3,511 research outputs found

    Theory of impedance networks: The two-point impedance and LC resonances

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    We present a formulation of the determination of the impedance between any two nodes in an impedance network. An impedance network is described by its Laplacian matrix L which has generally complex matrix elements. We show that by solving the equation L u_a = lambda_a u_a^* with orthonormal vectors u_a, the effective impedance between nodes p and q of the network is Z = Sum_a [u_{a,p} - u_{a,q}]^2/lambda_a where the summation is over all lambda_a not identically equal to zero and u_{a,p} is the p-th component of u_a. For networks consisting of inductances (L) and capacitances (C), the formulation leads to the occurrence of resonances at frequencies associated with the vanishing of lambda_a. This curious result suggests the possibility of practical applications to resonant circuits. Our formulation is illustrated by explicit examples.Comment: 21 pages, 3 figures; v4: typesetting corrected; v5: Eq. (63) correcte

    Remarks on NonHamiltonian Statistical Mechanics: Lyapunov Exponents and Phase-Space Dimensionality Loss

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    The dissipation associated with nonequilibrium flow processes is reflected by the formation of strange attractor distributions in phase space. The information dimension of these attractors is less than that of the equilibrium phase space, corresponding to the extreme rarity of nonequilibrium states. Here we take advantage of a simple model for heat conduction to demonstrate that the nonequilibrium dimensionality loss can definitely exceed the number of phase-space dimensions required to thermostat an otherwise Hamiltonian system.Comment: 5 pages, 2 figures, minor typos correcte

    A Multicriteria Analysis on the Strategies to Open Taiwan's Mobile Virtual Network Operators Services

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    [[abstract]]This study investigates the trends followed by MVNOs (Mobile Virtual Network Operators) in the last three years and analyzes the strategies that can contribute to the success of Taiwan's telecommunications industry and marketing. We apply the method and concept of PATTERN (Planning Assistance Through Technical Evaluation of Relevance Number) to establish relevant systems for searching out the key successful factors of strategies to attract MVNOs. We also use the fuzzy Multi-Criteria Decision Making (MCDM) method for analyzing the different preference of a decision group in the criteria weights and for ranking the alternatives in a fuzzy environment in order to provide a strategy scheme. These results provide a reference to assist telecommunications operators, 3G license owners, potential MVNOs, and equipment manufacturers when working out business plans.[[incitationindex]]SCI[[booktype]]ē“™

    Angular Dependences of Third Harmonic Generation from Microdroplets

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    We present experimental and theoretical results for the angular dependence of third harmonic generation (THG) of water droplets in the micrometer range (size parameter 62<ka<24862<ka<248). The THG signal in pp- and ss-polarization obtained with ultrashort laser pulses is compared with a recently developed nonlinear extension of classical Mie theory including multipoles of order lā‰¤250l\leq250. Both theory and experiment yield over a wide range of size parameters remarkably stable intensity maxima close to the forward and backward direction at ``magic angles''. In contrast to linear Mie scattering, both are of comparable intensity.Comment: 4 pages, RevTeX, 3 figures available on request from [email protected], submitted to PR

    Two-frequency shell model for hypernuclei and meson-exchange hyperon-nucleon potentials

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    A two-frequency shell model is proposed for investigating the structure of hypernuclei starting with a hyperon-nucleon potential in free space. In a calculation using the folded-diagram method for Ī›Ā¹ā¶O, the Ī› single particle energy is found to have a saturation minimum at an oscillator frequency ħĻ‰Ī›ā‰ˆ10MeV, for the Ī› orbit, which is considerably smaller than ħĻ‰N=14MeV for the nucleon orbit. The spin-dependence parameters derived from the Nijmegen NSC89 and NSC97f potentials are similar, but both are rather different from those obtained with the JĆ¼lich-B potential. The Ī›NN three-body interactions induced by Ī›N-Ī£N transitions are important for the spin parameters, but relatively unimportant for the low-lying states of Ī›Ā¹ā¶O.Yiharn Tzeng, S. Y. Tsay Tzeng, T. T. S. Kuo, T.-S.H. Lee, and V. G. D. Stok

