78 research outputs found
Asynchronous Collaborative Autoscanning with Mode Switching for Multi-Robot Scene Reconstruction
When conducting autonomous scanning for the online reconstruction of unknown
indoor environments, robots have to be competent at exploring scene structure
and reconstructing objects with high quality. Our key observation is that
different tasks demand specialized scanning properties of robots: rapid moving
speed and far vision for global exploration and slow moving speed and narrow
vision for local object reconstruction, which are referred as two different
scanning modes: explorer and reconstructor, respectively. When requiring
multiple robots to collaborate for efficient exploration and fine-grained
reconstruction, the questions on when to generate and how to assign those tasks
should be carefully answered. Therefore, we propose a novel asynchronous
collaborative autoscanning method with mode switching, which generates two
kinds of scanning tasks with associated scanning modes, i.e., exploration task
with explorer mode and reconstruction task with reconstructor mode, and assign
them to the robots to execute in an asynchronous collaborative manner to highly
boost the scanning efficiency and reconstruction quality. The task assignment
is optimized by solving a modified Multi-Depot Multiple Traveling Salesman
Problem (MDMTSP). Moreover, to further enhance the collaboration and increase
the efficiency, we propose a task-flow model that actives the task generation
and assignment process immediately when any of the robots finish all its tasks
with no need to wait for all other robots to complete the tasks assigned in the
previous iteration. Extensive experiments have been conducted to show the
importance of each key component of our method and the superiority over
previous methods in scanning efficiency and reconstruction quality.Comment: 13pages, 12 figures, Conference: SIGGRAPH Asia 202
SelfOdom: Self-supervised Egomotion and Depth Learning via Bi-directional Coarse-to-Fine Scale Recovery
Accurately perceiving location and scene is crucial for autonomous driving
and mobile robots. Recent advances in deep learning have made it possible to
learn egomotion and depth from monocular images in a self-supervised manner,
without requiring highly precise labels to train the networks. However,
monocular vision methods suffer from a limitation known as scale-ambiguity,
which restricts their application when absolute-scale is necessary. To address
this, we propose SelfOdom, a self-supervised dual-network framework that can
robustly and consistently learn and generate pose and depth estimates in global
scale from monocular images. In particular, we introduce a novel coarse-to-fine
training strategy that enables the metric scale to be recovered in a two-stage
process. Furthermore, SelfOdom is flexible and can incorporate inertial data
with images, which improves its robustness in challenging scenarios, using an
attention-based fusion module. Our model excels in both normal and challenging
lighting conditions, including difficult night scenes. Extensive experiments on
public datasets have demonstrated that SelfOdom outperforms representative
traditional and learning-based VO and VIO models.Comment: 14 pages, 8 figures, in submissio
DevNet: Self-supervised Monocular Depth Learning via Density Volume Construction
Self-supervised depth learning from monocular images normally relies on the
2D pixel-wise photometric relation between temporally adjacent image frames.
However, they neither fully exploit the 3D point-wise geometric
correspondences, nor effectively tackle the ambiguities in the photometric
warping caused by occlusions or illumination inconsistency. To address these
problems, this work proposes Density Volume Construction Network (DevNet), a
novel self-supervised monocular depth learning framework, that can consider 3D
spatial information, and exploit stronger geometric constraints among adjacent
camera frustums. Instead of directly regressing the pixel value from a single
image, our DevNet divides the camera frustum into multiple parallel planes and
predicts the pointwise occlusion probability density on each plane. The final
depth map is generated by integrating the density along corresponding rays.
During the training process, novel regularization strategies and loss functions
are introduced to mitigate photometric ambiguities and overfitting. Without
obviously enlarging model parameters size or running time, DevNet outperforms
several representative baselines on both the KITTI-2015 outdoor dataset and
NYU-V2 indoor dataset. In particular, the root-mean-square-deviation is reduced
by around 4% with DevNet on both KITTI-2015 and NYU-V2 in the task of depth
estimation. Code is available at https://github.com/gitkaichenzhou/DevNet.Comment: Accepted by European Conference on Computer Vision 2022 (ECCV2022
High hydrostatic pressure harnesses the biosynthesis of secondary metabolites via the regulation of polyketide synthesis genes of hadal sediment-derived fungi
Deep-sea fungi have evolved extreme environmental adaptation and possess huge biosynthetic potential of bioactive compounds. However, not much is known about the biosynthesis and regulation of secondary metabolites of deep-sea fungi under extreme environments. Here, we presented the isolation of 15 individual fungal strains from the sediments of the Mariana Trench, which were identified by internal transcribed spacer (ITS) sequence analysis as belonging to 8 different fungal species. High hydrostatic pressure (HHP) assays were performed to identify the piezo-tolerance of the hadal fungi. Among these fungi, Aspergillus sydowii SYX6 was selected as the representative due to the excellent tolerance of HHP and biosynthetic potential of antimicrobial compounds. Vegetative growth and sporulation of A. sydowii SYX6 were affected by HHP. Natural product analysis with different pressure conditions was also performed. Based on bioactivity-guided fractionation, diorcinol was purified and characterized as the bioactive compound, showing significant antimicrobial and antitumor activity. The core functional gene associated with the biosynthetic gene cluster (BGC) of diorcinol was identified in A. sydowii SYX6, named as AspksD. The expression of AspksD was apparently regulated by the HHP treatment, correlated with the regulation of diorcinol production. Based on the effect of the HHP tested here, high pressure affected the fungal development and metabolite production, as well as the expression level of biosynthetic genes which revealed the adaptive relationship between the metabolic pathway and the high-pressure environment at the molecular level
