173 resultados para Voluntary Movement


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While the origins of consonance and dissonance in terms of acoustics, psychoacoustics and physiology have been debated for centuries, their plausible effects on movement synchronization have largely been ignored. The present study aims to address this by investigating whether, and if so how, consonant/dissonant pitch intervals affect the spatiotemporal properties of regular reciprocal aiming movements. We compared movements synchronized either to consonant or to dissonant sounds, and showed that they were differently influenced by the degree of consonance of the sound presented. Interestingly, the difference was present after the sound stimulus was removed. In this case, the performance measured after consonant sound exposure was found to be more stable and accurate, with a higher percentage of information/movement coupling (tau-coupling) and a higher degree of movement circularity when compared to performance measured after the exposure to dissonant sounds. We infer that the neural resonance representing consonant tones leads to finer perception/action coupling which in turn may help explain the prevailing preference for these types of tones.

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Previous research has shown that Parkinson's disease (PD) patients can increase the speed of their movement when catching a moving ball compared to when reaching for a static ball (Majsak et al., 1998). A recent model proposed by Redgrave et al. (2010) explains this phenomenon with regard to the dichotomic organization of motor loops in the basal ganglia circuitry and the role of sensory micro-circuitries in the control of goal-directed actions. According to this model, external visual information that is relevant to the required movement can induce a switch from a habitual control of movement toward an externally-paced, goal-directed form of guidance, resulting in augmented motor performance (Bienkiewicz et al., 2013). In the current study, we investigated whether continuous acoustic information generated by an object in motion can enhance motor performance in an arm reaching task in a similar way to that observed in the studies of Majsak et al. (1998, 2008). In addition, we explored whether the kinematic aspects of the movement are regulated in accordance with time to arrival information generated by the ball's motion as it reaches the catching zone. A group of 7 idiopathic PD (6 male, 1 female) patients performed a ball-catching task where the acceleration (and hence ball velocity) was manipulated by adjusting the angle of the ramp. The type of sensory information (visual and/or auditory) specifying the ball's arrival at the catching zone was also manipulated. Our results showed that patients with PD demonstrate improved motor performance when reaching for a ball in motion, compared to when stationary. We observed how PD patients can adjust their movement kinematics in accordance with the speed of a moving target, even if vision of the target is occluded and patients have to rely solely on auditory information. We demonstrate that the availability of dynamic temporal information is crucial for eliciting motor improvements in PD. Furthermore, these effects appear independent from the sensory modality through-which the information is conveyed. 

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To intercept a moving object, one needs to be in the right place at the right time. In order to do this, it is necessary to pick up and use perceptual information that specifies the time to arrival of an object at an interception point. In the present study, we examined the ability to intercept a laterally moving virtual sound object by controlling the displacement of a sliding handle and tested whether and how the interaural time difference (ITD) could be the main source of perceptual information for successfully intercepting the virtual object. The results revealed that in order to accomplish the task, one might need to vary the duration of the movement, control the hand velocity and time to reach the peak velocity (speed coupling), while the adjustment of movement initiation did not facilitate performance. Furthermore, the overall performance was more successful when subjects employed a time-to-contact (tau) coupling strategy. This result shows that prospective information is available in sound for guiding goal-directed actions.

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The Emerging Church Movement (ECM) is a primarily Western religious phenomenon, identifiable by its critical ‘deconstruction’ of ‘modern’ religion. While most prominent in North America, especially the United States, some of the most significant contributors to the ECM ‘conversation’ have been the Belfast-based Ikon Collective and one of its founders, philosopher Peter Rollins. Their rootedness in the unique religious, political and social landscape of Northern Ireland in part explains their position on the ‘margins’ of the ECM, and provides many of the resources for their contributions. Ikon’s development of ‘transformance art’ and its ‘leaderless’ structure raise questions about the institutional viability of the wider ECM. Rollins’ ‘Pyrotheology’ project, grounded in his reading of post-modern philosophy, introduces more radical ideas to the ECM conversation. Northern Ireland’s ‘Troubles’ and ‘marginal’ location provides the ground from which Rollins and Ikon have been able to expose the boundaries of the ECM and raise questions about just how far the ECM may go in its efforts to transform Western Christianity.

