments we simulated a warming scenario likely to occur at the end of this century. We examined the effects of temperature (ambient vs. pre-/post-hibernation warming) and food availability (normal vs. low) on reproduction and growth parameters of pond frogs (Pelophylax nigromaculatus). We found that temperature was the major factor influencing reproductive time of female pond frogs, which showed a significant advancing under post-hibernation warming treatment. While feeding rate was the major factor influencing reproductive status of females, clutch size, and variation of body size for females, showed significant positive correlations between feeding rate and reproductive status, clutch size, or variation of body size. Our results suggested that reproduction and body size of amphibians might be modulated by climate warming or food availability variation. We believe this study provides some new evidence on allocation strategies suggesting that amphibians could adjust their reproductive output to cope with climate warming. PMID:26500832

  19. Cost-benefit trade-offs of bird activity in apple orchards.

    Science.gov (United States)

    Peisley, Rebecca K; Saunders, Manu E; Luck, Gary W

    2016-01-01

    Birds active in apple orchards in south-eastern Australia can contribute positively (e.g., control crop pests) or negatively (e.g., crop damage) to crop yields. Our study is the first to identify net outcomes of these activities, using six apple orchards, varying in management intensity, in south-eastern Australia as a study system. We also conducted a predation experiment using real and artificial codling moth (Cydia pomonella) larvae (a major pest in apple crops). We found that: (1) excluding birds from branches of apple trees resulted in an average of 12.8% more apples damaged by insects; (2) bird damage to apples was low (1.9% of apples); and (3) when trading off the potential benefits (biological control) with costs (bird damage to apples), birds provided an overall net benefit to orchard growers. We found that predation of real codling moth larvae was higher than for plasticine larvae, suggesting that plasticine prey models are not useful for inferring actual predation levels. Our study shows how complex ecological interactions between birds and invertebrates affect crop yield in apples, and provides practical strategies for improving the sustainability of orchard systems. PMID:27413639

  20. Multi-objective evolutionary algorithm for investigating the trade-off between pleiotropy and redundancy

    Science.gov (United States)

    Ong, Zhiyang; Lo, Andy Hao-Wei; Berryman, Matthew; Abbott, Derek

    2005-12-01

    The trade-off between pleiotropy and redundancy in telecommunications networks is analyzed in this paper. They are optimized to reduce installation costs and propagation delays. Pleiotropy of a server in a telecommunications network is defined as the number of clients and servers that it can service whilst redundancy is described as the number of servers servicing a client. Telecommunications networks containing many servers with large pleiotropy are cost-effective but vulnerable to network failures and attacks. Conversely, those networks containing many servers with high redundancy are reliable but costly. Several key issues regarding the choice of cost functions and techniques in evolutionary computation (such as the modeling of Darwinian evolution, and mutualism and commensalism) will be discussed, and a future research agenda is outlined. Experimental results indicate that the pleiotropy of servers in the optimum network does improve, whilst the redundancy of clients do not vary significantly, as expected, with evolving networks. This is due to the controlled evolution of networks that is modeled by the steady-state genetic algorithm; changes in telecommunications networks that occur drastically over a very short period of time are rare.

  1. The effects of trauma exposure and posttraumatic stress disorder (PTSD on the emotion-induced memory trade-off

    Directory of Open Access Journals (Sweden)

    Katherine R. Mickley Steinmetz

    2012-06-01

    Full Text Available Many studies of memory changes in individuals with PTSD have focused on memory for trauma. However, it is unclear if these mnemonic differences extend beyond trauma memory to memory for other positive and negative information and if they are specific to individuals with PTSD or extend to other individuals who have experienced trauma. The present study examined the influences of trauma exposure and PTSD on an effect that may parallel tunnel memory in PTSD: the emotion-induced memory trade-off, whereby emotional aspects of an experience are remembered at the expense of the nonemotional context. Three groups (25 with current PTSD, 27 who had experienced trauma but did not have current PTSD, and 25 controls who had neither experienced significant trauma nor met criteria for current PTSD were shown complex visual scenes that included an item (positive, negative, or neutral placed on a neutral background. 45 minutes later, participants underwent a recognition memory test for the items and backgrounds separately. An emotion-induced memory trade-off was said to occur when there was a significant difference in item and background memory for emotional scenes, but not for neutral scenes. People with PTSD, like the other groups, were more likely to remember positive and negative items than neutral items. People with PTSD exhibited a memory trade-off, but this trade-off was no larger than for the non-trauma control group. Trauma-exposed people without a current diagnosis of PTSD did not show a trade-off, because they remembered the items within scenes better than their contexts even for neutral scenes. These results suggest that i the effect of emotion on memory for visual scenes is similar in people with PTSD and control participants, and ii people who have experienced trauma, but do not have PTSD, may have a different way of attending to and remembering visual scenes, exhibiting less of a memory trade-off than either control participants or people with

  2. 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...

  3. Estimation and detection information trade-off for x-ray system optimization

    Science.gov (United States)

    Cushing, Johnathan B.; Clarkson, Eric W.; Mandava, Sagar; Bilgin, Ali

    2016-05-01

    X-ray Computed Tomography (CT) systems perform complex imaging tasks to detect and estimate system parameters, such as a baggage imaging system performing threat detection and generating reconstructions. This leads to a desire to optimize both the detection and estimation performance of a system, but most metrics only focus on one of these aspects. When making design choices there is a need for a concise metric which considers both detection and estimation information parameters, and then provides the user with the collection of possible optimal outcomes. In this paper a graphical analysis of Estimation and Detection Information Trade-off (EDIT) will be explored. EDIT produces curves which allow for a decision to be made for system optimization based on design constraints and costs associated with estimation and detection. EDIT analyzes the system in the estimation information and detection information space where the user is free to pick their own method of calculating these measures. The user of EDIT can choose any desired figure of merit for detection information and estimation information then the EDIT curves will provide the collection of optimal outcomes. The paper will first look at two methods of creating EDIT curves. These curves can be calculated using a wide variety of systems and finding the optimal system by maximizing a figure of merit. EDIT could also be found as an upper bound of the information from a collection of system. These two methods allow for the user to choose a method of calculation which best fits the constraints of their actual system.

  4. Trade-offs between wood supply and caribou habitat in northwestern Ontario

    Directory of Open Access Journals (Sweden)

    Daniel McKenney

    1998-03-01

    Full Text Available Woodland caribou habitat management in northwestern Ontario is a complex spatial problem. The Strategic Forest Management Model (SFMM, a linear programming PC-based planning tool being developed in Ontario, was used to examine the impacts of alternative management strategies on caribou habitat. The management alternatives investigated included the cessation of timber management and maximising the present value of wood production without any explicit concern (in the model for caribou. Three major findings are worth noting: 1 trying to maintain prime caribou habitat within active Forest Management Units will come at a cost to wood supply but the cost will depend on the absolute amount of area affected and the spatial configuration of that land in relation to mills. The cost of maintaining caribou habitat in one management unit at a level about 25 000 hectares is roughly $324 000 per year (about 3 cents for each Ontario resident. The imposition of an even-flow constraint on wood production is in fact potentially more costly; 2 Given the region is heavily dominated by spruce aged 90 years and over, forest succession and fire disturbance will likely cause large declines in prime caribou habitat in the near to medium term (20 to 40 years even if no timber harvesting occurs; 3 The complexities of the trade-offs in this resource management problem highlight the limitations of any single modelling tool to satisfactorily address all issues. Planners need to take advantage of a wide range of analytical techniques to quantify the issues and formulate integrated policies.

  5. Environmental and economic trade-offs in a watershed when using corn stover for bioenergy.

    Science.gov (United States)

    Gramig, Benjamin M; Reeling, Carson J; Cibin, Raj; Chaubey, Indrajeet

    2013-02-19

    There is an abundant supply of corn stover in the United States that remains after grain is harvested which could be used to produce cellulosic biofuels mandated by the current Renewable Fuel Standard (RFS). This research integrates the Soil Water Assessment Tool (SWAT) watershed model and the DayCent biogeochemical model to investigate water quality and soil greenhouse gas flux that results when corn stover is collected at two different rates from corn-soybean and continuous corn crop rotations with and without tillage. Multiobjective watershed-scale optimizations are performed for individual pollutant-cost minimization criteria based on the economic cost of each cropping practice and (individually) the effect on nitrate, total phosphorus, sediment, or global warming potential. We compare these results with a purely economic optimization that maximizes stover production at the lowest cost without taking environmental impacts into account. We illustrate trade-offs between cost and different environmental performance criteria, assuming that nutrients contained in any stover collected must be replaced. The key finding is that stover collection using the practices modeled results in increased contributions to atmospheric greenhouse gases while reducing nitrate and total phosphorus loading to the watershed relative to the status quo without stover collection. Stover collection increases sediment loading to waterways relative to when no stover is removed for each crop rotation-tillage practice combination considered; no-till in combination with stover collection reduced sediment loading below baseline conditions without stover collection. Our results suggest that additional information is needed about (i) the level of nutrient replacement required to maintain grain yields and (ii) cost-effective management practices capable of reducing soil erosion when crop residues are removed in order to avoid contributions to climate change and water quality impairments as a result

  6. Trade-Offs between Economic and Environmental Impacts of Introducing Legumes into Cropping Systems

    Science.gov (United States)

    Reckling, Moritz; Bergkvist, Göran; Watson, Christine A.; Stoddard, Frederick L.; Zander, Peter M.; Walker, Robin L.; Pristeri, Aurelio; Toncea, Ion; Bachinger, Johann

    2016-01-01

    Europe's agriculture is highly specialized, dependent on external inputs and responsible for negative environmental impacts. Legume crops are grown on less than 2% of the arable land and more than 70% of the demand for protein feed supplement is imported from overseas. The integration of legumes into cropping systems has the potential to contribute to the transition to a more resource-efficient agriculture and reduce the current protein deficit. Legume crops influence the production of other crops in the rotation making it difficult to evaluate the overall agronomic effects of legumes in cropping systems. A novel assessment framework was developed and applied in five case study regions across Europe with the objective of evaluating trade-offs between economic and environmental effects of integrating legumes into cropping systems. Legumes resulted in positive and negative impacts when integrated into various cropping systems across the case studies. On average, cropping systems with legumes reduced nitrous oxide emissions by 18 and 33% and N fertilizer use by 24 and 38% in arable and forage systems, respectively, compared to systems without legumes. Nitrate leaching was similar with and without legumes in arable systems and reduced by 22% in forage systems. However, grain legumes reduced gross margins in 3 of 5 regions. Forage legumes increased gross margins in 3 of 3 regions. Among the cropping systems with legumes, systems could be identified that had both relatively high economic returns and positive environmental impacts. Thus, increasing the cultivation of legumes could lead to economic competitive cropping systems and positive environmental impacts, but achieving this aim requires the development of novel management strategies informed by the involvement of advisors and farmers. PMID:27242870

  7. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient.

    Science.gov (United States)

    Dostálek, Tomáš; Rokaya, Maan Bahadur; Maršík, Petr; Rezek, Jan; Skuhrovec, Jiří; Pavela, Roman; Münzbergová, Zuzana

    2016-01-01

    The type and intensity of plant-herbivore interactions are likely to be altered under climate change as a consequence of differential dispersal rates of plants and their herbivores. Here, we studied variation in herbivore damage on Salvia nubicola in the field and compared its growth and defence strategies against herbivores in controlled conditions using seeds from populations along a broad altitudinal gradient. Our work is one of the first studies to simultaneously measure complex intraspecific variation in plant growth, direct and indirect defences as well as plant tolerance (ability to regrow) as a consequence of herbivore attack simulated by clipping. In the field, we found that plants experienced higher herbivore pressure in lower altitudes. In the greenhouse, plants grown from seeds collected in lower-altitude populations grew better and produced a higher content of phenolic compounds (direct defence) and volatile organic compounds (indirect defence) in response to simulated herbivory. However, there were no differences in tolerance and effect of S. nubicola extracts on the model generalist herbivore Spodoptera littoralis (direct defence) along the altitudinal gradient. Although we found that S. nubicola developed a range of defence strategies, the strategies do not seem to be used simultaneously in all populations even though most of them are correlated with altitudinal gradient. Our finding is in agreement with the current knowledge that co-expression of multiple defences might be costly for a plant, since investment in defensive traits is assumed to reduce the resource availability for growth and reproduction. Our study thus shows the importance of simultaneous study of different defence strategies since understanding these trade-offs could be necessary for detecting the mechanisms by which plants are able to cope with future climate change. PMID:27169609

  8. Ocean acidification may aggravate social-ecological trade-offs in coastal fisheries.

    Science.gov (United States)

    Voss, Rudi; Quaas, Martin F; Schmidt, Jörn O; Kapaun, Ute

    2015-01-01

    Ocean Acidification (OA) will influence marine ecosystems by changing species abundance and composition. Major effects are described for calcifying organisms, which are significantly impacted by decreasing pH values. Direct effects on commercially important fish are less well studied. The early life stages of fish populations often lack internal regulatory mechanisms to withstand the effects of abnormal pH. Negative effects can be expected on growth, survival, and recruitment success. Here we study Norwegian coastal cod, one of the few stocks where such a negative effect was experimentally quantified, and develop a framework for coupling experimental data on OA effects to ecological-economic fisheries models. In this paper, we scale the observed physiological responses to the population level by using the experimentally determined mortality rates as part of the stock-recruitment relationship. We then use an ecological-economic optimization model, to explore the potential effect of rising CO2 concentration on ecological (stock size), economic (profits), consumer-related (harvest) and social (employment) indicators, with scenarios ranging from present day conditions up to extreme acidification. Under the assumptions of our model, yields and profits could largely be maintained under moderate OA by adapting future fishing mortality (and related effort) to changes owing to altered pH. This adaptation comes at the costs of reduced stock size and employment, however. Explicitly visualizing these ecological, economic and social tradeoffs will help in defining realistic future objectives. Our results can be generalized to any stressor (or stressor combination), which is decreasing recruitment success. The main findings of an aggravation of trade-offs will remain valid. This seems to be of special relevance for coastal stocks with limited options for migration to avoid unfavorable future conditions and subsequently for coastal fisheries, which are often small scale local

  9. Ocean acidification may aggravate social-ecological trade-offs in coastal fisheries.

    Directory of Open Access Journals (Sweden)

    Rudi Voss

    Full Text Available Ocean Acidification (OA will influence marine ecosystems by changing species abundance and composition. Major effects are described for calcifying organisms, which are significantly impacted by decreasing pH values. Direct effects on commercially important fish are less well studied. The early life stages of fish populations often lack internal regulatory mechanisms to withstand the effects of abnormal pH. Negative effects can be expected on growth, survival, and recruitment success. Here we study Norwegian coastal cod, one of the few stocks where such a negative effect was experimentally quantified, and develop a framework for coupling experimental data on OA effects to ecological-economic fisheries models. In this paper, we scale the observed physiological responses to the population level by using the experimentally determined mortality rates as part of the stock-recruitment relationship. We then use an ecological-economic optimization model, to explore the potential effect of rising CO2 concentration on ecological (stock size, economic (profits, consumer-related (harvest and social (employment indicators, with scenarios ranging from present day conditions up to extreme acidification. Under the assumptions of our model, yields and profits could largely be maintained under moderate OA by adapting future fishing mortality (and related effort to changes owing to altered pH. This adaptation comes at the costs of reduced stock size and employment, however. Explicitly visualizing these ecological, economic and social tradeoffs will help in defining realistic future objectives. Our results can be generalized to any stressor (or stressor combination, which is decreasing recruitment success. The main findings of an aggravation of trade-offs will remain valid. This seems to be of special relevance for coastal stocks with limited options for migration to avoid unfavorable future conditions and subsequently for coastal fisheries, which are often small

  10. Reproductive trade-offs may moderate the impact of Gyrodactylus salaris in warmer climates.

    Directory of Open Access Journals (Sweden)

    Scott J Denholm

    Full Text Available Gyrodactylus salaris is a notifiable freshwater ectoparasite of salmonids. Its primary host is Atlantic salmon (Salmo salar, upon which infections can cause death, and have led to massive declines in salmon numbers in Norway, where the parasite is widespread. Different strains of S. salar vary in their susceptibility, with Atlantic strains (such as those found in Norway exhibiting no resistance to the parasite, and Baltic strains demonstrating an innate resistance sufficient to regulate parasite numbers on the host causing it to either die out or persist at a low level. In this study, Leslie matrix and compartmental models were used to generate data that demonstrated the population growth of G. salaris on an individual host is dependent on the total number of offspring per parasite, its longevity and the timing of its births. The data demonstrated that the key factor determining the rate of G. salaris population growth is the time at which the parasite first gives birth, with rapid birth rate giving rise to large population size. Furthermore, it was shown that though the parasite can give birth up to four times, only two births are required for the population to persist as long as the first birth occurs before a parasite is three days old. As temperature is known to influence the timing of the parasite's first birth, greater impact may be predicted if introduced to countries with warmer climates than Norway, such as the UK and Ireland which are currently recognised to be free of G. salaris. However, the outputs from the models developed in this study suggest that temperature induced trade-offs between the total number of offspring the parasite gives birth to and the first birth timing may prevent increased population growth rates over those observed in Norway.

  11. Estimation and detection information trade-off for x-ray system optimization

    Science.gov (United States)

    Cushing, Johnathan B.; Clarkson, Eric W.; Mandava, Sagar; Bilgin, Ali

    2016-05-01

    X-ray Computed Tomography (CT) systems perform complex imaging tasks to detect and estimate system parameters, such as a baggage imaging system performing threat detection and generating reconstructions. This leads to a desire to optimize both the detection and estimation performance of a system, but most metrics only focus on one of these aspects. When making design choices there is a need for a concise metric which considers both detection and estimation information parameters, and then provides the user with the collection of possible optimal outcomes. In this paper a graphical analysis of Estimation and Detection Information Trade-off (EDIT) will be explored. EDIT produces curves which allow for a decision to be made for system optimization based on design constraints and costs associated with estimation and detection. EDIT analyzes the system in the estimation information and detection information space where the user is free to pick their own method of calculating these measures. The user of EDIT can choose any desired figure of merit for detection information and estimation information then the EDIT curves will provide the collection of optimal outcomes. The paper will first look at two methods of creating EDIT curves. These curves can be calculated using a wide variety of systems and finding the optimal system by maximizing a figure of merit. EDIT could also be found as an upper bound of the information from a collection of system. These two methods allow for the user to choose a method of calculation which best fits the constraints of their actual system.

  12. Field assessment of the predation risk-food availability trade-off in crab megalopae settlement.

    Directory of Open Access Journals (Sweden)

    Sebastián Tapia-Lewin

    Full Text Available Settlement is a key process for meroplanktonic organisms as it determines distribution of adult populations. Starvation and predation are two of the main mortality causes during this period; therefore, settlement tends to be optimized in microhabitats with high food availability and low predator density. Furthermore, brachyuran megalopae actively select favorable habitats for settlement, via chemical, visual and/or tactile cues. The main objective in this study was to assess the settlement of Metacarcinus edwardsii and Cancer plebejus under different combinations of food availability levels and predator presence. We determined, in the field, which factor is of greater relative importance when choosing a suitable microhabitat for settling. Passive larval collectors were deployed, crossing different scenarios of food availability and predator presence. We also explore if megalopae actively choose predator-free substrates in response to visual and/or chemical cues. We tested the response to combined visual and chemical cues and to each individually. Data was tested using a two-way factorial design ANOVA. In both species, food did not cause significant effect on settlement success, but predator presence did, therefore there was not trade-off in this case and megalopae respond strongly to predation risk by active aversion. Larvae of M. edwardsii responded to chemical and visual cues simultaneously, but there was no response to either cue by itself. Statistically, C. plebejus did not exhibit a differential response to cues, but reacted with a strong similar tendency as M. edwardsii. We concluded that crab megalopae actively select predator-free microhabitat, independently of food availability, using chemical and visual cues combined. The findings in this study highlight the great relevance of predation on the settlement process and recruitment of marine invertebrates with complex life cycles.