New insights into bacterial mechanisms and potential intestinal epithelial cell therapeutic targets of inflammatory bowel disease
The global incidence of inflammatory bowel disease (IBD) has increased rapidly in recent years, but its exact etiology remains unclear. In the past decade, IBD has been reported to be associated with dysbiosis of gut microbiota. Although not yet proven to be a cause or consequence of IBD, the common hypothesis is that at least some alterations in the microbiome are protective or pathogenic. Furthermore, intestinal epithelial cells (IECs) serve as a protective physical barrier for gut microbiota, essential for maintaining intestinal homeostasis and actively contributes to the mucosal immune system. Thus, dysregulation within the intestinal epithelium increases intestinal permeability, promotes the entry of bacteria, toxins, and macromolecules, and disrupts intestinal immune homeostasis, all of which are associated with the clinical course of IBD. This article presents a selective overview of recent studies on bacterial mechanisms that may be protective or promotive of IBD in biological models. Moreover, we summarize and discuss the recent discovery of key modulators and signaling pathways in the IECs that could serve as potential IBD therapeutic targets. Understanding the role of the IECs in the pathogenesis of IBD may help improve the understanding of the inflammatory process and the identification of potential therapeutic targets to help ameliorate this increasingly common disease
Deciphering the phase transition-induced ultrahigh piezoresponse in (K,Na)NbO-based piezoceramics
Here, we introduce phase change mechanisms in lead-free piezoceramics as a strategy to utilize attendant volume change for harvesting large electrostrain. In the newly developed (K,Na)NbO solid-solution at the polymorphic phase boundary we combine atomic mapping of the local polar vector with in situ synchrotron X-ray diffraction and density functional theory to uncover the phase change and interpret its underlying nature. We demonstrate that an electric field-induced phase transition between orthorhombic and tetragonal phases triggers a dramatic volume change and contributes to a huge effective piezoelectric coefficient of 1250 pm V along specific crystallographic directions. The existence of the phase transition is validated by a significant volume change evidenced by the simultaneous recording of macroscopic longitudinal and transverse strain. The principle of using phase transition to promote electrostrain provides broader design flexibility in the development of high-performance piezoelectric materials and opens the door for the discovery of high-performance future functional oxides
First description of the male of Oecobius przewalskyi Hu & Li, 1987 (Araneae, Oecobiidae) from Shigatse City, Tibet, China
With 90 described species, the genus Oecobius Lucas, 1846 is the largest genus of the family Oecobiidae Blackwall, 1862, five of which are known from China. Since Oceobius przewalskyi was described by Hu & Li in 1987, no males of this species have ever been reported.The male of Oceobius przewalskyi is described for the first time, based on the specimens collected in Tibet Autonomous Region. Morphological description and illustrations are given
Research on Existing Problems and Improvement Measures of Fabricated Composite Wallboard
In recent years, fabricated composite wall panels have been widely used in building materials markets at home and abroad, and their main advantages are convenient construction, low energy consumption, and heat and sound insulation. However, fabricated composite wall panels also have some common problems in practical applications, such as large dead weight, weak seismic performance, prone to cracks, and failing to meet the higher energy-saving requirements of thermal insulation external walls. This article analyzes the board material and overall structure of the fabricated composite wallboard, proposes corresponding solutions to make up for its weakness in some performance, and gives the specific construction process and accuracy requirements
The practical clinical role of machine learning models with different algorithms in predicting prostate cancer local recurrence after radical prostatectomy
Abstract Background The detection of local recurrence for prostate cancer (PCa) patients following radical prostatectomy (RP) is challenging and can influence the treatment plan. Our aim was to construct and verify machine learning models with three different algorithms based on post-operative mpMRI for predicting local recurrence of PCa after RP and explore their potential clinical value compared with the Prostate Imaging for Recurrence Reporting (PI-RR) score of expert-level radiologists. Methods A total of 176 patients were retrospectively enrolled and randomly divided into training (n = 123) and testing (n = 53) sets. The PI-RR assessments were performed by two expert-level radiologists with access to the operative histopathological and pre-surgical clinical results. The radiomics models to predict local recurrence were built by utilizing three different algorithms (i.e., support vector machine [SVM], linear discriminant analysis [LDA], and logistic regression-least absolute shrinkage and selection operator [LR-LASSO]). The combined model integrating radiomics features and PI-RR score was developed using the most effective classifier. The classification performances of the proposed models were assessed by receiver operating characteristic (ROC) curve analysis. Results There were no significant differences between the training and testing sets concerning age, prostate-specific antigen (PSA), Gleason score, T-stage, seminal vesicle invasion (SVI), perineural invasion (PNI), and positive surgical margins (PSM). The radiomics model based on LR-LASSO exhibited superior performance than other radiomics models, with an AUC of 0.858 in the testing set; the PI-RR yielded an AUC of 0.833, and there was no significant difference between the best radiomics model and the PI-RR score. The combined model achieved the best predictive performance with an AUC of 0.924, and a significant difference was observed between the combined model and PI-RR score. Conclusions Our radiomics model is an effective tool to predict PCa local recurrence after RP. By integrating radiomics features with the PI-RR score, our combined model exhibited significantly better predictive performance of local recurrence than expert-level radiologists’ PI-RR assessment
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