11,453 research outputs found
Coupled optical interface modes in a Fibonacci dielectric superlattice
The coupled optical interface modes in a Fibonacci dielectric superlattice are studied. In the dielectric continuum approximation, the dispersion relation is found to have two bands of dual triadic Cantor structures, each being nonuniform scaling. For most of the eigenfrequencies, the amplitude profiles of electrostatic potential in this quasiperiodic structure are critical. Moreover, an invariant is analytically derived and is used to describe the general features of the frequency spectra and potential profiles.published_or_final_versio
Quantum waveguide theory of serial stub structures
The electronic behaviors in quantum wires with serial stubs are studied. A general theory of quantum waveguide based on transfer matrix method is developed and is used to treat periodic stub structures, serial stub structures with a defect stub, and Fibonacci stub structures. A number of interesting physical properties in connection with electronic transmission, energy spectra, and charge density distributions in these structures, are found theoretically. In particular, we find that whether there are periodicity and symmetry in the transmission and energy spectra depends on the commensurability of the length parameters. If one length ratio is incommensurate, then the transmission and energy spectra do not exhibit periodicity and symmetry even for periodic stub structures. In particular, the quasiperiodic behaviors are shown in Fibonacci stub structures proposed by us whenever the length parameters are commensurate. The experimental relevance is also addressed briefly. © 1999 American Institute of Physics.published_or_final_versio
Hepatitis B virus X gene in the development of hepatocellular carcinoma
Key Messages 1. Deletion of the 3’end of the hepatitis B virus X gene (HBx) was frequently detected in clinical hepatocellular carcinoma (HCC) samples. 2. In vivo animal tumour xenograft experiments demonstrated the tumourigenic ability of the C-terminal truncated HBx. 3. cDNA microarray study suggested that the C-terminal truncated HBx played a critical role in the HCC development via activation of cell proliferation and inhibition of apoptosis.published_or_final_versio
Persistent currents in mesoscopic Fibonacci rings
In the framework of a tight-binding model, we study energy spectra and persistent currents in mesoscopic Fibonacci rings threaded by a magnetic flux. It is found that the flux-dependent electron eigenenergies E(Φ) in mesoscopic Fibonacci rings still form "bands" with respect to the flux Φ, but there is a scaling relation between the total "bandwidth" and the Fibonacci number. When the strength of the one-dimensional quasiperiodic potential increases, the persistent current decreases rapidly. Interestingly, for a generalized mixing model of mesoscopic Fibonacci rings, free-electron-like persistent current may appear if the number of electrons of the system takes a specific value.published_or_final_versio
Hydrodynamics of a 5D Einstein-dilaton black hole solution and the corresponding BPS state
We apply the potential reconstruction approach to generate a series of
asymptotically AdS (aAdS) black hole solutions, with a self-interacting bulk
scalar field. Based on the method, we reproduce the pure AdS solution as a
consistency check and we also generate a simple analytic 5D black hole
solution. We then study various aspects of this solution, such as temperature,
entropy density and conserved charges. Furthermore, we study the hydrodynamics
of this black hole solution in the framework of fluid/gravity duality, e.g. the
ratio of the shear viscosity to the entropy density. In a degenerate case of
the 5D black hole solution, we find that the c function decreases monotonically
from UV to IR as expected. Finally, we investigate the stability of the
degenerate solution by studying the bosonic functional energy of the gravity
and the Witten-Nester energy . We confirm that the degenerate solution
is a BPS domain wall solution. The corresponding superpotential and the
solution of the killing spinor equation are found explicitly.Comment: V2: 23 pages, no figure, minor changes, typos corrected, new
references and comments added, version accepted by JHE
Microstructures and resistivity of cuprate/manganite bilayer deposited on SrTiO3 substrate