  13. Trade-offs between economic and environmental impacts of introducing legumes into cropping systems

    Directory of Open Access Journals (Sweden)

    Moritz eReckling

    2016-05-01

    Full Text Available Europe’s agriculture is highly specialized, dependent on external inputs and responsible for negative environmental impacts. Legume crops are grown on less than 2 % of the arable land and more than 70 % of the demand for protein feed supplement is imported from overseas. The integration of legumes into cropping systems has the potential to contribute to the transition to a more resource-efficient agriculture and reduce the current protein deficit. Legume crops influence the production of other crops in the rotation making it difficult to evaluate the overall agronomic effects of legumes in cropping systems. A novel assessment framework was developed and applied in five case study regions across Europe with the objective of evaluating trade-offs between economic and environmental effects of integrating legumes into cropping systems. Legumes resulted in positive and negative impacts when integrated into various cropping systems across the case studies. On average, cropping systems with legumes reduced nitrous oxide emissions by 18 % and 33 % and N fertilizer use by 24 % and 38 % in arable and forage systems, respectively, compared to systems without legumes. Nitrate leaching was similar with and without legumes in arable systems and reduced by 22 % in forage systems. However, grain legumes reduced gross margins in 3 of 5 regions. Forage legumes increased gross margins in 3 of 3 regions. Among the cropping systems with legumes, systems could be identified that had both relatively high economic returns and positive environmental impacts. Thus, increasing the cultivation of legumes could lead to economic competitive cropping systems and positive environmental impacts, but achieving this aim requires the development of novel management strategies informed by the involvement of advisors and farmers.

  14. What health plans do people prefer? The trade-off between premium and provider choice.

    Science.gov (United States)

    Determann, Domino; Lambooij, Mattijs S; de Bekker-Grob, Esther W; Hayen, Arthur P; Varkevisser, Marco; Schut, Frederik T; Wit, G Ardine de

    2016-09-01

    Within a healthcare system with managed competition, health insurers are expected to act as prudent buyers of care on behalf of their customers. To fulfil this role adequately, understanding consumer preferences for health plan characteristics is of vital importance. Little is known, however, about these preferences and how they vary across consumers. Using a discrete choice experiment (DCE) we quantified trade-offs between basic health plan characteristics and analysed whether there are differences in preferences according to age, health status and income. We selected four health plan characteristics to be included in the DCE: (i) the level of provider choice and associated level of reimbursement, (ii) the primary focus of provider contracting (price, quality, social responsibility), (iii) the level of service benefits, and (iv) the monthly premium. This selection was based on a literature study, expert interviews and focus group discussions. The DCE consisted of 17 choice sets, each comprising two hypothetical health plan alternatives. A representative sample (n = 533) of the Dutch adult population, based on age, gender and educational level, completed the online questionnaire during the annual open enrolment period for 2015. The final model with four latent classes showed that being able to choose a care provider freely was by far the most decisive characteristic for respondents aged over 45, those with chronic conditions, and those with a gross income over €3000/month. Monthly premium was the most important choice determinant for young, healthy, and lower income respondents. We conclude that it would be very unlikely for half of the sample to opt for health plans with restricted provider choice. However, a premium discount up to €15/month by restricted health plans might motivate especially younger, healthier, and less wealthy consumers to choose these plans. PMID:27485728

  15. Reference-dependent electric vehicle production strategy considering subsidies and consumer trade-offs

    International Nuclear Information System (INIS)

    In this paper, we extend previous reference-dependence newsvendor research by incorporating both consumer trade-offs and government subsidies to evaluate the relevant influences on the optimal electric vehicle (EV) production decisions. We present the properties of the model, derive the closed-form solutions for the model given the relevant constraints, and use numerical experiments to illustrate the results. We find that subsidies, loss aversion, the performance of both EVs and internal combustion engine-powered vehicles (ICEVs), and the coefficient of variation of demand are significant factors influencing the optimal production quantity and the expected utilities of EV production. The high selling price and other high costs of ICEVs help offset the influence of loss aversion, whereas the high costs of EV enhance loss aversion. Our study enriches the literature on subsidies for EVs by establishing a behavioral model to incorporate the decision bias in terms of loss aversion at the firm level. These findings provide guiding principles for both policymakers and EV managers for making better strategies to promote EVs in the early immature market. - Highlights: • The performance of both electric vehicles (EVs) and internal combustion engine-power vehicles (ICEVs) influences the EV production decisions. • A loss averse EV manager produces less and obtains less the expected utility than a risk neutral one. • Subsidies help decrease the EV breakeven quantity, increase the optimal quantity, offset the influence of loss aversion. • Subsidies should be adjusted according to the performance of both EVs and the ICEVs, demand heterogeneity, and local conditions. • The high ICEVs costs help offset the influence of loss aversion, whereas the high EV costs enhance loss aversion

  16. Water-carbon trade-off in China's coal power industry.

    Science.gov (United States)

    Zhang, Chao; Anadon, Laura Diaz; Mo, Hongpin; Zhao, Zhongnan; Liu, Zhu

    2014-10-01

    The energy sector is increasingly facing water scarcity constraints in many regions around the globe, especially in China, where the unprecedented large-scale construction of coal-fired thermal power plants is taking place in its extremely arid northwest regions. As a response to water scarcity, air-cooled coal power plants have experienced dramatic diffusion in China since the middle 2000s. By the end of 2012, air-cooled coal-fired thermal power plants in China amounted to 112 GW, making up 14% of China's thermal power generation capacity. But the water conservation benefit of air-cooled units is achieved at the cost of lower thermal efficiency and consequently higher carbon emission intensity. We estimate that in 2012 the deployment of air-cooled units contributed an additional 24.3-31.9 million tonnes of CO2 emissions (equivalent to 0.7-1.0% of the total CO2 emissions by China's electric power sector), while saving 832-942 million m(3) of consumptive water use (about 60% of the total annual water use of Beijing) when compared to a scenario with water-cooled plants. Additional CO2 emissions from air-cooled plants largely offset the CO2 emissions reduction benefits from Chinese policies of retiring small and outdated coal plants. This water-carbon trade-off is poised to become even more significant by 2020, as air-cooled units are expected to grow by a factor of 2-260 GW, accounting for 22% of China's total coal-fired power generation capacity.

  17. Environmental and economic trade-offs in a watershed when using corn stover for bioenergy.

    Science.gov (United States)

    Gramig, Benjamin M; Reeling, Carson J; Cibin, Raj; Chaubey, Indrajeet

    2013-02-19

    There is an abundant supply of corn stover in the United States that remains after grain is harvested which could be used to produce cellulosic biofuels mandated by the current Renewable Fuel Standard (RFS). This research integrates the Soil Water Assessment Tool (SWAT) watershed model and the DayCent biogeochemical model to investigate water quality and soil greenhouse gas flux that results when corn stover is collected at two different rates from corn-soybean and continuous corn crop rotations with and without tillage. Multiobjective watershed-scale optimizations are performed for individual pollutant-cost minimization criteria based on the economic cost of each cropping practice and (individually) the effect on nitrate, total phosphorus, sediment, or global warming potential. We compare these results with a purely economic optimization that maximizes stover production at the lowest cost without taking environmental impacts into account. We illustrate trade-offs between cost and different environmental performance criteria, assuming that nutrients contained in any stover collected must be replaced. The key finding is that stover collection using the practices modeled results in increased contributions to atmospheric greenhouse gases while reducing nitrate and total phosphorus loading to the watershed relative to the status quo without stover collection. Stover collection increases sediment loading to waterways relative to when no stover is removed for each crop rotation-tillage practice combination considered; no-till in combination with stover collection reduced sediment loading below baseline conditions without stover collection. Our results suggest that additional information is needed about (i) the level of nutrient replacement required to maintain grain yields and (ii) cost-effective management practices capable of reducing soil erosion when crop residues are removed in order to avoid contributions to climate change and water quality impairments as a result

  18. The role of python eggshell permeability dynamics in a respiration-hydration trade-off.

    Science.gov (United States)

    Stahlschmidt, Zachary R; Heulin, Benoit; DeNardo, Dale F

    2010-01-01

    Parental care is taxonomically widespread because it improves developmental conditions and thus fitness of offspring. Although relatively simplistic compared with parental behaviors of other taxa, python egg-brooding behavior exemplifies parental care because it mediates a trade-off between embryonic respiration and hydration. However, because egg brooding increases gas-exchange resistance between embryonic and nest environments and because female pythons do not adjust their brooding behavior in response to the increasing metabolic requirements of developing offspring, python egg brooding imposes hypoxic costs on embryos during the late stages of incubation. We conducted a series of experiments to determine whether eggshells coadapted with brooding behavior to minimize the negative effects of developmental hypoxia. We tested the hypotheses that python eggshells (1) increase permeability over time to accommodate increasing embryonic respiration and (2) exhibit permeability plasticity in response to chronic hypoxia. Over incubation, we serially measured the atomic and structural components of Children's python (Antaresia childreni) eggshells as well as in vivo and in vitro gas exchange across eggshells. In support of our first hypothesis, A. childreni eggshells exhibited a reduced fibrous layer, became more permeable, and facilitated greater gas exchange as incubation progressed. Our second hypothesis was not supported, as incubation O(2) concentration did not affect the shells' permeabilities to O(2) and H(2)O vapor. Our results suggest that python eggshell permeability changes during incubation but that the alterations over time are fixed and independent of environmental conditions. These findings are of broad evolutionary interest because they demonstrate that, even in relatively simple parental-care models, successful parent-offspring relationships depend on adjustments made by both the parent (i.e., egg-brooding behavioral shifts) and the offspring (i

  19. Trade-off between responsiveness and noise suppression in biomolecular system responses to environmental cues.

    Directory of Open Access Journals (Sweden)

    Alexander V Ratushny

    2011-06-01

    Full Text Available When living systems detect changes in their external environment their response must be measured to balance the need to react appropriately with the need to remain stable, ignoring insignificant signals. Because this is a fundamental challenge of all biological systems that execute programs in response to stimuli, we developed a generalized time-frequency analysis (TFA framework to systematically explore the dynamical properties of biomolecular networks. Using TFA, we focused on two well-characterized yeast gene regulatory networks responsive to carbon-source shifts and a mammalian innate immune regulatory network responsive to lipopolysaccharides (LPS. The networks are comprised of two different basic architectures. Dual positive and negative feedback loops make up the yeast galactose network; whereas overlapping positive and negative feed-forward loops are common to the yeast fatty-acid response network and the LPS-induced network of macrophages. TFA revealed remarkably distinct network behaviors in terms of trade-offs in responsiveness and noise suppression that are appropriately tuned to each biological response. The wild type galactose network was found to be highly responsive while the oleate network has greater noise suppression ability. The LPS network appeared more balanced, exhibiting less bias toward noise suppression or responsiveness. Exploration of the network parameter space exposed dramatic differences in system behaviors for each network. These studies highlight fundamental structural and dynamical principles that underlie each network, reveal constrained parameters of positive and negative feedback and feed-forward strengths that tune the networks appropriately for their respective biological roles, and demonstrate the general utility of the TFA approach for systems and synthetic biology.

  20. Trade-Offs of Flowering and Maturity Synchronisation for Pineapple Quality.

    Directory of Open Access Journals (Sweden)

    V Nicodème Fassinou Hotegni

    Full Text Available In the pineapple sector of Benin, poor fruit quality prevents pineapple producers to enter the European market. We investigated effects of common cultural practices, flowering and maturity synchronisation, (1 to quantify the trade-offs of flowering and maturity synchronisation for pineapple quality and the proportion of fruits exportable to European markets, and (2 to determine the effect of harvesting practice on quality attributes. Four on-farm experiments were conducted during three years using cultivars Sugarloaf and Smooth Cayenne. A split-split plot design was used in each experiment, with flowering induction practice as main factor (artificial or natural flowering induction, maturity induction practice as split factor (artificial or natural maturity induction and harvesting practice as the split-split factor (farmers' harvest practice or individual fruit harvesting at optimum maturity. Artificial flowering induction gave fruits with lower infructescence weight, higher ratio crown: infructescence length, and a lower proportion of fruits exportable to European markets than natural flowering induction. The costs of the improvements by natural flowering induction were huge: the longer durations from planting to flowering induction and harvesting, the higher number of harvestings of the fruits increasing the labour cost and the lower proportion of plants producing fruits compared with crops from artificially flowering-induced plants. Artificial maturity induction decreased the total soluble solids concentration in the fruits compared with natural maturity induction thus decreasing the proportion of fruits exportable to European markets, at a benefit of only a slightly shorter time from flowering induction to harvesting. Harvesting individual fruits at optimum maturity gave fruits with higher total soluble solids in naturally maturity induced fruits compared with the farmers' harvest practice. Given the huge costs of natural flowering induction

  1. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient

    Science.gov (United States)

    Dostálek, Tomáš; Rokaya, Maan Bahadur; Maršík, Petr; Rezek, Jan; Skuhrovec, Jiří; Pavela, Roman; Münzbergová, Zuzana

    2016-01-01

    The type and intensity of plant–herbivore interactions are likely to be altered under climate change as a consequence of differential dispersal rates of plants and their herbivores. Here, we studied variation in herbivore damage on Salvia nubicola in the field and compared its growth and defence strategies against herbivores in controlled conditions using seeds from populations along a broad altitudinal gradient. Our work is one of the first studies to simultaneously measure complex intraspecific variation in plant growth, direct and indirect defences as well as plant tolerance (ability to regrow) as a consequence of herbivore attack simulated by clipping. In the field, we found that plants experienced higher herbivore pressure in lower altitudes. In the greenhouse, plants grown from seeds collected in lower-altitude populations grew better and produced a higher content of phenolic compounds (direct defence) and volatile organic compounds (indirect defence) in response to simulated herbivory. However, there were no differences in tolerance and effect of S. nubicola extracts on the model generalist herbivore Spodoptera littoralis (direct defence) along the altitudinal gradient. Although we found that S. nubicola developed a range of defence strategies, the strategies do not seem to be used simultaneously in all populations even though most of them are correlated with altitudinal gradient. Our finding is in agreement with the current knowledge that co-expression of multiple defences might be costly for a plant, since investment in defensive traits is assumed to reduce the resource availability for growth and reproduction. Our study thus shows the importance of simultaneous study of different defence strategies since understanding these trade-offs could be necessary for detecting the mechanisms by which plants are able to cope with future climate change. PMID:27169609

  2. Social-environmental trade-offs for Systems of Rice Intensification in S. India

    Science.gov (United States)

    Gathorne-Hardy, A.; Reddy, D. N.; Motkuri, V.; Harriss-White, B.

    2014-12-01

    Agricultural systems will only be sustainable if social and economic considerations are included in their design. Systems of Rice Intensification (SRI) has been proposed as more sustainable form of rice production due to reported higher yields and lower greenhouse gas (GHG) emissions. However there is a research gap concerning the wider social and economic implications of SRI. We developed a model to simultaneously analyse social, economic and environmental sustainability indicators (GHG emissions, ground water use, fossil/ non-fossil energy use, costs, profits, gender, employment quality and employment quantity) to compare SRI to conventional flooded rice production systems. Data was based on farmer-recall questionnaires in Andhra Pradesh, India. Data was collected per hectare and per kg of paddy. SRI substantially increased yields (157% of control), reduced ground-water requirements (64% ha-1, 42% kg-1, of control) and reduced GHG emissions (72% ha-1, 42% kg-1, of control). Costs were substantially lower for SRI systems, on both a hectare and a per kg basis. The high yields and lower costs resulted in a doubling of profits per hectare. However, these benefits are accrued to the farmer potentially at the expense of landless labourers. The role of agricultural employment in developing countries is a controversial issue, but in India, whose substantial economic growth has been largely jobless, agriculture retains a key role in reducing under- and un- employment. SRI labour demand was lower (70% of control ha-1). Simultaneously the ratio of male to female employment increased, from 67% female labour in control to 50% SRI. Thus trade-offs may exist between environmental, economic and social aspects of SRI. Understanding sustainability from a broad perspective facilitates better policy creation.

  3. Behavioral Thermoregulation and Trade-Offs in Juvenile Lobster Homarus americanus.

    Science.gov (United States)

    Nielsen, Travis V; McGaw, Iain J

    2016-02-01

    Water temperature influences the behavior and distribution patterns of both larval and adult American lobster Homarus americanus. However, very little is known about the responses of juvenile lobsters. The juvenile life stage is a critical period; high levels of mortality, combined with specific behavioral responses, can disconnect larval settlement from patterns of abundance of adults. We assessed behavioral thermoregulation in juvenile lobsters, and determined how thermal preferences can be altered by the presence of shelter and food. Juvenile lobsters avoided temperatures higher than 20 °C and lower than 8 °C, and had a mean temperature preference of 16.2 ± 1 °C. This preference was unaffected by prior acclimation, origin (laboratory-raised or wild), or size. When the animals were subjected to a temperature change (5-20 °C), activity rates peaked at 15 °C, and remained stable thereafter. Activity rates did not change when a shelter was added. The addition of food resulted in an increase in activity associated with food handling. When juvenile lobsters were offered a choice between temperature, shelter, and food, they always chose the environment with a shelter, even when it was in a thermally unfavorable temperature. Juveniles also spent more time in a thermally unfavorable environment when food was present; however, acquisition of a shelter was prioritized over food. Although juveniles had a similar thermal preference to adults, they are more vulnerable to predation; the innate shelter-seeking behavior of juveniles overrode their thermal preference. While temperature is an important environmental factor affecting the physiology, distribution, and growth of aquatic ectotherms, our findings suggest that trade-off behaviors occur in order to maintain optimal fitness and survival of the individual. PMID:26896176

  4. Network dynamics underlying speed-accuracy trade-offs in response to errors.

    Directory of Open Access Journals (Sweden)

    Yigal Agam

    Full Text Available The ability to dynamically and rapidly adjust task performance based on its outcome is fundamental to adaptive, flexible behavior. Over trials of a task, responses speed up until an error is committed and after the error responses slow down. These dynamic adjustments serve to optimize performance and are well-described by the speed-accuracy trade-off (SATO function. We hypothesized that SATOs based on outcomes reflect reciprocal changes in the allocation of attention between the internal milieu and the task-at-hand, as indexed by reciprocal changes in activity between the default and dorsal attention brain networks. We tested this hypothesis using functional MRI to examine the pattern of network activation over a series of trials surrounding and including an error. We further hypothesized that these reciprocal changes in network activity are coordinated by the posterior cingulate cortex (PCC and would rely on the structural integrity of its white matter connections. Using diffusion tensor imaging, we examined whether fractional anisotropy of the posterior cingulum bundle correlated with the magnitude of reciprocal changes in network activation around errors. As expected, reaction time (RT in trials surrounding errors was consistent with predictions from the SATO function. Activation in the default network was: (i inversely correlated with RT, (ii greater on trials before than after an error and (iii maximal at the error. In contrast, activation in the right intraparietal sulcus of the dorsal attention network was (i positively correlated with RT and showed the opposite pattern: (ii less activation before than after an error and (iii the least activation on the error. Greater integrity of the posterior cingulum bundle was associated with greater reciprocity in network activation around errors. These findings suggest that dynamic changes in attention to the internal versus external milieu in response to errors underlie SATOs in RT and are mediated

  5. Regional drivers of clutch loss reveal important trade-offs for beach-nesting birds

    Science.gov (United States)

    Schlacher, Thomas A.; Weston, Michael A.; Huijbers, Chantal M.; Anderson, Chris; Gilby, Ben L.; Olds, Andrew D.; Connolly, Rod M.; Schoeman, David S.

