14,620 research outputs found
Energy Spectrum Extraction and Optimal Imaging via Dual-Energy Material Decomposition
Inferior soft-tissue contrast resolution is a major limitation of current CT
scanners. The aim of the study is to improve the contrast resolution of CT
scanners using dual-energy acquisition. Based on dual-energy material
decomposition, the proposed method starts with extracting the outgoing energy
spectrum by polychromatic forward projecting the material-selective images. The
extracted spectrum is then reweighted to boost the soft-tissue contrast. A
simulated water cylinder phantom with inserts that contain a series of six
solutions of varying iodine concentration (range, 0-20 mg/mL) is used to
evaluate the proposed method. Results show the root mean square error (RMSE)
and mean energy difference between the extracted energy spectrum and the
spectrum acquired using an energy-resolved photon counting detector(PCD), are
0.044 and 0.01 keV, respectively. Compared to the method using the standard
energy-integrating detectors, dose normalized contrast-to-noise ratio (CNRD)
for the proposed method are improved from 1 to 2.15 and from 1 to 1.88 for the
8 mg/mL and 16 mg/mL iodine concentration inserts, respectively. The results
show CT image reconstructed using the proposed method is superior to the image
reconstructed using the standard method that using an energy-integrating
detector.Comment: 4 pages, 4 figures in The 2015 IEEE Nuclear Science Symposium and
Medical Imaging Conference Recor
Algebraic Cayley Graphs over Finite Fields
A new algebraic Cayley graph is constructed using finite fields. Its
connectedness and diameter bound are studied via Weil's estimate for character
sums. These graphs provide a new source of expander graphs, extending classical
results of Chung
Tac2Structure: Object Surface Reconstruction Only through Multi Times Touch
Inspired by humans' ability to perceive the surface texture of unfamiliar
objects without relying on vision, the sense of touch can play a crucial role
in robots exploring the environment, particularly in scenes where vision is
difficult to apply, or occlusion is inevitable. Existing tactile surface
reconstruction methods rely on external sensors or have strong prior
assumptions, making the operation complex and limiting their application
scenarios. This paper presents a framework for low-drift surface reconstruction
through multiple tactile measurements, Tac2Structure. Compared with existing
algorithms, the proposed method uses only a new vision-based tactile sensor
without relying on external devices. Aiming at the difficulty that
reconstruction accuracy is easily affected by the pressure at contact, we
propose a correction algorithm to adapt it. The proposed method also reduces
the accumulative errors that occur easily during global object surface
reconstruction. Multi-frame tactile measurements can accurately reconstruct
object surfaces by jointly using the point cloud registration algorithm,
loop-closure detection algorithm based on deep learning, and pose graph
optimization algorithm. Experiments verify that Tac2Structure can achieve
millimeter-level accuracy in reconstructing the surface of objects, providing
accurate tactile information for the robot to perceive the surrounding
environment.Comment: Accepted for publication in IEEE Robotics And Automation Letter
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A supramolecular radical cation: folding-enhanced electrostatic effect for promoting radical-mediated oxidation.
We report a supramolecular strategy to promote radical-mediated Fenton oxidation by the rational design of a folded host-guest complex based on cucurbit[8]uril (CB[8]). In the supramolecular complex between CB[8] and a derivative of 1,4-diketopyrrolo[3,4-c]pyrrole (DPP), the carbonyl groups of CB[8] and the DPP moiety are brought together through the formation of a folded conformation. In this way, the electrostatic effect of the carbonyl groups of CB[8] is fully applied to highly improve the reactivity of the DPP radical cation, which is the key intermediate of Fenton oxidation. As a result, the Fenton oxidation is extraordinarily accelerated by over 100 times. It is anticipated that this strategy could be applied to other radical reactions and enrich the field of supramolecular radical chemistry in radical polymerization, photocatalysis, and organic radical battery and holds potential in supramolecular catalysis and biocatalysis
Descriptions of five new species of Helina Robineau-Desvoidy (Diptera: Muscidae) from China
In this paper, five new species belonging to the genus Helina Robineau-Desvoidy are described and illustrated, viz H. combinisetata sp. n., H. discombinisetata sp. n., H. flavipulchella sp. n., H. subsetiventris sp. n., H. xingkaiensis sp. n. Revised couplets for the key to known Chinese species are given
BH3 mimetic ABT-737 sensitizes colorectal cancer cells to ixazomib through MCL-1 downregulation and autophagy inhibition.
