6 resultados para Behaviour, social insects, parasites, host defense, coevolution

em Aston University Research Archive


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Multi-agent algorithms inspired by the division of labour in social insects are applied to a problem of distributed mail retrieval in which agents must visit mail producing cities and choose between mail types under certain constraints.The efficiency (i.e. the average amount of mail retrieved per time step), and the flexibility (i.e. the capability of the agents to react to changes in the environment) are investigated both in static and dynamic environments. New rules for mail selection and specialisation are introduced and are shown to exhibit improved efficiency and flexibility compared to existing ones. We employ a genetic algorithm which allows the various rules to evolve and compete. Apart from obtaining optimised parameters for the various rules for any environment, we also observe extinction and speciation. From a more theoretical point of view, in order to avoid finite size effects, most results are obtained for large population sizes. However, we do analyse the influence of population size on the performance. Furthermore, we critically analyse the causes of efficiency loss, derive the exact dynamics of the model in the large system limit under certain conditions, derive theoretical upper bounds for the efficiency, and compare these with the experimental results.

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Multi-agent algorithms inspired by the division of labour in social insects and by markets, are applied to a constrained problem of distributed task allocation. The efficiency (average number of tasks performed), the flexibility (ability to react to changes in the environment), and the sensitivity to load (ability to cope with differing demands) are investigated in both static and dynamic environments. A hybrid algorithm combining both approaches, is shown to exhibit improved efficiency and robustness. We employ nature inspired particle swarm optimisation to obtain optimised parameters for all algorithms in a range of representative environments. Although results are obtained for large population sizes to avoid finite size effects, the influence of population size on the performance is also analysed. From a theoretical point of view, we analyse the causes of efficiency loss, derive theoretical upper bounds for the efficiency, and compare these with the experimental results.

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In this study, we examine Chinese host country nationals' (HCNs') willingness to offer role information and social support to expatriates from the United States. Using data from 132 Chinese managers, we find that ethnocentrism, interpersonal affect, and guanxi significantly impact HCNs' willingness to offer help to expatriates. Furthermore, we find that the job level of the expatriate has a significant impact on HCNs' willingness to offer role information but not on willingness to offer social support. The results suggest that paying attention to the perceptions and reactions of HCNs toward expatriates is imperative for multinational companies if expatriates are to succeed on their assignments. ©2011 Wiley Periodicals, Inc.

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This thesis is about the discretionary role of the line manager in inspiring the work engagement of staff and their resulting innovative behaviour examined through the lens of Social Exchange Theory (Blau, 1964) and the Job Demands-Resources theory (Bakker, Demerouti, Nachreiner & Schaufeli, 2001). The study is focused on a large British Public Sector organisation undergoing a major organisational shift in the way in which they operate as part of the public sector. It is often claimed that people do not leave organisations; they leave line managers (Kozlowski & Doherty, 1989). Regardless of the knowledge in the literature concerning the importance of the line manager in organisations (Purcell, 2003), the engagement literature in particular is lacking in the consideration of such a fundamental figure in organisational life. Further, the understanding of the black box of managerial discretion and its relationship to employee and organisation related outcomes would benefit from greater exploration (Purcell, 2003; Gerhart, 2005; Scott, et al, 2009). The purpose of this research is to address these gaps with relation to the innovative behaviour of employees in the public sector – an area that is not typically associated with the public sector (Bhatta, 2003; McGuire, Stoner & Mylona, 2008; Hughes, Moore & Kataria, 2011). The study is a CASE Award PhD thesis, requiring academic and practical elements to the research. The study is of one case organisation, focusing on one service characterised by a high level of adoption of Strategic Human Resource Management activities and operating in a rather unique manner for the public sector, having private sector competition for work. The study involved a mixed methods approach to data collection. Preliminary focus groups with 45 participants were conducted, followed by an ethnographic period of five months embedded into the service conducting interviews and observations. This culminated in a quantitative survey delivered within the wider directorate to approximately 500 staff members. The study used aspects of the Grounded Theory (Glaser & Strauss, 1967) approach to analyse the data and developed results that highlight the importance of the line manager in an area characterised by SHRM and organisational change for engaging employees and encouraging innovative behaviour. This survey was completed on behalf of the organisation and the findings of this are presented in appendix 1, in order to keep the focus of the PhD on theory development. Implications for theory and practice are discussed alongside the core finding. Line managers’ discretion surrounding the provision of job resources (in particular trust, autonomy and implementation and interpretation of combined bundles of SHRM policies and procedures) influenced the exchange process by which employees responded with work engagement and innovative behaviour. Limitations to the research are the limitations commonly attributed to cross-sectional data collection methods and those surrounding generalisability of the qualitative findings outside of the contextual factors characterising the service area. Suggestions for future research involve addressing these limitations and further exploration of the discretionary role with regards to extending our understanding of line manager discretion.

