138 research outputs found
Visual Map Construction Using RGB-D Sensors for Image-Based Localization in Indoor Environments
RGB-D sensors capture RGB images and depth images simultaneously, which makes it possible to acquire the depth information at pixel level. This paper focuses on the use of RGB-D sensors to construct a visual map which is an extended dense 3D map containing essential elements for image-based localization, such as poses of the database camera, visual features, and 3D structures of the building. Taking advantage of matched visual features and corresponding depth values, a novel local optimization algorithm is proposed to achieve point cloud registration and database camera pose estimation. Next, graph-based optimization is used to obtain the global consistency of the map. On the basis of the visual map, the image-based localization method is investigated, making use of the epipolar constraint. The performance of the visual map construction and the image-based localization are evaluated on typical indoor scenes. The simulation results show that the average position errors of the database camera and the query camera can be limited to within 0.2 meters and 0.9 meters, respectively
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The autophagic degradation of cytosolic pools of peroxisomal proteins by a new selective pathway.
Damaged or redundant peroxisomes and their luminal cargoes are removed by pexophagy, a selective autophagy pathway. In yeasts, pexophagy depends mostly on the pexophagy receptors, such as Atg30 for Pichia pastoris and Atg36 for Saccharomyces cerevisiae, the autophagy scaffold proteins, Atg11 and Atg17, and the core autophagy machinery. In P. pastoris, the receptors for peroxisomal matrix proteins containing peroxisomal targeting signals (PTSs) include the PTS1 receptor, Pex5, and the PTS2 receptor and co-receptor, Pex7 and Pex20, respectively. These shuttling receptors are predominantly cytosolic and only partially peroxisomal. It remains unresolved as to whether, when and how the cytosolic pools of peroxisomal receptors, as well as the peroxisomal matrix proteins, are degraded under pexophagy conditions. These cytosolic pools exist both in normal and mutant cells impaired in peroxisome biogenesis. We report here that Pex5 and Pex7, but not Pex20, are degraded by an Atg30-independent, selective autophagy pathway. To enter this selective autophagy pathway, Pex7 required its major PTS2 cargo, Pot1. Similarly, the degradation of Pex5 was inhibited in cells missing abundant PTS1 cargoes, such as alcohol oxidases and Fox2 (hydratase-dehydrogenase-epimerase). Furthermore, in cells deficient in PTS receptors, the cytosolic pools of peroxisomal matrix proteins, such as Pot1 and Fox2, were also removed by Atg30-independent, selective autophagy, under pexophagy conditions. In summary, the cytosolic pools of PTS receptors and their cargoes are degraded via a pexophagy-independent, selective autophagy pathway under pexophagy conditions. These autophagy pathways likely protect cells from futile enzymatic reactions that could potentially cause the accumulation of toxic cytosolic products.Abbreviations: ATG: autophagy related; Cvt: cytoplasm to vacuole targeting; Fox2: hydratase-dehydrogenase-epimerase; PAGE: polyacrylamide gel electrophoresis; Pot1: thiolase; PMP: peroxisomal membrane protein; Pgk1: 3-phosphoglycerate kinase; PTS: peroxisomal targeting signal; RADAR: receptor accumulation and degradation in the absence of recycling; RING: really interesting new gene; SDS: sodium dodecyl sulphate; TCA, trichloroacetic acid; Ub: ubiquitin; UPS: ubiquitin-proteasome system Vid: vacuole import and degradation
Optimal Design of a High Temperature Superconducting Homopolar Inductor Machine
A high temperature superconducting homopolar inductor machine (HTS-HIM) is optimally designed considering the effect of magnetic field on HTS coil in this paper. Firstly, the structure and operation principle of HTS-HIM are presented. The three-dimensional HTS-HIM finite element analysis model and two-dimensional axisymmetric direct coupling model of HTS-HIM based on T-A formulation are established. Secondly, the excitation window parameters, the excitation current and number of turns of HTS coil are optimized, taking into account the HTS-HIM performance and the safety of HTS coil. Thirdly, the magnetic field weakening capabilities of the U-shaped flux diverter and copper layer are analyzed and their parameters are optimized. Finally, the optimal design scheme and the critical current of HTS coil in HTS-HIM are obtained
A Wolf in Sheep's Clothing: Generalized Nested Jailbreak Prompts can Fool Large Language Models Easily
Large Language Models (LLMs), such as ChatGPT and GPT-4, are designed to
provide useful and safe responses. However, adversarial prompts known as
'jailbreaks' can circumvent safeguards, leading LLMs to generate harmful
content. Exploring jailbreak prompts can help to better reveal the weaknesses
of LLMs and further steer us to secure them. Unfortunately, existing jailbreak
methods either suffer from intricate manual design or require optimization on
another white-box model, compromising generalization or jailbreak efficiency.
