Science.gov

Sample records for pressure balancing trade-offs

  1. FAST Conformational Searches by Balancing Exploration/Exploitation Trade-Offs.

    PubMed

    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

  2. The trade-off characteristics of acoustic and pressure sensors for the NASP

    NASA Technical Reports Server (NTRS)

    Winkler, Martin; Bush, Chuck

    1992-01-01

    Results of a trade study for the development of pressure and acoustic sensors for use on the National Aerospace Plane (NASP) are summarized. Pressure sensors are needed to operate to 100 psia; acoustic sensors are needed that can give meaningful information about a 200 dB sound pressure level (SPL) environment. Both sensors will have to operate from a high temperature of 2000 F down to absolute zero. The main conclusions of the study are the following: (1) Diaphragm materials limit minimum size and maximum frequency response attainable. (2) No transduction is available to meet all the NASP requirements with existing technology. (3) Capacitive sensors are large relative to the requirement, have limited resolution and frequency response due to noise, and cable length is limited to approximately 20 feet. (4) Eddy current sensors are large relative to the requirement and have limited cable lengths. (5) Fiber optic sensors provide the possibility for a small sensor, even though present developments do not exhibit that characteristic. The need to use sapphire at high temperature complicates the design. Present high temperature research sensors suffer from poor resolution. A significant development effort will be required to realize the potential of fiber optics. (6) Short-term development seems to favor eddy current techniques with the penalty of larger size and reduced dynamic range for acoustic sensors. (7) Long-term development may favor fiber optics with the penalties of cost, schedule, and uncertainty.

  3. Balancing ecosystem services with energy and food security - Assessing trade-offs from reservoir operation and irrigation investments in Kenya's Tana Basin

    NASA Astrophysics Data System (ADS)

    Hurford, A. P.; Harou, J. J.

    2014-08-01

    Competition for water between key economic sectors and the environment means agreeing allocations is challenging. Managing releases from the three major dams in Kenya's Tana River basin with its 4.4 million inhabitants, 567 MW of installed hydropower capacity, 33 000 ha of irrigation and ecologically important wetlands and forests is a pertinent example. This research seeks firstly to identify and help decision-makers visualise reservoir management strategies which result in the best possible (Pareto-optimal) allocation of benefits between sectors. Secondly, it seeks to show how trade-offs between achievable benefits shift with the implementation of proposed new rice, cotton and biofuel irrigation projects. To approximate the Pareto-optimal trade-offs we link a water resources management simulation model to a multi-criteria search algorithm. The decisions or "levers" of the management problem are volume-dependent release rules for the three major dams and extent of investment in new irrigation schemes. These decisions are optimised for eight objectives covering the provision of water supply and irrigation, energy generation and maintenance of ecosystem services. Trade-off plots allow decision-makers to assess multi-reservoir rule-sets and irrigation investment options by visualising their impacts on different beneficiaries. Results quantify how economic gains from proposed irrigation schemes trade-off against the disturbance of ecosystems and local livelihoods that depend on them. Full implementation of the proposed schemes is shown to come at a high environmental and social cost. The clarity and comprehensiveness of "best-case" trade-off analysis is a useful vantage point from which to tackle the interdependence and complexity of "water-energy-food nexus" resource security issues.

  4. Balancing ecosystem services with energy and food security - assessing trade-offs for reservoir operation and irrigation investment in Kenya's Tana basin

    NASA Astrophysics Data System (ADS)

    Hurford, A. P.; Harou, J. J.

    2014-01-01

    Competition for water between key economic sectors and the environment means agreeing on allocation is challenging. Managing releases from the three major dams in Kenya's Tana River basin with its 4.4 million inhabitants, 567 MW of installed hydropower capacity, 33 000 ha of irrigation and ecologically important wetlands and forests is a pertinent example. This research seeks to identify and help decision-makers visualise reservoir management strategies which result in the best possible (Pareto-optimal) allocation of benefits between sectors. Secondly we seek to show how trade-offs between achievable benefits shift with the implementation of new proposed rice, cotton and biofuel irrigation projects. To identify the Pareto-optimal trade-offs we link a water resources management model to a multi-criteria search algorithm. The decisions or "levers" of the management problem are volume dependent release rules for the three major dams and extent of investment in new irrigation schemes. These decisions are optimised for objectives covering provision of water supply and irrigation, energy generation and maintenance of ecosystem services which underpin tourism and local livelihoods. Visual analytic plots allow decision makers to assess multi-reservoir rule-sets by understanding their impacts on different beneficiaries. Results quantify how economic gains from proposed irrigation schemes trade-off against disturbance of the flow regime which supports ecosystem services. Full implementation of the proposed schemes is shown to be Pareto-optimal, but at high environmental and social cost. The clarity and comprehensiveness of "best-case" trade-off analysis is a useful vantage point from which to tackle the interdependence and complexity of water-energy-food "nexus" challenges.

  5. Evaluating taboo trade-offs in ecosystems services and human well-being.

    PubMed

    Daw, Tim M; Coulthard, Sarah; Cheung, William W L; Brown, Katrina; Abunge, Caroline; Galafassi, Diego; Peterson, Garry D; McClanahan, Tim R; Omukoto, Johnstone O; Munyi, Lydiah

    2015-06-01

    Managing ecosystems for multiple ecosystem services and balancing the well-being of diverse stakeholders involves different kinds of trade-offs. Often trade-offs involve noneconomic and difficult-to-evaluate values, such as cultural identity, employment, the well-being of poor people, or particular species or ecosystem structures. Although trade-offs need to be considered for successful environmental management, they are often overlooked in favor of win-wins. Management and policy decisions demand approaches that can explicitly acknowledge and evaluate diverse trade-offs. We identified a diversity of apparent trade-offs in a small-scale tropical fishery when ecological simulations were integrated with participatory assessments of social-ecological system structure and stakeholders' well-being. Despite an apparent win-win between conservation and profitability at the aggregate scale, food production, employment, and well-being of marginalized stakeholders were differentially influenced by management decisions leading to trade-offs. Some of these trade-offs were suggested to be "taboo" trade-offs between morally incommensurable values, such as between profits and the well-being of marginalized women. These were not previously recognized as management issues. Stakeholders explored and deliberated over trade-offs supported by an interactive "toy model" representing key system trade-offs, alongside qualitative narrative scenarios of the future. The concept of taboo trade-offs suggests that psychological bias and social sensitivity may exclude key issues from decision making, which can result in policies that are difficult to implement. Our participatory modeling and scenarios approach has the potential to increase awareness of such trade-offs, promote discussion of what is acceptable, and potentially identify and reduce obstacles to management compliance. PMID:26038547

  6. Evaluating taboo trade-offs in ecosystems services and human well-being

    PubMed Central

    Coulthard, Sarah; Cheung, William W. L.; Brown, Katrina; Abunge, Caroline; Galafassi, Diego; Peterson, Garry D.; McClanahan, Tim R.; Omukoto, Johnstone O.; Munyi, Lydiah

    2015-01-01

    Managing ecosystems for multiple ecosystem services and balancing the well-being of diverse stakeholders involves different kinds of trade-offs. Often trade-offs involve noneconomic and difficult-to-evaluate values, such as cultural identity, employment, the well-being of poor people, or particular species or ecosystem structures. Although trade-offs need to be considered for successful environmental management, they are often overlooked in favor of win-wins. Management and policy decisions demand approaches that can explicitly acknowledge and evaluate diverse trade-offs. We identified a diversity of apparent trade-offs in a small-scale tropical fishery when ecological simulations were integrated with participatory assessments of social–ecological system structure and stakeholders’ well-being. Despite an apparent win-win between conservation and profitability at the aggregate scale, food production, employment, and well-being of marginalized stakeholders were differentially influenced by management decisions leading to trade-offs. Some of these trade-offs were suggested to be “taboo” trade-offs between morally incommensurable values, such as between profits and the well-being of marginalized women. These were not previously recognized as management issues. Stakeholders explored and deliberated over trade-offs supported by an interactive “toy model” representing key system trade-offs, alongside qualitative narrative scenarios of the future. The concept of taboo trade-offs suggests that psychological bias and social sensitivity may exclude key issues from decision making, which can result in policies that are difficult to implement. Our participatory modeling and scenarios approach has the potential to increase awareness of such trade-offs, promote discussion of what is acceptable, and potentially identify and reduce obstacles to management compliance. PMID:26038547

  7. Effects of parasite pressure on parasite mortality and reproductive output in a rodent-flea system: inferring host defense trade-offs.

    PubMed

    Warburton, Elizabeth M; Kam, Michael; Bar-Shira, Enav; Friedman, Aharon; Khokhlova, Irina S; Koren, Lee; Asfur, Mustafa; Geffen, Eli; Kiefer, Daniel; Krasnov, Boris R; Degen, A Allan

    2016-09-01

    Evaluating host resistance via parasite fitness helps place host-parasite relationships within evolutionary and ecological contexts; however, few studies consider both these processes simultaneously. We investigated how different levels of parasite pressure affect parasite mortality and reproductive success in relationship to host defense efforts, using the rodent Gerbillus nanus and the flea Xenopsylla conformis as a host-parasite system. Fifteen immune-naïve male rodents were infested with 20, 50, or 100 fleas for four weeks. During this time number of new imagoes produced per adult flea (our flea reproductive output metric), flea mortality, and change in circulating anti-flea immunoglobulin G (our measure of adaptive immune defense) were monitored. Three hypotheses guided this work: (1) increasing parasite pressure would heighten host defenses; (2) parasite mortality would increase and parasite reproductive output would decrease with increasing investment in host defense; and (3) hosts under high parasite pressure could invest in behavioral and/or immune responses. We predicted that at high infestation levels (a) parasite mortality would increase; (b) flea reproductive output per individual would decrease; and (c) host circulating anti-flea antibody levels would increase. The hypotheses were partially supported. Flea mortality significantly increased and flea reproductive output significantly decreased as flea pressure increased. Host adaptive immune defense did not significantly change with increasing flea pressure. Therefore, we inferred that investment in host behavioral defense, either alone or in combination with density-dependent effects, may be more efficient at increasing flea mortality and decreasing flea reproductive output than antibody production during initial infestation in this system. PMID:27130319

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

    PubMed

    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. PMID:16323810

  9. Dual shell pressure balanced vessel

    DOEpatents

    Fassbender, Alexander G.

    1992-01-01

    A dual-wall pressure balanced vessel for processing high viscosity slurries at high temperatures and pressures having an outer pressure vessel and an inner vessel with an annular space between the vessels pressurized at a pressure slightly less than or equivalent to the pressure within the inner vessel.

  10. Expanding population edges: theories, traits, and trade-offs.

    PubMed

    Chuang, Angela; Peterson, Christopher R

    2016-02-01

    Recent patterns of global change have highlighted the importance of understanding the dynamics and mechanisms of species range shifts and expansions. Unique demographic features, spatial processes, and selective pressures can result in the accumulation and evolution of distinctive phenotypic traits at the leading edges of expansions. We review the characteristics of expanding range margins and highlight possible mechanisms for the appearance of phenotypic differences between individuals at the leading edge and core of the range. The development of life history traits that increase dispersal or reproductive ability is predicted by theory and supported with extensive empirical evidence. Many examples of rapid phenotypic change are associated with trade-offs that may influence the persistence of the trait once expansion ends. Accounting for the effects of edge phenotypes and related trade-offs could be critical for predicting the spread of invasive species and population responses to climate change. PMID:26426311

  11. Trade-offs in Our Energy Future.

    ERIC Educational Resources Information Center

    Canipe, Stephen L.

    The purpose of this activity is to make students aware that there is no free energy source for the present or the future and that all technologies are potential threats to the environment. The activity consists of a short reading (discussing basic trade-offs, issues, and decisions related to petroleum, coal, and nuclear energy sources) and student…

  12. Fluid pressure balanced seal

    NASA Technical Reports Server (NTRS)

    Marsh, H. W. (Inventor)

    1966-01-01

    A seal which increases in effectiveness with increasing pressure is presented. The seal's functional capability throughout both static and dynamic operation makes it particularly useful for sealing ball valve ports. Other features of the seal include the ability to seal two opposed surfaces simultaneously, tolerance of small misalignments, tolerance of wide temperature ranges, ability to maintain positive sealing contact under conditions of internal or external pressurization, and ability to conform to slight irregularities in seal or surface contours.

  13. Balanced pressure gerotor fuel pump

    DOEpatents

    Raney, Michael Raymond; Maier, Eugen

    2004-08-03

    A gerotor pump for pressurizing gasoline fuel is capable of developing pressures up to 2.0 MPa with good mechanical and volumetric efficiency and satisfying the durability requirements for an automotive fuel pump. The pump has been designed with optimized clearances and by including features that promote the formation of lubricating films of pressurized fuel. Features of the improved pump include the use of a shadow port in the side plate opposite the outlet port to promote balancing of high fuel pressures on the opposite sides of the rotors. Inner and outer rotors have predetermined side clearances with the clearances of the outer rotor being greater than those of the inner rotor in order to promote fuel pressure balance on the sides of the outer rotor. Support of the inner rotor and a drive shaft on a single bushing with bearing sleeves maintains concentricity. Additional features are disclosed.

  14. Source-structure trade-offs in ambient noise correlations

    NASA Astrophysics Data System (ADS)

    Fichtner, Andreas

    2015-07-01

    We analyse the physics and geometry of trade-offs between Earth structure and noise sources in interstation noise correlations. Our approach is based on the computation of off-diagonal Hessian elements that describe the extent to which variations in noise sources can compensate for variations in Earth structure without changing the misfit beyond the measurement uncertainty. Despite the fact that all ambient noise inverse problems are special in terms of their receiver configuration and data, some general statements concerning source-structure trade-offs can be made: (i) While source-structure trade-offs may be reduced to some extent by clever measurement design, there are inherent trade-offs that can generally not be avoided. These inherent trade-offs may lead to a mispositioning of structural heterogeneities when the noise source distribution is unknown. (ii) When attenuation is weak, source-structure trade-offs in ambient noise correlations are a global phenomenon, meaning that there is no noise source perturbation that does not trade-off with some Earth structure, and vice versa. (iii) The most significant source-structure trade-offs occur within two elliptically shaped regions connecting a potential noise source perturbation to each one of the receivers. (iv) Far from these elliptical regions, only small-scale structure can trade off against changes in the noise source. (v) While source-structure trade-offs mostly decay with increasing attenuation, they are nearly unaffected by attenuation when the noise source perturbation is located near the receiver-receiver line. This work is intended to contribute to the development of joint source-structure inversions of ambient noise correlations, and in particular to an understanding of the extent to which source-structure trade-offs may be reduced. It furthermore establishes the foundation of future resolution analyses that properly quantify trade-offs between noise sources and Earth structure.

  15. Operational trade-offs in reservoir control

    NASA Astrophysics Data System (ADS)

    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. Global agriculture and carbon trade-offs

    PubMed Central

    Johnson, Justin Andrew; Runge, Carlisle Ford; Senauer, Benjamin; Foley, Jonathan; Polasky, Stephen

    2014-01-01

    Feeding a growing and increasingly affluent world will require expanded agricultural production, which may require converting grasslands and forests into cropland. Such conversions can reduce carbon storage, habitat provision, and other ecosystem services, presenting difficult societal trade-offs. In this paper, we use spatially explicit data on agricultural productivity and carbon storage in a global analysis to find where agricultural extensification should occur to meet growing demand while minimizing carbon emissions from land use change. Selective extensification saves ∼6 billion metric tons of carbon compared with a business-as-usual approach, with a value of approximately $1 trillion (2012 US dollars) using recent estimates of the social cost of carbon. This type of spatially explicit geospatial analysis can be expanded to include other ecosystem services and other industries to analyze how to minimize conflicts between economic development and environmental sustainability. PMID:25114254

  17. Global agriculture and carbon trade-offs.

    PubMed

    Johnson, Justin Andrew; Runge, Carlisle Ford; Senauer, Benjamin; Foley, Jonathan; Polasky, Stephen

    2014-08-26

    Feeding a growing and increasingly affluent world will require expanded agricultural production, which may require converting grasslands and forests into cropland. Such conversions can reduce carbon storage, habitat provision, and other ecosystem services, presenting difficult societal trade-offs. In this paper, we use spatially explicit data on agricultural productivity and carbon storage in a global analysis to find where agricultural extensification should occur to meet growing demand while minimizing carbon emissions from land use change. Selective extensification saves ∼ 6 billion metric tons of carbon compared with a business-as-usual approach, with a value of approximately $1 trillion (2012 US dollars) using recent estimates of the social cost of carbon. This type of spatially explicit geospatial analysis can be expanded to include other ecosystem services and other industries to analyze how to minimize conflicts between economic development and environmental sustainability. PMID:25114254

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

    NASA Astrophysics Data System (ADS)

    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.

  19. Conceptualising and managing trade-offs in sustainability assessment

    SciTech Connect

    Morrison-Saunders, Angus; Pope, Jenny

    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

  20. Reproduction-Immunity Trade-Offs in Insects.

    PubMed

    Schwenke, Robin A; Lazzaro, Brian P; Wolfner, Mariana F

    2016-01-01

    Immune defense and reproduction are physiologically and energetically demanding processes and have been observed to trade off in a diversity of female insects. Increased reproductive effort results in reduced immunity, and reciprocally, infection and activation of the immune system reduce reproductive output. This trade-off can manifest at the physiological level (within an individual) and at the evolutionary level (genetic distinction among individuals in a population). The resource allocation model posits that the trade-off arises because of competition for one or more limiting resources, and we hypothesize that pleiotropic signaling mechanisms regulate allocation of that resource between reproductive and immune processes. We examine the role of juvenile hormone, 20-hydroxyecdysone, and insulin/insulin-like growth factor-like signaling in regulating both oogenesis and immune system activity, and propose a signaling network that may mechanistically regulate the trade-off. Finally, we discuss implications of the trade-off in an ecological and evolutionary context. PMID:26667271

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

    PubMed

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

    2016-02-01

    species (Target 12). Synergies between targets must be identified and secured soon and trade-offs must be minimized before the options for co-benefits are reduced by human pressures. PMID:26041135

  2. Quantifying ecosystem service trade-offs: the case of an urban floodplain in Vienna, Austria.

    PubMed

    Sanon, Samai; Hein, Thomas; Douven, Wim; Winkler, Peter

    2012-11-30

    Wetland ecosystems provide multiple functions and services for the well-being of humans. In urban environments, planning and decision making about wetland restoration inevitably involves conflicting objectives, trade-offs, uncertainties and conflicting value judgments. This study applied trade-off and multi criteria decision analysis to analyze and quantify the explicit trade-offs between the stakeholder's objectives related to management options for the restoration of an urban floodplain, the Lobau, in Vienna, Austria. The Lobau has been disconnected from the main channel of the Danube River through flood protection schemes 130 years ago that have reduced the hydraulic exchange processes. Urban expansion has also changed the adjacent areas and led to increased numbers of visitors, which hampers the maximum potential for ecosystem development and exerts additional pressure on the sensitive habitats in the national park area. The study showed that increased hydraulic connectivity would benefit several stakeholders that preferred the ecological development of the floodplain habitats. However, multiple uses including fishery, agriculture and recreation, exploring the maximum potential in line with national park regulations, were also possible under the increased hydraulic connectivity options. The largest trade-offs were quantified to be at 0.50 score between the ecological condition of the aquatic habitats and the drinking water production and 0.49 score between the ecological condition of the terrestrial habitats and the drinking water production. At this point, the drinking water production was traded-off with 0.40 score, while the ecological condition of the aquatic habitats and the ecological condition of the terrestrial habitats were traded off with 0.30 and 0.23 score, respectively. The majority of the stakeholders involved preferred the management options that increased the hydraulic connectivity compared with the current situation which was not preferred by

  3. Rainbow trout in seasonal environments: phenotypic trade-offs across a gradient in winter duration.

    PubMed

    Lea, Ellen V; Mee, Jonathan A; Post, John R; Rogers, Sean M; Mogensen, Stephanie

    2015-11-01

    Survival through periods of resource scarcity depends on the balance between metabolic demands and energy storage. The opposing effects of predation and starvation mortality are predicted to result in trade-offs between traits that optimize fitness during periods of resource plenty (e.g., during the growing season) and those that optimize fitness during periods of resource scarcity (e.g., during the winter). We conducted a common environment experiment with two genetically distinct strains of rainbow trout to investigate trade-offs due to (1) the balance of growth and predation risk related to foraging rate during the growing season and (2) the allocation of energy to body size prior to the winter. Fry (age 0) from both strains were stocked into replicate natural lakes at low and high elevation that differed in winter duration (i.e., ice cover) by 59 days. Overwinter survival was lowest in the high-elevation lakes for both strains. Activity rate and growth rate were highest at high elevation, but growing season survival did not differ between strains or between environments. Hence, we did not observe a trade-off between growth and predation risk related to foraging rate. Growth rate also differed significantly between the strains across both environments, which suggests that growth rate is involved in local adaptation. There was not, however, a difference between strains or between environments in energy storage. Hence, we did not observe a trade-off between growth and storage. Our findings suggest that intrinsic metabolic rate, which affects a trade-off between growth rate and overwinter survival, may influence local adaptation in organisms that experience particularly harsh winter conditions (e.g., extended periods trapped beneath the ice in high-elevation lakes) in some parts of their range. PMID:26640659

  4. Reproduction-longevity trade-offs reflect diet, not adaptation.

    PubMed

    Attisano, A; Moore, A J; Moore, P J

    2012-05-01

    A tenet of life history evolution is that allocation of limited resources results in trade-offs, such as that between reproduction and lifespan. Reproduction and lifespan are also influenced proximately by differences in the availability of specific nutrients. What is unknown is how the evolution of the ability to use a nutritionally novel diet is reflected in this fundamental trade-off. Does the evolution of the ability to use a nutritionally novel food maintain the trade-off in reproduction and longevity, or do the proximate effects of nutrition alter the adapted trade-off? We tested this by measuring trade-offs in male milkweed bugs, Oncopeltus fasciatus, fed either an adapted diet of sunflower or the ancestral diet of milkweed. Sunflower-fed males lived longer but invested less in reproduction, both in mating and fertility. Milkweed-fed males invested in both mating and fertility at the expense of survival. The evolution of an expanded diet was not constrained by the existing trade-off, but instead was accompanied by a different trade-off between reproduction and longevity. We suggest that this occurs because diets differ in promoting germ line development or longevity. PMID:22356585

  5. The Grayscale/Spatial Resolution Trade-Off and Its Impact on Display System Design

    NASA Technical Reports Server (NTRS)

    Gille, Jennifer; Larimer, Jim; Martin, Russel; Statler, Irving C. (Technical Monitor)

    1994-01-01

    We examine technology trade-offs related to the grayscale/spatial resolution trade-off for AMLCD-based display systems. We present new empirical results from our study of the human grayscale/spatial resolution trade-off.

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

    USGS Publications Warehouse

    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.

  7. Trade-offs across space, time, and ecosystem services

    USGS Publications Warehouse

    Rodriguez, J.P.; Beard, T.D., Jr.; Bennett, E.M.; Cumming, Graeme S.; Cork, S.J.; Agard, J.; Dobson, A.P.; Peterson, G.D.

    2006-01-01

    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. Successful strategies will

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

    PubMed

    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

  9. A Trade-Off Study Revealing Nested Timescales of Constraint

    PubMed Central

    Wijnants, M. L.; Cox, R. F. A.; Hasselman, F.; Bosman, A. M. T.; Van Orden, G.

