276 research outputs found
Multimodal Short Video Rumor Detection System Based on Contrastive Learning
With short video platforms becoming one of the important channels for news
sharing, major short video platforms in China have gradually become new
breeding grounds for fake news. However, it is not easy to distinguish short
video rumors due to the great amount of information and features contained in
short videos, as well as the serious homogenization and similarity of features
among videos. In order to mitigate the spread of short video rumors, our group
decides to detect short video rumors by constructing multimodal feature fusion
and introducing external knowledge after considering the advantages and
disadvantages of each algorithm. The ideas of detection are as follows: (1)
dataset creation: to build a short video dataset with multiple features; (2)
multimodal rumor detection model: firstly, we use TSN (Temporal Segment
Networks) video coding model to extract video features; then, we use OCR
(Optical Character Recognition) and ASR (Automatic Character Recognition) to
extract video features. Recognition) and ASR (Automatic Speech Recognition)
fusion to extract text, and then use the BERT model to fuse text features with
video features (3) Finally, use contrast learning to achieve distinction: first
crawl external knowledge, then use the vector database to achieve the
introduction of external knowledge and the final structure of the
classification output. Our research process is always oriented to practical
needs, and the related knowledge results will play an important role in many
practical scenarios such as short video rumor identification and social opinion
control
A Theoretical Analysis of Efficiency Constrained Utility-Privacy Bi-Objective Optimization in Federated Learning
Federated learning (FL) enables multiple clients to collaboratively learn a
shared model without sharing their individual data. Concerns about utility,
privacy, and training efficiency in FL have garnered significant research
attention. Differential privacy has emerged as a prevalent technique in FL,
safeguarding the privacy of individual user data while impacting utility and
training efficiency. Within Differential Privacy Federated Learning (DPFL),
previous studies have primarily focused on the utility-privacy trade-off,
neglecting training efficiency, which is crucial for timely completion.
Moreover, differential privacy achieves privacy by introducing controlled
randomness (noise) on selected clients in each communication round. Previous
work has mainly examined the impact of noise level () and communication
rounds () on the privacy-utility dynamic, overlooking other influential
factors like the sample ratio (, the proportion of selected clients). This
paper systematically formulates an efficiency-constrained utility-privacy
bi-objective optimization problem in DPFL, focusing on , , and .
We provide a comprehensive theoretical analysis, yielding analytical solutions
for the Pareto front. Extensive empirical experiments verify the validity and
efficacy of our analysis, offering valuable guidance for low-cost parameter
design in DPFL
EVD Surgical Guidance with Retro-Reflective Tool Tracking and Spatial Reconstruction using Head-Mounted Augmented Reality Device
Augmented Reality (AR) has been used to facilitate surgical guidance during
External Ventricular Drain (EVD) surgery, reducing the risks of misplacement in
manual operations. During this procedure, the pivotal challenge is the accurate
estimation of spatial relationship between pre-operative images and actual
patient anatomy in AR environment. In this research, we propose a novel
framework utilizing Time of Flight (ToF) depth sensors integrated in
commercially available AR Head Mounted Devices (HMD) for precise EVD surgical
guidance. As previous studies have proven depth errors for ToF sensors, we
first conducted a comprehensive assessment for the properties of this error on
AR-HMDs. Subsequently, a depth error model and patient-specific model parameter
identification method, is introduced for accurate surface information. After
that, a tracking procedure combining retro-reflective markers and point clouds
is proposed for accurate head tracking, where head surface is reconstructed
using ToF sensor data for spatial registration, avoiding fixing tracking
targets rigidly on the patient's cranium. Firstly, ToF
sensor depth value error was revealed on human skin, indicating the
significance of depth correction. Our results showed that the ToF sensor depth
error was reduced by over using proposed depth correction method on head
phantoms in different materials. Meanwhile, the head surface reconstructed with
corrected depth data achieved sub-millimeter accuracy. Experiment on a sheep
head revealed reconstruction error. Furthermore, a user study was
conducted for the performance of proposed framework in simulated EVD surgery,
where 5 surgeons performed 9 k-wire injections on a head phantom with virtual
guidance. Results of this study revealed translational
accuracy and orientational accuracy
Effects of Impeller Diameter on High-Speed Rescue Pump
Impeller diameter is a crucial design parameter of high-speed rescue pumps because it affects the performance and inner flow characteristics of these pumps. In this study, a pump with an impeller diameter of 248 mm was modeled and its performance was tested. Numerical simulations were conducted under steady and unsteady states, in which the sizes of the impeller diameters were designated as 248 mm (original), 235.6 mm (5% trimmed), 223.2 mm (10% trimmed), and 210.8 mm (15% trimmed). ANSYS software was used to test the shear stress transport (SST k-ω) of the four models, and results agreed well with experimental data. Diameter size affected impeller characteristics in both steady and unsteady states. Subsequently, the differences in performance, hydraulic loss, pressure pulsation, and radial force of the impellers were evaluated. In the performance test, the head and efficiency of the pump decreased as impeller diameter was reduced. The result trends are in accordance with the trim law within the acceptable error range. In terms of hydraulic loss, the impeller and diffuser vane components presented opposite trends with flow rate increase. Finally, in terms of pressure pulsation and radial force, the amplitude diminished while periodicity improved as impeller diameter decreased
Knockout of the S-acyltransferase Gene, PbPAT14, Confers the Dwarf Yellowing Phenotype in First Generation Pear by ABA Accumulation.
