998 resultados para context switch


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We develop a theory for the food intake of a predator that can switch between multiple prey species. The theory addresses empirical observations of prey switching and is based on the behavioural assumption that a predator tends to continue feeding on prey that are similar to the prey it has consumed last, in terms of, e.g., their morphology, defences, location, habitat choice, or behaviour. From a predator's dietary history and the assumed similarity relationship among prey species, we derive a general closed-form multi-species functional response for describing predators switching between multiple prey species. Our theory includes the Holling type II functional response as a special case and makes consistent predictions when populations of equivalent prey are aggregated or split. An analysis of the derived functional response enables us to highlight the following five main findings. (1) Prey switching leads to an approximate power-law relationship between ratios of prey abundance and prey intake, consistent with experimental data. (2) In agreement with empirical observations, the theory predicts an upper limit of 2 for the exponent of such power laws. (3) Our theory predicts deviations from power-law switching at very low and very high prey-abundance ratios. (4) The theory can predict the diet composition of a predator feeding on multiple prey species from diet observations for predators feeding only on pairs of prey species. (5) Predators foraging on more prey species will show less pronounced prey switching than predators foraging on fewer prey species, thus providing a natural explanation for the known difficulties of observing prey switching in the field. (C) 2013 Elsevier Ltd. All rights reserved.

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In this article I consider the debate over whether line 1520b ought to be read as the emended “hond sweng” or the scribal “hord swenge.” It is a small point philologically but it raises interesting cultural and literary questions about the attitude of the Beowulf poet to arms and armour, to aggressive and defensive war gear, and to swords in particular. It has widely been assumed that swords are important in Beowulf and yet, the question of what their significance might be has received very little attention. Throughout the poem the hero is plagued by breaking, melting, and failing swords. He borrows, finds, and is given swords but unlike other English and Germanic heroes he is never identified with a single, great sword. I suggest that this is because, ultimately, Beowulf is conceived as a hondbana, a designation which has implications for what kind of a hero he proves to be.

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Body Area Networks are unique in that the large-scale mobility of users allows the network itself to travel across a diverse range of operating domains or even to enter new and unknown environments. This network mobility is unlike node mobility in that sensed changes in inter-network interference level may be used to identify opportunities for intelligent inter-networking, for example, by merging or splitting from other networks, thus providing an extra degree of freedom. This paper introduces the concept of context-aware bodynets for interactive environments using inter-network interference sensing. New ideas are explored at both the physical and link layers with an investigation based on a 'smart' office environment. A series of carefully controlled measurements of the mesh interconnectivity both within and between an ambulatory body area network and a stationary desk-based network were performed using 2.45 GHz nodes. Received signal strength and carrier to interference ratio time series for selected node to node links are presented. The results provide an insight into the potential interference between the mobile and static networks and highlight the possibility for automatic identification of network merging and splitting opportunities. © 2010 ACM.

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Social psychologists have attempted to capture the ideological quality of the nation through a consideration of its taken-for-granted quality, whereby it forms an unnoticed ‘banal’ background to everyday life and is passively absorbed by its members in contrast to its ‘hot’, politically created and contested nature. Accordingly, national identity is assumed to be both passively absorbed from the national backdrop and actively acquired through national inculcation. This raises the question of how national identity is expressed, transmitted and acquired in a foreign context, where the banal national backdrop is unavailable to scaffold identity and the national resources for identity transmission may be unavailable. The present article addresses this gap by examining the situation of Irish women raising children in England. Critical discursive analyses of the 16 interviews revealed that all women treated their children’s national identity and the issue of transmitting identity as dilemmatic: passive transmission risks children passively absorbing English, but active transmission contravenes the assumed naturalness of national identity and can furthermore conflict with children’s own personal choice. These results point to the complex interaction between the management of national identity and the broader personal and national context within which this occurs.

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Prader-Willi syndrome (PWS) and Fragile X syndrome (FraX) are associated with distinctive cognitive and behavioural profiles. We examined whether repetitive behaviours in the two syndromes were associated with deficits in specific executive functions. PWS, FraX, and typically developing (TD) children were assessed for executive functioning using the Test of Everyday Attention for Children and an adapted Simon spatial interference task. Relative to the TD children, children with PWS and FraX showed greater costs of attention switching on the Simon task, but after controlling for intellectual ability, these switching deficits were only significant in the PWS group. Children with PWS and FraX also showed significantly increased preference for routine and differing profiles of other specific types of repetitive behaviours. A measure of switch cost from the Simon task was positively correlated to scores on preference for routine questionnaire items and was strongly associated with scores on other items relating to a preference for predictability. It is proposed that a deficit in attention switching is a component of the endophenotypes of both PWS and FraX and is associated with specific behaviours. This proposal is discussed in the context of neurocognitive pathways between genes and behaviour.

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This paper proposes a discrete mixture model which assigns individuals, up to a probability, to either a class of random utility (RU) maximizers or a class of random regret (RR) minimizers, on the basis of their sequence of observed choices. Our proposed model advances the state of the art of RU-RR mixture models by (i) adding and simultaneously estimating a membership model which predicts the probability of belonging to a RU or RR class; (ii) adding a layer of random taste heterogeneity within each behavioural class; and (iii) deriving a welfare measure associated with the RU-RR mixture model and consistent with referendum-voting, which is the adequate mechanism of provision for such local public goods. The context of our empirical application is a stated choice experiment concerning traffic calming schemes. We find that the random parameter RU-RR mixture model not only outperforms its fixed coefficient counterpart in terms of fit-as expected-but also in terms of plausibility of membership determinants of behavioural class. In line with psychological theories of regret, we find that, compared to respondents who are familiar with the choice context (i.e. the traffic calming scheme), unfamiliar respondents are more likely to be regret minimizers than utility maximizers. © 2014 Elsevier Ltd.

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This paper examines an initiative promoting collaboration between schools located in a city setting in Northern Ireland, which is broadly divided along ethnic and political lines. The schools involved, like the vast majority of schools in Northern Ireland, educate Protestant and Catholic children separately. This presents particular challenges for school collaboration as it implies the establishment of new, connected relationships in an education system, which is historically and contemporaneously more characterised by division. Since 2007, the schools in this study have been involved in an education initiative which promotes cross-sectoral shared learning in core areas of the curriculum with a view to promoting school improvement; the additional, indirect goal is also about improving community relations. However, over this period, the relationship between the institutions has deepened, leading schools to examine how they can sustain partnership and evolve collaborative practice. This paper explores how the partnership has evolved and assesses its effectiveness as a collaborative enterprise. The paper concludes by demonstrating how effective collaboration between schools in Northern Ireland mitigates the potentially negative impacts of educating children separately, but also how effective models of school collaboration are capable of providing enhanced learning opportunities for pupils and are also capable of developing the communities in which they are located.

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In today’s world, supply chains are becoming more complex and more vulnerable due to increased interdependency of multiple threats. This paper investigates the vulnerability sources in context of sustainable supply chain in order to minimize the impact of uncertain events. The capability-based perspective is discussed in this paper to understand the strategies to improve the resilience of the supply chain. Paper argues that organisations must think beyond their boundaries to accumulate or integrate network resources and develop critical collaborative capabilities across the supply chain to successfully encounter future disruptions.