    2012-01-01

    This study investigates human performance in a cyclic Fitts task at three different scales of observation, either in the presence (difficult condition) or in the absence (easy condition) of a speed–accuracy trade-off. At the fastest scale, the harmonicity of the back and forth movements, which reflects the dissipation of mechanical energy, was measured within the timeframe of single trials. At an intermediate scale, speed and accuracy measures were determined over a trial. The slowest scale pertains to the temporal structure of movement variability, which evolves over multiple trials. In the difficult condition, reliable correlations across each of the measures corroborated a coupling of nested scales of performance. Participants who predominantly emphasized the speed-side of the trade-off (despite the instruction to be both fast and accurate) produced more harmonic movements and clearer 1/f scaling in the produced movement time series, but were less accurate and produced more random variability in the produced movement amplitudes (vice versa for more accurate participants). This implied that speed–accuracy trade-off was accompanied by a trade-off between temporal and spatial streams of 1/f scaling, as confirmed by entropy measures. In the easy condition, however, no trade-offs nor couplings among scales of performance were observed. Together, these results suggest that 1/f scaling is more than just a byproduct of cognition. These findings rather support the claim that interaction-dominant dynamics constitute a coordinative basis for goal-directed behavior. PMID:22654760

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

    PubMed

    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

  11. [Trade-offs in oral drug product development].

    PubMed

    Kondo, Hiromu; Sako, Kazuhiro

    2015-01-01

    Drug products are developed to meet multiple targets, thereby increasing their value. Pharmaceutical scientists encounter several trade-offs during the development of novel oral formulations. These trade-offs are generated by their desire to supply the highest possible quality products under the prevailing conditions of limited time and cost, and feasible options. When there are two incompatible factors, it is sometimes difficult to dismiss one element. This is because a quality target product profile (QTPP) is critical for each product being developed, and all elements should basically be satisfied with the criteria. Therefore, technological innovation becomes important to overcome the trade-offs. This article introduces examples of such innovations which have been successful in doing this, as well as some encountered in the oral formulation development and in the selection of proper dosage forms. Based on these examples, points to be considered in order to produce the drug product are thoroughly discussed. PMID:25747218

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

    PubMed

    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

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

    PubMed

    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

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

    PubMed Central

    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

  15. Atomic Layer Etching of Silicon to Solve ARDE-Selectivity-Profile-Uniformity Trade-Offs

    NASA Astrophysics Data System (ADS)

    Wang, Mingmei; Ranjan, Alok; Ventzek, Peter; Koshiishi, Akira

    2014-10-01

    With shrinking critical dimensions, dry etch faces more and more challenges. Minimizing each of aspect ratio dependent etching (ARDE), bowing, undercut, selectivity, and within die uniformly across a wafer are met by trading off one requirement against another. At the root of the problem is that roles radical flux, ion flux and ion energy play may be both good and bad. Increasing one parameter helps meeting one requirement but hinders meeting the other. Self-limiting processes like atomic layer etching (ALE) promise a way to escape the problem of balancing trade-offs. ALE was realized in the mid-1990s but the industrial implementation has been slow. In recent years interest in ALE has revived. We present how ARDE, bowing/selectivity trade-offs may be overcome by varying radical/ion ratio, byproduct re-deposition. We overcome many of the practical implementation issues associated with ALE by precise passivation process control. The Monte Carlo Feature Profile Model (MCFPM) is used to illustrate realistic scenarios built around an Ar/Cl2 chemistry driven etch of Si masked by SiO2. We demonstrate that ALE can achieve zero ARDE and infinite selectivity. Profile control depends on careful management of the ion energies and angles. For ALE to be realized in production environment, tight control of IAD is a necessary. Experimental results are compared with simulation results to provide context to the work.

  16. Unintended consequences and trade-offs of fish passage

    USGS Publications Warehouse

    8. McLaughlin, Robert L.; Smyth, Eric R.; Castro-Santos, Theodore; Jones, Michael L.; Koops, Marten A.; Pratt, Thomas C.; Vélez-Espino, Luis-Antonio

    2012-01-01

    We synthesized evidence for unintended consequences and trade-offs associated with the passage of fishes. Provisioning of fish passageways at dams and dam removals are being carried out increasingly as resource managers seek ways to reduce fragmentation of migratory fish populations and restore biodiversity and nature-like ecosystem services in tributaries altered by dams. The benefits of provisioning upstream passage are highlighted widely. Possible unwanted consequences and trade-offs of upstream passage are coming to light, but remain poorly examined and underappreciated. Unintended consequences arise when passage of native and desirable introduced fishes is delayed, undone (fallback), results in patterns of movement and habitat use that reduce Darwinian fitness (e.g. ecological traps), or is highly selective taxonomically and numerically. Trade-offs arise when passage decisions intended to benefit native species interfere with management decisions intended to control the unwanted spread of non-native fishes and aquatic invertebrates, or genes, diseases and contaminants carried by hatchery and wild fishes. These consequences and trade-offs will vary in importance from system to system and can result in large economic and environmental costs. For some river systems, decisions about how to manage fish passage involve substantial risks and could benefit from use of a formal, structured process that allows transparent, objective and, where possible, quantitative evaluation of these risks. Such a process can also facilitate the design of an adaptive framework that provides valuable insights into future decisions.

  17. Information Trade-Offs for Optical Quantum Communication

    NASA Astrophysics Data System (ADS)

    Wilde, Mark M.; Hayden, Patrick; Guha, Saikat

    2012-04-01

    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 well-known protocols for quantum channels. A 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 by itself. Previously, the benefits of trade-off coding that had been found were too small to be of practical value (viz., for the dephasing and the universal cloning machine channels). In this Letter, we demonstrate that the associated performance gains are in fact remarkably high for several physically relevant bosonic channels that model free-space or fiber-optic links, thermal-noise channels, and amplifiers. We show that significant performance gains from trade-off coding also apply when trading photon-number resources between transmitting public and private classical information simultaneously over secret-key-assisted bosonic channels.

  18. Information trade-offs for optical quantum communication.

    PubMed

    Wilde, Mark M; Hayden, Patrick; Guha, Saikat

    2012-04-01

    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 well-known protocols for quantum channels. A 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 by itself. Previously, the benefits of trade-off coding that had been found were too small to be of practical value (viz., for the dephasing and the universal cloning machine channels). In this Letter, we demonstrate that the associated performance gains are in fact remarkably high for several physically relevant bosonic channels that model free-space or fiber-optic links, thermal-noise channels, and amplifiers. We show that significant performance gains from trade-off coding also apply when trading photon-number resources between transmitting public and private classical information simultaneously over secret-key-assisted bosonic channels. PMID:22540777

  19. Exploration–exploitation trade-off features a saltatory search behaviour

    PubMed Central

    Volchenkov, Dimitri; Helbach, Jonathan; Tscherepanow, Marko; Kühnel, Sina

    2013-01-01

    Searching experiments conducted in different virtual environments over a gender-balanced group of people revealed a gender irrelevant scale-free spread of searching activity on large spatio-temporal scales. We have suggested and solved analytically a simple statistical model of the coherent-noise type describing the exploration–exploitation trade-off in humans (‘should I stay’ or ‘should I go’). The model exhibits a variety of saltatory behaviours, ranging from Lévy flights occurring under uncertainty to Brownian walks performed by a treasure hunter confident of the eventual success. PMID:23782535

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

    SciTech Connect

    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 approach is illustrated using a

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

    NASA Astrophysics Data System (ADS)

    Funo, Ken; Ueda, Masahito

    2015-12-01

    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.

  2. Trade-off analysis for environmental projects: An annotated bibliography

    SciTech Connect

    Feather, T.D.; Harrington, K.W.; Capan, D.T.

    1995-08-01

    This is a report with an attached annotated bibliography. This study explores the literature for analytical techniques that can support the complex decision-making process associated with Corps of Engineers environmental projects. The literature review focuses on opportunities for using trade-off methodologies and group processes in environmental plan formulation and evaluation. The work was conducted under the Evaluation Framework Work Unit within the Evaluation of Environmental Investments Research Program.

  3. The energy trade-off between growth and longevity.

    PubMed

    Hou, Chen

    2013-09-01

    Understanding the trade-offs between organisms' life history traits has been a major goal of physiology, ecology and evolution. In the last few decades, two types of intra-specific studies have highlighted the trade-off between growth and longevity. First, diet restriction (DR), as an environmental intervention, has been shown to suppress growth and extend the lifespan of a broad range of animals. Second, genetic studies have also shown that mice, whose growth hormone function is genetically modified (GM), grow slower and live longer than their wild-type siblings. Despite a wealth of empirical data, still largely missing is a theoretical framework that specifies and makes quantitative predictions on this trade-off. Here, I present a mechanistic model based on the principles of energy conservation. The model quantifies explicitly how DR and GM alter the animal's energy budget, and channel metabolic energy to somatic maintenance by suppressing growth, thereby extending lifespan. Data from a diverse set of empirical studies on small rodents supports the predictions of the model. More importantly, the model reveals that although DR and GM are two different methods to extend lifespan, i.e., environmental vs. genetic, the underlying mechanisms of them are the same from the energetic viewpoint. PMID:23872259

  4. Potential trade-offs in treatment of premanifest Huntington's disease.

    PubMed

    Albin, Roger L; Burke, James F

    2015-09-01

    The potential long-term consequences of treatments delaying manifestations of neurodegenerative diseases have not been explored. Using Huntington disease (HD) data and Markov chain Monte Carlo methods, we simulated the effects of therapies with equivalent effects on time to onset of HD and survival with HD. Our results suggest substantial potential trade-offs in effects of these therapies; significant delays in time to onset of HD were accompanied by significant prolongations of survival after onset of HD. Under a variety of assumptions, treatments delaying onset of HD result in some patients likely to have a greater increase in survival with manifest HD compared to delays in time to onset of HD. Our results suggest that future work in HD should be sensitive to the potential existence of such trade-offs and that understanding the preferences of HD patients and the broader HD community will be increasingly important. Future research, trial design, and treatment strategies in HD and other mid-life-onset neurodegenerative disorders should consider the possibility of trade-offs in long-term consequences of disease-modifying treatments. PMID:26173644

  5. Speed and Endurance Do Not Trade Off in Phrynosomatid Lizards.

    PubMed

    de Albuquerque, Ralph Lacerda; Bonine, Kevin E; Garland, Theodore

    2015-01-01

    Trade-offs are a common focus of study in evolutionary biology and in studies of locomotor physiology and biomechanics. A previous comparative study of 12 species of European lacertid lizards found a statistically significant negative correlation between residual locomotor speed and stamina (controlling for variation in body size), consistent with ideas about trade-offs in performance based on variation in muscle fiber type composition and other subordinate traits. To begin examining the generality of this finding in other groups of squamates, we measured maximal sprint running speed on a high-speed treadmill and endurance at 1.0 km/h (0.28 m/s) in 14 species of North American phrynosomatid lizards, plus a sample of nine additional species to encompass some of the broadscale diversity of lizards. We used both conventional and phylogenetically informed regression analyses to control for some known causes of performance variation (body size, stockiness, body temperature) and then computed residual performance values. We found no evidence for a trade-off between speed and endurance among the 14 phrynosomatids or among the 23 species in the extended data set. Possible explanations for the apparent difference between lacertids and phrynosomatids are discussed. PMID:26658411

  6. Army ants dynamically adjust living bridges in response to a cost-benefit trade-off.

    PubMed

    Reid, Chris R; Lutz, Matthew J; Powell, Scott; Kao, Albert B; Couzin, Iain D; Garnier, Simon

    2015-12-01

    The ability of individual animals to create functional structures by joining together is rare and confined to the social insects. Army ants (Eciton) form collective assemblages out of their own bodies to perform a variety of functions that benefit the entire colony. Here we examine ‟bridges" of linked individuals that are constructed to span gaps in the colony's foraging trail. How these living structures adjust themselves to varied and changing conditions remains poorly understood. Our field experiments show that the ants continuously modify their bridges, such that these structures lengthen, widen, and change position in response to traffic levels and environmental geometry. Ants initiate bridges where their path deviates from their incoming direction and move the bridges over time to create shortcuts over large gaps. The final position of the structure depended on the intensity of the traffic and the extent of path deviation and was influenced by a cost-benefit trade-off at the colony level, where the benefit of increased foraging trail efficiency was balanced by the cost of removing workers from the foraging pool to form the structure. To examine this trade-off, we quantified the geometric relationship between costs and benefits revealed by our experiments. We then constructed a model to determine the bridge location that maximized foraging rate, which qualitatively matched the observed movement of bridges. Our results highlight how animal self-assemblages can be dynamically modified in response to a group-level cost-benefit trade-off, without any individual unit's having information on global benefits or costs. PMID:26598673

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

    PubMed

    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

  8. Army ants dynamically adjust living bridges in response to a cost–benefit trade-off

    PubMed Central

    Reid, Chris R.; Lutz, Matthew J.; Powell, Scott; Kao, Albert B.; Couzin, Iain D.; Garnier, Simon

    2015-01-01

    The ability of individual animals to create functional structures by joining together is rare and confined to the social insects. Army ants (Eciton) form collective assemblages out of their own bodies to perform a variety of functions that benefit the entire colony. Here we examine ‟bridges” of linked individuals that are constructed to span gaps in the colony’s foraging trail. How these living structures adjust themselves to varied and changing conditions remains poorly understood. Our field experiments show that the ants continuously modify their bridges, such that these structures lengthen, widen, and change position in response to traffic levels and environmental geometry. Ants initiate bridges where their path deviates from their incoming direction and move the bridges over time to create shortcuts over large gaps. The final position of the structure depended on the intensity of the traffic and the extent of path deviation and was influenced by a cost–benefit trade-off at the colony level, where the benefit of increased foraging trail efficiency was balanced by the cost of removing workers from the foraging pool to form the structure. To examine this trade-off, we quantified the geometric relationship between costs and benefits revealed by our experiments. We then constructed a model to determine the bridge location that maximized foraging rate, which qualitatively matched the observed movement of bridges. Our results highlight how animal self-assemblages can be dynamically modified in response to a group-level cost–benefit trade-off, without any individual unit’s having information on global benefits or costs. PMID:26598673

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

    PubMed Central

    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

  10. Seasonal polyphenism and developmental trade-offs between flight ability and egg laying in a pierid butterfly

    PubMed Central

    Karlsson, Bengt; Johansson, Anna

    2008-01-01

    Butterflies have competing demands for flight ability depending on, for example, mating system, predation pressure, the localization of host plants and dispersal needs. The flight apparatus, however, is costly to manufacture and therefore trade-offs are expected since resources are limited and must be allocated between flight ability and other functions, such as reproduction. Trade-offs between flight and reproduction may be difficult to reveal since they interact with other factors and can be confounded by differences in resource consumption. Previous studies have shown that adults of the summer generation of Pieris napi have relatively larger thoraxes compared with the spring generation. To study whether difference in thorax size results in a trade-off between flight ability and reproduction among the two generations, we conducted a split-brood experiment under common garden conditions. Our results show that summer generation adults have a higher dispersal capacity measured as flight duration in five different temperatures. Reproductive output differed between the two developmental pathways; spring generation females had a significantly higher output of eggs compared with summer generation females. We suggest that this is a consequence of a resource-allocation trade-off made during pupal development implemented by different demands for flight between the spring and summer generations. The significance of this finding is discussed in relation to reproduction and mobility in butterflies. PMID:18522912

  11. Visualising Pareto-optimal trade-offs helps move beyond monetary-only criteria for water management decisions

    NASA Astrophysics Data System (ADS)

    Hurford, Anthony; Harou, Julien

    2014-05-01

    Water related eco-system services are important to the livelihoods of the poorest sectors of society in developing countries. Degradation or loss of these services can increase the vulnerability of people decreasing their capacity to support themselves. New approaches to help guide water resources management decisions are needed which account for the non-market value of ecosystem goods and services. In case studies from Brazil and Kenya we demonstrate the capability of many objective Pareto-optimal trade-off analysis to help decision makers balance economic and non-market benefits from the management of existing multi-reservoir systems. A multi-criteria search algorithm is coupled to a water resources management simulator of each basin to generate a set of Pareto-approximate trade-offs representing the best case management decisions. In both cases, volume dependent reservoir release rules are the management decisions being optimised. In the Kenyan case we further assess the impacts of proposed irrigation investments, and how the possibility of new investments impacts the system's trade-offs. During the multi-criteria search (optimisation), performance of different sets of management decisions (policies) is assessed against case-specific objective functions representing provision of water supply and irrigation, hydropower generation and maintenance of ecosystem services. Results are visualised as trade-off surfaces to help decision makers understand the impacts of different policies on a broad range of stakeholders and to assist in decision-making. These case studies show how the approach can reveal unexpected opportunities for win-win solutions, and quantify the trade-offs between investing to increase agricultural revenue and negative impacts on protected ecosystems which support rural livelihoods.

  12. Computerized Techniques for Calibrating Pressure Balances

    NASA Astrophysics Data System (ADS)

    Simpson, D. I.

    1994-01-01

    Pressure balances are generally calibrated by the cross-floating technique, where the forces acting on two similar devices in hydrostatic equilibrium are compared. It is a skilled and time-consuming process which has not previously lent itself to significant automation; computers have mostly been used only to calculate results after measurements have been taken. The objective of the present work was to develop real-time computerized measurement techniques to ease the calibration task, which would fully integrate into a single package with versatile software for calculating and displaying results. The calibration process is now conducted by studying graphical computer displays which derive their inputs from differential-pressure transducers and capacitance or optical displacement sensors. The mass imbalance between oil-operated pressure balances is calculated by interpolating between changes in piston rate-of-fall. Differential-pressure transducers are used to estimate mass imbalances between gas-operated balances, and a quick in situ method for determining their sensitivity has been developed. The new techniques have been successfully applied to a variety of pressure balance designs and substantial reductions in calibration times have been achieved. Reduced levels of scatter have revealed small systematic differences between gauge and absolute modes of operation.

  13. Predicting Cost/Performance Trade-Offs for Whitney: A Commodity Computing Cluster

    NASA Technical Reports Server (NTRS)

    Becker, Jeffrey C.; Nitzberg, Bill; VanderWijngaart, Rob F.; Kutler, Paul (Technical Monitor)

    1997-01-01

    Recent advances in low-end processor and network technology have made it possible to build a "supercomputer" out of commodity components. We develop simple models of the NAS Parallel Benchmarks version 2 (NPB 2) to explore the cost/performance trade-offs involved in building a balanced parallel computer supporting a scientific workload. We develop closed form expressions detailing the number and size of messages sent by each benchmark. Coupling these with measured single processor performance, network latency, and network bandwidth, our models predict benchmark performance to within 30%. A comparison based on total system cost reveals that current commodity technology (200 MHz Pentium Pros with 100baseT Ethernet) is well balanced for the NPBs up to a total system cost of around $1,000,000.

  14. Predicting Cost/Performance Trade-offs For Whitney: A Commodity Computing Cluster

    NASA Technical Reports Server (NTRS)

    Becker, Jeffrey C.; Nitzberg, Bill; VanDerWijngaart, Rob F.; Tweten, Dave (Technical Monitor)

    1998-01-01

    Recent advances in low-end processor and network technology have made it possible to build a "supercomputer" out of commodity components. We develop simple models of the NAS Parallel Benchmarks version 2 (NPB 2) to explore the cost/performance trade-offs involved in building a balanced parallel computer supporting a scientific workload. By measuring single processor benchmark performance, network latency, and network bandwidth, and using closed form expressions detailing the number and size of messages sent by each benchmark, our models predict benchmark performance to within 30%. A comparison based on total system cost reveals that current commodity technology (200 MHz Pentium Pros with 100baseT Ethernet) is well balanced for the NPBs up to a total system cost of around $ 1,000,000.

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

    PubMed

    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

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

    PubMed Central

    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

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

    PubMed

    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

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

    SciTech Connect

    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.

  19. Network Implementation Trade-Offs in Existing Homes

    NASA Astrophysics Data System (ADS)

    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.

  20. Universality of efficiency at unified trade-off optimization

    NASA Astrophysics Data System (ADS)

    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.

  1. Analyzing staffing trade-offs on acute care hospital units.

    PubMed

    Berkow, Steven; Vonderhaar, Kate; Stewart, Jennifer; Virkstis, Katherine; Terry, Anne

    2014-10-01

    Given today's resource-limited environment, nurse leaders must make judicious staffing decisions to deliver safe, cost-effective care. Investing in 1 element of staffing often requires scaling back in another. A national cross section of acute care hospital unit leaders was surveyed regarding staffing resources, including nurse workload, education, specialty certification, experience, and level of support staff. The authors report findings from the survey and discuss the trade-offs observed among units regarding nurse-to-patient ratios and the proportion of baccalaureate-prepared nurses. PMID:25208268

  2. Laser space rendevous and docking trade-off

    NASA Technical Reports Server (NTRS)

    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.

  3. IXO/XMS Detector Trade-Off Study

    NASA Technical Reports Server (NTRS)

    Kilbourne, Caroline Anne; deKorte, P.; Smith, S.; Hoevers, H.; vdKuur, J.; Ezoe, Y.; Ullom, J.

    2010-01-01

    This document presents the outcome of the detector trade-off for the XMS instrument on IXO. This trade-off is part of the Cryogenic instrument Phase-A study as proposed to ESA in the Declaration of Interest SRONXMS-PL-2009-003 dated June 6, 2009. The detector consists of two components: a core array for the highest spectral resolution and an outer array to increase the field of view substantially with modest increase in the number of read-out channels. Degraded resolution of the outer array in comparison with the core array is accepted in order to make this scheme possible. The two detector components may be a single unit or separate units. These arrays comprise pixels and the components that allow them to be arrayed. Each pixel comprises a thermometer, an absorber, and the thermal links between them and to the rest of the array. These links may be interfaces or distinct components. The array infrastructure comprises the mechanical structure of the array, the arrangement of the leads, and features added to improve the integrated thermal properties of the array in the focal-plane assembly.

  4. Limits and trade-offs of topological network robustness.

    PubMed

    Priester, Christopher; Schmitt, Sebastian; Peixoto, Tiago P

    2014-01-01

    We investigate the trade-off between the robustness against random and targeted removal of nodes from a network. To this end we utilize the stochastic block model to study ensembles of infinitely large networks with arbitrary large-scale structures. We present results from numerical two-objective optimization simulations for networks with various fixed mean degree and number of blocks. The results provide strong evidence that three different blocks are sufficient to realize the best trade-off between the two measures of robustness, i.e. to obtain the complete front of Pareto-optimal networks. For all values of the mean degree, a characteristic three block structure emerges over large parts of the Pareto-optimal front. This structure can be often characterized as a core-periphery structure, composed of a group of core nodes with high degree connected among themselves and to a periphery of low-degree nodes, in addition to a third group of nodes which is disconnected from the periphery, and weakly connected to the core. Only at both extremes of the Pareto-optimal front, corresponding to maximal robustness against random and targeted node removal, a two-block core-periphery structure or a one-block fully random network are found, respectively. PMID:25250565

  5. DISTRIBUTED PROCESSING TRADE-OFF MODEL FOR ELECTRIC UTILITY OPERATION

    NASA Technical Reports Server (NTRS)

    Klein, S. A.

