819 research outputs found
The Abelian/Nonabelian Correspondence and Frobenius Manifolds
We propose an approach via Frobenius manifolds to the study (began in
math.AG/0407254) of the relation between rational Gromov-Witten invariants of
nonabelian quotients X//G and those of the corresponding ``abelianized''
quotients X//T, for T a maximal torus in G. The ensuing conjecture expresses
the Gromov-Witten potential of X//G in terms of the potential of X//T. We prove
this conjecture when the nonabelian quotients are partial flag manifolds.Comment: 35 pages, no figure
Growth model with restricted surface relaxation
We simulate a growth model with restricted surface relaxation process in d=1
and d=2, where d is the dimensionality of a flat substrate. In this model, each
particle can relax on the surface to a local minimum, as the Edwards-Wilkinson
linear model, but only within a distance s. If the local minimum is out from
this distance, the particle evaporates through a refuse mechanism similar to
the Kim-Kosterlitz nonlinear model. In d=1, the growth exponent beta, measured
from the temporal behavior of roughness, indicates that in the coarse-grained
limit, the linear term of the Kardar-Parisi-Zhang equation dominates in short
times (low-roughness) and, in asymptotic times, the nonlinear term prevails.
The crossover between linear and nonlinear behaviors occurs in a characteristic
time t_c which only depends on the magnitude of the parameter s, related to the
nonlinear term. In d=2, we find indications of a similar crossover, that is,
logarithmic temporal behavior of roughness in short times and power law
behavior in asymptotic times
Localization of major ephedra alkaloids in whole aerial parts of Ephedrae Herba using direct analysis in real time-time of flight-mass spectrometry
Plant science
North Korean CO emissions reconstruction using DMZ ground observations, TROPOMI space-borne data, and the CMAQ air quality model
Emission uncertainty in North Korea can act as an obstacle when developing air pollution management plans in the country and neighboring countries when the transboundary transport of air pollutants is considered. This study introduces a novel approach for adjusting and reallocating North Korean CO emissions, aiming to complement the limited observational and emissions data on the country's air pollutants. We utilized ground observations from demilitarized zone (DMZ) and vertical column density (VCD) data from a TROPOspheric Monitoring Instrument (TROPOMI), which were combined with the Community Multi-Scale Air Quality (CMAQ) chemistry transport model simulations. The Clean Air Support System (CAPSS) and Satellite Integrated Joint Monitoring of Air Quality (SIJAQ) emissions inventories served as the basis for our initial simulations. A two-step procedure was proposed to adjust both the emission intensity and the spatial distribution of emissions. First, air quality simulations were conducted to explore model sensitivity to changes in North Korean CO emissions with respect to ground concentrations. DMZ observations then constrained these simulations to estimate corresponding emission intensity. Second, the spatial structure of North Korean CO emission sources was reconstructed with the help of TROPOMI CO VCD distributions. Our two-step hybrid method outperformed individual emissions adjustment and spatial reallocation based solely on surface or satellite observations. Validation using ground observations from the Chinese Dandong site near the China-North Korea border revealed significantly improved model simulations when applying the updated CO emissions. The adjusted CO emissions were 10.9 times higher than those derived from the bottom-up emissions used in this study, highlighting the lack of information on North Korean pollutants and emission sources. This approach offers an efficient and practical solution for identifying potential missing emission sources when there is limited on-site information about air quality on emissions
Violation of the Mott-Ioffe-Regel Limit: High-temperature Resistivity of Itinerant Magnets Srn+1RunO3n+1 (n=2,3,infinity) and CaRuO3
Srn+1RunO3n+1 represents a class of layered materials whose physical
properties are a strong function of the number of Ru-O layers per unit cell, n.
This series includes the p-wave superconductor Sr2RuO4 (n=1), enhanced
paramagnetic Sr3Ru2O7 (n=2), nearly ferromagnetic Sr4Ru3O10 (n=3) and itinerant
ferromagnetic SrRuO3 (n=infinity). In spite of a wide spectrum of physical
phenomena, this series of materials along with paramagnetic CaRuO3 shares two
major characteristics, namely, robust Fermi liquid behavior at low temperatures
and anomalous transport behavior featured by linear temperature dependence of
resistivity at high temperature where electron wavepackets are no longer
clearly defined. There is no crossover separating such two fundamentally
different states. In this paper, we report results of our study that
systematically addresses anisotropy and temperature dependence of basal-plane
and c-axis resistivity as a function of n for the entire Srn+1RunO3n+1 series
and CaRuO3 and for a wide temperature range of 1.7 K<T<900 K. It is found that
the anomalous transport behavior correlates with magnetic susceptibility and
becomes stronger with decreasing dimensionality. Implications of these results
are discussed
Evidence for non-Dzyaloshinskii–Moriya ferromagnetism in epitaxial BiFeO₃ films
BiFeO₃ films have been prepared by dc magnetron sputtering on LaAlO₃ (001) single-crystalline substrate. X-ray diffraction analysis and high-resolution electron-microscopy study reveal that the films have a highly coriented orthorhombic crystal structure. It was found that the magnetic properties of the BiFeO₃ films are typical for the ensemble of interacting superparamagnetic clusters rather than for the Dzyaloshinskii–Moriya weak ferromagnet. Appearance of the extrinsic nanoscale superparamagnetic clusters is explained by the oxygen deficiency in certain regions of the film, where the ferromagnetic ordering is realized through the double-exchange mechanism by Zener
Critical behavior of the two-dimensional N-component Landau-Ginzburg Hamiltonian with cubic anisotropy
We study the two-dimensional N-component Landau-Ginzburg Hamiltonian with
cubic anisotropy. We compute and analyze the fixed-dimension perturbative
expansion of the renormalization-group functions to four loops. The relations
of these models with N-color Ashkin-Teller models, discrete cubic models,
planar model with fourth order anisotropy, and structural phase transition in
adsorbed monolayers are discussed. Our results for N=2 (XY model with cubic
anisotropy) are compatible with the existence of a line of fixed points joining
the Ising and the O(2) fixed points. Along this line the exponent has
the constant value 1/4, while the exponent runs in a continuous and
monotonic way from 1 to (from Ising to O(2)). For N\geq 3 we find a
cubic fixed point in the region , which is marginally stable or
unstable according to the sign of the perturbation. For the physical relevant
case of N=3 we find the exponents and at the cubic
transition.Comment: 14 pages, 9 figure
Latex metabolome of Euphorbia species: geographical and inter-species variation and its proposed role in plant defense against herbivores and pathogens
Plant science
Search for DCC in 158A GeV Pb+Pb Collisions
A detailed analysis of the phase space distributions of charged particles and
photons have been carried out using two independent methods. The results
indicate the presence of nonstatistical fluctuations in localized regions of
phase space.Comment: Talk at the PANIC99 Conference, June 9-16, 199
Present Status and Future of DCC Analysis
Disoriented Chiral Condensates (DCC) have been predicted to form in high
energy heavy ion collisions where the approximate chiral symmetry of QCD has
been restored. This leads to large imbalances in the production of charged to
neutral pions. Sophisticated analysis methods are being developed to
disentangle DCC events out of the large background of events with
conventionally produced particles. We present a short review of current
analysis methods and future prospects.Comment: 12 pages, 5 figures. Invited talk presented at the 13th International
Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 97),
Tsukuba, Japan, 1-5 Dec 199
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