35 resultados para Luminescence dating (OSL)

em Queensland University of Technology - ePrints Archive


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The unique combination of landscapes and processes that are present and operate on Fraser Island (K'gari) create a dynamic setting that is capable of recording past environmental events, climate variations and former landscapes. Likewise, its geographic position makes Fraser Island sensitive to those events and processes. Based on optically stimulated luminescence dating, the records archived within the world's largest sand island span a period that has the potential to exceed 750 ka and contain specific records that are of extremely high resolution over the past 40,000 years. This is due to the geographic position of Fraser Island, which lies in the coastal subtropical region of Queensland Australia. Fraser Island is exposed to the open ocean currents of the Coral Sea on the east coast and the waters of Hervey Bay on its western margin and is positioned to receive moisture from the Indo-Australian monsoon, southeast trade winds and experiences occasional tropical and ex-tropical cyclones. We review literature that presents the current level of understanding of sea level change, ecological variation and environmental change on Fraser Island. The previous works illustrate the importance of Fraser Island and may link processes, environments and climates on Fraser Island with global records.

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Moreton Island and several other large siliceous sand dune islands and mainland barrier deposits in SE Queensland represent the distal, onshore component of an extensive Quaternary continental shelf sediment system. This sediment has been transported up to 1000 km along the coast and shelf of SE Australia over multiple glacioeustatic sea-level cycles. Stratigraphic relationships and a preliminary Optically Stimulated Luminance (OSL) chronology for Moreton Island indicate a middle Pleistocene age for the large majority of the deposit. Dune units exposed in the centre of the island and on the east coast have OSL ages that indicate deposition occurred between approximately 540 ka and 350 ka BP, and at around 96±10 ka BP. Much of the southern half of the island has a veneer of much younger sediment, with OSL ages of 0.90±0.11 ka, 1.28±0.16 ka, 5.75±0.53 ka and <0.45 ka BP. The younger deposits were partially derived from the reworking of the upper leached zone of the much older dunes. A large parabolic dune at the northern end of the island, OSL age of 9.90±1.0 ka BP, and palaeosol exposures that extend below present sea level suggest the Pleistocene dunes were sourced from shorelines positioned several to tens of metres lower than, and up to few kilometres seaward of the present shoreline. Given the lower gradient of the inner shelf a few km seaward of the island, it seems likely that periods of intermediate sea level (e.g. ~20 m below present) produced strongly positive onshore sediment budgets and the mobilisation of dunes inland to form much of what now comprises Moreton Island. The new OSL ages and comprehensive OSL chronology for the Cooloola deposit, 100 km north of Moreton Island, indicate that the bulk of the coastal dune deposits in SE Queensland were emplaced between approximately 540 ka BP and prior to the Last Interglacial. This chronostratigraphic information improves our fundamental understanding of long-term sediment transport and accumulation on large-scale continental shelf sediment systems.

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We study the suggestion that Markov switching (MS) models should be used to determine cyclical turning points. A Kalman filter approximation is used to derive the dating rules implicit in such models. We compare these with dating rules in an algorithm that provides a good approximation to the chronology determined by the NBER. We find that there is very little that is attractive in the MS approach when compared with this algorithm. The most important difference relates to robustness. The MS approach depends on the validity of that statistical model. Our approach is valid in a wider range of circumstances.

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This article examines the growing phenomenon of online dating and intimacy in the 21st century. The exponential rise of communications technologies, which is both reflective and constitutive of an increasingly networked and globalized society, has the potential to significantly influence the nature of intimacy in everyday life. Yet, to date, there has been a minimal response by sociologists to seek, describe and understand this influence. In this article, we present some of the key findings of our research on online dating in Australia, in order to foster a debate about the sociological impacts on intimacy in the postmodern world. Based on a web audit of more than 60 online dating sites and in-depth interviews with 23 users of online dating services, we argue that recent global trends are influencing the uptake of online technologies for the purposes of forming intimate relations. Further, some of the mediating effects of these technologies – in particular, the hypercommunication – may have specific implications for the nature of intimacy in the global era.

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This article explores the role of sociology in understanding the phenomenon of online dating. Based on an examination of our qualitative study of 23 online daters, combined with the findings of the small number of other empirical studies available, we argue that further sociological consideration of the online dating phenomenon is required to: illuminate the social conditions informing these activities; enhance knowledge of if, and how, online technologies mediate intimate connections; and advance a critically informed understanding of the nature of intimacy in a global era.

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Due to the change in attitudes and lifestyles, people expect to find new partners and friends via various ways now-a-days. Online dating networks create a network for people to meet each other and allow making contact with different objectives of developing a personal, romantic or sexual relationship. Due to the higher expectation of users, online matching companies are trying to adopt recommender systems. However, the existing recommendation techniques such as content-based, collaborative filtering or hybrid techniques focus on users explicit contact behaviors but ignore the implicit relationship among users in the network. This paper proposes a social matching system that uses past relations and user similarities in finding potential matches. The proposed system is evaluated on the dataset collected from an online dating network. Empirical analysis shows that the recommendation success rate has increased to 31% as compared to the baseline success rate of 19%.

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Online social networks can be found everywhere from chatting websites like MSN, blogs such as MySpace to social media such as YouTube and second life. Among them, there is one interesting type of online social networks, online dating network that is growing fast. This paper analyzes an online dating network from social network analysis point of view. Observations are made and results are obtained in order to suggest a better recommendation system for people-to-people networks.

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A new relationship type of social networks - online dating - are gaining popularity. With a large member base, users of a dating network are overloaded with choices about their ideal partners. Recommendation methods can be utilized to overcome this problem. However, traditional recommendation methods do not work effectively for online dating networks where the dataset is sparse and large, and a two-way matching is required. This paper applies social networking concepts to solve the problem of developing a recommendation method for online dating networks. We propose a method by using clustering, SimRank and adapted SimRank algorithms to recommend matching candidates. Empirical results show that the proposed method can achieve nearly double the performance of the traditional collaborative filtering and common neighbor methods of recommendation.

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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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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.