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Nearly 4000 people died in Northern Ireland’s long running conflict, 314 of them police officers (Brewer and Magee 1991, Brewer 1996, Hennessey 1999, Guelke and Milton-Edwards 2000). The republican and loyalist ceasefires of 1994 were the first significant signal that NI society was moving beyond the ‘troubles’ and towards a normalised political environment. The Belfast (Good Friday) Agreement of 1998 cemented that movement (Hennessey 1999). Policing was a key and seemingly unresolvable element of the conflict, seen as unrepresentative and partisan. Its reform or ‘recasting’ in a new dispensation was an integral part of the conflict transformation endeavour(Ellison 2010). As one of the most controversial elements of the conflicted past, it had remained outside the Agreement and was subject to a specific commission of interest (1999), generally known as the Patten Commission. The Commission’s far reaching proposals included a change of name, badge and uniform, the introduction of 50/50 recruitment (50% Roman Catholic and 50% other), a new focus on human rights, a new district command and headquarter structure, a review of ‘Special Branch’ and covert techniques, a concern for ‘policing with the community’ and a significant voluntary severance process to make room for new recruits, unconnected with the past history of the organisation(Murphy 2013).

This paper reflects upon the first data collection phase of a long term processual study of organisational change within the Royal Ulster Constabulary / Police Service of Northern Ireland. This phase (1996-2002) covers early organisational change initiation (including the pre-change period) and implementation including the instigation of symbolic changes (name, badge, and crest) and structural changes (new HQ structure and District Command structure). It utilises internal documentation including messages from the organisations leaders, interviews with forty key informants (identified through a combination of snow-balling from referrals by initial contacts, and key interviews with significant individuals), as well as external documentation and commentary on public perceptions of the change. Using a processual lens (Langley, Smallman et al. 2013) it seeks to understand this initial change phase and its relative success in a highly politicised environment.

By engaging key individuals internally and externally, setting up a dedicated change team, adopting a non normative, non urgent, calming approach to dissent, communicating in orthodox and unorthodox ways with members, acknowledging the huge emotional strain of letting go of the organisation’s name and all it embodied, and re-emphasising the role of officers as ‘police first’, rather than ‘RUC first’, the organisations leadership remained in control of a volatile and unhappy organisational body and succeeded in moving it on through this initial phase, even while much of the political establishment lambasted them externally. Three years into this change process the organisation had a new name, a new crest, new structures, procedures and was deeply engaged in embedding the joint principles of human rights and community policing within its re-woven fabric. While significant problems remained, the new Police Service of Northern Ireland had successfully begun a long journey to full community acceptance in a post conflict context.

This case illustrates the significant challenges of leading change under political pressure, with external oversight and no space for failure(Hannah, Uhl-Bien et al. 2009). It empirically reflects the reality of change implementation as messy, disruptive and unpredictable and highlights the significance of political skill and contextual understanding to success in the early stages(Buchanan and Boddy 1992). The implications of this for change theory and the practice of change implementation are explored (Eisenhardt and Graebner 2007) and some conclusions drawn about what such an extreme case tells us about change generally and change implementation under pressure.

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In this research, an agent-based model (ABM) was developed to generate human movement routes between homes and water resources in a rural setting, given commonly available geospatial datasets on population distribution, land cover and landscape resources. ABMs are an object-oriented computational approach to modelling a system, focusing on the interactions of autonomous agents, and aiming to assess the impact of these agents and their interactions on the system as a whole. An A* pathfinding algorithm was implemented to produce walking routes, given data on the terrain in the area. A* is an extension of Dijkstra's algorithm with an enhanced time performance through the use of heuristics. In this example, it was possible to impute daily activity movement patterns to the water resource for all villages in a 75 km long study transect across the Luangwa Valley, Zambia, and the simulated human movements were statistically similar to empirical observations on travel times to the water resource (Chi-squared, 95% confidence interval). This indicates that it is possible to produce realistic data regarding human movements without costly measurement as is commonly achieved, for example, through GPS, or retrospective or real-time diaries. The approach is transferable between different geographical locations, and the product can be useful in providing an insight into human movement patterns, and therefore has use in many human exposure-related applications, specifically epidemiological research in rural areas, where spatial heterogeneity in the disease landscape, and space-time proximity of individuals, can play a crucial role in disease spread.