873 research outputs found
Analysis of Gene Coexpression by B-Spline Based CoD Estimation
The gene coexpression study has emerged as a novel holistic approach for microarray data analysis. Different indices have been used in exploring coexpression relationship, but each is associated with certain pitfalls. The Pearson's correlation coefficient, for example, is not capable of uncovering nonlinear pattern and directionality of coexpression. Mutual information can detect nonlinearity but fails to show directionality. The coefficient of determination (CoD) is unique in exploring different patterns of gene coexpression, but so far only applied to discrete data and the conversion of continuous microarray data to the discrete format could lead to information loss. Here, we proposed an effective algorithm, CoexPro, for gene coexpression analysis. The new algorithm is based on B-spline approximation of coexpression between a pair of genes, followed by CoD estimation. The algorithm was justified by simulation studies and by functional semantic similarity analysis. The proposed algorithm is capable of uncovering both linear and a specific class of nonlinear relationships from continuous microarray data. It can also provide suggestions for possible directionality of coexpression to the researchers. The new algorithm presents a novel model for gene coexpression and will be a valuable tool for a variety of gene expression and network studies. The application of the algorithm was demonstrated by an analysis on ligand-receptor coexpression in cancerous and noncancerous cells. The software implementing the algorithm is available upon request to the authors
μ 3-Oxido-hexa-μ 2-pivalato-tris[(methanol-κO)cobalt(III)] chloride
The crystal structure of the title compound, [Co3(C5H9O2)6O(CH4O)3]Cl, consists of trinuclear CoIII complex cations and chloride anions. The CoIII cation has site symmetry m, and is coordinated by four oxygen atoms from four bridging pivalate groups, one central O anion and a methanol oxygen atom, forming a distorted octahedral geometry. The coordinated methanol molecule is located on a crystallographic special position, the C and O atoms being located on the mirror plane. The central O anion lies in the crystallographic position, and acts as a μ
3-O bridge, linking three equivalent CoIII cations and generating the oxo-centered trinuclear CoIII complex. The chloride anion, which acts as the counter-ion, is located on crystallographic position. O—H⋯Cl hydrogen bonding between the Cl anion and hydroxyl group of the coordinated methanol molecule links the molecules into a supramolecular network
Unconventional Superconducting Symmetry in a Checkerboard Antiferromagnet
We use a renormalized mean field theory to study the Gutzwiller projected BCS
states of the extended Hubbard model in the large limit, or the
--- model on a two-dimensional checkerboard lattice. At small
, the frustration due to the diagonal terms of and does not
alter the -wave pairing symmetry, and the negative (positive)
enhances (suppresses) the pairing order parameter. At large , the
ground state has an extended s-wave symmetry. At the intermediate , the
ground state is or -wave with time reversal symmetry broken.Comment: 6 pages, 6 figure
Distributed entanglement induced by dissipative bosonic media
We describe a scheme with analytic result that allows to generate
steady-state entanglement for two atoms over a dissipative bosonic medium. The
resonant coupling between the mediating bosonic mode and cavity modes produces
three collective atomic decay channels. This dissipative dynamics, together
with the unitary process induced by classical microwave fields, drives the two
atoms to the symmetric or asymmetric entangled steady state conditional upon
the choice of the phases of the microwave fields. The effects on the
steady-state entanglement of off-resonance mediating bosonic modes are
analyzed. The entanglement can be obtained with high fidelity regardless of the
initial state and there is a linear relation in the scaling of the fidelity
with the cooperativity parameter. The fidelity is insensitive to the
fluctuation of the Rabi frequencies of the classical driving fields.Comment: to appear in Europhysics Letter
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