University of Exeter

About: University of Exeter is a education organization based out in Exeter, United Kingdom. It is known for research contribution in the topics: Population & Climate change. The organization has 15820 authors who have published 50650 publications receiving 1793046 citations. The organization is also known as: Exeter University & University of the South West of England.

A meta-analysis of experiments testing the effects of a neonicotinoid insecticide (imidacloprid) on honey bees

Abstract: Honey bees provide important pollination services to crops and wild plants. The agricultural use of systemic insecticides, such as neonicotinoids, may harm bees through their presence in pollen and nectar, which bees consume. Many studies have tested the effects on honey bees of imidacloprid, a neonicotinoid, but a clear picture of the risk it poses to bees has not previously emerged, because investigations are methodologically varied and inconsistent in outcome. In a meta-analysis of fourteen published studies of the effects of imidacloprid on honey bees under laboratory and semi-field conditions that comprised measurements on 7073 adult individuals and 36 colonies, fitted dose–response relationships estimate that trace dietary imidacloprid at field-realistic levels in nectar will have no lethal effects, but will reduce expected performance in honey bees by between 6 and 20%. Statistical power analysis showed that published field trials that have reported no effects on honey bees from neonicotinoids were incapable of detecting these predicted sublethal effects with conventionally accepted levels of certainty. These findings raise renewed concern about the impact on honey bees of dietary imidacloprid, but because questions remain over the environmental relevance of predominantly laboratory-based results, I identify targets for research and provide procedural recommendations for future studies.

On Geography and Materiality

Abstract: In the context of human geography's encounter with the problematics that surround matter and materiality, this paper offers a principle that works towards a distinctive material imagination. This principle states that our image of matter should be multiplied, so that it can be attended to as taking place with the properties and capacities of any element or state. We elaborate this principle through three substantive discussions of materiality as turbulent, as interrogative, and as excessive. In doing so we draw upon, in turn, forms of relational materialism associated with actor-network theory, the postphenomenologies of Lingis, the animate or enchanted materialism developed by Bennett, and the figurative and affective (im)materialities of Deleuze. The conclusion clarifies why we do not call for geography to be ‘rematerialised’.

The impact of temperature on marine phytoplankton resource allocation and metabolism

Abstract: The effect of temperature on marine phytoplankton growth strategies, metabolism and composition is studied using a range of techniques. This approach indicates that temperature plays a previously unrecognized, critical role in resource allocation and marine phytoplankton elemental ratios, with implications for biogeochemical cycling.

Self-adaptive fitness formulation for constrained optimization

Abstract: A self-adaptive fitness formulation is presented for solving constrained optimization problems. In this method, the dimensionality of the problem is reduced by representing the constraint violations by a single infeasibility measure. The infeasibility measure is used to form a two-stage penalty that is applied to the infeasible solutions. The performance of the method has been examined by its application to a set of eleven test cases from the specialized literature. The results have been compared with previously published results from the literature. It is shown that the method is able to find the optimum solutions. The proposed method requires no parameter tuning and can be used as a fitness evaluator with any evolutionary algorithm. The approach is also robust in its handling of both linear and nonlinear equality and inequality constraint functions. Furthermore, the method does not require an initial feasible solution.