550 research outputs found

    Use of data from patient records for research : a model for best practice?

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    In the UK National Health Service (NHS), the registered list and the clinical records of patients are an invaluable resource for the quality assurance of clinical care in General Practice (e.g. audit) and for service development and quality initiatives. These records are also powerful instruments for the conduct of research in primary care. General practitioners are the "guardians" of these demographic and clinical data and, indeed, the use of patient data from these records for research in the past has given us many examples of excellent research which have had a direct impact on the care of our patients and the advice we give them.peer-reviewe

    Dynamic somite cell rearrangements lead to distinct waves of myotome growth

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    The myogenic precursors responsible for muscle growth in amniotes develop from thedermomyotome, an epithelium at the external surface of the somite. In teleosts, themyogenic precursors responsible for growth have not been identified. We have usedsingle cell lineage labeling in zebrafish to show that anterior border cells of epithelialsomites are myogenic precursors responsible for zebrafish myotome growth. These cellsmove to the external surface of the embryonic myotome and express the transcriptionfactor Pax7. Some remain on the external surface and some incorporate into the fastmyotome, apparently by moving between differentiated slow fibres. The posterior cellsof the somite, in contrast, elongate into medial muscle fibres. The surprising movementof the anterior somite cells to the external somite surface transforms a segmentallyrepeated arrangement of myogenic precursors into a medio-lateral arrangement similar tothat seen in amniotes.Fil: Stellabotte, Frank. Ohio Wesleyan University.; Estados UnidosFil: Dobbs McAuliffe, Betsy. Ohio Wesleyan University.; Estados UnidosFil: Fernandez, Daniel Alfredo. Consejo Nacional de Investigaciones CientĂ­ficas y TĂ©cnicas. Centro Austral de Investigaciones CientĂ­ficas; Argentina. Universidad Nacional de Tierra del Fuego; ArgentinaFil: Feng, Xuesong. Ohio Wesleyan University.; Estados UnidosFil: Devoto, Stephen Henry. Ohio Wesleyan University.; Estados Unido

    Current-Induced Step Bending Instability on Vicinal Surfaces

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    We model an apparent instability seen in recent experiments on current induced step bunching on Si(111) surfaces using a generalized 2D BCF model, where adatoms have a diffusion bias parallel to the step edges and there is an attachment barrier at the step edge. We find a new linear instability with novel step patterns. Monte Carlo simulations on a solid-on-solid model are used to study the instability beyond the linear regime.Comment: 4 pages, 4 figure

    Modelling CO formation in the turbulent interstellar medium

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    We present results from high-resolution three-dimensional simulations of turbulent interstellar gas that self-consistently follow its coupled thermal, chemical and dynamical evolution, with a particular focus on the formation and destruction of H2 and CO. We quantify the formation timescales for H2 and CO in physical conditions corresponding to those found in nearby giant molecular clouds, and show that both species form rapidly, with chemical timescales that are comparable to the dynamical timescale of the gas. We also investigate the spatial distributions of H2 and CO, and how they relate to the underlying gas distribution. We show that H2 is a good tracer of the gas distribution, but that the relationship between CO abundance and gas density is more complex. The CO abundance is not well-correlated with either the gas number density n or the visual extinction A_V: both have a large influence on the CO abundance, but the inhomogeneous nature of the density field produced by the turbulence means that n and A_V are only poorly correlated. There is a large scatter in A_V, and hence CO abundance, for gas with any particular density, and similarly a large scatter in density and CO abundance for gas with any particular visual extinction. This will have important consequences for the interpretation of the CO emission observed from real molecular clouds. Finally, we also examine the temperature structure of the simulated gas. We show that the molecular gas is not isothermal. Most of it has a temperature in the range of 10--20 K, but there is also a significant fraction of warmer gas, located in low-extinction regions where photoelectric heating remains effective.Comment: 37 pages, 15 figures; minor revisions, matches version accepted by MNRA
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