420 research outputs found
The Fukui matrix : a simple approach to the analysis of the Fukui function and its positive character
The Fukui matrix is introduced as the derivative of the one-electron reduced density matrix with respect to a change in the number of electrons under constant external potential. The Fukui matrix extends the Fukui function concept: the diagonal of the Fukui matrix is the Fukui function. Diagonalizing the Fukui matrix gives a set of eigenvectors, the Fukui orbitals, and accompanying eigenvalues. At the level of theory used, there is always one dominant eigenvector, with an eigenvalue equal to 1. The remaining eigenvalues are either zero or come in pairs with eigenvalues of the same magnitude but opposite sign. Analysis of the frontier molecular orbital coefficient in the eigenvector with eigenvalue 1 gives information on the quality of the frontier molecular orbital picture. The occurrence of negative Fukui functions can be easily interpreted in terms of the nodal character of the dominant eigenvector versus the characteristics of the remaining eigenvectors and eigenvalues
Draft Genome Sequence of the Symbiotic Frankia sp. strain B2 isolated from root nodules of Casuarina cunninghamiana found in Algeria
Frankia sp. strain B2 was isolated from Casuarina cunninghamiana nodules. Here, we report the 5.3-Mbp draft genome sequence of Frankia sp. strain B2 with a G+C content of 70.1 % and 4,663 candidate protein-encoding genes. Analysis of the genome revealed the presence of high numbers of secondary metabolic biosynthetic gene clusters
Atomic diffraction from nanostructured optical potentials
We develop a versatile theoretical approach to the study of cold-atom
diffractive scattering from light-field gratings by combining calculations of
the optical near-field, generated by evanescent waves close to the surface of
periodic nanostructured arrays, together with advanced atom wavepacket
propagation on this optical potential.Comment: 8 figures, 10 pages, submitted to Phys. Rev.
Functional genomics in chickens:development of integrated-systems microarrays for transcriptional profiling and discovery of regulatory pathways
The genetic networks that govern the differentiation and growth of major tissues
of economic importance in the chicken are largely unknown. Under a functional
genomics project, our consortium has generated 30 609 expressed sequence
tags (ESTs) and developed several chicken DNA microarrays, which represent the
Chicken Metabolic/Somatic (10 K) and Neuroendocrine/Reproductive (8 K) Systems
(http://udgenome.ags.udel.edu/cogburn/). One of the major challenges facing functional
genomics is the development of mathematical models to reconstruct functional
gene networks and regulatory pathways from vast volumes of microarray data. In initial
studies with liver-specific microarrays (3.1 K), we have examined gene expression
profiles in liver during the peri-hatch transition and during a strong metabolic perturbation—fasting
and re-feeding—in divergently selected broiler chickens (fast vs. slow-growth lines).
The expression of many genes controlling metabolic pathways
is dramatically altered by these perturbations. Our analysis has revealed a
large number of clusters of functionally related genes (mainly metabolic enzymes
and transcription factors) that control major metabolic pathways. Currently, we are
conducting transcriptional profiling studies of multiple tissues during development of
two sets of divergently selected broiler chickens (fast vs. slow growing and fat vs. lean
lines). Transcriptional profiling across multiple tissues should permit construction of
a detailed genetic blueprint that illustrates the developmental events and hierarchy
of genes that govern growth and development of chickens. This review will briefly
describe the recent acquisition of chicken genomic resources (ESTs and microarrays)
and our consortium's efforts to help launch the new era of functional genomics in
the chicken
Design of smart garments for sports and rehabilitation
Physical exercise has proved benefits for general health [1] and can reduce the number
of sports injuries to one third [2]. However, an athlete that has been injured during sports practice
may omit this out of fear of discrimination, and worsen the injury in the weight room, during
strength training [5]. Monitoring physiological status of an athlete or rehabilitation patients
during training may thus help the person to get an earlier intervention, preventing injuries from
getting worse. With this in mind, we propose a set of compression garments – shirt and leggings
– with textile sensors to continually monitor heart and muscle activity, breathing rate and
temperature. This paper reports the design of the garments and production of the shirt, which
