1,664 research outputs found
Definite Streptococcus bovis endocarditis: characteristics in 20 patients
ObjectiveTo determine the specific characteristics of Streptococcus bovis infective endocarditis (IE) by reviewing our own experience of S. bovis IE.MethodsTwenty episodes of definite S. bovis IE were reviewed in 20 patients hospitalized from 1980 to 1996.ResultsThe mean age was 62 ± 14 years, and 14 (70%) patients had no known predisposing cardiac condition. The principal antimicrobials used were penicillin G (N = 10) and amoxycillin (N = 8). Surgery was required in four (20%) patients. Neurologic complications occurred in eight (40%) patients, after initiation of therapy in six (75%) (mean time: 14 days). An unfavorable outcome was observed in four of 20 patients and tended to be more frequent in patients who had had neurologic complications (P â 0.10). Colonic tumors were present in 11 of 16 (69%) patients.ConclusionsAdvanced age, occurrence of IE on presumably normal valves, high rate of neurologic complications, associated gastrointestinal diseases and low mortality rate during initial follow-up are characteristic features of S. bovis IE observed in this study
NARROMI: a noise and redundancy reduction technique improves accuracy of gene regulatory network inference.
MOTIVATION: Reconstruction of gene regulatory networks (GRNs) is of utmost interest to biologists and is vital for understanding the complex regulatory mechanisms within the cell. Despite various methods developed for reconstruction of GRNs from gene expression profiles, they are notorious for high false positive rate owing to the noise inherited in the data, especially for the dataset with a large number of genes but a small number of samples.
RESULTS: In this work, we present a novel method, namely NARROMI, to improve the accuracy of GRN inference by combining ordinary differential equation-based recursive optimization (RO) and information theory-based mutual information (MI). In the proposed algorithm, the noisy regulations with low pairwise correlations are first removed by using MI, and the redundant regulations from indirect regulators are further excluded by RO to improve the accuracy of inferred GRNs. In particular, the RO step can help to determine regulatory directions without prior knowledge of regulators. The results on benchmark datasets from Dialogue for Reverse Engineering Assessments and Methods challenge and experimentally determined GRN of Escherichia coli show that NARROMI significantly outperforms other popular methods in terms of false positive rates and accuracy.
AVAILABILITY: All the source data and code are available at: http://csb.shu.edu.cn/narromi.htm
Classification of non-Riemannian doubled-yet-gauged spacetime
Assuming covariant fields as the `fundamental' variables,
Double Field Theory can accommodate novel geometries where a Riemannian metric
cannot be defined, even locally. Here we present a complete classification of
such non-Riemannian spacetimes in terms of two non-negative integers,
, . Upon these backgrounds, strings become
chiral and anti-chiral over and directions respectively, while
particles and strings are frozen over the directions. In
particular, we identify as Riemannian manifolds, as
non-relativistic spacetime, as Gomis-Ooguri non-relativistic string,
as ultra-relativistic Carroll geometry, and as Siegel's
chiral string. Combined with a covariant Kaluza-Klein ansatz which we further
spell, leads to Newton-Cartan gravity. Alternative to the conventional
string compactifications on small manifolds, non-Riemannian spacetime such as
, may open a new scheme of the dimensional reduction from ten to
four.Comment: 1+41 pages; v2) Refs added; v3) Published version; v4) Sign error in
(2.51) correcte
Detours and Paths: BRST Complexes and Worldline Formalism
We construct detour complexes from the BRST quantization of worldline
diffeomorphism invariant systems. This yields a method to efficiently extract
physical quantum field theories from particle models with first class
constraint algebras. As an example, we show how to obtain the Maxwell detour
complex by gauging N=2 supersymmetric quantum mechanics in curved space. Then
we concentrate on first class algebras belonging to a class of recently
introduced orthosymplectic quantum mechanical models and give generating
functions for detour complexes describing higher spins of arbitrary symmetry
types. The first quantized approach facilitates quantum calculations and we
employ it to compute the number of physical degrees of freedom associated to
