Durham Research Online

    Quantum random walks using quantum accelerator modes.

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    We discuss the use of high-order quantum accelerator modes to achieve an atom optical realization of a biased quantum random walk. We first discuss how one can create coexistent quantum accelerator modes, and hence how momentum transfer that depends on the atoms' internal state can be achieved. When combined with microwave driving of the transition between the states, a different type of atomic beam splitter results. This permits the realization of a biased quantum random walk through quantum accelerator

    Manifestation of quantum resonances and antiresonances in a finite temperature dilute atomic gas.

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    We investigate the effect of temperature on resonant and antiresonant dynamics in a dilute atomic gas kicked periodically by a standing-wave laser field. Our numerical calculations are based on a Monte Carlo method for an incoherent mixture of noninteracting plane waves, and show that the atomic dynamics are highly sensitive to the initial momentum width of the gas. We explain this sensitivity by examining the time evolution of individual atomic center-of-mass momentum eigenstates with varying quasimomentum, and we determine analytic expressions for the evolution of the second-order momentum moment to illustrate the range of behaviors

    The evolution of a UK regional tobacco control office in its early years : social contexts and policy dynamics.

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    The Smoke Free North East Office (SFNEO) is the first dedicated tobacco control office in the UK coordinating a regional tobacco control network, Smoke Free North East (SFNE). On the basis of ethnographic research conducted between 2006 and 2008, this article examines the context for SFNEO's emergence at this time and in this region of England, and the main policy and practice challenges it has faced in its early years. SFNE formed in a favourable political and cultural climate, although regional champions were crucial in setting it up. It has worked well in branding itself and in taking advantage of the opportunity to lobby in support of comprehensive smoke-free legislation, although the success of the legislation presents a risk that people will regard SFNE's work as finished. There is a need for independent sustainable funding, strong partnership working and the ‘bringing together’ of existing organizations under its leadership for an organization such as SFNE to succeed. SFNE offers a model that is transferable to other places as well as to other public health concerns such as alcohol, and has been taken up by public health planners and policy makers with alacrity. This indicates a general perception that SFNE plays an effective role in public health delivery

    Anthropology of caesarean section birth and breastfeeding : rationale for evolutionary medicine on the postnatal ward.

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    Investigating biology and behaviour in the context of evolution enables the public, scientists and medical professionals to better understand the impact of particular medical care on human physiology and emotions. Evolutionary medicine is a useful starting point because recognition of the possible mismatches between an individual’s predisposition to interact a certain way and the environment in which he or she is found can lead to practical improvements. Human parturition and postnatal care are salient examples of how culturally constructed beliefs can inhibit appropriate somatic and psychological support. Our research examines birth events, feeding strategies and the attitudes underlying them in order to better understand how modes of delivery and postnatal arrangements affect breastfeeding outcomes, maternal satisfaction and safety

    A millennial-scale record of Arctic Ocean sea ice variability and the demise of the Ellesmere Island ice shelves.

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    Sea-ice ice shelves, at the apex of North America (>80N), constitute the oldest sea ice in the Northern Hemisphere. We document the establishment and subsequent stability of the Ward Hunt Ice Shelf, and multiyear landfast sea ice in adjacent fiords, using 69 radiocarbon dates obtained on Holocene driftwood deposited prior to coastal blockage. These dates (47 of which are new) record a hiatus in driftwood deposition beginning 5500 cal yr BP, marking the inception of widespread multiyear landfast sea ice across northern Ellesmere Island. This chronology, together with historical observations of ice shelf breakup (1950 to present), provides the only millennial-scale record of Arctic Ocean sea ice variability to which the past three decades of satellite surveillance can be compared. Removal of the remaining ice shelves would be unprecedented in the last 5500 years. This highlights the impact of ongoing 20th and 21st century climate warming that continues to break up the remaining ice shelves and soon may cause historically ice-filled fiords nearby to open seasonally

    Informationalising matter : systems understandings of the nanoscale.