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Increasing the supply of entrepreneurs reduces unemployment and accelerates economic growth (Acs, 2006; Audretsch, 2007; Santarelli et el. 2009; Campbell, 1996; Carree & Thurik, 1996). The supply of entrepreneurs depends on the entrepreneurial intention and activity of the people (Kruger & Brazeal, 1994). Existing behavioural theories explain that entrepreneurial activity is an attitude driven process which is mediated by intention and regulated by behavioural control. These theories are: Theory of Planned Behaviour (Ajzen, 1991; 2002, 2012); Entrepreneurial Event Model (Shapiro & Shokol, 1982), and Social Cognitive Theory (Bandura, 1977; 1986; 2012). Meta-analysis of existing behavioural theories in different fields found that the theories are more effective to analyse behavioural intention and habitual behaviour, but less effective to analyse long-term and risky behaviour (McEachan et al., 2011). The objective of this dissertation is to improve entrepreneurship behaviour theory to advance our understanding of the determinants of the entrepreneurial intention and activity. To achieve this objective we asked three compelling questions in our research. These are: Firstly, why do differences exist in entrepreneurship among age groups. Secondly, how can we improve the theory to analyse entrepreneurial intention and behaviour? And, thirdly, is there any relationship between counterfactual or regretful thinking and entrepreneurial intention? We address these three questions in Chapters 2, 3 and 4 of the dissertation. Earlier studies have identified that there is an inverse U shaped relationship between age and entrepreneurship (Parker, 2004; Hart et al., 2004). In our study, we explain the reasons for this inverse U shape (Chapter 2). To analyse the reasons we use Cognitive Life Cycle theory and Disuse theory. We assume that the stage in the life cycle of an individual moderates the influence of opportunity identification and skill to start a business. In our study, we analyse the moderation effect in early stage entrepreneurship and in serial entrepreneurship. In Chapter 3, the limitations of existing psychological theories are discussed, and a competency value theory of entrepreneurship (CVTE) is proposed to overcome the limitations and extend existing theories. We use a ‘weighted competency’ variable instead of a ‘perceived behavioural control’ variable for the theory of planned behaviour (TPB) and self-efficacy variable for social cognitive theory. Weighted competency is the perceived competency ranking assigned by an individual for his total competencies to be an entrepreneur. The proposed theory was tested in a pilot survey in the UK and in a national adult population survey in a South Asian Country. The results show a significant relationship between competencies and entrepreneurial intention, and weighted competencies and entrepreneurial behaviour as per CVTE. To improve the theory further, in Chapter 4, we test the relationship between counterfactual thinking and entrepreneurial intention. Studies in cognitive psychology identify that ‘upward counterfactual thinking’ influences intention and behaviour (Epstude & Rose, 2008; Smallman & Roese, 2009). Upward counterfactual thinking is regretful thinking for missed opportunities of a problem. This study addresses the question of how an individual’s regretful thinking affects his or her future entrepreneurial career intention. To do so, we conducted a study among students in a business school in the UK, and we found that counterfactual thinking modifies the influence of attitude and opportunity identification in entrepreneurial career intention.