    2016-01-01

    Coastal birds are critical ecosystem constituents on sandy shores, yet are threatened by depressed reproductive success resulting from direct and indirect anthropogenic and natural pressures. Few studies examine clutch fate across the wide range of environments experienced by birds; instead, most focus at the small site scale. We examine survival of model shorebird clutches as an index of true clutch survival at a regional scale (∼200 km), encompassing a variety of geomorphologies, predator communities, and human use regimes in southeast Queensland, Australia. Of the 132 model nests deployed and monitored with cameras, 45 (34%) survived the experimental exposure period. Thirty-five (27%) were lost to flooding, 32 (24%) were depredated, nine (7%) buried by sand, seven (5%) destroyed by people, three (2%) failed by unknown causes, and one (1%) was destroyed by a dog. Clutch fate differed substantially among regions, particularly with respect to losses from flooding and predation. ‘Topographic’ exposure was the main driver of mortality of nests placed close to the drift line near the base of dunes, which were lost to waves (particularly during storms) and to a lesser extent depredation. Predators determined the fate of clutches not lost to waves, with the depredation probability largely influenced by region. Depredation probability declined as nests were backed by higher dunes and were placed closer to vegetation. This study emphasizes the scale at which clutch fate and survival varies within a regional context, the prominence of corvids as egg predators, the significant role of flooding as a source of nest loss, and the multiple trade-offs faced by beach-nesting birds and those that manage them. PMID:27672510

  6. FAST Conformational Searches by Balancing Exploration/Exploitation Trade-Offs.

    Science.gov (United States)

    Zimmerman, Maxwell I; Bowman, Gregory R

    2015-12-01

    Molecular dynamics simulations are a powerful means of understanding conformational changes. However, it is still difficult to simulate biologically relevant time scales without the use of specialized supercomputers. Here, we introduce a goal-oriented sampling method, called fluctuation amplification of specific traits (FAST), for extending the capabilities of commodity hardware. This algorithm rapidly searches conformational space for structures with desired properties by balancing trade-offs between focused searches around promising solutions (exploitation) and trying novel solutions (exploration). FAST was inspired by the hypothesis that many physical properties have an overall gradient in conformational space, akin to the energetic gradients that are known to guide proteins to their folded states. For example, we expect that transitioning from a conformation with a small solvent-accessible surface area to one with a large surface area will require passing through a series of conformations with steadily increasing surface areas. We demonstrate that such gradients are common through retrospective analysis of existing Markov state models (MSMs). Then we design the FAST algorithm to exploit these gradients to find structures with desired properties by (1) recognizing and amplifying structural fluctuations along gradients that optimize a selected physical property whenever possible, (2) overcoming barriers that interrupt these overall gradients, and (3) rerouting to discover alternative paths when faced with insurmountable barriers. To test FAST, we compare its performance to other methods for three common types of problems: (1) identifying unexpected binding pockets, (2) discovering the preferred paths between specific structures, and (3) folding proteins. Our conservative estimate is that FAST outperforms conventional simulations and an adaptive sampling algorithm by at least an order of magnitude. Furthermore, FAST yields both the proper thermodynamics and

  7. Seasonal migration determined by a trade-off between predator avoidance and growth.

    Directory of Open Access Journals (Sweden)

    Christer Brönmark

    Full Text Available Migration is a common phenomenon in many organisms, terrestrial as well as aquatic, and considerable effort has been spent to understand the evolution of migratory behaviour and its consequences for population and community dynamics. In aquatic systems, studies on migration have mainly been focused on commercially important fish species, such as salmon and trout. However, seasonal mass-migrations may occur also among other freshwater fish, e.g. in cyprinids that leave lakes and migrate into streams and wetlands in the fall and return back to the lake in spring. In a conceptual model, we hypothesized that this is an adaptive behaviour in response to seasonal changes in predation (P and growth (G and that migrating fish change habitat so as to minimise the ratio between predation mortality and growth rate (P/G. Estimates from bioenergetic modelling showed that seasonal changes in the ratio between predator consumption rate and prey growth rate followed the predictions from the conceptual model and also gave more precise predictions for the timing of the habitat change. By quantifying the migration of more than 1800 individually marked fish, we showed that actual migration patterns followed predictions with a remarkable accuracy, suggesting that migration patterns have evolved in response to seasonally fluctuating trade-offs between predator avoidance and foraging gains. Thus, the conceptual model provides a mechanistic understanding to mass-migration in prey fish. Further, we also show that the dominant prey fish is actually absent from the lake during a major part of the year, which should have strong implications for the dynamics of the lake ecosystem through direct and indirect food-web interactions.

  8. FAST Conformational Searches by Balancing Exploration/Exploitation Trade-Offs.

    Science.gov (United States)

    Zimmerman, Maxwell I; Bowman, Gregory R

    2015-12-01

    Molecular dynamics simulations are a powerful means of understanding conformational changes. However, it is still difficult to simulate biologically relevant time scales without the use of specialized supercomputers. Here, we introduce a goal-oriented sampling method, called fluctuation amplification of specific traits (FAST), for extending the capabilities of commodity hardware. This algorithm rapidly searches conformational space for structures with desired properties by balancing trade-offs between focused searches around promising solutions (exploitation) and trying novel solutions (exploration). FAST was inspired by the hypothesis that many physical properties have an overall gradient in conformational space, akin to the energetic gradients that are known to guide proteins to their folded states. For example, we expect that transitioning from a conformation with a small solvent-accessible surface area to one with a large surface area will require passing through a series of conformations with steadily increasing surface areas. We demonstrate that such gradients are common through retrospective analysis of existing Markov state models (MSMs). Then we design the FAST algorithm to exploit these gradients to find structures with desired properties by (1) recognizing and amplifying structural fluctuations along gradients that optimize a selected physical property whenever possible, (2) overcoming barriers that interrupt these overall gradients, and (3) rerouting to discover alternative paths when faced with insurmountable barriers. To test FAST, we compare its performance to other methods for three common types of problems: (1) identifying unexpected binding pockets, (2) discovering the preferred paths between specific structures, and (3) folding proteins. Our conservative estimate is that FAST outperforms conventional simulations and an adaptive sampling algorithm by at least an order of magnitude. Furthermore, FAST yields both the proper thermodynamics and

  9. Seed size-number trade-off in Euterpe edulis in plant communities of the Atlantic Forest

    OpenAIRE

    Pedro Henrique Santin Brancalion; Ricardo Ribeiro Rodrigues

    2014-01-01

    Investigations of seed size and number differences among plant populations growing in contrasting habitats can provide relevant information about ecological strategies that optimize reproductive effort. This may imply important consequences for biodiversity conservation and restoration. Therefore, we sought to investigate seed size-number trade-off in Euterpe edulis populations growing in plant communities in the Brazilian Atlantic Forest. Seed dry mass and seed number per bunch were evaluate...

  10. When to stay, when to go: trade-offs for southern African arid-zone birds in times of drought

    OpenAIRE

    Dean, W. R. J.; Anderson, M. D.; Barnard, P.

    2009-01-01

    Arid environments remind one of the punctuated equilibriumtheory of evolution: they experience long periods of stasis and low productivity, interrupted with episodic rainfall which spurs reproduction and movement. Birds, as highly dispersive organisms, are among the most dramatic indicators of these fluctuations. Here we review birds’ two main strategies, residency and nomadism, and the trade-offs faced by individuals in uncertain times. In general, wet years stimulate higher densities of nes...

  11. Patterns of sperm damage in Chernobyl passerine birds suggest a trade-off between sperm length and integrity

    OpenAIRE

    Hermosell, Ignacio G.; Laskemoen, Terje; Rowe, Melissah; Møller, Anders P.; Mousseau, Timothy A; Albrecht, Tomáš; Lifjeld, Jan T

    2013-01-01

    Interspecific variation in sperm size is enigmatic, but generally assumed to reflect species-specific trade-offs in selection pressures. Among passerine birds, sperm length varies sevenfold, and sperm competition risk seems to drive the evolution of longer sperm. However, little is known about factors favouring short sperm or constraining the evolution of longer sperm. Here, we report a comparative analysis of sperm head abnormalities among 11 species of passerine bird in Chernobyl, presumabl...

  12. Sperm velocity and longevity trade off each other and influence fertilization in the sea urchin Lytechinus variegatus.

    OpenAIRE

    Levitan, D R

    2000-01-01

    The theoretical prediction that fast sperm should be more effective at fertilizing eggs has never been documented empirically. Interspecific comparisons suggest an inverse relationship between sperm velocity and sperm longevity but this trade-off has never been demonstrated within a species. Here I investigate how sperm velocity and sperm longevity influence the patterns of fertilization in the sea urchin Lytechinus variegatus. In the laboratory I examined 11 male female pairs of sea urchins ...

  13. The Early Labour Market Effects of Generally and Vocationally Oriented Higher Education: Is There a Trade-off?

    OpenAIRE

    Verhaest, Dieter; Baert, Stijn

    2015-01-01

    This study investigates whether the choice for a vocationally versus a generally oriented higher education program entails a trade-off between higher employment chances and better matches at the start of the career (when opting for a vocational orientation) and a lower risk of bad match persistence later on (when opting for a general orientation). We rely on detailed early career spell data of Flemish graduates and assess the vocational orientation of their program by means of the presence of...

  14. Selection on defensive traits in a sterile caste - caste evolution: a mechanism to overcome life-history trade-offs?

    Science.gov (United States)

    Roux, Estelle A; Roux, Maurice; Korb, Judith

    2009-01-01

    During development and evolution individuals generally face a trade-off between the development of weapons and gonads. In termites, characterized by reproductive division of labor, a caste evolved-the soldiers-which is completely sterile and which might be released from developmental trade-offs between weapons and testes. These soldiers are exclusively dedicated to defense. First, we investigated whether defensive traits are under selection in sterile termite soldiers using allometric analyses. In soldiers of the genus Cryptotermes phragmotic traits such as a sculptured and foreshortened head evolve rapidly but were also lost twice. Second, we compared the scaling relationships of these weapons with those in solitary insects facing a trade-off between weapons and gonads. Defensive traits consistently had lower slopes than nondefensive traits which supports the existence of stabilizing selection on soldier phragmotic traits in order to plug galleries. Moreover, soldier head widths were colony specific and correlated with the minimum gallery diameter of a colony. This can proximately be explained by soldiers developing from different instars. The scaling relationships of these termite soldiers contrast strikingly with those of weapons of solitary insects, which are generally exaggerated (i.e., overscaling) male traits. These differences may provide important insights into trait evolution. Trade-offs constraining the development of individuals may have been uncoupled in termites by evolving different castes, each specialized for one function. When individuals in social insect are "released" from developmental constraints through the evolution of castes, this certainly contributed to the ecological and evolutionary success of social insects. PMID:19196335

  15. Using Flow-Ecology Relationships to Evaluate Ecosystem Service Trade-Offs and Complementarities in the Nation's Largest River Swamp

    Science.gov (United States)

    Kozak, Justin P.; Bennett, Micah G.; Hayden-Lesmeister, Anne; Fritz, Kelley A.; Nickolotsky, Aaron

    2015-06-01

    Large river systems are inextricably linked with social systems; consequently, management decisions must be made within a given ecological, social, and political framework that often defies objective, technical resolution. Understanding flow-ecology relationships in rivers is necessary to assess potential impacts of management decisions, but translating complex flow-ecology relationships into stakeholder-relevant information remains a struggle. The concept of ecosystem services provides a bridge between flow-ecology relationships and stakeholder-relevant data. Flow-ecology relationships were used to explore complementary and trade-off relationships among 12 ecosystem services and related variables in the Atchafalaya River Basin, Louisiana. Results from Indicators of Hydrologic Alteration were reduced to four management-relevant hydrologic variables using principal components analysis. Multiple regression was used to determine flow-ecology relationships and Pearson correlation coefficients, along with regression results, were used to determine complementary and trade-off relationships among ecosystem services and related variables that were induced by flow. Seven ecosystem service variables had significant flow-ecology relationships for at least one hydrologic variable ( R 2 = 0.19-0.64). River transportation and blue crab ( Callinectes sapidus) landings exhibited a complementary relationship mediated by flow; whereas transportation and crawfish landings, crawfish landings and crappie ( Pomoxis spp.) abundance, and blue crab landings and blue catfish ( Ictalurus furcatus) abundance exhibited trade-off relationships. Other trade-off and complementary relationships among ecosystem services and related variables, however, were not related to flow. These results give insight into potential conflicts among stakeholders, can reduce the dimensions of management decisions, and provide initial hypotheses for experimental flow modifications.

  16. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies

    OpenAIRE

    Raine, Nigel E.; Chittka, Lars

    2012-01-01

    Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris) were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals ...

  17. The trade-off between Innovation and Defence Industrial Policy - A Simulation Model Analysis of the Norwegian Defence Industry

    OpenAIRE

    Castellacci, Fulvio; Blom, Martin; Fevolden, Arne Martin

    2012-01-01

    The paper investigates the trade-off between innovation and defence industrial policy. It presents an agent-based simulation model calibrated for the Norwegian defence industry that compares different policy scenarios and examines the effects of a pending EU market liberalization process. The paper points to two main results. (1) It finds that a pure scenario where national authorities focus on, and provide support exclusively for, either a) international competitiveness or b) national defenc...

  18. Selection for cuticular melanism reveals immune function and life-history trade-offs in Spodoptera littoralis

    OpenAIRE

    Cotter, S. C.; Myatt, J. P.; Benskin, C. M. H.; Wilson, K.

    2008-01-01

    Several insect species show an increase in cuticular melanism in response to high densities. In some species, there is evidence that this melanism is correlated with an up-regulation of certain immune system components, particularly phenoloxidase (PO) activity, and with the down-regulation of lysozyme activity, suggesting a trade-off between the two traits. As melanism has a genetic component, we selected both melanic and nonmelanic lines of the phase-polyphenic lepidopteran, Spodoptera litto...

  19. Viruses' Life History: Towards a Mechanistic Basis of a Trade-Off between Survival and Reproduction among Phages.

    OpenAIRE

    Marianne De Paepe; François Taddei

    2006-01-01

    Life history theory accounts for variations in many traits involved in the reproduction and survival of living organisms, by determining the constraints leading to trade-offs among these different traits. The main life history traits of phages-viruses that infect bacteria-are the multiplication rate in the host, the survivorship of virions in the external environment, and their mode of transmission. By comparing life history traits of 16 phages infecting the bacteria Escherichia coli, we show...

  20. Life-history trade-offs during the seed-to-seedling transition in a subtropical wet forest community

    OpenAIRE

    Muscarella, Robert; Uriarte, Maria; Forero-Montana, Jimena; Comita, Liza S.; Nathan G Swenson; Thompson, Jill; Nytch, Christopher J.; Zimmerman, Jess K; Jonckheere, Inge

    2013-01-01

    The transition from seed to established seedling (STS) represents a major bottleneck in plant demography with implications for community dynamics and the maintenance of species diversity. The relative strength of seed limitation versus seedling establishment limitation can reveal life-history trade-offs that contribute to the maintenance of community diversity. If seed limitation dominates, chance arrival to open sites may play a key role in maintaining diversity. If seedling establishment li...

  1. A trade-off between reproduction and a condition-dependent sexually selected ornament in the house sparrow Passer domesticus.

    OpenAIRE

    Griffith, S. C.

    2000-01-01

    Reproductive effort was manipulated in a free-living population of house sparrows (Passer domesticus) to investigate the trade-off between reproductive investment and the expression of a condition-dependent sexually selected ornament. Phenotypic plasticity in the expression of this trait was related to the experimentally manipulated size of the brood reared by a male. Males that invested more in current reproduction subsequently became more attractive to females in this population as they sho...

  2. Are personality differences in a small iteroparous mammal maintained by a life-history trade-off?

    OpenAIRE

    Dammhahn, Melanie

    2012-01-01

    Despite increasing interest, animal personality is still a puzzling phenomenon. Several theoretical models have been proposed to explain intraindividual consistency and interindividual variation in behaviour, which have been primarily supported by qualitative data and simulations. Using an empirical approach, I tested predictions of one main life-history hypothesis, which posits that consistent individual differences in behaviour are favoured by a trade-off between current and future reproduc...

  3. TRADE-OFFS BETWEEN ECONOMIC EFFICIENCY AND CONTAMINATION BY COFFEE PROCESSING A BIOECONOMIC MODEL AT THE WATERSHED LEVEL IN HONDURAS

    OpenAIRE

    Barbier, Bruno; Hearne, Robert R.; Gonzalez, Jose Manuel; Nelson, Andy; Castaneda, Orlando Mejia

    2003-01-01

    In Honduras, traditional coffee processing is the cause of two major problems: poor coffee quality and contaminated water. In this paper we present a method that determines the trade-off between economic efficiency and contamination in a Honduran sub-watershed. The method is a bioeconomic model based on mathematical programming that stimulates the functioning of the interlinked economic and ecological processes in the sub-watershed. We compare various scenarii where the model is given the pos...

  4. Thermoelectric energy converters under a trade-off figure of merit with broken time-reversal symmetry

    OpenAIRE

    Iyyappan, I.; Ponmurugan, M.

    2016-01-01

    We study the optimum performance of the thermoelectric energy converters such as heat engines and refrigerators with broken time-reversal symmetry by applying unified trade-off figure of merit $\\dot{\\Omega}$, which takes the account of best compromise between the maximum work extraction and the minimum work loss. We find that the maximum $\\dot{\\Omega}$ criterion provide the significantly high performance of the thermoelectric energy converter if the system possess reasonably large value of th...

  5. Exploring trade-offs between fisheries and conservation of the vaquita porpoise (Phocoena sinus using an Atlantis ecosystem model.

    Directory of Open Access Journals (Sweden)

    Hem Nalini Morzaria-Luna

    Full Text Available BACKGROUND: Minimizing fishery bycatch threats might involve trade-offs between maintaining viable populations and economic benefits. Understanding these trade-offs can help managers reconcile conflicting goals. An example is a set of bycatch reduction measures for the Critically Endangered vaquita porpoise (Phocoena sinus, in the Northern Gulf of California, Mexico. The vaquita is an endemic species threatened with extinction by artisanal net bycatch within its limited range; in this area fisheries are the chief source of economic productivity. METHODOLOGY/PRINCIPAL FINDINGS: We analyze trade-offs between conservation of the vaquita and fisheries, using an end-to-end Atlantis ecosystem model for the Northern Gulf of California. Atlantis is a spatially-explicit model intended as a strategic tool to test alternative management strategies. We simulated increasingly restrictive fisheries regulations contained in the vaquita conservation plan: implementing progressively larger spatial management areas that exclude gillnets, shrimp driftnets and introduce a fishing gear that has no vaquita bycatch. We found that only the most extensive spatial management scenarios recovered the vaquita population above the threshold necessary to downlist the species from Critically Endangered. The scenario that excludes existing net gear from the 2008 area of vaquita distribution led to moderate decrease in net present value (US$ 42 million relative to the best-performing scenario and a two-fold increase in the abundance of adult vaquita over the course of 30 years. CONCLUSIONS/SIGNIFICANCE: Extended spatial management resulted in the highest recovery of the vaquita population. The economic cost of proposed management actions was unequally divided between fishing fleets; the loss of value from finfish gillnet fisheries was never recovered. Our analysis shows that managers will have to confront difficult trade-offs between management scenarios for vaquita conservation.

