559 research outputs found
Effects of an embedding bulk fluid on phase separation dynamics in a thin liquid film
Using dissipative particle dynamics simulations, we study the effects of an
embedding bulk fluid on the phase separation dynamics in a thin planar liquid
film. The domain growth exponent is altered from 2D to 3D behavior upon the
addition of a bulk fluid, even though the phase separation occurs in 2D
geometry. Correlated diffusion measurements in the film show that the presence
of bulk fluid changes the nature of the longitudinal coupling diffusion
coefficient from logarithmic to algebraic dependence of 1/s, where s is the
distance between the two particles. This result, along with the scaling
exponents, suggests that the phase separation takes place through the Brownian
coagulation process.Comment: 6 pages, 5 figures. Accepted for publication in Europhys. Let
Elasticity of smectic liquid crystals with focal conic domains
We study the elastic properties of thermotropic smectic liquid crystals with
focal conic domains (FCDs). After the application of the controlled preshear at
different temperatures, we independently measured the shear modulus G' and the
FCD size L. We find out that these quantities are related by the scaling
relation G' ~ \gamma_{eff}/L where \gamma_{eff} is the effective surface
tension of the FCDs. The experimentally obtained value of \gamma_{\rm eff}
shows the same scaling as the effective surface tension of the layered systems
\sqrt{KB} where K and B are the bending modulus and the layer compression
modulus, respectively. The similarity of this scaling relation to that of the
surfactant onion phase suggests an universal rheological behavior of the
layered systems with defects.Comment: 14 pages, 7 figures, accepted for publication in JPC
Symmetry Representations in the Rigged Hilbert Space Formulation of Quantum Mechanics
We discuss some basic properties of Lie group representations in rigged
Hilbert spaces. In particular, we show that a differentiable representation in
a rigged Hilbert space may be obtained as the projective limit of a family of
continuous representations in a nested scale of Hilbert spaces. We also
construct a couple of examples illustrative of the key features of group
representations in rigged Hilbert spaces. Finally, we establish a simple
criterion for the integrability of an operator Lie algebra in a rigged Hilbert
space
Lateral phase separation in mixtures of lipids and cholesterol
In an effort to understand "rafts" in biological membranes, we propose phenomenological models for saturated and unsaturated lipid mixtures, and lipid-cholesterol mixtures. We consider simple couplings between the local composition and internal membrane structure, and their influence on transitions between liquid and gel membrane phases. Assuming that the gel transition temperature of the saturated lipid is shifted by the presence of the unsaturated lipid, and that cholesterol acts as an external field on the chain melting transition, a variety of phase diagrams are obtained. The phase diagrams for binary mixtures of saturated/unsaturated lipids and lipid/cholesterol are in semi-quantitative agreement with the experiments. Our results also apply to regions in the ternary phase diagram of lipid/lipid/cholesterol systems
Palmar-divergent dislocation of the scaphoid and the lunate
We describe a patient with palmar-divergent dislocation of the scaphoid and lunate. After successful closed reduction, the scapholunate and lunotriquetral ligaments were sutured through the dorsal approach, and the anterior capsule was sutured through the palmar approach. The scapholunate and lunotriquetral joints were fixed with Kirschner wires for 7 weeks. At the 1-year follow-up, magnetic resonance imaging showed no evidence of avascular necrosis of the scaphoid or lunate, and radiographs showed no evidence of the dorsal and volar intercalated segment instability patterns associated with carpal instability. However, flexion of the scaphoid and a break in Gilula’s line remained. To our knowledge, this is the first report showing treatment of palmar-divergent dislocation of the scaphoid and lunate by suturing the carpal interosseous ligaments
