6,769 research outputs found

    The Evolution of Male-Biased Dispersal under the Joint Selective Forces of Inbreeding Load and Demographic and Environmental Stochasticity

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    Acknowledgments We thank G. Bocedi, S. Palmer, and three anonymous reviewers for helpful comments on earlier drafts. R.C.H. was funded by the Natural Environment Research Council (1271380). Simulations were performed on the University of Aberdeen’s Maxwell high performance computing cluster.Peer reviewedPublisher PD

    Grassland Management and Animal Product Quality

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    The expectations of consumers ultimately determine the specification of product quality; and grassland systems produce a wide range of animal-based products. Therefore, to provide focus, this paper deals only with food products that are destined for markets that exhibit strong discretionary choice. Quality expectations of consumers have traditionally been based on product attributes such as taste, freshness, nutritional value and appearance, but customer expectations are expanding to encompass food safety, environmental care, animal welfare and biotechnologies. Grassland forages and their management influence the intrinsic sensory properties of food. A dairy products case study is presented, indicating that pasture species and their interaction with local environmental factors, and the methods of forage conservation, can influence the chemical composition of milk, its ability to be processed into butter or cheese, and the final sensory characteristics of the product. These effects may result directly from compounds originating in the forage (e.g. carotenoids, aromatic terpenes) or indirectly through forage-related changes in animal physiology and enzyme production. Knowledge of these influences and the strict control of the determining factors are key elements in the granting of Protected Denomination of Origin (DMO) status and the benefits that accrue from marketing strategies that depend on this status. Animal feeding regimes also influence the attributes of meat. Pasture-grazed animals have harder and yellower carcass fat than grain-fed animals. The daily energy intake of pasture-grazed animals is also generally lower; therefore there is less intra-muscular marbling. In addition, glycogen levels tend to be more marginal, which can negatively interact with psychological stress to produce a greater incidence of high ultimate pH carcasses. High pH levels (\u3e 5.8) result in reduced tenderness, dark muscle and reduced shelf-life of fresh and chilled meats. Early identification of product quality variation is key to placing meat into the correct supply chain, and maximising the total value of the carcass. The positive and negative aspects of fatty acid profiles, phenol and indole compounds, and antioxidants originating from forages are discussed in respect of meat flavour and animal health. Tight planning and management protocols for both plants and animals are crucial to achieving quality raw material from grassland systems. Unlike feedlot and barn-based enterprises, variation in forage quantity and quality can severely impact on animal performance, timeliness of supply and raw product constituents. Control of a forage-based system requires the setting of performance targets and on-going monitoring. Such measures can signal when the tactical use of specialist forages, or of high-quality supplements, will be of most value in maintaining target performance and animal health. Consistently supplying products with desired attributes, attending to animal welfare expectations and caring for environmental integrity will all be required if the credibility of ‘natural’ grassland products is to be sustained in the market-place. Controlled grazing of animals will be invaluable in meeting these multiple market demands

    A stochastic movement simulator improves estimates of landscape connectivity

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    Acknowledgments This publication issued from the project TenLamas funded by the French Ministère de l'Energie, de l'Ecologie, du Développement Durable et de la Mer through the EU FP6 BiodivERsA Eranet; by the Agence Nationale de la Recherche (ANR) through the open call INDHET and 6th extinction MOBIGEN to V. M. Stevens, M. Baguette, and A. Coulon, and young researcher GEMS (ANR-13-JSV7-0010-01) to V. M. Stevens and M. Baguette; and by a VLIR-VLADOC scholarship awarded to J. Aben. L. Lens, J. Aben, D. Strubbe, and E. Matthysen are grateful to the Research Foundation Flanders (FWO) for financial support of fieldwork and genetic analysis (grant G.0308.13). V. M. Stevens and M. Baguette are members of the “Laboratoire d'Excellence” (LABEX) entitled TULIP (ANR-10-LABX-41). J. M. J. Travis and S. C. F. Palmer also acknowledge the support of NERC. A. Coulon and J. Aben contributed equally to the work.Peer reviewedPublisher PD

    MCMC Algorithms for Supervised and Unsupervised Linear Unmixing of Hyperspectral Images

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    This book is a collection of 19 articles which reflect the courses given at the Collège de France/Summer school “Reconstruction d'images − Applications astrophysiques“ held in Nice and Fréjus, France, from June 18 to 22, 2012. The articles presented in this volume address emerging concepts and methods that are useful in the complex process of improving our knowledge of the celestial objects, including Earth

    ADAPT: a price-stabilizing compliance policy for renewable energy certificates: the case of SREC markets

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    Currently most Renewable Energy Certificate (REC) markets are defined based on targets which create an artificial step demand function resembling a cliff. This target policy produces volatile prices which can make investing in renewables a risky proposition. In this paper, we propose an alternative policy called Adjustable Dynamic Assignment of Penalties and Targets (ADAPT) which uses a sloped compliance penalty and a self-regulating requirement schedule, both designed to stabilize REC prices, helping to alleviate a common weakness of environmental markets. To capture market behavior, we model the market as a stochastic dynamic programming problem to understand how the market might balance the decision to use a REC now versus holding it for future periods (in the face of uncertain new supply). Then, we present and prove some of the properties of this market, and finally we show that this mechanism reduces the volatility of REC prices which should stabilize the market and encourage long-term investment in renewables

    An ensemble-based approach for pumping optimization in an island aquifer considering parameter, observation and climate uncertainty

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    In coastal zones, a major objective of groundwater management is often to determine sustainable pumping rates which avoid well salinization. Understanding how model and climate uncertainties affect optimal management solutions is essential for providing groundwater managers with information about salinization risk and is facilitated by the use of optimization under uncertainty (OUU) methods. However, guidelines are missing for the widespread implementation of OUU in real-world coastal aquifers and for the incorporation of climate uncertainty into OUU approaches. An ensemble-based OUU approach was developed considering parameter, observation and climate uncertainty and was implemented in a real-world island aquifer in the Magdalen Islands (Quebec, Canada). A sharp-interface seawater intrusion model was developed using MODFLOW-SWI2 and a prior parameter ensemble was generated containing multiple equally plausible realizations. Ensemble-based history matching was conducted using an iterative ensemble smoother which yielded a posterior parameter ensemble conveying both parameter and observation uncertainty. Sea level and recharge ensembles were generated for the year 2050 and were then used to generate a predictive parameter ensemble conveying parameter, observation and climate uncertainty. Multi-objective OUU was then conducted, aiming to both maximize pumping rates and minimize the probability of well salinization. As a result, the optimal trade-off between pumping and the probability of salinization was quantified considering parameter, historical observation and future climate uncertainty simultaneously. The multi-objective, ensemble-based OUU led to optimal pumping rates that were very different from a previous deterministic OUU and close to the current and projected water demand for risk-averse stances. Incorporating climate uncertainty into the OUU was also critical since it reduced the maximum allowable pumping rates for users with a risk-averse stance. The workflow used tools adapted to very high-dimensional, nonlinear models and optimization problems to facilitate its implementation in a wide range of real-world settings.</p
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