67 resultados para surf zone


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The integration of phylogenetics, phylogeography and palaeoenvironmental studies is providing major insights into the historical forces that have shaped the Earth’s biomes. Yet our present view is biased towards arctic and temperate/tropical forest regions, with very little focus on the extensive arid regions of the planet. The Australian arid zone is one of the largest desert landform systems in the world, with a unique, diverse and relatively well-studied biota. With foci on palaeoenvironmental and molecular data, we here review what is known about the assembly and maintenance of this biome in the context of its physical history, and in comparison with other mesic biomes. Aridification of Australia began in the Mid-Miocene, around 15 million years, but fully arid landforms in central Australia appeared much later, around 1–4 million years. Dated molecular phylogenies of diverse taxa show the deepest divergences of arid-adapted taxa from the Mid-Miocene, consistent with the onset of desiccation. There is evidence of arid-adapted taxa evolving from mesicadapted ancestors, and also of speciation within the arid zone. There is no evidence for an increase in speciation rate during the Pleistocene, and most arid-zone species lineages date to the Pliocene or earlier. The last 0.8 million years have seen major fluctuations of the arid zone, with large areas covered by mobile sand dunes during glacial maxima. Some large, vagile taxa show patterns of recent expansion and migration throughout the arid zone, in parallel with the ice sheet-imposed range shifts in Northern Hemisphere taxa. Yet other taxa show high lineage diversity and strong phylogeographical structure, indicating persistence in multiple localised refugia over several glacial maxima. Similar to the Northern Hemisphere, Pleistocene range shifts have produced suture zones, creating the opportunity for diversification and speciation through hybridisation, polyploidy and parthenogenesis. This review highlights the opportunities that development of arid conditions provides for rapid and diverse evolutionary radiations, and re-enforces the emerging view that Pleistocene environmental change can have diverse impacts on genetic structure and diversity in different biomes. There is a clear need for more detailed and targeted phylogeographical studies of Australia’s arid biota and we suggest a framework and a set of a priori hypotheses by which to proceed.

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Most of Australia’s coastline and marine waters are crown ‘land’ and can be accessed by the public. As a result, many different users and stakeholder groups have an interest in coastal and marine planning and management decisions. As a way of analysing stakeholder involvement and interplay in coastal zone management and marine protected area (MPA) development in Australia, three case studies are presented to dissect the issues and explore common themes. The three themes are 1) Stakeholder involvement in implementing the oceans policy, 2) Stakeholder involvement in marine protected area network identification and 3) Stakeholder involvement in coastal land issues.

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One of the key issues in Australia for sustainable management of the coastal zone is that the science of climate change has not been widely used by decision-makers to inform coastal governance. There exist opportunities to enhance the dialogue between knowledge-makers and decision-makers, and universities have a key role to play in researching and fostering better linkages. At the heart of these linkages lies the principle of more informed engagement between historically disparate groups. In Australia, the new ‘Flagship’ research programme, funded by the Commonwealth Scientific and Industrial Research Organization (CSIRO), emphasizes their partnering with universities in a more systematic and collaborative manner than previously achieved in such research projects. In order to address sustainability in general and coastal adaptation to climate change in particular, interdisciplinary learning needs to occur between the social and natural sciences; also, transdisciplinary understanding of that interaction needs to be fully developed. New methods of communicative engagement such as computer visualizations and animations, together with deliberative techniques, can help policy-makers and planners reach a better understanding of the significance of the science of climate change impacts on the coast. Deeper engagement across historically disparate groups can lead to the development of epistemological and methodological synergies between social and natural scientists, adaptive learning, reflexive governance, and greater analytical and deliberative understanding among scientists, policymakers and the wider public. This understanding can lead in turn to enhance coastal governance for climate adaptation on the coast.

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Whilst the proliferation of publications on climate change science is remarkable and makes the updating of responses to impacts of climate change on coastal environments daunting, the area of policy responses is even more confusing and complex. This is because policy responses do not need to consider the science of climate change alone but also have to weigh up the social and economic implications of the impact of climate change on coastal communities. In a federated nation such as Australia this has the added complication of three tiers of Government (Federal, State and local) having to interact in order to co-ordinate any policy responses. These complications should be aided by the internationally accepted concept of Integrated Coastal Zone Management (ICZM) which has been prevalent in Australian coastal planning and management for several decades. This paper uses the State of Victoria, Australia as a case study of how Governments are responding to these challenges through using the principles of ICZM. The paper will review recent inquires and investigations in Australia and canvas the policy responses to these reviews, concentrating on the State of Victoria. The paper analyses how consistent these evolving policy responses are with ICZM and suggests lessons for other jurisdictions arising from the Victorian experience.

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The thesis explores the challenges of horizontal integration across inland catchments and the coastal zone. It presents a framework demonstrating the relationship between five factors which influence horizontal integration. From this relationship it devises a set of four implementation phases for enhancing horizontal integration across catchments and the coastal zone.