Thin Yba[SUB2]Cu[SUB3]O[SUB7-δ/La[SUB0.67]Ca[SUB0.33]MnO[SUB3] (YBCO/LCMO) films were grown on SrTiO[SUB3](STO)substrates by magnetron sputtering technique. The microstructures of the bilayers were characterized and a standard four-probe technique was applied to measure the resistivity of the samples. The interdiffusions at the YBCO/LCMO and LCMO/STO interfaces formed two transient layers with the thickness of about 3 and 2 nm, respectively. All the bilayers were well textured along the c axis. At low temperature, the superconductivity can only be observed when the thickness of YBCO is more than 25 nm. When the thickness of YBCO is less than 8 nm, the bilayers show only ferromagnetism. The superconductivity and ferromagnetism perhaps coexist in the bilayer with the YBCO thickness of 12.5 nm. These interesting properties are related to the interaction between spin polarized electrons in the manganites and the cooper pairs in the cuprates. © 2003 American Institute of Physics.published_or_final_versio
Changes in BMI before and during economic development and subsequent risk of cardiovascular disease and total mortality: A 35-year follow-up study in China
postprin
Observation of a pairing pseudogap in a two-dimensional Fermi gas
Pairing of fermions is ubiquitous in nature and it is responsible for a large
variety of fascinating phenomena like superconductivity, superfluidity of
He, the anomalous rotation of neutron stars, and the BEC-BCS crossover in
strongly interacting Fermi gases. When confined to two dimensions, interacting
many-body systems bear even more subtle effects, many of which lack
understanding at a fundamental level. Most striking is the, yet unexplained,
effect of high-temperature superconductivity in cuprates, which is intimately
related to the two-dimensional geometry of the crystal structure. In
particular, the questions how many-body pairing is established at high
temperature and whether it precedes superconductivity are crucial to be
answered. Here, we report on the observation of pairing in a harmonically
trapped two-dimensional atomic Fermi gas in the regime of strong coupling. We
perform momentum-resolved photoemission spectroscopy, analogous to ARPES in the
solid state, to measure the spectral function of the gas and we detect a
many-body pairing gap above the superfluid transition temperature. Our
observations mark a significant step in the emulation of layered
two-dimensional strongly correlated superconductors using ultracold atomic
gases
Study of psi(2S) decays to X J/psi
Using J/psi -> mu^+ mu^- decays from a sample of approximately 4 million
psi(2S) events collected with the BESI detector, the branching fractions of
psi(2S) -> eta J/psi, pi^0 pi^0 J/psi, and anything J/psi normalized to that of
psi(2S) -> pi^+ pi^- J/psi are measured. The results are B(psi(2S) -> eta
J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.098 \pm 0.005 \pm 0.010, B(psi(2S) ->
pi^0 pi^0 J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 0.570 \pm 0.009 \pm 0.026, and
B(psi(2S) -> anything J/psi)/B(psi(2S) -> pi^+ pi^- J/psi) = 1.867 \pm 0.026
\pm 0.055.Comment: 13 pages, 8 figure
A new multicompartmental reaction-diffusion modeling method links transient membrane attachment of E. coli MinE to E-ring formation
Many important cellular processes are regulated by reaction-diffusion (RD) of molecules that takes place both in the cytoplasm and on the membrane. To model and analyze such multicompartmental processes, we developed a lattice-based Monte Carlo method, Spatiocyte that supports RD in volume and surface compartments at single molecule resolution. Stochasticity in RD and the excluded volume effect brought by intracellular molecular crowding, both of which can significantly affect RD and thus, cellular processes, are also supported. We verified the method by comparing simulation results of diffusion, irreversible and reversible reactions with the predicted analytical and best available numerical solutions. Moreover, to directly compare the localization patterns of molecules in fluorescence microscopy images with simulation, we devised a visualization method that mimics the microphotography process by showing the trajectory of simulated molecules averaged according to the camera exposure time. In the rod-shaped bacterium _Escherichia coli_, the division site is suppressed at the cell poles by periodic pole-to-pole oscillations of the Min proteins (MinC, MinD and MinE) arising from carefully orchestrated RD in both cytoplasm and membrane compartments. Using Spatiocyte we could model and reproduce the _in vivo_ MinDE localization dynamics by accounting for the established properties of MinE. Our results suggest that the MinE ring, which is essential in preventing polar septation, is largely composed of MinE that is transiently attached to the membrane independently after recruited by MinD. Overall, Spatiocyte allows simulation and visualization of complex spatial and reaction-diffusion mediated cellular processes in volumes and surfaces. As we showed, it can potentially provide mechanistic insights otherwise difficult to obtain experimentally
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