The development of dwarf fruit trees with smaller and compact characteristics leads to significantly increased fruit production, which is a major objective of pear (Pyrus bretschneideri) breeding. We identified the S-acylation activity of PbPAT14, an S-acyltransferase gene related to plant development, using a yeast (Saccharomyces cerevisiae) complementation assay, and also PbPAT14 could rescue the growth defect of the Arabidopsis mutant atpat14. We further studied the function of PbPAT14 by designing three guide RNAs for PbPAT14 to use in the CRISPR/Cas9 system. We obtained 22 positive transgenic pear lines via Agrobacterium-mediated transformation using cotyledons from seeds of Pyrus betulifolia ('Duli'). Six of these lines exhibited the dwarf yellowing phenotype and were homozygous mutations according to sequencing analysis. Ultrastructure analysis suggested that this dwarfism was manifested by shorter, thinner stems due to a reduction in cell number. A higher level of endogenous abscisic acid (ABA) and a higher transcript level of the ABA pathway genes in the mutant lines revealed that the PbPAT14 function was related to the ABA pathway. Overall, our experimental results increase the understanding of how PATs function in plants and help elucidate the mechanism of plant dwarfism
Down-regulation of microRNA-23b aggravates LPS-induced inflammatory injury in chondrogenic ATDC5 cells by targeting PDCD4
Objective(s): Osteoarthritis (OA), characterized by degradation of articular cartilage, is a leading cause of disability. As the only cell type present in cartilage, chondrocytes play curial roles in the progression of OA. In our study, we aimed to explore the roles of miR-23b in the lipopolysaccharide (LPS)-induced inflammatory injury. Materials and Methods: LPS-induced cell injury of ATDC5 cells was evaluated by the loss of cell viability, enhancement of cell apoptosis, alteration of apoptosis-associated proteins, and release of inflammatory cytokines. Then, miR-23b level after LPS treatment was assessed by qRT-PCR. Next, the effects of aberrantly expressed miR-23b on the LPS-induced inflammatory injury were explored. The possible target genes of miR-23b were virtually screened by informatics and verified by luciferase assay. Subsequently, whether miR-23b functioned through regulating the target gene was validated. The involved signaling pathways were investigated finally.Results: Cell viability was decreased but cell apoptosis, as well as release of inflammatory cytokines, was enhanced by LPS treatment. MiR-23b was down-regulated by LPS and its overexpression alleviated LPS-induced inflammatory injury. PDCD4, negatively regulated by miR-23b expression, was verified as a target gene of miR-23b. Following experiments showed miR-23b alleviated LPS-induced cell injury through down-regulating PDCD4 expression. Phosphorylated levels of key kinases in the NF-κB pathway, as well as expressions of key kinases in the Notch pathways, were increased by PDCD4 overexpression.Conclusion: MiR-23b was down-regulated after LPS treatment, and its overexpression ameliorated LPS-induced inflammatory injury in ATDC5 cells by targeting PDCD4, which could activate the NF-κB/Notch pathways
The role of circadian clock in astrocytes: From cellular functions to ischemic stroke therapeutic targets
Accumulating evidence suggests that astrocytes, the abundant cell type in the central nervous system (CNS), play a critical role in maintaining the immune response after cerebral infarction, regulating the blood-brain barrier (BBB), providing nutrients to the neurons, and reuptake of glutamate. The circadian clock is an endogenous timing system that controls and optimizes biological processes. The central circadian clock and the peripheral clock are consistent, controlled by various circadian components, and participate in the pathophysiological process of astrocytes. Existing evidence shows that circadian rhythm controls the regulation of inflammatory responses by astrocytes in ischemic stroke (IS), regulates the repair of the BBB, and plays an essential role in a series of pathological processes such as neurotoxicity and neuroprotection. In this review, we highlight the importance of astrocytes in IS and discuss the potential role of the circadian clock in influencing astrocyte pathophysiology. A comprehensive understanding of the ability of the circadian clock to regulate astrocytes after stroke will improve our ability to predict the targets and biological functions of the circadian clock and gain insight into the basis of its intervention mechanism
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