981 resultados para U-series Dating


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The researcher was invited to photograph athletes in the lead-up to the 2006 Commonwealth Games held in Melbourne. She photographed four indigenous athletes, to produce a series of four large-scale cotton rag prints, 1 meter x 1 meter, printed onto photorag paper from digital files. “My photographic practice can be described as both political and spiritual, in the sense that as an Aboriginal Indigenous artist I take stock of the rationalising effect of the technologies I use, and create work that evokes nature and spirit. My methods often involve re-photographing or digitally re-working landscape photographs and adding historical or cultural icons of significance. Working with Indigenous athletes has been an honour and a pleasure. I admire the athletes’ passion and dedication to their chosen sport, and above all their humility, which seems a trait somewhat in contrast to what it takes to attain the highest levels of achievement. Indigenous athletes are wonderful role models for all Australians, and in making creative work that places their luminary presence with the land, I am aligning sportspeople with a deep sense of nature and spirit.” – Leah King-Smith. These works were commissioned by the National Portrait Gallery for the exhibition FLASH: Australian Athletes in Focus. The exhibition was a significant element in Melbourne2006 Festival, the cultural festival of the Commonwealth Games. The exhibition was prominently reviewed in Portrait: Magazine of Australian and International Portraiture and was subsequently remounted at Old Parliament House, Canberra (15 July to 12 November, 2006). One image was used for the front cover of Art Monthly, (March 2006).

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The nature and possibilities for intimacy between adults are changing in the mobile era. Bauman (2003) has decreed this the era of ‘liquid love’, in which intimacy is commodified and committed relationships have been replaced by fleeting connections. In contrast, Giddens (1991; 1993) suggests that the reordering of everyday life in late-stage modernity has given rise to the possibility of a democratization of interpersonal interaction, characterized by reflexive ‘pure relationships’. The purpose of this paper is to consider theoretical debates about intimacy in the mobile era with regard to the contemporary practice of online dating. Drawing on our qualitative research with 23 online daters in Australia, we argue that, while the architecture of online dating is consistent with liquid love, many online daters simultaneously desire the possibilities for consumption afforded by liquid love, while aspiring to the formation of pure relationships and/or more practical forms of caring. This creates tensions in people’s experiences of this form of purposeful meeting, which are reflective of the conflicting socialities of intimacy available to us in the mobile era. At the same time, our research revealed disruptions to these tensions, by illuminating experiences where the consumerist orientation of online dating stimulated processes of reflexive self-discovery amongst our participants.

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Dancelines was a body of work commissioned by Bangarra Dance Company and The Arts Centre, Melbourne. The artist was invited to produce a body of work that responded to the dance company's production of 'Boomerang'. The result was a body of photographs that applied the artist's interest in layering as a photographic technique and her interest in indigenous subjectivity and sprituality. The works drew correspondences between Rheannan Port, the subject's, own biography and character and the artist's voluminous archive of iamges of the natural world. The result complemented and formalised the collaborative processes that the artist had previously only explored in the video medium. The work was shown at the George Adams Gallery of the Arts Centre as part of Melbourne 2006 Commonwealth Games Arts Festival. 'Rheannan Port, #1' was selected for the 2006 Archibald Photographic Portrait Prize, at the Art Gallery of New South Wales. The work was reviewed in The Age newspaper.

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Previous research has indicated that road crashes are the most common form of work related fatalities (Haworth et al., 2000). Historically, industry has often taken a “silver bullet” approach developing and implementing a single countermeasure to address all their work related road safety issues, despite legislative requirements to discharge obligations through minimising risk and enhancing safety. This paper describes the results and implications from a series of work related road safety audits that were undertaken across five organisations to determine deficiencies in each organisation‟s safe driving management and practice. Researchers conducted a series of structured interviews, reviewed documentation relating to work related driving, and analysed vehicle related crash and incident records to determine each organisation‟s current situation in the management of work related road safety and driver behaviour. A number of consistent themes and issues across each organisation were identified relating to managing driver behaviour, organisational policies, incident recording and reporting, communication and education, and formalisation of key work related road safety strategies. Although organisations are required to undertake risk reduction strategies for all work related driving, the results of the research suggest that many organisations fail to systematically manage driver behaviour and mitigate work related road safety risk. Future improvements in work related road safety will require organisations to firstly acknowledge the high risk associated with drivers driving for work and secondly adopt comprehensive risk mitigation strategies in a similar manner to managing other workplace hazards.

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In order to make good decisions about the design of information systems, an essential skill is to understand process models of the business domain the system is intended to support. Yet, little knowledge to date has been established about the factors that affect how model users comprehend the content of process models. In this study, we use theories of semiotics and cognitive load to theorize how model and personal factors influence how model viewers comprehend the syntactical information of process models. We then report on a four-part series of experiments, in which we examined these factors. Our results show that additional semantical information impedes syntax comprehension, and that theoretical knowledge eases syntax comprehension. Modeling experience further contributes positively to comprehension efficiency, measured as the ratio of correct answers to the time taken to provide answers. We discuss implications for practice and research.

