460 research outputs found
Radiative transitions in charmonium from twisted mass lattice QCD
We present a study for charmonium radiative transitions:
, and
using twisted mass lattice QCD gauge
configurations. The single-quark vector form factors for and
are also determined. The simulation is performed at a lattice
spacing of fm and the lattice size is . After
extrapolation of lattice data at nonzero to 0, we compare our results
with previous quenched lattice results and the available experimental values.Comment: typeset with revtex, 15 pages, 11 figures, 4 table
De novo intestine-specific transcriptome of the brown planthopper Nilaparvata lugens revealed potential functions in digestion, detoxification and immune response
AbstractThe brown planthopper (Nilaparvata lugens, BPH) is the most serious rice plant pests in Asia. In this study, we performed transcriptome-wide analysis on BPH intestine. We obtained more than 26 million sequencing reads that were then assembled into 53,553 unigenes with a mean size of 388bp. Based on similarity search with the nucleotide sequences available at NCBI, BPH intestine-specific transcriptome analysis identified 21,405 sequences. Assembled sequences were annotated with gene description, gene ontology and clusters of orthologous group terms. The digestion-, defense- and xenobiotic metabolism-related genes were abundantly detected in the transcripts from BPH intestine. Many novel genes including 33 digestion-related genes, 25 immune responsive genes and 27 detoxification-related genes are first reported here. We investigated the gene expression patterns at the transcript levels in different tissues by quantitative real-time PCR analysis, which revealed that some genes had intestine-specific expression, implicating their potential significance for BPH management
Structure and superconductivity of Mg(B1-xCx)2 compounds
In this paper, we reported the structural properties and superconductivity of
Mg(B1-xCx)2 compounds. Powder x-ray diffraction results indicate that the
samples crystallize in a hexagonal AlB2-type structure. Due to the chemical
activity of Mg powders, a small amount of MgO impurity phase was detected by
x-ray diffraction. The lattice parameters decrease slightly with increasing
carbon content. Magnetization measurements indicate the non-stoichiometry of
MgB2 has no influence on the superconducting transition temperature and the
transition temperature width. The addition of carbon results in a decrease of
Tc and an increase in the superconducting transition width, implying the loss
of superconductivity.Comment: PDF files, 5 pages,3 figures, Accepted by Chinese Physics on Feb. 26,
2001(in press
Genome sequence and organization of a nucleopolyhedrovirus that infects the tea looper caterpillar, Ectropis obliqua
AbstractThe complete nucleotide sequence of Ectropis obliqua nucleopolyhedrovirus (EcobNPV), which infects the tea looper caterpillar, was determined and analyzed. The double stranded circular genome is composed of 131,204Â bp and is 37.6% G+C rich. The analysis predicted 126 putative, minimally overlapping open reading frames (ORFs) with 150 or more nucleotides that together compose 89.8% of the genome. The remaining 10.2% constitute non-coding and three homologous regions. Comparison with previously sequenced baculoviruses indicated that three ORFs were unique to EcobNPV, while the remaining 123 ORFs shared identity with other baculovirus genes. In addition to two bro homologues, three other repeat ORFs, including dbp, p26, and odv-e66, were identified. Phylogenetic analysis indicated that each member of the paired ORFs was acquired independently. Gene parity plot analysis and percent identity of gene homologues suggested that EcobNPV is a Group II NPV, although its genomic organization was highly distinct
De novo characterization of a whitefly transcriptome and analysis of its gene expression during development
<p>Abstract</p> <p>Background</p> <p>Whitefly (<it>Bemisia tabaci</it>) causes extensive crop damage throughout the world by feeding directly on plants and by vectoring hundreds of species of begomoviruses. Yet little is understood about its genes involved in development, insecticide resistance, host range plasticity and virus transmission.</p> <p>Results</p> <p>To facilitate research on whitefly, we present a method for <it>de novo </it>assembly of whitefly transcriptome using short read sequencing technology (Illumina). In a single run, we produced more than 43 million sequencing reads. These reads were assembled into 168,900 unique sequences (mean size = 266 bp) which represent more than 10-fold of all the whitefly sequences deposited in the GenBank (as of March 2010). Based on similarity search with known proteins, these analyses identified 27,290 sequences with a cut-off E-value above 10<sup>-5</sup>. Assembled sequences were annotated with gene descriptions, gene ontology and clusters of orthologous group terms. In addition, we investigated the transcriptome changes during whitefly development using a tag-based digital gene expression (DGE) system. We obtained a sequencing depth of over 2.5 million tags per sample and identified a large number of genes associated with specific developmental stages and insecticide resistance.</p> <p>Conclusion</p> <p>Our data provides the most comprehensive sequence resource available for whitefly study and demonstrates that the Illumina sequencing allows <it>de novo </it>transcriptome assembly and gene expression analysis in a species lacking genome information. We anticipate that next generation sequencing technologies hold great potential for the study of the transcriptome in other non-model organisms.</p
(E)-N′-(2-BromoÂbenzylÂidene)-2-fluoroÂbenzohydrazide
The title compound, C14H10BrFN2O, adopts an E geometry about the C=N bond. The dihedral angle between the mean planes of the two benzene rings is 81.5 (6)°. In the crystal, molÂecules are linked through interÂmolecular N—H⋯O hydrogen bonds, forming chains running along the b axis
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Selection and environmental adaptation along a path to speciation in the Tibetan frog Nanorana parkeri.
