133 research outputs found
3D Neighborhood Convolution: Learning Depth-Aware Features for RGB-D and RGB Semantic Segmentation
A key challenge for RGB-D segmentation is how to effectively incorporate 3D
geometric information from the depth channel into 2D appearance features. We
propose to model the effective receptive field of 2D convolution based on the
scale and locality from the 3D neighborhood. Standard convolutions are local in
the image space (), often with a fixed receptive field of 3x3 pixels. We
propose to define convolutions local with respect to the corresponding point in
the 3D real-world space (), where the depth channel is used to adapt
the receptive field of the convolution, which yields the resulting filters
invariant to scale and focusing on the certain range of depth. We introduce 3D
Neighborhood Convolution (3DN-Conv), a convolutional operator around 3D
neighborhoods. Further, we can use estimated depth to use our RGB-D based
semantic segmentation model from RGB input. Experimental results validate that
our proposed 3DN-Conv operator improves semantic segmentation, using either
ground-truth depth (RGB-D) or estimated depth (RGB)
Kernel Learning in Ridge Regression "Automatically" Yields Exact Low Rank Solution
We consider kernels of the form
parametrized by . For such kernels, we study a variant of the kernel
ridge regression problem which simultaneously optimizes the prediction function
and the parameter of the reproducing kernel Hilbert space. The
eigenspace of the learned from this kernel ridge regression problem
can inform us which directions in covariate space are important for prediction.
Assuming that the covariates have nonzero explanatory power for the response
only through a low dimensional subspace (central mean subspace), we find that
the global minimizer of the finite sample kernel learning objective is also low
rank with high probability. More precisely, the rank of the minimizing
is with high probability bounded by the dimension of the central mean subspace.
This phenomenon is interesting because the low rankness property is achieved
without using any explicit regularization of , e.g., nuclear norm
penalization.
Our theory makes correspondence between the observed phenomenon and the
notion of low rank set identifiability from the optimization literature. The
low rankness property of the finite sample solutions exists because the
population kernel learning objective grows "sharply" when moving away from its
minimizers in any direction perpendicular to the central mean subspace.Comment: Add code links and correct a figur
Experimental investigation of dielectric barrier impact on breakdown voltage enhancement of copper wire-plane electrode systems
Non-pressurized air is extensively used as basic insulation media in medium / high voltage equipments. An inherent property of air-insulated designs is that the systems tend to become physically large. Application of Dielectric barrier can increase the breakdown voltage and therefore decrease the size of the equipments.
In this paper, the impact of dielectric barrier on breakdown voltage enhancement of a copper wire-plane system is investigated. For this purpose, the copper wire is covered with different dielectric materials. Depending on the air gap and dielectric strength of the barrier the breakdown can be initiated in the solid or gas dielectric. Theoretically, free charges are affected by the electric field between the electrodes and accumulated at the dielectric surface, this leads to the reduction of electric field in air gap and enhancement of the ifield in the dielectric layer. Therefore, with appropriate selection of the barrier thickness and material, it is possible to increase the breakdown voltage of the insulation system. The influence of different parameters like inter-electrode spacing, and dielectric material on the break-down voltage is investigated for applied 50 Hz AC and DC voltages. The results indicate that up to 240% increase of the breakdown voltage can be achieved
Neural Feature Matching in Implicit 3D Representations
Recently, neural implicit functions have achieved impressive results for encoding 3D shapes. Conditioning on low-dimensional latent codes generalises a single implicit function to learn shared representation space for a variety of shapes, with the advantage of smooth interpolation. While the benefits from the global latent space do not correspond to explicit points at local level, we propose to track the continuous point trajectory by matching implicit features with the latent code interpolating between shapes, from which we corroborate the hierarchical functionality of the deep implicit functions, where early layers map the latent code to fitting the coarse shape structure, and deeper layers further refine the shape details. Furthermore, the structured representation space of implicit functions enables to apply feature matching for shape deformation, with the benefits to handle topology and semantics inconsistency, such as from an armchair to a chair with no arms, without explicit flow functions or manual annotations
Dual-agonist occupancy of orexin receptor 1 and cholecystokinin A receptor heterodimers decreases G-protein-dependent signaling and migration in the human colon cancer cell line HT-29
The orexin (OX1R) and cholecystokinin A (CCK1R) receptors play opposing roles in the migration of the human colon cancer cell line HT-29, and may be involved in the pathogenesis and pathophysiology of cancer cell invasion and metastasis. OX1R and CCK1R belong to family A of the G-protein-coupled receptors (GPCRs), but the detailed mechanisms underlying their functions in solid tumor development remain unclear. In this study, we investigated whether these two receptors heterodimerize, and the results revealed novel signal transduction mechanisms. Bioluminescence and Förster resonance energy transfer, as well as proximity ligation assays, demonstrated that OX1R and CCK1R heterodimerize in HEK293 and HT-29 cells, and that peptides corresponding to transmembrane domain 5 of OX1R impaired heterodimer formation. Stimulation of OX1R and CCK1R heterodimers with both orexin-A and CCK decreased the activation of Gαq, Gαi2, Gα12, and Gα13 and the migration of HT-29 cells in comparison with stimulation with orexin-A or CCK alone, but did not alter GPCR interactions with β-arrestins. These results suggest that OX1R and CCK1R heterodimerization plays an anti-migratory role in human colon cancer cells. [Abstract copyright: Copyright © 2017. Published by Elsevier B.V.
