75 research outputs found
High order entropy stable schemes for the quasi-one-dimensional shallow water and compressible Euler equations
High order schemes are known to be unstable in the presence of shock
discontinuities or under-resolved solution features for nonlinear conservation
laws. Entropy stable schemes address this instability by ensuring that
physically relevant solutions satisfy a semi-discrete entropy inequality
independently of discretization parameters. This work extends high order
entropy stable schemes to the quasi-1D shallow water equations and the quasi-1D
compressible Euler equations, which model one-dimensional flows through
channels or nozzles with varying width.
We introduce new non-symmetric entropy conservative finite volume fluxes for
both sets of quasi-1D equations, as well as a generalization of the entropy
conservation condition to non-symmetric fluxes. When combined with an entropy
stable interface flux, the resulting schemes are high order accurate,
conservative, and semi-discretely entropy stable. For the quasi-1D shallow
water equations, the resulting schemes are also well-balanced
Distilled Visual and Robot Kinematics Embeddings for Metric Depth Estimation in Monocular Scene Reconstruction
Estimating precise metric depth and scene reconstruction from monocular
endoscopy is a fundamental task for surgical navigation in robotic surgery.
However, traditional stereo matching adopts binocular images to perceive the
depth information, which is difficult to transfer to the soft robotics-based
surgical systems due to the use of monocular endoscopy. In this paper, we
present a novel framework that combines robot kinematics and monocular
endoscope images with deep unsupervised learning into a single network for
metric depth estimation and then achieve 3D reconstruction of complex anatomy.
Specifically, we first obtain the relative depth maps of surgical scenes by
leveraging a brightness-aware monocular depth estimation method. Then, the
corresponding endoscope poses are computed based on non-linear optimization of
geometric and photometric reprojection residuals. Afterwards, we develop a
Depth-driven Sliding Optimization (DDSO) algorithm to extract the scaling
coefficient from kinematics and calculated poses offline. By coupling the
metric scale and relative depth data, we form a robust ensemble that represents
the metric and consistent depth. Next, we treat the ensemble as supervisory
labels to train a metric depth estimation network for surgeries (i.e.,
MetricDepthS-Net) that distills the embeddings from the robot kinematics,
endoscopic videos, and poses. With accurate metric depth estimation, we utilize
a dense visual reconstruction method to recover the 3D structure of the whole
surgical site. We have extensively evaluated the proposed framework on public
SCARED and achieved comparable performance with stereo-based depth estimation
methods. Our results demonstrate the feasibility of the proposed approach to
recover the metric depth and 3D structure with monocular inputs
Stereo Dense Scene Reconstruction and Accurate Localization for Learning-Based Navigation of Laparoscope in Minimally Invasive Surgery
Objective: The computation of anatomical information and laparoscope position
is a fundamental block of surgical navigation in Minimally Invasive Surgery
(MIS). Recovering a dense 3D structure of surgical scene using visual cues
remains a challenge, and the online laparoscopic tracking primarily relies on
external sensors, which increases system complexity. Methods: Here, we propose
a learning-driven framework, in which an image-guided laparoscopic localization
with 3D reconstructions of complex anatomical structures is obtained. To
reconstruct the 3D structure of the whole surgical environment, we first
fine-tune a learning-based stereoscopic depth perception method, which is
robust to the texture-less and variant soft tissues, for depth estimation.
Then, we develop a dense visual reconstruction algorithm to represent the scene
by surfels, estimate the laparoscope poses and fuse the depth maps into a
unified reference coordinate for tissue reconstruction. To estimate poses of
new laparoscope views, we achieve a coarse-to-fine localization method, which
incorporates our reconstructed 3D model. Results: We evaluate the
reconstruction method and the localization module on three datasets, namely,
the stereo correspondence and reconstruction of endoscopic data (SCARED), the
ex-vivo phantom and tissue data collected with Universal Robot (UR) and Karl
Storz Laparoscope, and the in-vivo DaVinci robotic surgery dataset, where the
reconstructed 3D structures have rich details of surface texture with an
accuracy error under 1.71 mm and the localization module can accurately track
the laparoscope with only images as input. Conclusions: Experimental results
demonstrate the superior performance of the proposed method in 3D anatomy
reconstruction and laparoscopic localization. Significance: The proposed
framework can be potentially extended to the current surgical navigation
system
Baseline elevated Lp-PLA2 is associated with increased risk for re-stenosis after stent placement
