1,605 research outputs found

    Teleportation of a quantum state of a spatial mode with a single massive particle

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    Mode entanglement exists naturally between regions of space in ultra-cold atomic gases. It has, however, been debated whether this type of entanglement is useful for quantum protocols. This is due to a particle number superselection rule that restricts the operations that can be performed on the modes. In this paper, we show how to exploit the mode entanglement of just a single particle for the teleportation of an unknown quantum state of a spatial mode. We detail how to overcome the superselection rule to create any initial quantum state and how to perform Bell state analysis on two of the modes. We show that two of the four Bell states can always be reliably distinguished, while the other two have to be grouped together due to an unsatisfied phase matching condition. The teleportation of an unknown state of a quantum mode thus only succeeds half of the time.Comment: 12 pages, 1 figure, this paper was presented at TQC 2010 and extends the work of Phys. Rev. Lett. 103, 200502 (2009

    The sound of violets: the ethnographic potency of poetry?

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    This paper takes the form of a dialogue between the two authors, and is in two halves, the first half discursive and propositional, and the second half exemplifying the rhetorical, epistemological and metaphysical affordances of poetry in critically scrutinising the rhetoric, epistemology and metaphysics of educational management discourse. Phipps and Saunders explore, through ideas and poems, how poetry can interrupt and/or illuminate dominant values in education and in educational research methods, such as: • alternatives to the military metaphors – targets, strategies and the like – that dominate the soundscape of education; • the kinds and qualities of the cognitive and feeling spaces that might be opened up by the shifting of methodological boundaries; • the considerable work done in ethnography on the use of the poetic: anthropologists have long used poetry as a medium for expressing their sense of empathic connection to their field and their subjects, particularly in considering the creativity and meaning-making that characterise all human societies in different ways; • the particular rhetorical affordances of poetry, as a discipline, as a practice, as an art, as patterned breath; its capacity to shift phonemic, and therewith methodological, authority; its offering of redress to linear and reductive attempts at scripting social life, as always already given and without alternative

    Anomalous spectral weight in photoemission spectra of the hole doped Haldane chain Y2-xSrxBaNiO5

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    In this paper, we present photoemission experiments on the hole doped Haldane chain compound Y2xSrxBaNiO5Y_{2-x}Sr_xBaNiO_5. By using the photon energy dependence of the photoemission cross section, we identified the symmetry of the first ionisation states (d type). Hole doping in this system leads to a significant increase in the spectral weight at the top of the valence band without any change in the vicinity of the Fermi energy. This behavior, not observed in other charge transfer oxides at low doping level, could result from the inhomogeneous character of the doped system and from a Ni 3d-O 2p hybridization enhancement due to the shortening of the relevant Ni-O distance in the localized hole-doped regions.Comment: 5 pages, 4 figure

    Resistance and Resistance Fluctuations in Random Resistor Networks Under Biased Percolation

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    We consider a two-dimensional random resistor network (RRN) in the presence of two competing biased percolations consisting of the breaking and recovering of elementary resistors. These two processes are driven by the joint effects of an electrical bias and of the heat exchange with a thermal bath. The electrical bias is set up by applying a constant voltage or, alternatively, a constant current. Monte Carlo simulations are performed to analyze the network evolution in the full range of bias values. Depending on the bias strength, electrical failure or steady state are achieved. Here we investigate the steady-state of the RRN focusing on the properties of the non-Ohmic regime. In constant voltage conditions, a scaling relation is found between /0/_0 and V/V0V/V_0, where is the average network resistance, 0_0 the linear regime resistance and V0V_0 the threshold value for the onset of nonlinearity. A similar relation is found in constant current conditions. The relative variance of resistance fluctuations also exhibits a strong nonlinearity whose properties are investigated. The power spectral density of resistance fluctuations presents a Lorentzian spectrum and the amplitude of fluctuations shows a significant non-Gaussian behavior in the pre-breakdown region. These results compare well with electrical breakdown measurements in thin films of composites and of other conducting materials.Comment: 15 figures, 23 page

    Longevity of daily oral Vitamin D3 supplementation:Differences in 25OHD and 24,25(OH)2D observed 2 years after cessation of a 1-year randomized controlled trial (VICtORy RECALL)

