65 research outputs found
Stability of the solitary wave solutions to a coupled BBM system
In this work, we present a stability criteria for the solitary wave solutions
to a BBM system that contains coupled nonlinear terms. Using the idea by Bona,
Chen and Karakashian and exploiting the accurate point spectrum information of
the associated Schrodinger operator, we improve the stability results
previously got by Pereira.Comment: 15 page
A fast topology optimization method of damping material layer for noise reduction to elastic curved plate-cavity structure
This paper presents a fast topology optimization method of damping material layer for noise reduction to elastic curved plate (shell)-cavity structure. Using less as far as possible the damping materials reach the maximum efficiency of one's vibration or noise reduction. Energy method is employed. The way to determine the location where the damping material pasted on is to find the location where damping material’s energy will lose more. The computational model is based on a finite element discretization. Assuming pasting a small amount of damping materials on the structure has little effect on vibration mode, the relationship between energy loss of the damping material on each element and the displacement of the nodes of the plate (shell) during a period of vibration was deduced. Damping material was laid out on the element location where damping layer energy will lose most, and then the second gradually, until optimization target was achieved. Commercial finite element software was used to obtain the finite element model of complex engineering structures. Nodes information, stiffness and mass matrix were read out by Matlab subroutines. A numerical result of topology optimization of damping material layer on the curved plate-cavity structure noise reduction was presented. The topology optimization method is approximate, simple and suitable for complex engineering applications
Quantifying lens elastic properties with optical coherence elastography as a function of intraocular pressure
Normal intraocular pressure (IOP) is crucial for proper maintaining of eye-globe geometry, ocular tissue health, and visual acuity. An elevated IOP is associated with diseases such as glaucoma and uveitis. While the effects of an elevated IOP on the delicate tissues of the optic nerve head and retina are well-studied, the changes in lenticular biomechanical properties as a function of IOP are not as clear. Moreover, changes in lenticular biomechanical properties have been implicated in conditions and diseases such as presbyopia and cataract. However, measuring the biomechanical properties of the lens as it sits inside the eye-globe is a challenge, but it is necessary to correctly understand the interplay between lenticular biomechanical properties and IOP. In this work, we utilized optical coherence elastography (OCE) to measure the biomechanical properties of the porcine lens in situ
Quantifying changes in lenticular stiffness with optical coherence elastography
Maintaining a normal intraocular pressure (IOP) is important for visual health. Elevated IOPs have been implicated in many diseases, such as glaucoma and uveitis. The effects of an elevated IOP on the delicate tissues of the optic nerve head and retina are well-studied, but there is a lack of information about the effects of high IOPs on the stiffness of the crystalline lens. Changes in lenticular biomechanical properties have been implicated in diseases such as presbyopia and cataract, therefore, measuring lenticular biomechanical properties is crucial to understanding the etiology and progression of the leading causes of vision impairment. Additionally, there has been even less research focused on the effects of storage media on lenticular stiffness. Previous studies have been focused on the “gold standard” of mechanical testing on excised lenses. However, mechanical testing is invasive and destructive, and removal of the lens from the eyeglobe does not allow for properly replicating the lens environment in the eye-globe. Thus, there is a need for noninvasive measurement techniques capable of performing in situ and in vivo elastographic measurements of the lens. Here, we artificially controlled the IOP of whole porcine eye-globes (N=3). Acoustic radiation force induced low amplitude displacements (<10 µm) at the apex of the lenses, which then propagated as an elastic wave. The elastic wave propagation was detected by a phase-sensitive optical coherence elastography (PhS-OCE) system. The results show that the stiffness of the lenses increased when IOP increased from 10 mmHg IOP to 40 mmHg. Additional OCE measurements were made on excised lenses stored in various media (PBS, DMEM, and M-199) at different pHs (4-7) and at different temperatures (4°C, 22°C, and 37°C). The results show that the stiffness of the lenses increased slightly when incubated at 4°C or 22°C, but decreased when the lenses were incubated at 37°C, while lenses incubated in M-199 showed more stability in their stiffness than lenses incubated in PBS and DMEM. Moreover, the lenses stored in M-199 at a pH of 7 showed a decrease in stiffness over 24 hours, while the more acidic M-199 media caused an increase in lenticular stiffness
Comparative Transcriptional Profiling of Melatonin Synthesis and Catabolic Genes Indicates the Possible Role of Melatonin in Developmental and Stress Responses in Rice
As a well-known animal hormone, melatonin (N-acetyl-5-methoxytryptamine) is also involved in multiple plant biological processes, especially in various stress responses. Rice is one of the most important crops, and melatonin is taken in by many people everyday from rice. However, the transcriptional profiling of melatonin-related genes in rice is largely unknown. In this study, the expression patterns of 11 melatonin related genes in rice in different periods, tissues, in response to different treatments were synthetically analyzed using published microarray data. These results suggest that the melatonin-related genes may play important and dual roles in rice developmental stages. We highlight the commonly regulation of rice melatonin-related genes by abscisic acid (ABA), jasmonic acid (JA), various abiotic stresses and pathogen infection, indicating the possible role of these genes in multiple stress responses and underlying crosstalks of plant hormones, especially ABA and JA. Taken together, this study may provide insight into the association among melatonin biosynthesis and catabolic pathway, plant development and stress responses in rice. The profile analysis identified candidate genes for further functional characterization in circadian rhythm and specific stress responses
Advancing UWF-SLO Vessel Segmentation with Source-Free Active Domain Adaptation and a Novel Multi-Center Dataset
Accurate vessel segmentation in Ultra-Wide-Field Scanning Laser
Ophthalmoscopy (UWF-SLO) images is crucial for diagnosing retinal diseases.
