4,464 research outputs found
Fast Graph-Based Object Segmentation for RGB-D Images
Object segmentation is an important capability for robotic systems, in
particular for grasping. We present a graph- based approach for the
segmentation of simple objects from RGB-D images. We are interested in
segmenting objects with large variety in appearance, from lack of texture to
strong textures, for the task of robotic grasping. The algorithm does not rely
on image features or machine learning. We propose a modified Canny edge
detector for extracting robust edges by using depth information and two simple
cost functions for combining color and depth cues. The cost functions are used
to build an undirected graph, which is partitioned using the concept of
internal and external differences between graph regions. The partitioning is
fast with O(NlogN) complexity. We also discuss ways to deal with missing depth
information. We test the approach on different publicly available RGB-D object
datasets, such as the Rutgers APC RGB-D dataset and the RGB-D Object Dataset,
and compare the results with other existing methods
A classical picture of subnanometer junctions: an atomistic Drude approach to nanoplasmonics
The description of optical properties of subnanometer junctions is
particularly challenging. Purely classical approaches fail, because the quantum
nature of electrons needs to be considered. Here we report on a novel classical
fully atomistic approach, {\omega}FQ, based on the Drude model for conduction
in metals, classical electrostatics and quantum tunneling. We show that
{\omega}FQ is able to reproduce the plasmonic behavior of complex metal
subnanometer junctions with quantitative fidelity to full ab initio
calculations. Besides the practical potentialities of our approach for large
scale nanoplasmonic simulations, we show that a classical approach, in which
the atomistic discretization of matter is properly accounted for, can
accurately describe the nanoplasmonics phenomena dominated by quantum effects.Comment: This article is licensed under a Creative Commons Attribution 3.0
Unported Licenc
Use of ANTARES and IceCube data to constrain a single power-law neutrino flux
We perform the first statistical combined analysis of the diffuse neutrino
flux observed by ANTARES (nine-year) and IceCube (six-year) by assuming a
single astrophysical power-law flux. The combined analysis reduces by a few
percent the best-fit values for the flux normalization and the spectral index.
Both data samples show an excess in the same energy range (40--200 TeV),
suggesting the presence of a second component. We perform a goodness-of-fit
test to scrutinize the null assumption of a single power-law, scanning
different values for the spectral index. The addition of the ANTARES data
reduces the -value by a factor 23. In particular, a single power-law
component in the neutrino flux with the spectral index deduced by the six-year
up-going muon neutrinos of IceCube is disfavored with a -value smaller than
.Comment: 6 pages, 4 figures. Version published in AP
Dense 3D Object Reconstruction from a Single Depth View
In this paper, we propose a novel approach, 3D-RecGAN++, which reconstructs
the complete 3D structure of a given object from a single arbitrary depth view
using generative adversarial networks. Unlike existing work which typically
requires multiple views of the same object or class labels to recover the full
3D geometry, the proposed 3D-RecGAN++ only takes the voxel grid representation
of a depth view of the object as input, and is able to generate the complete 3D
occupancy grid with a high resolution of 256^3 by recovering the
occluded/missing regions. The key idea is to combine the generative
capabilities of autoencoders and the conditional Generative Adversarial
Networks (GAN) framework, to infer accurate and fine-grained 3D structures of
objects in high-dimensional voxel space. Extensive experiments on large
synthetic datasets and real-world Kinect datasets show that the proposed
3D-RecGAN++ significantly outperforms the state of the art in single view 3D
object reconstruction, and is able to reconstruct unseen types of objects.Comment: TPAMI 2018. Code and data are available at:
https://github.com/Yang7879/3D-RecGAN-extended. This article extends from
arXiv:1708.0796
Learning with Training Wheels: Speeding up Training with a Simple Controller for Deep Reinforcement Learning
Deep Reinforcement Learning (DRL) has been applied successfully to many
robotic applications. However, the large number of trials needed for training
is a key issue. Most of existing techniques developed to improve training
efficiency (e.g. imitation) target on general tasks rather than being tailored
for robot applications, which have their specific context to benefit from. We
propose a novel framework, Assisted Reinforcement Learning, where a classical
controller (e.g. a PID controller) is used as an alternative, switchable policy
to speed up training of DRL for local planning and navigation problems. The
core idea is that the simple control law allows the robot to rapidly learn
sensible primitives, like driving in a straight line, instead of random
exploration. As the actor network becomes more advanced, it can then take over
to perform more complex actions, like obstacle avoidance. Eventually, the
simple controller can be discarded entirely. We show that not only does this
technique train faster, it also is less sensitive to the structure of the DRL
network and consistently outperforms a standard Deep Deterministic Policy
Gradient network. We demonstrate the results in both simulation and real-world
experiments.Comment: Published in ICRA2018. The code is now available at
https://github.com/xie9187/AsDDP
The role of microRNAs in thyroid carcinomas
Thyroid cancers (TCs) are the most common malignancies of endocrine organs. They originate from cells of different origin within the thyroid gland, which is located at the base of the neck. Several forms of TCs have been classified and great variability is observed in molecular, cellular and clinical features. The most common forms have favorable prognosis but a number of very aggressive TCs, which are characterized by a less differentiated cellular phenotype, have no effective treatment at the moment. While TC causes are not completely understood, many genetic factors involved in their onset have been discovered. In particular, activating mutations of BRAF, RET or RAS genes are known to be specifically associated with TC initiation, progression and outcome. The involvement of microRNAs in thyroid neoplasms has recently changed the paradigm for biomarker discovery in TC, suggesting that these small non-coding RNAs could be used to develop, refine or strengthen strategies for diagnosis and management of TCs. In this review, the importance of microRNA profiling in TC is explored suggesting that these molecules can be included in procedures that can perform better than any known clinical index in the identification of adverse outcomes
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