979 research outputs found

    Topography driven spreading

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    Roughening a hydrophobic surface enhances its nonwetting properties into superhydrophobicity. For liquids other than water, roughness can induce a complete rollup of a droplet. However, topographic effects can also enhance partial wetting by a given liquid into complete wetting to create superwetting. In this work, a model system of spreading droplets of a nonvolatile liquid on surfaces having lithographically produced pillars is used to show that superwetting also modifies the dynamics of spreading. The edge speed-dynamic contact angle relation is shown to obey a simple power law, and such power laws are shown to apply to naturally occurring surfaces

    Time-dependent perturbation theory for vibrational energy relaxation and dephasing in peptides and proteins

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    Without invoking the Markov approximation, we derive formulas for vibrational energy relaxation (VER) and dephasing for an anharmonic system oscillator using a time-dependent perturbation theory. The system-bath Hamiltonian contains more than the third order coupling terms since we take a normal mode picture as a zeroth order approximation. When we invoke the Markov approximation, our theory reduces to the Maradudin-Fein formula which is used to describe VER properties of glass and proteins. When the system anharmonicity and the renormalization effect due to the environment vanishes, our formulas reduce to those derived by Mikami and Okazaki invoking the path-integral influence functional method [J. Chem. Phys. 121 (2004) 10052]. We apply our formulas to VER of the amide I mode of a small amino-acide like molecule, N-methylacetamide, in heavy water.Comment: 16 pages, 5 figures, 5 tables, submitted to J. Chem. Phy

    Single-crossover dynamics: finite versus infinite populations

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    Populations evolving under the joint influence of recombination and resampling (traditionally known as genetic drift) are investigated. First, we summarise and adapt a deterministic approach, as valid for infinite populations, which assumes continuous time and single crossover events. The corresponding nonlinear system of differential equations permits a closed solution, both in terms of the type frequencies and via linkage disequilibria of all orders. To include stochastic effects, we then consider the corresponding finite-population model, the Moran model with single crossovers, and examine it both analytically and by means of simulations. Particular emphasis is on the connection with the deterministic solution. If there is only recombination and every pair of recombined offspring replaces their pair of parents (i.e., there is no resampling), then the {\em expected} type frequencies in the finite population, of arbitrary size, equal the type frequencies in the infinite population. If resampling is included, the stochastic process converges, in the infinite-population limit, to the deterministic dynamics, which turns out to be a good approximation already for populations of moderate size.Comment: 21 pages, 4 figure

    Routinely used interventions to improve attachment in infants and young children: a national survey and two systematic reviews.

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    BACKGROUND: Attachment refers to an infant's innate tendency to seek comfort from their caregiver. Research shows that attachment is important in promoting healthy social and emotional development. Many parenting interventions have been developed to improve attachment outcomes for children. However, numerous interventions used in routine practice have a limited evidence base, meaning that we cannot be sure if they are helpful or harmful. OBJECTIVES: This research aimed to conduct a large-scale survey to identify what interventions are being used in UK services to improve child attachment; conduct a systematic review to evaluate the evidence for parenting attachment interventions; and develop recommendations for future research and practice. DESIGN AND METHODS: We worked closely with our Expert Reference Group to plan a large-scale survey focused on relevant UK services. We then conducted two systematic reviews. One searched for all randomised controlled trial evidence for any attachment parenting intervention. The second searched for all research for the top 10 routinely used interventions identified from the survey. RESULTS: The survey collected 625 responses covering 734 UK services. The results identified the 10 most commonly used interventions. The responses showed a limited use of validated measures and a wide variety of definitions of attachment. For the first review, seven studies were included from 2516 identified records. These were combined with results from previous reviews conducted by the team. Meta-analyses showed that, overall, parenting interventions are effective in reducing disorganised attachment (pooled odds ratio 0.54, 95% confidence interval 0.39 to 0.77) and increasing secure attachment (pooled odds ratio 1.85, 95% confidence interval 1.36 to 2.52). The second review searched the literature for the top 10 routinely used interventions identified by the survey; 61 studies were included from 1198 identified records. The results showed that many of the most commonly used interventions in UK services have a weak evidence base and those with the strongest evidence base are not as widely used. CONCLUSIONS: There is a need for better links between research and practice to ensure that interventions offered to families are safe and effective. Possible reasons for the disparity include the cost and accessibility of training. There is also a need for improved understanding by professionals regarding the meaning of attachment. LIMITATIONS: Although the survey had good geographical spread, most respondents were based in England. For review 2 we were unable to access a large number of papers; however, we conducted extensive reference checking to account for this. FUTURE WORK: There is a need for robust research to test the efficacy of routinely used attachment interventions. Research could also explore why routinely used interventions are not consistently subject to thorough evaluation; how to embed dissemination, cost-effectiveness, fidelity and sustainability into research; and how to keep clinical practice up to date with research developments. STUDY REGISTRATION: This study is registered as PROSPERO CRD42019137362. FUNDING: This project was funded by the National Institute for Health and Care Research (NIHR) Health Technology Assessment programme and will be published in full in Health Technology Assessment; Vol. 27, No. 2. See the NIHR Journals Library website for further project information

    “some kind of thing it aint us but yet its in us”: David Mitchell, Russell Hoban, and metafiction after the millennium

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    This article appraises the debt that David Mitchell’s Cloud Atlas owes to the novels of Russell Hoban, including, but not limited to, Riddley Walker. After clearly mapping a history of Hoban’s philosophical perspectives and Mitchell’s inter-textual genre-impersonation practice, the article assesses the degree to which Mitchell’s metatextual methods indicate a nostalgia for by-gone radical aesthetics rather than reaching for new modes of its own. The article not only proposes several new backdrops against which Mitchell’s novel can be read but also conducts the first in-depth appraisal of Mitchell’s formal linguistic replication of Riddley Walker
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