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This study investigated potential palaeoclimate proxies provided by rare earth element (REE) geochemistry in speleothems and in clay mineralogy of cave sediments. Speleothem and sediment samples were collected from a series of cave fill deposits that occurred with rich vertebrate fossil assemblages in and around Mount Etna National Park, Rockhampton (central coastal Queensland). The fossil deposits range from Plio- Pleistocene to Holocene in age (based on uranium/thorium dating) and appear to represent depositional environments ranging from enclosed rainforest to semi-arid grasslands. Therefore, the Mount Etna cave deposits offer the perfect opportunity to test new palaeoclimate tools as they include deposits that span a known significant climate shift on the basis of independent faunal data. The first section of this study investigates the REE distribution of the host limestone to provide baseline geochemistry for subsequent speleothem investigations. The Devonian Mount Etna Beds were found to be more complex than previous literature had documented. The studied limestone massif is overturned, highly recrystallised in parts and consists of numerous allochthonous blocks with different spatial orientations. Despite the complex geologic history of the Mount Etna Beds, Devonian seawater-like REE patterns were recovered in some parts of the limestone and baseline geochemistry was determined for the bulk limestone for comparison with speleothem REE patterns. The second part of the study focused on REE distribution in the karst system and the palaeoclimatic implications of such records. It was found that REEs have a high affinity for calcite surfaces and that REE distributions in speleothems vary between growth bands much more than along growth bands, thus providing a temporal record that may relate to environmental changes. The morphology of different speleothems (i.e., stalactites, stalagmites, and flowstones) has little bearing on REE distributions provided they are not contaminated with particulate fines. Thus, baseline knowledge developed in the study suggested that speleothems were basically comparable for assessing palaeoclimatically controlled variations in REE distributions. Speleothems from rainforest and semi-arid phases were compared and it was found that there are definable differences in REE distribution that can be attributed to climate. In particular during semiarid phases, total REE concentration decreased, LREE became more depleted, Y/Ho increased, La anomalies were more positive and Ce anomalies were more negative. This may reflect more soil development during rainforest phases and more organic particles and colloids, which are known to transport REEs, in karst waters. However, on a finer temporal scale (i.e. growth bands) within speleothems from the same climate regime, no difference was seen. It is suggested that this may be due to inadequate time for soil development changes on the time frames represented by differences in growth band density. The third part of the study was a reconnaissance investigation focused on mineralogy of clay cave sediments, illite/kaolinite ratios in particular, and the potential palaeoclimatic implications of such records. Although the sample distribution was not optimal, the preliminary results suggest that the illite/kaolinite ratio increased during cold and dry intervals, consistent with decreased chemical weathering during those times. The study provides a basic framework for future studies at differing latitudes to further constrain the parameters of the proxy. The identification of such a proxy recorded in cave sediment has broad implications as clay ratios could potentially provide a basic local climate proxy in the absence of fossil faunas and speleothem material. This study suggests that REEs distributed in speleothems may provide information about water throughput and soil formation, thus providing a potential palaeoclimate proxy. It highlights the importance of understanding the host limestone geochemistry and broadens the distribution and potential number of cave field sites as palaeoclimate information no longer relies solely on the presence of fossil faunas and or speleothems. However, additional research is required to better understand the temporal scales required for the proxies to be recognised.

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Divergence dating studies, which combine temporal data from the fossil record with branch length data from molecular phylogenetic trees, represent a rapidly expanding approach to understanding the history of life. National Evolutionary Synthesis Center hosted the first Fossil Calibrations Working Group (3–6 March, 2011, Durham, NC, USA), bringing together palaeontologists, molecular evolutionists and bioinformatics experts to present perspectives from disciplines that generate, model and use fossil calibration data. Presentations and discussions focused on channels for interdisciplinary collaboration, best practices for justifying, reporting and using fossil calibrations and roadblocks to synthesis of palaeontological and molecular data. Bioinformatics solutions were proposed, with the primary objective being a new database for vetted fossil calibrations with linkages to existing resources, targeted for a 2012 launch.

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In phylogenetics, the unrooted model of phylogeny and the strict molecular clock model are two extremes of a continuum. Despite their dominance in phylogenetic inference, it is evident that both are biologically unrealistic and that the real evolutionary process lies between these two extremes. Fortunately, intermediate models employing relaxed molecular clocks have been described. These models open the gate to a new field of “relaxed phylogenetics.” Here we introduce a new approach to performing relaxed phylogenetic analysis. We describe how it can be used to estimate phylogenies and divergence times in the face of uncertainty in evolutionary rates and calibration times. Our approach also provides a means for measuring the clocklikeness of datasets and comparing this measure between different genes and phylogenies. We find no significant rate autocorrelation among branches in three large datasets, suggesting that autocorrelated models are not necessarily suitable for these data. In addition, we place these datasets on the continuum of clocklikeness between a strict molecular clock and the alternative unrooted extreme. Finally, we present analyses of 102 bacterial, 106 yeast, 61 plant, 99 metazoan, and 500 primate alignments. From these we conclude that our method is phylogenetically more accurate and precise than the traditional unrooted model while adding the ability to infer a timescale to evolution.

