Practical guidelines for modelling post-entry spread in invasion ecology

In this article we review a variety of methods to enable understanding and modelling the spread of a pest or pathogen post-entry. Building upon our experience of multidisciplinary research in this area, we propose practical guidelines and a framework for model development, to help with the application of mathematical modelling in the field of invasion ecology for post-entry spread. We evaluate the pros and cons of a range of methods, including references to examples of the methods in practice. We also show how issues of data deficiency and uncertainty can be addressed. The aim is to provide guidance to the reader on the most suitable elements to include in a model of post-entry dispersal in a risk assessment, under differing circumstances. We identify both the strengths and weaknesses of different methods and their application as part of a holistic, multidisciplinary approach to biosecurity research

A comparative analysis of parallel processing and super-individual methods for improving the computational performance of a large individual-based model

Individual-based modelling approaches are being used to simulate larger complex spatial systems in ecology and in other fields of research. Several novel model development issues now face researchers: in particular how to simulate large numbers of individuals with high levels of complexity, given finite computing resources. A case study of a spatially-explicit simulation of aphid population dynamics was used to assess two strategies for coping with a large number of individuals: the use of ‘super-individuals’ and parallel computing. Parallelisation of the model maintained the model structure and thus the simulation results were comparable to the original model. However, the super-individual implementation of the model caused significant changes to the model dynamics, both spatially and temporally. When super-individuals represented more than around 10 individuals it became evident that aggregate statistics generated from a super-individual model can hide more detailed deviations from an individual-level model. Improvements in memory use and model speed were perceived with both approaches. For the parallel approach, significant speed-up was only achieved when more than five processors were used and memory availability was only increased once five or more processors were used. The super-individual approach has potential to improve model speed and memory use dramatically, however this paper cautions the use of this approach for a density-dependent spatially-explicit model, unless individual variability is better taken into account

The quality of pork roasts as influenced by the feeding of antibiotics to hogs

Call number: LD2668 .T4 1955 P37Master of Scienc

Effects of land management upon species population dynamics: a spatially explicit, individual-based model

Individual-based approaches in ecology provide a new approach to spatially explicit modelling. They are paralleled by the emergence of agent-based modelling in the field of artificial intelligence (AI) that is manifest in object-based approaches in a number of geographical disciplines, from hydrology to sociology. An individual-based approach to the simulation of organisms in a spatial context allows for a greater understanding of how individual-level behaviour and interactions result in population-level phenomena at the landscape-scale. Such models are inherently flexible and adaptable to other species or systems, and the model can be parameterised from biological behavioural information widely available in the literature. This research constructs, analyses and experiments with an individual-based model of aphid (Rhopalosiphum padi) population dynamics in agricultural landscapes during the autumn and winter. The model combines deterministic equations governing the development of the aphids with stochastic, behavioural rules. Several stages of model assessment validate the model: assessment at the conceptual, developmental and operational stages. The need for a solution for the model to cope with large population sizes led to experimentation with both mathematical and computational solutions to this problem. It was found that parallel computing to distribute the simulation across a 30-node Beowulf cluster was the most effective at increasing model efficiency whilst preserving model behaviour. Key scenarios are presented, that show the power of this approach in predicting potential impacts of agricultural landscape change, including the effects of crop management, marginal habitat configuration and pesticide regime. This research clearly demonstrates the potential of spatially explicit individual-based modelling to predict scenarios that may advise policy decision-makers as a landscape management tool

Tipping the scales: ambidexterity practices on e-HRM projects

Purpose: We examine and conceptualise the ways in which a balance can be achieved between optimising the efficiency and effectiveness of electronic HRM (e-HRM) systems for human resource management (HRM) and enabling innovation to occur during the system implementation. Design/methodology/approach: An intepretive case study of a UK local authority e-HRM system implementation is examined using the notion of ambidexterity as an analytical device. Ambidexterity relates to how an organisation develops the ability to operate efficiently in the now, while at the same time being able to adapt to environmental changes around and ahead of them in order to grow into the future. Findings: As an intra-organisational capability, ambidexterity is found to derive from the simultaneous interplay and balancing of dual capabilities: exploitation and exploration.. E-HRM exploitation concerned the capability to generate new knowledge with innovatory effects, created through the everyday practices performed by practitioners at all levels in the organisation. E-HRM exploration, rather than being a purposeful act, was found to be an accidental consequence of engaging in exploitation to maintain the status quo. Originality/value: There is a lack of detailed investigation of how organisations actually achieve ambidexterity, particularly in three under-researched areas: ambidexterity in the public sector, at HR functional level and e-HRM systems implementation. Bundling these three areas into an integrated examination allows us to both identify how exploitation and exploration play out in the ambidextrous practices of an e-HRM project and also to identify the dimensions of ambidexterity in balancing e-HRM work

Optimal L\'{e}vy-flight foraging in a finite landscape

We present a simple model to study L\'{e}vy-flight foraging in a finite landscape with countable targets. In our approach, foraging is a step-based exploratory random search process with a power-law step-size distribution $P(l) \propto l^{-\mu}$. We find that, when the termination is regulated by a finite number of steps $N$, the optimum value of $\mu$ that maximises the foraging efficiency can vary substantially in the interval $\mu \in (1,3)$, depending on the landscape features (landscape size and number of targets). We further demonstrate that subjective returning can be another significant factor that affects the foraging efficiency in such context. Our results suggest that L\'{e}vy-flight foraging may arise through an interaction between the environmental context and the termination of exploitation, and particularly that the number of steps can play an important role in this scenario which is overlooked by most previous work. Our study not only provides a new perspective on L\'{e}vy-flight foraging, but also opens new avenues for investigating the interaction between foraging dynamics and environment as well as offers a realistic framework for analysing animal movement patterns from empirical data.Comment: 25 pages, 6 figure

University sports clubs: culture, belonging and adapting to change during COVID-19

It is commonly accepted that there are many physical, social and psychological benefits to participating in extracurricular activities at university. While there is a growing body of literature that considers the role of extracurricular activities in enhancing the student experience and fostering better university outcomes, the role that sports clubs play specifically is largely missing from the literature. What is more, the value of sport was highlighted when it was removed during the COVID-19 pandemic. Therefore, this paper draws on doctoral research into the experiences of university sports club members during the COVID-19 pandemic, particularly surrounding the recreation of the social practices that make up sports club culture, via online communities. Through adopting a Bourdieusian perspective, this paper explores the impact of university sports clubs on students’ identity formation and sense of belonging