  6. No evidence of trade-offs in the evolution of sperm numbers and sperm size in mammals.

    Science.gov (United States)

    Tourmente, M; Delbarco Trillo, J; Roldan, E R S

    2015-10-01

    Post-copulatory sexual selection, in the form sperm competition, has influenced the evolution of several male reproductive traits. However, theory predicts that sperm competition would lead to trade-offs between numbers and size of spermatozoa because increased costs per cell would result in a reduction of sperm number if both traits share the same energetic budget. Theoretical models have proposed that, in large animals, increased sperm size would have minimal fitness advantage compared with increased sperm numbers. Thus, sperm numbers would evolve more rapidly than sperm size under sperm competition pressure. We tested in mammals whether sperm competition maximizes sperm numbers and size, and whether there is a trade-off between these traits. Our results showed that sperm competition maximizes sperm numbers in eutherian and metatherian mammals. There was no evidence of a trade-off between sperm numbers and sperm size in any of the two mammalian clades as we did not observe any significant relationship between sperm numbers and sperm size once the effect of sperm competition was taken into account. Maximization of both numbers and size in mammals may occur because each trait is crucial at different stages in sperm's life; for example size-determined sperm velocity is a key determinant of fertilization success. In addition, numbers and size may also be influenced by diverse energetic budgets required at different stages of sperm formation. PMID:26190170

  7. Achieving the triple bottom line in the face of inherent trade-offs among social equity, economic return, and conservation.

    Science.gov (United States)

    Halpern, Benjamin S; Klein, Carissa J; Brown, Christopher J; Beger, Maria; Grantham, Hedley S; Mangubhai, Sangeeta; Ruckelshaus, Mary; Tulloch, Vivitskaia J; Watts, Matt; White, Crow; Possingham, Hugh P

    2013-04-01

    Triple-bottom-line outcomes from resource management and conservation, where conservation goals and equity in social outcomes are maximized while overall costs are minimized, remain a highly sought-after ideal. However, despite widespread recognition of the importance that equitable distribution of benefits or costs across society can play in conservation success, little formal theory exists for how to explicitly incorporate equity into conservation planning and prioritization. Here, we develop that theory and implement it for three very different case studies in California (United States), Raja Ampat (Indonesia), and the wider Coral Triangle region (Southeast Asia). We show that equity tends to trade off nonlinearly with the potential to achieve conservation objectives, such that similar conservation outcomes can be possible with greater equity, to a point. However, these case studies also produce a range of trade-off typologies between equity and conservation, depending on how one defines and measures social equity, including direct (linear) and no trade-off. Important gaps remain in our understanding, most notably how equity influences probability of conservation success, in turn affecting the actual ability to achieve conservation objectives. Results here provide an important foundation for moving the science and practice of conservation planning-and broader spatial planning in general-toward more consistently achieving efficient, equitable, and effective outcomes. PMID:23530207

  8. Individual heterogeneity and offspring sex affect the growth-reproduction trade-off in a mammal with indeterminate growth.

    Science.gov (United States)

    Gélin, Uriel; Wilson, Michelle E; Cripps, Jemma; Coulson, Graeme; Festa-Bianchet, Marco

    2016-04-01

    Reproduction can lead to a trade-off with growth, particularly when individuals reproduce before completing body growth. Kangaroos have indeterminate growth and may always face this trade-off. We combined an experimental manipulation of reproductive effort and multi-year monitoring of a large sample size of marked individuals in two populations of eastern grey kangaroos to test the predictions (1) that reproduction decreases skeletal growth and mass gain and (2) that mass loss leads to reproductive failure. We also tested if sex-allocation strategies influenced these trade-offs. Experimental reproductive suppression revealed negative effects of reproduction on mass gain and leg growth from 1 year to the next. Unmanipulated females, however, showed a positive correlation between number of days lactating and leg growth over periods of 2 years and longer, suggesting that over the long term, reproductive costs were masked by individual heterogeneity in resource acquisition. Mass gain was necessary for reproductive success the subsequent year. Although mothers of daughters generally lost more mass than females nursing sons, mothers in poor condition experienced greater mass gain and arm growth if they had daughters than if they had sons. The strong links between individual mass changes and reproduction suggest that reproductive tactics are strongly resource-dependent.

  9. Life-history evolution in the anthropocene: effects of increasing nutrients on traits and trade-offs.

    Science.gov (United States)

    Snell-Rood, Emilie; Cothran, Rickey; Espeset, Anne; Jeyasingh, Punidan; Hobbie, Sarah; Morehouse, Nathan I

    2015-08-01

    Variation in life-history traits can have major impacts on the ecological and evolutionary responses of populations to environmental change. Life-history variation often results from trade-offs that arise because individuals have a limited pool of resources to allocate among traits. However, human activities are increasing the availability of many once-limited resources, such as nitrogen and phosphorus, with potentially major implications for the expression and evolution of life-history trade-offs. In this review, we synthesize contemporary life history and sexual selection literature with current research on ecosystem nutrient cycling to highlight novel opportunities presented by anthropogenic environmental change for investigating life-history trait development and evolution. Specifically, we review four areas where nutrition plays a pivotal role in life-history evolution and explore possible implications in the face of rapid, human-induced change in nutrient availability. For example, increases in the availability of nutrients may relax historical life-history trade-offs and reduce the honesty of signaling systems. We argue that ecosystems experiencing anthropogenic nutrient inputs present a powerful yet underexplored arena for testing novel and longstanding questions in organismal life-history evolution. PMID:26240602

  10. Achieving the triple bottom line in the face of inherent trade-offs among social equity, economic return, and conservation.

    Science.gov (United States)

    Halpern, Benjamin S; Klein, Carissa J; Brown, Christopher J; Beger, Maria; Grantham, Hedley S; Mangubhai, Sangeeta; Ruckelshaus, Mary; Tulloch, Vivitskaia J; Watts, Matt; White, Crow; Possingham, Hugh P

    2013-04-01

    Triple-bottom-line outcomes from resource management and conservation, where conservation goals and equity in social outcomes are maximized while overall costs are minimized, remain a highly sought-after ideal. However, despite widespread recognition of the importance that equitable distribution of benefits or costs across society can play in conservation success, little formal theory exists for how to explicitly incorporate equity into conservation planning and prioritization. Here, we develop that theory and implement it for three very different case studies in California (United States), Raja Ampat (Indonesia), and the wider Coral Triangle region (Southeast Asia). We show that equity tends to trade off nonlinearly with the potential to achieve conservation objectives, such that similar conservation outcomes can be possible with greater equity, to a point. However, these case studies also produce a range of trade-off typologies between equity and conservation, depending on how one defines and measures social equity, including direct (linear) and no trade-off. Important gaps remain in our understanding, most notably how equity influences probability of conservation success, in turn affecting the actual ability to achieve conservation objectives. Results here provide an important foundation for moving the science and practice of conservation planning-and broader spatial planning in general-toward more consistently achieving efficient, equitable, and effective outcomes.

  11. Seed size-number trade-off in Euterpe edulis in plant communities of the Atlantic Forest

    Directory of Open Access Journals (Sweden)

    Pedro Henrique Santin Brancalion

    2014-06-01

    Full Text Available Investigations of seed size and number differences among plant populations growing in contrasting habitats can provide relevant information about ecological strategies that optimize reproductive effort. This may imply important consequences for biodiversity conservation and restoration. Therefore, we sought to investigate seed size-number trade-off in Euterpe edulis populations growing in plant communities in the Brazilian Atlantic Forest. Seed dry mass and seed number per bunch were evaluated in 2008 and 2009 in large remnants of the Seasonally Dry Forest, Restinga Forest and Atlantic Rainforest in southeastern Brazil, in 20 individuals per site and year. Seed size and seed number varied among forest types, but a seed size-number trade-off was neither observed within nor among populations. Positive association between seed size and number was found in the Atlantic Rainforest, and reduced seed crop was not accompanied by heavier seeds in the Restinga Forest. Seed dry mass declined in 2009 in all three forest types. Compared to seed number in 2008, palms of both the Restinga Forest and the Atlantic Rainforest produced in 2009 higher yields of smaller seeds - evidence of between years seed size-number trade-off -, while the Seasonally Dry Forest population produced a reduced number of smaller seeds. Such a flexible reproductive strategy, involving neutral, positive, and negative associations between seed size and number could enhance the ecological amplitude of this species and their potential to adapt to different environment conditions.

  12. The evolution of the competition-dispersal trade-off affects α- and β-diversity in a heterogeneous metacommunity.

    Science.gov (United States)

    Laroche, Fabien; Jarne, Philippe; Perrot, Thomas; Massol, Francois

    2016-04-27

    Difference in dispersal ability is a key driver of species coexistence in metacommunities. However, the available frameworks for interpreting species diversity patterns in natura often overlook trade-offs and evolutionary constraints associated with dispersal. Here, we build a metacommunity model accounting for dispersal evolution and a competition-dispersal trade-off. Depending on the distribution of carrying capacities among communities, species dispersal values are distributed either around a single strategy (evolutionarily stable strategy, ESS), or around distinct strategies (evolutionary branching, EB). We show that limited dispersal generates spatial aggregation of dispersal traits in ESS and EB scenarios, and that the competition-dispersal trade-off strengthens the pattern in the EB scenario. Importantly, individuals in larger (respectively (resp.) smaller) communities tend to harbour lower (resp. higher) dispersal, especially under the EB scenario. We explore how dispersal evolution affects species diversity patterns by comparing those from our model to the predictions of a neutral metacommunity model. The most marked difference is detected under EB, with distinctive values of both α- and β-diversity (e.g. the dissimilarity in species composition between small and large communities was significantly larger than neutral predictions). We conclude that, from an empirical perspective, jointly assessing community carrying capacity with species dispersal strategies should improve our understanding of diversity patterns in metacommunities.

  13. Capturing ecosystem services, stakeholders' preferences and trade-offs in coastal aquaculture decisions: a Bayesian belief network application.

    Science.gov (United States)

    Schmitt, Laetitia Helene Marie; Brugere, Cecile

    2013-01-01

    Aquaculture activities are embedded in complex social-ecological systems. However, aquaculture development decisions have tended to be driven by revenue generation, failing to account for interactions with the environment and the full value of the benefits derived from services provided by local ecosystems. Trade-offs resulting from changes in ecosystem services provision and associated impacts on livelihoods are also often overlooked. This paper proposes an innovative application of Bayesian belief networks - influence diagrams - as a decision support system for mediating trade-offs arising from the development of shrimp aquaculture in Thailand. Senior experts were consulted (n = 12) and primary farm data on the economics of shrimp farming (n = 20) were collected alongside secondary information on ecosystem services, in order to construct and populate the network. Trade-offs were quantitatively assessed through the generation of a probabilistic impact matrix. This matrix captures nonlinearity and uncertainty and describes the relative performance and impacts of shrimp farming management scenarios on local livelihoods. It also incorporates export revenues and provision and value of ecosystem services such as coastal protection and biodiversity. This research shows that Bayesian belief modeling can support complex decision-making on pathways for sustainable coastal aquaculture development and thus contributes to the debate on the role of aquaculture in social-ecological resilience and economic development.

  14. Capturing ecosystem services, stakeholders' preferences and trade-offs in coastal aquaculture decisions: a Bayesian belief network application.

    Directory of Open Access Journals (Sweden)

    Laetitia Helene Marie Schmitt

    Full Text Available Aquaculture activities are embedded in complex social-ecological systems. However, aquaculture development decisions have tended to be driven by revenue generation, failing to account for interactions with the environment and the full value of the benefits derived from services provided by local ecosystems. Trade-offs resulting from changes in ecosystem services provision and associated impacts on livelihoods are also often overlooked. This paper proposes an innovative application of Bayesian belief networks - influence diagrams - as a decision support system for mediating trade-offs arising from the development of shrimp aquaculture in Thailand. Senior experts were consulted (n = 12 and primary farm data on the economics of shrimp farming (n = 20 were collected alongside secondary information on ecosystem services, in order to construct and populate the network. Trade-offs were quantitatively assessed through the generation of a probabilistic impact matrix. This matrix captures nonlinearity and uncertainty and describes the relative performance and impacts of shrimp farming management scenarios on local livelihoods. It also incorporates export revenues and provision and value of ecosystem services such as coastal protection and biodiversity. This research shows that Bayesian belief modeling can support complex decision-making on pathways for sustainable coastal aquaculture development and thus contributes to the debate on the role of aquaculture in social-ecological resilience and economic development.

  15. A Decision Support System for Assessing Trade-Offs between Ecosystem Management Goals: An Application in Portugal

    Directory of Open Access Journals (Sweden)

    Jordi Garcia-Gonzalo

    2014-12-01

    Full Text Available Cork oak (Quercus suber L. and holm oak (Quercus rotundifolia ecosystems are characteristic of Mediterranean forestry in Portugal. Even though cork is the most valuable product, these ecosystems provide multiple products and services. Assessing trade-offs between multiple goals is thus critical for the effectiveness of oak ecosystem management planning. This paper focuses on the development of a decision support system for oak ecosystems’ scenario analysis including multiple criteria. It includes an innovative decision support systems (DSS functionality to assess trade-offs between the criteria that may support negotiation and consensus building between decision-makers and forest stakeholders. Specifically, a module that encapsulates the Feasible Goals Method/Interactive Decision Maps (FGM/IDM technique is developed for interactive visualization of the Pareto frontier. The Pareto frontier illustrates the degree to which improving one particular criterion requires accepting sacrifices in the achievements of others. It thus provides information about trade-offs between competing decision-makers’ preferences. Results are discussed for a large-scale application encompassing over 1 million ha of cork and holm oak forest ecosystems in Southern Portugal. This study demonstrates the potential of the new DSS functionality to enhance multi-objective forest planning, namely by facilitating participation by stakeholders and providing transparency to the decision-making processes.

  16. Trade-offs between reproductive allocation and storage in species of Oenothera L. (Onagraceae) native to Argentina

    Science.gov (United States)

    Vilela, Alejandra; Cariaga, Rodrigo; González-Paleo, Luciana; Ravetta, Damián

    2008-01-01

    A trade-off between reproduction and survival arises because current reproduction diminishes levels of a limiting resource such that less can be placed in storage organs for the survival of an organism during the unfavorable season. Oenothera is a particularly suited genus for studying those kind of trade-offs because it contains species with different life-history strategies (annual, biennial and perennial). Since allocation to leaves is a major factor associated with changes in life-history, here we tested the hypothesis that Oenothera leaf attributes would affect plant reproductive effort and therefore, root reserves. We selected two groups of taxa differing in their leaf area ratio (low- and high-LAR) and we compared their pattern of resource allocation to growth, reproduction and storage. Path analysis confirmed our hypothesis that LAR is the most important variable in explaining variation in allocation to reproduction or storage. The group with high allocation to leaves assigned resources preferentially to storage while the other group allocated more resources to reproduction, as predicted. A trade-off between reproduction and storage was only confirmed for the high-LAR group. The low-LAR group showed the life-history tactic of annual plants, while the high-LAR group exhibited a strategy generally associated with perenniality.

  17. Trade-offs in osmoregulation and parallel shifts in molecular function follow ecological transitions to freshwater in the Alewife.

    Science.gov (United States)

    Velotta, Jonathan P; McCormick, Stephen D; Schultz, Eric T

    2015-10-01

    Adaptation to freshwater may be expected to reduce performance in seawater because these environments represent opposing selective regimes. We tested for such a trade-off in populations of the Alewife (Alosa pseudoharengus). Alewives are ancestrally anadromous, and multiple populations have been independently restricted to freshwater (landlocked). We conducted salinity challenge experiments, whereby juvenile Alewives from one anadromous and multiple landlocked populations were exposed to freshwater and seawater on acute and acclimation timescales. In response to acute salinity challenge trials, independently derived landlocked populations varied in the degree to which seawater tolerance has been lost. In laboratory-acclimation experiments, landlocked Alewives exhibited improved freshwater tolerance, which was correlated with reductions in seawater tolerance and hypo-osmotic balance, suggesting that trade-offs in osmoregulation may be associated with local adaptation to freshwater. We detected differentiation between life-history forms in the expression of an ion-uptake gene (NHE3), and in gill Na(+) /K(+) -ATPase activity. Trade-offs in osmoregulation, therefore, may be mediated by differentiation in ion-uptake and salt-secreting pathways. PMID:26374626

  18. Supply-demand equilibria and the size-number trade-off in spatially structured recreational fisheries.

    Science.gov (United States)

    Wilson, Kyle L; Cantin, Ariane; Ward, Hillary G M; Newton, Eric R; Mee, Jonathan A; Varkey, Divya A; Parkinson, Eric A; Post, John R

    2016-06-01

    Recreational fishing effort varies across complex inland landscapes (e.g., lake-districts) and appears influenced by both angler preferences and qualities of the fishery resource, like fish size and abundance. However, fish size and abundance have an ecological trade-off within a population, thereby structuring equal-quality isopleths expressing this trade-off across the fishing landscape. Since expressed preferences of recreational anglers (i.e., site-selection of high-quality fishing opportunities among many lakes) can be analogous to optimal foraging strategies of natural predators, adopting such concepts can aid in understanding scale-dependence in fish-angler interactions and impacts of fishing across broad landscapes. Here, we assumed a fish supply-angler demand equilibria and adapted a novel bivariate measure of fishing quality based on fish size and catch rates to assess how recreational anglers influence fishing quality among a complex inland landscape. We then applied this metric to evaluate (1) angler preferences for caught and released fish compared to harvested fish, (2) the nonlinear size-numbers trade-off with uncertainty in both traits, and (3) the spatial-scale of the equilibria across 62 lakes and four independent management regions in British Columbia's (BC) rainbow trout Oncorhynchus mykiss fishery. We found anglers had low preference for caught and released fish (~10% of the value compared to harvested fish), which modified anglers' perception of fishing quality. Hence, fishing quality and angler effort was not influenced simply by total fish caught, but largely by harvested fish catch rates. Fishing quality varied from BC's northern regions (larger fish and more abundant) compared to southern regions (smaller fish and less abundant) directly associated with a 2.5 times increase in annual fishing effort in southern regions, suggesting that latent fishing pressure can structure the size-numbers trade-off in rainbow trout populations. The

  19. Supply-demand equilibria and the size-number trade-off in spatially structured recreational fisheries.

    Science.gov (United States)

    Wilson, Kyle L; Cantin, Ariane; Ward, Hillary G M; Newton, Eric R; Mee, Jonathan A; Varkey, Divya A; Parkinson, Eric A; Post, John R

    2016-06-01

    Recreational fishing effort varies across complex inland landscapes (e.g., lake-districts) and appears influenced by both angler preferences and qualities of the fishery resource, like fish size and abundance. However, fish size and abundance have an ecological trade-off within a population, thereby structuring equal-quality isopleths expressing this trade-off across the fishing landscape. Since expressed preferences of recreational anglers (i.e., site-selection of high-quality fishing opportunities among many lakes) can be analogous to optimal foraging strategies of natural predators, adopting such concepts can aid in understanding scale-dependence in fish-angler interactions and impacts of fishing across broad landscapes. Here, we assumed a fish supply-angler demand equilibria and adapted a novel bivariate measure of fishing quality based on fish size and catch rates to assess how recreational anglers influence fishing quality among a complex inland landscape. We then applied this metric to evaluate (1) angler preferences for caught and released fish compared to harvested fish, (2) the nonlinear size-numbers trade-off with uncertainty in both traits, and (3) the spatial-scale of the equilibria across 62 lakes and four independent management regions in British Columbia's (BC) rainbow trout Oncorhynchus mykiss fishery. We found anglers had low preference for caught and released fish (~10% of the value compared to harvested fish), which modified anglers' perception of fishing quality. Hence, fishing quality and angler effort was not influenced simply by total fish caught, but largely by harvested fish catch rates. Fishing quality varied from BC's northern regions (larger fish and more abundant) compared to southern regions (smaller fish and less abundant) directly associated with a 2.5 times increase in annual fishing effort in southern regions, suggesting that latent fishing pressure can structure the size-numbers trade-off in rainbow trout populations. The

  20. The value trade-off in higher education service: A qualitative intercultural approach to students’ perceptions

    Directory of Open Access Journals (Sweden)

    Danni Li

    2016-08-01

    Full Text Available Purpose: Higher Education Institutions have become a highly competitive market, where consumers (i.e. students are highly involved in their choices, and managers need to focus on competitive edges. This paper aims to understand the factors that influence student choice behaviour and fulfil student expectations of customer value in higher education institutions (HEIs. Design/methodology/approach: with qualitative information (focus groups collected from international students of several universities in Spain, Britain and China, the paper investigates the formation of customer value, as a trade-off between benefits and costs. This qualitative approach aims first at assessing this particular service through the concept of value through verifying both the positive and negative dimensions of HE, and second, to comment on the intercultural aspects of this dual approach to higher education consumption. Findings: the results show different levels of benefits: the functional value generally comes from infrastructures and good teachers that offer abundant practical experiences. The benefits from quality education also derived from teamwork with the colleagues who possess equal academic strength. Social benefits come from experiences outside the academic environment, working with people from different cultural backgrounds who have different perspectives. Emotional rewards come from University reputation and relationships with instructors. Costs of time and effort are differently seen across programs and vary widely upon nationalities and cultural backgrounds. Practical implications: since the competitive environments are fast becoming more and more complex added to the fact that it changes rapidly and dynamically, to concentrate on a few key elements are most important to the organizations survival. Different values of customers in different countries suggest that the strategy used by the corporation in a certain country, may not be apply to another

  1. A trade-off between model resolution and variance with selected Rayleigh-wave data

    Science.gov (United States)

    Xia, J.; Miller, R.D.; Xu, Y.

