302,658 research outputs found

    Dynamic Model and Phase Transitions for Liquid Helium

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    This article presents a phenomenological dynamic phase transition theory -- modeling and analysis -- for superfluids. As we know, although the time-dependent Ginzburg-Landau model has been successfully used in superconductivity, and the classical Ginzburg-Landau free energy is still poorly applicable to liquid helium in a quantitative sense. The study in this article is based on 1) a new dynamic classification scheme of phase transitions, 2) new time-dependent Ginzburg-Landau models for general equilibrium transitions, and 3) the general dynamic transition theory. The results in this article predict the existence of a unstable region H, where both solid and liquid He II states appear randomly depending on fluctuations and the existence of a switch point M on the lambda-curve, where the transitions changes types

    Utility of a Special Second Scalar Doublet

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    This Brief Review deals with the recent resurgence of interest in adding a second scalar doublet (eta^+,eta^0) to the Standard Model of particle interactions. In most studies, it is taken for granted that eta^0 should have a nonzero vacuum expectation value, even if it may be very small. What if there is an exactly conserved symmetry which ensures =0? The phenomenological ramifications of this idea include dark matter, radiative neutrino mass, leptogenesis, and grand unification.Comment: 9 pages, 1 figur

    Supersymmetric U(1) Gauge Realization of the Dark Scalar Doublet Model of Radiative Neutrino Mass

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    Adding a second scalar doublet (eta^+,eta^0) and three neutral singlet fermions N_{1,2,3} to the Standard Model of particle interactions with a new Z_2 symmetry, it has been shown that Re(eta^0) or Im(eta^0) is a good dark-matter candidate and seesaw neutrino masses are generated radiatively. A supersymmetric U(1) gauge extension of this new idea is proposed, which enforces the usual R parity of the Minimal Supersymmetric Standard Model, and allows this new Z_2 symmetry to emerge as a discrete remnant.Comment: 8 pages, 3 figure

    A Remark on Soliton Equation of Mean Curvature Flow

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    In this short note, we consider self-similar immersions F:RnRn+kF: \mathbb{R}^n \to \mathbb{R}^{n+k} of the Graphic Mean Curvature Flow of higher co-dimension. We show that the following is true: Let F(x)=(x,f(x)),xRnF(x) = (x,f(x)), x \in \mathbb{R}^{n} be a graph solution to the soliton equation Hˉ(x)+F(x)=0. \bar{H}(x) + F^{\bot}(x) = 0. Assume supRnDf(x)C0<+\sup_{\mathbb{R}^{n}}|Df(x)| \le C_{0} < + \infty. Then there exists a unique smooth function f:RnRkf_{\infty}: \mathbb{R}^{n}\to \mathbb{R}^k such that f(x)=limλfλ(x) f_{\infty}(x) = \lim_{\lambda \to \infty}f_{\lambda}(x) and f(rx)=rf(x) f_{\infty}(r x)=r f_{\infty}(x) for any real number r0r\not= 0, where fλ(x)=λ1f(λx). f_{\lambda}(x) = \lambda^{-1}f(\lambda x). Comment: 6 page

    Muscle Fatigue Analysis Using OpenSim

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    In this research, attempts are made to conduct concrete muscle fatigue analysis of arbitrary motions on OpenSim, a digital human modeling platform. A plug-in is written on the base of a muscle fatigue model, which makes it possible to calculate the decline of force-output capability of each muscle along time. The plug-in is tested on a three-dimensional, 29 degree-of-freedom human model. Motion data is obtained by motion capturing during an arbitrary running at a speed of 3.96 m/s. Ten muscles are selected for concrete analysis. As a result, the force-output capability of these muscles reduced to 60%-70% after 10 minutes' running, on a general basis. Erector spinae, which loses 39.2% of its maximal capability, is found to be more fatigue-exposed than the others. The influence of subject attributes (fatigability) is evaluated and discussed

    Osgood-Hartogs type properties of power series and smooth functions

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    We study the convergence of a formal power series of two variables if its restrictions on curves belonging to a certain family are convergent. Also analyticity of a given CC^\infty function ff is proved when the restriction of ff on analytic curves belonging to some family is analytic. Our results generalize two known statements: a theorem of P. Lelong and the Bochnak-Siciak Theorem. The questions we study fall into the category of "Osgood-Hartogs-type" problems.Comment: 13 page