    1994-01-01

    The Distributed processing Trade-off Model for Electric Utility Operation is based upon a study performed for the California Institute of Technology's Jet Propulsion Laboratory. This study presented a technique that addresses the question of trade-offs between expanding a communications network or expanding the capacity of distributed computers in an electric utility Energy Management System (EMS). The technique resulted in the development of a quantitative assessment model that is presented in a Lotus 1-2-3 worksheet environment. The model gives EMS planners a macroscopic tool for evaluating distributed processing architectures and the major technical and economic tradeoffs as well as interactions within these architectures. The model inputs (which may be varied according to application and need) include geographic parameters, data flow and processing workload parameters, operator staffing parameters, and technology/economic parameters. The model's outputs are total cost in various categories, a number of intermediate cost and technical calculation results, as well as graphical presentation of Costs vs. Percent Distribution for various parameters. The model has been implemented on an IBM PC using the LOTUS 1-2-3 spreadsheet environment and was developed in 1986. Also included with the spreadsheet model are a number of representative but hypothetical utility system examples.

  6. Trade-offs in prenatal detection of Down syndrome.

    PubMed Central

    Serra-Prat, M; Gallo, P; Jovell, A J; Aymerich, M; Estrada, M D

    1998-01-01

    OBJECTIVES: This paper presents the results of different screening policies for prenatal detection of Down syndrome that would allow decision makers to make informed choices. METHODS: A decision analysis model was built to compare 8 screening policies with regard to a selected set of outcome measures. Probabilities used in the analysis were obtained from official administrative data reports in Spain and Catalonia and from data published in the medical literature. Sensitivity analyses were carried out to test the robustness of screening policies' results to changes in uptake rates, diagnostic accuracy, and resources consumed. RESULTS: Selected screening policies posed major trades-offs regarding detection rates, false-positive results, fetal loss, and costs of the programs. All outcome measures considered were found quite robust to changes in uptake rates. Sensitivity and specificity rates of screening tests were shown to be the most influential factors in the outcome measures considered. CONCLUSIONS: The disclosed trade-offs emphasize the need to comprehensively inform decision makers about both positive and negative consequences of adopting one screening policy or another. PMID:9550991

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

    PubMed Central

    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

  8. Sentinel-1 EPS Architecture And Power Conversion Trade-Off

    NASA Astrophysics Data System (ADS)

    Catalano, Toni Fabio; Costanitini, Stefano; Daparati, Giorgio

    2011-10-01

    The paper will present the selected EPS (Electrical Power System) Architecture for the Sentinel-1 mission. After a brief survey of Sentinel-1 mission, the EPS design will be illustrated, with particular focus on the architecture adopted for SAW (Solar Array Wing) power conversion and relevant trade-off. In the early phase of the project, various trade-offs have been carried out in order to define the suitable Sentinel- 1 EPS architecture. Mainly the following subjects have been exploited: -BTA (Battery) technology and topology identification; -SAW rotation strategy and relevant mechanism selection; -primary power bus voltage selection; - distribution and protection philosophy; -SAW power conditioning strategy. All those, and many minor ones, have been evaluated singly to assess the best solution for the individual problem and all together to evaluate the consequences of the interactions at subsystem level to be finally reflected in system budget and architecture sizing. As the choice of the most appropriate conditioning architecture is directly influenced by chosen EPS architecture and has direct impact on S/C (Spacecraft) capability to sustain required operational profile, specially considering the long mission lifetime plus mission extension, dedicated analysis and simulations have been carried out. This paper focuses on SAW conditioning trade-off analysis results along with a brief description of the in- house developed simulator used during this study. Basing on project inputs such as mission operational scenarios, system requirement and HW constraints, a direct comparison of the performances achievable with the different accounted conditioning systems, S3R, MPPT buck and MPPT boost, is given. Finally, the outcomes of simulations run lead to a substantial equivalence of the three architecture topologies if no specific BTA configuration is accounted (ideal configuration). When considering different BTA topologies (s-p or p-s) and related possible failures, a

  9. Power-speed trade-off in parallel prefix circuits

    NASA Astrophysics Data System (ADS)

    Vanichayobon, Sirirut; Dhall, Sudarshan K.; Lakshmivarahan, S.; Antonio, John K.

    2002-06-01

    Optimizing area and speed in parallel prefix circuit have been considered important for a long time. The issue of power consumption in these circuits, however, has not been addressed. The paper presents a comparative study of different parallel prefix circuits form the point of view of power-speed trade-off. The power consumption and the power-delay product of seven parallel prefix circuits were compared. A linear output capacitance assumption, combined with PSpice simulations, is used to investigate the power consumption in the parallel prefix circuits. The degrees of freedom studied include different parallel prefix algorithms and voltage scaling. The results show that the use of the linear output capacitance assumption provides results that are consistent with those obtained using PSpice simulations. The study can help identify parallel prefix algorithms with the desirable power consumption with a given throughput.

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

    PubMed Central

    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.

  11. Trade-off study of data storage technologies

    NASA Technical Reports Server (NTRS)

    Kadyszewski, R. V.

    1977-01-01

    The need to store and retrieve large quantities of data at modest cost has generated the need for an economical, compact, archival mass storage system. Very significant improvements in the state-of-the-art of mass storage systems have been accomplished through the development of a number of magnetic, electro-optical, and other related devices. This study was conducted in order to do a trade-off between these data storage devices and the related technologies in order to determine an optimum approach for an archival mass data storage system based upon a comparison of the projected capabilities and characteristics of these devices to yield operational systems in the early 1980's.

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

    PubMed

    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

  13. Mechanical Trade-offs in Experimentally Evolved Multicellular Yeast

    NASA Astrophysics Data System (ADS)

    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.

  14. Trade-offs in osmoregulation and parallel shifts in molecular function follow ecological transitions to freshwater in the Alewife.

    PubMed

    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

  15. Trade-offs in osmoregulation and parallel shifts in molecular function follow ecological transitions to freshwater in the Alewife

    USGS Publications Warehouse

    Velotta, Jonathan P.; McCormick, Stephen; Schultz, Eric T.

    2015-01-01

    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.

  16. Trade-off studies on ODUS spectrograph design

    NASA Astrophysics Data System (ADS)

    Kawashima, Takahiro; Kuze, Akihiko; Tanii, Jun; Mori, Shigetaka; Ogawa, Toshihiro; Suzuki, Makoto; Shibasaki, Kazuo; Yamamoto, Yasuji; Sano, Takuki

    2001-02-01

    ODUS (Ozone Dynamics Ultraviolet Spectrometer) on the GCOM (Global Change Observation Mission)-A1 mission will measure the ozone, SO2, NO2 and other trace constituents both in the stratosphere and in the troposphere through the backscatter ultraviolet (BUV) technique from 306 nm to 420 nm. In the present paper, the design concepts of the ODUS were clarified and a trade-off study among various spectrometer types was done. Since GCOM-A1 will have a non-sun-synchronous orbit, the thermal condition during a recurrent cycle will be more variable than that of a sun-synchronous orbit. Therefore, misalignment caused by thermal stress distortion was expected to be the most critical matter. As a result, a simple conventional Ebert type spectrometer was employed. However astigmatism is a matter of serious concern for the Ebert type spectrometer, because it leads to a significant loss of the input photon flux caused by the image extension of the entrance slit in the direction of detector height. The optimal slit height was determined by the trade-off study between high throughput and the image distortion due to astigmatism. As a detector, a linear photodiode array was employed for ODUS. As the detector is custom made, the shape and the arrangement of each photodiode pixel can be modified by changing the mask design. We optimized the detector height for each photodiode pixel to maximize the SN ratio by calculating the instrument function. According to the above process, the detector was newly fabricated with a dramatic change of the mask design. The new detector was combined with the previously fabricated laboratory model spectrometer. We successfully obtained atmospheric scatter data on the ground with a signal to noise ratio of 350 at the wavelength of around 400 nm.

  17. Performance trade-offs in in situ chemostat NMR.

    PubMed

    Castro, C D; Koretsky, A P; Domach, M M

    1999-01-01

    Investigating cell cultures with NMR requires high cell densities to provide adequate signal-to-noise, or scans must be summed over long time periods and short-term events are lost. The mixing within a chemostat can be used to shorten the time required to acquire informative in situ NMR spectra from cell cultures. However, performance trade-offs can occur between net signal, spectral resolution, and oxygenation due to sampling volume, conductivity, gas bubble, and fluid flow effects. These trade-offs and the effect of different mixing regimes were theoretically analyzed to quantify how device design decisions impact performance. The results were found to concur with data from cell-free NMR experiments performed in 18 mS/cm conductivity medium. The results also guided the redesign of an NMR bioreactor in terms of relative radio frequency (rf) coil and sample dimensions and other factors. The design, which entails using chemostat mixing to shunt sample through a rf coil in ca. 0.4 s, provides adequate oxygenation for the 4-16% (v/v) cell suspensions examined. Gains realized include lower conductive losses, better magnetic field homogeneity, and the exclusion of gas bubbles from the sampling zone. These gains enable the acquistion of spectra from dilute (3-4% v/v) Saccharomyces cerevisiae chemostat cultures in 6.9 min with high resolution in both the orthophosphate and the beta-NTP regions. Samples with 16% (v/v) cells also yield useful spectra within 0.5-1.0 min. PMID:10194393

  18. Modeling drivers' speed selection as a trade-off behavior.

    PubMed

    Tarko, Andrew P

    2009-05-01

    This paper proposes a new model of driver-preferred speeds derived from the assumption that drivers trade-off a portion of their safety for a time gain. The risk of receiving a ticket for speeding is also considered. A trip disutility concept is selected to combine the three components of speed choice (safety, time, and enforcement). The perceived crash risk and speed enforcement are considered as speed deterrents while the perceived value of a time gain is considered as a speed enticement. According to this concept, speeds that minimize the perceived trip disutility are preferred by drivers. The modeled trade-off behavior does not have to be fully rational since it is affected by drivers' preferences and their ability to perceive the risk. As such, the proposed framework follows the concept of bound rationality. The attractiveness of the model lies in its parameters being estimable with the observed preferred speeds and then interpretable as the factors of risk perception, the subjective value of time, and the perceived risk of speed enforcement. The proposed method may successfully supplement behavioral studies based on a driver survey. The study focuses on four-lane rural and suburban roads in Indiana, USA. The behavior of two types of drivers (trucks and cars) is modeled. The selection of test sites was such that the roads and other local characteristics varied across the studied sites while the population of drivers could be assumed as the same. The density of intersections, land development along the road, and the presence of sidewalks were the identified prominent risk perception factors. Another interesting finding is that the speed limit seems to encourage slow drivers to drive faster and fast drivers to drive slower. PMID:19393813

  19. No evidence of trade-offs in the evolution of sperm numbers and sperm size in mammals.

    PubMed

    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

  20. Morphological differences between habitats are associated with physiological and behavioural trade-offs in stickleback (Gasterosteus aculeatus)

    PubMed Central

    Seebacher, Frank; Webster, Mike M.; James, Rob S.; Tallis, Jason; Ward, Ashley J. W.

    2016-01-01

    Local specialization can be advantageous for individuals and may increase the resilience of the species to environmental change. However, there may be trade-offs between morphological responses and physiological performance and behaviour. Our aim was to test whether habitat-specific morphology of stickleback (Gasterosteus aculeatus) interacts with physiological performance and behaviour at different salinities. We rejected the hypothesis that deeper body shape of fish from habitats with high predation pressure led to decreases in locomotor performance. However, there was a trade-off between deeper body shape and muscle quality. Muscle of deeper-bodied fish produced less force than that of shallow-bodied saltmarsh fish. Nonetheless, saltmarsh fish had lower swimming performance, presumably because of lower muscle mass overall coupled with smaller caudal peduncles and larger heads. Saltmarsh fish performed better in saline water (20 ppt) relative to freshwater and relative to fish from freshwater habitats. However, exposure to salinity affected shoaling behaviour of fish from all habitats and shoals moved faster and closer together compared with freshwater. We show that habitat modification can alter phenotypes of native species, but local morphological specialization is associated with trade-offs that may reduce its benefits. PMID:27429785

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

    PubMed

    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

  2. Anti-microbial Use in Animals: How to Assess the Trade-offs.

    PubMed

    Rushton, J

    2015-04-01

    Antimicrobials are widely used in preventive and curative medicine in animals. Benefits from curative use are clear - it allows sick animals to be healthy with a gain in human welfare. The case for preventive use of antimicrobials is less clear cut with debates on the value of antimicrobials as growth promoters in the intensive livestock industries. The possible benefits from the use of antimicrobials need to be balanced against their cost and the increased risk of emergence of resistance due to their use in animals. The study examines the importance of animals in society and how the role and management of animals is changing including the use of antimicrobials. It proposes an economic framework to assess the trade-offs of anti-microbial use and examines the current level of data collection and analysis of these trade-offs. An exploratory review identifies a number of weaknesses. Rarely are we consistent in the frameworks applied to the economic assessment anti-microbial use in animals, which may well be due to gaps in data or the prejudices of the analysts. There is a need for more careful data collection that would allow information on (i) which species and production systems antimicrobials are used in, (ii) what active substance of antimicrobials and the application method and (iii) what dosage rates. The species need to include companion animals as well as the farmed animals as it is still not known how important direct versus indirect spread of resistance to humans is. In addition, research is needed on pricing antimicrobials used in animals to ensure that prices reflect production and marketing costs, the fixed costs of anti-microbial development and the externalities of resistance emergence. Overall, much work is needed to provide greater guidance to policy, and such work should be informed by rigorous data collection and analysis systems. PMID:25903492

  3. Reciprocal transplant reveals trade-off of resource quality and predation risk in the field.

    PubMed

    Ruehl, Clifton B; Trexler, Joel C

    2015-09-01

    Balancing trade-offs between avoiding predators and acquiring food enables animals to maximize fitness. Quantifying their relative contribution to vital rates in nature is challenging because predator abundance and nutrient enrichment are often confounded. We employed a reciprocal transplant study design to separate these confounded effects on growth and reproduction of snails at wetland sites along a gradient of predator threats and phosphorus (P) enrichment associated with a canal. We held snails in mesh bags that allowed the passage of waterborne predator cues and fed them local or transplanted periphyton. Molluscivores were more abundant near the canal, and snails tethered near the canal suffered 33% greater mortality than those tethered far from it (far sites). The greatest difference in snail growth rates was at the far sites where growth on far periphyton was 48% slower than on P-enriched (near canal) periphyton. Close proximity to the canal reduced growth on near periphyton by 21% compared to growth on the same periphyton far from the canal; there was no difference in growth rate on either periphyton type when snails were raised near the canal. Snails laid 81% more egg masses at far sites than at near sites, regardless of periphyton origin. Top-down and bottom-up processes were elevated near the canal, and their effects canceled on growth, but not reproduction. Phenotypic trade-offs such as these may explain why some taxa show little response to nutrient enrichment, compared to others, or that the effects of nutrient enrichment may be context dependent. PMID:25916894

  4. Anti-microbial Use in Animals: How to Assess the Trade-offs

    PubMed Central

    Rushton, J

    2015-01-01

    Antimicrobials are widely used in preventive and curative medicine in animals. Benefits from curative use are clear – it allows sick animals to be healthy with a gain in human welfare. The case for preventive use of antimicrobials is less clear cut with debates on the value of antimicrobials as growth promoters in the intensive livestock industries. The possible benefits from the use of antimicrobials need to be balanced against their cost and the increased risk of emergence of resistance due to their use in animals. The study examines the importance of animals in society and how the role and management of animals is changing including the use of antimicrobials. It proposes an economic framework to assess the trade-offs of anti-microbial use and examines the current level of data collection and analysis of these trade-offs. An exploratory review identifies a number of weaknesses. Rarely are we consistent in the frameworks applied to the economic assessment anti-microbial use in animals, which may well be due to gaps in data or the prejudices of the analysts. There is a need for more careful data collection that would allow information on (i) which species and production systems antimicrobials are used in, (ii) what active substance of antimicrobials and the application method and (iii) what dosage rates. The species need to include companion animals as well as the farmed animals as it is still not known how important direct versus indirect spread of resistance to humans is. In addition, research is needed on pricing antimicrobials used in animals to ensure that prices reflect production and marketing costs, the fixed costs of anti-microbial development and the externalities of resistance emergence. Overall, much work is needed to provide greater guidance to policy, and such work should be informed by rigorous data collection and analysis systems. PMID:25903492

  5. Energy-Information Trade-Offs between Movement and Sensing

    PubMed Central

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

    2010-01-01

    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

  6. Optimization based trade-off analysis of biodiesel crop production for managing a German agricultural catchment

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In agricultural production, the existence of multiple trade-offs among several conflicting objectives, such as food production, water quantity, water quality, biodiversity and ecosystem services, is well known. However, quantification of the trade-offs among objectives in bioenergy crop production i...

  7. 76 FR 70408 - Information Collection; Understanding Value Trade-Offs Regarding Fire Hazard Reduction Programs...

    Federal Register 2010, 2011, 2012, 2013, 2014

    2011-11-14

    ... Forest Service Information Collection; Understanding Value Trade-Offs Regarding Fire Hazard Reduction... approved information collection, Understanding Value Trade-offs Regarding Fire Hazard Reduction Programs in...-offs Regarding Fire Hazard Reduction Programs in the Wildland-Urban Interface. OMB Number:...

  8. Job-Family Trade-offs. The Multidimensional Effects of Gender.

    ERIC Educational Resources Information Center

    Mennino, Sue Falter; Brayfield, April

    2002-01-01

    Data from 464 women and 460 men on measures of gender ideology and gender composition of occupations indicated that women and men sometimes make different job-family trade-offs. Those in male-dominated occupations made more accommodations for jobs than family. Gender attitudes had little effect on trade-offs. Family demands often operate similarly…

  9. Spatial Resolution, Grayscale, and Error Diffusion Trade-offs: Impact on Display System Design

    NASA Technical Reports Server (NTRS)

    Gille, Jennifer L. (Principal Investigator)

    1996-01-01

    We examine technology trade-offs related to grayscale resolution, spatial resolution, and error diffusion for tessellated display systems. We present new empirical results from our psychophysical study of these trade-offs and compare them to the predictions of a model of human vision.

  10. Pressure transducer system is force-balanced, has digital output

    NASA Technical Reports Server (NTRS)

    1965-01-01

    Forced-balanced pressure transducer and associated circuitry controls pressure testing of space equipment systems under actual operating conditions. The transducer and circuitry automatically converts the sensed pressure to digital form.

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed Central

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

    PubMed

    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

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

    PubMed

    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

  15. Cyber-Physical Trade-Offs in Distributed Detection Networks

    SciTech Connect

    Rao, Nageswara S; Yao, David K. Y.; Chin, J. C.; Ma, Chris Y. T.; Madan, Rabinder

    2010-01-01

    We consider a network of sensors that measure the scalar intensity due to the background or a source combined with background, inside a two-dimensional monitoring area. The sensor measurements may be random due to the underlying nature of the source and background or due to sensor errors or both. The detection problem is infer the presence of a source of unknown intensity and location based on sensor measurements. In the conventional approach, detection decisions are made at the individual sensors, which are then combined at the fusion center, for example using the majority rule. With increased communication and computation costs, we show that a more complex fusion algorithm based on measurements achieves better detection performance under smooth and non-smooth source intensity functions, Lipschitz conditions on probability ratios and a minimum packing number for the state-space. We show that these conditions for trade-offs between the cyber costs and physical detection performance are applicable for two detection problems: (i) point radiation sources amidst background radiation, and (ii) sources and background with Gaussian distributions.

  16. Anthrax Sampling and Decontamination: Technology Trade-Offs

    SciTech Connect

    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?

  17. Stress, genomic adaptation, and the evolutionary trade-off

    PubMed Central

    Horne, Steven D.; Chowdhury, Saroj K.; Heng, Henry H. Q.

    2014-01-01

    Cells are constantly exposed to various internal and external stresses. The importance of cellular stress and its implication to disease conditions have become popular research topics. Many ongoing investigations focus on the sources of stress, their specific molecular mechanisms and interactions, especially regarding their contributions to many common and complex diseases through defined molecular pathways. Numerous molecular mechanisms have been linked to endoplasmic reticulum stress along with many unexpected findings, drastically increasing the complexity of our molecular understanding and challenging how to apply individual mechanism-based knowledge in the clinic. A newly emergent genome theory searches for the synthesis of a general evolutionary mechanism that unifies different types of stress and functional relationships from a genome-defined system point of view. Herein, we discuss the evolutionary relationship between stress and somatic cell adaptation under physiological, pathological, and somatic cell survival conditions, the multiple meanings to achieve adaptation and its potential trade-off. In particular, we purposely defocus from specific stresses and mechanisms by redirecting attention toward studying underlying general mechanisms. PMID:24795754

  18. Ethanol, errors, and the speed-accuracy trade-off.

    PubMed

    Tiplady, B; Drummond, G B; Cameron, E; Gray, E; Hendry, J; Sinclair, W; Wright, P

    2001-01-01

    Ethanol has been shown to have a relatively greater effect on error rates in speeded tasks than temazepam, and this may be due to a differential effect on the speed-accuracy trade-off (SATO). This study used different instruction sets to influence the SATO. Forty-nine healthy volunteers (24 males, aged 18-41 years) were allocated at random to one of three instruction conditions--emphasising accuracy, neutral, and emphasising speed. After familiarisation, they took part in two sessions spaced at least 4 days apart in which they received either ethanol (0.8 g/kg, max 60 g males, 50 g females) or placebo in randomised order. Tests were administered starting at 30 and 75 min postdrug. Instructions significantly affected performance. In two maze tasks, one on paper, the other on a pen computer, the pattern of instruction effects was as expected. A significant increase in errors with ethanol was seen for both maze tasks, and there was a tendency to speed up with ethanol (significant only for the pen computer task). Responses to fixed stimulus sequences on the Four-Choice Reaction Test also showed a tendency to speed up and an increase in errors with ethanol, while all other tests showed both slowing and increases in errors with ethanol compared to placebo. Error scores are consistently increased by ethanol in all test situations, while the effects of ethanol on speed are variable across tests. PMID:11509226

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

    PubMed Central

    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

  20. Air quality and climate--synergies and trade-offs.

    PubMed

    von Schneidemesser, Erika; Monks, Paul S

    2013-07-01

    Air quality and climate are often treated as separate science and policy areas. Air quality encompasses the here-and-now of pollutant emissions, atmospheric transformations and their direct effect on human and ecosystem health. Climate change deals with the drivers leading to a warmer world and the consequences of that. These two science and policy issues are inexorably linked via common pollutants, such as ozone (methane) and black carbon. This short review looks at the new scientific evidence around so-called "short-lived climate forcers" and the growing realisation that a way to meet short-term climate change targets may be through the control of "air quality" pollutants. None of the options discussed here can replace reduction of long-lived greenhouse gases, such as CO2, which is required for any long-term climate change mitigation strategy. An overview is given of the underlying science, remaining uncertainties, and some of the synergies and trade-offs for addressing air quality and climate in the science and policy context. PMID:23743609

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

    NASA Technical Reports Server (NTRS)

    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.

