2,393 research outputs found

    Micromagnetic Domain Structures in Cylindrical Nickel Dots

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    The magnetic domain structures of cylindrical nickel dots (diameters from 40 nm to 1700 nm) with anisotropy parallel to the cylinder axis is predicted by the ratio of the dot diameter to the stripe period of unpatterned films with the same perpendicular anisotropy. The dominant domain structure for a given ratio increases in complexity as the ratio increases. We present evidence for the full micromagnetic domain structure for the simplest cases

    Interferometric scattering enables fluorescence-free electrokinetic trapping of single nanoparticles in free solution

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    Anti-Brownian traps confine single particles in free solution by closed-loop feedback forces that directly counteract Brownian motion. The extended-duration measurement of trapped objects allows detailed characterization of photophysical and transport properties, as well as observation of infrequent or rare dynamics. However, this approach has been generally limited to particles that can be tracked by fluorescent emission. Here we present the Interferometric Scattering Anti-Brownian ELectrokinetic trap (ISABEL trap), which uses interferometric scattering rather than fluorescence to monitor particle position. By decoupling the ability to track (and therefore trap) a particle from collection of its spectroscopic data, the ISABEL trap enables confinement and extended study of single particles that do not fluoresce, that only weakly fluoresce, or which exhibit intermittent fluorescence or photobleaching. This new technique significantly expands the range of nanoscale objects that may be investigated at the single-particle level in free solution.Comment: Manuscript and SI; videos available upon reques

    Biology and Ecology of the Atlantic Stingray, Dasyatis sabina (Pisces: Dasyatidae) in North Carolina and Georgia

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    The seasonality, distribution, ecology, movements, catch per unit effort, breeding season, and length-weight relationships for the Atlantic stingray, Dasyatis sabina, trawled in North Carolina (1973 through 1976) and Georgia (1967 through 1969) are compared and discussed. Occurrences in relation to water temperature, salinity, and oxygen content are also reported and compared with previous literature. Dispelling popular belief, D. sabina throughout its range is a minor numerical component of the fish faunas studied

    Weighted maximal regularity estimates and solvability of non-smooth elliptic systems II

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    We continue the development, by reduction to a first order system for the conormal gradient, of L2L^2 \textit{a priori} estimates and solvability for boundary value problems of Dirichlet, regularity, Neumann type for divergence form second order, complex, elliptic systems. We work here on the unit ball and more generally its bi-Lipschitz images, assuming a Carleson condition as introduced by Dahlberg which measures the discrepancy of the coefficients to their boundary trace near the boundary. We sharpen our estimates by proving a general result concerning \textit{a priori} almost everywhere non-tangential convergence at the boundary. Also, compactness of the boundary yields more solvability results using Fredholm theory. Comparison between classes of solutions and uniqueness issues are discussed. As a consequence, we are able to solve a long standing regularity problem for real equations, which may not be true on the upper half-space, justifying \textit{a posteriori} a separate work on bounded domains.Comment: 76 pages, new abstract and few typos corrected. The second author has changed nam

    Resolvent Estimates in L^p for the Stokes Operator in Lipschitz Domains

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    We establish the LpL^p resolvent estimates for the Stokes operator in Lipschitz domains in RdR^d, d≄3d\ge 3 for ∣1p−1/2∣<12d+Ï”|\frac{1}{p}-1/2|< \frac{1}{2d} +\epsilon. The result, in particular, implies that the Stokes operator in a three-dimensional Lipschitz domain generates a bounded analytic semigroup in LpL^p for (3/2)-\varep < p< 3+\epsilon. This gives an affirmative answer to a conjecture of M. Taylor.Comment: 28 page. Minor revision was made regarding the definition of the Stokes operator in Lipschitz domain

    Refined asymptotics for the infinite heat equation with homogeneous Dirichlet boundary conditions

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    The nonnegative viscosity solutions to the infinite heat equation with homogeneous Dirichlet boundary conditions are shown to converge as time increases to infinity to a uniquely determined limit after a suitable time rescaling. The proof relies on the half-relaxed limits technique as well as interior positivity estimates and boundary estimates. The expansion of the support is also studied

    "Caring for Insiderness": Phenomenologically informed insights that can guide practice.

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    Understanding the ‘‘insider’’ perspective has been a pivotal strength of qualitative research. Further than this, within the more applied fields in which the human activity of ‘‘caring’’ takes place, such understanding of ‘‘what it is like’’ for people from within their lifeworlds has also been acknowledged as the foundational starting point in order for ‘‘care’’ to be caring. But we believe that more attention needs to be paid to this foundational generic phenomenon: what it means to understand the ‘‘insiderness’’ of another, but more importantly, how to act on this in caring ways. We call this human phenomenon ‘‘caring for insiderness.’’ Drawing on existing phenomenological studies of marginal caring situations at the limits of caring capability, and through a process of phenomenologically oriented reflection, we interrogated some existential themes implicit in these publications that could lead to deeper insights for both theoretical and applied purposes. The paper provides direction for practices of caring by highlighting some dangers as well as some remedies along this path

    Performance, Politics and Media: How the 2010 British General Election leadership debates generated ‘talk’ amongst the electorate.

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    During the British General Election 2010 a major innovation was introduced in part to improve engagement: a series of three live televised leadership debates took place where the leader of each of the three main parties, Labour, Liberal Democrat and Conservative, answered questions posed by members of the public and subsequently debated issues pertinent to the questions. In this study we consider these potentially ground breaking debates as the kind of event that was likely to generate discussion. We investigate various aspects of the ‘talk’ that emerged as a result of watching the debates. As an exploratory study concerned with situated accounts of the participants experiences we take an interpretive perspective. In this paper we outline the meta-narratives (of talk) associated with the viewing of the leadership debates that were identified, concluding our analysis by suggesting that putting a live debate on television and promoting and positioning it as a major innovation is likely to mean that is how the audience will make sense of it – as a media event

    Observing Interprofessional Simulation

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    © 2019, Springer Nature Switzerland AG. This chapter has a particular focus on the observers’ role in simulation-based learning activities. Simulation-based learning is often organised so that participants rotates between active participation in the scenario and participation as observers. The research examples provided show that the conditions for learning are related to the locations where and the ways the observers are situated, and to how the instructions to the observers are formulated. Arguments are put forward that the observers’ role in simulation has unexploited potential for developing skills of noticing

    Null sets of harmonic measure on NTA domains: Lipschitz approximation revisited

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    We show the David-Jerison construction of big pieces of Lipschitz graphs inside a corkscrew domain does not require its surface measure be upper Ahlfors regular. Thus we can study absolute continuity of harmonic measure and surface measure on NTA domains of locally finite perimeter using Lipschitz approximations. A partial analogue of the F. and M. Riesz Theorem for simply connected planar domains is obtained for NTA domains in space. As a consequence every Wolff snowflake has infinite surface measure.Comment: 22 pages, 6 figure
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