Domain Growth Kinetics in a Cell-sized Liposome
We investigated the kinetics of domain growth on liposomes consisting of a
ternary mixture (unsaturated phospholipid, saturated phospholipid, and
cholesterol) by temperature jump. The domain growth process was monitored by
fluorescence microscopy, where the growth was mediated by the fusion of domains
through the collision. It was found that an average domain size r develops with
time t as r ~ t^0.15, indicating that the power is around a half of the
theoretical expectation deduced from a model of Brownian motion on a
2-dimensional membrane. We discuss the mechanism of the experimental scaling
behavior by considering the elasticity of the membrane
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Evaluation of Colour Pre-processing on Patch-Based Classification of H&E-Stained Images
This paper compares the effects of colour pre-processing on the classification performance of H&E-stained images. Variations in the tissue preparation procedures, acquisition systems, stain conditions and reagents are all source of artifacts that can affect negatively computer-based classification. Pre-processing methods such as colour constancy, transfer and deconvolution have been proposed to compensate the artifacts. In this paper we compare quantitatively the combined effect of six colour pre-processing procedures and 12 colour texture descriptors on patch-based classification of H&E-stained images. We found that colour pre-processing had negative effects on accuracy in most cases – particularly when used with colour descriptors. However, some pre-processing procedures proved beneficial when employed in conjunction with classic texture descriptors such as co-occurrence matrices, Gabor filters and Local Binary Patterns
Decay of isolated surface features driven by the Gibbs-Thomson effect in analytic model and simulation
A theory based on the thermodynamic Gibbs-Thomson relation is presented which
provides the framework for understanding the time evolution of isolated
nanoscale features (i.e., islands and pits) on surfaces. Two limiting cases are
predicted, in which either diffusion or interface transfer is the limiting
process. These cases correspond to similar regimes considered in previous works
addressing the Ostwald ripening of ensembles of features. A third possible
limiting case is noted for the special geometry of "stacked" islands. In these
limiting cases, isolated features are predicted to decay in size with a power
law scaling in time: A is proportional to (t0-t)^n, where A is the area of the
feature, t0 is the time at which the feature disappears, and n=2/3 or 1. The
constant of proportionality is related to parameters describing both the
kinetic and equilibrium properties of the surface. A continuous time Monte
Carlo simulation is used to test the application of this theory to generic
surfaces with atomic scale features. A new method is described to obtain
macroscopic kinetic parameters describing interfaces in such simulations.
Simulation and analytic theory are compared directly, using measurements of the
simulation to determine the constants of the analytic theory. Agreement between
the two is very good over a range of surface parameters, suggesting that the
analytic theory properly captures the necessary physics. It is anticipated that
the simulation will be useful in modeling complex surface geometries often seen
in experiments on physical surfaces, for which application of the analytic
model is not straightforward.Comment: RevTeX (with .bbl file), 25 pages, 7 figures from 9 Postscript files
embedded using epsf. Submitted to Phys. Rev. B A few minor changes made on
9/24/9
Structural and magnetic phase diagram of CeFeAsO1-xFx and its relationship to high-temperature superconductivity
We use neutron scattering to study the structural and magnetic phase
transitions in the iron pnictides CeFeAsO1-xFx as the system is tuned from a
semimetal to a high-transition-temperature (high-Tc) superconductor through
Fluorine (F) doping x. In the undoped state, CeFeAsO develops a structural