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

    PubMed Central

    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

  3. Cadmium Protection Strategies--A Hidden Trade-Off?

    PubMed

    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

  4. Trade-offs in antibody repertoires to complex antigens

    PubMed Central

    Childs, Lauren M.; Baskerville, Edward B.; Cobey, Sarah

    2015-01-01

    Pathogens vary in their antigenic complexity. While some pathogens such as measles present a few relatively invariant targets to the immune system, others such as malaria display considerable antigenic diversity. How the immune response copes in the presence of multiple antigens, and whether a trade-off exists between the breadth and efficacy of antibody (Ab)-mediated immune responses, are unsolved problems. We present a theoretical model of affinity maturation of B-cell receptors (BCRs) during a primary infection and examine how variation in the number of accessible antigenic sites alters the Ab repertoire. Naive B cells with randomly generated receptor sequences initiate the germinal centre (GC) reaction. The binding affinity of a BCR to an antigen is quantified via a genotype–phenotype map, based on a random energy landscape, that combines local and distant interactions between residues. In the presence of numerous antigens or epitopes, B-cell clones with different specificities compete for stimulation during rounds of mutation within GCs. We find that the availability of many epitopes reduces the affinity and relative breadth of the Ab repertoire. Despite the stochasticity of somatic hypermutation, patterns of immunodominance are strongly shaped by chance selection of naive B cells with specificities for particular epitopes. Our model provides a mechanistic basis for the diversity of Ab repertoires and the evolutionary advantage of antigenically complex pathogens. PMID:26194759

  5. Resolution and noise trade-off analysis for volumetric CT

    SciTech Connect

    Li Baojun; Avinash, Gopal B.; Hsieh, Jiang

    2007-10-15

    Until recently, most studies addressing the trade-off between spatial resolution and quantum noise were performed in the context of single-slice CT. In this study, we extend the theoretical framework of previous works to volumetric CT and further extend it by taking into account the actual shapes of the preferred reconstruction kernels. In the experimental study, we also attempt to explore a three-dimensional approach for spatial resolution measurement, as opposed to the conventional two-dimensional approaches that were widely adopted in previously published studies. By scanning a finite-sized sphere phantom, the MTF was measured from the edge profile along the spherical surface. Cases of different resolutions (and noise levels) were generated by adjusting the reconstruction kernel. To reduce bias, the total photon fluxes were matched: 120 kVp, 200 mA, and 1 s per gantry rotation. All data sets were reconstructed using a modified FDK algorithm under the same condition: Scan field-of-view (SFOV)=10 cm, and slice thickness=0.625 mm. The theoretical analysis indicated that the variance of noise is proportional to >4th power of the spatial resolution. Our experimental results supported this conclusion by showing the relationship is 4.6th (helical) or 5th (axial) power.

  6. Supply-demand equilibria and the size-number trade-off in spatially structured recreational fisheries.

    PubMed

    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

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

    PubMed

    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

  8. Parasitism and Physiological Trade-Offs in Stressed Capybaras

    PubMed Central

    Eberhardt, Ayelen T.; Costa, Sebastián A.; Marini, M. Rocío; Racca, Andrea; Baldi, Cecilia J.; Robles, M. Rosario; Moreno, Pablo G.; Beldomenico, Pablo M.

    2013-01-01

    Parasites play a key role in regulating wildlife population dynamics, but their impact on the host appears to be context-dependent. Evidence indicates that a synergistic interaction between stress, host condition and parasites is implicated in this phenomenon, but more studies are needed to better understand this context-dependency. With the goal to assess the net effect of two types of chronic stress on various host-parasite interactions, we conducted an experiment in capybaras to evaluate the impact of food restriction and physical restraint on the infection intensity of specific gastrointestinal nematodes and coccidia, and how these stressors affected the growth, body condition, and some immuno-physiological parameters. Our hypothesis was that both forms of stress would result in an alteration in the host-parasite interactions, with deteriorated condition and reduced immunological investment leading to high parasite burdens and vice versa. Stressed capybaras had significantly higher coccidia infection intensities; but among individuals that were smaller, those stressed consistently showed lower helminth burdens than controls. Both stress treatments had a marked negative impact on growth and body condition, but concomitantly they had a significant positive effect on some components of the immune system. Our results suggest, on the one hand, that during prolonged periods of stress capybaras preventatively invest in some components of their immunity, such as innate humoural defenses and cells that combat helminths, which could be considered a stress-dependent prophylaxis. On the other hand, stress was found to cause greater infection intensities of protozoans but lower burdens of nematodes, indicating that the relationship between stress, physiological trade-offs and infection depends on the type of parasite in question. Moreover, both findings might be related in a causal way, as one of the immunological parameters enhanced in stressed capybaras is associated with

  9. Trading off dietary choices, physical exercise and cardiovascular disease risks.

    PubMed

    Grisolía, José M; Longo, Alberto; Boeri, Marco; Hutchinson, George; Kee, Frank

    2013-09-01

    Despite several decades of decline, cardiovascular diseases are still the most common causes of death in Western societies. Sedentary living and high fat diets contribute to the prevalence of cardiovascular diseases. This paper analyses the trade-offs between lifestyle choices defined in terms of diet, physical activity, cost, and risk of cardiovascular disease that a representative sample of the population of Northern Ireland aged 40-65 are willing to make. Using computer assisted personal interviews, we survey 493 individuals at their homes using a Discrete Choice Experiment (DCE) questionnaire administered between February and July 2011 in Northern Ireland. Unlike most DCE studies for valuing public health programmes, this questionnaire uses a tailored exercise, based on the individuals' baseline choices. A "fat screener" module in the questionnaire links personal cardiovascular disease risk to each specific choice set in terms of dietary constituents. Individuals are informed about their real status quo risk of a fatal cardiovascular event, based on an initial set of health questions. Thus, actual risks, real diet and exercise choices are the elements that constitute the choice task. Our results show that our respondents are willing to pay for reducing mortality risk and, more importantly, are willing to change physical exercise and dietary behaviours. In particular, we find that to improve their lifestyles, overweight and obese people would be more likely to do more physical activity than to change their diets. Therefore, public policies aimed to target obesity and its related illnesses in Northern Ireland should invest public money in promoting physical activity rather than healthier diets. PMID:23906130

  10. Reproduction alters oxidative status when it is traded-off against longevity.

    PubMed

    Beaulieu, Michaël; Geiger, Rina E; Reim, Elisabeth; Zielke, Luisa; Fischer, Klaus

    2015-07-01

    Oxidative stress has been proposed to mediate one of the most important aspects of life-history evolution: the trade-off between reproduction and self-maintenance. However, empirical studies have cast doubt on the generality of this intriguing notion. Here, we hypothesize that reproduction alters oxidative status only when a trade-off between reproduction and self-maintenance occurs. Accordingly, in female Bicyclus anynana butterflies, we found that reproduction affected oxidative markers only under challenging thermal conditions that made the trade-off between reproduction and longevity emerge. Interestingly, under such conditions, butterflies favored longevity over reproduction, suggesting that self-maintenance mechanisms were activated. Accordingly, butterflies reproducing under challenging thermal conditions exhibited enhanced antioxidant defenses and stable oxidative damage. Altogether, our results indicate that a trade-off between reproduction and self-maintenance is indeed a necessary condition for reproduction to alter oxidative status, and that the effects of such a trade-off on oxidative status depend on whether priority is given to self-maintenance or reproduction. Assessing the existence of the trade-off between self-maintenance and reproduction, and whether self-maintenance is prioritized relative to reproduction is therefore crucial for understanding variation in oxidative status in reproducing animals, which may clarify the general implication of oxidative stress in the resolution of life-history trade-offs. PMID:26095834

  11. Insights from life history theory for an explicit treatment of trade-offs in conservation biology.

    PubMed

    Charpentier, Anne

    2015-06-01

    As economic and social contexts become more embedded within biodiversity conservation, it becomes obvious that resources are a limiting factor in conservation. This recognition is leading conservation scientists and practitioners to increasingly frame conservation decisions as trade-offs between conflicting societal objectives. However, this framing is all too often done in an intuitive way, rather than by addressing trade-offs explicitly. In contrast, the concept of trade-off is a keystone in evolutionary biology, where it has been investigated extensively. I argue that insights from evolutionary theory can provide methodological and theoretical support to evaluating and quantifying trade-offs in biodiversity conservation. I reviewed the diverse ways in which trade-offs have emerged within the context of conservation and how advances from evolutionary theory can help avoid the main pitfalls of an implicit approach. When studying both evolutionary trade-offs (e.g., reproduction vs. survival) and conservation trade-offs (e.g., biodiversity conservation vs. agriculture), it is crucial to correctly identify the limiting resource, hold constant the amount of this resource when comparing different scenarios, and choose appropriate metrics to quantify the extent to which the objectives have been achieved. Insights from studies in evolutionary theory also reveal how an inadequate selection of conservation solutions may result from considering suboptimal rather than optional solutions when examining whether a trade-off exits between 2 objectives. Furthermore, the shape of a trade-off curve (i.e., whether the relationship between 2 objectives follows a concave, convex, or linear form) is known to affect crucially the definition of optimal solutions in evolutionary biology and very likely affects decisions in biodiversity conservation planning too. This interface between evolutionary biology and biodiversity conservation can therefore provide methodological guidance to

  12. Competing values, tensions and trade-offs in management of nuclear power plants.

    PubMed

    Reiman, Teemu; Rollenhagen, Carl

    2012-01-01

    The specific goal of the study is to look how tensions, competing values and trade-offs manifest in the management of nuclear power plants. Second goal is to inspect how existing frameworks, such as Competing Values Framework, can be used to model the tensions. Empirical data consists of thirty interviews that were conducted as part of a NKS study on safety culture in the Nordic nuclear branch. Eight trade-offs are identified based on a grounded theory based analysis of the interview data. The competing values and potential tensions involved in the trade-offs are discussed. PMID:22316807

  13. Age Differences in Trade-Off Decisions: Older Adults Prefer Choice Deferral

    PubMed Central

    Chen, Yiwei; Ma, Xiaodong; Pethtel, Olivia

    2014-01-01

    Our primary purpose in this study was to examine age differences in using choice deferral when young and older adults made trade-off decisions. Ninety-two young and 92 older adults were asked to make a trade-off decision among four cars or to use choice deferral (i.e., not buy any of these cars and keep looking for other cars). High and low emotional trade-off difficulty were manipulated between participants through different attribute labels of available cars. Older adults were more likely than young adults to choose deferral. Older adults who used deferral reported less retrospective negative emotion than those who did not. PMID:21534690

  14. Flowering schedule in a perennial plant; life-history trade-offs, seed predation, and total offspring fitness.

    PubMed

    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

  15. Nutritional and non-nutritional food components modulate phenotypic variation but not physiological trade-offs in an insect.

    PubMed

    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

  16. Nutritional and non-nutritional food components modulate phenotypic variation but not physiological trade-offs in an insect

    PubMed Central

    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

  17. Competition and predation in simple food webs: intermediately strong trade-offs maximize coexistence.

    PubMed Central

    HilleRisLambers, Reinier; Dieckmann, Ulf

    2003-01-01

    Competition and predation are fundamental interactions structuring food webs. However, rather than always following these neat theoretical categories, mixed interactions are ubiquitous in nature. Of particular importance are omnivorous species, such as intra-guild predators that can both compete with and predate on their prey. Here, we examine trade-offs between competitive and predatory capacities by analysing the entire continuum of food web configurations existing between purely predator-prey and purely competitive interactions of two consumers subsisting on a single resource. Our results show that the range of conditions allowing for coexistence of the consumers is maximized at intermediately strong trade-offs. Even though coexistence under weak trade-offs and under very strong trade-offs is also possible, it occurs under much more restrictive conditions. We explain these findings by an intricate interplay between energy acquisition and interaction strength. PMID:14728782

  18. The adaptive trade-off between detection and discrimination in cortical representations and behavior

    PubMed Central

    Ollerenshaw, Douglas R.; Zheng, He J. V.; Millard, Daniel C.; Wang, Qi; Stanley, Garrett B.

    2014-01-01

    SUMMARY It has long been posited that detectability of sensory inputs can be sacrificed in favor of improved discriminability, and that sensory adaptation may mediate this trade-off. The extent to which this trade-off exists behaviorally, and the complete picture of the underlying neural representations that likely subserve the phenomenon, remain unclear. In the rodent vibrissa system, an ideal observer analysis of cortical activity measured using voltage sensitive dye (VSD) imaging in anesthetized animals was combined with behavioral detection and discrimination tasks, thalamic recordings from awake animals, and computational modeling to show that spatial discrimination performance was improved following adaptation, but at the expense of the ability to detect weak stimuli. Together, these results provide direct behavioral evidence for the trade-off between detectability and discriminability, that this trade-off can be modulated through bottom-up sensory adaptation, and that these effects correspond to important changes in thalamocortical coding properties. PMID:24607233

  19. The trade-off between food and temperature in the habitat choice of bluegill sunfish

    USGS Publications Warehouse

    Wildhaber, M.L.

    2001-01-01

    A model is presented to describe the trade-off between food and temperature in bluegills Lepomis macrochirus, where temperature was the primary factor used in determining the patch in which to reside.

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

    PubMed

    Norheim, Ole Frithjof

    2015-01-01

    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. PMID:26673330

  1. Research a Novel Integrated and Dynamic Multi-object Trade-Off Mechanism in Software Project

    NASA Astrophysics Data System (ADS)

    Jiang, Weijin; Xu, Yuhui

    Aiming at practical requirements of present software project management and control, the paper presented to construct integrated multi-object trade-off model based on software project process management, so as to actualize integrated and dynamic trade-oil of the multi-object system of project. Based on analyzing basic principle of dynamic controlling and integrated multi-object trade-off system process, the paper integrated method of cybernetics and network technology, through monitoring on some critical reference points according to the control objects, emphatically discussed the integrated and dynamic multi- object trade-off model and corresponding rules and mechanism in order to realize integration of process management and trade-off of multi-object system.

  2. Risk/Requirements Trade-off Guidelines for Low Cost Satellite Systems

    NASA Technical Reports Server (NTRS)

    Cornford, Steven L.; Man, Kin F.

    1996-01-01

    The accelerating trend toward faster, better, cheaper missions places increasing emphasis on the trade-offs between requirements and risk to reduce cost and development times, while still improving quality and reliability. The Risk/Requirement Trade-off Guidelines discussed in this paper are part of an integrated approach to address the main issues by focusing on the sum of prevention, analysis, control, or test (PACT) processes.

  3. SIRT1 and Caloric Restriction: An Insight Into Possible Trade-Offs Between Robustness and Frailty

    PubMed Central

    Imai, Shin-ichiro

    2009-01-01

    Purpose of review This review aims to summarize the importance of the mammalian NAD-dependent deacetylase SIRT1 as a critical mediator that coordinates metabolic responses to caloric restriction (CR) and the recent progress in the development of SIRT1-targeted CR mimetics. It also discusses possible trade-offs between robustness and frailty in CR and the applicability of CR or SIRT1-targeted CR mimetics to humans. Recent findings Loss- and gain-of-function mouse studies have provided genetic evidence that SIRT1 is a key mediator that orchestrates the physiological response to CR. SIRT1-activating compounds function as potential CR mimetics, at least in part, through the activation of SIRT1 in vivo. Summary Increasing SIRT1 dosage/activity is effective to provide significant protection from high-fat diet-induced metabolic complications, suggesting that SIRT1 activation likely promotes robustness in the regulation of metabolism. However, CR itself and CR mimicry through systemic SIRT1 activation might also generate frailty in response to unexpected environmental stimuli, such as bacterial and viral infections. It will be of great importance to understand the principles of systemic robustness and its spatial and temporal dynamics for the regulation of aging and longevity in mammals in order to achieve an optimal balance between robustness and frailty in our complex physiological system. PMID:19474721

  4. Daily foraging patterns in free-living birds: exploring the predation–starvation trade-off

    PubMed Central

    Bonter, David N.; Zuckerberg, Benjamin; Sedgwick, Carolyn W.; Hochachka, Wesley M.

    2013-01-01

    Daily patterns in the foraging behaviour of birds are assumed to balance the counteracting risks of predation and starvation. Predation risks are a function of the influence of weight on flight performance and foraging behaviours that may expose individuals to predators. Although recent research sheds light on daily patterns in weight gain, little data exist on daily foraging routines in free-living birds. In order to test the predictions of various hypotheses about daily patterns of foraging, we quantified the activity of four species of passerines in winter using radio-frequency identification receivers built into supplemental feeding stations. From records of 472 368 feeder visits by tagged birds, we found that birds generally started to feed before sunrise and continued to forage at a steady to increasing rate throughout the day. Foraging in most species terminated well before sunset, suggesting their required level of energy reserves was being reached before the end of the day. These results support the risk-spreading theorem over a long-standing hypothesis predicting bimodality in foraging behaviour purportedly driven by a trade-off between the risks of starvation and predation. Given the increased energetic demands experienced by birds during colder weather, our results suggest that birds' perceptions of risk are biased towards starvation avoidance in winter. PMID:23595267

  5. Biofuels from pyrolysis in perspective: trade-offs between energy yields and soil-carbon additions.

    PubMed

    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. PMID:24787482

  6. Trade-Offs Between Biodiversity Conservation and Economic Development in Five Tropical Forest Landscapes

    NASA Astrophysics Data System (ADS)

    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.

  7. Brevity and speed of message delivery trade-offs in augmentative and alternative communication.

    PubMed

    McCoy, Kathleen F; Bedrosian, Jan L; Hoag, Linda A; Johnson, Dallas E

    2007-03-01

    This study is the third in a series of studies that have concentrated on utterance-based systems--which allow the relatively quick selection of full sentences--and investigated trade-offs faced by users of such systems when there is a pragmatic mismatch between the prestored sentence and the current discourse context. While the previous studies focused on trade-offs between speed of message delivery and either relevance or informativeness, this study investigated the effects of trade-offs between speed of message delivery and brevity on public attitudes. Participating were 96 sales clerks who viewed scripted, videotaped trade-off message conditions in the context of a bookstore interaction and completed a questionnaire designed to assess their attitudes toward customers who used utterance-based systems and his or her communication. Significantly higher mean ratings were found for the trade-off condition involving the quickly delivered message with repetition when compared to each of the slowly delivered, non-repetitive message conditions (i.e., with and without a preceding conversational floorholder). Implications regarding the model of conversational trade-off choices and its technological applications are discussed. PMID:17364489

  8. Trade-offs Between Electricity Production from Small Hydropower Plants and Ecosystem Services in Alpine River Basins

    NASA Astrophysics Data System (ADS)

    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

  9. Trade-offs and coexistence in fluctuating environments: evidence for a key dispersal-fecundity trade-off in five nonpollinating fig wasps.

    PubMed

    Duthie, A Bradley; Abbott, Karen C; Nason, John D

    2015-07-01

    The ecological principle of competitive exclusion states that species competing for identical resources cannot coexist, but this principle is paradoxical because ecologically similar competitors are regularly observed. Coexistence is possible under some conditions if a fluctuating environment changes the competitive dominance of species. This change in competitive dominance implies the existence of trade-offs underlying species' competitive abilities in different environments. Theory shows that fluctuating distance between resource patches can facilitate coexistence in ephemeral patch competitors, given a functional trade-off between species dispersal ability and fecundity. We find evidence supporting this trade-off in a guild of five ecologically similar nonpollinating fig wasps and subsequently predict local among-patch species densities. We also introduce a novel colonization index to estimate relative dispersal ability among ephemeral patch competitors. We suggest that a dispersal ability-fecundity trade-off and spatiotemporally fluctuating resource availability commonly co-occur to drive population dynamics and facilitate coexistence in ephemeral patch communities. PMID:26098346

  10. Decoupling speed and accuracy in an urgent decision-making task reveals multiple contributions to their trade-off

    PubMed Central

    Salinas, Emilio; Scerra, Veronica E.; Hauser, Christopher K.; Costello, M. Gabriela; Stanford, Terrence R.

    2014-01-01

    A key goal in the study of decision making is determining how neural networks involved in perception and motor planning interact to generate a given choice, but this is complicated due to the internal trade-off between speed and accuracy, which confounds their individual contributions. Urgent decisions, however, are special: they may range between random and fully informed, depending on the amount of processing time (or stimulus viewing time) available in each trial, but regardless, movement preparation always starts early on. As a consequence, under time pressure it is possible to produce a psychophysical curve that characterizes perceptual performance independently of reaction time, and this, in turn, makes it possible to pinpoint how perceptual information (which requires sensory input) modulates motor planning (which does not) to guide a choice. Here we review experiments in which, on the basis of this approach, the origin of the speed-accuracy trade-off becomes particularly transparent. Psychophysical, neurophysiological, and modeling results in the “compelled-saccade” task indicate that, during urgent decision making, perceptual information—if and whenever it becomes available—accelerates or decelerates competing motor plans that are already ongoing. This interaction affects both the reaction time and the probability of success in any given trial. In two experiments with reward asymmetries, we find that speed and accuracy can be traded in different amounts and for different reasons, depending on how the particular task contingencies affect specific neural mechanisms related to perception and motor planning. Therefore, from the vantage point of urgent decisions, the speed-accuracy trade-off is not a unique phenomenon tied to a single underlying mechanism, but rather a typical outcome of many possible combinations of internal adjustments within sensory-motor neural circuits. PMID:24795559

  11. Temperature effects in supercritical fluid chromatography: a trade-off between viscous heating and decompression cooling.

    PubMed

    De Pauw, Ruben; Choikhet, Konstantin; Desmet, Gert; Broeckhoven, Ken

    2014-10-24

    The study of radial and axial temperature profiles always has been an area interest both in liquid chromatography (LC) and supercritical fluid chromatography (SFC). Whereas in LC always an increase in temperature is observed due to the dominance of viscous heating, in SFC, especially for low modifier content, a decrease in temperature is found due to the much larger decompression cooling. However, for higher modifier content and higher operating pressure, the temperature effects become a trade-off between viscous heating and decompression cooling, since in SFC the latter is a strong function of operating pressure and mobile phase composition. At a temperature of 40°C and for neat CO2, the effect of decompression cooling and viscous heating cancel each other out at a pressure 450bar. This pressure decreases almost linearly with volume fraction of methanol to 150bar at 25vol%. As a result, both cooling and heating effects can be observed when operating at high back pressure, large column pressure drops or high modifier content. For example at a back pressure of 150bar and a column pressure drop of 270bar decompression cooling is observed throughout the column. However at 300bar back pressure and the same pressure drop, the mobile phase heats up in the first part of the column due to viscous heating and then cools in the second part due to decompression cooling. When coupling columns (2.1mm×150mm, 1.8μm fully porous particles) at very high operating pressure (e.g. 750bar for 8vol%), the situation is even more complex. E.g. at a back pressure of 150bar and using 8vol% methanol, viscous heating is only observed in the first column whereas only decompression cooling in the second. Further increasing the inlet pressure up to 1050bar resulted in no excessive temperature differences along the column. This implies that the inlet pressure of SFC instrumentation could be expanded above 600bar without additional band broadening caused by excessive radial temperature

  12. Caught between two Allee effects: trade-off between reproduction and predation risk.

    PubMed

    Pavlová, Viola; Berec, Ludĕk; Boukal, David S

    2010-06-01

    Reproductive activities are often associated with conspicuous morphology or behaviour that could be exploited by predators. Individuals can therefore face a trade-off between reproduction and predation risk. Here we use simple models to explore population-dynamical consequences of such a trade-off for populations subject to a mate-finding Allee effect and an Allee effect due to predation. We present our results in the light of populations that belong to endangered species or pests and study their viability and resilience. We distinguish several qualitative scenarios characterized by the shape and strength of the trade-off and, in particular, identify conditions for which the populations survive or go extinct. Reproduction can be so costly that the population always goes extinct. In other cases, the population goes extinct only over a certain range of low, intermediate or high levels of reproductive activities. Moreover, we show that predator removal (e.g. in an attempt to save an endangered prey species) has the least effect on populations with low cost of reproduction in terms of predation and, conversely, predator addition (e.g. to eradicate a pest) is most effective for populations with high predation cost of reproduction. Our results indicate that a detailed knowledge of the trade-off can be crucial in applications: for some trade-off shapes, only intermediate levels of reproductive activities might guarantee population survival, while they can lead to extinction for others. We therefore suggest that the fate of populations subject to the two antagonistic Allee effects should be evaluated on a case-by-case basis. Although the literature offers no quantitative data on possible trade-off shapes in any taxa, indirect evidence suggests that the trade-off and both Allee effects can occur simultaneously, e.g. in the golden egg bug Phyllomorpha laciniata. PMID:20227422

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

    PubMed Central

    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

  14. Trade-off between Intensity and Frequency of Global Tropical Cyclones

    NASA Astrophysics Data System (ADS)

    Kang, N. Y.; Elsner, J.

