543 research outputs found

    The positive and negative consequences of stressors during early life

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    We discuss the long-term effects of stress exposure in pre- and early postnal life. We present an evolutionary framework within which such effects can be viewed, and describe how the outcomes might vary with species life histories. We focus on stressors that induce increases in glucocorticoid hormones and discuss the advantages of an experimental approach. We describe a number of studies demonstrating how exposure to these hormones in early life can influence stress responsiveness and have substantial long-term, negative consequences for adult longevity. We also describe how early life exposure to mild levels of stressors can have beneficial effects on resilience to stress in later life, and discuss how the balance of costs and benefits is likely dependent on the nature of the adult environment

    Variation in early-life telomere dynamics in a long-lived bird: links to environmental conditions and survival

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    Conditions experienced during early life can have profound consequences for both short and long-term fitness. Variation in the natal environment has been shown to influence survival and reproductive performance of entire cohorts in wild vertebrate populations. Telomere dynamics potentially provide a link between the early environment and long-term fitness outcomes, yet we know little about how the environment can influence telomere dynamics in early life. We found that environmental conditions during growth have an important influence on early-life telomere length (TL) and attrition in nestlings of a long-lived bird, the European storm petrel Hydrobates pelagicus. Nestlings reared under unfavourable environmental conditions experienced significantly greater telomere loss during postnatal development compared with nestlings reared under more favourable natal conditions, which displayed a negligible change in TL. There was, however, no significant difference in pre-fledging TL between cohorts. The results suggest that early-life telomere dynamics could contribute to the marked differences in life-history traits that can arise among cohorts reared under different environmental conditions. Early-life TL was also found to be a significant predictor of survival during the nestling phase, providing further evidence for a link between variation in TL and individual fitness. To what extent the relationship between early-life TL and mortality during the nestling phase is a consequence of genetic, parental and environmental factors is currently unknown, but an interesting area for future research. Accelerated telomere attrition under unfavourable conditions, as observed in this study, might play a role in mediating the effects of the early-life environment on later-life performance

    Variation in population synchrony in a multi-species seabird community: response to changes in predator abundance

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    Ecologically similar sympatric species, subject to typical environmental conditions, may be expected to exhibit synchronous temporal fluctuations in demographic parameters, while populations of dissimilar species might be expected to show less synchrony. Previous studies have tested for synchrony in different populations of single species, and those including data from more than one species have compared fluctuations in only one demographic parameter. We tested for synchrony in inter-annual changes in breeding population abundance and productivity among four tern species on Coquet Island, northeast England. We also examined how manipulation of one independent environmental variable (predator abundance) influenced temporal changes in ecologically similar and dissimilar tern species. Changes in breeding abundance and productivity of ecologically similar species (Arctic Sterna paradisaea, Common S. hirundo and Roseate Terns S. dougallii) were synchronous with one another over time, but not with a species with different foraging and breeding behaviour (Sandwich Terns Thalasseus sandvicensis). With respect to changes in predator abundance, there was no clear pattern. Roseate Tern abundance was negatively correlated with that of large gulls breeding on the island from 1975 to 2013, while Common Tern abundance was positively correlated with number of large gulls, and no significant correlations were found between large gull and Arctic and Sandwich Tern populations. Large gull abundance was negatively correlated with productivity of Arctic and Common Terns two years later, possibly due to predation risk after fledging, while no correlation with Roseate Tern productivity was found. The varying effect of predator abundance is most likely due to specific differences in the behaviour and ecology of even these closely-related species. Examining synchrony in multi-species assemblages improves our understanding of how whole communities react to long-term changes in the environment and suggests that changes in predator abundance may differentially affect populations of sympatric seabird species

    Allocating SMART Reliability and Maintainability Goals to NASA Ground Systems

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    This paper will describe the methodology used to allocate Reliability and Maintainability (R&M) goals to Ground Systems Development and Operations (GSDO) subsystems currently being designed or upgraded

    Evidence-based policy and policy as ‘translation’: designing a model for policymaking

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    The EU referendum campaign and aftermath brought to the fore the ongoing debate about evidence and evidence-based policymaking (EBPM), write Jo Ingold and Mark Monaghan. While Michael Gove’s suggestion that “people in this country have had enough of experts” could be seen as a rebuttal to criticisms of the Leave campaign’s misuse of statistics, it also draws attention not only to what counts as evidence but also to the perceived gap between ‘the academy’, policymakers and the public

    Mixing drink and drugs: ‘underclass’ politics, the recovery agenda and the partial convergence of English alcohol and drugs policy

