250 resultados para Forces musculaires
Resumo:
Fatigue of the steel in rails continues to be of major concern to heavy haul track owners despite careful selection and maintenance of rails. The persistence of fatigue is due in part to the erroneous assumption that the maximum loads on, and stresses in, the rails are predictable. Recent analysis of extensive wheel impact detector data from a number of heavy haul tracks has shown that the most damaging forces are in fact randomly distributed with time and location and can be much greater than generally expected. Large- scale Monte-Carlo simulations have been used to identify rail stresses caused by actual, measured distributions of wheel-rail forces on heavy haul tracks. The simulations show that fatigue failure of the rail foot can occur in situations which would be overlooked by traditional analyses. The most serious of these situations are those where track is accessed by multiple operators and in situations where there is a mix of heavy haul, general freight and/or passenger traffic. The least serious are those where the track is carrying single-operator-owned heavy haul unit trains. The paper shows how using the nominal maximum axle load of passing traffic, which is the key issue in traditional analyses, is insufficient and must be augmented with consideration of important operational factors. Ignoring such factors can be costly.
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This paper presents research which examined perceptions on the future of work in Queensland. It highlights the major drivers of change including: changing technology, demographics, increasing globalisation and economic shifts. Focus groups were conducted and findings show that Queensland businesses are acutely aware of the coming changes, but are less certain about how to respond. Current good practices plus recommendations for the future - particularly the lead role government and industry bodies need to play - are discussed. These recommendations will support Queensland businesses to thrive and adapt to the forces shaping work in this changing regional economy.
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Overview: - The sharing economy unlocks a previously unused value of goods and labour, and causes disruption in established industries. - The pattern of disruption is similar regardless of the industry that's impacted. While the initial phases of disruption are transformational for many (e.g. lost jobs), often the industries end up stronger than before they were before the disruption. - Due to different in setting, upholding and enforcing standards, it is hard to assess the regulatory trade-offs. Safety, labour relations and social fairness are important factors to consider across the industry.
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The following paper considers the question, where to office property? In doing so, it focuses, in the first instance, on identifying and describing a selection of key forces for change present within the contemporary operating environment in which office property functions. Given the increasingly complex, dynamic and multi-faceted character of this environment, the paper seeks to identify only the primary forces for change, within the context of the future of office property. These core drivers of change have, for the purposes of this discussion, been characterised as including a range of economic, demographic and socio-cultural factors, together with developments in information and communication technology. Having established this foundation, the paper proceeds to consider the manner in which these forces may, in the future, be manifested within the office property market. Comment is offered regarding the potential future implications of these forces for change together with their likely influence on the nature and management of the physical asset itself. Whilst no explicit time horizon has been envisioned in the preparation of this paper particular attention has been accorded short to medium term trends, that is, those likely to emerge in the office property marketplace over the coming two decades. Further, the paper considers the question posed, in respect of the future of office property, in the context of developed western nations. The degree of commonality seen in these mature markets is such that generalisations may more appropriately and robustly be applied. Whilst some of the comments offered with respect to the target market may find application in other arenas, it is beyond the scope of this paper to explicitly consider highly heterogeneous markets. Given also the wide scope of this paper key drivers for change and their likely implications for the commercial office property market are identified at a global level (within the above established parameters). Accordingly, the focus is necessarily such that it serves to reflect overarching directions at a universal level (with the effect being that direct applicability to individual markets - when viewed in isolation on a geographic or property type specific basis – may not be fitting in all instances)
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Fusionless scoliosis surgery is an emerging treatment for idiopathic scoliosis as it offers theoretical advantages over current forms of treatment. Anterior vertebral stapling using a nitinol staple is one such treatment. Despite increasing interest in this technique, little is known about the effects on the spine following insertion, or the mechanism of action of the staple. The aims of this study were threefold; (1) to measure changes in the bending stiffness of a single motion segment following staple insertion, (2) to describe the forces that occur within the staple during spinal movement, and (3) to describe the anatomical changes that occur following staple insertion. Results suggest that staple insertion consistently decreased stiffness in all directions of motion. An explanation for the finding may be found in the outcomes of the strain gauge testing and micro-CT scan. The strain gauge testing showed that once inserted, the staple tips applied a baseline compressive force to the surrounding trabecular bone and vertebral end-plate. This finding would be consistent with the current belief that the clinical effect of the staples is via unilateral compression of the physis. Interestingly however, as each specimen progressed through the five cycles of each test, the baseline load on the staple tips gradually decreased, implying that the force at the staple tip-bone interface was decreasing. We believe that this was likely occurring as a result of structural damage to the trabecular bone and vertebral end-plate by the staple effectively causing ‘loosening’ of the staple. This hypothesis is further supported by the findings of the micro-CT scan. The pictures depict significant trabecular bone and physeal injury around the staple blades. These results suggest that the current hypothesis that stapling modulates growth through physeal compression may be incorrect, but rather the effect occurs through mechanical disruption of the vertebral growth plate.