In this paper, we generalize jailbreak prompt attacks into two aspects: (1)
Prompt Rewriting and (2) Scenario Nesting. Based on this, we propose ReNeLLM,
an automatic framework that leverages LLMs themselves to generate effective
jailbreak prompts. Extensive experiments demonstrate that ReNeLLM significantly
improves the attack success rate while greatly reducing the time cost compared
to existing baselines. Our study also reveals the inadequacy of current defense
methods in safeguarding LLMs. Finally, we offer detailed analysis and
discussion from the perspective of prompt execution priority on the failure of
LLMs' defense. We hope that our research can catalyze both the academic
community and LLMs vendors towards the provision of safer and more regulated
Large Language Models
Highly directional and coherent emission from dark excitons enabled by bound states in the continuum
A double-edged sword in two-dimensional material science and technology is an
optically forbidden dark exciton. On the one hand, it is fascinating for
condensed matter physics, quantum information processing, and optoelectronics
due to its long lifetime. On the other hand, it is notorious for being
optically inaccessible from both excitation and detection standpoints. Here, we
provide an efficient and low-loss solution to the dilemma by reintroducing
photonics bound states in the continuum (BICs) to manipulate dark excitons in
the momentum space. In a monolayer tungsten diselenide under normal incidence,
we observed a giant enhancement with an enhancement factor of ~3,100 for dark
excitons enabled by transverse magnetic BICs with intrinsic out-of-plane
electric fields. By further employing widely tunable Friedrich-Wintgen BICs, we
demonstrated highly directional emission from the dark excitons with a
divergence angle of merely 7 degrees. We found that the directional emission is
coherent at room temperature, unambiguously shown in polarization analyses and
interference measurements. Therefore, the BICs reintroduced as a momentum-space
photonic environment could be an intriguing platform to reshape and redefine
light-matter interactions in nearby quantum materials, such as low-dimensional
materials, otherwise challenging or even impossible to achieve
Super-resolution hyper-spectral imaging for the direct visualization of local bandgap heterogeneity
Optical hyperspectral imaging based on absorption and scattering of photons
at the visible and adjacent frequencies denotes one of the most informative and
inclusive characterization methods in material research. Unfortunately,
restricted by the diffraction limit of light, it is unable to resolve the
nanoscale inhomogeneity in light-matter interactions, which is diagnostic of
the local modulation in material structure and properties. Moreover, many
nanomaterials have highly anisotropic optical properties that are outstandingly
appealing yet hard to characterize through conventional optical methods.
Therefore, there has been a pressing demand in the diverse fields including
electronics, photonics, physics, and materials science to extend the optical
hyperspectral imaging into the nanometer length scale. In this work, we report
a super-resolution hyperspectral imaging technique that simultaneously measures
optical absorption and scattering spectra with the illumination from a
tungsten-halogen lamp. We demonstrated sub-5 nm spatial resolution in both
visible and near-infrared wavelengths (415 to 980 nm) for the hyperspectral
imaging of strained single-walled carbon nanotubes (SWNT) and reconstructed
true-color images to reveal the longitudinal and transverse optical
transition-induced light absorption and scattering in the SWNTs. This is the
first time transverse optical absorption in SWNTs were clearly observed
experimentally. The new technique provides rich near-field spectroscopic
information that had made it possible to analyze the spatial modulation of
band-structure along a single SWNT induced through strain engineering.Comment: 4 Figure
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