2,977 research outputs found

    H\"older Regularity of Geometric Subdivision Schemes

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    We present a framework for analyzing non-linear Rd\mathbb{R}^d-valued subdivision schemes which are geometric in the sense that they commute with similarities in Rd\mathbb{R}^d. It admits to establish C1,αC^{1,\alpha}-regularity for arbitrary schemes of this type, and C2,αC^{2,\alpha}-regularity for an important subset thereof, which includes all real-valued schemes. Our results are constructive in the sense that they can be verified explicitly for any scheme and any given set of initial data by a universal procedure. This procedure can be executed automatically and rigorously by a computer when using interval arithmetics.Comment: 31 pages, 1 figur

    Quark-Hadron Phase Transitions in Viscous Early Universe

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    Based on hot big bang theory, the cosmological matter is conjectured to undergo QCD phase transition(s) to hadrons, when the universe was about 110μ1-10 \mus old. In the present work, we study the quark-hadron phase transition, by taking into account the effect of the bulk viscosity. We analyze the evolution of the quantities relevant for the physical description of the early universe, namely, the energy density ρ\rho, temperature TT, Hubble parameter HH and scale factor aa before, during and after the phase transition. To study the cosmological dynamics and the time evolution we use both analytical and numerical methods. By assuming that the phase transition may be described by an effective nucleation theory (prompt {\it first-order} phase transition), we also consider the case where the universe evolved through a mixed phase with a small initial supercooling and monotonically growing hadronic bubbles. The numerical estimation of the cosmological parameters, aa and HH for instance, makes it clear that the time evolution varies from phase to phase. As the QCD era turns to be fairly accessible in the high-energy experiments and the lattice QCD simulations, the QCD equation of state is very well defined. In light of this, we introduce a systematic study of the {\it cross-over} quark-hadron phase transition and an estimation for the time evolution of Hubble parameter.Comment: 27 pages, 17 figures, revtex style (To appear in Phys. Rev. D). arXiv admin note: text overlap with arXiv:gr-qc/040404

    Cross-Dimensional relaxation in Bose-Fermi mixtures

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    We consider the equilibration rate for fermions in Bose-Fermi mixtures undergoing cross-dimensional rethermalization. Classical Monte Carlo simulations of the relaxation process are performed over a wide range of parameters, focusing on the effects of the mass difference between species and the degree of initial departure from equilibrium. A simple analysis based on Enskog's equation is developed and shown to be accurate over a variety of different parameter regimes. This allows predictions for mixtures of commonly used alkali atoms.Comment: 7 pages, 4 figures, uses Revtex 4. This is a companion paper to [PRA 70, 021601(R) (2004)] (cond-mat/0405419

    Sub-milliKelvin spatial thermometry of a single Doppler cooled ion in a Paul trap

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    We report on observations of thermal motion of a single, Doppler-cooled ion along the axis of a linear radio-frequency quadrupole trap. We show that for a harmonic potential the thermal occupation of energy levels leads to Gaussian distribution of the ion's axial position. The dependence of the spatial thermal spread on the trap potential is used for precise calibration of our imaging system's point spread function and sub-milliKelvin thermometry. We employ this technique to investigate the laser detuning dependence of the Doppler temperature.Comment: 5 pages, 4 figure

    Improving voluntary public good provision by a non-governmental, endogenous matching mechanism : experimental evidence

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    Social norms can help to foster cooperation and to overcome the free-rider problem in private provision of public goods. This paper focuses on the enforcement of social norms by a self-introduced punishment and reward scheme. We analyse if subjects achieve to implement a norm-enforcement mechanism at their own expense by applying the theory of non-governmental norm-enforcement by Buchholz et al. (2014) in a laboratory experiment. Based on their theory without central authority and endogenously determined enforcement mechanism, we implement a two-stage public good game: At the first stage subjects determine the strength of penalty/reward on their own and in the second stage they decide on their contributions to the public good. We find that the mechanism by Buchholz et al. (2014) leads to a higher public good contribution than without the use of any mechanism. Only in a few cases groups end up with a zero enforcement mechanism. This result indicates that subjects are apparently willing to contribute funds for implementing an enforcement mechanism. Moreover, higher enforcement parameters lead to higher public good contributions in the second stage, although too high enforcement parameters lead to unreachable theoretical optima

    Reciprocity relations between ordinary temperature and the Frieden-Soffer's Fisher-temperature

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    Frieden and Soffer conjectured some years ago the existence of a ``Fisher temperature" T_F that would play, with regards to Fisher's information measure I, the same role that the ordinary temperature T plays vis-a-vis Shannon's logarithmic measure. Here we exhibit the existence of reciprocity relations between T_F and T and provide an interpretation with reference to the meaning of T_F for the canonical ensemble.Comment: 3 pages, no figure

    Programming DNA Tube Circumferences

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    Synthesizing molecular tubes with monodisperse, programmable circumferences is an important goal shared by nanotechnology, materials science, and supermolecular chemistry. We program molecular tube circumferences by specifying the complementarity relationships between modular domains in a 42-base single-stranded DNA motif. Single-step annealing results in the self-assembly of long tubes displaying monodisperse circumferences of 4, 5, 6, 7, 8, 10, or 20 DNA helices

    Self-replication and evolution of DNA crystals

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    Is it possible to create a simple physical system that is capable of replicating itself? Can such a system evolve interesting behaviors, thus allowing it to adapt to a wide range of environments? This paper presents a design for such a replicator constructed exclusively from synthetic DNA. The basis for the replicator is crystal growth: information is stored in the spatial arrangement of monomers and copied from layer to layer by templating. Replication is achieved by fragmentation of crystals, which produces new crystals that carry the same information. Crystal replication avoids intrinsic problems associated with template-directed mechanisms for replication of one-dimensional polymers. A key innovation of our work is that by using programmable DNA tiles as the crystal monomers, we can design crystal growth processes that apply interesting selective pressures to the evolving sequences. While evolution requires that copying occur with high accuracy, we show how to adapt error-correction techniques from algorithmic self-assembly to lower the replication error rate as much as is required

    Thermodynamic cost of reversible computing

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    Since reversible computing requires preservation of all information throughout the entire computational process, this implies that all errors that appear as a result of the interaction of the information-carrying system with uncontrolled degrees of freedom must be corrected. But this can only be done at the expense of an increase in the entropy of the environment corresponding to the dissipation, in the form of heat, of the ``noisy'' part of the system's energy. This paper gives an expression of that energy in terms of the effective noise temperature, and analyzes the relationship between the energy dissipation rate and the rate of computation. Finally, a generalized Clausius principle based on the concept of effective temperature is presented.Comment: 5 pages; added two paragraphs and fixed a number of typo

    Dynamic roughening and fluctuations of dipolar chains

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    Nonmagnetic particles in a carrier ferrofluid acquire an effective dipolar moment when placed in an external magnetic field. This fact leads them to form chains that will roughen due to Brownian motion when the magnetic field is decreased. We study this process through experiments, theory and simulations, three methods that agree on the scaling behavior over 5 orders of magnitude. The RMS width goes initially as t1/2t^{1/2}, then as t1/4t^{1/4} before it saturates. We show how these results complement existing results on polymer chains, and how the chain dynamics may be described by a recent non-Markovian formulation of anomalous diffusion.Comment: 4 pages, 3 figures, submitted to Phys. Rev. Let
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