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    Themes of mastery, domination and power are familiar to any scholar of modern technology. Science is commonly cast as enabling the technological control over both the natural and physical worlds. Indeed, Francis Bacon famously equated scientific knowledge with power itself—stating that ‘knowledge itself is a power’ (Bacon in Montagu 1825, 71). Bacon’s now ubiquitous phrase—commonly repeated as the banal ‘knowledge is power’—was an attempt to combat three heresies in scriptural interpretation by asserting the conjunction between biblical knowledge and divine power. Opening his critique of the heresies he states: ‘You err, not knowing the scriptures nor the power of God’. In this sense the equation made between knowledge and power is of cosmic significance for Bacon in that knowledge is fundamentally associated with divine power. This image of scientific knowledge, method and rationality is deeply seductive. In this Baconian mode scientific method is irreducibly associated with human mastery over natural systems and the material world. In this image science and technology are defined as a kind of power over the physical world—the power of knowledge, method and the logos over nature, myth and irrationality (Winner 1978). In its original Latin sense—ipsa scientia potestas est—the word that translates in English as simply power is a in fact a specific type of power. Potestas is defined as ‘power over’—with particular resonances with political and juridical traditions in Roman law. That is, knowledge is equated not simply with personal capacity. Rather, knowledge produces the power of mastery, domination and coercion..

    Helping our students : learning, metalearning, and threshold concepts.

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    Supporting students through responding to variation in students' disciplinary learning, developing metalearning capacity, and focusing on the effective teaching and learning of threshold concepts - concepts that transform student understanding

    Working in isolation.

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    The key finding from our research was that professional isolation remains a major issue for today’s sessional GPs. We found that sessional GPs had limited access to information about education, clinical systems and professional support structures. This included missing out on information cascades from deaneries and PCTs relating to education,up-to-date guidelines and services, vacancies and career opportunities. There were limited opportunities for professionalpeer interaction, for example to receive feedback; discuss significant events, challenging cases and new clinical updates, and to benchmark against peers. This lack of professional interaction was often the result of not being invited to practice meetings, or them being held during days on which they were not working. These findings have significant implications regarding revalidation in terms of the way these doctors work, integrate and are supported

    An optimising approach to alternative clustering schemes.

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    Clustering objects into groups is usually done using a statistical heuristic or an optimisation. The method depends on the size of the problem and its purpose. There may exist a number of partitions which do not differ significantly but some of which may be preferable (or equally good) when aspects of the problem not formally contained in the model are considered in the interpretation of the result. To decide between a number of good partitions they must first be enumerated and this may be done by using a number of different heuristics. In this paper an alternative method is described which uses an integer linear programming model having the number and size distribution of groups as objectives and the criteria for group membership as constraints. The model is applied to three problems each having a different measure of dissimilarity between objects and so different membership criteria. In each case a number of optimal solutions are found and expressed in two parts: a core of groups, the membership of which does not change, and the remaining objects which augment the core. The core is found to contain over three quarters of the objects and so provides a stable base for cluster definition

    Isotopic investigation of diet and residential mobility in the Neolithic of the Lower Rhine Basin.

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    Multiple isotopic systems (C, N, O, S, Sr, Pb) are applied to investigate diet and mobility amongst the Middle Neolithic populations at Schipluiden and Swifterbant (Netherlands). A review of carbon and nitrogen isotope analyses of European Mesolithic and Neolithic populations shows a shift in diet from the Mesolithic to the Neolithic, but also great variety in Neolithic diets, several of which incorporate fish. At Swifterbant (c.4300—4000 BC) the population had a diet largely based on terrestrial and freshwater resources, despite proximity to tidal waters. Only one individual (of 10) showed evidence for migration. In contrast at Schipluiden (c.3600—3400 BC) there were migrants who had a diet lower in marine resources than those without evidence for migration. The faunal spectrum and isotopic similarities with sites in the Iron Gates Gorge suggest that sturgeon may have been important. There is some evidence that migrants at Schipluiden were not accorded the formal burial given to locally born people
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