4,674 research outputs found

    Evidences of a consolute critical point in the Phase Separation regime of La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y = 0.4) single crystals

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    We report on DC and pulsed electric field sensitivity of the resistance of mixed valent Mn oxide based La(5/8-y)Pr(y)Ca(3/8)MnO(3) (y = 0.4) single crystals as a function of temperature. The low temperature regime of the resistivity is highly current and voltage dependent. An irreversible transition from high (HR) to a low resistivity (LR) is obtained upon the increase of the electric field up to a temperature dependent critical value (V_c). The current-voltage characteristics in the LR regime as well as the lack of a variation in the magnetization response when V_c is reached indicate the formation of a non-single connected filamentary conducting path. The temperature dependence of V_c indicates the existence of a consolute point where the conducting and insulating phases produce a critical behavior as a consequence of their separation.Comment: 5 pages, 6 figures, corresponding author: C. Acha ([email protected]

    Refined Simulations of the Reaction Front for Diffusion-Limited Two-Species Annihilation in One Dimension

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    Extensive simulations are performed of the diffusion-limited reaction A++B→0\to 0 in one dimension, with initially separated reagents. The reaction rate profile, and the probability distributions of the separation and midpoint of the nearest-neighbour pair of A and B particles, are all shown to exhibit dynamic scaling, independently of the presence of fluctuations in the initial state and of an exclusion principle in the model. The data is consistent with all lengthscales behaving as t1/4t^{1/4} as t→∞t\to\infty. Evidence of multiscaling, found by other authors, is discussed in the light of these findings.Comment: Resubmitted as TeX rather than Postscript file. RevTeX version 3.0, 10 pages with 16 Encapsulated Postscript figures (need epsf). University of Geneva preprint UGVA/DPT 1994/10-85

    Diffusion-Limited Annihilation with Initially Separated Reactants

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    A diffusion-limited annihilation process, A+B->0, with species initially separated in space is investigated. A heuristic argument suggests the form of the reaction rate in dimensions less or equal to the upper critical dimension dc=2d_c=2. Using this reaction rate we find that the width of the reaction front grows as t1/4t^{1/4} in one dimension and as t1/6(ln⁥t)1/3t^{1/6}(\ln t)^{1/3} in two dimensions.Comment: 9 pages, Plain Te

    College Students’ Purchase Behaviors of Single-Serve Premium Juices

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    There has been a surge in demand for premium single-serve juices, and college students may be in the forefront of this growing trend because of the perceived social status accompanied by their consumption. External influence (i.e., peer influence and social status) emerged as a component of motivation for the use of premium juices. Findings contribute to Veblen’s theory of conspicuous consumption, demonstrating that consumer motivation for status-laden products occurs even for consumable products that are relatively low cost

    The definability criterions for convex projective polyhedral reflection groups

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    Following Vinberg, we find the criterions for a subgroup generated by reflections \Gamma \subset \SL^{\pm}(n+1,\mathbb{R}) and its finite-index subgroups to be definable over A\mathbb{A} where A\mathbb{A} is an integrally closed Noetherian ring in the field R\mathbb{R}. We apply the criterions for groups generated by reflections that act cocompactly on irreducible properly convex open subdomains of the nn-dimensional projective sphere. This gives a method for constructing injective group homomorphisms from such Coxeter groups to \SL^{\pm}(n+1,\mathbb{Z}). Finally we provide some examples of \SL^{\pm}(n+1,\mathbb{Z})-representations of such Coxeter groups. In particular, we consider simplicial reflection groups that are isomorphic to hyperbolic simplicial groups and classify all the conjugacy classes of the reflection subgroups in \SL^{\pm}(n+1,\mathbb{R}) that are definable over Z\mathbb{Z}. These were known by Goldman, Benoist, and so on previously.Comment: 31 pages, 8 figure

    Functional rescue of dystrophin deficiency in mice caused by frameshift mutations using Campylobacter jejuni Cas9

