3,320 research outputs found

    Desperate Prawns: Drivers of Behavioural Innovation Vary across Social Contexts in Rock Pool Crustaceans

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    Innovative behaviour may allow animals to cope with changes in their environment. Innovative propensities are known to vary widely both between and within species, and a growing body of research has begun to examine the factors that drive individuals to innovate. Evidence suggests that individuals are commonly driven to innovate by necessity; for instance by hunger or because they are physically unable to outcompete others for access to resources. However, it is not known whether the factors that drive individuals to innovate are stable across contexts. We examined contextual variation in the drivers of innovation in rock pool prawns (Palaemon spp), invertebrates that face widely fluctuating environments and may, through the actions of tides and waves, find themselves isolated or in groups. Using two novel foraging tasks, we examined the effects of body size and hunger in prawns tested in solitary and group contexts. When tested alone, small prawns were significantly more likely to succeed in a spatial task, and faster to reach the food in a manipulation task, while hunger state had no effect. In contrast, size had no effect when prawns were tested in groups, but food-deprived individuals were disproportionately likely to innovate in both tasks. We suggest that contextual variation in the drivers of innovation is likely to be common in animals living in variable environments, and may best be understood by considering variation in the perception of relative risks and rewards under different conditions.Biotechnology and Biological Sciences Research Council (BBSRC) - David Phillips Fellowshi

    No effect of arm exercise on diaphragmatic fatigue or ventilatory constraint in Paralympic athletes with cervical spinal cord injury

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    Cervical spinal cord injury (CSCI) results in a decrease in the capacity of the lungs and chest wall for pressure, volume, and airflow generation. We asked whether such impairments might increase the potential for exercise-induced diaphragmatic fatigue and mechanical ventilatory constraint in this population. Seven Paralympic wheelchair rugby players (mean ± SD peak oxygen uptake = 16.9 ± 4.9 ml·kg–1·min–1) with traumatic CSCI (C5–C7) performed arm-crank exercise to the limit of tolerance at 90% of their predetermined peak work rate. Diaphragm function was assessed before and 15 and 30 min after exercise by measuring the twitch transdiaphragmatic pressure (Pdi,tw) response to bilateral anterolateral magnetic stimulation of the phrenic nerves. Ventilatory constraint was assessed by measuring the tidal flow volume responses to exercise in relation to the maximal flow volume envelope. Pdi,tw was not different from baseline at any time after exercise (unpotentiated Pdi,tw = 19.3 ± 5.6 cmH2O at baseline, 19.8 ± 5.0 cmH2O at 15 min after exercise, and 19.4 ± 5.7 cmH2O at 30 min after exercise; P = 0.16). During exercise, there was a sudden, sustained rise in operating lung volumes and an eightfold increase in the work of breathing. However, only two subjects showed expiratory flow limitation, and there was substantial capacity to increase both flow and volume (<50% of maximal breathing reserve). In conclusion, highly trained athletes with CSCI do not develop exercise-induced diaphragmatic fatigue and rarely reach mechanical ventilatory constraint

    Cancer patient experience measures: An evidence review

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    © 2016 Taylor & Francis Group, LLC. Objectives: This research investigates the instruments currently available to measure the cancer patient experience of health care. An investigation of the number of instruments, the domains covered by the instruments, and the structure and psychometric performance of instruments is undertaken. Methods: A narrative synthesis approach is used to gather evidence from multiple studies and explain the findings. Purposely broad search terms and strategies are used to capture studies with cancer patients at all stages of disease and across a range of cancer types and health care settings. Results: The majority of identified instruments were originally designed for the oncology field. Twelve of the studies developed new cancer patient measures; eight studies adapted existing or utilized items from existing instruments, and seven studies assessed the psychometric properties of existing instruments or assessed validated tools under different conditions (e.g., cross-cultural adaptation). The number of instruments assessing cancer patient experience that have sound psychometric properties across items was found to be low. The properties least tested are test–retest reliability, construct, convergent and discriminant validity, scale variability (floor/ceiling effects), and interpretability. Conclusion: This review examined 10 years of research on the development of instruments to measure the cancer patient experience of health care. It found that research in this area is still in early stages of development. Further inquiry based on development and validation of cancer patient experience measures is required to support improvements in cancer care based on the perspective of cancer patients

    Large deviations for clocks of self-similar processes

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    The Lamperti correspondence gives a prominent role to two random time changes: the exponential functional of a L\'evy process drifting to \infty and its inverse, the clock of the corresponding positive self-similar process. We describe here asymptotical properties of these clocks in large time, extending the results of Yor and Zani