Although recent techniques have shown encouraging outcomes in vessel
segmentation, models trained on one medical dataset often underperform on
others due to domain shifts. Meanwhile, manually labeling high-resolution
UWF-SLO images is an extremely challenging, time-consuming and expensive task.
In response, this study introduces a pioneering framework that leverages a
patch-based active domain adaptation approach. By actively recommending a few
valuable image patches by the devised Cascade Uncertainty-Predominance (CUP)
selection strategy for labeling and model-finetuning, our method significantly
improves the accuracy of UWF-SLO vessel segmentation across diverse medical
centers. In addition, we annotate and construct the first Multi-center UWF-SLO
Vessel Segmentation (MU-VS) dataset to promote this topic research, comprising
data from multiple institutions. This dataset serves as a valuable resource for
cross-center evaluation, verifying the effectiveness and robustness of our
approach. Experimental results demonstrate that our approach surpasses existing
domain adaptation and active learning methods, considerably reducing the gap
between the Upper and Lower bounds with minimal annotations, highlighting our
method's practical clinical value. We will release our dataset and code to
facilitate relevant research: https://github.com/whq-xxh/SFADA-UWF-SLO.Comment: MICCAI 2024 Early Accep
Dual-Reference Source-Free Active Domain Adaptation for Nasopharyngeal Carcinoma Tumor Segmentation across Multiple Hospitals
Nasopharyngeal carcinoma (NPC) is a prevalent and clinically significant
malignancy that predominantly impacts the head and neck area. Precise
delineation of the Gross Tumor Volume (GTV) plays a pivotal role in ensuring
effective radiotherapy for NPC. Despite recent methods that have achieved
promising results on GTV segmentation, they are still limited by lacking
carefully-annotated data and hard-to-access data from multiple hospitals in
clinical practice. Although some unsupervised domain adaptation (UDA) has been
proposed to alleviate this problem, unconditionally mapping the distribution
distorts the underlying structural information, leading to inferior
performance. To address this challenge, we devise a novel Sourece-Free Active
Domain Adaptation (SFADA) framework to facilitate domain adaptation for the GTV
segmentation task. Specifically, we design a dual reference strategy to select
domain-invariant and domain-specific representative samples from a specific
target domain for annotation and model fine-tuning without relying on
source-domain data. Our approach not only ensures data privacy but also reduces
the workload for oncologists as it just requires annotating a few
representative samples from the target domain and does not need to access the
source data. We collect a large-scale clinical dataset comprising 1057 NPC
patients from five hospitals to validate our approach. Experimental results
show that our method outperforms the UDA methods and achieves comparable
results to the fully supervised upper bound, even with few annotations,
highlighting the significant medical utility of our approach. In addition,
there is no public dataset about multi-center NPC segmentation, we will release
code and dataset for future research
Quantitative assessment of chlorine gas inhalation injury based on endoscopic OCT and spectral encoded interferometric microscope imaging with deep learning.