    Spanning Trees on Graphs and Lattices in d Dimensions

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    The problem of enumerating spanning trees on graphs and lattices is considered. We obtain bounds on the number of spanning trees NSTN_{ST} and establish inequalities relating the numbers of spanning trees of different graphs or lattices. A general formulation is presented for the enumeration of spanning trees on lattices in dā‰„2d\geq 2 dimensions, and is applied to the hypercubic, body-centered cubic, face-centered cubic, and specific planar lattices including the kagom\'e, diced, 4-8-8 (bathroom-tile), Union Jack, and 3-12-12 lattices. This leads to closed-form expressions for NSTN_{ST} for these lattices of finite sizes. We prove a theorem concerning the classes of graphs and lattices L{\cal L} with the property that NSTāˆ¼expā”(nzL)N_{ST} \sim \exp(nz_{\cal L}) as the number of vertices nā†’āˆžn \to \infty, where zLz_{\cal L} is a finite nonzero constant. This includes the bulk limit of lattices in any spatial dimension, and also sections of lattices whose lengths in some dimensions go to infinity while others are finite. We evaluate zLz_{\cal L} exactly for the lattices we considered, and discuss the dependence of zLz_{\cal L} on d and the lattice coordination number. We also establish a relation connecting zLz_{\cal L} to the free energy of the critical Ising model for planar lattices L{\cal L}.Comment: 28 pages, latex, 1 postscript figure, J. Phys. A, in pres

    Diffusion Processes on Small-World Networks with Distance-Dependent Random-Links

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    We considered diffusion-driven processes on small-world networks with distance-dependent random links. The study of diffusion on such networks is motivated by transport on randomly folded polymer chains, synchronization problems in task-completion networks, and gradient driven transport on networks. Changing the parameters of the distance-dependence, we found a rich phase diagram, with different transient and recurrent phases in the context of random walks on networks. We performed the calculations in two limiting cases: in the annealed case, where the rearrangement of the random links is fast, and in the quenched case, where the link rearrangement is slow compared to the motion of the random walker or the surface. It has been well-established that in a large class of interacting systems, adding an arbitrarily small density of, possibly long-range, quenched random links to a regular lattice interaction topology, will give rise to mean-field (or annealed) like behavior. In some cases, however, mean-field scaling breaks down, such as in diffusion or in the Edwards-Wilkinson process in "low-dimensional" small-world networks. This break-down can be understood by treating the random links perturbatively, where the mean-field (or annealed) prediction appears as the lowest-order term of a naive perturbation expansion. The asymptotic analytic results are also confirmed numerically by employing exact numerical diagonalization of the network Laplacian. Further, we construct a finite-size scaling framework for the relevant observables, capturing the cross-over behaviors in finite networks. This work provides a detailed account of the self-consistent-perturbative and renormalization approaches briefly introduced in two earlier short reports.Comment: 36 pages, 27 figures. Minor revisions in response to the referee's comments. Furthermore, some typos were fixed and new references were adde

    Probabilistic Bisimulation: Naturally on Distributions

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    In contrast to the usual understanding of probabilistic systems as stochastic processes, recently these systems have also been regarded as transformers of probabilities. In this paper, we give a natural definition of strong bisimulation for probabilistic systems corresponding to this view that treats probability distributions as first-class citizens. Our definition applies in the same way to discrete systems as well as to systems with uncountable state and action spaces. Several examples demonstrate that our definition refines the understanding of behavioural equivalences of probabilistic systems. In particular, it solves a long-standing open problem concerning the representation of memoryless continuous time by memory-full continuous time. Finally, we give algorithms for computing this bisimulation not only for finite but also for classes of uncountably infinite systems

    Prognostic Significance of Preoperative and Postoperative Ca 19ā€“9 Normalization in Pancreatic Adenocarcinoma Treated With Neoadjuvant Therapy or Surgery First

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    BACKGROUND: Normal(ization) of serum carbohydrate 19-9 (CA19-9) before/after surgery has not been compared in patients with pancreatic adenocarcinoma (PDAC) treated with neoadjuvant therapy (NT) versus surgery-first (SF). METHODS: Characteristics for patients with PDAC who underwent resection from July 2011 to October 2018 were collected. Patients with pre-/postoperative CA19-9, bilirubin/dL, and initial CA19-9ā€‰\u3eā€‰1ā€‰U/ml were included. Overall survival (OS) and recurrence-free survival (RFS) were compared by pre-/postoperative CA19-9. RESULTS: In patients receiving NT, normal pre/postoperative CA19-9 ( NT CONCLUSIONS: While a normal(ized) postoperative CA19-9 may result in similar survival as preoperative normal(ization), postoperative normalization failed to occur in nearly 30% of SF patients. NT should be considered in patients presenting with elevated CA19-9. If considering SF, ideal patients may include those with normal CA19-9 at presentation
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