600,602 research outputs found
CAPTBHA: COMPLETELY AUTOMATED PROOF-OF-CONCEPT TEST TO TELL BOT AND HUMAN APART IMPLEMENTATION OF BOT DETECTION TECHNIQUE BASED ON WEB NAVIGATION BEHAVIOUR IN JACK-MAPS
CAPTBHA: COMPLETELY AUTOMATED PROOF-OF-CONCEPT TEST TO TELL BOT AND HUMAN APART IMPLEMENTATION OF BOT DETECTION TECHNIQUE BASED ON WEB NAVIGATION BEHAVIOUR IN JACK-MAPS
- Bot detection, web navigation behavior, link obfuscation, Support Vector Machine, KNearest
Neighbor, Naïve Bayes, Jack-Maps, Web 2.0, Spam 2.
Low-Temperature Spin Diffusion in a Spin-Polarized Fermi Gas
We present a finite temperature calculation of the transverse spin-diffusion
coefficient, , in a dilute degenerate Fermi gas in the presence of a
small external magnetic field, . While the longitudinal diffusion
coefficient displays the conventional low-temperature Fermi-liquid behavior,
, the corresponding results for show three
separate regimes: (a) for ; (b) , for and large spin-rotation
parameter , and (c) for and . Our results are qualitatively consistent with the available
experimental data in weakly spin-polarized and mixtures.Comment: 13 pages, REVTEX, 3 figures available upon request, RU-94-4
Reforming the BOT Law: A Call of the Times
Recent controversies about certain government infrastructure projects, especially those agreed upon under the framework of the build-operate-transfer (BOT) scheme, further raise the need to address various issues relating to both the legal and institutional aspects of the present BOT Law and its implementing rules and regulations. This Notes examines the matter more closely...BOT scheme, infrastructure development, BOT projects, BOT Law, public-private partnership (PPP), Investment Coordinating Committee (ICC)
T-Violation in Decay And Supersymmetry
Measurement of the transverse muon polarization in the decay will be attempted for the first time at the
ongoing KEK E246 experiment and also at a proposed BNL experiment. We provide a
general analysis of how is sensitive to the physical
-violating phases in new physics induced four-Fermi interactions, and then
we calculate the dominant contributions to from squark family
mixings in generic supersymmetric models. Estimates of the upper bounds on
are also given. It is found that a supersymmetry-induced
right-handed quark current from boson exchange gives an upper limit on
as large as a few per cent, whereas with
charged-Higgs-exchange induced pseudoscalar interaction, is no
larger than a few tenths of a per cent. Possible correlations between the muon
polarization measurements in and decays are discussed, and distinctive patterns of
this correlation from squark family-mixings and from the three-Higgs-doublet
model are noted.Comment: Revtex, 29 pages including 4 epsf figure
Fidelity susceptibility and general quench near an anisotropic quantum critical point
We study the scaling behavior of fidelity susceptibility density at or close to an anisotropic quantum critical point characterized by two
different correlation length exponents and along
parallel and perpendicular spatial directions, respectively. Our studies show
that the response of the system due to a small change in the Hamiltonian near
an anisotropic quantum critical point is different from that seen near an
isotropic quantum critical point. In particular, for a finite system with
linear dimension () in the parallel (perpendicular)
directions, the maximum value of is found to increases in a
power-law fashion with for small , with an exponent depending
on both and and eventually crosses over to a scaling
with for . We
also propose scaling relations of heat density and defect density generated
following a quench starting from an anisotropic quantum critical point and
connect them to a generalized fidelity susceptibility. These predictions are
verified exactly both analytically and numerically taking the example of a
Hamiltonian showing a semi-Dirac band-crossing point.Comment: 6 pages, 6 pigure
Radial evolution of the wave-vector anisotropy of solar wind turbulence between 0.3 and 1 AU
We present observations of the power spectral anisotropy in wave-vector space
of solar wind turbulence, and study how it evolves in interplanetary space with
increasing heliocentric distance. For this purpose we use magnetic field
measurements made by the Helios-2 spacecraft at three positions between 0.29
and 0.9 AU. To derive the power spectral density (PSD) in -space based on single-satellite measurements is a challenging task not
yet accomplished previously. Here we derive the spectrum
(, ) from the spatial
correlation function by a
transformation according to the projection-slice theorem. We find the so
constructed PSDs to be distributed in k-space mainly along a ridge that is more
inclined toward the than axis, a new result
which probably indicates preferential cascading of turbulent energy along the
direction. Furthermore, this ridge of the distribution is found
to gradually get closer to the axis, as the outer scale length of
the turbulence becomes larger while the solar wind flows further away from the
Sun. In the vicinity of the axis, there appears a minor
spectral component that probably corresponds to quasi-parallel Alfv\'enic
fluctuations. Their relative contribution to the total spectral density tends
to decrease with radial distance. These findings suggest that solar wind
turbulence undergoes an anisotropic cascade transporting most of its magnetic
energy towards larger , and that the anisotropy in the inertial
range is radially developing further at scales that are relatively far from the
ever increasing outer scale
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