Chlorine exposure can cause severe airway injuries. While the acute effects of chlorine inhalation are well-documented, the structural changes resulting from the post-acute, high-level chlorine exposure remain less understood. Airway sloughing is one of the standards for doctors to evaluate the lung function. Here, we report the application of a high-resolution swept-source optical coherence tomography system to investigate the progression of injury based on airway sloughing evaluation in a chlorine inhalation rabbit model. This system employs a 1.2 mm diameter flexible fiberoptic endoscopic probe via an endotracheal tube to capture in vivo large airway anatomical changes before and as early as 30 min after acute chlorine exposure. We conducted an animal study using New Zealand white rabbits exposed to acute chlorine gas (800 ppm, 6 min) during ventilation and monitored them using optical coherence tomography (OCT) for 6 h. To measure the volume of airway sloughing induced by chlorine gas, we utilized deep learning for the segmentation task on OCT images. The results showed that the volume of chlorine induced epithelial sloughing on rabbit tracheal walls initially increased, peaked around 30 min, and then decreased. Furthermore, we utilized a spectral encoded interferometric microscopy system to study ex vivo airway cilia beating dynamics based on Doppler shift, aiding in elucidating how chlorine gas affects cilia beating function. Cilia movability and beating frequency were decreased because of the epithelium damage. This quantitative approach has the potential to enhance the diagnosis and monitoring of injuries from toxic gas inhalation and to evaluate the efficacy of antidote treatments for these injuries
Roles of NR1I3 and NR1H4 polymorphisms in the susceptibility to antituberculosis drug-induced liver injury in China: a case‒control study
ObjectiveThe pathogenesis of antituberculosis drug-induced liver injury (AT-DILI) remains largely unknown. The current investigation aimed to determine the genetic contribution of the nuclear receptor subfamily 1 Group I member 3 (NR1I3) and nuclear receptor subfamily 1 Group H member 4 (NR1H4) genes to the risk of AT-DILI in the Chinese population.MethodsA 1:4 matched case‒control study was conducted, and five single nucleotide polymorphisms (SNPs) in the NR1I3 and NR1H4 genes were detected and assessed. Utilizing a multivariate conditional logistic regression model, the effects of haplotype and genotype on the risk of AT-DILI were examined. Extended subgroup analysis was carried out based on sex. The distribution of the peak value of serum liver enzymes also compared among different genotypes.Results224 AT-DILI cases and 896 controls were included in this study. No significant difference was observed in genotypes or haplotypes frequencies between AT-DILI cases and controls. However, comparisons of liver function indicators revealed significant differences in the peak values of alanine aminotransferase (ALT), aspartate aminotransferase (AST) and total bilirubin (TBil) among patients with different genotypes of NR1H4 rs56163822 (GG vs. GT vs. TT, 27.1 U/L vs. 26.0 U/L vs. 23.0 U/L, p = 0.020; 34.0 U/L vs. 31.0 U/L vs. 30.6 U/L, p = 0.008; 15.5 μmol/L vs. 15.0 μmol/L vs. 13.7 μmol/L, p = 0.029, respectively), as well as in the peak values of ALT and AST among male patients with different genotypes of NR1H4 rs56163822 (29.0 U/L vs. 26.9 U/L vs. 22.6 U/L, p = 0.002; 34.0 U/L vs. 32.0 U/L vs. 30.5 U/L, p = 0.019, respectively).ConclusionBased on this 1:4 individual-matched case‒control study, the SNP rs56163822 in the NR1H4 gene may be linked to the susceptibility to AT-DILI in Chinese patients receiving anti-TB treatment. Further studies in larger varied populations are needed to validate our findings
SegRap2023: A Benchmark of Organs-at-Risk and Gross Tumor Volume Segmentation for Radiotherapy Planning of Nasopharyngeal Carcinoma
Radiation therapy is a primary and effective NasoPharyngeal Carcinoma (NPC)
treatment strategy. The precise delineation of Gross Tumor Volumes (GTVs) and
Organs-At-Risk (OARs) is crucial in radiation treatment, directly impacting
patient prognosis. Previously, the delineation of GTVs and OARs was performed
by experienced radiation oncologists. Recently, deep learning has achieved
promising results in many medical image segmentation tasks. However, for NPC
OARs and GTVs segmentation, few public datasets are available for model
development and evaluation. To alleviate this problem, the SegRap2023 challenge
was organized in conjunction with MICCAI2023 and presented a large-scale
benchmark for OAR and GTV segmentation with 400 Computed Tomography (CT) scans
from 200 NPC patients, each with a pair of pre-aligned non-contrast and
contrast-enhanced CT scans. The challenge's goal was to segment 45 OARs and 2
GTVs from the paired CT scans. In this paper, we detail the challenge and
analyze the solutions of all participants. The average Dice similarity
coefficient scores for all submissions ranged from 76.68\% to 86.70\%, and
70.42\% to 73.44\% for OARs and GTVs, respectively. We conclude that the
segmentation of large-size OARs is well-addressed, and more efforts are needed
for GTVs and small-size or thin-structure OARs. The benchmark will remain
publicly available here: https://segrap2023.grand-challenge.orgComment: A challenge report of SegRap2023 (organized in conjunction with
MICCAI2023
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