2,887 research outputs found
Medical Image Segmentation Based on Multi-Modal Convolutional Neural Network: Study on Image Fusion Schemes
Image analysis using more than one modality (i.e. multi-modal) has been
increasingly applied in the field of biomedical imaging. One of the challenges
in performing the multimodal analysis is that there exist multiple schemes for
fusing the information from different modalities, where such schemes are
application-dependent and lack a unified framework to guide their designs. In
this work we firstly propose a conceptual architecture for the image fusion
schemes in supervised biomedical image analysis: fusing at the feature level,
fusing at the classifier level, and fusing at the decision-making level.
Further, motivated by the recent success in applying deep learning for natural
image analysis, we implement the three image fusion schemes above based on the
Convolutional Neural Network (CNN) with varied structures, and combined into a
single framework. The proposed image segmentation framework is capable of
analyzing the multi-modality images using different fusing schemes
simultaneously. The framework is applied to detect the presence of soft tissue
sarcoma from the combination of Magnetic Resonance Imaging (MRI), Computed
Tomography (CT) and Positron Emission Tomography (PET) images. It is found from
the results that while all the fusion schemes outperform the single-modality
schemes, fusing at the feature level can generally achieve the best performance
in terms of both accuracy and computational cost, but also suffers from the
decreased robustness in the presence of large errors in any image modalities.Comment: Zhe Guo and Xiang Li contribute equally to this wor
Confronting brane inflation with Planck and pre-Planck data
In this paper, we compare brane inflation models with the Planck data and the
pre-Planck data (which combines WMAP, ACT, SPT, BAO and H0 data). The Planck
data prefer a spectral index less than unity at more than 5\sigma confidence
level, and a running of the spectral index at around 2\sigma confidence level.
We find that the KKLMMT model can survive at the level of 2\sigma only if the
parameter (the conformal coupling between the Hubble parameter and the
inflaton) is less than , which indicates a certain level
of fine-tuning. The IR DBI model can provide a slightly larger negative running
of spectral index and red tilt, but in order to be consistent with the
non-Gaussianity constraints from Planck, its parameter also needs fine-tuning
at some level.Comment: 10 pages, 8 figure
Ising-like transitions in the O() loop model on the square lattice
We explore the phase diagram of the O() loop model on the square lattice
in the plane, where is the weight of a lattice edge covered by a
loop. These results are based on transfer-matrix calculations and finite-size
scaling. We express the correlation length associated with the staggered loop
density in the transfer-matrix eigenvalues. The finite-size data for this
correlation length, combined with the scaling formula, reveal the location of
critical lines in the diagram. For we find Ising-like phase transitions
associated with the onset of a checkerboard-like ordering of the elementary
loops, i.e., the smallest possible loops, with the size of an elementary face,
which cover precisely one half of the faces of the square lattice at the
maximum loop density. In this respect, the ordered state resembles that of the
hard-square lattice gas with nearest-neighbor exclusion, and the finiteness of
represents a softening of its particle-particle potentials. We also
determine critical points in the range . It is found that the
topology of the phase diagram depends on the set of allowed vertices of the
loop model. Depending on the choice of this set, the transition may
continue into the dense phase of the loop model, or continue as a
line of O() multicritical points
Special transitions in an O() loop model with an Ising-like constraint
We investigate the O() nonintersecting loop model on the square lattice
under the constraint that the loops consist of ninety-degree bends only. The
model is governed by the loop weight , a weight for each vertex of the
lattice visited once by a loop, and a weight for each vertex visited twice
by a loop. We explore the phase diagram for some values of . For
, the diagram has the same topology as the generic O() phase diagram
with , with a first-order line when starts to dominate, and an
O()-like transition when starts to dominate. Both lines meet in an
exactly solved higher critical point. For , the O()-like transition
line appears to be absent. Thus, for , the phase diagram displays
a line of phase transitions for . The line ends at in an
infinite-order transition. We determine the conformal anomaly and the critical
exponents along this line. These results agree accurately with a recent
proposal for the universal classification of this type of model, at least in
most of the range . We also determine the exponent describing
crossover to the generic O() universality class, by introducing topological
defects associated with the introduction of `straight' vertices violating the
ninety-degree-bend rule. These results are obtained by means of transfer-matrix
calculations and finite-size scaling.Comment: 19 pages, 11 figure
Magnetic Field Effect on Charmonium Production in High Energy Nuclear Collisions
It is important to understand the strong external magnetic field generated at
the very beginning of high energy nuclear collisions. We study the effect of
the magnetic field on the charmonium yield and anisotropic distribution in
Pb+Pb collisions at the LHC energy. The time dependent Schr\"odinger equation
is employed to describe the motion of pairs. We compare our model
prediction of non- collective anisotropic parameter of s with CMS
data at high transverse momentum. This is the first attempt to measure the
magnetic field in high energy nuclear collisions.Comment: 5 pages, 4 figure
Crossed Andreev effects in two-dimensional quantum Hall systems
We study the crossed Andreev effects in two-dimensional
conductor/superconductor hybrid systems under a perpendicular magnetic field.
Both a graphene/superconductor hybrid system and an electron gas/superconductor
one are considered. It is shown that an exclusive crossed Andreev reflection,
with other Andreev reflections being completely suppressed, is obtained in a
high magnetic field because of the chiral edge states in the quantum Hall
regime. Importantly, the exclusive crossed Andreev reflection not only holds
for a wide range of system parameters, e.g., the size of system, the width of
central superconductor, and the quality of coupling between the graphene and
the superconductor, but also is very robust against disorder. When the applied
bias is within the superconductor gap, a robust Cooper-pair splitting process
with high-efficiency can be realized in this system.Comment: 10 pages, 10 figure
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