lattice distortion followed by a stripe like commensurate antiferromagnetic
order with decreasing temperature. With increasing Fluorine doping, the
structural phase transition decreases gradually while the antiferromagnetic
order is suppressed before the appearance of superconductivity, resulting an
electronic phase diagram remarkably similar to that of the high-Tc copper
oxides. Comparison of the structural evolution of CeFeAsO1-xFx with other
Fe-based superconductors reveals that the effective electronic band width
decreases systematically for materials with higher Tc. The results suggest that
electron correlation effects are important for the mechanism of high-Tc
superconductivity in these Fe pnictides.Comment: 19 pages, 5 figure
Dynamics and spectrum of the Cesàro operator on C-infinity(R+)
[EN] The spectrum and point spectrum of the Cesaro averaging operator C acting on the Frechet space C-infinity(R+) of all C-infinity functions on the interval [0, infinity) are determined. We employ an approach via C-0-semigroup theory for linear operators. A spectral mapping theorem for the resolvent of a closed operator acting on a locally convex space is established; it constitutes a useful tool needed to establish the main result. The dynamical behaviour of C is also investigated.The research of the first two authors was partially supported by the projects MTM2013-43540-P, GVA Prometeo II/2013/013 and GVA ACOMP/2015/186 (Spain).Albanese, AA.; Bonet Solves, JA.; Ricker, WJ. (2016). Dynamics and spectrum of the Cesàro operator on C-infinity(R+). Monatshefte für Mathematik. 181:267-283. https://doi.org/10.1007/s00605-015-0863-zS267283181Albanese, A.A., Bonet, J., Ricker, W.J.: Mean ergodic operators in Fréchet spaces. Ann. Acad. Sci. Fenn. Math. 34, 401–436 (2009)Albanese, A.A., Bonet, J., Ricker, W.J.: Mean ergodic semigroups of operators. Rev. R. Acad. Cien. Serie A Mat. RACSAM 106, 299–319 (2012)Albanese, A.A., Bonet, J., Ricker, W.J.: Montel resolvents and uniformly mean ergodic semigroups of linear operators. Quaest. Math. 36, 253–290 (2013)Albanese, A.A., Bonet, J., Ricker, W.J.: Convergence of arithmetic means of operators in Fréchet spaces. J. Math. Anal. Appl. 401, 160–173 (2013)Albanese, A.A., Bonet, J., Ricker, W.J.: Uniform mean ergodicity of C 0 -semigroups in a class of in Fréchet spaces. Funct. Approx. Comment. Math. 50, 307–349 (2014)Albanese, A.A., Bonet, J., Ricker, W.J.: On the continuous Cesàro operator in certain function spaces. Positivity 19, 659–679 (2015)Albanese, A.A., Bonet, J., Ricker, W.J.: The Cesàro operator in the Fréchet spaces ℓ p + and L p - . Glasgow Math. J. (accepted)Arendt, W.: Gaussian estimates and interpolation of the spectrum in L p . Diff. Int. Equ. 7, 1153–1168 (1994)Bayart, F., Matheron, E.: Dynamics of linear operators. Cambridge Tracts in Mathematics, vol. 179. Cambridge University Press, Cambridge (2009)Boyd, D.W.: The spectrum of the Cesàro operator. Acta Sci. Math. (Szeged) 29, 31–34 (1968)Grosse-Erdmann, K.G., Manguillot, A.P.: Linear chaos. Universitext, Springer Verlag, London (2011)Hille, E.: Remarks on ergodic theorems. Trans. Am. Math. Soc. 57, 246–269 (1945)Jarchow, H.: Locally convex spaces. Teubner, Stuttgart (1981)Komura, T.: Semigroups of operators in locally convex spaces. J. Funct. Anal. 2, 258–296 (1968)Lin, M.: On the uniform ergodic theorem. Proc. Am. Math. Soc. 43, 337–340 (1974)Malgrange, B.: Idéaux de fonctions différentiables et division des distributions. Distributions, Editions École Polytechnique, Palaiseau, pp. 1–21 (2003)Meise, R., Vogt, D.: Introduction to functional analysis. Oxford Graduate Texts in Mathematics, vol. 2. The Clarendon Press. Oxford University Press, New York (1997)Seeley, R.T.: Extension of C ∞ functions defined in a half space. Proc. Am. Math. Soc. 15, 625–626 (1964)Siskakis, A.G.: Composition semigroups and the Cesàro operator. J. London Math. Soc. (2) 36, 153–164 (1987)Yosida, K.: Functional analysis. Springer, New York, Berlin, Heidelberg (1980)Valdivia, M.: Topics in locally convex spaces. North-Holland Math. Stud. 67, North-Holland, Amsterdam (1982
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