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    Alcohol policy and illicit drugs policy are typically presented as separate and different in academic discussion. This is understandable, to a degree, as the criminal law upholds a ‘great regulatory divide’ (Seddon) separating the licit trade in alcohol from the illicit trade in substances classified as either class A, B or C under the Misuse of Drugs Act 1971. This paper takes a different stance. In doing so, it draws upon Berridge's argument that policies governing various psychoactive substances have been converging since the mid-twentieth century and seeks to elaborate it using recent developments relating to the control and regulation of drugs and alcohol in the broader areas of criminal justice and welfare reform. Significantly, the article examines how recent policy directions relating to both drugs and alcohol in England have, under the aegis of the ‘recovery agenda’, been connected to a broader behavioural politics oriented towards the actions and lifestyles of an apparently problematic subgroup of the population or ‘underclass’. The paper thus concludes that, although the great regulatory divide remains intact, an underclass politics is contributing towards the greater alignment of illicit drugs and alcohol policies, especially in regards to the respective significance of abstinence (or abstinence-based ‘recovery’)

    Rethinking recovery and desistance processes: Developing a social identity model of transition

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    Background: In recent years, the role of social identity (or identities which are developed through involvement in social groups with others), has received increasing attention in relation to recovery from substance abuse disorders. However, it is also widely noted that the transformation of one’s social identitie(s) is vital for the cessation of other, non-addictive behaviours, such as offending. Interestingly, the discussion of the role of social identity transformation in relation to both desistance and recovery simultaneously has seldom been undertaken. Methods: Drawing on primary research consisting of 20 double narrative interviews with young adult offenders on an Intensive Community Order, the paper builds upon the two most prominent social identity models surrounding addictive behaviour, the Social Identity Model of Recovery and the Social Identity Model of Cessation Maintenance in order to develop a social identity model which aids our understanding of desistance and recovery processes. Results: The paper presents a Social Identity Model of Transition (SIMOT), allowing for the synergies between desistance and recovery as processes of transition to come to light. Conclusion: SIMOT allows for an understanding of the role of social identity transformation in the transient nature of desistance and recovery processes. The model allows for an examination of the impact of macro and micro contextual factors on desistance and recovery processes in a way which has seldom been possible with the currently available models

    Development of Hybrid Product Breakdown Structure for NASA Ground Systems

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    The Product Breakdown Structure is traditionally a method of identification of the products of a project in a tree structure. It is a tool used to assess, plan, document, and display the equipment requirements for a project. It is part of a product based planning technique, and attempts to break down all components of a project in as much detail as possible, so that nothing is overlooked. The PBS for ground systems at the Kennedy Space Center is being developed to encompass the traditional requirements including the alignment of facility, systems, and components to the organizational hierarchy. The Ground Operations Product Breakdown Structure is a hybrid in nature in that some aspects of a work breakdown structure will be incorporated and merged with the Architecture Concept of Operations, Master Subsystem List, customer interface, and assigned management responsibility. The Ground Operations Product Breakdown Structure needs to be able to identify the flexibility of support differing customers (internal and external) usage of ground support equipment within the Kennedy Space Center launch and processing complex. The development of the Product Breakdown Structure is an iterative activity Initially documenting the organization hierarchy structure and relationships. The Product Breakdown Structure identifies the linkage between the customer program requirements, allocation of system resources, development of design goals, and identification logistics products. As the Product Breakdown Structure progresses the incorporation of the results of requirement planning for the customer occurs identifying facility needs and systems. The mature Product Breakdown Structure is baselined with a hierarchical drawing, the Product Breakdown Structure database, and an associated document identifying the verification of the data through the life cycle of the program/product line. This paper will document, demonstrate, and identify key aspects of the life cycle of a Hybrid Product Breakdown Structure. The purpose is to show how a project management and system engineering approach can be utilized for providing flexible customer service in an evolving manned space flight launch processing environment

    Parental resource allocation among offspring varies with increasing brood age in Black-legged Kittiwakes Rissa tridactyla

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    Capsule: Black-legged Kittiwakes Rissa tridactyla breeding at a North Sea colony allocated more resources to younger chicks with increasing brood age.<p></p> Aims: Examine how feeding, attendance and resource allocation change with increasing brood age and how allocation of feeds affects growth rate and fledging success.<p></p> Methods: Broods of two were observed on Coquet Island to compare feeding rates and fledging success between chicks of different hatching order.<p></p> Results: Growth and feeding rates were similar between chicks of different hatching order. The relationship between growth and feeding rate may have differed between siblings, although this relationship was not strong. Feeding rate per brood and nest attendance decreased nonlinearly as brood age increased. First-hatched chicks were fed more frequently at the beginning of multiple feeds and received a higher proportion of feeds during early chick-rearing. However, during late chick-rearing second-hatched chicks received proportionally more feeds.<p></p> Conclusion: Parents reduced overall feeding rate as brood age increased, while increasing the proportion of resources allocated to younger offspring. This may explain general similarities in growth rate and fledging success between chicks of different hatching order. By considering resource allocation throughout development we can better understand parental investment strategies in asynchronous species.<p></p&gt
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