65 resultados para Top-down control

em Deakin Research Online - Australia


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Background/ Aim: Therapists use different types of tests, scales, and instruments to assess children's motor skills, including those classified as being top-down and bottom-up. The aim of the study was to investigate the ability of measures of children's motor skill performance from the perspectives of children and parents (a type of top-down assessment) to predict children's performance-based motor ability test results (a type of bottom-up assessment).
Methods: A convenience sample of 38 children and parents was recruited from Victoria, Australia. Motor skill performance was evaluated from a top-down perspective using the Physical Self-Description Questionnaire (PSDQ) and the Movement Assessment Battery for Children – Second Edition (MABC-2) Checklist to measure children's and parents' perspectives respectively. Motor skill performance was also evaluated from a bottom-up approach using the Bruininks-Oseretsky Test of Motor Proficiency – Second Edition (BOT-2). Data were analyzed using multiple linear regression analysis to determine whether the PSDQ or MABC-2 Checklist was predictive of the children's BOT-2 performance results.
Results: Two predictive relationships were identified based on parents' perspectives, where the total score of the MABC-2 Checklist was found to be a significant predictor of the BOT-2 Manual Coordination motor composite score, accounting for 8.35% of its variance, and the BOT-2 Strength and Agility motor composite score, accounting for 11.6% of its variance. No predictive relationships were identified between the children's self-report PSDQ perspectives and the BOT-2 performance scores.
Conclusions: Therapists are encouraged to utilize a combination of top-down and bottom-up approaches and purposefully to seek parents' and children's perspectives when evaluating children's motor skill performance.

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Disentangling the effects of prey limitation (bottom-up) and predation (top-down) processes on natural populations is difficult, but the perturbations introduced by an invasive species can provide pseudo-experimental evidence on this issue.

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Long-term changes in mesozooplankton and phytoplankton populations have been well documented in the North Atlantic region, whereas data for microzooplankton are scarce. This neglected component of the plankton is a vital link in marine food-webs, grazing on smaller flagellates and cyanobacteria and in turn providing food for the larger mesozooplankton. We use the latest tintinnid (Ciliophora, Protista) data from the Continuous Plankton Recorder (CPR) survey in the NE Atlantic and North Sea to examine the phenology, distribution and abundance of this important group of ciliates. Presence/absence data came from 167 122 CPR samples collected between 1960 and 2009 and abundance data from 49 662 samples collected between 1996 and 2009. In the North Atlantic the genus Dictyocysta spp. dominated and Parafavella gigantea showed an increase in abundance around Iceland and Greenland. In the North Sea higher densities of Tintinnopsis spp., Favella serrata and Ptychocylis spp. were found. The presence of tintinnids in CPR samples collected in the North Atlantic has increased over the last 50 years and the seasonal window of high abundance has lengthened. Conversely in the North Sea there has been an overall reduction in abundance. We discuss possible drivers for these long-term changes and point the way forward to more holistic studies that examine how ecosystems, rather than just selected taxa, are responding to climate change.

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Considerable uncertainties often surround the causes of long-term changes in population abundance. One striking example is the precipitous decline of southern sea lions (SSL; Otariaflavescens) at the Falkland Islands, from 80 555 pups in the mid 1930s to just 5506 pups in 1965. Despite an increase in SSL abundance over the past two decades, the population has not recovered, with the number of pups born in 2014 (minimum 4443 pups) less than 6% of the 1930s estimate. The order-of-magnitude decline is primarily attributed to commercial sealing in Argentina. Here, we test this established paradigm and alternative hypotheses by assessing (1) commercial sealing at the Falkland Islands, (2) winter migration of SSL from the Falkland Islands to Argentina, (3) whether the number of SSL in Argentina could have sustained the reported level of exploitation, and (4) environmental change. The most parsimonious hypothesis explaining the SSL population decline was environmental change. Specifically, analysis of 160 years of winter sea surface temperatures revealed marked changes, including a period of warming between 1930 and 1950 that was consistent with the period of SSL decline. Sea surface temperature changes likely influenced the distribution or availability of SSL prey and impacted its population dynamics. We suggest that historical harvesting may not always be the "smoking gun" as is often purported. Rather, our conclusions support the growing evidence for bottom-up forcing on the abundance of species at lower trophic levels (e.g., plankton and fish) and resulting impacts on higher trophic levels across a broad range of ecosystems.