    2015-12-01

    Global tropical cyclone climate has been investigated with indicators of frequency, intensity and activity. However, a full understanding of global warming's influence on tropical cyclone climate remains elusive because of the incomplete nature of these indicators. Here we form a complete three-dimensional variability space of tropical cyclone climate where the variabilities are continuously linked and find that global ocean warmth best explains the out-of-phase relationship between intensity and frequency of global tropical cyclones. In a year with greater ocean warmth, the tropical troposphere is capped by higher pressure anomaly in the middle and upper troposphere even with higher moist static energy anomaly in the lower troposphere, which is thought to inhibit overall tropical cyclone occurrences but lead to greater intensities. Statistical consequence is the trade-off between intensity and frequency. We calculate an average increase in global tropical cyclone intensity of 1.3 m/s over the past 30 years of ocean warming occurring at the expense of 6.1 tropical cyclones worldwide.

  15. Trade-Off between Thermal Link Solutions for the Cryosystem Cryocooler On-Board the International Space Station

    NASA Astrophysics Data System (ADS)

    Trollier, T.; Ravex, A.; Aubry, C.; Seidel, A.; Stephan, H.; De Parolis, L.; Sirbi, A.; Kujala, R.

    2004-06-01

    AL/DTA has been selected by EADS in February 2002 for the delivery of the vial freezer for the ESA / CRYOSYSTEM project. CRYOSYSTEM is a set of facilities for ultra-rapid cooling, preservation and storage of biological samples and protein crystals at -180°C on-board the ISS. Flexure bearing Stirling cryocoolers from THALES are used to cool down the dewar storage magazine of the vial freezers. We present here some elements of the trade-offs performed between two potential solutions for the thermal link between the Stirling cold finger and the dewar magazine. The two solutions envisaged were a conventional Braids Thermal Link Assembly (BTLA) and an original Liquid Thermal Link Assembly (LTLA). The BTLA makes use of flexible copper braids, while the LTLA is based on an evaporation/condensation process of an appropriate fluid between the cold finger and the cold magazine. The trade-off is based on thermal and mechanical tests results performed on both links, combined with system impact analysis such as implementation, added parasitic heat losses and safety considerations for pressurized payloads on-board the International Space Station.

  16. Patterns of sperm damage in Chernobyl passerine birds suggest a trade-off between sperm length and integrity

    PubMed Central

    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, presumably resulting from chronic irradiation following the 1986 accident. Frequencies of sperm abnormalities varied between 15.7 and 77.3% among species, more than fourfold higher than in uncontaminated areas. Nonetheless, species ranked similarly in sperm abnormalities in unpolluted areas as in Chernobyl, pointing to intrinsic factors underlying variation in sperm damage among species. Scanning electron microscopy of abnormal spermatozoa revealed patterns of acrosome damage consistent with premature acrosome reaction. Sperm length, but not sperm competition risk explained variation in sperm damage among species. This suggests that longer spermatozoa are more susceptible to premature acrosome reaction. Therefore, we hypothesize a trade-off between sperm length and sperm integrity affecting sperm evolution in passerine birds. PMID:24088561

  17. Geographic variations of life history traits and potential trade-offs in different populations of the parasitoid Leptopilina heterotoma

    NASA Astrophysics Data System (ADS)

    Vuarin, Pauline; Allemand, Roland; Moiroux, Joffrey; van Baaren, Joan; Gibert, Patricia

    2012-11-01

    Energy allocation is determined by resource availability and trade-offs among traits, and so organisms have to give some traits priority over others to maximize their fitness according to their environment. In this study, we investigated the geographic variations in life history traits and potential trade-offs in populations of the parasitoid Leptopilina heterotoma (Hymenoptera: Figitidae) originating from the north and the south of the Rhône-Saône valley (over a gradient of 300 km, South-East France). We measured a set of traits related to reproduction, maintenance, and mobility using several estimators of each of these main functions determined at different times. We did not find any clear differences between populations from contrasting areas, whereas the southern populations, which were all assumed to be exposed to similar environmental conditions, displayed contrasting patterns of energy allocation. Thus, the most likely explanation seems to be that the evolution of the life history of L. heterotoma is probably shaped by local selective pressures, such as microclimate, microhabitats, or intensity of competition, rather than by regional ecological conditions. Using our study as an example, we discuss the interest of considering several traits and using different ways of measuring them, concluding that multiple measurements should be performed in future studies to ensure the robustness of the results.

  18. Geographic variations of life history traits and potential trade-offs in different populations of the parasitoid Leptopilina heterotoma.

    PubMed

    Vuarin, Pauline; Allemand, Roland; Moiroux, Joffrey; van Baaren, Joan; Gibert, Patricia

    2012-11-01

    Energy allocation is determined by resource availability and trade-offs among traits, and so organisms have to give some traits priority over others to maximize their fitness according to their environment. In this study, we investigated the geographic variations in life history traits and potential trade-offs in populations of the parasitoid Leptopilina heterotoma (Hymenoptera: Figitidae) originating from the north and the south of the Rhône-Saône valley (over a gradient of 300 km, South-East France). We measured a set of traits related to reproduction, maintenance, and mobility using several estimators of each of these main functions determined at different times. We did not find any clear differences between populations from contrasting areas, whereas the southern populations, which were all assumed to be exposed to similar environmental conditions, displayed contrasting patterns of energy allocation. Thus, the most likely explanation seems to be that the evolution of the life history of L. heterotoma is probably shaped by local selective pressures, such as microclimate, microhabitats, or intensity of competition, rather than by regional ecological conditions. Using our study as an example, we discuss the interest of considering several traits and using different ways of measuring them, concluding that multiple measurements should be performed in future studies to ensure the robustness of the results. PMID:23052821

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

    PubMed

    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

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

    PubMed Central

    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. Signal diversification in Oecanthus tree crickets is shaped by energetic, morphometric, and acoustic trade-offs.

    PubMed

    Symes, L B; Ayres, M P; Cowdery, C P; Costello, R A

    2015-06-01

    Physiology, physics, and ecological interactions can generate trade-offs within species, but may also shape divergence among species. We tested whether signal divergence in Oecanthus tree crickets is shaped by acoustic, energetic, and behavioral trade-offs. We found that species with faster pulse rates, produced by opening and closing wings up to twice as many times per second, did not have higher metabolic costs of calling. The relatively constant energetic cost across species is explained by trade-offs between the duration and repetition rate of acoustic signals-species with fewer stridulatory teeth closed their wings more frequently such that the number of teeth struck per second of calling and the resulting duty cycle were relatively constant across species. Further trade-offs were evident in relationships between signals and body size. Calling was relatively inexpensive for small males, permitting them to call for much of the night, but at low amplitude. Large males produced much louder calls, reaching up to four times more area, but the energetic costs increased substantially with increasing size and the time spent calling dropped to only 20% of the night. These trade-offs indicate that the trait combinations that arise in these species represent a limited subset of conceivable trait combinations. PMID:25903317

  2. Trade-offs shape the evolution of the vector-borne insect pathogen Xenorhabdus nematophila.

    PubMed

    Chapuis, Elodie; Arnal, Audrey; Ferdy, Jean-Baptiste

    2012-07-01

    Our current understanding on how pathogens evolve relies on the hypothesis that pathogens' transmission is traded off against host exploitation. In this study, we surveyed the possibility that trade-offs determine the evolution of the bacterial insect pathogen, Xenorhabdus nematophila. This bacterium rapidly kills the hosts it infects and is transmitted from host cadavers to new insects by a nematode vector, Steinernema carpocapsae. In order to detect trade-offs in this biological system, we produced 20 bacterial lineages using an experimental evolution protocol. These lineages differ, among other things, in their virulence towards the insect host. We found that nematode parasitic success increases with bacteria virulence, but their survival during dispersal decreases with the number of bacteria they carry. Other bacterial traits, such as production of the haemolytic protein XaxAB, have a strong impact on nematode reproduction. We then combined the result of our measurements with an estimate of bacteria fitness, which was divided into a parasitic component and a dispersal component. Contrary to what was expected in the trade-off hypothesis, we found no significant negative correlation between the two components of bacteria fitness. Still, we found that bacteria fitness is maximized when nematodes carry an intermediate number of cells. Our results therefore demonstrate the existence of a trade-off in X. nematophila, which is caused, in part, by the reduction in survival this bacterium causes to its nematode vectors. PMID:22398163

  3. Trade-offs shape the evolution of the vector-borne insect pathogen Xenorhabdus nematophila

    PubMed Central

    Chapuis, Élodie; Arnal, Audrey; Ferdy, Jean-Baptiste

    2012-01-01

    Our current understanding on how pathogens evolve relies on the hypothesis that pathogens' transmission is traded off against host exploitation. In this study, we surveyed the possibility that trade-offs determine the evolution of the bacterial insect pathogen, Xenorhabdus nematophila. This bacterium rapidly kills the hosts it infects and is transmitted from host cadavers to new insects by a nematode vector, Steinernema carpocapsae. In order to detect trade-offs in this biological system, we produced 20 bacterial lineages using an experimental evolution protocol. These lineages differ, among other things, in their virulence towards the insect host. We found that nematode parasitic success increases with bacteria virulence, but their survival during dispersal decreases with the number of bacteria they carry. Other bacterial traits, such as production of the haemolytic protein XaxAB, have a strong impact on nematode reproduction. We then combined the result of our measurements with an estimate of bacteria fitness, which was divided into a parasitic component and a dispersal component. Contrary to what was expected in the trade-off hypothesis, we found no significant negative correlation between the two components of bacteria fitness. Still, we found that bacteria fitness is maximized when nematodes carry an intermediate number of cells. Our results therefore demonstrate the existence of a trade-off in X. nematophila, which is caused, in part, by the reduction in survival this bacterium causes to its nematode vectors. PMID:22398163

  4. Telecommuting: The Trade-Offs of Home Work.

    ERIC Educational Resources Information Center

    Kraut, Robert E.

    1989-01-01

    Reports that relatively few people use their home as a primary work site and that those who do (substitutors, self-employed, and supplementers) balance their needs for employment flexibility against their needs for income. Discusses differing motivations and satisfactions, and the wage gap between home workers and conventional workers. (SR)

  5. Trade-off between the Mechanical Strength and Microwave Electrical Properties of Functionalized and Irradiated Carbon Nanotube Sheets.

    PubMed

    Williams, Tiffany S; Orloff, Nathan D; Baker, James S; Miller, Sandi G; Natarajan, Bharath; Obrzut, Jan; McCorkle, Linda S; Lebron-Colón, Marisabel; Gaier, James; Meador, Michael A; Liddle, J Alexander

    2016-04-13

    Carbon nanotube (CNT) sheets represent a novel implementation of CNTs that enable the tailoring of electrical and mechanical properties for applications in the automotive and aerospace industries. Small molecule functionalization and postprocessing techniques, such as irradiation with high-energy particles, are methods that can enhance the mechanical properties of CNTs. However, the effect that these modifications have on the electrical conduction mechanisms has not been extensively explored. By characterizing the mechanical and electrical properties of multiwalled carbon nanotube (MWCNT) sheets with different functional groups and irradiation doses, we can expand our insights into the extent of the trade-off that exists between mechanical strength and electrical conductivity for commercially available CNT sheets. Such insights allow for the optimization of design pathways for engineering applications that require a balance of material property enhancements. PMID:27044063

  6. Evolutionary trade-offs, Pareto optimality, and the geometry of phenotype space.

    PubMed

    Shoval, O; Sheftel, H; Shinar, G; Hart, Y; Ramote, O; Mayo, A; Dekel, E; Kavanagh, K; Alon, U

    2012-06-01

    Biological systems that perform multiple tasks face a fundamental trade-off: A given phenotype cannot be optimal at all tasks. Here we ask how trade-offs affect the range of phenotypes found in nature. Using the Pareto front concept from economics and engineering, we find that best-trade-off phenotypes are weighted averages of archetypes--phenotypes specialized for single tasks. For two tasks, phenotypes fall on the line connecting the two archetypes, which could explain linear trait correlations, allometric relationships, as well as bacterial gene-expression patterns. For three tasks, phenotypes fall within a triangle in phenotype space, whose vertices are the archetypes, as evident in morphological studies, including on Darwin's finches. Tasks can be inferred from measured phenotypes based on the behavior of organisms nearest the archetypes. PMID:22539553

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

    PubMed

    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. Evolutionary trade-offs in plants mediate the strength of trophic cascades.

    PubMed

    Mooney, Kailen A; Halitschke, Rayko; Kessler, Andre; Agrawal, Anurag A

    2010-03-26

    Predators determine herbivore and plant biomass via so-called trophic cascades, and the strength of such effects is influenced by ecosystem productivity. To determine whether evolutionary trade-offs among plant traits influence patterns of trophic control, we manipulated predators and soil fertility and measured impacts of a major herbivore (the aphid Aphis nerii) on 16 milkweed species (Asclepias spp.) in a phylogenetic field experiment. Herbivore density was determined by variation in predation and trade-offs between herbivore resistance and plant growth strategy. Neither herbivore density nor predator effects on herbivores predicted the cascading effects of predators on plant biomass. Instead, cascade strength was strongly and positively associated with milkweed response to soil fertility. Accordingly, contemporary patterns of trophic control are driven by evolutionary convergent trade-offs faced by plants. PMID:20339073

  9. Trade-off relations of Bell violations among pairwise qubit systems

    NASA Astrophysics Data System (ADS)

    Qin, Hui-Hui; Fei, Shao-Ming; Li-Jost, Xianqing

    2015-12-01

    We investigate the nonlocality distributions among multiqubit systems based on the maximal violations of the Clauser-Horne-Shimony-Holt (CHSH) inequality of reduced pairwise qubit systems. We present a trade-off relation satisfied by these maximal violations, which gives rise to restrictions on the distribution of nonlocality among the subqubit systems. For a three-qubit system, it is impossible that all pairs of qubits violate the CHSH inequality, and once a pair of qubits violates the CHSH inequality maximally, the other two pairs of qubits must both obey the CHSH inequality. Detailed examples are given to illustrate the trade-off relations, and the trade-off relations are generalized to arbitrary multiqubit systems.

  10. Evolution of dispersal under a fecundity-dispersal trade-off.

    PubMed

    Weigang, Helene C; Kisdi, Éva

    2015-04-21

    Resources invested in dispersal structures as well as time and energy spent during transfer may often decrease fecundity. Here we analyse an extended version of the Hamilton-May model of dispersal evolution, where we include a fecundity-dispersal trade-off and also mortality between competition and reproduction. With adaptive dynamics and critical function analysis we investigate the evolution of dispersal strategies and ask whether adaptive diversification is possible. We exclude evolutionary branching for concave trade-offs and show that for convex trade-offs diversification is promoted in a narrow parameter range. We provide theoretical evidence that dispersal strategies can monotonically decrease with increasing survival during dispersal. Moreover, we illustrate the existence of two alternative attracting dispersal strategies. The model exhibits fold bifurcation points where slight changes in survival can lead to evolutionary catastrophes. PMID:25702937

  11. Cancer susceptibility and reproductive trade-offs: a model of the evolution of cancer defences.

    PubMed

    Boddy, Amy M; Kokko, Hanna; Breden, Felix; Wilkinson, Gerald S; Aktipis, C Athena

    2015-07-19

    The factors influencing cancer susceptibility and why it varies across species are major open questions in the field of cancer biology. One underexplored source of variation in cancer susceptibility may arise from trade-offs between reproductive competitiveness (e.g. sexually selected traits, earlier reproduction and higher fertility) and cancer defence. We build a model that contrasts the probabilistic onset of cancer with other, extrinsic causes of mortality and use it to predict that intense reproductive competition will lower cancer defences and increase cancer incidence. We explore the trade-off between cancer defences and intraspecific competition across different extrinsic mortality conditions and different levels of trade-off intensity, and find the largest effect of competition on cancer in species where low extrinsic mortality combines with strong trade-offs. In such species, selection to delay cancer and selection to outcompete conspecifics are both strong, and the latter conflicts with the former. We discuss evidence for the assumed trade-off between reproductive competitiveness and cancer susceptibility. Sexually selected traits such as ornaments or large body size require high levels of cell proliferation and appear to be associated with greater cancer susceptibility. Similar associations exist for female traits such as continuous egg-laying in domestic hens and earlier reproductive maturity. Trade-offs between reproduction and cancer defences may be instantiated by a variety of mechanisms, including higher levels of growth factors and hormones, less efficient cell-cycle control and less DNA repair, or simply a larger number of cell divisions (relevant when reproductive success requires large body size or rapid reproductive cycles). These mechanisms can affect intra- and interspecific variation in cancer susceptibility arising from rapid cell proliferation during reproductive maturation, intrasexual competition and reproduction. PMID:26056364

  12. Cancer susceptibility and reproductive trade-offs: a model of the evolution of cancer defences

    PubMed Central

    Boddy, Amy M.; Kokko, Hanna; Breden, Felix; Wilkinson, Gerald S.; Aktipis, C. Athena

    2015-01-01

    The factors influencing cancer susceptibility and why it varies across species are major open questions in the field of cancer biology. One underexplored source of variation in cancer susceptibility may arise from trade-offs between reproductive competitiveness (e.g. sexually selected traits, earlier reproduction and higher fertility) and cancer defence. We build a model that contrasts the probabilistic onset of cancer with other, extrinsic causes of mortality and use it to predict that intense reproductive competition will lower cancer defences and increase cancer incidence. We explore the trade-off between cancer defences and intraspecific competition across different extrinsic mortality conditions and different levels of trade-off intensity, and find the largest effect of competition on cancer in species where low extrinsic mortality combines with strong trade-offs. In such species, selection to delay cancer and selection to outcompete conspecifics are both strong, and the latter conflicts with the former. We discuss evidence for the assumed trade-off between reproductive competitiveness and cancer susceptibility. Sexually selected traits such as ornaments or large body size require high levels of cell proliferation and appear to be associated with greater cancer susceptibility. Similar associations exist for female traits such as continuous egg-laying in domestic hens and earlier reproductive maturity. Trade-offs between reproduction and cancer defences may be instantiated by a variety of mechanisms, including higher levels of growth factors and hormones, less efficient cell-cycle control and less DNA repair, or simply a larger number of cell divisions (relevant when reproductive success requires large body size or rapid reproductive cycles). These mechanisms can affect intra- and interspecific variation in cancer susceptibility arising from rapid cell proliferation during reproductive maturation, intrasexual competition and reproduction. PMID:26056364

  13. Pressure balanced drag turbine mass flow meter

    DOEpatents

    Dacus, M.W.; Cole, J.H.

    1980-04-23

    The density of the fluid flowing through a tubular member may be measured by a device comprising a rotor assembly suspended within the tubular member, a fluid bearing medium for the rotor assembly shaft, independent fluid flow lines to each bearing chamber, and a scheme for detection of any difference between the upstream and downstream bearing fluid pressures. The rotor assembly reacts to fluid flow both by rotation and axial displacement; therefore concurrent measurements may be made of the velocity of blade rotation and also bearing pressure changes, where the pressure changes may be equated to the fluid momentum flux imparted to the rotor blades. From these parameters the flow velocity and density of the fluid may be deduced.

  14. Pressure balanced drag turbine mass flow meter

    DOEpatents

    Dacus, Michael W.; Cole, Jack H.

    1982-01-01

    The density of the fluid flowing through a tubular member may be measured by a device comprising a rotor assembly suspended within the tubular member, a fluid bearing medium for the rotor assembly shaft, independent fluid flow lines to each bearing chamber, and a scheme for detection of any difference between the upstream and downstream bearing fluid pressures. The rotor assembly reacts to fluid flow both by rotation and axial displacement; therefore concurrent measurements may be made of the velocity of blade rotation and also bearing pressure changes, where the pressure changes may be equated to the fluid momentum flux imparted to the rotor blades. From these parameters the flow velocity and density of the fluid may be deduced.

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

    PubMed

    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

  16. How Porin Heterogeneity and Trade-Offs Affect the Antibiotic Susceptibility of Gram-Negative Bacteria

    PubMed Central

    Ferenci, Thomas; Phan, Katherine

    2015-01-01

    Variations in porin proteins are common in Gram-negative pathogens. Altered or absent porins reduce access of polar antibiotics across the outer membrane and can thus contribute to antibiotic resistance. Reduced permeability has a cost however, in lowering access to nutrients. This trade-off between permeability and nutritional competence is the source of considerable natural variation in porin gate-keeping. Mutational changes in this trade-off are frequently selected, so susceptibility to detergents and antibiotics is polymorphic in environmental isolates as well as pathogens. Understanding the mechanism, costs and heterogeneity of antibiotic exclusion by porins will be crucial in combating Gram negative infections. PMID:26506392

  17. Selecting robust solutions from a trade-off surface through the evaluation of the distribution of parameter sets in objective space and parameter space

    NASA Astrophysics Data System (ADS)

    Dumedah, G.; Berg, A. A.; Wineberg, M.

    2009-12-01

    Hydrological models are increasingly been calibrated using multi-objective genetic algorithms (GAs). Multi-objective GAs facilitate the evaluation of several model evaluation objectives and the examination of massive combinations of parameter sets. Usually, the outcome is a set of several equally-accurate parameter sets which make-up a trade-off surface between the objective functions often referred to as Pareto set. The Pareto set describes a decision-front in a way that each solution has unique values in parameter space with competing accuracy in objective space. An automated framework of choosing a single from such a trade-off surface has not been thoroughly investigated in the model calibration literature. As a result, this presentation will demonstrate an automated selection of robust solutions from a trade-off surface using the distribution of solutions in both objective space and parameter space. The trade-off surface was generated using the Non-dominated Sorting Genetic Algorithm II (NSGA-II) to calibrate the Soil and Water Assessment Tool (SWAT) for streamflow simulation based on model bias and root mean square error. Our selection method generates solutions with unique properties including a representative pathway in parameter space, a basin of attraction or the center of mass in objective space, and a proximity to the origin in objective space. Additionally, our framework determines a robust solution as a balanced compromise for the distribution of solutions in objective space and parameter space. That is, the robust solution emphasizes stability in model parameter values and in objective function values in a way that similarity in parameter space implies similarity in objective space.

  18. Nutritional physiology of life-history trade-offs: how food protein-carbohydrate content influences life-history traits in the wing-polymorphic cricket Gryllus firmus.

