931 resultados para Fighting asymmetry
Resumo:
Energetic costs of fighting, such as high lactate or low glucose, have been shown in a range of species to correlate with the decisions made by each opponent, particularly the decision by one opponent, the 'loser', to end the fight by 'giving up'. Studies based on complete fights of differing duration, however, do not provide information on the changes in the physiological correlates of fighting that may take place during the course of the encounter, or how these changes may influence the capability and decisions of the contestants. We interrupted fights between hermit crabs, Pagurus bernhardus, at specific points, and related energy status to the preceding activities. Costs rose quickly with a rapid accumulation of lactic acid in attackers and declining muscular glycogen in defenders. Changes in physiological status appeared much earlier than the changes in behaviour that they may have caused. Furthermore, some physiological changes might have been an effect, rather than the cause, of fight decisions. (c) 2005 The Association for the Study of Animal Behaviour Published by Elsevier Ltd. All rights reserved.
Resumo:
Selection should favour accurate information gathering regarding the likely costs and benefits of continued conflict. Here we consider how variation in the abilities of contestants to assess resource-holding potential (RHP) influences fights. This has been examined in various game theory models. However, discriminating between assessment strategies has proven difficult and has resulted in confusion. To add clarity, we group existing models into three main types that differ in the information about RHP that contestants are presumed to gather: (1) pure self-assessment, (2) cumulative assessment and (3) mutual assessment. Within this framework we outline methods advocated to discriminate successfully between the three main assessment models. We discuss support for each model, before highlighting a number of conflicting and inconclusive studies, leading us to consider alternative approaches to investigate assessment. Furthermore, we examine support for newly emerging concepts such as 'varying degrees of assessment', 'switching assessment' strategies and the possibility of contestants adopting different assessment strategies within a fight involving distinctive roles. We suggest future studies will benefit by judicious use of a battery of techniques to determine how animals settle contests. Finally, we highlight difficulties with current game theory models, and raise concerns regarding the use of certain behavioural criteria to accept or reject a model, particularly since this may conflict with evidence for a given assessment strategy. Furthermore, the failure of existing models to account for newly emerging concepts points to limitations of their use and leads us to challenge game theoreticians to develop upon them. (C) 2009 The Association for the Study of Animal Behaviour. Published by Elsevier Ltd. All rights reserved.
Resumo:
Background: Keratoconus, a non-inflammatory corneal ectasia, is reported to have bilateral involvement in over 90% of patients. The purpose of this study was to quantify the extent of asymmetry of disease at presentation to a regional corneal clinic.
Resumo:
This paper is part of a larger project in which the author is interested in recovering popular performative traditions and practices that have been occluded by the modernist project of the Irish Revival. This erasure has been compounded by subsequent historiographical paradigms that have reinforced the revivalist narrative of theatre history and excluded indigenous forms, traditions and practices (mumming, rhymers, strawboys) along with the wider performative culture of patterns, wakes, fairs, faction fights etc. This essay subjects to scrutiny what the author sees as a disjuncture between the riotous reality of peasant popular culture and its representation in Revivalist dramas to argue that Irish Theatre Studies needs to develop alternative historiographies of performance and to methodologically engage with theoretical models extant in Performance Studies.
Resumo:
The precise rationale for, and timing of, the Northern Ireland peace process of the 1990s and beyond, which developed after more than two decades of conflict, has yet to be fully explained. It has been a common assumption that it arose from a stalemate involving the Irish Republican Army (IRA), the 'regular' pro-state forces of the British Army and Royal Ulster Constabulary and the 'irregular/ultra' pro-state loyalist paramilitary groups of the Ulster Volunteer Force (UVF) and Ulster Defence Association (UDA). Under this interpretation, military/paramilitary deadlock led to ripeness for peace, amid reappraisals by all parties to the conflict of the utility of violence accompanied by reinterpretations of earlier political orthodoxies. The IRA could not remove the British sovereign claim to Northern Ireland; British forces could not militarily defeat the IRA and loyalists and republicans were engaged in a futile inter-communal sectarian war. This stalemate thesis has obvious attraction in explaining why a seemingly intractable war finally subsided, but is less convincing when subject to empirical testing among republican and loyalist participants in the conflict. This article moves away from 'top-down' generalist narratives of the onset of peace, which tend to argue the stalemate thesis, to assess 'bottom-up' interpretations from the actual combatants as to why they ceased fighting. It suggests an asymmetry, rather than mutuality, of perception that there was 'military' cessation by the armed non-state groups, with neither republican nor loyalist interpretations grounded in notions of stalemate. The article concludes by urging a wider consideration of the important and persistent interplay of the military and political in conflicts such as Northern Ireland.
Resumo:
We present mid-infrared (5.2-15.2 mu m) spectra of the Type Ia supernovae (SNe Ia) 2003hv and 2005df observed with the Spitzer Space Telescope. These are the first observed mid-infrared spectra of thermonuclear supernovae, and show strong emission from fine-structure lines of Ni, Co, S, and Ar. The detection of Ni emission in SN 2005df 135 days after the explosion provides direct observational evidence of high-density nuclear burning forming a significant amount of stable Ni in a SN Ia. The SN 2005df Ar lines also exhibit a two-pronged emission profile, implying that the Ar emission deviates significantly from spherical symmetry. The spectrum of SN 2003hv also shows signs of asymmetry, exhibiting blueshifted [Co (III)], which matches the blueshift of [Fe (II)] lines in nearly coeval near-infrared spectra. Finally, local thermodynamic equilibrium abundance estimates for the yield of radioactive Ni-56 give M-56Ni approximate to 0.5 M-circle dot, for SN 2003hv, but only M-56Ni approximate to 0.13-0.22 M-circle dot for the apparently subluminous SN 2005df, supporting the notion that the luminosity of SNe Ia is primarily a function of the radioactive 56Ni yield. The observed emission-line profiles in the SN 2005df spectrum indicate a chemically stratified ejecta structure, which matches the predictions of delayed detonation (DD) models, but is entirely incompatible with current three-dimensional deflagration models. Furthermore, the degree that this layering persists to the innermost regions of the supernova is difficult to explain even in a DD scenario, where the innermost ejecta are still the product of deflagration burning. Thus, while these results are roughly consistent with a delayed detonation, it is clear that a key piece of physics is still missing from our understanding of the earliest phases of SN Ia explosions.