    2008-01-01

    Inversion of multimode surface-wave data is of increasing interest in the near-surface geophysics community. For a given near-surface geophysical problem, it is essential to understand how well the data, calculated according to a layered-earth model, might match the observed data. A data-resolution matrix is a function of the data kernel (determined by a geophysical model and a priori information applied to the problem), not the data. A data-resolution matrix of high-frequency (??? 2 Hz) Rayleigh-wave phase velocities, therefore, offers a quantitative tool for designing field surveys and predicting the match between calculated and observed data. First, we employed a data-resolution matrix to select data that would be well predicted and to explain advantages of incorporating higher modes in inversion. The resulting discussion using the data-resolution matrix provides insight into the process of inverting Rayleigh-wave phase velocities with higher mode data to estimate S-wave velocity structure. Discussion also suggested that each near-surface geophysical target can only be resolved using Rayleigh-wave phase velocities within specific frequency ranges, and higher mode data are normally more accurately predicted than fundamental mode data because of restrictions on the data kernel for the inversion system. Second, we obtained an optimal damping vector in a vicinity of an inverted model by the singular value decomposition of a trade-off function of model resolution and variance. In the end of the paper, we used a real-world example to demonstrate that selected data with the data-resolution matrix can provide better inversion results and to explain with the data-resolution matrix why incorporating higher mode data in inversion can provide better results. We also calculated model-resolution matrices of these examples to show the potential of increasing model resolution with selected surface-wave data. With the optimal damping vector, we can improve and assess an inverted

  2. Cereal straw management: a trade-off between energy and agronomic fate

    Directory of Open Access Journals (Sweden)

    Massimo Monteleone

    2015-06-01

    experimental conditions. By selecting the best agricultural practices, energy from straw can be optimally coupled with grain productions, without detrimental effects on soil fertility. An improved and specifically tailored cropping system is designed to obtain an optimal trade-off.

  3. Trade-offs and mixed infections in an obligate-killing insect pathogen.

    Science.gov (United States)

    Redman, Elizabeth M; Wilson, Kenneth; Cory, Jenny S

    2016-09-01

    Natural populations of pathogens are frequently composed of numerous interacting strains. Understanding what maintains this diversity remains a key focus of research in disease ecology. In addition, within-host pathogen dynamics can have a strong impact on both infection outcome and the evolution of pathogen virulence, and thus, understanding the impact of pathogen diversity is important for disease management. We compared eight genetically distinguishable variants from Spodoptera exempta nucleopolyhedrovirus (SpexNPV) isolated from the African armyworm, Spodoptera exempta. NPVs are obligate killers, and the vast majority of transmission stages are not released until after the host has died. The NPV variants differed significantly in their virulence and could be clustered into two groups based on their dose-response curves. They also differed in their speed of kill and productivity (transmission potential) for S. exempta. The mixed-genotype wild-type (WT) SpexNPV, from which each variant was isolated, was significantly more virulent than any individual variant and its mean mortality rate was within the fastest group of individual variants. However, the WT virus produced fewer new infectious stages than any single variant, which might reflect competition among the variants. A survival analysis, combining the mortality and speed of kill data, confirmed the superiority of the genetically mixed WT virus over any single variant. Spodoptera exempta larvae infected with WT SpexNPV were predicted to die 2·7 and 1·9 times faster than insects infected with isolates from either of the two clusters of genotypes. Theory suggests that there are likely to be trade-offs between pathogen fitness traits. Across all larvae, there was a negative linear relationship between virus yield and speed of kill, such that more rapid host death carried the cost of producing fewer transmission stages. We also found a near-significant relationship for the same trend at the intervariant level

  4. Shared influence of pathogen and host genetics on a trade-off between latent period and spore production capacity in the wheat pathogen, Puccinia triticina

    OpenAIRE

    Pariaud, Benedicte; van den Berg, , F.; van den Bosch,; Powers, , S. J.; Kaltz, O.; Lannou, Christian

    2012-01-01

    Crop pathogens are notorious for their rapid adaptation to their host. We still know little about the evolution of their life cycles and whether there might be trade-offs between fitness components, limiting the evolutionary potential of these pathogens. In this study, we explored a trade-off between spore production capacity and latent period in Puccinia triticina, a fungal pathogen causing leaf rust on wheat. Using a simple multivariate (manova) technique, we showed that the covariance betw...

  5. Offspring pay sooner, parents pay later: experimental manipulation of body mass reveals trade-offs between immune function, reproduction and survival

    OpenAIRE

    Hegemann, A.; Matson, K.D.; Flinks, H.; Tieleman, B.I.

    2013-01-01

    Introduction - Life-history theory predicts that organisms trade off survival against reproduction. However, the time scales on which various consequences become evident and the physiology mediating the cost of reproduction remain poorly understood. Yet, explaining not only which mechanisms mediate this trade-off, but also how fast or slow the mechanisms act, is crucial for an improved understanding of life-history evolution. We investigated three time scales on which an experimental increase...

  6. Live fast die young life history in females: evolutionary trade-off between early life mating and lifespan in female Drosophila melanogaster

    OpenAIRE

    Travers, Laura M.; Francisco Garcia-Gonzalez; Simmons, Leigh W.

    2015-01-01

    The trade-off between survival and reproduction is fundamental to life history theory. Sexual selection is expected to favour a ‘live fast die young’ life history pattern in males due to increased risk of extrinsic mortality associated with obtaining mates. Sexual conflict may also drive a genetic trade-off between reproduction and lifespan in females. We found significant additive genetic variance in longevity independent of lifetime mating frequency, and in early life mating frequency. Ther...

  7. Context-dependent effects of parental effort on malaria infection in a wild bird population, and their role in reproductive trade-offs.

    Science.gov (United States)

    Knowles, Sarah C L; Wood, Matthew J; Sheldon, Ben C

    2010-09-01

    Although trade-offs between reproductive effort and other fitness components are frequently documented in wild populations, the underlying physiological mechanisms remain poorly understood. Parasitism has been suggested to mediate reproductive trade-offs, yet only a limited number of parasite taxa have been studied, and reproductive effort-induced changes in parasitism are rarely linked to trade-offs observed in the same population. We conducted a brood size manipulation experiment in blue tits (Cyanistes caeruleus) infected with malaria (Plasmodium) parasites, and used quantitative PCR to measure changes in parasitaemia. In one of two years investigated, parasitaemia increased as a result of brood enlargement, and was also positively associated with two other indicators of reproductive effort: clutch size and single parenthood. These associations between both experimental and naturally varying reproductive effort and parasitaemia suggest that immune control of chronic malaria infections can be compromised when parents are working hard. Brood size manipulation significantly affected the number of independent offspring produced, which was maximised when brood size was unchanged. Moreover, when parents were infected with one of two common Plasmodium species, the shape of this trade-off curve was more pronounced, suggesting that parasitic infection may exacerbate the trade-off between quantity and quality of offspring. Although the involvement of parasites in survival costs of reproduction has received much attention, these results suggest their role in other commonly documented reproductive trade-offs, such as that between number and quality of offspring, warrants further study. PMID:20625768

  8. Local orientation and the evolution of foraging: changes in decision making can eliminate evolutionary trade-offs.

    Directory of Open Access Journals (Sweden)

    Daniel J van der Post

    2011-10-01

    Full Text Available Information processing is a major aspect of the evolution of animal behavior. In foraging, responsiveness to local feeding opportunities can generate patterns of behavior which reflect or "recognize patterns" in the environment beyond the perception of individuals. Theory on the evolution of behavior generally neglects such opportunity-based adaptation. Using a spatial individual-based model we study the role of opportunity-based adaptation in the evolution of foraging, and how it depends on local decision making. We compare two model variants which differ in the individual decision making that can evolve (restricted and extended model, and study the evolution of simple foraging behavior in environments where food is distributed either uniformly or in patches. We find that opportunity-based adaptation and the pattern recognition it generates, plays an important role in foraging success, particularly in patchy environments where one of the main challenges is "staying in patches". In the restricted model this is achieved by genetic adaptation of move and search behavior, in light of a trade-off on within- and between-patch behavior. In the extended model this trade-off does not arise because decision making capabilities allow for differentiated behavioral patterns. As a consequence, it becomes possible for properties of movement to be specialized for detection of patches with more food, a larger scale information processing not present in the restricted model. Our results show that changes in decision making abilities can alter what kinds of pattern recognition are possible, eliminate an evolutionary trade-off and change the adaptive landscape.

  9. Haste makes waste but condition matters: molt rate-feather quality trade-off in a sedentary songbird.

    Directory of Open Access Journals (Sweden)

    Csongor I Vágási

    Full Text Available BACKGROUND: The trade-off between current and residual reproductive values is central to life history theory, although the possible mechanisms underlying this trade-off are largely unknown. The 'molt constraint' hypothesis suggests that molt and plumage functionality are compromised by the preceding breeding event, yet this candidate mechanism remains insufficiently explored. METHODOLOGY/PRINCIPAL FINDINGS: The seasonal change in photoperiod was manipulated to accelerate the molt rate. This treatment simulates the case of naturally late-breeding birds. House sparrows Passer domesticus experiencing accelerated molt developed shorter flight feathers with more fault bars and body feathers with supposedly lower insulation capacity (i.e. shorter, smaller, with a higher barbule density and fewer plumulaceous barbs. However, the wing, tail and primary feather lengths were shorter in fast-molting birds if they had an inferior body condition, which has been largely overlooked in previous studies. The rachis width of flight feathers was not affected by the treatment, but it was still condition-dependent. CONCLUSIONS/SIGNIFICANCE: This study shows that sedentary birds might face evolutionary costs because of the molt rate-feather quality conflict. This is the first study to experimentally demonstrate that (1 molt rate affects several aspects of body feathers as well as flight feathers and (2 the costly effects of rapid molt are condition-specific. We conclude that molt rate and its association with feather quality might be a major mediator of life history trade-offs. Our findings also suggest a novel advantage of early breeding, i.e. the facilitation of slower molt and the condition-dependent regulation of feather growth.

  10. Water deficit induces swainsonine of some locoweed taxa, but with no swainsonine-growth trade-off

    Science.gov (United States)

    Vallotton, Amber D.; Murray, Leigh W.; Delaney, Kevin J.; Sterling, Tracy M.

    2012-08-01

    Environmental factors like nutrient availability (e.g., C:N) and water deficit can influence secondary metabolites levels in plants and fungal endophytes. Locoweeds (Astragalus and Oxytropis spp.) contain swainsonine (SWA), an alkaloid that causes chronic vertebrate toxicity. In two greenhouse experiments, we studied field transplants of three Astragalus mollissimus varieties that vary in SWA levels (barely detectable SWA in var. 'thompsonae', intermediate SWA in var. 'bigelovii', and high SWA in var. 'mollissimus'), and intermediate SWA in Oxytropis sericea; our results confirmed these rankings. We tested whether SWA induction after water deficit (three 14d water-deficit periods separated by two 7d water recovery periods) was taxon-specific and whether degree of induction was influenced by taxon average SWA. We also looked for signs of a trade-off between primary physiology (photosynthesis) or growth (biomass, relative growth rate) with fungal endophyte SWA production; and if so, whether water stress magnified such a trade-off. Leaf photosynthetic activity decreased during the experiments and often more in water-deficit than control plants; leaf gs and Ci results suggest that stomatal closure reduced photosynthetic activity from mild water deficit. Yet, water-deficit affected plants in other ways: there were more dropped senesced leaves for all tested taxa; higher water-use efficiency for var. mollissimus, var. thompsonae, and O. sericea; higher root mass ratios for var. bigelovii, var. thompsonae, and O. sericea; and lower relative water content for var. thompsonae. Positive SWA increases of 1.6-fold for var. mollissimus and 4-fold for var. bigelovii occurred, so positive SWA induction was taxon-specific and limited to medium/high SWA A. mollissimus varieties. There was little evidence for a clear SWA trade-off with total (shoot + root) biomass, relative growth rate, or photosynthetic rate. Additional studies will need to test whether water deficit positively

  11. An apparent trade-off between direct and signal-based induced indirect defence against herbivores in willow trees.

    Directory of Open Access Journals (Sweden)

    Kinuyo Yoneya

    Full Text Available Signal-based induced indirect defence refers to herbivore-induced production of plant volatiles that attract carnivorous natural enemies of herbivores. Relationships between direct and indirect defence strategies were studied using tritrophic systems consisting of six sympatric willow species, willow leaf beetles (Plagiodera versicolora, and their natural predators, ladybeetles (Aiolocaria hexaspilota. Relative preferences of ladybeetles for prey-infested willow plant volatiles, indicating levels of signal-based induced indirect defence, were positively correlated with the vulnerability of willow species to leaf beetles, assigned as relative levels of direct defence. This correlation suggested a possible trade-off among the species, in terms of resource limitation between direct defence and signal-based induced indirect defence. However, analyses of volatiles from infested and uninfested plants showed that the specificity of infested volatile blends (an important factor determining the costs of signal-based induced indirect defence did not affect the attractiveness of infested plant volatiles. Thus, the suggested trade-off in resource limitation was unlikely. Rather, principal coordinates analysis showed that this 'apparent trade-off' between direct and signal-based induced indirect defence was partially explained by differential preferences of ladybeetles to infested plant volatiles of the six willow species. We also showed that relative preferences of ladybeetles for prey-infested willow plant volatiles were positively correlated with oviposition preferences of leaf beetles and with the distributions of leaf beetles in the field. These correlations suggest that ladybeetles use the specificity of infested willow plant volatiles to find suitable prey patches.

  12. Experimentally decoupling reproductive investment from energy storage to test the functional basis of a life-history trade-off.

    Science.gov (United States)

    Cox, Robert M; Lovern, Matthew B; Calsbeek, Ryan

    2014-07-01

    The ubiquitous life-history trade-off between reproduction and survival has long been hypothesized to reflect underlying energy-allocation trade-offs between reproductive investment and processes related to self-maintenance. Although recent work has questioned whether energy-allocation models provide sufficient explanations for the survival cost of reproduction, direct tests of this hypothesis are rare, especially in wild populations. This hypothesis was tested in a wild population of brown anole lizards (Anolis sagrei) using a two-step experiment. First, stepwise variation in reproductive investment was created using unilateral and bilateral ovariectomy (OVX) along with intact (SHAM) control. Next, this manipulation was decoupled from its downstream effects on energy storage by surgically ablating the abdominal fat stores from half of the females in each reproductive treatment. As predicted, unilateral OVX (intermediate reproductive investment) induced levels of growth, body condition, fat storage and breeding-season survival that were intermediate between the high levels of bilateral OVX (no reproductive investment) and the low levels of SHAM (full reproductive investment). Ablation of abdominal fat bodies had a strong and persistent effect on energy stores, but it did not influence post-breeding survival in any of the three reproductive treatments. This suggests that the energetic savings of reduced reproductive investment do not directly enhance post-breeding survival, with the caveat that only one aspect of energy storage was manipulated and OVX itself had no overall effect on post-breeding survival. This study supports the emerging view that simple energy-allocation models may often be insufficient as explanations for the life-history trade-off between reproduction and survival.

  13. A hybrid input–output multi-objective model to assess economic–energy–environment trade-offs in Brazil

    International Nuclear Information System (INIS)

    A multi-objective linear programming (MOLP) model based on a hybrid Input–Output (IO) framework is presented. This model aims at assessing the trade-offs between economic, energy, environmental (E3) and social objectives in the Brazilian economic system. This combination of multi-objective models with Input–Output Analysis (IOA) plays a supplementary role in understanding the interactions between the economic and energy systems, and the corresponding impacts on the environment, offering a consistent framework for assessing the effects of distinct policies on these systems. Firstly, the System of National Accounts (SNA) is reorganized to include the National Energy Balance, creating a hybrid IO framework that is extended to assess Greenhouse Gas (GHG) emissions and the employment level. The objective functions considered are the maximization of GDP (gross domestic product) and employment levels, as well as the minimization of energy consumption and GHG emissions. An interactive method enabling a progressive and selective search of non-dominated solutions with distinct characteristics and underlying trade-offs is utilized. Illustrative results indicate that the maximization of GDP and the employment levels lead to an increase of both energy consumption and GHG emissions, while the minimization of either GHG emissions or energy consumption cause negative impacts on GDP and employment. - Highlights: • A hybrid Input–Output multi-objective model is applied to the Brazilian economy. • Objective functions are GDP, employment level, energy consumption and GHG emissions. • Interactive search process identifies trade-offs between the competing objectives. • Positive correlations between GDP growth and employment. • Positive correlations between energy consumption and GHG emissions

  14. Testing phenotypic trade-offs in the chemical defence strategy of Scots pine under growth-limiting field conditions.

    Science.gov (United States)

    Villari, Caterina; Faccoli, Massimo; Battisti, Andrea; Bonello, Pierluigi; Marini, Lorenzo

    2014-09-01

    Plants protect themselves from pathogens and herbivores through fine-tuned resource allocation, including trade-offs among resource investments to support constitutive and inducible defences. However, empirical research, especially concerning conifers growing under natural conditions, is still scarce. We investigated the complexity of constitutive and induced defences in a natural Scots pine (Pinus sylvestris L.) stand under growth-limiting conditions typical of alpine environments. Phenotypic trade-offs at three hierarchical levels were tested by investigating the behaviour of phenolic compounds and terpenoids of outer bark and phloem. We tested resource-derived phenotypic correlations between (i) constitutive and inducible defences vs tree ring growth, (ii) different constitutive defence metabolites and (iii) constitutive concentration and inducible variation of individual metabolites. Tree ring growth was positively correlated only with constitutive concentration of total terpenoids, and no overall phenotypic trade-offs between different constitutive defensive metabolites were found. At the lowest hierarchical level tested, i.e., at the level of relationship between constitutive and inducible variation of individual metabolites, we found that different compounds displayed different behaviours; we identified five different defensive metabolite response types, based on direction and strength of the response, regardless of tree age and growth rate. Therefore, under growth-limiting field conditions, Scots pine appears to utilize varied and complex outer bark and phloem defence chemistry, in which only part of the constitutive specialized metabolism is influenced by tree growth, and individual components do not appear to be expressed in a mutually exclusive manner in either constitutive or inducible metabolism.

