13,612 research outputs found
A novel cryptosystem based on iris key generation
Author name used in this publication: David ZhangBiometrics Research Centre, Department of ComputingVersion of RecordPublishe
An iris cryptosystem for information security
Author name used in this publication: David ZhangBiometrics Research Centre, Department of ComputingVersion of RecordPublishe
Alternate proof of the Rowe-Rosensteel proposition and seniority conservation
For a system with three identical nucleons in a single- shell, the states
can be written as the angular momentum coupling of a nucleon pair and the odd
nucleon. The overlaps between these non-orthonormal states form a matrix which
coincides with the one derived by Rowe and Rosensteel [Phys. Rev. Lett. {\bf
87}, 172501 (2001)]. The propositions they state are related to the eigenvalue
problems of the matrix and dimensions of the associated subspaces. In this
work, the propositions will be proven from the symmetric properties of the
symbols. Algebraic expressions for the dimension of the states, eigenenergies
as well as conditions for conservation of seniority can be derived from the
matrix.Comment: 9 pages, no figur
Monotonicity and logarithmic convexity relating to the volume of the unit ball
Let stand for the volume of the unit ball in for
. In the present paper, we prove that the sequence
is logarithmically convex and that the sequence
is strictly
decreasing for . In addition, some monotonic and concave properties of
several functions relating to are extended and generalized.Comment: 12 page
From Fractional Chern Insulators to a Fractional Quantum Spin Hall Effect
We investigate the algebraic structure of flat energy bands a partial filling
of which may give rise to a fractional quantum anomalous Hall effect (or a
fractional Chern insulator) and a fractional quantum spin Hall effect. Both
effects arise in the case of a sufficiently flat energy band as well as a
roughly flat and homogeneous Berry curvature, such that the global Chern
number, which is a topological invariant, may be associated with a local
non-commutative geometry. This geometry is similar to the more familiar
situation of the fractional quantum Hall effect in two-dimensional electron
systems in a strong magnetic field.Comment: 8 pages, 3 figure; published version with labels in Figs. 2 and 3
correcte
The Characteristics of Vascular Growth in VX2 Tumor Measured by MRI and Micro-CT
Blood supply is crucial for rapid growth of a malignant tumor; medical imaging can play an important role in evaluating the vascular characterstics of tumors. Magnetic resonance imaging (MRI) and micro-computed tomography (CT) are able to detect tumors and measure blood volumes of microcirculation in tissue. In this study, we used MR imaging and micro-CT to assess the microcirculation in a VX2 tumor model in rabbits. MRI characterization was performed using the intravascular contrast agent Clariscan (NC100150-Injection); micro-CT with Microfil was used to directly depict blood vessels with diameters as low as 17 um in tissue. Relative blood volume fraction (rBVF) in the tumor rim and blood vessel density (rBVD) over the whole tumor was calculated using the two imaging methods. Our study indicates that rBVF is negatively related to the volume of the tumor measured by ultrasound (R = 0.90). rBVF in the tissue of a VX2 tumor measured by MRI in vivo was qualitatively consistent with the rBVD demonstrated by micro-CT in vitro (R = 0.97). The good correlation between the two methods indicates that MRI studies are potentially valuable for assessing characteristics or tumor vascularity and for assessing response to therapy noninvasively
Theory of Andreev reflection in a two-orbital model of iron-pnictide superconductors
A recently developed theory for the problem of Andreev reflection between a
normal metal (N) and a multiband superconductor (MBS) assumes that the incident
wave from the normal metal is coherently transmitted through several bands
inside the superconductor. Such splitting of the probability amplitude into
several channels is the analogue of a quantum waveguide. Thus, the appropriate
matching conditions for the wave function at the N/MBS interface are derived
from an extension of quantum waveguide theory. Interference effects between the
transmitted waves inside the superconductor manifest themselves in the
conductance. We provide results for a FeAs superconductor, in the framework of
a recently proposed effective two-band model and two recently proposed gap
symmetries: in the sign-reversed s-wave () scenario
resonant transmission through surface Andreev bound states (ABS) at nonzero
energy is found as well as destructive interference effects that produce zeros
in the conductance; in the extended s-wave ()
scenario no ABS at finite energy are found.Comment: 4 pages, 5 figure
Near-bandgap wavelength-dependent studies of long-lived traveling coherent longitudinal acoustic phonon oscillations in GaSb/GaAs systems
We report first studies of long-lived oscillations in optical pump-probe
measurements on GaSb-GaAs heterostructures. The oscillations arise from a
photogenerated coherent longitudinal acoustic phonon wave, which travels from
the top surface of GaSb across the interface into the GaAs substrate, providing
information on the optical properties of the material as a function of
time/depth. Wavelength-dependent studies of the oscillations near the bandgap
of GaAs indicate strong correlations to the optical properties of GaAs.Comment: 11 pages, 4 figure
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