BACKGROUND: Lipoprotein associated phospholipase A2 (Lp-PLA2) is a novel biomarker for cardiovascular risk prediction. Whether increased Lp-PLA2 level is associated with re-stenosis after stent-placement is unclear. METHODS: Totally 326 participants eligible for stent-placement were enrolled and divided into two groups according to baseline Lp-PLA2 levels (named normal and elevated groups). Baseline characteristics and clinical outcomes were compared between normal and elevated groups. The relationships between Lp-PLA2 and other risk factors with re-stenosis were evaluated. RESULTS: Only the between-group difference of Lp-PLA2 was significant (123.2 ± 33.6 ng/mL vs 336.8 ± 85.4 ng/mL, P < 0.001) while other demographic and clinical characteristics between these two groups were comparable. Approximately 55.1% and 58.5% of participants in normal and elevated groups presented with acute coronary syndrome, and the percentage of tri-vessels stenoses was significantly higher in elevated group (40.8% vs 32.1%, P = 0.016). Nearly 96.0% and 94.0% of participants in normal and elevated Lp-PLA2 groups were placed with drug-eluting stents, and the others were with bare-metal stents. After 1 year’s follow-up, the incidence of clinical end-points was comparable (13.3% vs 15.4%, P = 0.172). Nevertheless, the incidence of re-stenosis was marginally higher in elevated Lp-PLA2 group (8.5% versus 4.6%, P = 0.047). With multivariate analysis, after adjustment for other risk factors, Lp-PLA2 remained an independent predictor for re-stenosis with a hazard ratio of 1.140. No synergistic effect between Lp-PLA2 and other risk factors for re-stenosis was found. CONCLUSION: Increased Lp-PLA2 level is associated with an increased risk of re-stenosis. Lp-PLA2 assessment may be useful in predicting subjects who are at increased risk for re-stenosis
Expression and purification of soluble single-chain Fv against human fibroblast growth factor receptor 3 fused with Sumo tag in Escherichia coli
Background: Overexpression or mutated activation of Fibroblast growth
factor receptor 3 (FGFR3) is involved in the pathogenesis of many
tumors. More and more studies focus on the potential usage of
therapeutic antibodies against FGFR3. Results: In this study, a novel
single-chain Fv (ScFv) against FGFR3 was prepared and characterized. To
achieve the soluble expression, ScFv was fused with Sumo (Small
ubiquitin-related modifier) by polymerase chain reaction (PCR), and
cloned into pET-20b. The recombinant bacteria were induced by 0.5 mM
Isopropyl-\u3b2-D-thiogalactopyranoside (IPTG) for 16 h at 20\ub0C,
and the supernatant liquid of Sumo-ScFv was harvested and purified by
Ni-NTA chromatography. After being cleaved by the Sumo protease, the
recombinant ScFv was released from the fusion protein, and further
purified by Ni-NTA chromatography. The purity of ScFv was shown to be
higher than 95% and their yield reached 4 mg per liter of bacterial
culture. In vitro data showed that ScFv can significantly attenuate
FGF9-induced phosphorylation of FGFR3. Conclusion: We provide a novel
method to produce soluble expression and bioactive functions of ScFv in
Escherichia coli
The Serine/Threonine-Protein Phosphatase 1 From Haemonchus contortus Is Actively Involved in Suppressive Regulatory Roles on Immune Functions of Goat Peripheral Blood Mononuclear Cells
Serine/threonine-protein phosphatases (STPs), as integral constituents of parasitic excretory/secretory proteins, are assumed to be released during the host–parasite interactions. However, knowledge about these phosphatases and their immunoregulatory and immune protective efficiencies with host peripheral blood mononuclear cells (PBMCs) is scant. In this study, an open reading frame of STP from Haemonchus contortus designated as HcSTP-1 was amplified and cloned using reverse-transcription-polymerase chain reaction (RT-PCR) method. The 951-bp nucleotides sequence was encoded to a protein of 316 amino acid residues, conserved in characteristics motifs GDXHG, GDYVDRG, GNHE, HGG, RG, and H. The HcSTP-1 protein was detected at approximately 35 kDa as recombinant protein fused in an expression vector system and resolved on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Immunohistochemically, HcSTP-1 was found to be localized in both male and female adult worm sections. Using immunofluorescence assay, the binding activity of rHcSTP-1 was confirmed on surface of goat PBMCs, which resulted in expression of multiple cytokines and various immunoregulatory activities in vitro. The RT-PCR results showed that mRNA level of interleukin-2, TGF-β1, IFN-γ, and IL-17 (with 10 µg/ml) was upregulated and IL-10 was decreased. However, IL-6 showed no change after PBMCs incubated with rHcSTP-1 protein. Further functional analysis showed that migratory activity of cells, intracellular nitrite production (NO), and apoptotic efficiency of PBMCs were elevated at significant level, whereas the proliferation of goat PBMCs and monocytes-associated major histocompatibility complex (MHC)-I and MHC-II expressions were decreased significantly at concentration-dependent fashion. Our results showed that the HcSTP-1 protein engaged in vital suppressive regulatory roles on host immune cells, which might represent a potential molecular target for controlling H. contortus infection in future
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