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Over the last m'o decades, university systems world-wide have been subject to government initiated, top-down restructures in the name of greater effectiveness, accountability and quality. Within this timefrome, government interest in university teaching has increased, and innovation and responsiveness in teaching have been increasingly prioritised by both government and university policies. AcademiC interest in the teaching has also increased. and much research and discussion has focused on defining teaching as a source of scholarship and expounding its role in the promotion of innovation, and in the recognition and rewarding of teaching work. In this paper, I draw on a study of academics' views, which I have reported at previous AARE conferences and elsewhere, to raise questions about recent and ongoing developments in the work environment of university educators.l raise the possibility that systems and processes whose express purpose is to facilitate and support university educators' efforts to improve teaching are, in fact. inhibiting innovative practice by institutionalising an aversion to risk that is anathema to innovation.

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1. Apex predators can benefit ecosystems through top–down control of mesopredators and herbivores. However, apex predators are often subject to lethal control aimed at minimizing attacks on livestock. Lethal control can affect both the abundance and behaviour of apex predators. These changes could in turn influence the abundance and behaviour of mesopredators.

2. We used remote camera surveys at nine pairs of large Australian rangeland properties, comparing properties that controlled dingoes Canis lupus dingo with properties that did not, to test the effects of predator control on dingo activity and to evaluate the responses of a mesopredator, the feral cat Felis catus.

3. Indices of dingo abundance were generally reduced on properties that practiced dingo control, in comparison with paired properties that did not, although the effect size of control was variable. Dingoes in uncontrolled populations were crepuscular, similar to major prey. In populations subject to control, dingoes became less active around dusk, and activity was concentrated in the period shortly before dawn.

4. Shifts in feral cat abundance indices between properties with and without dingo control were inversely related to corresponding shifts in indices of dingo abundance. There was also a negative relationship between predator visitation rates at individual camera stations, suggesting cats avoided areas where dingoes were locally common. Reduced activity by dingoes at dusk was associated with higher activity of cats at dusk.

5. Our results suggest that effective dingo control not only leads to higher abundance of feral cats, but allows them to optimize hunting behaviour when dingoes are less active. This double effect could amplify the impacts of dingo control on prey species selected by cats. In areas managed for conservation, stable dingo populations may thus contribute to management objectives by restricting feral cat access to prey populations.

6. Synthesis and applications. Predator control not only reduces indices of apex predator abundance but can also modify their behaviour. Hence, indicators other than abundance, such as behavioural patterns, should be considered when estimating a predator's capacity to effectively interact with lower trophic guilds. Changes to apex predator behaviour may relax limitations on the behaviour of mesopredators, providing enhanced access to resources and prey.

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Research on the ecology of top predators - upper trophic level consumers that are relatively free from predation once they reach adult size - has provided regular contributions to general ecology and is a rapidly expanding and increasingly experimental, multidisciplinary and technological endeavour. Yet, an exponentially expanding literature coupled with rapid disintegration into specialized, disconnected subfields for study (e.g. vertebrate predators versus invertebrate predators, community ecology versus biological control etc.) increasingly means that we are losing a coherent, integrated understating of the role and importance of these species in ecosystems. This process of canalization is likely to hinder sharing of scientific discovery and continued progress, especially as there is a growing need to understand the generality of the top-down forcing, as demonstrated for some members of this group. Here, we propose ways to facilitate synthesis by promoting changes in mentality and awareness among specialists through increased debate and collaboration, conceptual reviews and a series of exemplary case studies. The strategy will rely on the collective contribution by all scientists in the field and will strive to consolidate and formalise top-order predation as a holistic, cohesive, cross-taxonomical field of research studying the ecology, evolution and behaviour of apex predators and their capability to exert top-down forcing on lower trophic levels. © 2014 The Authors.