  15. Ecosystem-scale trade-offs between impacts of ozone and reactive nitrogen

    Science.gov (United States)

    Rowe, Ed; Hayes, Felicity; Sawicka, Kasia; Mills, Gina; Jones, Laurence; Moldan, Filip; Sereina, Bassin; van Dijk, Netty; Evans, Chris

    2015-04-01

    Nitrogen (N) deposition stimulates plant productivity in many terrestrial ecosystems. This is clearly beneficial for production agriculture and forestry, but increased litterfall and decreased ground-level light availability reduce the suitability of habitats for many biota (Jones et al., 2014). This mechanism (Hautier et al., 2009), together with the acidifying effects of N (Stevens et al., 2010), has caused considerable biodiversity loss at global scale. Ozone, by contrast, has the effect of reducing plant production, and a simple assessment would suggest that this might mitigate the effects of N pollution. We explored the interactions between ozone and nitrogen at mechanistic level using a version of the MADOC model (Rowe et al., 2014) modified to include effects of ozone. The model was tested against data from long-term monitoring and experimental sites with a focus on nitrogen and/or ozone effects. Effects on biodiversity were assessed by coupling the MADOC model to the MultiMOVE plant species model. We used this model-chain to explore trade-offs and synergies between the impacts of nitrogen and ozone on biodiversity and ecosystem biogeochemistry. In a review of the effects of ozone on ecosystem processes, two consistent effects were found: decreased net primary production due to damage to photosynthetic mechanisms; and an increase in litter nitrogen apparently caused by interference of ozone with the retranslocation process (Mills, in prep.). Insufficient evidence was found to justify inclusion of posited interactive mechanisms such as increased ozone susceptibility with greater nitrogen supply. However, the MADOC model illustrated emergent ozone-nitrogen interactions at ecosystem scale, for example an increase in N leaching due to decreased plant demand and greater litter N content. Empirical evidence for interactive effects of nitrogen and ozone at ecosystem scale is severely lacking, but simulated results were consistent with soil and soil solution

  16. Modelling and interpreting fish bioenergetics: a role for behaviour, life-history traits and survival trade-offs

    Science.gov (United States)

    Jørgensen, C; Enberg, K; Mangel, M

    2016-01-01

    Bioenergetics is used as the mechanistic foundation of many models of fishes. As the context of a model gradually extends beyond pure bioenergetics to include behaviour, life-history traits and function and performance of the entire organism, so does the need for complementing bioenergetic measurements with trade-offs, particularly those dealing with survival. Such a broadening of focus revitalized and expanded the domain of behavioural ecology in the 1980s. This review makes the case that a similar change of perspective is required for physiology to contribute to the types of predictions society currently demands, e.g. regarding climate change and other anthropogenic stressors. PMID:26768979

  17. Trade-Off between Collusion Resistance and User Life Cycle in Self-Healing Key Distributions with t-Revocation

    OpenAIRE

    Dutta, Ratna; Dowling, Tom; Mukhopadhyay, Sourav

    2009-01-01

    We solve the problem of resisting the collusion attack in the one-way hash chain based self-healing key distributions introduced by Dutta et al., coupling it with the prearranged life cycle based approach of Tian et al. that uses the same self-healing mechanism introduced in Dutta et al. Highly efficient schemes are developed compared to the existing works with the trade-off in pre-arranged life cycles on users by the group manager and a slight increase in the storage overhead. For scalabi...

  18. Trade-offs Between Electricity Production from Small Hydropower Plants and Ecosystem Services in Alpine River Basins

    Science.gov (United States)

    Meier, Philipp; Schwemmle, Robin; Viviroli, Daniel

    2015-04-01

    The need for a reduction in greenhouse gas emissions and the decision to phase out nuclear power plants in Switzerland and Germany increases pressure to develop the remaining hydropower potential in Alpine catchments. Since most of the potential for large reservoirs is already exploited, future development focusses on small run-of-the-river hydropower plants (SHP). Being considered a relatively environment-friendly electricity source, investment in SHP is promoted through subsidies. However, SHP can have a significant impact on riverine ecosystems, especially in the Alpine region where residual flow reaches tend to be long. An increase in hydropower exploitation will therefore increase pressure on ecosystems. While a number of studies assessed the potential for hydropower development in the Alps, two main factors were so far not assessed in detail: (i) ecological impacts within a whole river network, and (ii) economic conditions under which electricity is sold. We present a framework that establishes trade-offs between multiple objectives regarding environmental impacts, electricity production and economic evaluation. While it is inevitable that some ecosystems are compromised by hydropower plants, the context of these impacts within a river network should be considered when selecting suitable sites for SHP. From an ecological point of view, the diversity of habitats, and therefore the diversity of species, should be maintained within a river basin. This asks for objectives that go beyond lumped parameters of hydrological alteration, but also consider habitat diversity and the spatial configuration. Energy production in run-of-the-river power plants depends on available discharge, which can have large fluctuations. In a deregulated electricity market with strong price variations, an economic valuation should therefore be based on the expected market value of energy produced. Trade-off curves between different objectives can help decision makers to define policies

  19. Developing an integrated concept for the E-ELT Multi-Object Spectrograph (MOSAIC): design issues and trade-offs

    CERN Document Server

    Rodrigues, Myriam; Fitzsimons, Ewan; Chemla, Fanny; Morris, Tim; Hammer, Francois; Puech, Mathieu; Evans, Christopher; Jagourel, Pascal

    2016-01-01

    We present a discussion of the design issues and trade-offs that have been considered in putting together a new concept for MOSAIC, the multi-object spectrograph for the E-ELT. MOSAIC aims to address the combined science cases for E-ELT MOS that arose from the earlier studies of the multi-object and multi-adaptive optics instruments. MOSAIC combines the advantages of a highly-multiplexed instrument targeting single-point objects with one which has a more modest multiplex but can spatially resolve a source with high resolution (IFU). These will span across two wavebands: visible and near-infrared.

  20. Food-Carbon Trade-offs between Agriculture and Reforestation Land Uses under Alternate Market-based Policies

    OpenAIRE

    Brett Anthony. Bryan; Stacey Paterson

    2012-01-01

    Understanding the effects of payments on the adoption of reforestation in agricultural areas and the associated food-carbon trade-offs is necessary to inform climate change policy. Economic viability of reforestation under payment per hectare and payment per tonne schemes for carbon sequestration was assessed in a region in southern Australia supporting 6.1 Mha of rain-fed agriculture. The results show that under the median scenario, a carbon price of 27 A$/tCO2-e could make one-third of the ...

  1. Expanding comparative-advantage biological market models: contingency of mutualism on partners' resource requirements and acquisition trade-offs.

    Science.gov (United States)

    Hoeksema, Jason D; Schwartz, Mark W

    2003-05-01

    We expand the comparative-advantage biological market-modelling framework to show how differences between partners, both in their abilities to acquire two resources and in their requirements for those resources, can affect the net benefit of participating in interspecific resource exchange. In addition, the benefits derived from resource trading depend strongly on the nature of the trade-off between the acquisition of one resource and the acquisition of another, described here by the shape (linear, convex or concave) of the resource acquisition constraints of the individuals involved. Combined with previous results, these analyses provide a suite of predictions about whether or not resource exchange is beneficial for two heterospecific individuals relative to a strategy of non-interaction. The benefit derived from resource exchange depends on three factors: (i) relative differences between the partners in their resource acquisition abilities; (ii) relative differences between the partners in their resource requirements; and (iii) variation in the shape of resource acquisition trade-offs. We find that such an explicit consideration of resource requirements and acquisition abilities can provide useful and sometimes non-intuitive predictions about the benefits of resource exchange, and also which resources should be traded by which species.

  2. Optimal defense strategies in an idealized microbial food web under trade-off between competition and defense.

    Science.gov (United States)

    Våge, Selina; Storesund, Julia E; Giske, Jarl; Thingstad, T Frede

    2014-01-01

    Trophic mechanisms that can generate biodiversity in food webs include bottom-up (growth rate regulating) and top-down (biomass regulating) factors. The top-down control has traditionally been analyzed using the concepts of "Keystone Predation" (KP) and "Killing-the-Winner" (KtW), predominately occuring in discussions of macro- and micro-biological ecology, respectively. Here we combine the classical diamond-shaped food web structure frequently discussed in KP analyses and the KtW concept by introducing a defense strategist capable of partial defense. A formalized description of a trade-off between the defense-strategist's competitive and defensive ability is included. The analysis reveals a complex topology of the steady state solution with strong relationships between food web structure and the combination of trade-off, defense strategy and the system's nutrient content. Among the results is a difference in defense strategies corresponding to maximum biomass, production, or net growth rate of invading individuals. The analysis thus summons awareness that biomass or production, parameters typically measured in field studies to infer success of particular biota, are not directly acted upon by natural selection. Under coexistence with a competition specialist, a balance of competitive and defensive ability of the defense strategist was found to be evolutionarily stable, whereas stronger defense was optimal under increased nutrient levels in the absence of the pure competition specialist. The findings of success of different defense strategies are discussed with respect to SAR11, a highly successful bacterial clade in the pelagic ocean.

  3. Insight into trade-off between wood decay and parasitism from the genome of a fungal forest pathogen

    Energy Technology Data Exchange (ETDEWEB)

    Olson, Ake; Aerts, Andrea; Asiegbu, Fred; Belbahri, Lassaad; Bouzid, Ourdia; Broberg, Anders; Canback, Bjorn; Coutinho, Pedro M.; Cullen, Dan; Dalman, Kerstin; Deflorio, Giuliana; van Diepen, Linda T. A.; Dunand, Christophe; Duplessis, Sebastien; Durling, Mikael; Gonthier, Paolo; Grimwood, Jane; Fossdal, Carl Gunnar; Hansson, David; Henrissat, Bernard; Hietala, Ari; Himmelstrand, Kajsa; Hoffmeister, Dirk; Hogberg, Nils; James, Timothy Y.; Karlsson, Magnus; Kohler, Annegret; Lucas, Susan; Lunden, Karl; Morin, Emmanuelle; Murat, Claude; Park, Jongsun; Raffaello, Tommaso; Rouze, Pierre; Salamov, Asaf; Schmutz, Jeremy; Solheim, Halvor; Stahlberg, Jerry; Velez, Heriberto; de Vries, Ronald P.; Wiebenga, Ad; Woodward, Steve; Yakovlev, Igor; Garbelotto, Matteo; Martin, Francis; Grigoriev, Igor V.; Stenlid, Jan

    2012-01-01

    Parasitism and saprotrophic wood decay are two fungal strategies fundamental for succession and nutrient cycling in forest ecosystems. An opportunity to assess the trade-off between these strategies is provided by the forest pathogen and wood decayer Heterobasidion annosum sensu lato. We report the annotated genome sequence and transcript profiling, as well as the quantitative trait loci mapping, of one member of the species complex: H. irregulare. Quantitative trait loci critical for pathogenicity, and rich in transposable elements, orphan and secreted genes, were identified. A wide range of cellulose-degrading enzymes are expressed during wood decay. By contrast, pathogenic interaction between H. irregulare and pine engages fewer carbohydrate-active enzymes, but involves an increase in pectinolytic enzymes, transcription modules for oxidative stress and secondary metabolite production. Our results show a trade-off in terms of constrained carbohydrate decomposition and membrane transport capacity during interaction with living hosts. Our findings establish that saprotrophic wood decay and necrotrophic parasitism involve two distinct, yet overlapping, processes.

  4. Incest versus abstinence: reproductive trade-offs between mate limitation and progeny fitness in a self-incompatible invasive plant.

    Science.gov (United States)

    Pierson, Jennifer C; Swain, Stephen M; Young, Andrew G

    2013-12-01

    Plant mating systems represent an evolutionary and ecological trade-off between reproductive assurance through selfing and maximizing progeny fitness through outbreeding. However, many plants with sporophytic self-incompatibility systems exhibit dominance interactions at the S-locus that allow biparental inbreeding, thereby facilitating mating between individuals that share alleles at the S-locus. We investigated this trade-off by estimating mate availability and biparental inbreeding depression in wild radish from five different populations across Australia. We found dominance interactions among S-alleles increased mate availability relative to estimates based on individuals that did not share S-alleles. Twelve of the sixteen fitness variables were significantly reduced by inbreeding. For all the three life-history phases evaluated, self-fertilized offspring suffered a greater than 50% reduction in fitness, while full-sib and half-sib offspring suffered a less than 50% reduction in fitness. Theory indicates that fitness costs greater than 50% can result in an evolutionary trajectory toward a stable state of self-incompatibility (SI). This study suggests that dominance interactions at the S-locus provide a possible third stable state between SI and SC where biparental inbreeding increases mate availability with relatively minor fitness costs. This strategy allows weeds to establish in new environments while maintaining a functional SI system.

  5. Nutritional and non-nutritional food components modulate phenotypic variation but not physiological trade-offs in an insect

    Science.gov (United States)

    Pascacio-Villafán, Carlos; Williams, Trevor; Birke, Andrea; Aluja, Martín

    2016-01-01

    Our understanding of how food modulates animal phenotypes and mediate trade-offs between life-history traits has benefited greatly from the study of combinations of nutritional and non-nutritional food components, such as plant secondary metabolites. We used a fruit fly pest, Anastrepha ludens, to examine phenotypic variation across larval, pupal and adult stages as a function of larval food with varying nutrient balance and content of chlorogenic acid, a secondary metabolite. Larval insects that fed on carbohydrate-biased diets relative to protein exhibited longer larval and pupal developmental periods, were often heavier as pupae and resisted desiccation and starvation for longer periods in the adult stage than insects fed on highly protein-biased diets. Except for a potential conflict between pupal development time and adult desiccation and starvation resistance, we did not detect physiological trade-offs mediated by the nutritional balance in larval food. Chlorogenic acid affected A. ludens development in a concentration and nutrient-dependent manner. Nutrients and host plant secondary metabolites in the larval diet induced changes in A. ludens phenotype and could influence fruit fly ecological interactions. We provide a unique experimental and modelling approach useful in generating predictive models of life history traits in a variety of organisms. PMID:27406923

  6. Habitat Fragmentation Intensifies Trade-Offs between Biodiversity and Ecosystem Services in a Heathland Ecosystem in Southern England.

    Science.gov (United States)

    Cordingley, Justine E; Newton, Adrian C; Rose, Robert J; Clarke, Ralph T; Bullock, James M

    2015-01-01

    While habitat fragmentation represents a major threat to global biodiversity, its impacts on provision of ecosystem services are largely unknown. We analysed biodiversity value and provision of multiple ecosystem services in 110 fragments of lowland heathland ecosystems in southern England, in which vegetation dynamics have been monitored for over 30 years. Decreasing fragment size was found to be associated with a decrease in biodiversity and recreational values, but an increase in relative carbon storage, aesthetic value and timber value. The trade-off between either biodiversity or recreational values with the other ecosystem services therefore became more pronounced as heathland size decreased. This was attributed to a higher rate of woody succession in smaller heathland fragments over the past three decades, and contrasting values of different successional vegetation types for biodiversity and provision of ecosystem services. These results suggest that habitat fragmentation can reduce the potential for developing "win win" solutions that contribute to biodiversity conservation while also supporting socio-economic development. Approaches to multi-purpose management of fragmented landscapes should therefore consider the potential trade-offs in ecosystem services and biodiversity associated with fragmentation, in order to make an effective contribution to sustainable development.

  7. Growth against entropy in bacterial metabolism: the phenotypic trade-off behind empirical growth rate distributions in E. coli

    Science.gov (United States)

    De Martino, Daniele; Capuani, Fabrizio; De Martino, Andrea

    2016-06-01

    The solution space of genome-scale models of cellular metabolism provides a map between physically viable flux configurations and cellular metabolic phenotypes described, at the most basic level, by the corresponding growth rates. By sampling the solution space of E. coli's metabolic network, we show that empirical growth rate distributions recently obtained in experiments at single-cell resolution can be explained in terms of a trade-off between the higher fitness of fast-growing phenotypes and the higher entropy of slow-growing ones. Based on this, we propose a minimal model for the evolution of a large bacterial population that captures this trade-off. The scaling relationships observed in experiments encode, in such frameworks, for the same distance from the maximum achievable growth rate, the same degree of growth rate maximization, and/or the same rate of phenotypic change. Being grounded on genome-scale metabolic network reconstructions, these results allow for multiple implications and extensions in spite of the underlying conceptual simplicity.

  8. Three's a Crowd: Trade-Offs between Attracting Pollinators and Ant Bodyguards with Nectar Rewards in Turnera.

    Science.gov (United States)

    Dutton, Emily M; Luo, Elaine Y; Cembrowski, Adam R; Shore, Joel S; Frederickson, Megan E

    2016-07-01

    Many plants attract insect pollinators with floral nectar (FN) and ant "bodyguards" with extrafloral nectar (EFN). If nectar production is costly or physiologically linked across glands, investment in one mutualism may trade off with investment in the other. We confirmed that changes in FN and EFN availability alter pollination and ant defense mutualisms in a field population of Turnera ulmifolia. Plants with additional FN tended to produce more seeds, while plants with reduced EFN production experienced less florivory. We then mimicked the consumptive effects of mutualists by removing FN or EFN daily for 50 days in a full factorial design using three Turnera species (T. joelii, T. subulata, and T. ulmifolia) in a glasshouse experiment. For T. ulmifolia and T. subulata, but not T. joelii, removing either nectar reduced production of the other, showing for the first time that EFN and FN production can trade off. In T. subulata, increased investment in FN decreased seed set, suggesting that nectar production can have direct fitness costs. Through the linked expression of EFN and FN, floral visitors may negatively affect biotic defense, and extrafloral nectary visitors may negatively affect pollination. PMID:27322120

  9. Nutritional and non-nutritional food components modulate phenotypic variation but not physiological trade-offs in an insect.

    Science.gov (United States)

    Pascacio-Villafán, Carlos; Williams, Trevor; Birke, Andrea; Aluja, Martín

    2016-01-01

    Our understanding of how food modulates animal phenotypes and mediate trade-offs between life-history traits has benefited greatly from the study of combinations of nutritional and non-nutritional food components, such as plant secondary metabolites. We used a fruit fly pest, Anastrepha ludens, to examine phenotypic variation across larval, pupal and adult stages as a function of larval food with varying nutrient balance and content of chlorogenic acid, a secondary metabolite. Larval insects that fed on carbohydrate-biased diets relative to protein exhibited longer larval and pupal developmental periods, were often heavier as pupae and resisted desiccation and starvation for longer periods in the adult stage than insects fed on highly protein-biased diets. Except for a potential conflict between pupal development time and adult desiccation and starvation resistance, we did not detect physiological trade-offs mediated by the nutritional balance in larval food. Chlorogenic acid affected A. ludens development in a concentration and nutrient-dependent manner. Nutrients and host plant secondary metabolites in the larval diet induced changes in A. ludens phenotype and could influence fruit fly ecological interactions. We provide a unique experimental and modelling approach useful in generating predictive models of life history traits in a variety of organisms. PMID:27406923

  10. Spatial Bayesian belief networks as a planning decision tool for mapping ecosystem services trade-offs on forested landscapes.

    Science.gov (United States)

    Gonzalez-Redin, Julen; Luque, Sandra; Poggio, Laura; Smith, Ron; Gimona, Alessandro

    2016-01-01

    An integrated methodology, based on linking Bayesian belief networks (BBN) with GIS, is proposed for combining available evidence to help forest managers evaluate implications and trade-offs between forest production and conservation measures to preserve biodiversity in forested habitats. A Bayesian belief network is a probabilistic graphical model that represents variables and their dependencies through specifying probabilistic relationships. In spatially explicit decision problems where it is difficult to choose appropriate combinations of interventions, the proposed integration of a BBN with GIS helped to facilitate shared understanding of the human-landscape relationships, while fostering collective management that can be incorporated into landscape planning processes. Trades-offs become more and more relevant in these landscape contexts where the participation of many and varied stakeholder groups is indispensable. With these challenges in mind, our integrated approach incorporates GIS-based data with expert knowledge to consider two different land use interests - biodiversity value for conservation and timber production potential - with the focus on a complex mountain landscape in the French Alps. The spatial models produced provided different alternatives of suitable sites that can be used by policy makers in order to support conservation priorities while addressing management options. The approach provided provide a common reasoning language among different experts from different backgrounds while helped to identify spatially explicit conflictive areas. PMID:26597639

  11. No trade-off between learning speed and associative flexibility in bumblebees: a reversal learning test with multiple colonies.

