330 research outputs found
Defects in the Tri-critical Ising model
We consider two different conformal field theories with central charge
c=7/10. One is the diagonal invariant minimal model in which all fields have
integer spins; the other is the local fermionic theory with superconformal
symmetry in which fields can have half-integer spin. We construct new conformal
(but not topological or factorised) defects in the minimal model. We do this by
first constructing defects in the fermionic model as boundary conditions in a
fermionic theory of central charge c=7/5, using the folding trick as first
proposed by Gang and Yamaguchi. We then acting on these with interface defects
to find the new conformal defects. As part of the construction, we find the
topological defects in the fermionic theory and the interfaces between the
fermionic theory and the minimal model. We also consider the simpler case of
defects in the theory of a single free fermion and interface defects between
the Ising model and a single fermion as a prelude to calculations in the
tri-critical Ising model.Comment: 54 pages, 5 figures, version as accepted for publication with minor
change
The reflection coefficient for minimal model conformal defects from perturbation theory
We consider a class of conformal defects in Virasoro minimal models that have
been defined as fixed points of the renormalisation group and calculate the
leading contribution to the reflection coefficient for these defects. This
requires several structure constants of the operator algebra of the defect
fields, for which we present a derivation in detail. We compare our results
with our recent work on conformal defects in the tricritical Ising model.Comment: 22 pages; v2: minor changes, defect field transformation law
clarified, reference adde
Magnetoresistance characteristics of Fe3Si/CaF2/Fe3Si heterostructures grown on Si(111) by molecular beam epitaxy
AbstractFe3Si/CaF2/Fe3Si magnetic tunnel junctions (MTJs) have been investigated to demonstrate the tunnel magnetoresistance effects. We fabricated Fe3Si(20 nm)/CaF2(2 nm)/Fe3Si(15 nm) heterostructures epitaxially on a Si(111) substrate by molecular beam epitaxy. The current-voltage characteristics for the MTJs measured at room temperature (RT) were well fitted to Simmonsâ equation. The fitting yields the barrier height Ï=2.5Â eV and the barrier thickness d=1.26Â nm. The magnetoresistance ratio for the MTJs were approximately 0.28% under a bias voltage of 20Â mV at RT
Anti-inflammatory sesquiterpenes from Curcuma zedoaria
This is a preprint of an article whose final and definitive form has been published in the NATURAL PRODUCT RESEARCH © 2006 copyright Taylor & Francis; NATURAL PRODUCT RESEARCH is available online at: http://www.informaworld.com/openurl?genre=article&issn=1478-6419&volume=20&issue=7&spage=680ArticleNATURAL PRODUCT RESEARCH. 20(7): 680-685 (2006)journal articl
Synthesis, determination of the absolute configuration of tonkinelin, and inhibitory action with bovine heart mitochondrial complex I
ArticleBIOORGANIC & MEDICINAL CHEMISTRY. 15(8): 3026-3031 (2007)journal articl
An efficient synthesis of procyanidins. Rare earth metal Lewis acid catalyzed equimolar condensation of catechin and epicatechin
ArticleTETRAHEDRON LETTERS. 48(33): 5891-5894 (2007)journal articl
Lattice Boltzmann method for weakly ionized isothermal plasmas
In this paper, a lattice Boltzmann method (LBM) for weakly ionized isothermal plasmas is presented by introducing a rescaling scheme for the Boltzmann transport equation. Without using this rescaling, we found that the nondimensional relaxation time used in the LBM is too large and the LBM does not produce physically realistic results. The developed model was applied to the electrostatic wave problem and the diffusion process of singly ionized helium plasmas with a 1-3% degree of ionization under an electric field. The obtained results agree well with theoretical values.open8
Radiolarian assemblages related to the oceanâice interaction around the East Antarctic coast
The Southern Ocean plays a central role in Earth's climate, ecology, and biogeochemical cycles. Therefore, understanding long-term changes in Southern Ocean water masses in the geologic past is essential for assessing the role of the Southern Ocean in the climate system. Radiolarian fossils are a useful tool to reconstruct the water masses of the Southern Ocean. However, the radiolarian assemblages in the high latitudes of the Southern Ocean (south of the polar front (PF)) are still poorly understood. In this paper, we report the radiolarian assemblages in surface marine sediment and plankton tow samples collected from the high latitudes south of the PF.
