9,846 research outputs found
Genetic Diversity and Potential Function of Microbial Symbionts Associated with Newly Discovered Species of Osedax Polychaete Worms
We investigated the genetic diversity of symbiotic bacteria associated with two newly discovered species of Osedax from Monterey Canyon, CA, at 1,017-m (Osedax Monterey Bay sp. 3 "rosy" [Osedax sp. MB3]) and 381-m (Osedax Monterey Bay sp. 4 "yellow collar") depths. Quantitative PCR and clone libraries of 16S rRNA gene sequences identified differences in the compositions and abundances of bacterial phylotypes associated with the newly discovered host species and permitted comparisons between adult Osedax frankpressi and juveniles that had recently colonized whalebones implanted at 2,891 m. The newly discovered Osedax species hosted Oceanospirillales symbionts that are related to Gammaproteobacteria associated with the previously described O. frankpressi and Osedax rubiplumus (S. K. Goffredi, V. J. Orphan, G. W. Rouse, L. Jahnke, T. Embaye, K. Turk, R. Lee, and R. C. Vrijenhoek, Environ. Microbiol. 7:1369-1378, 2005). In addition, Osedax sp. MB3 hosts a diverse and abundant population of additional bacteria dominated by Epsilonproteobacteria. Ultrastructural analysis of symbiont-bearing root tissues verified the enhanced microbial diversity of Osedax sp. MB3. Root tissues from the newly described host species and O. frankpressi all exhibited collagenolytic enzyme activity, which covaried positively with the abundance of symbiont DNA and negatively with mean adult size of the host species. Members of this unusual genus of bone-eating worms may form variable associations with symbiotic bacteria that allow for the observed differences in colonization and success in whale fall environments throughout the world's oceans
Light Element Synthesis in High Entropy Relativistic Flows Associated with Gamma Ray Bursts
We calculate and discuss the light element freeze-out nucleosynthesis in high
entropy winds and fireballs for broad ranges of entropy-per-baryon, dynamic
timescales characterizing relativistic expansion, and neutron-to-proton ratios.
With conditions characteristic of Gamma Ray Bursts (GRBs) we find that
deuterium production can be prodigious, with final abundance values 2H/H
approximately 2%, depending on the fireball isospin, late time dynamics, and
the effects of neutron decoupling- induced high energy non-thermal nuclear
reactions. This implies that there potentially could be detectable local
enhancements in the deuterium abundance associated with GRB events.Comment: 14 pages 3 figure
Dynamics of the Fisher Information Metric
We present a method to generate probability distributions that correspond to
metrics obeying partial differential equations generated by extremizing a
functional , where is the
Fisher metric. We postulate that this functional of the dynamical variable
is stationary with respect to small variations of these
variables. Our approach enables a dynamical approach to Fisher information
metric. It allows to impose symmetries on a statistical system in a systematic
way. This work is mainly motivated by the entropy approach to nonmonotonic
reasoning.Comment: 11 page
Foundations of Quantum Discord
This paper summarizes the basics of the notion of quantum discord and how it
relates to other types of correlations in quantum physics. We take the
fundamental information theoretic approach and illustrate our exposition with a
number of simple examples.Comment: 3 pages, special issue edited by Diogo de Oliveira Soares Pinto et a
Negative thermal expansion in the plateau state of a magnetically-frustrated spinel
We report on negative thermal expansion (NTE) in the high-field,
half-magnetization plateau phase of the frustrated magnetic insulator CdCr2O4.