comprised a 3-lead ECG system, sEMG (Surface Electromiography) electrodes and a breathing
sensor. The ECG (Electrocardiography) system was tested and presented some good results, in
particular for very even movements, but the system still needs to be improved, in order to get a
better signal, when it comes to movements with a considerable amplitude.This work is financed by Project “Deus ex Machina”, NORTE-01-0145-FEDER-000026, funded by CCDRN, through Sistema de Apoio à Investigação Cientifica e Tecnológica (Projetos Estruturados I&D&I) of Programa Operacional Regional do Norte, from Portugal 2020 and by FEDER funds through the Competitivity Factors Operational Programme - COMPETE and by national funds through FCT – Foundation for Science and Technology within the scope of the project POCI-01-0145-FEDER-007136.info:eu-repo/semantics/publishedVersio
Superradiance from an ultrathin film of three-level V-type atoms: Interplay between splitting, quantum coherence and local-field effects
We carry out a theoretical study of the collective spontaneous emission
(superradiance) from an ultrathin film comprised of three-level atoms with
-configuration of the operating transitions. As the thickness of the system
is small compared to the emission wavelength inside the film, the local-field
correction to the averaged Maxwell field is relevant. We show that the
interplay between the low-frequency quantum coherence within the subspace of
the upper doublet states and the local-field correction may drastically affect
the branching ratio of the operating transitions. This effect may be used for
controlling the emission process by varying the doublet splitting and the
amount of low-frequency coherence.Comment: 15 pages, 5 figure
Quail Genomics: a knowledgebase for Northern bobwhite
<p>Abstract</p> <p>Background</p> <p>The Quail Genomics knowledgebase (<url>http://www.quailgenomics.info</url>) has been initiated to share and develop functional genomic data for Northern bobwhite (<it>Colinus virginianus</it>). This web-based platform has been designed to allow researchers to perform analysis and curate genomic information for this non-model species that has little supporting information in GenBank.</p> <p>Description</p> <p>A multi-tissue, normalized cDNA library generated for Northern bobwhite was sequenced using 454 Life Sciences next generation sequencing. The Quail Genomics knowledgebase represents the 478,142 raw ESTs generated from the sequencing effort in addition to assembled nucleotide and protein sequences including 21,980 unigenes annotated with meta-data. A normalized MySQL relational database was established to provide comprehensive search parameters where meta-data can be retrieved using functional and structural information annotation such as gene name, pathways and protein domain. Additionally, blast hit cutoff levels and microarray expression data are available for batch searches. A Gene Ontology (GO) browser from Amigo is locally hosted providing 8,825 unigenes that are putative orthologs to chicken genes. In an effort to address over abundance of Northern bobwhite unigenes (71,384) caused by non-overlapping contigs and singletons, we have built a pipeline that generates scaffolds/supercontigs by aligning partial sequence fragments against the indexed protein database of chicken to build longer sequences that can be visualized in a web browser. </p> <p>Conclusion</p> <p>Our effort provides a central repository for storage and a platform for functional interrogation of the Northern bobwhite sequences providing comprehensive GO annotations, meta-data and a scaffold building pipeline. The Quail Genomics knowledgebase will be integrated with Japanese quail (<it>Coturnix coturnix</it>) data in future builds and incorporate a broader platform for these avian species. </p
Melting of tantalum at high pressure determined by angle dispersive x-ray diffraction in a double-sided laser-heated diamond-anvil cell
The high pressure and high temperature phase diagram of Ta has been studied
in a laser-heated diamond-anvil cell (DAC) using x-ray diffraction measurements
up to 52 GPa and 3800 K. The melting was observed at nine different pressures,
being the melting temperature in good agreement with previous laser-heated DAC
experiments, but in contradiction with several theoretical calculations and
previous piston-cylinder apparatus experiments. A small slope for the melting
curve of Ta is estimated (dTm/dP = 24 K/GPa at 1 bar) and a possible
explanation for this behaviour is given. Finally, a P-V-T equation of states is
obtained, being the temperature dependence of the thermal expansion coefficient
and the bulk modulus estimated.Comment: 31 pages, 8 figures, to appear in J.Phys.:Cond.Matte
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