386 research outputs found
Revisiting Rolling Shutter Bundle Adjustment: Toward Accurate and Fast Solution
We propose a robust and fast bundle adjustment solution that estimates the
6-DoF pose of the camera and the geometry of the environment based on
measurements from a rolling shutter (RS) camera. This tackles the challenges in
the existing works, namely relying on additional sensors, high frame rate video
as input, restrictive assumptions on camera motion, readout direction, and poor
efficiency. To this end, we first investigate the influence of normalization to
the image point on RSBA performance and show its better approximation in
modelling the real 6-DoF camera motion. Then we present a novel analytical
model for the visual residual covariance, which can be used to standardize the
reprojection error during the optimization, consequently improving the overall
accuracy. More importantly, the combination of normalization and covariance
standardization weighting in RSBA (NW-RSBA) can avoid common planar degeneracy
without needing to constrain the filming manner. Besides, we propose an
acceleration strategy for NW-RSBA based on the sparsity of its Jacobian matrix
and Schur complement. The extensive synthetic and real data experiments verify
the effectiveness and efficiency of the proposed solution over the
state-of-the-art works. We also demonstrate the proposed method can be easily
implemented and plug-in famous GSSfM and GSSLAM systems as completed RSSfM and
RSSLAM solutions
DFR: Depth from Rotation by Uncalibrated Image Rectification with Latitudinal Motion Assumption
Despite the increasing prevalence of rotating-style capture (e.g.,
surveillance cameras), conventional stereo rectification techniques frequently
fail due to the rotation-dominant motion and small baseline between views. In
this paper, we tackle the challenge of performing stereo rectification for
uncalibrated rotating cameras. To that end, we propose Depth-from-Rotation
(DfR), a novel image rectification solution that analytically rectifies two
images with two-point correspondences and serves for further depth estimation.
Specifically, we model the motion of a rotating camera as the camera rotates on
a sphere with fixed latitude. The camera's optical axis lies perpendicular to
the sphere's surface. We call this latitudinal motion assumption. Then we
derive a 2-point analytical solver from directly computing the rectified
transformations on the two images. We also present a self-adaptive strategy to
reduce the geometric distortion after rectification. Extensive synthetic and
real data experiments demonstrate that the proposed method outperforms existing
works in effectiveness and efficiency by a significant margin
Detection and Genetic Environment of Pleuromutilin-Lincosamide-Streptogramin A Resistance Genes in Staphylococci Isolated from Pets
Increasing emergence of staphylococci resistant to pleuromutilins,
lincosamides, and streptogramin A (PLSA) and isolated from humans and pets is
a growing public health concern worldwide. Currently, there was only one
published study regarding one of the PLSA genes, vga(A) detected in
staphylococci isolated from cat. In this study, eleven pleuromutilin-resistant
staphylococci from pets and two from their owners were isolated and further
characterized for their antimicrobial susceptibilities, plasmid profiles,
genotypes, and genetic context of the PLSA resistance genes. The gene sal(A)
identified in 11 staphylococcal isolates was found for the first time in
Staphylococcus haemolyticus, Staphylococcus epidermidis, and Staphylococcus
xylosus. Moreover, these 11 isolates shared the identical regions flanking the
sal(A) gene located in the chromosomal DNA. Two S. haemolyticus isolates from
a cat and its owner carried similar vga(A)LC plasmids and displayed
indistinguishable PFGE patterns. A novel chromosomal multidrug resistance
genomic island (MDRGI) containing 13 resistance genes, including lsa(E), was
firstly identified in S. epidermidis. In addition, vga(A)LC, sal(A), and
lsa(E) were for the first time identified in staphylococcal isolates
originating from pet animals. The plasmids, chromosomal DNA region, and MDRGI
associated with the PLSA resistance genes vga(A), vga(A)LC, sal(A), and lsa(E)
are present in staphylococci isolated from pets and humans and present
significant challenges for the clinical management of infections by limiting
therapeutic options
Stress background and rock fractures revealed by ultrasonic borehole television in the Fankou Lead-Zinc Mine