Using dilatometry, we precisely map the phase diagram at fields of up to 30T,
and identify a strong NTE associated with the collinear half-magnetization
plateau for B > 27T. The resulting phase diagram is compared with a microscopic
theory for spin-lattice coupling, and the origin of the NTE is identified as a
large negative change in magnetization with temperature, coming from a
nearly-localised band of spin excitations in the plateau phase. These results
provide useful guidelines for the discovery of new NTE materials.Comment: 6 pages, 2 figure
A Classical Bound on Quantum Entropy
A classical upper bound for quantum entropy is identified and illustrated,
, involving the variance
in phase space of the classical limit distribution of a given system. A
fortiori, this further bounds the corresponding information-theoretical
generalizations of the quantum entropy proposed by Renyi.Comment: Latex2e, 7 pages, publication versio
Information Flow through a Chaotic Channel: Prediction and Postdiction at Finite Resolution
We reconsider the persistence of information under the dynamics of the
logistic map in order to discuss communication through a nonlinear channel
where the sender can set the initial state of the system with finite
resolution, and the recipient measures it with the same accuracy. We separate
out the contributions of global phase space shrinkage and local phase space
contraction and expansion to the uncertainty in predicting and postdicting the
state of the system. Thus, we determine how the amplification parameter, the
time lag, and the resolution influence the possibility for communication. A
novel representation for real numbers is introduced that allows for a
visualization of the flow of information between scales.Comment: 14 pages, 13 figure
Maximum Entropy for Gravitational Wave Data Analysis: Inferring the Physical Parameters of Core-Collapse Supernovae
The gravitational wave signal arising from the collapsing iron core of a Type
II supernova progenitor star carries with it the imprint of the progenitor's
mass, rotation rate, degree of differential rotation, and the bounce depth.
Here, we show how to infer the gravitational radiation waveform of a core
collapse event from noisy observations in a network of two or more LIGO-like
gravitational wave detectors and, from the recovered signal, constrain these
source properties. Using these techniques, predictions from recent core
collapse modeling efforts, and the LIGO performance during its S4 science run,
we also show that gravitational wave observations by LIGO might have been
sufficient to provide reasonable estimates of the progenitor mass, angular
momentum and differential angular momentum, and depth of the core at bounce,
for a rotating core collapse event at a distance of a few kpc.Comment: 44 pages, 12 figures; accepted version scheduled to appear in Ap J 1
April 200
Universal geometric approach to uncertainty, entropy and information
It is shown that for any ensemble, whether classical or quantum, continuous
or discrete, there is only one measure of the "volume" of the ensemble that is
compatible with several basic geometric postulates. This volume measure is thus
a preferred and universal choice for characterising the inherent spread,
dispersion, localisation, etc, of the ensemble. Remarkably, this unique
"ensemble volume" is a simple function of the ensemble entropy, and hence
provides a new geometric characterisation of the latter quantity. Applications
include unified, volume-based derivations of the Holevo and Shannon bounds in
quantum and classical information theory; a precise geometric interpretation of
thermodynamic entropy for equilibrium ensembles; a geometric derivation of
semi-classical uncertainty relations; a new means for defining classical and
quantum localization for arbitrary evolution processes; a geometric
interpretation of relative entropy; and a new proposed definition for the
spot-size of an optical beam. Advantages of the ensemble volume over other
measures of localization (root-mean-square deviation, Renyi entropies, and
inverse participation ratio) are discussed.Comment: Latex, 38 pages + 2 figures; p(\alpha)->1/|T| in Eq. (72) [Eq. (A10)
of published version
Specific protein-protein binding in many-component mixtures of proteins
Proteins must bind to specific other proteins in vivo in order to function.
The proteins must bind only to one or a few other proteins of the of order a
thousand proteins typically present in vivo. Using a simple model of a protein,
specific binding in many component mixtures is studied. It is found to be a
demanding function in the sense that it demands that the binding sites of the
proteins be encoded by long sequences of bits, and the requirement for specific
binding then strongly constrains these sequences. This is quantified by the
capacity of proteins of a given size (sequence length), which is the maximum
number of specific-binding interactions possible in a mixture. This calculation
of the maximum number possible is in the same spirit as the work of Shannon and
others on the maximum rate of communication through noisy channels.Comment: 13 pages, 3 figures (changes for v2 mainly notational - to be more in
line with notation in information theory literature
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