2,223 research outputs found
Remote sensing and GIS-based analysis of cave development in the Suoimuoi Catchment (Son La - NW Vietnam)
Integration of remotely sensed imagery with ground surveys is a promising method in cave
development studies. In this research a methodology was set up in which a variety of remote
sensing and GIS techniques support cave analysis in the tropical karst area of the Suoimuoi
catchment, NW Vietnam. In order to extract the maximum information from different remotely
sensed data, the hue invariant IHS transformation was applied to integrate Landsat multispectral
channels with the high resolution Landsat 7 ETM panchromatic channel. The resulting
fused image was used, after enhancement, to visually and digitally extract lineaments.
Aerial photos evaluated the extracted lineaments. Based on lineament density indices a fracture
zone favorable for cave development is defined. The distance between caves and faults
was investigated as well as the correspondence between the cave occurrence and the fracture
zone
BIOLOGICAL AMMONIA REMOVAL BY SUBMERGED AERATED FILTER FROM HANOI GROUND WATER
Joint Research on Environmental Science and Technology for the Eart
Minimal SU(5) Resuscitated by Long-Lived Quarks and Leptons
The issue of gauge unification in the (non-supersymmetric) Standard Model is
reinvestigated. It is found that with just an additional fourth generation of
non-sequential and long-lived quarks and leptons, SU(3)xSU(2)xU(1) gauge
couplings converge to a common point of approximately 3.5x10^{15} GeV
(corresponding to a proton lifetime of approximately 10^{34 plus/minus 1}
years). This result is due to the non-negligible- but still perturbative-
contributions of the top and fourth generation Yukawa couplings to the gauge
two-loop beta functions, in contrast with the three generation case where such
a contribution is too small to play an important role in unification.Comment: 12 pages, 2 figure
Dynamics of Binary Mixtures with Ions: Dynamic Structure Factor and Mesophase Formation
Dynamic equations are presented for polar binary mixtures containing ions in
the presence of the preferential solvation. In one-phase states, we calculate
the dynamic structure factor of the composition accounting for the ion motions.
Microphase separation can take place for sufficiently large solvation asymmetry
of the cations and the anions. We show two-dimensional simulation results of
the mesophase formation with an antagonistic salt, where the cations are
hydrophilic and the anions are hydrophobic. The structure factor S(q) in the
resultant mesophase has a sharp peak at an intermediate wave number on the
order of the Debye-Huckel wave number. As the quench depth is increased, the
surface tension nearly vanishes in mesophases due to an electric double layer.Comment: 24 pages, 10 figures, to appear in Journal of Physics: Condensed
Matte
Minimizing efforts in validating crowd answers
In recent years, crowdsourcing has become essential in a wide range of Web applications. One of the biggest challenges of crowdsourcing is the quality of crowd answers as workers have wide-ranging levels of expertise and the worker community may contain faulty workers. Although various techniques for quality control have been proposed, a post-processing phase in which crowd answers are validated is still required. Validation is typically conducted by experts, whose availability is limited and who incur high costs. Therefore, we develop a probabilistic model that helps to identify the most beneficial validation questions in terms of both, improvement of result correctness and detection of faulty workers. Our approach allows us to guide the experts work by collecting input on the most problematic cases, thereby achieving a set of high quality answers even if the expert does not validate the complete answer set. Our comprehensive evaluation using both real-world and synthetic datasets demonstrates that our techniques save up to 50% of expert efforts compared to baseline methods when striving for perfect result correctness. In absolute terms, for most cases, we achieve close to perfect correctness after expert input has been sought for only 20% of the questions
Evidence of early multi-strange hadron freeze-out in high energy nuclear collisions
Recently reported transverse momentum distributions of strange hadrons
produced in Pb(158AGeV) on Pb collisions and corresponding results from the
relativistic quantum molecular dynamics (RQMD) approach are examined. We argue
that the experimental observations favor a scenario in which multi-strange
hadrons are formed and decouple from the system rather early at large energy
densities (around 1 GeV/fm). The systematics of the strange and non-strange
particle spectra indicate that the observed transverse flow develops mainly in
the late hadronic stages of these reactions.Comment: 4 pages, 4 figure
Probing the Rho Spectral Function in Hot and Dense Nuclear Matter by Dileptons
We present a dynamical study of and production in
proton-nucleus and nucleus-nucleus collisions at CERN-SPS energies on the basis
of the covariant transport approach HSD employing a momentum-dependent
-meson spectral function that includes the pion modifications in the
nuclear medium as well as the polarization of the -meson due to resonant
scattering. We find that the experimental data from the CERES and
HELIOS-3 Collaborations can be described equally well as within the dropping
-mass scenario. Whereas corresponding dilepton -spectra are found to
be very similar, the inclusive dilepton yield in the invariant mass range GeV should allow to disentangle the two scenarios
experimentally.Comment: 13 pages RevTeX slightly revised, 6 eps-figure
Isospin Multiplet Structure in Ultra--Heavy Fermion Bound States
The coupled Bethe--Salpeter bound state equations for a system,
where is a degenerate, fourth generation, super--heavy quark doublet,
are solved in several ladder approximation models. The exchanges of gluon,
Higgs and Goldstone modes in the standard model are calculated in the
ultra--heavy quark limit where weak and contributions are
negligible. A natural and multiplet pattern is found, with large
splittings occuring between the different weak iso--spin states when , the
quark masses, are larger than values in the range ,
depending on which model is used. Consideration of ultra--heavy quark lifetime
constraints and mass splitting constraints are reviewed to establish the
plausibility of lifetime and mass degeneracy requirements assumed for this
paper.Comment: 20 pages, 7 figures (hard copy available upon request), report#
KU-HEP-93-2
Thermometry with spin-dependent lattices
We propose a method for measuring the temperature of strongly correlated
phases of ultracold atom gases confined in spin-dependent optical lattices. In
this technique, a small number of "impurity" atoms--trapped in a state that
does not experience the lattice potential--are in thermal contact with atoms
bound to the lattice. The impurity serves as a thermometer for the system
because its temperature can be straightforwardly measured using time-of-flight
expansion velocity. This technique may be useful for resolving many open
questions regarding thermalization in these isolated systems. We discuss the
theory behind this method and demonstrate proof-of-principle experiments,
including the first realization of a 3D spin-dependent lattice in the strongly
correlated regime.Comment: 22 pages, 8 figures v2: Several references added; Section on heating
rates updated to include dipole fluctuation terms; Section added on the
limitations of the proposed method. To appear in New Journal of Physic
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