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Purpose – The purpose of this paper is to demonstrate how leadership has the capacity to both positively influence learning processes and negatively inhibit organizational learning.

Design/methodology/approach – This is a conceptual paper that brings together an analysis of leadership and organizational learning literature. The argument is centered on transformational leadership and the responsibility for creating an organizational learning culture.

Findings – There is a conventional belief that leaders have solitary control and influence when it comes to setting up organizational learning processes. However, a top-down approach to facilitate and implement learning in organizations is not always an effective method because learning should be a collaborative practice. Thus, to rely fully on leaders to initiate and sustain the learning processes can be counter-productive.

Practical implications – Good and effective leadership is the key to organizational learning. Learning is the only sustainable method of achieving competitive advantage for contemporary organizations because of rapidly changing environmental forces. Corporations with aspirations for long-term survival must facilitate, through their leadership, “the impulse to learn” amongst their members.

Originality/value – Knowledge is lacking in the area where leadership is linked to learning. Such knowledge is important because leaders play a central role in the learning framework and leaders also offer the required guidance for organizations to integrate and sustain learning processes through policy and practice.

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In 1997, the New Labour government inherited a ‘crisis’ in the UK National Health Service from the outgoing Conservative government. To address this perceived crisis, New Labour offered investment and, contrary to expectations, further neo-liberal health service reforms. In particular, the government extended the scope of performance management beyond financial numbers to encompass all aspects of managerial and organisational performance. Drawing on an analytics of government framework, this paper demonstrates how reforms were framed and given meaning through a framework of hierarchical accountability and centralised control. These panoptical arrangements relied on performance-management technologies of targets and ratings, which were linked to patient choice and a prospective funding system called ‘Payment by Results’. In turn, these top-down technologies disciplined knowledge, identity, and visibility and control of practice.

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In many network applications, the nature of traffic is of burst type. Often, the transient response of network to such traffics is the result of a series of interdependant events whose occurrence prediction is not a trivial task. The previous efforts in IEEE 802.15.4 networks often followed top-down approaches to model those sequences of events, i.e., through making top-view models of the whole network, they tried to track the transient response of network to burst packet arrivals. The problem with such approaches was that they were unable to give station-level views of network response and were usually complex. In this paper, we propose a non-stationary analytical model for the IEEE 802.15.4 slotted CSMA/CA medium access control (MAC) protocol under burst traffic arrival assumption and without the optional acknowledgements. We develop a station-level stochastic time-domain method from which the network-level metrics are extracted. Our bottom-up approach makes finding station-level details such as delay, collision and failure distributions possible. Moreover, network-level metrics like the average packet loss or transmission success rate can be extracted from the model. Compared to the previous models, our model is proven to be of lower memory and computational complexity order and also supports contention window sizes of greater than one. We have carried out extensive and comparative simulations to show the high accuracy of our model.

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This study examined the impact of hospital restructuring moves on a sample of Australian nurses' health. The role of organizational support, assessed via levels of consultation with staff, social support, and nurses coping were examined as further contributors or mediators of the relationship between the impact of restructuring and nurses' health. Data from 201 hospital nurses indicated that the factors in the model explained 41% of the variance in nurses' health. “Top-down” communication style by management contributed negatively to nurses' health and increased their perceptions of the impact of restructuring. Support from peers, supervisors, and family together with seeing the demands of impact of restructuring as a challenge, contributed positively to nurses' health and reduced the level of avoidance strategies used. The implications of these findings are discussed.