MANGO: A Mask Attention Guided One-Stage Scene Text Spotter
Recently end-to-end scene text spotting has become a popular research topic
due to its advantages of global optimization and high maintainability in real
applications. Most methods attempt to develop various region of interest (RoI)
operations to concatenate the detection part and the sequence recognition part
into a two-stage text spotting framework. However, in such framework, the
recognition part is highly sensitive to the detected results (e.g.), the
compactness of text contours). To address this problem, in this paper, we
propose a novel Mask AttentioN Guided One-stage text spotting framework named
MANGO, in which character sequences can be directly recognized without RoI
operation. Concretely, a position-aware mask attention module is developed to
generate attention weights on each text instance and its characters. It allows
different text instances in an image to be allocated on different feature map
channels which are further grouped as a batch of instance features. Finally, a
lightweight sequence decoder is applied to generate the character sequences. It
is worth noting that MANGO inherently adapts to arbitrary-shaped text spotting
and can be trained end-to-end with only coarse position information (e.g.),
rectangular bounding box) and text annotations. Experimental results show that
the proposed method achieves competitive and even new state-of-the-art
performance on both regular and irregular text spotting benchmarks, i.e., ICDAR
2013, ICDAR 2015, Total-Text, and SCUT-CTW1500.Comment: Accepted to AAAI2021. Code is available at
https://davar-lab.github.io/publication.html or
https://github.com/hikopensource/DAVAR-Lab-OC
Individual phosphorylation sites at the C-terminus of the apelin receptor play different roles in signal transduction
The apelin and Elabela proteins constitute a spatiotemporal double-ligand system that controls apelin receptor (APJ) signal transduction. Phosphorylation of multiple sites within the C-terminus of APJ is essential for the recruitment of β-arrestins. We sought to determine the precise mechanisms by which apelin and Elabela promote APJ phosphorylation, and to elucidate the influence of β-arrestin phosphorylation on G-protein-coupled receptor (GPCR)/β-arrestin-dependent signaling. We used techniques including mass spectrometry (MS), mutation analysis, and bioluminescence resonance energy transfer (BRET) to evaluate the role of phosphorylation sites in APJ-mediated G-protein-dependent and β-dependent signaling. Phosphorylation of APJ occurred at five serine residues in the C-terminal region (Ser335, Ser339, Ser345, Ser348 and Ser369). We also identified two phosphorylation sites in β-arrestin1 and three in β-arrestin2, including three previously identified residues (Ser412, Ser361, and Thr383) and two new sites, Tyr47 in β-arrestin1 and Tyr48 in β-arrestin2. APJ mutations did not affect the phosphorylation of β-arrestins, but it affects the β-arrestin signaling pathway, specifically Ser335 and Ser339. Mutation of Ser335 decreased the ability of the receptor to interact with β-arrestin1/2 and AP2, indicating that APJ affects the β-arrestin signaling pathway by stimulating Elabela. Mutation of Ser339 abolished the capability of the receptor to interact with GRK2 and β-arrestin1/2 upon stimulation with apelin-36, and disrupted receptor internalization and β-arrestin-dependent ERK1/2 activation. Five peptides act on distinct phosphorylation sites at the APJ C-terminus, differentially regulating APJ signal transduction and causing different biological effects. These findings may facilitate screening for drugs to treat cardiovascular and metabolic diseases
PointMixup: Augmentation for Point Clouds
This paper introduces data augmentation for point clouds by interpolation
between examples. Data augmentation by interpolation has shown to be a simple
and effective approach in the image domain. Such a mixup is however not
directly transferable to point clouds, as we do not have a one-to-one
correspondence between the points of two different objects. In this paper, we
define data augmentation between point clouds as a shortest path linear
interpolation. To that end, we introduce PointMixup, an interpolation method
that generates new examples through an optimal assignment of the path function
between two point clouds. We prove that our PointMixup finds the shortest path
between two point clouds and that the interpolation is assignment invariant and
linear. With the definition of interpolation, PointMixup allows to introduce
strong interpolation-based regularizers such as mixup and manifold mixup to the
point cloud domain. Experimentally, we show the potential of PointMixup for
point cloud classification, especially when examples are scarce, as well as
increased robustness to noise and geometric transformations to points. The code
for PointMixup and the experimental details are publicly available.Comment: Accepted as Spotlight presentation at European Conference on Computer
Vision (ECCV), 202
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