    Directory of Open Access Journals (Sweden)

    Nigel E Raine

    Full Text Available Potential trade-offs between learning speed and memory-related performance could be important factors in the evolution of learning. Here, we test whether rapid learning interferes with the acquisition of new information using a reversal learning paradigm. Bumblebees (Bombus terrestris were trained to associate yellow with a floral reward. Subsequently the association between colour and reward was reversed, meaning bees then had to learn to visit blue flowers. We demonstrate that individuals that were fast to learn yellow as a predictor of reward were also quick to reverse this association. Furthermore, overnight memory retention tests suggest that faster learning individuals are also better at retaining previously learned information. There is also an effect of relatedness: colonies whose workers were fast to learn the association between yellow and reward also reversed this association rapidly. These results are inconsistent with a trade-off between learning speed and the reversal of a previously made association. On the contrary, they suggest that differences in learning performance and cognitive (behavioural flexibility could reflect more general differences in colony learning ability. Hence, this study provides additional evidence to support the idea that rapid learning and behavioural flexibility have adaptive value.

  12. Flowering schedule in a perennial plant; life-history trade-offs, seed predation, and total offspring fitness.

    Science.gov (United States)

    Ehrlén, Johan; Raabova, Jana; Dahlgren, Johan P

    2015-08-01

    Optimal timing of reproduction within a season may be influenced by several abiotic and biotic factors. These factors sometimes affect different components of fitness, making assessments of net selection difficult. We used estimates of offspring fitness to examine how pre-dispersal seed predation influences selection on flowering schedule in an herb with a bimodal flowering pattern, Actaea spicata. Within individuals, seeds from flowers on early terminal inflorescences had a higher germination rate and produced larger seedlings than seeds from flowers on late basal inflorescences. Reproductive value, estimated using demographic integral projection models and accounting for size-dependent differences in future performance, was two times higher for intact seeds from early flowers than for seeds from late flowers. Fruits from late flowers were, however, much more likely to escape seed predation than fruits from early flowers. Reproductive values of early and late flowers balanced at a predation intensity of 63%. Across 15 natural populations, the strength of selection for allocation to late flowers was positively correlated with mean seed predation intensity. Our results suggest that the optimal shape of the flowering schedule, in terms of the allocation between early and late flowers, is determined by the trade-off between offspring number and quality, and that variation in antagonistic interactions among populations influences the balancing of this trade-off. At the same time they illustrate that phenotypic selection analyses that fail to account for differences in offspring fitness might be misleading. PMID:26405752

  13. Trade-offs between seed output and life span - a quantitative comparison of traits between annual and perennial congeneric species.

    Science.gov (United States)

    Vico, Giulia; Manzoni, Stefano; Nkurunziza, Libère; Murphy, Kevin; Weih, Martin

    2016-01-01

    Perennial plants allocate more resources belowground, thus sustaining important ecosystem services. Hence, shifting from annual to perennial crops has been advocated towards a more sustainable agriculture. Nevertheless, wild perennial species have lower seed production than selected annuals, raising the questions of whether there is a fundamental trade-off between reproductive effort and life span, and whether such trade-off can be overcome through selection. In order to address these questions and to isolate life span from phylogenetic and environmental factors, we conducted a meta-analysis encompassing c. 3000 congeneric annual/perennial pairs from 28 genera. This meta-analysis is complemented with a minimalist model of long-term productivity in perennial species. Perennials allocate more resources belowground and less to seeds than congeneric annuals, independently of selection history. However, existing perennial wheat and rice could achieve yields similar to annuals if they survived three years and each year doubled their biomass, as other perennial grasses do. Selected perennial crops maintain the large belowground allocation of wild perennials, and thus can provide desired regulatory ecosystem services. To match the seed yield of annuals, biomass production of perennial grains must be increased to amounts attained by some perennial grasses - if this goal can be met, perennial crops can provide a more sustainable alternative to annuals. PMID:26214792

  14. Habitat Fragmentation Intensifies Trade-Offs between Biodiversity and Ecosystem Services in a Heathland Ecosystem in Southern England.

    Directory of Open Access Journals (Sweden)

    Justine E Cordingley

    Full Text Available While habitat fragmentation represents a major threat to global biodiversity, its impacts on provision of ecosystem services are largely unknown. We analysed biodiversity value and provision of multiple ecosystem services in 110 fragments of lowland heathland ecosystems in southern England, in which vegetation dynamics have been monitored for over 30 years. Decreasing fragment size was found to be associated with a decrease in biodiversity and recreational values, but an increase in relative carbon storage, aesthetic value and timber value. The trade-off between either biodiversity or recreational values with the other ecosystem services therefore became more pronounced as heathland size decreased. This was attributed to a higher rate of woody succession in smaller heathland fragments over the past three decades, and contrasting values of different successional vegetation types for biodiversity and provision of ecosystem services. These results suggest that habitat fragmentation can reduce the potential for developing "win win" solutions that contribute to biodiversity conservation while also supporting socio-economic development. Approaches to multi-purpose management of fragmented landscapes should therefore consider the potential trade-offs in ecosystem services and biodiversity associated with fragmentation, in order to make an effective contribution to sustainable development.

  15. Habitat Fragmentation Intensifies Trade-Offs between Biodiversity and Ecosystem Services in a Heathland Ecosystem in Southern England.

    Science.gov (United States)

    Cordingley, Justine E; Newton, Adrian C; Rose, Robert J; Clarke, Ralph T; Bullock, James M

    2015-01-01

    While habitat fragmentation represents a major threat to global biodiversity, its impacts on provision of ecosystem services are largely unknown. We analysed biodiversity value and provision of multiple ecosystem services in 110 fragments of lowland heathland ecosystems in southern England, in which vegetation dynamics have been monitored for over 30 years. Decreasing fragment size was found to be associated with a decrease in biodiversity and recreational values, but an increase in relative carbon storage, aesthetic value and timber value. The trade-off between either biodiversity or recreational values with the other ecosystem services therefore became more pronounced as heathland size decreased. This was attributed to a higher rate of woody succession in smaller heathland fragments over the past three decades, and contrasting values of different successional vegetation types for biodiversity and provision of ecosystem services. These results suggest that habitat fragmentation can reduce the potential for developing "win win" solutions that contribute to biodiversity conservation while also supporting socio-economic development. Approaches to multi-purpose management of fragmented landscapes should therefore consider the potential trade-offs in ecosystem services and biodiversity associated with fragmentation, in order to make an effective contribution to sustainable development. PMID:26114753

  16. Using the Sustainability Monitoring and Assessment Routine (SMART for the Systematic Analysis of Trade-Offs and Synergies between Sustainability Dimensions and Themes at Farm Level

    Directory of Open Access Journals (Sweden)

    Christian Schader

    2016-03-01

    Full Text Available When trying to optimize the sustainability performance of farms and farming systems, a consideration of trade-offs and synergies between different themes and dimensions is required. The aim of this paper is to perform a systematic analysis of trade-offs and synergies across all dimensions and themes. To achieve this aim we used the Sustainability Monitoring and Assessment Routine (SMART-Farm Tool which operationalizes the Sustainability Assessment of Food and Agriculture Systems (SAFA Guidelines by defining science-based indicator sets and assessment procedures. It identifies the degree of goal achievement with respect to the 58 themes defined in the SAFA Guidelines using an impact matrix that defines 327 indicators and 1769 relations between sustainability themes and indicators. We illustrate how the SMART-Farm Tool can be successfully applied to assess the sustainability performance of farms of different types and in different geographic regions. Our analysis revealed important synergies between themes within a sustainability dimension and across dimensions. We found major trade-offs within the environmental dimension and between the environmental and economic dimension. The trade-offs within the environmental dimension were even larger than the trade-offs with other dimensions. The study also underlines the importance of the governance dimension with regard to achieving a good level of performance in the other dimensions.

  17. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties.

    Science.gov (United States)

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-12-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer.

  18. Silicon Nanowires for Solar Thermal Energy Harvesting: an Experimental Evaluation on the Trade-off Effects of the Spectral Optical Properties.

    Science.gov (United States)

    Sekone, Abdoul Karim; Chen, Yu-Bin; Lu, Ming-Chang; Chen, Wen-Kai; Liu, Chia-An; Lee, Ming-Tsang

    2016-12-01

    Silicon nanowire possesses great potential as the material for renewable energy harvesting and conversion. The significantly reduced spectral reflectivity of silicon nanowire to visible light makes it even more attractive in solar energy applications. However, the benefit of its use for solar thermal energy harvesting remains to be investigated and has so far not been clearly reported. The purpose of this study is to provide practical information and insight into the performance of silicon nanowires in solar thermal energy conversion systems. Spectral hemispherical reflectivity and transmissivity of the black silicon nanowire array on silicon wafer substrate were measured. It was observed that the reflectivity is lower in the visible range but higher in the infrared range compared to the plain silicon wafer. A drying experiment and a theoretical calculation were carried out to directly evaluate the effects of the trade-off between scattering properties at different wavelengths. It is clearly seen that silicon nanowires can improve the solar thermal energy harnessing. The results showed that a 17.8 % increase in the harvest and utilization of solar thermal energy could be achieved using a silicon nanowire array on silicon substrate as compared to that obtained with a plain silicon wafer. PMID:26729219

  19. Navigating trade-offs in land-use planning: integrating human well-being into objective setting

    Directory of Open Access Journals (Sweden)

    Vanessa M. Adams

    2014-12-01

    Full Text Available There is an increasing demand for development of natural resources, which can be accompanied by environmental degradation. Planning for multiple land uses requires navigating trade-offs between social, economic, and environmental outcomes arising from different possible futures. To explore these trade-offs, we use the Daly River catchment, in Australia's Northern Territory, as a case study. The catchment contains areas of priority for both conservation and development. In response to the challenge of navigating the required trade-offs, the Daly River Management Advisory Committee (DRMAC initiated a land-use plan for the region. Both development and conservation of natural resources in the catchment will affect human well-being and the long-term provisioning of ecosystem services in diverse ways. To understand some of these impacts, an innovative engagement process was designed to elicit the relative importance of key factors to residents' well-being. The process identified 19 well-being factors grouped into four domains: biodiversity, socio-cultural, recreational, and commercial. Overall, the highest-ranked well-being factors were in the social-cultural and biodiversity domains while commercial values were ranked the least important. Respondents reported low satisfaction with commercial factors as well, noting concerns over environmental impacts from existing developments and sustainability of future developments. We identified differences in the reported importance values for several types of stakeholders, most notably between indigenous respondents and those employed in the agricultural sectors. Indigenous respondents placed greater importance on biodiversity and socio-cultural factors. Agricultural respondents placed greater importance on commercial factors. The outcomes of our engagement were integrated into DRMAC's process of objective-setting to ensure that objectives for each domain were included in land-use planning. Our results can also

  20. Effect of flower shape and size on foraging performance and trade-offs in a tropical hummingbird.

    Science.gov (United States)

    Temeles, Ethan J; Koulouris, Carolyn R; Sander, Sarah E; Kress, W John

    2009-05-01

    Matches between the bills of hummingbirds and the flowers they visit have been interpreted as examples of coadaptation and feeding specialization. Observations of birds feeding at flowers longer or shorter than their bills combined with a lack of experimental evidence for foraging trade-offs, however, fail to support these interpretations. We addressed these inconsistencies by considering a seldom-studied dimension of hummingbird-flower relationships, the shape of bills and flowers, through experiments on the Purple-throated Carib, Eulampis jugularis, and its major food plant, Heliconia, in the eastern Caribbean. Bills of male E. jugularis are considerably shorter and straighter than bills of females. We examined foraging performances and trade-offs during visits to natural heliconias and 34 artificial flowers of differing length and curvature. Supporting predictions based on matches between bill and flower morphology, handling times of females were significantly shorter than those of males at the long, curved flowers of a green morph of H. bihai. Contrary to predictions, handling times of males were not significantly shorter than handling times of females at the short flowers of H. caribaea. At artificial flowers, maximum extraction depths of females were significantly longer than maximum extraction depths of males at all curved flowers, but not at straight flowers. Handling times of females were significantly shorter than handling times of males at the longest artificial flowers for all curvatures, whereas handling times of males were significantly shorter at short, straight, artificial flowers, but only while hover-feeding without a perch. Within each sex, handling times were inversely related to bill length at long flowers for all shapes. Taken together, these performance trade-offs suggest that the long, curved bills of females are adapted for feeding from long, curved flowers, whereas the short bills of males are adapted for hover-feeding from short

  1. Effect of flower shape and size on foraging performance and trade-offs in a tropical hummingbird.

    Science.gov (United States)

    Temeles, Ethan J; Koulouris, Carolyn R; Sander, Sarah E; Kress, W John

    2009-05-01

    Matches between the bills of hummingbirds and the flowers they visit have been interpreted as examples of coadaptation and feeding specialization. Observations of birds feeding at flowers longer or shorter than their bills combined with a lack of experimental evidence for foraging trade-offs, however, fail to support these interpretations. We addressed these inconsistencies by considering a seldom-studied dimension of hummingbird-flower relationships, the shape of bills and flowers, through experiments on the Purple-throated Carib, Eulampis jugularis, and its major food plant, Heliconia, in the eastern Caribbean. Bills of male E. jugularis are considerably shorter and straighter than bills of females. We examined foraging performances and trade-offs during visits to natural heliconias and 34 artificial flowers of differing length and curvature. Supporting predictions based on matches between bill and flower morphology, handling times of females were significantly shorter than those of males at the long, curved flowers of a green morph of H. bihai. Contrary to predictions, handling times of males were not significantly shorter than handling times of females at the short flowers of H. caribaea. At artificial flowers, maximum extraction depths of females were significantly longer than maximum extraction depths of males at all curved flowers, but not at straight flowers. Handling times of females were significantly shorter than handling times of males at the longest artificial flowers for all curvatures, whereas handling times of males were significantly shorter at short, straight, artificial flowers, but only while hover-feeding without a perch. Within each sex, handling times were inversely related to bill length at long flowers for all shapes. Taken together, these performance trade-offs suggest that the long, curved bills of females are adapted for feeding from long, curved flowers, whereas the short bills of males are adapted for hover-feeding from short

  2. Trade-offs between lens complexity and real estate utilization in a free-space multichip global interconnection module

    Science.gov (United States)

    Milojkovic, Predrag; Christensen, Marc P.; Haney, Michael W.

    2006-07-01

    The FAST-Net (Free-space Accelerator for Switching Terabit Networks) concept uses an array of wide-field-of-view imaging lenses to realize a high-density shuffle interconnect pattern across an array of smart-pixel integrated circuits. To simplify the optics we evaluated the efficiency gained in replacing spherical surfaces with aspherical surfaces by exploiting the large disparity between narrow vertical cavity surface emitting laser (VCSEL) beams and the wide field of view of the imaging optics. We then analyzed trade-offs between lens complexity and chip real estate utilization and determined that there exists an optimal numerical aperture for VCSELs that maximizes their area density. The results provide a general framework for the design of wide-field-of-view free-space interconnection systems that incorporate high-density VCSEL arrays.

  3. When to stay, when to go: trade-offs for southern African arid-zone birds in times of drought

    Directory of Open Access Journals (Sweden)

    W.R.J. Dean

    2009-12-01

    Full Text Available Arid environments remind one of the punctuated equilibriumtheory of evolution: they experience long periods of stasis and low productivity, interrupted with episodic rainfall which spurs reproduction and movement. Birds, as highly dispersive organisms, are among the most dramatic indicators of these fluctuations. Here we review birds’ two main strategies, residency and nomadism, and the trade-offs faced by individuals in uncertain times. In general, wet years stimulate higher densities of nests (i.e. smaller territories, larger clutch sizes, unseasonal breeding, and at some times of year, higher breeding success. Rainfall above a certain threshold triggers breeding in resident species and an influx of nomadic species which breed and then move on. The environmental cues which trigger nomadism are sometimes poorly understood, but include distant thunderstorms for aquatic species, and perhaps for insectivores. Environmental cues that draw nomadic granivores to areas that have had recent rain are not known.

  4. Memory architecture for efficient utilization of SDRAM: a case study of the computation/memory access trade-off

    DEFF Research Database (Denmark)

    Gleerup, Thomas Møller; Holten-Lund, Hans Erik; Madsen, Jan;

    2000-01-01

    This paper discusses the trade-off between calculations and memory accesses in a 3D graphics tile renderer for visualization of data from medical scanners. The performance requirement of this application is a frame rate of 25 frames per second when rendering 3D models with 2 million triangles, i....... to use a memory access strategy with write-only and read-only phases, and a buffering system, which uses round-robin bank write-access combined with burst read-access........e. 50 million triangles per second, sustained (not peak). At present, a software implementation is capable of 3-4 frames per second for a 1 million triangle model. By using direct evaluation of certain interpolation parameters instead of forward differencing, writing back parameters to SDRAM is avoided...

  5. Equity aspects of risk management: trade-offs between public and occupational hazards in the nuclear industry

    International Nuclear Information System (INIS)

    Equity problems arise in risk management whenever a situation justifies dividing the exposed population into specific subgroups. The usual practice in radiation protection in the nuclear fuel cycle, which consists roughly in dividing the population into two groups (plant employees and the general public), assumes that management of the protection system for each group is relatively independent. But in the case of public protection against risks associated with pressurized-water reactors, for example, we show that this hypothesis of independence is not valid and that there are significant risk trade-offs between the public and the employees. This leads us to question the valuation of the implicit value of a man-sievert, depending on whether one is dealing with employees or the public, for the answer to this question strongly affects the result of any optimization of choices in radiation protection

  6. Trade-offs between Energy Efficiency improvements and additional Renewable Energy supply: A review of international experiences

    DEFF Research Database (Denmark)

    Baldini, Mattia; Klinge Jacobsen, Henrik

    -savings opportunities are missed. The aim of this paper is to review and evaluate international experiences on finding the optimal trade-off between efficiency improvements and additional renewable energy supply. A critical review of each technique, focusing on purposes, methodology and outcomes, is provided along......, current issues concerning climate change and fossil fuels depletion has moved attention towards cleaner ways to produce energy. This trend facilitated the breakthrough of renewable technologies. Since then, support policies have promoted the large deployment of renewables, without considering enough...... improvements made in the energy saving field. Indeed, less attention has been paid to implement energy efficiency measures in energy systems modeling, which has resulted in scenarios where expedients for a wise use of energy (e.g. energy savings and renewables’ share) are unbalanced and cost...

  7. On minimizing assignment errors and the trade-off between false positives and negatives in parentage analysis

    KAUST Repository

    Harrison, Hugo B.

    2013-11-04

    Genetic parentage analyses provide a practical means with which to identify parent-offspring relationships in the wild. In Harrison et al.\\'s study (2013a), we compare three methods of parentage analysis and showed that the number and diversity of microsatellite loci were the most important factors defining the accuracy of assignments. Our simulations revealed that an exclusion-Bayes theorem method was more susceptible to false-positive and false-negative assignments than other methods tested. Here, we analyse and discuss the trade-off between type I and type II errors in parentage analyses. We show that controlling for false-positive assignments, without reporting type II errors, can be misleading. Our findings illustrate the need to estimate and report both the rate of false-positive and false-negative assignments in parentage analyses. © 2013 John Wiley & Sons Ltd.

  8. Towards adaptive management of the natural capital: Disentangling trade-offs among marine activities and seagrass meadows.

