21,594 research outputs found
Generalized Hurst exponent and multifractal function of original and translated texts mapped into frequency and length time series
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 and the derived curves
of the original and translated texts show marked differences. The original
"texts" are far from giving a parabolic 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 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
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 with yr.
Unless a sample of 20 super-stable millisecond pulsars can be found --- those
with timing residuals from red-noise contributions ns
--- a much larger timing program on MSPs will be needed. For
other values of , the constraint is . 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
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
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
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
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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