    PubMed

    Clark, Rebecca M; Zera, Anthony J; Behmer, Spencer T

    2015-01-15

    Although life-history trade-offs result from the differential acquisition and allocation of nutritional resources to competing physiological functions, many aspects of this topic remain poorly understood. Wing-polymorphic insects, which possess alternative morphs that trade off allocation to flight capability versus early reproduction, provide a good model system for exploring this topic. In this study, we used the wing-polymorphic cricket Gryllus firmus to test how expression of the flight capability versus reproduction trade-off was modified across a heterogeneous protein-carbohydrate nutritional landscape. Newly molted adult female long- and short-winged crickets were given one of 13 diets with different concentrations and ratios of protein and digestible carbohydrate; for each cricket, we measured consumption patterns, growth and allocation to reproduction (ovary mass) versus flight muscle maintenance (flight muscle mass and somatic lipid stores). Feeding responses in both morphs were influenced more by total macronutrient concentration than by protein-carbohydrate ratio, except at high-macronutrient concentration, where protein-carbohydrate balance was important. Mass gain tended to be greatest on protein-biased diets for both morphs, but was consistently lower across all diets for long-winged females. When long-winged females were fed high-carbohydrate foods, they accumulated greater somatic lipid stores; on high-protein foods, they accumulated greater somatic protein stores. Food protein-carbohydrate content also affected short-winged females (selected for early reproductive onset), which showed dramatic increases in ovary size, including ovarian stores of lipid and protein, on protein-biased foods. This is the first study to show how the concentration and ratio of dietary protein and carbohydrate affects consumption and allocation to key physiological features associated with the reproduction-dispersal life-history trade-off. PMID:25524979

  19. Offspring pay sooner, parents pay later: experimental manipulation of body mass reveals trade-offs between immune function, reproduction and survival

    PubMed Central

    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 in body mass could affect this trade-off: within broods, within season and between years. We handicapped adult skylarks (Alauda arvensis) by attaching extra weight during first broods to both adults of a pair. We measured body mass, immune function and return rates in these birds. We also measured nest success, feeding rates, diet composition, nestling size, nestling immune function and recruitment rates. Results When nestlings of first broods fledged, parent body condition had not changed, but experimental birds experienced higher nest failure. Depending on the year, immune parameters of nestlings from experimental parents were either higher or lower than of control nestlings. Later, when parents were feeding their second brood, the balance between self-maintenance and nest success had shifted. Control and experimental adults differed in immune function, while mass and immune function of their nestlings did not differ. Although weights were removed after breeding, immune measurements during the second brood had the capacity to predict return rates to the next breeding season. Among birds that returned the next year, body condition and reproductive performance a year after the experiment did not differ between treatment groups. Conclusions We conclude that the balance between current reproduction and survival shifts from affecting nestlings to affecting parents as the reproductive season progresses. Furthermore, immune function is apparently one physiological mechanism involved

  20. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient.

    PubMed

    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

  1. Trade-off among different anti-herbivore defence strategies along an altitudinal gradient

    PubMed Central

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

    ERIC Educational Resources Information Center

    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…

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

    ERIC Educational Resources Information Center

    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)

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

    PubMed Central

    Knops, Johannes M. H.; 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 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. PMID:22952692

  5. University Efficiency: Complementariness versus Trade-Off between Teaching, Research and Administrative Activities

    ERIC Educational Resources Information Center

    Sellers-Rubio, Ricardo; Mas-Ruiz, Francisco J.; Casado-Diaz, Ana B.

    2010-01-01

    University managers should be aware of the importance that efficiency has for their own universities, orientating their actions towards research and teaching excellence. This study estimates teaching and research efficiency of the different departments of a university and tests the complementariness versus trade-off between them. The results…

  6. ENGINEERING TRADE-OFFS (ETO) METHODOLOGY DEVELOPMENT (SYSTEMS ANALYSIS BRANCH, SUSTAINABLE TECHNOLOGY DIVISION, NRMRL)

    EPA Science Inventory

    The development of the Engineering Trade-Offs (ETO) methodology is occurring as an in-house effort in 2000. While the conceptual model of ETO has been completed, the practical means of applying the concept requires crafting a reliable tool while testing it in stages to ensure tha...

  7. GARBAGE: A Card Game That Simulates the Trade-Off between Competition and Concern.

    ERIC Educational Resources Information Center

    Thiagarajan, Sivasailam

    1991-01-01

    Describes a simulation card game involved with the dumping of hazardous wastes that was designed to explore the trade-off between industrial competition and social concern. Steps of play are described for the game, which is called GARBAGE, and debriefing techniques are suggested, including an affective phase and a cognitive phase. (LRW)

  8. Regulating Interest when Learning Online: Potential Motivation and Performance Trade-Offs

    ERIC Educational Resources Information Center

    Sansone, Carol; Smith, Jessi L.; Thoman, Dustin B.; MacNamara, Atara

    2012-01-01

    Online learning may be particularly sensitive to self-regulatory trade-offs between maintaining interest and performance. Undergraduates in online or on-campus sections of the same course rated strategies used to motivate studying for the first exam, and interest after the first exam and at semester's end. First exam and final class grades were…

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

    NASA Astrophysics Data System (ADS)

    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.

  10. Parent–offspring conflict and the genetic trade-offs shaping parental investment

    PubMed Central

    Kölliker, Mathias; Boos, Stefan; Wong, Janine W.Y.; Röllin, Lilian; Stucki, Dimitri; Raveh, Shirley; Wu, Min; Meunier, Joël

    2015-01-01

    The genetic conflict between parents and their offspring is a cornerstone of kin selection theory and the gene-centred view of evolution, but whether it actually occurs in natural systems remains an open question. Conflict operates only if parenting is driven by genetic trade-offs between offspring performance and the parent's ability to raise additional offspring, and its expression critically depends on the shape of these trade-offs. Here we investigate the occurrence and nature of genetic conflict in an insect with maternal care, the earwig Forficula auricularia. Specifically, we test for a direct response to experimental selection on female future reproduction and correlated responses in current offspring survival, developmental rate and growth. The results demonstrate genetic trade-offs that differ in shape before and after hatching. Our study not only provides direct evidence for parent–offspring conflict but also highlights that conflict is not inevitable and critically depends on the genetic trade-offs shaping parental investment. PMID:25880586

  11. The Developmental Roots of the Speed-Accuracy Trade-Off

    ERIC Educational Resources Information Center

    Zaal, Frank T. J. M.; Thelen, Esther

    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 improvements in infants' ability to pick up tiny…

  12. Early life disadvantage strengthens flight performance trade-offs in European starlings, Sturnus vulgaris

    PubMed Central

    O'Hagan, Daniel; Andrews, Clare P.; Bedford, Thomas; Bateson, Melissa; Nettle, Daniel

    2015-01-01

    Developmental stress has been shown to affect adult flight performance in birds, with both negative and positive effects reported in the literature. Previous studies have used developmental manipulations that had substantial effects on patterns of growth. They have also examined mean levels of flight performance per individual, rather than investigating how developmental stress might alter trade-offs between different components of flight performance. We recorded multiple components of escape flight performance in 20 adult European starlings previously subjected to a manipulation likely to have altered levels of developmental stress. Siblings had been cross-fostered to nests where they were either slightly larger (advantaged treatment) or slightly smaller (disadvantaged treatment) than their competitors. The manipulation had no detectable effect on growth. However, developmental treatment affected performance in escape flights a year later by strengthening the trade-offs between different flight parameters. Disadvantaged birds faced a steeper trade-off between take-off speed and take-off angle, and a steeper trade-off between take-off angle and total time in flight, than advantaged birds. The results suggest that even subtle early life adversity that has no obvious effect on growth or size can leave a lasting legacy in the form of constraints on locomotor performance later in life. PMID:25843958

  13. ETO - ENGINEERING TRADE-OFFS (SYSTEMS ANALYSIS BRANCH, SUSTAINABLE TECHNOLOGY DIVISION, NRMRL)

    EPA Science Inventory

    The ETO - Engineering Trade-Offs program is to develop a new, integrated decision-making approach to compare/contrast two or more states of being: a benchmark and an alternative, a change in a production process, alternative processes or products. ETO highlights the difference in...

  14. Child Care and Work Absences: Trade-Offs by Type of Care

    ERIC Educational Resources Information Center

    Gordon, Rachel A.; Kaestner, Robert; Korenman, Sanders

    2008-01-01

    Parents face a trade-off in the effect of child-care problems on employment. Whereas large settings may increase problems because of child illness, small group care may relate to provider unavailability. Analyzing the NICHD Study of Early Child Care, we find that child-care centers and large family day care lead to mothers' greater work absences…

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

    ERIC Educational Resources Information Center

    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…

  16. Trade-off between land vehicle antenna cost and gain for satellite mobile communications

    NASA Technical Reports Server (NTRS)

    1984-01-01

    Trade-offs between antenna cost and gain made for nine antennas as a feasibility study for the experimental land mobile satellite system, M-SAT(X) reported. This system is under development by JPL-NASA for a mobile telephone system to be used throughout the continental USA and Alaska. The mobile antenna is a key element in the development of this system.

  17. Site-specific trade-offs of harvesting cereal residues as biofuel feedstocks

    Technology Transfer Automated Retrieval System (TEKTRAN)

    Cereal residues are considered an important feedstock for future biofuel production. Harvesting cereal residues, however, could lead to substantial soil degradation. Our objective was to evaluate trade-offs associated with harvesting straw including impacts on soil erosion and quality, soil organic ...

  18. A Classroom Exercise to Examine the Trade-off between Mission Capacity and Life Cycle Cost

    ERIC Educational Resources Information Center

    Kang, Keebom; Doerr, Kenneth H.

    2015-01-01

    This article presents a classroom exercise, centered on a simulation that has been used for 4 years in an MBA program to help students develop an understanding of the trade-offs involved in managing capital assets in the public sector. Though often ignored in business schools, "mission" is a key criterion that must be considered when…

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

    NASA Astrophysics Data System (ADS)

    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.

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

    ERIC Educational Resources Information Center

    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…

  1. Analysis and trade-off studies of large lightweight mirror structures. [large space telescope

    NASA Technical Reports Server (NTRS)

    Soosaar, K.; Grin, R.; Ayer, F.

    1975-01-01

    A candidate mirror, hexagonally lightweighted, is analyzed under various loadings using as complete a procedure as possible. Successive simplifications are introduced and compared to an original analysis. A model which is a reasonable compromise between accuracy and cost is found and is used for making trade-off studies of the various structural parameters of the lightweighted mirror.

  2. THE LAUNCH WINDOW HYPOTHESIS AND THE SPEED-ACCURACY TRADE-OFF IN BASEBALL THROWING.

    PubMed

    Freeston, Jonathan; Ferdinands, Rene E D; Rooney, Kieron

    2015-08-01

    The speed-accuracy trade-off in throwing has been well described, but its cause is poorly understood. The popular impulse-variability hypothesis lacks relevance to throwing, while the launch window hypothesis has explanatory potential but has not been empirically tested. The current study therefore aimed to quantify the speed-accuracy trade-off and launch window during a throwing task at two different speeds. Nine elite junior baseball players (M age=19.6 yr.; M height=1.80 m; M weight=75.5 kg) threw 10 fastballs at 80 and 100% of maximal throwing speed (MTS) toward a 7 cm target from a distance of 20 m. A 3D motion analysis system measured ball speed and trajectory. A speed-accuracy trade-off occurred, mediated by increased vertical error. This can be attributed to the launch window, which was significantly smaller, particularly its vertical component, during 100% MTS. Maximal throwing speed correlated negatively with launch window size. The launch window hypothesis explained the observed speed-accuracy trade-off, providing a framework within which aspects of technique can be identified and altered to improve performance. PMID:26270853

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

    ERIC Educational Resources Information Center

    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…

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

    PubMed Central

    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 between birth rate and offspring size and a −¼ power scaling between birth rate and body size. We show that these theoretically predicted relationships, in particular the inverse scaling between number and size of offspring, tend to hold across increasingly finer scales of analyses (i.e. from mammals to primates to apes to humans). The advantage of this approach is that the quantity–quality trade-off in humans is placed into a general framework of parental investment that follows directly from first principles of energetic allocation. PMID:18077252

  5. An Education Freedom Index: Why, Key Determinants, Component Weights, and Trade-Offs

    ERIC Educational Resources Information Center

    Merrifield, John

    2011-01-01

    Freedom of any kind has intrinsic value, and education freedom is controversial, in need of empirical assessment of possible and likely trade-offs between freedom from state control and social goals such as equity and cohesion. Without a reasonable empirical measure of education freedom we can only cite the controversies and choose sides. The…

  6. Active rc filter permits easy trade-off of amplifier gain and sensitivity to gain

    NASA Technical Reports Server (NTRS)

    Kerwin, W. J.; Shaffer, C. V.

    1968-01-01

    Passive RC network was designed with zeros of transmission in the right half of the complex frequency plane in the feedback loop of a simple negative-gain amplifier. The proper positioning provides any desired trade-off between amplifier gain and sensitivity to amplifier gain.

  7. Assessing trade-offs between crop production and ecological services: the Calapooia Basin

    Technology Transfer Automated Retrieval System (TEKTRAN)

    In order to assess the trade-offs between crop production and ecological services within a watershed, one must quantify linkages between conservation practices in grass seed producing areas and biophysical responses including water quality and biological indicators and develop a model to assess trad...

  8. Life history trade-offs imposed by dragline use in two money spiders.

    PubMed

    Bonte, Dries; Verduyn, Lieselot; Braeckman, Bart P

    2016-01-01

    Trade-offs among life history traits are central to understanding the limits of adaptations to stress. In animals, virtually all decisions taken during life are expected to have downstream consequences. To what degree rare, but energy-demanding, decisions carry over to individual performance is rarely studied in arthropods. We used spiders as a model system to test how single investments in silk use - for dispersal or predator escape - affect individual performance. Silk produced for safe lines and as threads for ballooning is of the strongest kind and is energetically costly, especially when resources are limited. We induced dragline spinning in two species of money spider at similar quantities to that under natural conditions and tested trade-offs with lifespan and egg sac production under unlimited prey availability and a dietary restriction treatment. We demonstrate strong trade-offs between dragline spinning and survival and fecundity. Survival trade-offs were additive to those imposed by the dietary treatment, but a reduction in eggs produced after silk use was only prevalent under conditions where food was restricted during the spider's life. Because draglines are not recycled after their use for dispersal or predator escape, their spinning incurs substantial fitness costs in dispersal, especially in environments with prey limitation. Rare but energetically costly decisions related to dispersal or predator escape may thus carry over to adult performance and explain phenotypic heterogeneity in natural populations. PMID:26596528

  9. Optimal defense strategies in an idealized microbial food web under trade-off between competition and defense.

    PubMed

    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. PMID:24999739

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

    PubMed Central

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

    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 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. PMID:21789252

  11. Physiological trade-offs in self-maintenance: plumage molt and stress physiology in birds.

    PubMed

    Cornelius, Jamie M; Perfito, Nicole; Zann, Richard; Breuner, Creagh W; Hahn, Thomas P

    2011-08-15

    Trade-offs between self-maintenance processes can affect life-history evolution. Integument replacement and the stress response both promote self-maintenance and affect survival in vertebrates. Relationships between the two processes have been studied most extensively in birds, where hormonal stress suppression is down regulated during molt in seasonal species, suggesting a resource-based trade-off between the two processes. The only species found to differ are the rock dove and Eurasian tree sparrow, at least one of which performs a very slow molt that may reduce resource demands during feather growth, permitting investment in the stress response. To test for the presence of a molt-stress response trade-off, we measured hormonal stress responsiveness during and outside molt in two additional species with extended molts, red crossbills (Loxia curvirostra) and zebra finches (Taeniopygia guttata). We found that both species maintain hormonal stress responsiveness during molt. Further, a comparative analysis of all available species revealed a strong relationship between molt duration and degree of hormonal suppression. Though our results support trade-off hypotheses, these data can also be explained by alternative hypotheses that have not been formally addressed in the literature. We found a strong relationship between stress suppression and seasonality of breeding and evidence suggesting that the degree of suppression may be either locally adaptable or plastic and responsive to local environmental conditions. We hypothesize that environmental unpredictability favors extended molt duration, which in turn allows for maintenance of the hormonal stress response, and discuss implications of a possible trade-off for the evolution of molt schedules. PMID:21795575

  12. Trade-off decisions in distribution utility management

    NASA Astrophysics Data System (ADS)

    Slavickas, Rimas Anthony

    As a result of the "unbundling" of traditional monopolistic electricity generation and transmission enterprises into a free-market economy, power distribution utilities are faced with very difficult decisions pertaining to electricity supply options and quality of service to the customers. The management of distribution utilities has become increasingly complex, versatile, and dynamic to the extent that conventional, non-automated management tools are almost useless and obsolete. This thesis presents a novel and unified approach to managing electricity supply options and quality of service to customers. The technique formulates the problem in terms of variables, parameters, and constraints. An advanced Mixed Integer Programming (MIP) optimization formulation is developed together with novel, logical, decision-making algorithms. These tools enable the utility management to optimize various cost components and assess their time-trend impacts, taking into account the intangible issues such as customer perception, customer expectation, social pressures, and public response to service deterioration. The above concepts are further generalized and a Logical Proportion Analysis (LPA) methodology and associated software have been developed. Solutions using numbers are replaced with solutions using words (character strings) which more closely emulate the human decision-making process and advance the art of decision-making in the power utility environment. Using practical distribution utility operation data and customer surveys, the developments outlined in this thesis are successfully applied to several important utility management problems. These involve the evaluation of alternative electricity supply options, the impact of rate structures on utility business, and the decision of whether to continue to purchase from a main grid or generate locally (partially or totally) by building Non-Utility Generation (NUG).

  13. Give 'til it hurts: trade-offs between immunity and male reproductive effort in the decorated cricket, Gryllodes sigillatus.

    PubMed

    Gershman, S N; Barnett, C A; Pettinger, A M; Weddle, C B; Hunt, J; Sakaluk, S K

    2010-04-01

    Trade-offs between life-history variables can be manifested at either the phenotypic or genetic level, with vastly different evolutionary consequences. Here, we examined whether male decorated crickets (Gryllodes sigillatus) from eight inbred lines and the outbred founder population from which they were derived, trade-off immune effort [lytic activity, phenoloxidase (PO) activity or encapsulation] to produce spermatophylaxes: costly nuptial food gifts essential for successful sperm transfer. Canonical correlation analysis of the outbred population revealed a trade-off between spermatophylax mass and lytic activity. Analysis of our inbred lines, however, revealed that although PO activity, encapsulation, body mass, spermatophylax mass and ampulla (sperm capsule) mass were all highly heritable, lytic activity was not, and there was, therefore, no negative genetic correlation between lytic activity and spermatophylax mass. Thus, males showed a phenotypic but not a genetic trade-off between spermatophylax mass and lytic activity, suggesting that this trade-off is mediated largely by environmental factors. PMID:20210833

  14. Analytical study of pressure balancing in gas film seals.

    NASA Technical Reports Server (NTRS)

    Zuk, J.

    1973-01-01

    Proper pressure balancing of gas film seals requires knowledge of the pressure profile load factor (load factor) values for a given set of design conditions. In this study, the load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however, the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.

  15. Multidimensional trade-offs in species responses to disturbance: implications for diversity in a subtropical forest.

    PubMed

    Uriarte, María; Clark, James S; Zimmerman, Jess K; Comita, Liza S; Forero-Montaña, Jimena; Thompson, Jill

    2012-01-01

    Species employ diverse strategies to cope with natural disturbance, but the importance of these strategies for maintaining tree species diversity in forests has been debated. Mechanisms that have the potential to promote tree species coexistence in the context of repeated disturbance include life history trade-offs in colonization and competitive ability or in species' ability to survive at low resource conditions and exploit the temporary resource-rich conditions often generated in the wake of disturbance (successional niche). Quantifying these trade-offs requires long-term forest monitoring and modeling. We developed a hierarchical Bayes model to investigate the strategies tree species employ to withstand and recover from hurricane disturbance and the life history trade-offs that may facilitate species coexistence in forests subject to repeated hurricane disturbance. Unlike previous approaches, our model accommodates temporal variation in process error and observations from multiple sources. We parameterized the model using growth and mortality data from four censuses of a 16-ha plot taken every five years (1990-2005), together with damage data collected after two hurricanes and annual seed production data (1992-2005). Species' susceptibilities to hurricane damage as reflected by changes in diameter growth and fecundity immediately following a storm were weak, highly variable, and unpredictable using traditional life history groupings. The lower crowding conditions (e.g., high light) generated in the wake of storms, however, led to greater gains in growth and fecundity for pioneer and secondary-forest species than for shade-tolerant species, in accordance with expectation of life history. We found moderate trade-offs between survival in high crowding conditions, a metric of competitive ability, and long-distance colonization. We also uncovered a strong trade-off between mean species fecundity in low crowding conditions, a metric of recovery potential, and

  16. Pressure Balanced, Low Hysteresis Finger Seal Test Results

    NASA Technical Reports Server (NTRS)

    Arora, Gul K.; Proctor, Margaret; Steinetz, Bruce M.; Delgado, Irebert R.

    2000-01-01

    The purpose of this presentation is to demonstrate: low cost photoetching fabrication technique; pressure balanced finger seal design; and finger seal operation. The tests and analyses includes: finger seal air leakage analysis; rotor-run out and endurance tests; and extensive analytical work and rig testing.

  17. Assessment of plantar pressure and balance in patients with diabetes

    PubMed Central

    Anjos, Daniela M.C.; Gomes, Luciana P.O.; Sampaio, Luciana M.M.; Correa, João C.F.

    2010-01-01

    Introduction Patients with diabetes for more than 10 years may have an increase in peak plantar pressure, considerable postural oscillation, balance deficit, alterations in gait pattern and an increased risk of falls. The aim of the present study was to assess the correlation between plantar pressure distribution and balance in patients with diabetes using a pressure platform (Footwork). Material and methods The study was carried out at the Human Movement Clinic of the Centro Universitário de Belo Horizonte (Brazil). The sample was made up of 18 right-handed individuals with type 2 diabetes – 14 females and 4 males – with an average age of 58.72 ±9.54 and an average of 18.56 ±6.61 years since diagnosis. Result Data analysis revealed that greater peak plantar pressure on the right hindfoot led to greater radial displacement (Rd) (r = 0.2022) and greater displacement velocity (r = 0.2240). Greater peak plantar pressure on the left hindfoot also led to greater displacement velocity (P) (r = 0.5728) and radial displacement (RD) (r = 0.1972). A positive correlation was found between time elapsed since diagnosis and peak midfoot pressure (r = 0.3752) on the right and left side as well as between BMI and plantar pressure on all regions of the foot. Conclusions The data reveal a correlation between postural oscillation and peak plantar pressure on the hindfoot. PMID:22371719

  18. Trade-offs between fuel economy and NOx emissions using fuzzy logic control.

    SciTech Connect

    Rousseau, Aymeric; Saglini, Sylvain; Jakov, Michael; Gray, Donald; Hardy, Keith

    2002-08-19

    The Center for Transportation Research at the Argonne National Laboratory (ANL) supports the DOE by evaluating advanced automotive technologies in a systems context. ANL has developed a unique set of compatible simulation tools and test equipment to perform an integrated systems analysis project from modeling through hardware testing and validation. This project utilized these capabilities to demonstrate the trade-off in fuel economy and Oxides of Nitrogen (NOx) emissions in a so-called ''pre-transmission'' parallel hybrid powertrain. The powertrain configuration (in simulation and on the dynamometer) consists of a Compression Ignition Direct Ignition (CIDI) engine, a Continuously Variable Transmission (CVT) and an electric drive motor coupled to the CVT input shaft. The trade-off is studied in a simulated environment using PSAT{copyright} with different controllers (fuzzy logic and rule based) and engine models (neural network and steady state models developed from ANL data).