    Science.gov (United States)

    Bas Ventín, Leticia; de Souza Troncoso, Jesús; Villasante, Sebastián

    2015-12-15

    This paper investigates the ecological, social and institutional dimensions of the synergies and trade-offs between seagrasses and human activities operating in the Natura 2000 protected site of San Simón Bay (Galicia, NW Spain). By means of a multidisciplinary approach that brings together the development of a biological inventory combined with participatory mapping processes we get key spatial and contextual understanding regarding how, where and why marine users interact with seagrasses and how seagrasses are considered in policy making. The results highlight the fisheries' reliance on seagrass meadows and the controversial links with shellfisheries. The study also reveals unresolved conflicts among those management plans that promote the protection of natural values and those responsible for the exploitation of marine resources. We conclude that the adoption of pre-planning bottom-up participatory processes is crucial for the design of realistic strategies where both seagrasses and human activities were considered as a couple system. PMID:26589639

  9. Investigation of cone-beam CT image quality trade-off for image-guided radiation therapy.

    Science.gov (United States)

    Bian, Junguo; Sharp, Gregory C; Park, Yang-Kyun; Ouyang, Jinsong; Bortfeld, Thomas; El Fakhri, Georges

    2016-05-01

    It is well-known that projections acquired over an angular range slightly over 180° (so-called short scan) are sufficient for fan-beam reconstruction. However, due to practical imaging conditions (projection data and reconstruction image discretization, physical factors, and data noise), the short-scan reconstructions may have different appearances and properties from the full-scan (scans over 360°) reconstructions. Nevertheless, short-scan configurations have been used in applications such as cone-beam CT (CBCT) for head-neck-cancer image-guided radiation therapy (IGRT) that only requires a small field of view due to the potential reduced imaging time and dose. In this work, we studied the image quality trade-off for full, short, and full/short scan configurations with both conventional filtered-backprojection (FBP) reconstruction and iterative reconstruction algorithms based on total-variation (TV) minimization for head-neck-cancer IGRT. Anthropomorphic and Catphan phantoms were scanned at different exposure levels with a clinical scanner used in IGRT. Both visualization- and numerical-metric-based evaluation studies were performed. The results indicate that the optimal exposure level and number of views are in the middle range for both FBP and TV-based iterative algorithms and the optimization is object-dependent and task-dependent. The optimal view numbers decrease with the total exposure levels for both FBP and TV-based algorithms. The results also indicate there are slight differences between FBP and TV-based iterative algorithms for the image quality trade-off: FBP seems to be more in favor of larger number of views while the TV-based algorithm is more robust to different data conditions (number of views and exposure levels) than the FBP algorithm. The studies can provide a general guideline for image-quality optimization for CBCT used in IGRT and other applications. PMID:27032676

  10. Trade-off in the sound localization abilities of early blind individuals between the horizontal and vertical planes.

    Science.gov (United States)

    Voss, Patrice; Tabry, Vanessa; Zatorre, Robert J

    2015-04-15

    There is substantial evidence that sensory deprivation leads to important cross-modal brain reorganization that is paralleled by enhanced perceptual abilities. However, it remains unclear how widespread these enhancements are, and whether they are intercorrelated or arise at the expense of other perceptual abilities. One specific area where such a trade-off might arise is that of spatial hearing, where blind individuals have been shown to possess superior monaural localization abilities in the horizontal plane, but inferior localization abilities in the vertical plane. While both of these tasks likely involve the use of monaural cues due to the absence of any relevant binaural signal, there is currently no proper explanation for this discrepancy, nor has any study investigated both sets of abilities in the same sample of blind individuals. Here, we assess whether the enhancements observed in the horizontal plane are related to the deficits observed in the vertical plane by testing sound localization in both planes in groups of blind and sighted persons. Our results show that the blind individuals who displayed the highest accuracy at localizing sounds monaurally in the horizontal plane are also the ones who exhibited the greater deficit when localizing in the vertical plane. These findings appear to argue against the idea of generalized perceptual enhancements in the early blind, and instead suggest the possibility of a trade-off in the localization proficiency between the two auditory spatial planes, such that learning to use monaural cues for the horizontal plane comes at the expense of using those cues to localize in the vertical plane.

  11. Ecological Trade-offs between Migration and Reproduction Are Mediated by the Nutrition-Sensitive Insulin-Signaling Pathway

    Science.gov (United States)

    Lin, Xinda; Yao, Yun; Wang, Bo; Emlen, Douglas J.; Lavine, Laura Corley

    2016-01-01

    Crowding and changes in food availability are two critical environmental conditions that impact an animal's trajectory toward either migration or reproduction. Many insects facing this challenge have evolved wing polyphenisms. When conditions favor reproduction, wing polyphenic species produce adults that either have no wings or short, non-functional wings. Facultative wing growth reflects a physiological and evolutionary trade-off between migration and reproduction, triggered by environmental conditions. How environmental cues are transduced to produce these alternative forms, and their associated ecological shift from migration to reproduction, remains an important unsolved problem in evolutionary ecology. The brown planthopper, a wing polymorphic insect exhibiting strong trade-offs in investment between migration and reproduction, is one of the most serious rice pests in Asia. In this study, we investigated the function of four genes in the insulin-signaling pathway known to couple nutrition with growth, PI3 Kinase (PI3K), PDK1, Akt (Protein Kinase B), and the forkhead gene FOXO. Using a combination of RNA interference and pharmacological inhibitor treatment, we show that all four genes contribute to tissue level regulation of wing polymorphic development in this insect. As predicted, silencing of the NlPI3K, NlAkt and NlPDK1 through dsRNA and with the pharmacological inhibitor Perifosine resulted in short-winged brown planthoppers, whereas knockdown of NlFOXO resulted in long-winged planthoppers. Morphometric analyses confirm that phenotypes from our manipulations mimic what would be found in nature, i.e., major parameters such as bristle number, wing area and body weight are not significantly different from non-experimental animals. Taken together, these data implicate the insulin-signaling pathway in the transduction of environmental factors into condition-dependent patterns of wing growth in insects. PMID:27143957

  12. Investigation of cone-beam CT image quality trade-off for image-guided radiation therapy

    Science.gov (United States)

    Bian, Junguo; Sharp, Gregory C.; Park, Yang-Kyun; Ouyang, Jinsong; Bortfeld, Thomas; El Fakhri, Georges

    2016-05-01

    It is well-known that projections acquired over an angular range slightly over 180° (so-called short scan) are sufficient for fan-beam reconstruction. However, due to practical imaging conditions (projection data and reconstruction image discretization, physical factors, and data noise), the short-scan reconstructions may have different appearances and properties from the full-scan (scans over 360°) reconstructions. Nevertheless, short-scan configurations have been used in applications such as cone-beam CT (CBCT) for head-neck-cancer image-guided radiation therapy (IGRT) that only requires a small field of view due to the potential reduced imaging time and dose. In this work, we studied the image quality trade-off for full, short, and full/short scan configurations with both conventional filtered-backprojection (FBP) reconstruction and iterative reconstruction algorithms based on total-variation (TV) minimization for head-neck-cancer IGRT. Anthropomorphic and Catphan phantoms were scanned at different exposure levels with a clinical scanner used in IGRT. Both visualization- and numerical-metric-based evaluation studies were performed. The results indicate that the optimal exposure level and number of views are in the middle range for both FBP and TV-based iterative algorithms and the optimization is object-dependent and task-dependent. The optimal view numbers decrease with the total exposure levels for both FBP and TV-based algorithms. The results also indicate there are slight differences between FBP and TV-based iterative algorithms for the image quality trade-off: FBP seems to be more in favor of larger number of views while the TV-based algorithm is more robust to different data conditions (number of views and exposure levels) than the FBP algorithm. The studies can provide a general guideline for image-quality optimization for CBCT used in IGRT and other applications.

  13. Is diversification in male reproductive traits driven by evolutionary trade-offs between weapons and nuptial gifts?

    Science.gov (United States)

    Liu, Xingyue; Hayashi, Fumio; Lavine, Laura C.; Yang, Ding

    2015-01-01

    Many male animals have evolved exaggerated traits that they use in combat with rival males to gain access to females and secure their reproductive success. But some male animals invest in nuptial gifts that gains them access to females. Both these reproductive strategies are costly in that resources are needed to produce the weapon or nuptial gift. In closely related species where both weapons and nuptial gifts are present, little is known about the potential evolutionary trade-off faced by males that have these traits. In this study, we use dobsonflies (order Megaloptera, family Corydalidae, subfamily Corydalinae) to examine the presence and absence of enlarged male weapons versus nuptial gifts within and among species. Many dobsonfly species are sexually dimorphic, and males possess extremely enlarged mandibles that they use in battles, whereas in other species, males produce large nuptial gifts that increase female fecundity. In our study, we show that male accessory gland size strongly correlates with nuptial gift size and that when male weapons are large, nuptial gifts are small and vice versa. We mapped weapons and nuptial gifts onto a phylogeny we constructed of 57 species of dobsonflies. Our among-species comparison shows that large nuptial gift production evolved in many species of dobsonfly but is absent from those with exaggerated weapons. This pattern supports the potential explanation that the trade-off in resource allocation between weapons and nuptial gifts is important in driving the diversity of male mating strategies seen in the dobsonflies, whereas reduced male–male competition in the species producing large spermatophores could be an alternative explanation on their loss of male weapons. Our results shed new light on the evolutionary interplay of multiple sexually selected traits in animals. PMID:25925103

  14. Allometric relationships between seed mass and seedling characteristics reveal trade-offs for neotropical gap-dependent species.

    Science.gov (United States)

    Daws, Matthew I; Ballard, Christopher; Mullins, Christopher E; Garwood, Nancy C; Murray, Brian; Pearson, Timothy R H; Burslem, David F R P

    2007-12-01

    A seed size-seed number trade-off exists because smaller seeds are produced in greater number but have a lower probability of establishment. This reduced establishment success of smaller-seeded species may be determined by biophysical constraints imposed by scaling rules. Root and shoot diameter, root growth extension rate (RGER) and shoot length at death for dark-grown seedlings are predicted to scale with the cube root of seed embryo and endosperm mass (m). We confirmed this expectation for ten neotropical gap-dependent tree species with an embryo and endosperm dry mass>1 mg. However, for nine smaller seeded species (mroot and shoot diameters were larger than expected, and consequently, RGER was slower than expected. The maximum shoot thrust of seedlings from seeds with masses>or=1 mg was comparable to the estimated force required to displace overlying litter, supporting the hypothesis that photoblastic behaviour only occurs in seeds with insufficient shoot thrust to displace overlying leaves. Using the model soil water, energy and transpiration to predict soil drying in small and large gaps, we showed that: (1) gaps that receive a significant amount of direct sunlight will dry more quickly than small gaps that do not, (2) compared to the wet-season, soil that is already dry at depth (i.e. the dry-season) will dry faster after rainfall (this drying would most likely kill seedlings from small seeds) and (3) even during the wet-season, dry periods of a few days in large gaps can kill shallow-rooted seedlings. We conclude that the smaller the seed, the more vulnerable its seedling would be to both covering by litter and soil drying because it can only emerge from shallow depths and has a slow RGER. Consequently, we suggest that these allometrically related factors contribute to the reduced establishment success of smaller-seeded species that underpins the seed size-seed number trade-off. PMID:17846798

  15. Is there an ideal REDD+ program? An analysis of policy trade-offs at the local level.

    Directory of Open Access Journals (Sweden)

    George A Dyer

    Full Text Available We use economy-wide simulation methods to analyze the outcome of a simple REDD+ program in a mixed subsistence/commercial-agriculture economy. Alternative scenarios help trace REDD+'s causal chain, revealing how trade-offs between the program's public and private costs and benefits determine its effectiveness, efficiency and equity (the 3Es. Scenarios reveal a complex relationship between the 3Es not evident in more aggregate analyses. Setting aside land as a carbon sink always influences the productivity of agriculture and its supply of non-market goods and services; but the overall returns to land and labor-which ultimately determine the opportunity cost of enrollment, the price of carbon and the distribution of gains and losses-depend on local conditions. In the study area, market-oriented landowners could enroll 30% of local land into a cost-effective program, but local subsistence demands would raise their opportunity costs as REDD+ unfurls, increasing the marginal cost of carbon. A combination of rent and wage changes would create net costs for most private stakeholders, including program participants. Increasing carbon prices undermines the program's efficiency without solving its inequities; expanding the program reduces inefficiencies but increases private costs with only minor improvements in equity. A program that prevents job losses could be the best option, but its efficiency compared to direct compensation could depend on program scale. Overall, neither the cost nor the 3Es of alternative REDD+ programs can be assessed without accounting for local demand for subsistence goods and services. In the context of Mexico's tropical highlands, a moderate-sized REDD+ program could at best have no net impact on rural households. REDD+ mechanisms should avoid general formulas by giving local authorities the necessary flexibility to address the trade-offs involved. National programs themselves should remain flexible enough to adjust for

  16. Optimal defense strategies in an idealized microbial food web under trade-off between competition and defense.

    Directory of Open Access Journals (Sweden)

    Selina Våge

    Full Text Available Trophic mechanisms that can generate biodiversity in food webs include bottom-up (growth rate regulating and top-down (biomass regulating factors. The top-down control has traditionally been analyzed using the concepts of "Keystone Predation" (KP and "Killing-the-Winner" (KtW, predominately occuring in discussions of macro- and micro-biological ecology, respectively. Here we combine the classical diamond-shaped food web structure frequently discussed in KP analyses and the KtW concept by introducing a defense strategist capable of partial defense. A formalized description of a trade-off between the defense-strategist's competitive and defensive ability is included. The analysis reveals a complex topology of the steady state solution with strong relationships between food web structure and the combination of trade-off, defense strategy and the system's nutrient content. Among the results is a difference in defense strategies corresponding to maximum biomass, production, or net growth rate of invading individuals. The analysis thus summons awareness that biomass or production, parameters typically measured in field studies to infer success of particular biota, are not directly acted upon by natural selection. Under coexistence with a competition specialist, a balance of competitive and defensive ability of the defense strategist was found to be evolutionarily stable, whereas stronger defense was optimal under increased nutrient levels in the absence of the pure competition specialist. The findings of success of different defense strategies are discussed with respect to SAR11, a highly successful bacterial clade in the pelagic ocean.

  17. Ecohydrological optimization of pattern and processes in water-limited ecosystems: A trade-off-based hypothesis

    Science.gov (United States)

    Caylor, Kelly K.; Scanlon, Todd M.; Rodriguez-Iturbe, Ignacio

    2009-08-01

    The complex interactions between plants, soils, and climates in semiarid ecosystems make it difficult to define specific ecohydrological optimization mechanisms that underlie observed spatiotemporal patterns of vegetation structure. There remains a clear need to develop conceptual models that are capable of interpreting and predicting spatial pattern formation in savannas (and similar dry woodland ecosystems), as well as metrics for assessing optimization or organization of patterns, as one scales from individual canopies to landscapes and beyond. In this article, we propose a unifying hypothesis regarding ecohydrological optimization of pattern and processes, namely, that vegetation patterns in water-limited environments are constrained in their ability to maximize water use by a need to simultaneously minimize water stress. We use this trade-off-based hypothesis to infer the function of dryland ecosystems under a wide range of scales and applications. Specifically, we examine spatial and temporal aspects of ecohydrological organization of vegetation patterns for three different cases: (1) patterns of regional-scale temporal organization across a regional climate gradient, (2) patterns of landscape-scale spatial organization within a semiarid drainage basin, and (3) patterns of individual-scale structural organization across varying soil textures. Although the insight gained from each of these examples is derived from specific modeling approaches, each of which contains its own unique set of assumptions and limitations, they are unified by our proposed ecohydrological trade-off approach that simultaneously considers both plant water deficit and plant water use as a diagnostic tool for assessing vegetation patterns in water-limited environments. It is our hope that the ongoing development of coupled ecological and hydrological models capable of assessing a diversity of interactions between plants, soils, and climates will lead to the emergence of more generalized

  18. An age-structured approach to modelling behavioural variation maintained by life-history trade-offs.

    Directory of Open Access Journals (Sweden)

    Matthew H T Chan

    Full Text Available There have been numerous empirical studies on the fitness consequences of behavioural syndromes in various animal taxa; however, the ecological and evolutionary implications on a population level are still poorly understood. To better understand these implications, we develop a non-linear age-structured mathematical model to qualitatively examine the evolutionary consequences of a heritable boldness personality trait within an animal population. We assume that this heritable boldness trait is positively correlated with boldness towards predators and intraspecific aggressiveness. This assumption leads to a growth/reproductive success versus mortality trade-off, which is thoroughly investigated and documented in the literature. Another life-history trade-off we include in the model is future versus current reproduction, which was shown by Wolf et al. to be a possible mechanism for the evolution of behavioural syndromes within an animal population. The stability of the system is analysed, whereby the characteristic equation is in the form of a homogeneous Fredholm equation of the second kind which depends on both the perturbation and equilibrium solution. The system is found to be stable due to the competition between individuals of similar boldness acting as a negative feedback mechanism. Using numerical simulations we examine the qualitative features of the solution to the system. In particular, we investigate the interplay between the mutation and competition strength between two individuals with different boldness, whereby we find that an increasing competition range acts to push individuals to both extremes of the shy-bold axis, while an increasing mutation range counteracts this effect. This qualitative trait of aggregation of individuals around the shy and bold extremes is also found when examining different birth, mortality and competition functions.

  19. Local SAR, global SAR, transmitter power and excitation accuracy trade-offs in low flip-angle parallel transmit pulse design

    OpenAIRE

    Guérin, Bastien; Gebhardt, Matthias; Cauley, Steven; Adalsteinsson, Elfar; Wald, Lawrence L.

    2013-01-01

    Purpose We propose a constrained optimization approach for designing parallel transmit (pTx) pulses satisfying all regulatory and hardware limits. We study the trade-offs between excitation accuracy, local and global specific absorption rate (SAR), and maximum and average power for small flip-angle pTx (eight channels) spokes pulses in the torso at 3 T and in the head at 7 T. Methods We compare the trade-offs between the above-mentioned quantities using the L-curve method. We use a p...

  20. A bistriphenylamine-substituted spirobifluorene derivative exhibiting excellent nonlinearity/transparency/thermal stability trade-off and strong two-photon induced blue fluorescence

    Energy Technology Data Exchange (ETDEWEB)

    Yin, Hongyao [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Xiao, Haibo, E-mail: xiaohb@shnu.edu.cn [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Ding, Lei [Department of Chemistry, Shanghai Normal University, Shanghai 200234 (China); Zhang, Chun; Ren, Aiming [State Key Laboratory of Theoretical and Computational Chemistry, Institute of Theoretical Chemistry, Jilin University, Changchun 130023 (China); Li, Bo [Key Laboratory of Polar Materials and Devices, Ministry of Education, East China Normal University, Shanghai 200241 (China)

    2015-02-01

    A spirobifluorene-bridged donor/donor chromophore, 2,7-bis-(4-(N,N-diphenylamino)phen-1-yl)-9,9′-spirobifluorene (SPF-TP), was found to combine excellent transparency in the near UV–visible region (λ{sub cut-off} ≤ 420 nm), large two-photon absorption cross-section (4.5 × 10{sup 3}GM) and high thermal stability (T{sub d} = 501 °C). In comparison to the reported two-photon absorption molecules, SPF-TP represents the best thermal stability so far described in the literature. The main electronic factors explaining the high two-photon absorption activities of SPF-TP were analyzed by theoretical calculations. Cyclic voltammograms were employed to explore the causes of the excellent transparency of SPF-TP. It was found that the spiroconjugation effect is responsible for the excellent nonlinearity/transparency/thermal stability trade-off in SPF-TP. In addition, SPF-TP is also a good two-photon induced blue fluorescent material with high fluorescence quantum yield (Φ = 0.90, in THF). - Highlights: • We report a molecule exhibiting excellent transparency. • The two-photon absorption cross-section is as large as 4.5 × 10{sup 3}GM. • The molecule exhibits excellent thermal stability. • The molecule is a good two-photon induced blue fluorescent material. • The spiroconjugation effect explains the excellent properties.