2,113 research outputs found
Clustering Assisted Fundamental Matrix Estimation
In computer vision, the estimation of the fundamental matrix is a basic
problem that has been extensively studied. The accuracy of the estimation
imposes a significant influence on subsequent tasks such as the camera
trajectory determination and 3D reconstruction. In this paper we propose a new
method for fundamental matrix estimation that makes use of clustering a group
of 4D vectors. The key insight is the observation that among the 4D vectors
constructed from matching pairs of points obtained from the SIFT algorithm,
well-defined cluster points tend to be reliable inliers suitable for
fundamental matrix estimation. Based on this, we utilizes a recently proposed
efficient clustering method through density peaks seeking and propose a new
clustering assisted method. Experimental results show that the proposed
algorithm is faster and more accurate than currently commonly used methods.Comment: 12 pages, 8 figures, 3 tables, Second International Conference on
Computer Science and Information Technology (COSIT 2015) March 21~22, 2015,
Geneva, Switzerlan
Cosmological constraints from Radial Baryon Acoustic Oscillation measurements and Observational Hubble data
We use the Radial Baryon Acoustic Oscillation (RBAO) measurements, distant
type Ia supernovae (SNe Ia), the observational data (OHD) and the Cosmic
Microwave Background (CMB) shift parameter data to constrain cosmological
parameters of CDM and XCDM cosmologies and further examine the role of
OHD and SNe Ia data in cosmological constraints. We marginalize the likelihood
function over by integrating the probability density to obtain the best fitting results and the confidence regions
in the plane.With the combination analysis for
both of the {\rm }CDM and XCDM models, we find that the confidence
regions of 68.3%, 95.4% and 99.7% levels using OHD+RBAO+CMB data are in good
agreement with that of SNe Ia+RBAO+CMB data which is consistent with the result
of Lin et al's work. With more data of OHD, we can probably constrain the
cosmological parameters using OHD data instead of SNe Ia data in the future.Comment: 8 pages, 6 figures, 2 tables, accepted for publication in Physics
Letters
Constraints on the DGP Universe using observational Hubble parameter
AbstractIn this work, we use observations of the Hubble parameter from the differential ages of passively evolving galaxies and the recent detection of the Baryon Acoustic Oscillations (BAO) at z1=0.35 to constrain the DvaliāGabadadzeāPorrati (DGP) Universe. For the case with a curvature term, we set a prior h=0.73Ā±0.03 and the best-fit values suggest a spatially closed Universe. For a flat Universe, we set h free and we get consistent results with other recent analyses
STI571 reduces TRAIL-induced apoptosis in colon cancer cells: c-Abl activation by the death receptor leads to stress kinase-dependent cell death
<p>Abstract</p> <p>Background</p> <p>In an effort to achieve better cancer therapies, we elucidated the combination cancer therapy of STI571 (an inhibitor of Bcr-Abl and clinically used for chronic myelogenous leukemia) and TNF-related apoptosis-inducing ligand (TRAIL, a developing antitumor agent) in leukemia, colon, and prostate cancer cells.</p> <p>Methods</p> <p>Colon cancer (HCT116, SW480), prostate cancer (PC3, LNCaP) and leukemia (K562) cells were treated with STI571 and TRAIL. Cell viability was determined by MTT assay and sub-G1 appearance. Protein expression and kinase phosphorylation were determined by Western blotting. c-Abl and p73 activities were inhibited by target-specific small interfering (si)RNA. In vitro kinase assay of c-Abl was conducted using CRK as a substrate.</p> <p>Results</p> <p>We found that STI571 exerts opposite effects on the antitumor activity of TRAIL. It enhanced cytotoxicity in TRAIL-treated K562 leukemia cells and reduced TRAIL-induced apoptosis in HCT116 and SW480 colon cancer cells, while having no effect on PC3 and LNCaP cells. In colon and prostate cancer cells, TRAIL caused c-Abl cleavage to the active form via a caspase pathway. Interestingly, JNK and p38 MAPK inhibitors effectively blocked TRAIL-induced toxicity in the colon, but not in prostate cancer cells. Next, we found that STI571 could attenuate TRAIL-induced c-Abl, JNK and p38 activation in HCT116 cells. In addition, siRNA targeting knockdown of c-Abl and p73 also reduced TRAIL-induced cytotoxicity, rendering HCT116 cells less responsive to stress kinase activation, and masking the cytoprotective effect of STI571.</p> <p>Conclusions</p> <p>All together we demonstrate a novel mediator role of p73 in activating the stress kinases p38 and JNK in the classical apoptotic pathway of TRAIL. TRAIL via caspase-dependent action can sequentially activate c-Abl, p73, and stress kinases, which contribute to apoptosis in colon cancer cells. Through the inhibition of c-Abl-mediated apoptotic p73 signaling, STI571 reduces the antitumor activity of TRAIL in colon cancer cells. Our results raise additional concerns when developing combination cancer therapy with TRAIL and STI571 in the future.</p
Constraints on smoothness parameter and dark energy using observational data
The universe, with large-scale homogeneity, is locally inhomogeneous,
clustering into stars, galaxies and larger structures. Such property is
described by the smoothness parameter which is defined as the
proportion of matter in the form of intergalactic medium. If we take
consideration of the inhomogeneities in small scale, there should be
modifications of the cosmological distances compared to a homogenous model.
Dyer and Roeder developed a second-order ordinary differential equation (D-R
equation) that describes the angular diameter distance-redshift relation for
inhomogeneous cosmological models. Furthermore, we may obtain the D-R equation
for observational data (OHD). The density-parameter ,
the state of dark energy , and the smoothness-parameter are
constrained by a set of OHD in a spatially flat CDM universe as well
as a spatially flat XCDM universe. By using of minimization method we
get and at
confidence level. If we assume a Gaussian prior of , we get and . For XCDM model, is constrained to
but is weakly constrained around -1, where
describes the equation of the state of the dark energy (). We conclude that OHD constrains the smoothness
parameter more effectively than the data of SNe Ia and compact radio sources.Comment: 11 pages, 12 figures, accepted for publication in Research in
Astronomy and Astrophysic
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