21,377 research outputs found

    Generalized Hurst exponent and multifractal function of original and translated texts mapped into frequency and length time series

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    A nonlinear dynamics approach can be used in order to quantify complexity in written texts. As a first step, a one-dimensional system is examined : two written texts by one author (Lewis Carroll) are considered, together with one translation, into an artificial language, i.e. Esperanto are mapped into time series. Their corresponding shuffled versions are used for obtaining a "base line". Two different one-dimensional time series are used here: (i) one based on word lengths (LTS), (ii) the other on word frequencies (FTS). It is shown that the generalized Hurst exponent h(q)h(q) and the derived f(α)f(\alpha) curves of the original and translated texts show marked differences. The original "texts" are far from giving a parabolic f(α)f(\alpha) function, - in contrast to the shuffled texts. Moreover, the Esperanto text has more extreme values. This suggests cascade model-like, with multiscale time asymmetric features as finally written texts. A discussion of the difference and complementarity of mapping into a LTS or FTS is presented. The FTS f(α)f(\alpha) curves are more opened than the LTS onesComment: preprint for PRE; 2 columns; 10 pages; 6 (multifigures); 3 Tables; 70 reference

    Minimum Requirements for Detecting a Stochastic Gravitational Wave Background Using Pulsars

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    We assess the detectability of a nanohertz gravitational wave (GW) background with respect to additive red and white noise in the timing of millisecond pulsars. We develop detection criteria based on the cross-correlation function summed over pulsar pairs in a pulsar timing array. The distribution of correlation amplitudes is found to be non-Gaussian and highly skewed, which significantly influences detection and false-alarm probabilities. When only white noise and GWs contribute, our detection results are consistent with those found by others. Red noise, however, drastically alters the results. We discuss methods to meet the challenge of GW detection ("climbing mount significance") by distinguishing between GW-dominated and red or white-noise limited regimes. We characterize detection regimes by evaluating the number of millisecond pulsars that must be monitored in a high-cadence, 5-year timing program for a GW background spectrum hc(f)=Af−2/3h_c(f) = A f^{-2/3} with A=10−15A = 10^{-15} yr−2/3^{-2/3}. Unless a sample of 20 super-stable millisecond pulsars can be found --- those with timing residuals from red-noise contributions σr≲20\sigma_r \lesssim 20 ns --- a much larger timing program on ≳50−100\gtrsim 50 - 100 MSPs will be needed. For other values of AA, the constraint is σr≲20ns(A/10−15yr−2/3)\sigma_r \lesssim 20 {\rm ns} (A/10^{-15} {\rm yr}^{-2/3}). Identification of suitable MSPs itself requires an aggressive survey campaign followed by characterization of the level of spin noise in the timing residuals of each object. The search and timing programs will likely require substantial fractions of time on new array telescopes in the southern hemisphere as well as on existing ones.Comment: Submitted to the Astrophysical Journa

    The double life of electrons in magnetic iron pnictides, as revealed by NMR

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    We present a phenomenological, two-fluid approach to understanding the magnetic excitations in Fe pnictides, in which a paramagnetic fluid with gapless, incoherent particle-hole excitations coexists with an antiferromagnetic fluid with gapped, coherent spin wave excitations. We show that this two-fluid phenomenology provides an excellent quantitative description of NMR data for magnetic "122" pnictides, and argue that it finds a natural justification in LSDA and spin density wave calculations. We further use this phenomenology to estimate the maximum renormalisation of the ordered moment that can follow from low-energy spin fluctuations in Fe pnictides. We find that this is too small to account for the discrepancy between ab intio calculations and neutron scattering measurements.Comment: Accepted for publication in Europhys. Lett. 6 pages, 4 figure

    Fluctuation Theorem with Information Exchange: Role of Correlations in Stochastic Thermodynamics

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    We establish the fluctuation theorem in the presence of information exchange between a nonequilibrium system and other degrees of freedom such as an observer and a feedback controller, where the amount of information exchange is added to the entropy production. The resulting generalized second law sets the fundamental limit of energy dissipation and energy cost during the information exchange. Our results apply not only to feedback-controlled processes but also to a much broader class of information exchanges, and provides a unified framework of nonequilibrium thermodynamics of measurement and feedback control.Comment: To appear in PR

    Information-theoretic temporal Bell inequality and quantum computation

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    An information-theoretic temporal Bell inequality is formulated to contrast classical and quantum computations. Any classical algorithm satisfies the inequality, while quantum ones can violate it. Therefore, the violation of the inequality is an immediate consequence of the quantumness in the computation. Furthermore, this approach suggests a notion of temporal nonlocality in quantum computation.Comment: v2: 5 pages, refereces added, discussion slightly revised, main result unchanged. v3: typos correcte

    Social Responsibility, Librarianship, and the ALA: The 2015 Banned Books Week Poster Controversy

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    This article explores the recent controversy over the American Library Association’s poster for Banned Books Week. In particular, this article connects the 2015 controversy to broader historical issues and tensions within American librarianship concerning social responsibilities. The researchers used a qualitative approach, conducting telephone interviews with 26 individuals. The interviews were recorded, transcribed, and analyzed deductively. The interviews revealed deep continuing tensions regarding American librarianship’s relationship to responsibilities. First, there is some dissatisfaction with the American Library Association and its Office for Intellectual Freedom. Second, there are competing conceptualizations of censorship and how to apply these differing meanings while remaining socially responsible. Third, there is uncertainty about how to appropriately act as an ally, within librarianship, to marginalized peoples
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