6,569 research outputs found

    Spatial Entanglement From Off-Diagonal Long Range Order in a BEC

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    We investigate spatial entanglement - particle-number entanglement between regions of space - in an ideal Bosonic gas. We quantify the amount spatial entanglement around the transition temperature for condensation by probing the gas with two localised two-level systems. We show that spatial entanglement in the gas is directly related to filling of the ground state energy level and therefore to the off-diagonal long-range order of the system and the onset of condensation.Comment: 7 pages, 3 figures. Extended from 4 to 7 pages. More detailed derivations of key formula. Extended introduction and background. Results remain unchange

    Magnetic Hole Formation from the Perspective of Inverse Scattering Theory

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    The dynamics of oblique, weakly dispersive nonlinear Alfven waves in the presence of weak resistive damping are investigated numerically through an extension of the derivative nonlinear Schrodinger (DNLS) equation. It is observed numerically that the nonlinear dynamics are organized around the dynamics and allowed interactions of the underlying DNLS soliton families. There are three types of oblique Alfven solitons: the compressive two-parameter soliton and one-parameter bright soliton along with the rare factive one-parameter dark soliton. The damping of either of these compressive solitons is accompanied by the formation of one or more dark solitons. The implication of these processes is that any initial wave profile containing solitons in its Inverse Scattering Transformation representation, in the presence of weak resistive damping, will result in a leading train of dark solitons. These dark soliton shave been identified with magnetic holes, and the results described above are discussed in the context of magnetic hole observations and theory

    Equilibrium and Disorder-induced behavior in Quantum Light-Matter Systems

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    We analyze equilibrium properties of coupled-doped cavities described by the Jaynes-Cummings- Hubbard Hamiltonian. In particular, we characterize the entanglement of the system in relation to the insulating-superfluid phase transition. We point out the existence of a crossover inside the superfluid phase of the system when the excitations change from polaritonic to purely photonic. Using an ensemble statistical approach for small systems and stochastic-mean-field theory for large systems we analyze static disorder of the characteristic parameters of the system and explore the ground state induced statistics. We report on a variety of glassy phases deriving from the hybrid statistics of the system. On-site strong disorder induces insulating behavior through two different mechanisms. For disorder in the light-matter detuning, low energy cavities dominate the statistics allowing the excitations to localize and bunch in such cavities. In the case of disorder in the light- matter coupling, sites with strong coupling between light and matter become very significant, which enhances the Mott-like insulating behavior. Inter-site (hopping) disorder induces fluidity and the dominant sites are strongly coupled to each other.Comment: about 10 pages, 12 figure

    Microfabricated silicon biosensors for microphysiometry

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    Microphysiometers are biosensor devices that measure the metabolic rate of living cells by detecting the rate of extracellular acidification caused by a small number of cells. The cells are entrapped in a microvolume chamber, whose bottom surface is a silicon sensor chip. In a further miniaturization step, we have recently fabricated multichannel flow-through chips that will allow greater throughput and multiplicity. Microphysiometer technology can be applied to the detection of microorganisms. We describe the sensitive detection of bacteria and yeast. Further applications of microphysiometry to the characterization of microorganisms can be anticipated

    Non-Violent Resistance parent training and adolescent substance misuse

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    Adolescent substance misuse is increasingly being viewed as a systemic problem and several studies have shown the benefit of increased parental involvement. This article describes the evaluation of a ten-week Non-Violent Resistance (NVR) group parent training programme delivered within a Young People’s Specialist Substance Misuse Treatment Service. Eighteen participants completed questionnaires before and after the programme, and at follow-up. Eight participants also took part in semi-structured interviews. Parents reported experiencing the programme as unique and helpful, and highlighted some challenges. Measures of parental self-efficacy and goal-based outcomes showed significant improvement at the end of the programme, and improvement in parental self-efficacy remained significant at follow-up. This evaluation provides preliminary evidence that NVR parent training may be a useful intervention in this context. However, the generalisability of the data is limited and further research is needed. Practitioner points: Non-Violent Resistance parent training helps parents resist their child’s behaviour, manage their own emotional reactions, and recruit supporters from their wider network Qualitative data suggests that parents who have attended this programme experience additional benefits to those found in qualitative evaluations of other parenting interventions A group training programme delivered within a Young People’s Specialist Substance Misuse Treatment Service improves parents’ self-efficacy and helps them achieve their goals for their children.</p

    Non-Violent Resistance parent training and adolescent substance misuse

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    Adolescent substance misuse is increasingly being viewed as a systemic problem and several studies have shown the benefit of increased parental involvement. This article describes the evaluation of a ten-week Non-Violent Resistance (NVR) group parent training programme delivered within a Young People’s Specialist Substance Misuse Treatment Service. Eighteen participants completed questionnaires before and after the programme, and at follow-up. Eight participants also took part in semi-structured interviews. Parents reported experiencing the programme as unique and helpful, and highlighted some challenges. Measures of parental self-efficacy and goal-based outcomes showed significant improvement at the end of the programme, and improvement in parental self-efficacy remained significant at follow-up. This evaluation provides preliminary evidence that NVR parent training may be a useful intervention in this context. However, the generalisability of the data is limited and further research is needed. Practitioner points: Non-Violent Resistance parent training helps parents resist their child’s behaviour, manage their own emotional reactions, and recruit supporters from their wider network Qualitative data suggests that parents who have attended this programme experience additional benefits to those found in qualitative evaluations of other parenting interventions A group training programme delivered within a Young People’s Specialist Substance Misuse Treatment Service improves parents’ self-efficacy and helps them achieve their goals for their children.</p

    Coping Behaviour as an Adaptation to Stress: Post-Disturbance Preening in Colonial Seabirds

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    In humans, coping behaviour is an action taken to soothe oneself during or after a stressful or threatening situation. Some human behaviours with physiological functions also serve as coping behaviours, for example, comfort sucking in infants and comfort eating in adults. In birds, the behaviour of preening, which has important physiological functions, has been postulated to soothe individuals after stressful situations. We combine two existing modelling approaches – logistic regression and Darwinian dynamics – to explore theoretically how a behaviour with crucial physiological function might evolve into a coping behaviour. We apply the method to preening in colonial seabirds to investigate whether and how preening might be co-opted as a coping behaviour in the presence of predators. We conduct an in-depth study of the environmental correlates of preening in a large gull colony in Washington, USA, and we perform an independent field test for comfort preening by computing the change in frequency of preening in gulls that were alerted to a predator, but did not flee
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