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Experiments were carried out to examine whether innervation zone (IZ) location remains stable at different levels of isometric contraction in the biceps brachii muscle (BB), and to determine how the proximity of the IZ affects common surface electromyography (sEMG) parameters. Twelve subjects performed maximal (MVC) and submaximal voluntary isometric contractions at 10%, 20%, 30%, 40%, 50% and 75% of MVC. sEMG signals were recorded with a 13 rows  5 columns grid of electrodes from the short head of BB. The IZ shifted in the proximal direction by up to 2.4 cm, depending upon the subject and electrode column. The mean shift of all the columns was 0.6 ± 0.4 cm (10% vs. 100% MVC, P < 0.001). This shift biased the average values of mean frequency (+21.8 ± 9.9 Hz, P < 0.001), root mean square (0.16 ± 0.15 mV, P < 0.05) and conduction velocity (1.15 ± 0.93 m/s, P < 0.01) in the channels immediately proximal to the IZ. The shift in IZ could be explained by shortening of the muscle fibers, and thus lengthening of the (distal) tendon due to increasing force. These results underline the importance of individual investigation of IZ locations before the placement of sEMG electrodes, even in isometric contractions.

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The so-called scroll shoulder tool is widely used particularly for thick section friction stir welding (FSW). However, the correlation between its shoulder flow zone weld quality and material flow quantity remains unclear. This information is important for tool design. In the present study, a scroll shoulder tool was used to FSW 20mm thick 6061 aluminum (Al) plates at a range of welding parameters. The pick-up material (PUM) by the scroll was quantified, and the effect of welding parameters and PUM on the shoulder flow zone formation and weld quality was studied. It was found that there is a positive linear relationship between the PUM and weld quality. In order to obtain a defect-free FSW weld produced by the scroll shoulder tool, scroll groove needs to be fully filled by PUM.

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Scroll shoulder tools are widely used and they do not need to be tilted during friction stir welding (FSW). However, the detailed material flow, which is important for proper scroll shoulder tool design and subsequently for forming the defect-free shoulder flow zone, has not been fully explained. In the present study, features of material flow in shoulder flow zone, during FSW of thick 6061 aluminium (Al) plates using a scroll shoulder tool were investigated. It was observed that there is a simple layer-to-layer banded structure which appears in the bottom portion of shoulder flow zone, but disappears in the top portion of this weld zone. When the scroll shoulder tool is plunged into the workpiece to a determined depth, the workpiece material is extruded by the tool pin, and pushed up into the scroll groove beneath the shoulder forming the pick-up material. During the forward movement of the tool, the central portion of pick-up material was driven downward by the root portion of pin and then it detaches from the tip portion of pin in a layer-to-layer manner to form the weld.

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The location of the Palaeo-tethys suture in Tibet has been in great dispute for past two decades. The Longmucuo-Shuanghu suture has long been considered as the Palaeo-tethys in Tibet. Restudy of the Carboniferous and Permian sequences in the north and south of this suture reveal that: (1) the Carboniferous and Permian sequence of the North Qiangtang Block is characterized by containing compound corals and intact fusulinids zones from Moscovian Fusulinella, Fusulina to Changhsingian Palaeofusulina zones; (2) the Early Permian of the South Qiangtang Block is

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The majority of bird species studied to date have molt schedules that are not concurrent with other energy demanding life history stages, an outcome assumed to arise from energetic trade-offs. Empirical studies reveal that molt is one of the most energetically demanding and perplexingly inefficient growth processes measured. Furthermore, small birds, which have the highest mass-specific basal metabolic rates (BMRm), have the highest costs of molt per gram of feathers produced. However, many small passerines, including white-plumed honeyeaters (WPHE; Lichenostomus penicillatus), breed in response to resource availability at any time of year, and do so without interrupting their annual molt. We examined the energetic cost of molt in WPHE by quantifying weekly changes in minimum resting metabolic rate (RMRmin) during a natural-molt period in 7 wild-caught birds. We also measured the energetic cost of feather replacement in a second group of WPHEs that we forced to replace an additional 25% of their plumage at the start of their natural molt period. Energy expenditure during natural molt revealed an energy conversion efficiency of just 6.9% (±0.57) close to values reported for similar-sized birds from more predictable north-temperate environments. Maximum increases in RMRmin during the molt of WPHE, at 82% (±5.59) above individual pre-molt levels, were some of the highest yet reported. Yet RMRmin maxima during molt were not coincident with the peak period of feather replacement in naturally molting or plucked birds. Given the tight relationship between molt efficiency and mass-specific metabolic rate in all species studied to date, regardless of life-history pattern (Efficiency (%) = 35.720•10-0.494BMRm; r2 = 0.944; p =<0.0001), there appears to be concomitant physiological costs entrained in the molt period that is not directly due to feather replacement. Despite these high total expenditures, the protracted molt period of WPHE significantly reduces these added costs on a daily basis.

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This paper explores the problems of judgement and representation in relation to Jewish victims of the Holocaust who occupied so-called privileged positions in the camps and ghettos. Such figures, forced to act in ways that have proven controversial both during and after the war, faced unprecedented ethical dilemmas under Nazi persecution. Taking Auschwitz survivor Primo Levi’s highly influential essay on the ‘grey zone’ as a point of departure, I examine the extreme situations confronted by prisoner doctors, an important – though little discussed – category of ‘privileged’ Jews. Investigating the synergies between history, memory and film, I focus particularly on the case of Gisella Perl, a prisoner doctor whose experiences in Auschwitz-Birkenau are represented in her memoir and a recent fiction film. The emotionally and morally fraught circumstances of prisoner doctors can never be fully understood, yet reflecting on the double binds they faced, and acknowledging the inherent problems involved in representing and judging them, enables a nuanced approach to the moral complexities of the Holocaust.