In the surface sediments, four factors (named F1âF4) of the radiolarian assemblages were identified using Q-mode factor analysis, which are related to different water masses and hydrological conditions. F1 is related to the surface waters south of the southern boundary (SB) of the Antarctic Circumpolar Current (ACC), which are cooled by melting sea ice and ice sheets. F2 is associated with water masses north of the SB. A comparison with the vertical distribution of the radiolarian assemblages in plankton tow samples indicates that characteristic species are associated with the Circumpolar Deep Water (CDW) and surface waters north of the SB. F3 is associated with modified Circumpolar Deep Water (mCDW). The radiolarian assemblage of F4 does not seem specifically related to any of the water mass here analyzed. However, the species in this assemblage are typically dwells within ice shelf and/or sea ice edge environments. Radiolarian assemblages here identified and associated with water masses, and ice edge environments are useful to reconstruct the environment south of the PF in the geologic past.</p
Hadal water biogeochemistry over the IzuâOgasawara Trench observed with a full-depth CTD-CMS
Full-depth profiles of hydrographic and geochemical
properties at the IzuâOgasawara Trench were observed for the first time
using a CTD-CMS (conductivityâtemperatureâdepth profiler with
carousel multiple sampling) system. Additionally, comparative samplings were
done at the northern Mariana Trench using the same methods. A well-mixed
hydrographic structure below 7000âŻm was observed within the IzuâOgasawara
Trench. Seawater samples collected from this well-mixed hadal layer
exhibited constant concentrations of nitrate, phosphate, silicate, and
nitrous oxide as well as constant nitrogen and oxygen isotopic compositions
of nitrate and nitrous oxide. These results agree well with previous
observations of the IzuâOgasawara hadal waters and deep-sea
water surrounding the IzuâOgasawara Trench. In turn, methane concentrations and
isotopic compositions indicated spatial heterogeneity within the well-mixed
hadal water mass, strongly suggesting a local methane source within the
trench, in addition to the background methane originating from the general
deep-sea bottom water. Sedimentary compound releases, associated with
sediment re-suspensions, are considered to be the most likely mechanism for
generating this significant CH4 anomaly.</p
Striations in electronegative capacitively coupled radio-frequency plasmas: effects of the pressure, voltage, and electrode gap
Capacitively coupled radio-frequency (CCRF) CF_4 plasmas have been found to
exhibit a self-organized striated structure at operating conditions, where the
plasma is strongly electronegative and the ion-ion plasma in the bulk region
(largely composed of CF_3^+ and F^- ions) resonates with the excitation
frequency. In this work we explore the effects of the gas pressure, the RF
voltage, and the electrode gap on this striated structure by Phase Resolved
Optical Emission Spectroscopy and Particle-In-Cell/Monte Carlo Collisions
simulations. The measured electronic excitation patterns at different external
parameters show a good general agreement with the spatio-temporal plots of the
ionization rate obtained from the simulations. For a fixed driving frequency
the minima of the CF_3^+ and F^- ion densities (between the density peaks in
the bulk) are comparable and independent of other external parameters. However,
the ion density maxima generally increase as a function of the pressure or RF
voltage, leading to the enhanced spatial modulation of plasma parameters. The
striation gap (defined as the distance between two ion density peaks) is
approximately inversely proportional to the pressure, while it exhibits a weak
dependence on the RF voltage and the electrode gap. A transition between the
striated and non-striated modes can be observed by changing either the pressure
or the RF voltage; for 13.56 MHz and 18 MHz driving frequencies we present a
phase diagram as a function of the pressure and voltage amplitude parameters.Comment: 32 pages, 18 figures. arXiv admin note: text overlap with
arXiv:1703.0588
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