8,285 research outputs found

    Orthographic vs. morphological incomplete neutralization effects

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    This study, following up on work on Dutch by Warner, Jongman, Sereno, and Kemps (2004. Journal of Phonetics, 32, 251–276), investigates the influence of orthographic distinctions and underlying morphological distinctions on the small sub-phonemic durational differences that have been called incomplete neutralization. One part of the previous work indicated that an orthographic geminate/singleton distinction could cause speakers to produce an incomplete neutralization effect. However, one interpretation of the materials in that experiment is that they contain an underlying difference in the phoneme string at the level of concatenation of morphemes, rather than just an orthographic difference. Thus, the previous effect might simply be another example of incomplete neutralization of a phonemic distinction. The current experiment, also on Dutch, uses word pairs which have the same underlying morphological contrast, but do not differ in orthography. These new materials show no incomplete neutralization, and thus support the hypothesis that orthography, but not underlying morphological differences, can cause incomplete neutralization effects

    Double precision trajectory program /DPTRAJ 2.2C/

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    Four part program computes trajectory of space probe moving in solar system and subject to variety of forces

    Enhanced Dynamic Adhesion in Nematic Liquid Crystal Elastomers.

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    Smart adhesives that undergo reversible detachment in response to external stimuli enable a wide range of applications in household products, medical devices, or manufacturing. Here, a new model system for the design of smart soft adhesives that dynamically respond to their environment is presented. By exploiting the effect of dynamic soft elasticity in nematic liquid crystal elastomers (LCE), the temperature-dependent control of adhesion to a solid glass surface is demonstrated. The adhesion strength of LCE is more than double in the nematic phase, in comparison to the isotropic phase, further increasing at higher detachment rates. The static work of adhesion, related to the interfacial energy of adhesive contact, is shown to change very little within the explored temperature range. Accordingly, the observed enhanced adhesion in the nematic phase is primarily attributable to the increased internal energy dissipation during the detachment process. This adhesion effect is correlated with the inherent bulk dynamic-mechanical response in the nematic LCE. The reported enhanced dynamic adhesion can lead to the development of a new class of stimuli-responsive adhesives.ERC Advanced Grant No: 786659 (EU) JSPS Grant No: JP17K18862 (Japan

    Dynamics, dynamic soft elasticity and rheology of smectic-C elastomers

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    We present a theory for the low-frequency, long-wavelength dynamics of soft smectic-C elastomers with locked-in smectic layers. Our theory, which goes beyond pure hydrodynamics, predicts a dynamic soft elasticity of these elastomers and allows us to calculate the storage and loss moduli relevant for rheology experiments as well as the mode structure.Comment: 4 pages, 2 figure

    Electro-Mechanical Fredericks Effects in Nematic Gels

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    The solid nematic equivalent of the Fredericks transition is found to depend on a critical field rather than a critical voltage as in the classical case. This arises because director anchoring is principally to the solid rubbery matrix of the nematic gel rather than to the sample surfaces. Moreover, above the threshold field, we find a competition between quartic (soft) and conventional harmonic elasticity which dictates the director response. By including a small degree of initial director misorientation, the calculated field variation of optical anisotropy agrees well with the conoscopy measurements of Chang et al (Phys.Rev.E56, 595, 1997) of the electro-optical response of nematic gels.Comment: Latex (revtex style), 5 EPS figures, submitted to PRE, corrections to discussion of fig.3, cosmetic change

    A warped disk model for M33 and the 21-cm line width in spiral galaxies

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    To determine the actual HI distribution and the velocity field in the outermost disk of the spiral galaxy M33, a tilted-ring model is fitted to 21-cm line data taken with the Arecibo Telescope. Since M33 is one of the main calibrators for the extragalactic distance scale derived through the Tully-Fisher relation, the outer disk warping is of interest for a correct determination and deprojection of the galaxy's line width. Even though our best model predicts small effects on the observed line width of M33, we show that similar outer disk warping in galaxies oriented differently along our line of sight could affect the widths considerably. Therefore there may be systematic effects in the determination of the rotation velocities and dynamic masses of spiral galaxies, whose exact value depends also on which method is used for measuring the galaxy's total line width.Comment: 27 pages, ps files only, ApJ in pres

    Volume Fractions of the Kinematic "Near-Critical" Sets of the Quantum Ensemble Control Landscape

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    An estimate is derived for the volume fraction of a subset CϵP={U:∣∣gradJ(U)∣≤ϵ}⊂U(N)C_{\epsilon}^{P} = \{U : ||grad J(U)|\leq {\epsilon}\}\subset\mathrm{U}(N) in the neighborhood of the critical set CP≃U(n)PU(m)C^{P}\simeq\mathrm{U}(\mathbf{n})P\mathrm{U}(\mathbf{m}) of the kinematic quantum ensemble control landscape J(U) = Tr(U\rho U' O), where UU represents the unitary time evolution operator, {\rho} is the initial density matrix of the ensemble, and O is an observable operator. This estimate is based on the Hilbert-Schmidt geometry for the unitary group and a first-order approximation of ∣∣gradJ(U)∣∣2||grad J(U)||^2. An upper bound on these near-critical volumes is conjectured and supported by numerical simulation, leading to an asymptotic analysis as the dimension NN of the quantum system rises in which the volume fractions of these "near-critical" sets decrease to zero as NN increases. This result helps explain the apparent lack of influence exerted by the many saddles of JJ over the gradient flow.Comment: 27 pages, 1 figur
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