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    Duchenne muscular dystrophy (DMD) is a fatal, X-linked muscle wasting disease caused by mutations in the DMD gene. In 51% of DMD cases, a reading frame is disrupted because of deletion of several exons. Here, we show that CjCas9 derived from Campylobacter jejuni can be used as a gene editing tool to correct an out-of-frame Dmd exon in Dmd knockout mice. Herein, we used Cas9 derived from S. pyogenes to generate Dmd knockout (KO) mice with a frameshift mutation in Dmd gene. Then, we expressed CjCas9, its single-guide RNA, and the eGFP gene in the tibialis anterior muscle of the Dmd KO mice using an all-in-one adeno-associated virus (AAV) vector. CjCas9 cleaved the target site in the Dmd gene efficiently in vivo and induced small insertions or deletions at the target site. This treatment resulted in conversion of the disrupted Dmd reading frame from out-of-frame to in-frame, leading to the expression of dystrophin in the sarcolemma. Importantly, muscle strength was enhanced in the CjCas9-treated muscles, without off-target mutations, indicating high efficiency and specificity of CjCas9. This work suggests that in vivo DMD frame correction, mediated by CjCas9 has great potential for the treatment of DMD and other neuromuscular diseases

    Localisation Transition of A Dynamic Reaction Front

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    We study the reaction-diffusion process A+B→∅A+B\to \emptyset with injection of each species at opposite boundaries of a one-dimensional lattice and bulk driving of each species in opposing directions with a hardcore interaction. The system shows the novel feature of phase transitions between localised and delocalised reaction zones as the injection rate or reaction rate is varied. An approximate analytical form for the phase diagram is derived by relating both the domain of reactants AA and the domain of reactants BB to asymmetric exclusion processes with open boundaries, a system for which the phase diagram is known exactly, giving rise to three phases. The reaction zone width ww is described by a finite size scaling form relating the early time growth, relaxation time and saturation width exponents. In each phase the exponents are distinct from the previously studied case where the reactants diffuse isotropically.Comment: 13 pages, latex, uses eps

    Reaction-diffusion dynamics: confrontation between theory and experiment in a microfluidic reactor

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    We confront, quantitatively, the theoretical description of the reaction-diffusion of a second order reaction to experiment. The reaction at work is \ca/CaGreen, and the reactor is a T-shaped microchannel, 10 Ό\mum deep, 200 Ό\mum wide, and 2 cm long. The experimental measurements are compared with the two-dimensional numerical simulation of the reaction-diffusion equations. We find good agreement between theory and experiment. From this study, one may propose a method of measurement of various quantities, such as the kinetic rate of the reaction, in conditions yet inaccessible to conventional methods

    A Continuum Model for Soil-Pile-Structure Interactions Under Earthquake Excitation

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    An exact analytical method for the interaction analysis of a fully coupled soil-pile-structure system under seismic excitation is investigated in this paper. Only horizontal shaking induced by harmonic SH waves was considered. The soil mass, pile and building were all considered as elastic with hysteretic type damping. Geometrically, the soil is modeled as an elastic isotropic homogeneous continuum, and both pile and structures are simplified as beam models. The structure and piles are coupled through a rigid foundation at the ground level. Buildings of various heights in Hong Kong designed to withstand wind load were analyzed using the present model. Only the shaking at the ground level is considered in this study. It was discovered that the maximum shaking of the piled-structures at ground level is generally larger than that of a free field ground shaking except near the first natural frequency of the coupled soil-pile-structure system. This first resonant frequency depends strongly on the natural frequency of the structure

    Variable stars in the Open Cluster M11 (NGC 6705)

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    V-band time-series CCD photometric observations of the intermediate-age open cluster M11 were performed to search for variable stars. Using these time-series data, we carefully examined light variations of all stars in the observing field. A total of 82 variable stars were discovered, of which 39 stars had been detected recently by Hargis et al. (2005). On the basis of observational properties such as variable period, light curve shape, and position on a color-magnitude diagram, we classified their variable types as 11 delta Scuti-type pulsating stars, 2 gamma Doradus-type pulsating stars, 40 W UMa-type contact eclipsing binaries, 13 Algol-type detached eclipsing binaries, and 16 eclipsing binaries with long period. Cluster membership for each variable star was deduced from the previous proper motion results (McNamara et al. 1977) and position on the color-magnitude diagram. Many pulsating stars and eclipsing binaries in the region of M11 are probable members of the cluster.Comment: 23 pages, 9 figures, 3 tables, and accepted for publication in PAS
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