  19. State-independent error-disturbance trade-off for measurement operators

    NASA Astrophysics Data System (ADS)

    Zhou, S. S.; Wu, Shengjun; Chau, H. F.

    2016-05-01

    In general, classical measurement statistics of a quantum measurement is disturbed by performing an additional incompatible quantum measurement beforehand. Using this observation, we introduce a state-independent definition of disturbance by relating it to the distinguishability problem between two classical statistical distributions - one resulting from a single quantum measurement and the other from a succession of two quantum measurements. Interestingly, we find an error-disturbance trade-off relation for any measurements in two-dimensional Hilbert space and for measurements with mutually unbiased bases in any finite-dimensional Hilbert space. This relation shows that error should be reduced to zero in order to minimize the sum of error and disturbance. We conjecture that a similar trade-off relation with a slightly relaxed definition of error can be generalized to any measurements in an arbitrary finite-dimensional Hilbert space.

  20. Sexual fidelity trade-offs promote regulatory variation in the prairie vole brain.

    PubMed

    Okhovat, Mariam; Berrio, Alejandro; Wallace, Gerard; Ophir, Alexander G; Phelps, Steven M

    2015-12-11

    Individual variation in social behavior seems ubiquitous, but we know little about how it relates to brain diversity. Among monogamous prairie voles, levels of vasopressin receptor (encoded by the gene avpr1a) in brain regions related to spatial memory predict male space use and sexual fidelity in the field. We find that trade-offs between the benefits of male fidelity and infidelity are reflected in patterns of territorial intrusion, offspring paternity, avpr1a expression, and the evolutionary fitness of alternative avpr1a alleles. DNA variation at the avpr1a locus includes polymorphisms that reliably predict the epigenetic status and neural expression of avpr1a, and patterns of DNA diversity demonstrate that avpr1a regulatory variation has been favored by selection. In prairie voles, trade-offs in the fitness consequences of social behaviors seem to promote neuronal and molecular diversity. PMID:26659055

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

    NASA Astrophysics Data System (ADS)

    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.

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

    PubMed

    Qin, Keyu; Li, Jing; Yang, Xiaonan

    2015-11-01

    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. PMID:26540068

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

    PubMed Central

    Qin, Keyu; Li, Jing; Yang, Xiaonan

    2015-01-01

    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. PMID:26540068

  4. Risk sensitivity in a motor task with speed-accuracy trade-off

    PubMed Central

    Braun, Daniel A.; Wolpert, Daniel M.

    2011-01-01

    When a racing driver steers a car around a sharp bend, there is a trade-off between speed and accuracy, in that high speed can lead to a skid whereas a low speed increases lap time, both of which can adversely affect the driver's payoff function. While speed-accuracy trade-offs have been studied extensively, their susceptibility to risk sensitivity is much less understood, since most theories of motor control are risk neutral with respect to payoff, i.e., they only consider mean payoffs and ignore payoff variability. Here we investigate how individual risk attitudes impact a motor task that involves such a speed-accuracy trade-off. We designed an experiment where a target had to be hit and the reward (given in points) increased as a function of both subjects' endpoint accuracy and endpoint velocity. As faster movements lead to poorer endpoint accuracy, the variance of the reward increased for higher velocities. We tested subjects on two reward conditions that had the same mean reward but differed in the variance of the reward. A risk-neutral account predicts that subjects should only maximize the mean reward and hence perform identically in the two conditions. In contrast, we found that some (risk-averse) subjects chose to move with lower velocities and other (risk-seeking) subjects with higher velocities in the condition with higher reward variance (risk). This behavior is suboptimal with regard to maximizing the mean number of points but is in accordance with a risk-sensitive account of movement selection. Our study suggests that individual risk sensitivity is an important factor in motor tasks with speed-accuracy trade-offs. PMID:21430284

  5. Mate choice trade-offs and women's preference for physically attractive men.

    PubMed

    Waynforth, D

    2001-09-01

    Researchers studying human sexuality have repeatedly concluded that men place more emphasis on the physical attractiveness of potential mates than women do, particularly in long-term sexual relationships. Evolutionary theorists have suggested that this is the case because male mate value (the total value of the characteristics that an individual possesses in terms of the potential contribution to his or her mate's reproductive success) is better predicted by social status and economic resources, whereas women's mate value hinges on signals conveyed by their physical appearance. This pattern may imply that women trade off attractiveness for resources in mate choice. Here I test whether a trade-off between resources and attractiveness seems to be occurring in the mate choice decisions of women in the United States. In addition, the possibility that the risk of mate desertion drives women to choose less attractive men as long-term mates is tested. The results were that women rated physically attractive men as more likely to cheat or desert a long-term relationship, whereas men did not consider attractive women to be more likely to cheat. However, women showed no aversion to the idea of forming long-term relationships with attractive men. Evidence for a trade-off between resources and attractiveness was found for women, who traded off attractiveness, but not other traits, for resources. The potential meaning of these findings, as well as how they relate to broader issues in the study of sex differences in the evolution of human mate choice for physical traits, is discussed. PMID:26192277

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

    SciTech Connect

    Duan Runyao; Feng Yuan; Li Xin; Ying Mingsheng

    2005-06-15

    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.

  7. Risk sensitivity in a motor task with speed-accuracy trade-off.

    PubMed

    Nagengast, Arne J; Braun, Daniel A; Wolpert, Daniel M

    2011-06-01

    When a racing driver steers a car around a sharp bend, there is a trade-off between speed and accuracy, in that high speed can lead to a skid whereas a low speed increases lap time, both of which can adversely affect the driver's payoff function. While speed-accuracy trade-offs have been studied extensively, their susceptibility to risk sensitivity is much less understood, since most theories of motor control are risk neutral with respect to payoff, i.e., they only consider mean payoffs and ignore payoff variability. Here we investigate how individual risk attitudes impact a motor task that involves such a speed-accuracy trade-off. We designed an experiment where a target had to be hit and the reward (given in points) increased as a function of both subjects' endpoint accuracy and endpoint velocity. As faster movements lead to poorer endpoint accuracy, the variance of the reward increased for higher velocities. We tested subjects on two reward conditions that had the same mean reward but differed in the variance of the reward. A risk-neutral account predicts that subjects should only maximize the mean reward and hence perform identically in the two conditions. In contrast, we found that some (risk-averse) subjects chose to move with lower velocities and other (risk-seeking) subjects with higher velocities in the condition with higher reward variance (risk). This behavior is suboptimal with regard to maximizing the mean number of points but is in accordance with a risk-sensitive account of movement selection. Our study suggests that individual risk sensitivity is an important factor in motor tasks with speed-accuracy trade-offs. PMID:21430284

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

    PubMed

    Saino, Nicola; Romano, Maria; Rubolini, Diego; Ambrosini, Roberto; Romano, Andrea; Caprioli, Manuela; Costanzo, Alessandra; Bazzi, Gaia

    2014-01-01

    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. PMID:24826890

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

    NASA Technical Reports Server (NTRS)

    Williams, Brent A.

    2011-01-01

    This paper approaches the noise versus resolution trade-off in wind scatterometry from a field-wise retrieval perspective. Theoretical considerations are discussed and practical implementation using a MAP estimator is applied to the Sea-Winds scatterometer. The approach is compared to conventional approaches as well as numerical weather predictions. The new approach incorporates knowledge of the wind spectrum to reduce the impact of components of the wind signal that are expected to be noisy.

  10. Muscle trade-offs in a power-amplified prey capture system.

    PubMed

    Blanco, M Mendoza; Patek, S N

    2014-05-01

    Should animals operating at great speeds and accelerations use fast or slow muscles? The answer hinges on a fundamental trade-off: muscles can be maximally fast or forceful, but not both. Direct lever systems offer a straightforward manifestation of this trade-off, yet the fastest organisms use power amplification, not direct lever action. Power-amplified systems typically use slow, forceful muscles to preload springs, which then rapidly release elastic potential energy to generate high speeds and accelerations. However, a fast response to a stimulus may necessitate fast spring-loading. Across 22 mantis shrimp species (Stomatopoda), this study examined how muscle anatomy correlates with spring mechanics and appendage type. We found that muscle force is maximized through physiological cross-sectional area, but not through sarcomere length. Sit-and-wait predators (spearers) had the shortest sarcomere lengths (fastest contractions) and the slowest strike speeds. The species that crush shells (smashers) had the fastest speeds, most forceful springs, and longest sarcomeres. The origin of the smasher clade yielded dazzlingly high accelerations, perhaps due to the release from fast spring-loading for evasive prey capture. This study offers a new window into the dynamics of force-speed trade-offs in muscles in the biomechanical, comparative evolutionary framework of power-amplified systems. PMID:24475749

  11. Evading the strength–ductility trade-off dilemma in steel through gradient hierarchical nanotwins

    PubMed Central

    Wei, Yujie; Li, Yongqiang; Zhu, Lianchun; Liu, Yao; Lei, Xianqi; Wang, Gang; Wu, Yanxin; Mi, Zhenli; Liu, Jiabin; Wang, Hongtao; Gao, Huajian

    2014-01-01

    The strength–ductility trade-off has been a long-standing dilemma in materials science. This has limited the potential of many structural materials, steels in particular. Here we report a way of enhancing the strength of twinning-induced plasticity steel at no ductility trade-off. After applying torsion to cylindrical twinning-induced plasticity steel samples to generate a gradient nanotwinned structure along the radial direction, we find that the yielding strength of the material can be doubled at no reduction in ductility. It is shown that this evasion of strength–ductility trade-off is due to the formation of a gradient hierarchical nanotwinned structure during pre-torsion and subsequent tensile deformation. A series of finite element simulations based on crystal plasticity are performed to understand why the gradient twin structure can cause strengthening and ductility retention, and how sequential torsion and tension lead to the observed hierarchical nanotwinned structure through activation of different twinning systems. PMID:24686581

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

    PubMed

    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

  13. Shifting Fitness and Epistatic Landscapes Reflect Trade-offs along an Evolutionary Pathway.

    PubMed

    Steinberg, Barrett; Ostermeier, Marc

    2016-07-01

    Nature repurposes proteins via evolutionary processes. Such adaptation can come at the expense of the original protein's function, which is a trade-off of adaptation. We sought to examine other potential adaptive trade-offs. We measured the effect on ampicillin resistance of ~12,500 unique single amino acid mutants of the TEM-1, TEM-17, TEM-19, and TEM-15 β-lactamase alleles, which constitute an adaptive path in the evolution of cefotaxime resistance. These protein fitness landscapes were compared and used to calculate epistatic interactions between these mutations and the two mutations in the pathway (E104K and G238S). This series of protein fitness landscapes provides a systematic, quantitative description of pairwise/tertiary intragenic epistasis involving adaptive mutations. We find that the frequency of mutations exhibiting epistasis increases along the evolutionary pathway. Adaptation moves the protein to a region in the fitness landscape characterized by decreased mutational robustness and increased ruggedness, as measured by fitness effects of mutations and epistatic interactions for TEM-1's original function. This movement to such a "fitness territory" has evolutionary consequences and is an important adaptive trade-off and cost of adaptation. Our systematic study provides detailed insight into the relationships between mutation, protein structure, protein stability, and epistasis and quantitatively depicts the different costs inherent in the evolution of new functions. PMID:27173379

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

    NASA Astrophysics Data System (ADS)

    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.

  15. Early-late life trade-offs and the evolution of ageing in the wild

    PubMed Central

    Lemaître, Jean-François; Berger, Vérane; Bonenfant, Christophe; Douhard, Mathieu; Gamelon, Marlène; Plard, Floriane; Gaillard, Jean-Michel

    2015-01-01

    Empirical evidence for declines in fitness components (survival and reproductive performance) with age has recently accumulated in wild populations, highlighting that the process of senescence is nearly ubiquitous in the living world. Senescence patterns are highly variable among species and current evolutionary theories of ageing propose that such variation can be accounted for by differences in allocation to growth and reproduction during early life. Here, we compiled 26 studies of free-ranging vertebrate populations that explicitly tested for a trade-off between performance in early and late life. Our review brings overall support for the presence of early-late life trade-offs, suggesting that the limitation of available resources leads individuals to trade somatic maintenance later in life for high allocation to reproduction early in life. We discuss our results in the light of two closely related theories of ageing—the disposable soma and the antagonistic pleiotropy theories—and propose that the principle of energy allocation roots the ageing process in the evolution of life-history strategies. Finally, we outline research topics that should be investigated in future studies, including the importance of natal environmental conditions in the study of trade-offs between early- and late-life performance and the evolution of sex-differences in ageing patterns. PMID:25833848

  16. Trade-offs between immune investment and sexual signaling in male mallards.

    PubMed

    Peters, Anne; Delhey, Kaspar; Denk, Angelika G; Kempenaers, Bart

    2004-07-01

    Allocation trade-offs between the immune system and sexual traits are central to current sexual selection hypotheses but remain contentious. Such trade-offs could be brought about by the dual action of testosterone that stimulates sexual signals but also suppresses immune functions and/or by competition for carotenoids that can be deposited in ornaments or used as antioxidants in support of immune functions. We investigated the trade-off between investment in immunity and maintenance of testosterone, carotenoids, and sexually selected, carotenoid-based bill color in male mallards. Following a nonpathogenic immune challenge, facultative immune investment resulted in a syndrome of changes in allocation. Plasma carotenoids disappeared from circulation proportional to antibody production. In addition, the reflectance spectrum of the bill was affected; greater antibody production was associated with an increase in relative UV reflectance. Although changes in bill reflectance and plasma carotenoids were related, the relationship appeared more complex than direct competition with immunity. Finally, maintenance of testosterone was affected by immune investment: testosterone levels declined substantially when males produced more antibodies. Because males with high testosterone are preferred by females, the decline in testosterone, in addition to carotenoid depletion and effects on bill reflectance, could constitute a significant cost of immune investment. PMID:15266370

  17. No Trade-Off between Growth Rate and Temperature Stress Resistance in Four Insect Species

    PubMed Central

    Karl, Isabell; Stoks, Robby; Bauerfeind, Stephanie S.; Dierks, Anneke; Franke, Kristin; Fischer, Klaus

    2013-01-01

    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. PMID:23638084

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

    PubMed Central

    Johnston, S.L; Grune, T; Bell, L.M; Murray, S.J; 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’ theories by examining the fecundities of C57BL/6J mice placed onto four different dietary treatments that generated caloric intakes from −21 to +8.6% of controls. We predicted body fat would be deposited in relation to caloric intake. Excessive body fat is known to cause co-morbidities that shorten lifespan, while caloric restriction enhances somatic protection and increases longevity. The trade-off model predicts that increased fat would be tolerated because reproductive gain offsets shortened longevity, while animals on a restricted intake would sacrifice reproduction for lifespan extension. The responses of body fat to treatments followed our expectations, however, there was a negative relationship between reproductive performance (fecundity, litter mass) and historical intake/body fat. Our dietary restricted animals had lower protein oxidative damage and appeared able to combine life-history traits in a manner contrary to traditional expectations by having increased fecundity with the potential to have extended lifespans. PMID:16777725

  19. Assessing trade-offs to inform ecosystem-based fisheries management of forage fish

    PubMed Central

    Shelton, Andrew Olaf; Samhouri, Jameal F.; Stier, Adrian C.; Levin, Philip S.

    2014-01-01

    Twenty-first century conservation is centered on negotiating trade-offs between the diverse needs of people and the needs of the other species constituting coupled human-natural ecosystems. Marine forage fishes, such as sardines, anchovies, and herring, are a nexus for such trade-offs because they are both central nodes in marine food webs and targeted by fisheries. An important example is Pacific herring, Clupea pallisii in the Northeast Pacific. Herring populations are subject to two distinct fisheries: one that harvests adults and one that harvests spawned eggs. We develop stochastic, age-structured models to assess the interaction between fisheries, herring populations, and the persistence of predators reliant on herring populations. We show that egg- and adult-fishing have asymmetric effects on herring population dynamics - herring stocks can withstand higher levels of egg harvest before becoming depleted. Second, ecosystem thresholds proposed to ensure the persistence of herring predators do not necessarily pose more stringent constraints on fisheries than conventional, fishery driven harvest guidelines. Our approach provides a general template to evaluate ecosystem trade-offs between stage-specific harvest practices in relation to environmental variability, the risk of fishery closures, and the risk of exceeding ecosystem thresholds intended to ensure conservation goals are met. PMID:25407879

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

    PubMed Central

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

  1. Trade-off between male and female allocation in the simultaneously hermaphroditic flatworm Macrostomum sp.

    PubMed

    Schärer, L; Sandner, P; Michiels, N K

    2005-03-01

    Sex allocation theory for simultaneous hermaphrodites assumes a direct trade-off between the allocation of resources to the male and female reproductive functions. Empirical support for this basic assumption is scarce, possibly because studies rarely control for variation in individual reproductive resource budgets. Such variation, which can have environmental or genetic sources, can generate a positive relationship between male and female investment and can thus obscure the trade-off. In this study on the hermaphroditic flatworm Macrostomum sp. we tried to control for budget effects by restricting food availability in a standardized way and by using an inbred line. We then manipulated mating group size in a two-way design (two group sizes x two enclosure sizes) in order to induce phenotypic variation in male allocation, and expected to find an opposing correlated response in female allocation. The results suggest that we only managed to control the budget effects under some conditions. Under these the sex allocation trade-off emerged. Under the other conditions we found a strongly positive correlation between male and female allocation. We discuss possible causes for the observed differences. PMID:15715845

  2. Early-late life trade-offs and the evolution of ageing in the wild.

    PubMed

    Lemaître, Jean-François; Berger, Vérane; Bonenfant, Christophe; Douhard, Mathieu; Gamelon, Marlène; Plard, Floriane; Gaillard, Jean-Michel

    2015-05-01

    Empirical evidence for declines in fitness components (survival and reproductive performance) with age has recently accumulated in wild populations, highlighting that the process of senescence is nearly ubiquitous in the living world. Senescence patterns are highly variable among species and current evolutionary theories of ageing propose that such variation can be accounted for by differences in allocation to growth and reproduction during early life. Here, we compiled 26 studies of free-ranging vertebrate populations that explicitly tested for a trade-off between performance in early and late life. Our review brings overall support for the presence of early-late life trade-offs, suggesting that the limitation of available resources leads individuals to trade somatic maintenance later in life for high allocation to reproduction early in life. We discuss our results in the light of two closely related theories of ageing-the disposable soma and the antagonistic pleiotropy theories-and propose that the principle of energy allocation roots the ageing process in the evolution of life-history strategies. Finally, we outline research topics that should be investigated in future studies, including the importance of natal environmental conditions in the study of trade-offs between early- and late-life performance and the evolution of sex-differences in ageing patterns. PMID:25833848

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

    NASA Astrophysics Data System (ADS)

    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.

  4. Plasma etch patterning of EUV lithography: balancing roughness and selectivity trade off

    NASA Astrophysics Data System (ADS)

    Rastogi, Vinayak; Beique, Genevieve; Sun, Lei; Cottle, Hongyun; Feurprier, Yannick; Metz, Andrew; Kumar, Kaushik; Labelle, Cathy; Arnold, John; Colburn, Matthew; Ranjan, Alok

    2016-03-01

    EUV based patterning is one of the frontrunner candidates enabling scaling for future technology nodes. However it poses the common challenges of `pattern roughness' and `etch resistance' aspect which are getting even more critical as we work on smaller dimension features. Continuous efforts are ongoing to improve resist materials and lithography process but the industry is slowly moving to introduce it at high volume manufacturing. Plasma Etch processes have the potential to improvise upon the incoming pattern roughness and provide improved LER/LWR downstream to expedite EUV progress. In this work we demonstrate the specific role of passivation control in the dualfrequency Capacitively Coupled Plasma (CCP) for EUV patterning process with regards to improving LER/LWR, resist selectivity and CD tunability for line/space patterns. We draw the implicit commonalities between different passivation chemistry and their effectiveness for roughness improvement. The effect of relative C:F and C:H ratio in feed gas on CFx and CHx plasma species and in turn the evolution of pattern roughness is drawn. Data that shows the role of plasma etch parameters impacting the key patterning metrics of CD, resist selectivity and LER/LWR is presented.

  5. Analytical study of pressure balancing in gas film seals

    NASA Technical Reports Server (NTRS)

    Zuk, J.

    1973-01-01

    The load factor is investigated for subsonic and choked flow conditions, laminar and turbulent flows, and various seal entrance conditions. Both parallel sealing surfaces and surfaces with small linear deformation were investigated. The load factor for subsonic flow depends strongly on pressure ratio; under choked flow conditions, however the load factor is found to depend more strongly on film thickness and flow entrance conditions rather than pressure ratio. The importance of generating hydrodynamic forces to keep the seal balanced under severe and multipoint operation is also discussed.

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

    USGS Publications Warehouse

    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.

  7. Fitness trade-offs in pest management and intercropping with colour: an evolutionary framework and potential application

    PubMed Central

    Farkas, Timothy E

    2015-01-01

    An important modern goal of plant science research is to develop tools for agriculturalists effective at curbing yield losses to insect herbivores, but resistance evolution continuously threatens the efficacy of pest management strategies. The high-dose/refuge strategy has been employed with some success to curb pest adaptation, and has been shown to be most effective when fitness costs (fitness trade-offs) of resistance are high. Here, I use eco-evolutionary reasoning to demonstrate the general importance of fitness trade-offs for pest control, showing that strong fitness trade-offs mitigate the threat of pest adaptation, even if adaptation were to occur. I argue that novel pest management strategies evoking strong fitness trade-offs are the most likely to persist in the face of unbridled pest adaptation, and offer the manipulation of crop colours as a worked example of one potentially effective strategy against insect herbivores. PMID:26495038

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

    EPA Science Inventory

    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...

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

    PubMed

    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

  10. Grayscale/resolution trade-off for text: Model predictions and psychophysical results for letter confusion and letter discrimination

    NASA Technical Reports Server (NTRS)

    Gille, Jennifer; Martin, Russel; Lubin, Jeffrey; Larimer, James

    1995-01-01

    In a series of papers presented in 1994, we examined the grayscale/resolution trade-off for natural images displayed on devices with discrete pixellation, such as AMLCD's. In the present paper we extend this study by examining the grayscale/resolution trade-off for text images on discrete-pixel displays. Halftoning in printing is an example of the grayscale/resolution trade-off. In printing, spatial resolution is sacrificed to produce grayscale. Another example of this trade-off is the inherent low-pass spatial filter of a CRT, caused by the point-spread function of the electron beam in the phosphor layer. On a CRT, sharp image edges are blurred by this inherent low-pass filtering, and the block noise created by spatial quantization is greatly reduced. A third example of this trade-off is text anti-aliasing, where grayscale is used to improve letter shape, size and location when rendered at a low spatial resolution. There are additional implications for display system design from the grayscale/resolution trade-off. For example, reduced grayscale can reduce system costs by requiring less complexity in the framestore, allowing the use of lower cost drivers, potentially increasing data transfer rates in the image subsystem, and simplifying the manufacturing processes that are used to construct the active matrix for AMLCD (active-matrix liquid-crystal display) or AMTFEL (active-matrix thin-film electroluminescent) devices. Therefore, the study of these trade-offs is important for display designers and manufacturing and systems engineers who wish to create the highest performance, lowest cost device possible. Our strategy for investigating this trade-off is to generate a set of simple test images, manipulate grayscale and resolution, predict discrimination performance using the ViDEOS(Sarnoff) Human Vision Model, conduct an empirical study of discrimination using psychophysical procedures, and verify the computational results using the psychophysical results.