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There are two aspects to the problem of digital scholarship and pedagogy. One is to do with scholarship; the other with pedagogy. In scholarship, the association of knowledge with its printed form remains dominant. In pedagogy, the desire to abandon print for ‘new’ media is urgent, at least in some parts of the academy. Film and media studies are thus at the intersection of opposing forces – pulling the field ‘back’ to print and ‘forward’ to digital media. These tensions may be especially painful in a field whose own object of study is another form of communication, neither print nor digital but broadcast. Although print has been overtaken in the popular marketplace by audio-visual forms, this was never achieved in the domain of scholarship. Even when it is digitally distributed, the output of research is still a ‘paper.’ But meanwhile, in the realm of teaching, production- and practice-based pedagogy has become firmly established. Nevertheless a disjunction remains, between high-end scholarship in research universities and vocational training in teaching institutions; but neither is well equipped to deal with the digital challenge.
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Extreme sports have unfortunately gained a reputation for being risk focused and adrenaline fuelled. This perspective has obscured the place of the natural world, making extreme athletes appear to seek to conquer, compete against or defeat natural forces. In contrast, this paper explores findings from a larger hermeneutic phenomenological study that suggests extreme sports can initiate a positive change in participants’ relationships with the natural world. Data sources include first-hand accounts of extreme sports participants such as biographies, videos, papers and journals as well as interviews with ten male and five female extreme sports participants. Reports indicate that extreme sport participants develop feelings of connection to the natural world and describe themselves as being at one with the natural world or connected through a life enhancing energy. The paper draws on theoretical perspectives in ecopsychology which suggest that feeling connected to nature leads to a desire to care for the natural world and contributes to more environmentally sustainable practices.
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To understand the effects of globalization and fragmentation, macromarketing scholars need insights about links between individual consumer behavior and societal outcomes. The challenge in this regard is to create a program of macrooriented cross-cultural research. This article offers a crosscultural consumer behavior research framework for this purpose. The framework encompasses four key areas of consumer behavior that are related to the forces of globalization and fragmentation, including the environment, identity, wellbeing,and market structure and policy. A discussion of these substantive areas is followed by a suggested macro-microoriented research agenda and a call for paradigm plurality in pursuing this agenda.
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ABSTRACT. The phenomenon of consumer co-creation is often framed in terms of whether either economic market forces or socio-cultural non-market forces ultimately dominate. We propose an alternate model of consumer co-creation in terms of co-evolution between markets and non-markets. Our model is based on a recent ethnographic study of a massively multiplayer online game through its development, release and ultimate failure, and cast in terms of two explanatory models: multiple games and social network markets. We conclude that consumer co-creation is indeed complex, but in ways that relate to both emergent market expectations and the evolution of markets, not to the transcendence of markets.