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    Purpose To determine the longevity of vitamin D status following cessation of vitamin D3 supplementation, 2 and 3 years after a 1 year randomised double blind placebo controlled trial: (Vitamin D and Cardiovascular Risk (VICtORY)); and to investigate possible predictive factors. Method Of the 305 Caucasian non-smoking postmenopausal women randomised to ViCtORY (2009-2010), participants who had not taken vitamin D supplements since the trial ended were invited to attend follow up visits. Total 25-hydroxyvitamin D (25OHD) and 24,25-dihydroxyvitamin D (24,25OH2D) were measured by dual tandem mass spectrometry of serum samples following removal of protein and de-lipidation; the original RCT samples were re-analysed simultaneously. Vitamin D binding protein (VDBP) was measured by monoclonal immunoassay. Results In March 2012 and March 2013, 159 women (mean (SD) age 67.6 (2.1) years) re-attended, distributed between the original treatment groups: daily vitamin D3 400IU; 1000IU; and placebo. One month after the RCT ended (March 2010) the proportion of women in placebo, 400IU, and 1000IU vitamin D3 groups, respectively, with 25OHD0.001, n=46,44,54); 42%, 33%, 12% (2y, p=0.002,n=50,48,57) and 45%, 27%, 29% (3y, p=0.138, n=47,45,51,). VDBP was a predictor of circulating 25OHD longevity (beta for VDBP in µg/ml:0.736; 95% CI 0.216-1.255,p=0.006) but not 24,25OH2D

    The adipocyte: a model for integration of endocrine and metabolic signaling in energy metabolism regulation

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    The ability to ensure continuous availability of energy despite highly variable supplies in the environment is a major determinant of the survival of all species. In higher organisms, including mammals, the capacity to efficiently store excess energy as triglycerides in adipocytes, from which stored energy could be rapidly released for use at other sites, was developed. To orchestrate the processes of energy storage and release, highly integrated systems operating on several physiological levels have evolved. The adipocyte is no longer considered a passive bystander, because fat cells actively secrete many members of the cytokine family, such as leptin, tumor necrosis factor-alpha, and interleukin-6, among other cytokine signals, which influence peripheral fuel storage, mobilization, and combustion, as well as energy homeostasis. The existence of a network of adipose tissue signaling pathways, arranged in a hierarchical fashion, constitutes a metabolic repertoire that enables the organism to adapt to a wide range of different metabolic challenges, such as starvation, stress, infection, and short periods of gross energy excess

    Recent advances in understanding Cushing disease: resistance to glucocorticoid negative feedback and somatic USP8 mutations

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    Cushing’s disease is a rare disease with a characteristic phenotype due to significant hypercortisolism driven by over-secretion of adrenocorticotropic hormone and to high morbidity and mortality if untreated. It is caused by a corticotroph adenoma of the pituitary, but the exact mechanisms leading to tumorigenesis are not clear. Recent advances in molecular biology such as the discovery of somatic mutations of the ubiquitin-specific peptidase 8 (USP8) gene allow new insights into the pathogenesis, which could be translated into exciting and much-needed therapeutic applications

    The role of peer physical activity champions in the workplace: a qualitative study

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    Aims: Peer health champions are suggested as an important component of multilevel workplace interventions to promote healthy behaviours such as physical activity. There is accumulating quantitative evidence of their effectiveness but as yet little exploration of why and how champions influence the behaviour of their peers. The current study explores the role of peer physical activity champions (PPACs) in influencing colleagues’ physical activity behaviour from the perspectives of both champions and colleagues. Methods: Seven months after the introduction of a workplace physical activity programme in 17 small and medium sized enterprices (SMEs) two focus groups were held with PPACs and four with programme participants. Focus groups were semi-structured and topics covered included: the influence of PPACs and other colleagues on their physical activity, characteristics of an effective PPAC and feelings about the PPAC role. Data were analysed using inductive thematic analysis. Results: Three overarching themes emerged: how PPACs encourage physical activity; valuable PPAC characteristics; and sustaining motivation for the PPAC role. Both direct encouragement from PPACs and facilitation of wider physical activity supportive social networks within the workplace encouraged behaviour change. Physical activity behaviour change is a delicate subject and it was important that PPACs provided enthusiastic and persistent encouragement without seeming judgemental. Being a physical activity role model was also a valuable characteristic. The PPACs found it satisfying to see positive changes in their colleagues who had become more active. However, colleagues often did not engage in suggested activities and PPACs required resilience to maintain personal motivation for the role despite this. Conclusions: The results indicate that it is feasible to incorporate PPACs into SME based physical activity interventions. Given the importance that participants attached to feeling part of a group of individuals with a common aim of increasing their physical activity, it is recommended that PPAC training includes suggestions for facilitating social connections between colleagues. Sensitivity is required when initiating and engaging in conversations with colleagues about increasing their physical activity and therefore brief motivational interviewing training may be helpful for PPACs. Programmes should ensure PPACs themselves are provided with social support, especially from others in the same role, to help sustain motivation for their role. These findings will be useful to health-promotion professionals developing workplace health programmes. Future research should explore the processes by which peer health champions facilitate changes in a range of health behaviours to identify common and behaviour specific recommendations
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