112 research outputs found
Information dynamics: Temporal behavior of uncertainty measures
We carry out a systematic study of uncertainty measures that are generic to
dynamical processes of varied origins, provided they induce suitable continuous
probability distributions. The major technical tool are the information theory
methods and inequalities satisfied by Fisher and Shannon information measures.
We focus on a compatibility of these inequalities with the prescribed
(deterministic, random or quantum) temporal behavior of pertinent probability
densities.Comment: Incorporates cond-mat/0604538, title, abstract changed, text
modified, to appear in Cent. Eur. J. Phy
Extrapolating SMBH correlations down the mass scale: the case for IMBHs in globular clusters
Empirical evidence for both stellar mass black holes M_bh<10^2 M_sun) and
supermassive black holes (SMBHs, M_bh>10^5 M_sun) is well established.
Moreover, every galaxy with a bulge appears to host a SMBH, whose mass is
correlated with the bulge mass, and even more strongly with the central stellar
velocity dispersion sigma_c, the `M-sigma' relation. On the other hand,
evidence for "intermediate-mass" black holes (IMBHs, with masses in the range
1^2 - 10^5 M_sun) is relatively sparse, with only a few mass measurements
reported in globular clusters (GCs), dwarf galaxies and low-mass AGNs. We
explore the question of whether globular clusters extend the M-sigma
relationship for galaxies to lower black hole masses and find that available
data for globular clusters are consistent with the extrapolation of this
relationship. We use this extrapolated M-sigma relationship to predict the
putative black hole masses of those globular clusters where existence of
central IMBH was proposed. We discuss how globular clusters can be used as a
constraint on theories making specific predictions for the low-mass end of the
M-sigma relation.Comment: 14 pages, 3 figures, accepted for publication in Astrophysics and
Space Science; fixed typos and a quote in Sec.
Long-Time Behavior of Macroscopic Quantum Systems: Commentary Accompanying the English Translation of John von Neumann's 1929 Article on the Quantum Ergodic Theorem
The renewed interest in the foundations of quantum statistical mechanics in
recent years has led us to study John von Neumann's 1929 article on the quantum
ergodic theorem. We have found this almost forgotten article, which until now
has been available only in German, to be a treasure chest, and to be much
misunderstood. In it, von Neumann studied the long-time behavior of macroscopic
quantum systems. While one of the two theorems announced in his title, the one
he calls the "quantum H-theorem", is actually a much weaker statement than
Boltzmann's classical H-theorem, the other theorem, which he calls the "quantum
ergodic theorem", is a beautiful and very non-trivial result. It expresses a
fact we call "normal typicality" and can be summarized as follows: For a
"typical" finite family of commuting macroscopic observables, every initial
wave function from a micro-canonical energy shell so evolves that for
most times in the long run, the joint probability distribution of these
observables obtained from is close to their micro-canonical
distribution.Comment: 34 pages LaTeX, no figures; v2: minor improvements and additions. The
English translation of von Neumann's article is available as arXiv:1003.213
Small Open Chemical Systems Theory and Its Implications to Darwinian Evolutionary Dynamics, Complex Self-Organization and Beyond
The study of biological cells in terms of mesoscopic, nonequilibrium,
nonlinear, stochastic dynamics of open chemical systems provides a paradigm for
other complex, self-organizing systems with ultra-fast stochastic fluctuations,
short-time deterministic nonlinear dynamics, and long-time evolutionary
behavior with exponentially distributed rare events, discrete jumps among
punctuated equilibria, and catastrophe.Comment: 15 page
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Multi-lingual and multi-cultural information literacy; perspectives, models and good practice
Purpose
This paper reviews current approaches to, and good practice, in information literacy development in multi-lingual and multi-cultural settings, with particular emphasis on provision for international students.
Design/methodology/approach
A selective and critical review of published literature is extended by evaluation of examples of multi-lingual information literacy tutorials and MOOCs.
Findings
Multi-lingual and multi-cultural information literacy are umbrella terms covering a variety of situations and issues. This provision is of increasing importance in an increasingly mobile and multi-cultural world. This article evaluates current approaches and good practice, focusing on issues of culture vis a vis language, the balance between individual and group needs, specific and generic information literacy instruction, and models for information literacy, pedagogy and culture. Recommendations for good practice and for further research are given,
Originality/value
This is one of very few articles critically reviewing how information literacy development is affected by linguistic and cultural factors
Genome-wide association study identifies nine novel loci for 2D:4D finger ratio, a putative retrospective biomarker of testosterone exposure in utero
The ratio of the length of the index finger to that of the ring finger (2D:4D) is sexually dimorphic and is commonly used as a non-invasive biomarker of prenatal androgen exposure. Most association studies of 2D:4D ratio with a diverse range of sexspecific traits have typically involved small sample sizes and have been difficult to replicate, raising questions around the utility and precise meaning of the measure. In the largest genome-wide association meta-analysis of 2D:4D ratio to date (N=15 661, with replication N=75 821), we identified 11 loci (9 novel) explaining 3.8% of the variance in mean 2D:4D ratio. We also found weak evidence for association (b=0.06; P=0.02) between 2D:4D ratio and sensitivity to testosterone [length of the CAG microsatellite repeat in the androgen receptor (AR) gene] in females only. Furthermore, genetic variants associated with (adult) testosterone levels and/or sex hormone-binding globulin were not associated with 2D:4D ratio in our sample. Although we were unable to find strong evidence from our genetic study to support the hypothesis that 2D:4D ratio is a direct biomarker of prenatal exposure to androgens in healthy individuals, our findings do not explicitly exclude this possibility, and pathways involving testosterone may become apparent as the size of the discovery sample increases further. Our findings provide new insight into the underlying biology shaping 2D:4D variation in the general population
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