574 research outputs found
Strong Southward Transport Events Due to Typhoons in the Taiwan Strait
Transport through the Taiwan Strait under the influence of five typhoons was investigated using both buoy observations and numerical model simulations during the period of 27 August to 5 October 2005. The results show that the effects of typhoons on the Taiwan Strait and its adjacent sea area caused strong southward transport events in the Taiwan Strait, which changed the direction of the Taiwan Strait northward transport temporarily. Typhoon-generated local wind stress and/or along-strait water level gradient were the direct driving factors in these southward transport events. The numerical results show that the Coriolis force made a negative contribution to these events and the contribution of the along-strait momentum gradient was insignificant
Laser-driven lepton polarization in the quantum radiation-dominated reflection regime
Generation of ultrarelativistic polarized leptons during interaction of an
ultrarelativistic electron beam with a counterpropagating ultraintense laser
pulse is investigated in the quantum radiation-dominated domain. While the
symmetry of the laser field tends to average the radiative polarization of
leptons to zero, we demonstrate the feasibility of sizable radiative
polarization through breaking the symmetry of the process in the reflection
regime. After the reflection, the off-axis particles escape the tightly focused
beam with polarization correlated to the emission angle, while the particles at
the beam center are more likely to be captured in the laser field with
unmatched polarization and kinetic motion. Meanwhile, polarization along the
electric field emerges due to the spin rotation in the transverse plane via
precession. In this way, the combined effects of radiative polarization, spin
precession and the laser field focusing are shaping the angle-dependent
polarization for outgoing leptons. Our spin-resolved Monte Carlo simulations
demonstrate an angle-dependent polarization degree up to for both
electrons and positrons, with a yield of one pair per seed electron. It
provides a new approach for producing polarized high density electron and
positron jets at ultraintense laser facilities
A Complete Set of Local Invariants for a Family of Multipartite Mixed States
We study the equivalence of quantum states under local unitary
transformations by using the singular value decomposition. A complete set of
invariants under local unitary transformations is presented for several classes
of tripartite mixed states in KxMxN composite systems. Two density matrices in
the same class are equivalent under local unitary transformations if and only
if all these invariants have equal values for these density matrices.Comment: 10 page
Virologic and clinical characteristics of HBV genotypes/subgenotypes in 487 Chinese pediatric patients with CHB
<p>Abstract</p> <p>Background</p> <p>The association of hepatitis B virus (HBV) genotypes/subgenotypes with clinical characteristics is increasingly recognized. However, the virologic and clinical features of HBV genotypes/subgenotypes in pediatric patients remain largely unknown.</p> <p>Methods</p> <p>Four hundred and eighty-seven pediatric inpatients with CHB were investigated, including 217 nucleos(t)ide analog-experienced patients. HBV genotypes/subgenotypes and reverse transcriptase (RT) mutations were determined by direct sequencing. The stage of fibrosis and degree of inflammatory activity were evaluated by the Metavir score system.</p> <p>Results</p> <p>Among 487 enrolled pediatric patients, HBV genotype C2 and B2 were the most two prevalent (73.7% and 21.1%). Comparing with HBV/B2 infected patients, no significant difference was observed in the incidence rate and mutant patterns of lamivudine- or adefovir-resistant mutations in HBV/C2 infected patients (<it>P </it>> 0.05). Importantly, we found that the degree of hepatic inflammation degree, fibrosis stage and ALT level were significantly higher in HBV/C2-infected HBeAg positive patients than it was in HBV/B2-infected ones.</p> <p>Conclusions</p> <p>The pediatric patients with HBV/C2 infection might be more susceptible to develop severe liver pathogenesis.</p
Computational identification of condition-specific miRNA targets based on gene expression profiles and sequence information
<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) are small and noncoding RNAs that play important roles in various biological processes. They regulate target mRNAs post-transcriptionally through complementary base pairing. Since the changes of miRNAs affect the expression of target genes, the expression levels of target genes in specific biological processes could be different from those of non-target genes. Here we demonstrate that gene expression profiles contain useful information in separating miRNA targets from non-targets.</p> <p>Results</p> <p>The gene expression profiles related to various developmental processes and stresses, as well as the sequences of miRNAs and mRNAs in <it>Arabidopsis</it>, were used to determine whether a given gene is a miRNA target. It is based on the model combining the support vector machine (SVM) classifier and the scoring method based on complementary base pairing between miRNAs and mRNAs. The proposed model yielded low false positive rate and retrieved condition-specific candidate targets through a genome-wide screening.</p> <p>Conclusion</p> <p>Our approach provides a novel framework into screening target genes by considering the gene regulation of miRNAs. It can be broadly applied to identify condition-specific targets computationally by embedding information of gene expression profiles.</p
All-Optical Generation of Surface Plasmons in Graphene
27 pages, 12 figures, includes supplementary materialarXiv is an e-print service in the fields of physics, mathematics, computer science, quantitative biology, quantitative finance and statistics.Here we present an all-optical plasmon coupling scheme, utilising the intrinsic nonlinear optical response of graphene. We demonstrate coupling of free-space, visible light pulses to the surface plasmons in a planar, un-patterned graphene sheet by using nonlinear wave mixing to match both the wavevector and energy of the surface wave. By carefully controlling the phase-matching conditions, we show that one can excite surface plasmons with a defined wavevector and direction across a large frequency range, with an estimated photon efficiency in our experiments approaching
Phosphorene: Fabrication, Properties and Applications
Phosphorene, the single- or few-layer form of black phosphorus, was recently
rediscovered as a twodimensional layered material holding great promise for
applications in electronics and optoelectronics. Research into its fundamental
properties and device applications has since seen exponential growth. In this
Perspective, we review recent progress in phosphorene research, touching upon
topics on fabrication, properties, and applications; we also discuss challenges
and future research directions. We highlight the intrinsically anisotropic
electronic, transport, optoelectronic, thermoelectric, and mechanical
properties of phosphorene resulting from its puckered structure in contrast to
those of graphene and transition-metal dichalcogenides. The facile fabrication
and novel properties of phosphorene have inspired design and demonstration of
new nanodevices; however, further progress hinges on resolutions to technical
obstructions like surface degradation effects and non-scalable fabrication
techniques. We also briefly describe the latest developments of more
sophisticated design concepts and implementation schemes that address some of
the challenges in phosphorene research. It is expected that this fascinating
material will continue to offer tremendous opportunities for research and
development for the foreseeable future.Comment: invited perspective for JPC
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