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Cultural policy settings attempting to foster the growth and development of the Australian feature film industry in era of globalisation are coming under increasing pressure. Global forces and emerging production and distribution models are challenging the “narrowness” of cultural policy – mandating a particular film culture, circumscribing certain notions of value and limiting the variety of films produced through cultural policy driven subvention models. Australian horror film production is an important case study. Horror films are a production strategy well suited to the financial limitations of the Australian film industry with competitive advantages for producers against international competitors. However, emerging within a “national” cinema driven by public subsidy and social/cultural objectives, horror films – internationally oriented with a low-culture status – have been severely marginalised within public funding environments. This paper introduces Australian horror film production, and examines the limitations of cultural policy, and the impacts of these questions for the Producer Offset.
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A complete change of career forces a seismic shift in every aspect of your life. From day one, you have to face the loss of long held beliefs, behaviours, the known world of self, and security. We came from professions that themselves are poles apart, and many of the challenges we faced entering the profession were the same: juggling full-time work, part time study, and family commitmemts, taking a pay cut, and loss of social life. But over a short period of time we both transitioned to our new profession successfully. so what make our successful transition possible?
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Non-motorized public transport (NMPT), especially three-wheeler cycle rickshaws, has a long history in East Asia; and has long been a major transport planning issue. Policy measures to restrict or eliminate NMPT have already been implemented in many developing cities with mixed success. However given the economic, social and cultural significance of NMPT, its environmental benefits, and the magnitude of its role in sustaining the mobility needs of citizens, it is timely to reconsider the future role of NMPT. Rather than pursuing policies to eliminate NMPT, a better approach may be to integrate motorized and non-motorized vehicles as complementary rather than competitive forces. With this backdrop and given the international significance of the problem, this paper examines the current role and significance of NMPT using Dhaka as a case study, and sets a research agenda for the future of NMPT in a sustainable transport system.
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Top screw pullout occurs when the screw is under too much axial force to remain secure in the vertebral body. In vitro biomechanical pullout tests are commonly done to find the maximum fixation strength of anterior vertebral body screws. Typically, pullout tests are done instantaneously where the screw is inserted and then pulled out immediately after insertion. However, bone is a viscoelastic material so it shows a time dependent stress and strain response. Because of this property, it was hypothesised that creep occurs in the vertebral trabecular bone due to the stress caused by the screw. The objective of this study was therefore to determine whether the axial pullout strength of anterior vertebral body screws used for scoliosis correction surgery changes with time after insertion. This study found that there is a possible relationship between pullout strength and time; however more testing is required as the sample numbers were quite small. The design of the screw is made with the knowledge of the strength it must obtain. This is important to prevent such occurrences as top screw pullout. If the pullout strength is indeed decreased due to creep, the design of the screw may need to be changed to withstand greater forces.
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This paper examines knowledge management and innovation in the Australian Construction Industry. A conceptual model is presented, based upon analysis of the literature and a series of preliminary construction industry interviews. Extensive knowledge management (KM) research has focused upon types of knowledge contained within specific organizational settings. However, we argue that a crucial missing link in KM research concerns the interface between flows of knowledge from external sources of innovations and its channelization in and out, and between organizations. This interface, regulating and facilitating knowledge from external sources of innovation into the organisation, operates under the influence of two main forces visualized as “pulling” and “pushing” forces in the model presented in this paper. The premise of the model lies in a hypothesis that as an organization changes itself into a more mature, learning organization (LO) over time, knowledge flows into it through “pull” rather than “push” forces. We conclude that a successful knowledge management initiative installs a learning and knowledge sharing culture, which is easily adaptable to new learning offering little resistance to new knowledge that flows into the organisation. The model bridges the gap between research and its application in construction practice.
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The knee forces and moments estimated by inverse dynamics and directly measured by a multiaxial transducer were compared during the gait of a transfemoral amputee. The estimated and directly measured forces and moments were relatively close. However, 3D inverse dynamics estimated only partially the forces and moments associated with the deformation of the prosthetic foot and locking of knee mechanism.