Tibetan frogs, Nanorana parkeri, are differentiated genetically but not morphologically along geographical and elevational gradients in a challenging environment, presenting a unique opportunity to investigate processes leading to speciation. Analyses of whole genomes of 63 frogs reveal population structuring and historical demography, characterized by highly restricted gene flow in a narrow geographic zone lying between matrilines West (W) and East (E). A population found only along a single tributary of the Yalu Zangbu River has the mitogenome only of E, whereas nuclear genes of W comprise 89-95% of the nuclear genome. Selection accounts for 579 broadly scattered, highly divergent regions (HDRs) of the genome, which involve 365 genes. These genes fall into 51 gene ontology (GO) functional classes, 14 of which are likely to be important in driving reproductive isolation. GO enrichment analyses of E reveal many overrepresented functional categories associated with adaptation to high elevations, including blood circulation, response to hypoxia, and UV radiation. Four genes, including DNAJC8 in the brain, TNNC1 and ADORA1 in the heart, and LAMB3 in the lung, differ in levels of expression between low- and high-elevation populations. High-altitude adaptation plays an important role in maintaining and driving continuing divergence and reproductive isolation. Use of total genomes enabled recognition of selection and adaptation in and between populations, as well as documentation of evolution along a stepped cline toward speciation
The mouse and ferret models for studying the novel avian-origin human influenza A (H7N9) virus.
BackgroundThe current study was conducted to establish animal models (including mouse and ferret) for the novel avian-origin H7N9 influenza virus.FindingsA/Anhui/1/2013 (H7N9) virus was administered by intranasal instillation to groups of mice and ferrets, and animals developed typical clinical signs including body weight loss (mice and ferrets), ruffled fur (mice), sneezing (ferrets), and death (mice). Peak virus shedding from respiratory tract was observed on 2 days post inoculation (d.p.i.) for mice and 3-5 d.p.i. for ferrets. Virus could also be detected in brain, liver, spleen, kidney, and intestine from inoculated mice, and in heart, liver, and olfactory bulb from inoculated ferrets. The inoculation of H7N9 could elicit seroconversion titers up to 1280 in ferrets and 160 in mice. Leukopenia, significantly reduced lymphocytes but increased neutrophils were also observed in mouse and ferret models.ConclusionsThe mouse and ferret model enables detailed studies of the pathogenesis of this illness and lay the foundation for drug or vaccine evaluation
A Novel Concept of Ribless Synchronous Reluctance Motor for Enhanced Torque Capability
The rotor structure of synchronous reluctance machines (SynRel) is conventionally retained mechanically by iron ribs. In this paper a novel structure for high speed synchronous reluctance rotor is presented. The novelty of this work is the proof of a concept of SynRel machine without iron ribs. Structurally, the rotor iron lamination segments are embedded in an adhesive resin material with high temperature resistance and mechanical strength. Three four-pole SynRel machines have been designed with the target of improving motor torque, and compared for different ribs configuration. It has been shown that the proposed motor performs enhanced torque, power factor and efficiency with respect to conventional SynRel with iron ribs. An extensive sensitivity analysis of the ribless rotor geometry is carried out, followed by both mechanical analysis and experimental over speed test to guarantee its robustness above the operating speed range. The manufacturing procedure of this novel rotor is introduced. Finally, the experimental results on both SynRel prototypes are presented, showing the increase in torque, power factor and efficiency of the proposed solution. This work is a first step towards the definition of a viable and novel solution of SynRel machines with improved performance
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