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The timing and order of divergences within the genus Rattus have, to date, been quite speculative. In order to address these important issues we sequenced six new whole mitochondrial genomes from wild-caught specimens from four species, Rattus exulans, Rattus praetor, Rattus rattus and Rattus tanezumi. The only rat whole mitochondrial genomes available previously were all from Rattus norvegicus specimens. Our phylogenetic and dating analyses place the deepest divergence within Rattus at ∼3.5 million years ago (Mya). This divergence separates the New Guinean endemic R. praetor lineage from the Asian lineages. Within the Asian/Island Southeast Asian clade R. norvegicus diverged earliest at ∼2.9 Mya. R. exulans and the ancestor of the sister species R. rattus and R. tanezumi subsequently diverged at ∼2.2 Mya, with R. rattus and R. tanezumi separating as recently as ∼0.4 Mya. Our results give both a better resolved species divergence order and diversification dates within Rattus than previous studies.

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Despite recent methodological advances in inferring the time-scale of biological evolution from molecular data, the fundamental question of whether our substitution models are sufficiently well specified to accurately estimate branch-lengths has received little attention. I examine this implicit assumption of all molecular dating methods, on a vertebrate mitochondrial protein-coding dataset. Comparison with analyses in which the data are RY-coded (AG → R; CT → Y) suggests that even rates-across-sites maximum likelihood greatly under-compensates for multiple substitutions among the standard (ACGT) NT-coded data, which has been subject to greater phylogenetic signal erosion. Accordingly, the fossil record indicates that branch-lengths inferred from the NT-coded data translate into divergence time overestimates when calibrated from deeper in the tree. Intriguingly, RY-coding led to the opposite result. The underlying NT and RY substitution model misspecifications likely relate respectively to “hidden” rate heterogeneity and changes in substitution processes across the tree, for which I provide simulated examples. Given the magnitude of the inferred molecular dating errors, branch-length estimation biases may partly explain current conflicts with some palaeontological dating estimates.

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ABSTRACT Objectives: To investigate the effect of hot and cold temperatures on ambulance attendances. Design: An ecological time series study. Setting and participants: The study was conducted in Brisbane, Australia. We collected information on 783 935 daily ambulance attendances, along with data of associated meteorological variables and air pollutants, for the period of 2000–2007. Outcome measures: The total number of ambulance attendances was examined, along with those related to cardiovascular, respiratory and other non-traumatic conditions. Generalised additive models were used to assess the relationship between daily mean temperature and the number of ambulance attendances. Results: There were statistically significant relationships between mean temperature and ambulance attendances for all categories. Acute heat effects were found with a 1.17% (95% CI: 0.86%, 1.48%) increase in total attendances for 1 °C increase above threshold (0–1 days lag). Cold effects were delayed and longer lasting with a 1.30% (0.87%, 1.73%) increase in total attendances for a 1 °C decrease below the threshold (2–15 days lag). Harvesting was observed following initial acute periods of heat effects, but not for cold effects. Conclusions: This study shows that both hot and cold temperatures led to increases in ambulance attendances for different medical conditions. Our findings support the notion that ambulance attendance records are a valid and timely source of data for use in the development of local weather/health early warning systems.

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To cover wide range of pulsed power applications, this paper proposes a modularity concept to improve the performance and flexibility of the pulsed power supply. The proposed scheme utilizes the advantage of parallel and series configurations of flyback modules in obtaining high-voltage levels with fast rise time (dv/dt). Prototypes were implemented using 600-V insulated-gate bipolar transistor (IGBT) switches to generate up to 4-kV output pulses with 1-kHz repetition rate for experimentation. To assess the proposed modular approach for higher number of the modules, prototypes were implemented using 1700-V IGBTs switches, based on ten-series modules, and tested up to 20 kV. Conducted experimental results verified the effectiveness of the proposed method

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Purpose - The purpose of this paper is to examine the possibility of an inverted U-shaped relationship between job demands and work engagement, and whether social support moderates this relationship. Design/methodology/approach – This study uses 307 technical and information technology (IT) managers who responded to an online survey. Multiple regressions are employed to examine linear and curvilinear relationship among variables. Findings – Overall, results support the applicability of the quadratic effect of job demands on employee engagement. However, only supervisor support, not colleague support, moderated the relationship between job demands and work engagement. Originality/value – The paper is the first to shed light on the quadratic effect of job demands on work engagement. The findings have noteworthy implications for managers to design optimal job demands that increase employee engagement.