2,124 research outputs found

    Spinoza

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    "Spinoza", second edition. Encyclopedia entry for the Springer Encyclopedia of EM Phil and the Sciences, ed. D. Jalobeanu and C. T. Wolfe

    Connecting up strategy: are senior strategy directors a missing link?

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    With companies being exhorted to become more strategically agile and internally connected, this article examines the role of the Senior Strategy Director, the executive tasked specifically with internal strategy. In particular, it explores what they do, what specific capabilities they deploy to enable effective contribution to the company, and in what ways they facilitate the connectedness of strategy. An analysis of multiple interviews over time with Senior Strategy Directors of large companies shows the vital and challenging role these executives play in both shaping, connecting up, and executing strategy. This article identifies the particular capabilities necessary for Senior Strategy Directors to perform their role and shows how it all depends upon their skilful deployment. These findings have significant implications for understanding unfolding micro-processes of strategy in large organizations, for assumptions about the skills and capabilities necessary to be an effective Senior Strategy Director, and for business schools in terms of the content and style of strategy courses they provide

    Langevin Trajectories between Fixed Concentrations

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    We consider the trajectories of particles diffusing between two infinite baths of fixed concentrations connected by a channel, e.g. a protein channel of a biological membrane. The steady state influx and efflux of Langevin trajectories at the boundaries of a finite volume containing the channel and parts of the two baths is replicated by termination of outgoing trajectories and injection according to a residual phase space density. We present a simulation scheme that maintains averaged fixed concentrations without creating spurious boundary layers, consistent with the assumed physics

    Generalized Ensemble and Tempering Simulations: A Unified View

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    From the underlying Master equations we derive one-dimensional stochastic processes that describe generalized ensemble simulations as well as tempering (simulated and parallel) simulations. The representations obtained are either in the form of a one-dimensional Fokker-Planck equation or a hopping process on a one-dimensional chain. In particular, we discuss the conditions under which these representations are valid approximate Markovian descriptions of the random walk in order parameter or control parameter space. They allow a unified discussion of the stationary distribution on, as well as of the stationary flow across each space. We demonstrate that optimizing the flow is equivalent to minimizing the first passage time for crossing the space, and discuss the consequences of our results for optimizing simulations. Finally, we point out the limitations of these representations under conditions of broken ergodicity.Comment: 11 pages Latex, 2 eps figures, revised version, typos corrected, PRE in pres

    Diffusion in the Continuous-Imaginary-Time Quantum World-Line Monte Carlo Simulations with Extended Ensembles

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    The dynamics of samples in the continuous-imaginary-time quantum world-line Monte Carlo simulations with extended ensembles are investigated. In the case of a conventional flat ensemble on the one-dimensional quantum S=1 bi-quadratic model, the asymmetric behavior of Monte Carlo samples appears in the diffusion process in the space of the number of vertices. We prove that a local diffusivity is asymptotically proportional to the number of vertices, and we demonstrate the asymmetric behavior in the flat ensemble case. On the basis of the asymptotic form, we propose the weight of an optimal ensemble as 1/n1/\sqrt{n}, where nn denotes the number of vertices in a sample. It is shown that the asymmetric behavior completely vanishes in the case of the proposed ensemble on the one-dimensional quantum S=1 bi-quadratic model.Comment: 4 pages, 2 figures, update a referenc

    Chromosomes of the Asian flying squirrel Petaurista petaurista (Pallas)

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    Хромосомы были изучаны летаги Petaurista petaurista из Ингии; диплоидное число (2 n ) было 38 и число аутосом плечи (NF) было 72. Родство между хромосомами рода Petaurista и рода Glaucomys подсемейства Petauristinae, и Между Petaurista и Sciurus (подсемейство Sciurinae) было описывано. Находка, что диплондное число Petauristia было 38, оказывала понятие, что родовые Sciuridae обладали 2 n =38–40.Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/42484/1/18_2005_Article_BF02286944.pd

    On central tendency and dispersion measures for intervals and hypercubes

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    The uncertainty or the variability of the data may be treated by considering, rather than a single value for each data, the interval of values in which it may fall. This paper studies the derivation of basic description statistics for interval-valued datasets. We propose a geometrical approach in the determination of summary statistics (central tendency and dispersion measures) for interval-valued variables

    Monte Carlo Methods for Rough Free Energy Landscapes: Population Annealing and Parallel Tempering

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    Parallel tempering and population annealing are both effective methods for simulating equilibrium systems with rough free energy landscapes. Parallel tempering, also known as replica exchange Monte Carlo, is a Markov chain Monte Carlo method while population annealing is a sequential Monte Carlo method. Both methods overcome the exponential slowing associated with high free energy barriers. The convergence properties and efficiency of the two methods are compared. For large systems, population annealing initially converges to equilibrium more rapidly than parallel tempering for the same amount of computational work. However, parallel tempering converges exponentially and population annealing inversely in the computational work so that ultimately parallel tempering approaches equilibrium more rapidly than population annealing.Comment: 10 pages, 3 figure

    Disparate Rates of Molecular Evolution in Cospeciating Hosts and Parasites

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    DNA sequences for the gene encoding mitochondrial cytochrome oxidase I in a group of rodents (pocket gophers) and their ectoparasites (chewing lice) provide evidence for cospeciation and reveal different rates of molecular evolution in the hosts and their parasites. The overall rate of nucleotide substitution (both silent and replacement changes) is approximately three times higher in lice, and the rate of synonymous substitution (based on analysis of fourfold degenerate sites) is approximately an order of magnitude greater in lice. The difference in synonymous substitution rate between lice and gophers correlates with a difference of similar magnitude in generation times
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