The stress background and rock fractures are essential factors affecting the stability of mines. In order to better understand the in situ stress background and rock fractures in the Guangdong Fankou Mine, we use ultrasonic borehole television scanning to measure rock fractures. The results indicate that rock fractures are intensively distributed at depths of −360 m to −450 m below the surface, suggesting the effect of intensive mining activities. The present maximum horizontal principal stress direction is NWW, which is consistent with the regional tectonic stress field direction. Systematic measurement of rock fractures is fundamental for further three-dimensional geological modeling and is significant for mining engineering
Grassland health assessment based on indicators monitored by UAVs: a case study at a household scale
Grassland health assessment (GHA) is a bridge of study and management of grassland ecosystem. However, there is no standardized quantitative indicators and long-term monitor methods for GHA at a large scale, which may hinder theoretical study and practical application of GHA. In this study, along with previous concept and practices (i.e., CVOR, the integrated indexes of condition, vigor, organization and resilience), we proposed an assessment system based on the indicators monitored by unmanned aerial vehicles (UAVs)-UAVCVOR, and tested the feasibility of UAVCVOR at typical household pastures on the Qinghai-Tibetan Plateau, China. Our findings show that: (1) the key indicators of GHA could be measured directly or represented by the relative counterpart indicators that monitored by UAVs, (2) there was a significantly linear relationship between CVOR estimated by field- and UAV-based data, and (3) the CVOR decreased along with the increasing grazing intensity nonlinearly, and there are similar tendencies of CVOR that estimated by the two methods. These findings suggest that UAVs is suitable for GHA efficiently and correctly, which will be useful for the protection and sustainable management of grasslands
Apigenin Combined With Gefitinib Blocks Autophagy Flux and Induces Apoptotic Cell Death Through Inhibition of HIF-1α, c-Myc, p-EGFR, and Glucose Metabolism in EGFR L858R+T790M-Mutated H1975 Cells
Cancer cells are characterized by abnormally increased glucose uptake and active bio-energy and biosynthesis to support the proliferation, metastasis, and drug resistant survival. We examined the therapeutic value of the combination of apigenin (a natural small-molecule inhibitor of Glut1 belonging to the flavonoid family) and gefitinib on epidermal growth factor receptor (EGFR)-resistant mutant non-small cell lung cancer, to notably damage glucose utilization and thus suppress cell growth and malignant behavior. Here, we demonstrate that apigenin combined with gefitinib inhibits multiple oncogenic drivers such as c-Myc, HIF-1α, and EGFR, reduces Gluts and MCT1 protein expression, and inactivates the 5′ adenosine monophosphate-activated protein kinase (AMPK) signaling, which regulates glucose uptake and maintains energy metabolism, leading to impaired energy utilization in EGFR L858R-T790M-mutated H1975 lung cancer cells. H1975 cells exhibit dysregulated metabolism and apoptotic cell death following treatment with apigenin + gefitinib. Therefore, the combined apigenin + gefitinib treatment presents an attractive strategy as alternative treatment for the acquired resistance to EGFR-TKIs in NSCLC
Insight-HXMT on-orbit thermal control status and thermal deformation impact analysis
Purpose: The Hard X-ray Modulation Telescope is China's first X-ray astronomy
satellite launched on June 15th, 2017, dubbed Insight-HXMT. Active and passive
thermal control measures are employed to keep devices at suitable temperatures.
In this paper, we analyzed the on-orbit thermal monitoring data of the first 5
years and investigated the effect of thermal deformation on the point spread
function (PSF) of the telescopes.
Methods: We examined the data of the on-orbit temperatures measured using 157
thermistors placed on the collimators, detectors and their support structures
and compared the results with the thermal control requirements. The thermal
deformation was evaluated by the relative orientation of the two star sensors
installed on the main support structure. its effect was estimated with
evolution of the PSF obtained with calibration scanning observations of the
Crab nebula.
Conclusion: The on-orbit temperatures met the thermal control requirements
thus far, and the effect of thermal deformation on the PSF was negligible after
the on-orbit pointing calibration.Comment: 25 pages, 35 figures, submitte
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