the second quantized, field theoretical actions.Comment: 1+35 pages, 1 figure; typos corrected and references added, published
versio
Aharonov-Casher effect for spin one particles in a noncommutative space
In this work the Aharonov-Casher (AC) phase is calculated for spin one
particles in a noncommutative space. The AC phase has previously been
calculated from the Dirac equation in a noncommutative space using a gauge-like
technique [17]. In the spin-one, we use kemmer equation to calculate the phase
in a similar manner. It is shown that the holonomy receives non-trivial
kinematical corrections. By comparing the new result with the already known
spin 1/2 case, one may conjecture a generalized formula for the corrections to
holonomy for higher spins.Comment: 9 page
Schr\"odinger Manifolds
This article propounds, in the wake of influential work of Fefferman and
Graham about Poincar\'e extensions of conformal structures, a definition of a
(Poincar\'e-)Schr\"odinger manifold whose boundary is endowed with a conformal
Bargmann structure above a non-relativistic Newton-Cartan spacetime. Examples
of such manifolds are worked out in terms of homogeneous spaces of the
Schr\"odinger group in any spatial dimension, and their global topology is
carefully analyzed. These archetypes of Schr\"odinger manifolds carry a Lorentz
structure together with a preferred null Killing vector field; they are shown
to admit the Schr\"odinger group as their maximal group of isometries. The
relationship to similar objects arising in the non-relativisitc AdS/CFT
correspondence is discussed and clarified.Comment: 42 pages, 1 figure, published version: J. Phys. A: Math. Theor. 45
(2012) 395203 (24pp
Paul trapping of radioactive 6He+ions and direct observation of their beta-decay
We demonstrate that abundant quantities of short-lived beta unstable ions can
be trapped in a novel transparent Paul trap and that their decay products can
directly be detected in coincidence. Low energy 6He+ (807 ms half-life) ions
were extracted from the SPIRAL source at GANIL, then decelerated, cooled and
bunched by means of the buffer gas cooling technique. More than 10^8 ions have
been stored over a measuring period of six days and about 10^5 decay
coincidences between the beta particles and the 6Li^{++} recoiling ions have
been recorded. The technique can be extended to other short-lived species,
opening new possibilities for trap assisted decay experiments.Comment: 4 pages, 4 figures, submitted to Phys.Rev.Let
Landau Analog Levels for Dipoles in the Noncommutative Space and Phase Space
In the present contribution we investigate the Landau analog energy
quantization for neutral particles, that possesses a nonzero permanent magnetic
and electric dipole moments, in the presence of an homogeneous electric and
magnetic external fields in the context of the noncommutative quantum
mechanics. Also, we analyze the Landau--Aharonov--Casher and
Landau--He--McKellar--Wilkens quantization due to noncommutative quantum
dynamics of magnetic and electric dipoles in the presence of an external
electric and magnetic fields and the energy spectrum and the eigenfunctions are
obtained. Furthermore, we have analyzed Landau quantization analogs in the
noncommutative phase space, and we obtain also the energy spectrum and the
eigenfunctions in this context.Comment: 20 pages, references adde
Symmetries and currents of the ideal and unitary Fermi gases
The maximal algebra of symmetries of the free single-particle Schroedinger
equation is determined and its relevance for the holographic duality in
non-relativistic Fermi systems is investigated. This algebra of symmetries is
an infinite dimensional extension of the Schroedinger algebra, it is isomorphic
to the Weyl algebra of quantum observables, and it may be interpreted as a
non-relativistic higher-spin algebra. The associated infinite collection of
Noether currents bilinear in the fermions are derived from their relativistic
counterparts via a light-like dimensional reduction. The minimal coupling of
these currents to background sources is rewritten in a compact way by making
use of Weyl quantisation. Pushing forward the similarities with the holographic
correspondence between the minimal higher-spin gravity and the critical O(N)
model, a putative bulk dual of the unitary and the ideal Fermi gases is
discussed.Comment: 67 pages, 2 figures; references added, minor improvements in the
presentation, version accepted for publication in JHE
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