  11. Are Trade-Offs Among Species’ Ecological Interactions Scale Dependent? A Test Using Pitcher-Plant Inquiline Species

    PubMed Central

    Kneitel, Jamie M.

    2012-01-01

    Trade-offs among species’ ecological interactions is a pervasive explanation for species coexistence. The traits associated with trade-offs are typically measured to mechanistically explain species coexistence at a single spatial scale. However, species potentially interact at multiple scales and this may be reflected in the traits among coexisting species. I quantified species’ ecological traits associated with the trade-offs expected at both local (competitive ability and predator tolerance) and regional (competitive ability and colonization rate) community scales. The most common species (four protozoa and a rotifer) from the middle trophic level of a pitcher plant (Sarracenia purpurea) inquiline community were used to link species traits to previously observed patterns of species diversity and abundance. Traits associated with trade-offs (competitive ability, predator tolerance, and colonization rate) and other ecological traits (size, growth rate, and carrying capacity) were measured for each of the focal species. Traits were correlated with one another with a negative relationship indicative of a trade-off. Protozoan and rotifer species exhibited a negative relationship between competitive ability and predator tolerance, indicative of coexistence at the local community scale. There was no relationship between competitive ability and colonization rate. Size, growth rate, and carrying capacity were correlated with each other and the trade-off traits: Size was related to both competitive ability and predator tolerance, but growth rate and carrying capacity were correlated with predator tolerance. When partial correlations were conducted controlling for size, growth rate and carrying capacity, the trade-offs largely disappeared. These results imply that body size is the trait that provides the basis for ecological interactions and trade-offs. Altogether, this study showed that the examination of species’ traits in the context of coexistence at different

  12. Are trade-offs among species' ecological interactions scale dependent? A test using pitcher-plant inquiline species.

    PubMed

    Kneitel, Jamie M

    2012-01-01

    Trade-offs among species' ecological interactions is a pervasive explanation for species coexistence. The traits associated with trade-offs are typically measured to mechanistically explain species coexistence at a single spatial scale. However, species potentially interact at multiple scales and this may be reflected in the traits among coexisting species. I quantified species' ecological traits associated with the trade-offs expected at both local (competitive ability and predator tolerance) and regional (competitive ability and colonization rate) community scales. The most common species (four protozoa and a rotifer) from the middle trophic level of a pitcher plant (Sarracenia purpurea) inquiline community were used to link species traits to previously observed patterns of species diversity and abundance. Traits associated with trade-offs (competitive ability, predator tolerance, and colonization rate) and other ecological traits (size, growth rate, and carrying capacity) were measured for each of the focal species. Traits were correlated with one another with a negative relationship indicative of a trade-off. Protozoan and rotifer species exhibited a negative relationship between competitive ability and predator tolerance, indicative of coexistence at the local community scale. There was no relationship between competitive ability and colonization rate. Size, growth rate, and carrying capacity were correlated with each other and the trade-off traits: Size was related to both competitive ability and predator tolerance, but growth rate and carrying capacity were correlated with predator tolerance. When partial correlations were conducted controlling for size, growth rate and carrying capacity, the trade-offs largely disappeared. These results imply that body size is the trait that provides the basis for ecological interactions and trade-offs. Altogether, this study showed that the examination of species' traits in the context of coexistence at different scales

  13. Trade-offs between nitrous oxide emission and C-sequestration in the soil: the role of earthworms

    NASA Astrophysics Data System (ADS)

    van Groenigen, J.; Lubbers, I. M.; Giannopoulos, G.

    2008-12-01

    The rapidly rising concentrations of the greenhouse gas carbon dioxide (CO2) in the atmosphere has spurred the interest in soils as a potential carbon (C) sink. However, there are many reports indicating that C- sequestration is often negated by elevated emissions of the potent greenhouse gas nitrous oxide (N2O). It is not yet clear what the driving factors behind this trade-off are, nor how it can be avoided. We suggest that earthworm activity may be partly responsible for the trade-off. Earthworm activity is increasingly recognized as being beneficial to C-sequestration through stabilization of SOM. We report experimental results suggesting that they can also lead to strongly elevated N2O-emissions. In a first experiment, dried grass residue (Lolium perenne) was applied at the top of a loamy soil or mixed through the soil, and N2O-emission was followed for three months. Treatments included presence of the epigeic earthworm Lumbricus rubellus and the anecic earthworm Aporrectodea longa. Cumulative N2O-emissions increased significantly for both species. The strongest effect was measured for L. rubellus, where N2O-emissions significantly increased from 55.7 to 789.1 micro g N2O-N kg- 1 soil. This effect was only observed when residue was applied on top of the soil. In a second experiment we determined the effect of epigeic (L. rubellus) and endogeic (Aporrectodea caliginosa) earthworms on N2O-emissions for two different soil types (loam and sand) in the presence of 15N-labeled radish residue (Raphanus sativus subsp. oleiferus). Both species showed significant increases in N2O-emissions, which differed with residue application method and soil type. N2O- emissions were generally larger in loamy soils and the strongest effect was measured for A. caliginosa when residue was mixed into the soil, increasing emissions from 1350.1 to 2223.2 micro g N2O-N kg- 1 soil. L. rubellus only resulted in elevated N2O-emissions when residue was applied on top. These studies make it

  14. Co-benefits and trade-offs in the water–energy nexus of irrigation modernization in China

    NASA Astrophysics Data System (ADS)

    Cremades, Roger; Rothausen, Sabrina G. S. A.; Conway, Declan; Zou, Xiaoxia; Wang, Jinxia; Li, Yu’e.

    2016-05-01

    There are strong interdependencies between water use in agriculture and energy consumption as water saving technologies can require increased pumping and pressurizing. The Chinese Government includes water efficiency improvement and carbon intensity reduction targets in the 12th Five-Year Plan (5YP. 2011–2015), yet the links between energy use and irrigation modernization are not always addressed in policy targets. Here we build an original model of the energy embedded in water pumping for irrigated agriculture and its related processes. The model is based on the physical processes of irrigation schemes and the implication of technological developments, comprising all processes from extraction and conveyance of water to its application in the field. The model uses data from government sources to assess policy targets for deployment of irrigation technologies, which aim to reduce water application and contribute to adaptation of Chinese agriculture to climate change. The consequences of policy targets involve co-beneficial outcomes that achieve water and energy savings, or trade-offs in which reduced water application leads to increasing greenhouse gas (GHG) emissions. We analyze irrigation efficiency and energy use in four significant provinces and nationally, using scenarios based on the targets of the 12th 5YP. At the national scale, we find that expansion of sprinklers and micro-irrigation as outlined in the 5YP would increase GHG emissions from agricultural water use, however, emissions decrease in those provinces with predominant groundwater use and planned expansion of low-pressure pipes. We show that the most costly technologies relate to trade-offs, while co-benefits are generally achieved with less expensive technologies. The investment cost per area of irrigation technology expansion does not greatly affect the outcome in terms of water, but in terms of energy the most expensive technologies are more energy-intensive and produce more emissions. The

  15. Reliable Adaptive Data Aggregation Route Strategy for a Trade-off between Energy and Lifetime in WSNs

    PubMed Central

    Guo, Wenzhong; Hong, Wei; Zhang, Bin; Chen, Yuzhong; Xiong, Naixue

    2014-01-01

    Mobile security is one of the most fundamental problems in Wireless Sensor Networks (WSNs). The data transmission path will be compromised for some disabled nodes. To construct a secure and reliable network, designing an adaptive route strategy which optimizes energy consumption and network lifetime of the aggregation cost is of great importance. In this paper, we address the reliable data aggregation route problem for WSNs. Firstly, to ensure nodes work properly, we propose a data aggregation route algorithm which improves the energy efficiency in the WSN. The construction process achieved through discrete particle swarm optimization (DPSO) saves node energy costs. Then, to balance the network load and establish a reliable network, an adaptive route algorithm with the minimal energy and the maximum lifetime is proposed. Since it is a non-linear constrained multi-objective optimization problem, in this paper we propose a DPSO with the multi-objective fitness function combined with the phenotype sharing function and penalty function to find available routes. Experimental results show that compared with other tree routing algorithms our algorithm can effectively reduce energy consumption and trade off energy consumption and network lifetime. PMID:25215944

  16. Clinical trade-offs in cross-linked ultrahigh-molecular-weight polyethylene used in total joint arthroplasty.

    PubMed

    Pruitt, Lisa A; Ansari, Farzana; Kury, Matt; Mehdizah, Amir; Patten, Elias W; Huddlestein, James; Mickelson, Dayne; Chang, Jennifer; Hubert, Kim; Ries, Michael D

    2013-04-01

    Highly cross-linked formulations of ultrahigh-molecular-weight polyethylene (XLPE) offer exceptional wear resistance for total joint arthroplasty but are offset with a reduction in postyield and fatigue fracture properties in comparison to conventional ultrahigh-molecular-weight polyethylene (UHMWPE). Oxidation resistance is also an important property for the longevity of total joint replacements (TJRs) as formulations of UHMWPE or XLPE utilizing radiation methods are susceptible to free radical generation and subsequent embrittlement. The balance of oxidation, wear, and fracture properties is an enduring concern for orthopedic polymers used as the bearing surface in total joint arthroplasty. Optimization of material properties is further challenged in designs that make use of locking mechanisms, notches, or other stress concentrations that can render the polymer susceptible to fracture due to elevated local stresses. Clinical complications involving impingements, dislocations, or other biomechanical overloads can exacerbate stresses and negate benefits of improved wear resistance provided by XLPE. This work examines trade-offs that factor into the use of XLPE in TJR implants. PMID:23436567

  17. Hydraulic limits on maximum plant transpiration and the emergence of the safety-efficiency trade-off.

    PubMed

    Manzoni, Stefano; Vico, Giulia; Katul, Gabriel; Palmroth, Sari; Jackson, Robert B; Porporato, Amilcare

    2013-04-01

    Soil and plant hydraulics constrain ecosystem productivity by setting physical limits to water transport and hence carbon uptake by leaves. While more negative xylem water potentials provide a larger driving force for water transport, they also cause cavitation that limits hydraulic conductivity. An optimum balance between driving force and cavitation occurs at intermediate water potentials, thus defining the maximum transpiration rate the xylem can sustain (denoted as E(max)). The presence of this maximum raises the question as to whether plants regulate transpiration through stomata to function near E(max). To address this question, we calculated E(max) across plant functional types and climates using a hydraulic model and a global database of plant hydraulic traits. The predicted E(max) compared well with measured peak transpiration across plant sizes and growth conditions (R = 0.86, P < 0.001) and was relatively conserved among plant types (for a given plant size), while increasing across climates following the atmospheric evaporative demand. The fact that E(max) was roughly conserved across plant types and scales with the product of xylem saturated conductivity and water potential at 50% cavitation was used here to explain the safety-efficiency trade-off in plant xylem. Stomatal conductance allows maximum transpiration rates despite partial cavitation in the xylem thereby suggesting coordination between stomatal regulation and xylem hydraulic characteristics. PMID:23356378

  18. Reliable adaptive data aggregation route strategy for a trade-off between energy and lifetime in WSNs.

    PubMed

    Guo, Wenzhong; Hong, Wei; Zhang, Bin; Chen, Yuzhong; Xiong, Naixue

    2014-01-01

    Mobile security is one of the most fundamental problems in Wireless Sensor Networks (WSNs). The data transmission path will be compromised for some disabled nodes. To construct a secure and reliable network, designing an adaptive route strategy which optimizes energy consumption and network lifetime of the aggregation cost is of great importance. In this paper, we address the reliable data aggregation route problem for WSNs. Firstly, to ensure nodes work properly, we propose a data aggregation route algorithm which improves the energy efficiency in the WSN. The construction process achieved through discrete particle swarm optimization (DPSO) saves node energy costs. Then, to balance the network load and establish a reliable network, an adaptive route algorithm with the minimal energy and the maximum lifetime is proposed. Since it is a non-linear constrained multi-objective optimization problem, in this paper we propose a DPSO with the multi-objective fitness function combined with the phenotype sharing function and penalty function to find available routes. Experimental results show that compared with other tree routing algorithms our algorithm can effectively reduce energy consumption and trade off energy consumption and network lifetime. PMID:25215944

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

    PubMed

    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

  20. Branching angles reflect a trade-off between reducing trail maintenance costs or travel distances in leaf-cutting ants.

    PubMed

    Farji-Brener, Alejandro Gustavo; Chinchilla, Federico; Umaña, María Natalia; Ocasio-Torres, Maríia Elena; Chauta-Mellizo, Alexander; Acosta-Rojas, Diana; Marinaro, Sofía; Curth, Mónica de Torres; Amador-Vargas, Sabrina

    2015-02-01

    The design of transport paths in consuming entities that use routes to access food should be under strong selective pressures to reduce costs and increase benefits. We studied the adaptive nature of branching angles in foraging trail networks of the two most abundant tropical leaf-cutting ant species. We mathematically assessed how these angles should reflect the relative weight of the pressure for reducing either trail maintenance effort or traveling distances. Bifurcation angles of ant foraging trails strongly differed depending on the location of the nests. Ant colonies in open areas showed more acute branching angles, which best shorten travel distances but create longer new trail sections to maintain than a perpendicular branch, suggesting that trail maintenance costs are smaller compared to the benefit of reduced traveling distance. Conversely, ant colonies in forest showed less acute branching angles, indicating that maintenance costs are of larger importance relative to the benefits of shortening travel distances. The trail pattern evident in forests may be attributable to huge amounts of litterfall that .increase trail maintenance costs, and the abundant canopy cover that reduces traveling costs by mitigating direct sunlight and rain. These results suggest that branching angles represent a trade-off between reducing maintenance work and shortening travel distances, illustrating how animal constructions can adjust to diverse environmental conditions. This idea may help to understand diverse networks systems, including urban travel networks. PMID:26240872

  1. Land Conservation in an Evolving Agricultural Industry: Trade-offs to Consider

    NASA Astrophysics Data System (ADS)

    Baker, J. S.; Murray, B. C.; McCarl, B. A.; Jackson, R. B.

    2008-12-01

    practices (exhibiting a 53.4% reversion rate). This reversion is a logical, low cost extensification of crop land; higher reversion rates are observed where agricultural land is most valuable, such as in Iowa and Illinois. Forecasted CRP re-cultivation accompanies environmental degradation in the form of increased chemical applications, irrigation water use and soil erosion relative to the baseline. However, if the CRP is maintained at current levels then this would shift LUC to other conversions, including a greater loss of forest amounting to 6.3 million acres relative to a case where land in CRP freely reverts. This increase in deforestation is likely to spill over into other countries as well. The net carbon loss of deforested land negates the carbon benefits of maintaining the CRP in its current state. Thus, while the environmental impacts of re-cultivating conservation lands are potentially serious, maintaining the CRP in its current form could induce LUC and even greater GHG and environmental emissions. The study concludes by discussing the environmental and economic trade-offs of land conservation under the aforementioned scenarios, and offers policy recommendations for future land conservation initiatives.

  2. Are trade-offs in plant resprouting manifested in community seed banks?

    PubMed

    Clarke, Peter J; Dorji, Kinzang

    2008-07-01

    Trade-offs in allocation to resprouting vs. seedling regeneration in plants are predicted to occur along fire disturbance gradients. Increased resprouting ability should be generally favored in plant communities with a high probability of crown fire return. Hence, communities dominated by resprouters are predicted to have smaller seed banks than those dominated by species killed by fire. We tested whether there were trait shifts in resprouting ability among growth forms (short-lived herbaceous vs. ground-dwelling perennials vs. shrubs) and among communities (rocky outcrop vs. sclerophyll forest) with contrasting probabilities of crown fire return. Resprouting was more common in ground-dwelling perennials and in the sclerophyll forest community with a high probability of crown fire. Soil seed banks were sampled in rocky outcrop and sclerophyll forest communities in recently burned (18 months) and long-since-burned (12 years) locations at interspersed replicated sites. Collected seed banks were treated with orthogonal treatments of fire stimuli or no stimuli, and seedling emergence was measured in controlled conditions. Seed bank composition reflected the pattern of extant vegetation, with resprouting species being more common in the community with a higher probability of crown fire. Overall, however, resprouting species were poorly represented in the seed bank compared to those species killed by fire. Predicted shifts in allocation to seed production were strongly manifested in community seed banks across the disturbance gradient. Fewer species, seedlings, and seedlings per adult emerged from seed banks in the sclerophyll forest. This suggests that the dominance of resprouting species influences recruitment at the community scale. Community patterns in the seed bank also reflected predicted trade-offs with plant size and growth rate. Short-lived species that are killed by fire dominated the seed bank on rocky outcrops, while longer-lived resprouting species were

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

    PubMed

    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 < 30 generations. After the lines had reached a plateau with respect to survival 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 savanna woody plant diversity and carbon storage in the Brazilian Cerrado.

    PubMed

    Pellegrini, Adam F A; Socolar, Jacob B; Elsen, Paul R; Giam, Xingli

    2016-10-01

    Incentivizing carbon storage can be a win-win pathway to conserving biodiversity and mitigating climate change. In savannas, however, the situation is more complex. Promoting carbon storage through woody encroachment may reduce plant diversity of savanna endemics, even as the diversity of encroaching forest species increases. This trade-off has important implications for the management of biodiversity and carbon in savanna habitats, but has rarely been evaluated empirically. We quantified the nature of carbon-diversity relationships in the Brazilian Cerrado by analyzing how woody plant species richness changed with carbon storage in 206 sites across the 2.2 million km(2) region at two spatial scales. We show that total woody plant species diversity increases with carbon storage, as expected, but that the richness of endemic savanna woody plant species declines with carbon storage both at the local scale, as woody biomass accumulates within plots, and at the landscape scale, as forest replaces savanna. The sharpest trade-offs between carbon storage and savanna diversity occurred at the early stages of carbon accumulation at the local scale but the final stages of forest encroachment at the landscape scale. Furthermore, the loss of savanna species quickens in the final stages of forest encroachment, and beyond a point, savanna species losses outpace forest species gains with increasing carbon accumulation. Our results suggest that although woody encroachment in savanna ecosystems may provide substantial carbon benefits, it comes at the rapidly accruing cost of woody plant species adapted to the open savanna environment. Moreover, the dependence of carbon-diversity trade-offs on the amount of savanna area remaining requires land managers to carefully consider local conditions. Widespread woody encroachment in both Australian and African savannas and grasslands may present similar threats to biodiversity. PMID:26919289

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

    PubMed

    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

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

    PubMed

    Xu, Yan-Chao; Yang, Deng-Bao; Wang, De-Hua

    2012-01-01

    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

  7. Exaggerated trait allometry, compensation and trade-offs in the New Zealand giraffe weevil (Lasiorhynchus barbicornis).

    PubMed

    Painting, Christina J; Holwell, Gregory I

    2013-01-01

    Sexual selection has driven the evolution of exaggerated traits among diverse animal taxa. The production of exaggerated traits can come at a cost to other traits through trade-offs when resources allocated to trait development are limited. Alternatively some traits can be selected for in parallel to support or compensate for the cost of bearing the exaggerated trait. Male giraffe weevils (Lasiorhynchus barbicornis) display an extremely elongated rostrum used as a weapon during contests for mates. Here we characterise the scaling relationship between rostrum and body size and show that males have a steep positive allometry, but that the slope is non-linear due to a relative reduction in rostrum length for the largest males, suggesting a limitation in resource allocation or a diminishing requirement for large males to invest increasingly into larger rostra. We also measured testes, wings, antennae, fore- and hind-tibia size and found no evidence of a trade-off between these traits and rostrum length when comparing phenotypic correlations. However, the relative length of wings, antennae, fore- and hind-tibia all increased with relative rostrum length suggesting these traits may be under correlational selection. Increased investment in wing and leg length is therefore likely to compensate for the costs of flying with, and wielding the exaggerated rostrum of larger male giraffe weevils. These results provide a first step in identifying the potential for trait compensation and trades-offs, but are phenotypic correlations only and should be interpreted with care in the absence of breeding experiments. PMID:24312425

  8. No Evidence for a Trade-Off between Reproductive Investment and Immunity in a Rodent

    PubMed Central

    Xu, Yan-Chao; Yang, Deng-Bao; Wang, De-Hua

    2012-01-01

    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

  9. Early developmental exposures shape trade-offs between acquired and innate immunity in humans

    PubMed Central

    Georgiev, Alexander V.; Kuzawa, Christopher W.; McDade, Thomas W.

    2016-01-01

    Background and objectives Life history theory predicts resource allocation trade-offs between competing functions and processes. We test the hypothesis that relative investment towards innate versus acquired immunity in humans is subject to such trade-offs and that three types of early developmental exposures are particularly salient in shaping adult immunophenotype: (i) pathogen exposure, (ii) nutritional resources; and (iii) extrinsic mortality cues. Methodology We quantified one aspect each of innate and acquired immune function, via C-reactive protein and Epstein–Barr virus antibodies, respectively, in a sample of 1248 men and women from the Philippines (ca. 21.5 years old). Early developmental exposures were assessed via long-term data collected prospectively since participants’ birth (1983–4). We calculated a standardized ratio to assess relative bias towards acquired versus innate immune function and examined its relationship to a suite of predictors via multiple regression. Results In partial support of our predictions, some of the measures of higher pathogen exposure, greater availability of nutritional resources, and lower extrinsic mortality cues in early life were associated with a bias toward acquired immunity in both men and women. The immune profile of women, in particular, appeared to be more sensitive to early life pathogen exposures than those of men. Finally, contrary to prediction, women exhibited a greater relative investment toward innate, not acquired, immunity. Conclusions and implications Early environments can exert considerable influence on the development of immunity. They affect trade-offs between innate and acquired immunity, which show adaptive plasticity and may differ in their influence in men and women. PMID:27530543

  10. Ecological Implications of a Flower Size/Number Trade-Off in Tropical Forest Trees

    PubMed Central

    Kettle, Chris J.; Maycock, Colin R.; Ghazoul, Jaboury; Hollingsworth, Pete M.; Khoo, Eyen; Sukri, Rahayu Sukmaria Haji; Burslem, David F. R. P.

    2011-01-01

    Background In angiosperms, flower size commonly scales negatively with number. The ecological consequences of this trade-off for tropical trees remain poorly resolved, despite their potential importance for tropical forest conservation. We investigated the flower size number trade-off and its implications for fecundity in a sample of tree species from the Dipterocarpaceae on Borneo. Methodology/Principal Findings We combined experimental exclusion of pollinators in 11 species, with direct and indirect estimates of contemporary pollen dispersal in two study species and published estimates of pollen dispersal in a further three species to explore the relationship between flower size, pollinator size and mean pollen dispersal distance. Maximum flower production was two orders of magnitude greater in small-flowered than large-flowered species of Dipterocarpaceae. In contrast, fruit production was unrelated to flower size and did not differ significantly among species. Small-flowered species had both smaller-sized pollinators and lower mean pollination success than large-flowered species. Average pollen dispersal distances were lower and frequency of mating between related individuals was higher in a smaller-flowered species than a larger-flowered confamilial. Our synthesis of pollen dispersal estimates across five species of dipterocarp suggests that pollen dispersal scales positively with flower size. Conclusions and Their Significance Trade-offs embedded in the relationship between flower size and pollination success contribute to a reduction in the variance of fecundity among species. It is therefore plausible that these processes could delay competitive exclusion and contribute to maintenance of species coexistence in this ecologically and economically important family of tropical trees. These results have practical implications for tree species conservation and restoration. Seed collection from small-flowered species may be especially vulnerable to cryptic genetic