The proteasome inhibitor MLN9708 is an orally administered drug that is hydrolyzed into its active form, MLN2238 (ixazomib). Compared with Bortezomib, MLN2238 has a shorter proteasome dissociation half-life and a lower incidence and severity of peripheral neuropathy, which makes it an attractive candidate for colorectal cancer treatment. In the present study, we observed that MLN2238 induced autophagy, as evidenced by conversion of the autophagosomal marker LC3 from LC3I to LC3II, in colorectal cancer cell lines. Mcl-1, an anti-apoptotic Bcl-2 family protein, was markedly elevated after treating a colorectal cancer cell line with MLN2238. We proved that inhibiting Mcl-1 expression enhances MLN2238 induced apoptosis and negatively regulates autophagy. Co-administration of BH3 mimetic ABT-737 with MLN2238 synergistically kills colorectal cancer cells through MCL-1 neutralization and autophagy inhibition. Furthermore, the synergistic killing effect of the combination therapy is correlated with P53 status in colorectal cancer. These data highlight that the combination of ABT-737 with MLN9708 is a promising therapeutic strategy for human colorectal cancer
Numerical Simulation of Fragment Separation during Rock Cutting Using a 3D Dynamic Finite Element Analysis Code
To predict fragment separation during rock cutting, previous studies on rock cutting interactions using simulation approaches, experimental tests, and theoretical methods were considered in detail. This study used the numerical code LS-DYNA (3D) to numerically simulate fragment separation. In the simulations, a damage material model and erosion criteria were used for the base rock, and the conical pick was designated a rigid material. The conical pick moved at varying linear speeds to cut the fixed base rock. For a given linear speed of the conical pick, numerical studies were performed for various cutting depths and mechanical properties of rock. The numerical simulation results demonstrated that the cutting forces and sizes of the separated fragments increased significantly with increasing cutting depth, compressive strength, and elastic modulus of the base rock. A strong linear relationship was observed between the mean peak cutting forces obtained from the numerical, theoretical, and experimental studies with correlation coefficients of 0.698, 0.8111, 0.868, and 0.768. The simulation results also showed an exponential relationship between the specific energy and cutting depth and a linear relationship between the specific energy and compressive strength. Overall, LS-DYNA (3D) is effective and reliable for predicting the cutting performance of a conical pick
TransY-Net:Learning Fully Transformer Networks for Change Detection of Remote Sensing Images
In the remote sensing field, Change Detection (CD) aims to identify and
localize the changed regions from dual-phase images over the same places.
Recently, it has achieved great progress with the advances of deep learning.
However, current methods generally deliver incomplete CD regions and irregular
CD boundaries due to the limited representation ability of the extracted visual
features. To relieve these issues, in this work we propose a novel
Transformer-based learning framework named TransY-Net for remote sensing image
CD, which improves the feature extraction from a global view and combines
multi-level visual features in a pyramid manner. More specifically, the
proposed framework first utilizes the advantages of Transformers in long-range
dependency modeling. It can help to learn more discriminative global-level
features and obtain complete CD regions. Then, we introduce a novel pyramid
structure to aggregate multi-level visual features from Transformers for
feature enhancement. The pyramid structure grafted with a Progressive Attention
Module (PAM) can improve the feature representation ability with additional
inter-dependencies through spatial and channel attentions. Finally, to better
train the whole framework, we utilize the deeply-supervised learning with
multiple boundary-aware loss functions. Extensive experiments demonstrate that
our proposed method achieves a new state-of-the-art performance on four optical
and two SAR image CD benchmarks. The source code is released at
https://github.com/Drchip61/TransYNet.Comment: This work is accepted by TGRS2023. It is an extension of our ACCV2022
paper and arXiv:2210.0075
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