    Avatars of Eurocentrism in the critique of the liberal peace

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    Recent scholarly critiques of the so-called liberal peace raise important political and ethical challenges to practices of postwar intervention in the global South. However, their conceptual and analytic approaches have tended to reproduce rather than challenge the intellectual Eurocentrism underpinning the liberal peace. Eurocentric features of the critiques include the methodological bypassing of target subjects in research, the analytic bypassing of subjects through frameworks of governmentality, the assumed ontological split between the ‘liberal’ and the ‘local’, and a nostalgia for the liberal subject and the liberal social contract as alternative bases for politics. These collectively produce a ‘paradox of liberalism’ that sees the liberal peace as oppressive but also the only true source of emancipation. However, the article suggests that a repoliticization of colonial difference offers an alternative ‘decolonizing’ approach to critical analysis through repositioning the analytic gaze. Three alternative research strategies for critical analysis are briefly developed

    Computable bounds in fork-join queueing systems

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    In a Fork-Join (FJ) queueing system an upstream fork station splits incoming jobs into N tasks to be further processed by N parallel servers, each with its own queue; the response time of one job is determined, at a downstream join station, by the maximum of the corresponding tasks' response times. This queueing system is useful to the modelling of multi-service systems subject to synchronization constraints, such as MapReduce clusters or multipath routing. Despite their apparent simplicity, FJ systems are hard to analyze. This paper provides the first computable stochastic bounds on the waiting and response time distributions in FJ systems. We consider four practical scenarios by combining 1a) renewal and 1b) non-renewal arrivals, and 2a) non-blocking and 2b) blocking servers. In the case of non blocking servers we prove that delays scale as O(logN), a law which is known for first moments under renewal input only. In the case of blocking servers, we prove that the same factor of log N dictates the stability region of the system. Simulation results indicate that our bounds are tight, especially at high utilizations, in all four scenarios. A remarkable insight gained from our results is that, at moderate to high utilizations, multipath routing 'makes sense' from a queueing perspective for two paths only, i.e., response times drop the most when N = 2; the technical explanation is that the resequencing (delay) price starts to quickly dominate the tempting gain due to multipath transmissions

    Quantum spin systems at positive temperature

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    We develop a novel approach to phase transitions in quantum spin models based on a relation to their classical counterparts. Explicitly, we show that whenever chessboard estimates can be used to prove a phase transition in the classical model, the corresponding quantum model will have a similar phase transition, provided the inverse temperature β\beta and the magnitude of the quantum spins \CalS satisfy \beta\ll\sqrt\CalS. From the quantum system we require that it is reflection positive and that it has a meaningful classical limit; the core technical estimate may be described as an extension of the Berezin-Lieb inequalities down to the level of matrix elements. The general theory is applied to prove phase transitions in various quantum spin systems with \CalS\gg1. The most notable examples are the quantum orbital-compass model on Z2\Z^2 and the quantum 120-degree model on Z3\Z^3 which are shown to exhibit symmetry breaking at low-temperatures despite the infinite degeneracy of their (classical) ground state.Comment: 47 pages, version to appear in CMP (style files included

    Desperately constructing ethnic audiences: Anti-immigration discourses and minority audience research in the Netherlands

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    This article examines how minority ethnic audiences are measured, and thus constructed, in the Netherlands today. The analysis shows that this process is tightly woven into the dominant assimilationist and neoliberal discourse. This discourse portrays specific minority groups as deviant in relation to an essentialized notion of Dutchness. Furthermore, it presents social inclusion as an opportunity that is limited to well-adjusted, profitable consumers. Different attempts to represent minority audiences – including efforts to promote a more just minority representation in Dutch media – are compelled to accommodate to this dominant discourse. The article underscores the limited scope for contesting current hegemonic representations of minority groups and national belonging in the Netherlands

    Power and the durability of poverty: a critical exploration of the links between culture, marginality and chronic poverty

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    Population policies and education: exploring the contradictions of neo-liberal globalisation

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    The world is increasingly characterised by profound income, health and social inequalities (Appadurai, 2000). In recent decades development initiatives aimed at reducing these inequalities have been situated in a context of increasing globalisation with a dominant neo-liberal economic orthodoxy. This paper argues that neo-liberal globalisation contains inherent contradictions regarding choice and uniformity. This is illustrated in this paper through an exploration of the impact of neo-liberal globalisation on population policies and programmes. The dominant neo-liberal economic ideology that has influenced development over the last few decades has often led to alternative global visions being overlooked. Many current population and development debates are characterised by polarised arguments with strongly opposing aims and views. This raises the challenge of finding alternatives situated in more middle ground that both identify and promote the socially positive elements of neo-liberalism and state intervention, but also to limit their worst excesses within the population field and more broadly. This paper concludes with a discussion outling the positive nature of middle ground and other possible alternatives
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