1,059 research outputs found
The Research of Sequential Images: Rebuilding of Gray (Position) ~ Time Function on Direction Lines and Their Applications
Contrasted with other information carriers, such as speech and text, images contains larger amount of information, especially in sequential images, that is waiting to be exploited, in particular the dynamic information of correlation, difference, and temporal relationship between different frames. This dynamic information contributes a great deal in analysis of 4D images. This paper proposes a method for detecting dynamic information from sequential images, based on the rebuilding of their gray (position)~time function on direction lines, an approach that has been analyzed and studied extensively on the setting of various direction lines. This method is based on motion that is presented on sequential images. In particular, the method, Omni directional M-mode Echocardiography system, which we have studied extensively, will be described leading to a robust way of diagnosing heart diseases
Fabrication and Characterization of Fe-Doped In 2 O 3 Dilute Magnetic Semiconducting Nanowires
Sequence Specificity of BAL 31 Nuclease for ssDNA Revealed by Synthetic Oligomer Substrates Containing Homopolymeric Guanine Tracts
Background: The extracellular nuclease from Alteromonas espejiana, BAL 31 catalyzes the degradation of single-stranded and linear duplex DNA to 59-mononucleotides, cleaves negatively supercoiled DNA to the linear duplex form, and cleaves duplex DNA in response to the presence of apurinic sites. Principal Findings: In this work we demonstrate that BAL 31 activity is affected by the presence of guanine in singlestranded DNA oligomers. Specifically, nuclease activity is shown to be affected by guanine’s presence in minimal homopolymeric tracts in the middle of short oligomer substrates and also by its presence at the 39 end of ten and twenty base oligomers. GNC rich regions in dsDNA are known to cause a decrease in the enzyme’s nuclease activity which has been attributed to the increased thermal stability of these regions, thus making it more difficult to unwind the strands required for enzyme access. Our results indicate that an additional phenomenon could be wholly or partly responsible for the loss of activity in these GNC rich regions. Thus the presence of a guanine tract per se impairs the enzyme’s functionality, possibly due to the tract’s bulky nature and preventing efficient progression through the active site. Conclusions: This study has revealed that the general purpose BAL 31 nuclease commonly used in molecular genetics exhibits a hithertofore non-characterized degree of substrate specificity with respect to single-stranded DNA (ssDNA
Spawning rings of exceptional points out of Dirac cones
The Dirac cone underlies many unique electronic properties of graphene and
topological insulators, and its band structure--two conical bands touching at a
single point--has also been realized for photons in waveguide arrays, atoms in
optical lattices, and through accidental degeneracy. Deformations of the Dirac
cone often reveal intriguing properties; an example is the quantum Hall effect,
where a constant magnetic field breaks the Dirac cone into isolated Landau
levels. A seemingly unrelated phenomenon is the exceptional point, also known
as the parity-time symmetry breaking point, where two resonances coincide in
both their positions and widths. Exceptional points lead to counter-intuitive
phenomena such as loss-induced transparency, unidirectional transmission or
reflection, and lasers with reversed pump dependence or single-mode operation.
These two fields of research are in fact connected: here we discover the
ability of a Dirac cone to evolve into a ring of exceptional points, which we
call an "exceptional ring." We experimentally demonstrate this concept in a
photonic crystal slab. Angle-resolved reflection measurements of the photonic
crystal slab reveal that the peaks of reflectivity follow the conical band
structure of a Dirac cone from accidental degeneracy, whereas the complex
eigenvalues of the system are deformed into a two-dimensional flat band
enclosed by an exceptional ring. This deformation arises from the dissimilar
radiation rates of dipole and quadrupole resonances, which play a role
analogous to the loss and gain in parity-time symmetric systems. Our results
indicate that the radiation that exists in any open system can fundamentally
alter its physical properties in ways previously expected only in the presence
of material loss and gain
Clustering Property of Wolf-Rayet Galaxies in the SDSS
We have analysed, for the first time, the clustering properties of Wolf-Rayet
(W-R) galaxies, using a large sample of 846 W-R galaxies selected from the Data
Release 4 (DR4) of the SDSS. We compute the cross-correlation function between
W-R galaxies and a reference sample of galaxies drawn from the DR4. We compare
the function to the results for control samples of non-W-R star-forming
galaxies that are matched closely in redshift, luminosity, concentration,
4000-\AA break strength and specific star formation rate (SSFR). On scales
larger than a few Mpc, W-R galaxies have almost the same clustering amplitude
as the control samples, indicating that W-R galaxies and non-W-R control
galaxies populate dark matter haloes of similar masses. On scales between
0.1--1 Mpc, W-R galaxies are less clustered than the control samples,
and the size of the difference depends on the SSFR. Based on both observational
and theoretical considerations, we speculate that this negative bias can be
interpreted by W-R galaxies residing preferentially at the centers of their
dark matter haloes. We examine the distribution of W-R galaxies more closely
using the SDSS galaxy group catalogue of Yang et al., and find that 82%
of our W-R galaxies are the central galaxies of groups, compared to 74%
for the corresponding control galaxies. We find that W-R galaxies are hosted,
on average, by dark matter haloes of masses of, compared to
for centrally-located W-R galaxies and
for satellite ones. We would like to point out that this finding, which
provides a direct observational support to our conjecture, is really very crude
due to the small number of W-R galaxies and the incompleteness of the group
catalogue, and needs more work in future with larger samples.Comment: 8 pages, 5figure
Transition Form Factor up to within the Factorization Approach
In the paper, we apply the factorization approach to deal with the
transition form factor in the large recoil
regions. The B-meson wave functions and that include the
three-particle Fock states' contributions are adopted to give a consistent PQCD
analysis of the form factor up to . It has been found that
both the wave functions and can give sizable
contributions to the form factor and should be kept for a better understanding
of the meson decays. Then the contributions from different twist structures
of the kaon wavefunction are discussed, including the -breaking
effects. A sizable contribution from the twist-3 wave function is
found, whose model dependence is discussed by taking two group of parameters
that are determined by different distribution amplitude moments obtained in the
literature. It is also shown that and
, which are more
reasonable and consistent with the light-cone sum rule results in the large
recoil regions.Comment: 22 pages and 6 figure
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