Publications by authors named "Yun Hui Liu"

Visualizing surgical scenes is crucial for revealing internal anatomical structures during minimally invasive procedures. Novel View Synthesis is a vital technique that offers geometry and appearance reconstruction, enhancing understanding, planning, and decision-making in surgical scenes. Despite the impressive achievements of Neural Radiance Field (NeRF), its direct application to surgical scenes produces unsatisfying results due to two challenges: endoscopic sparse views and significant photometric inconsistencies.

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  • * A study in 22 apple orchards in Beijing examined the relationship between wild bee diversity and various flowering plant traits during the flowering season in 2019.
  • * Findings revealed a total of 3517 wild bees from 49 species, with diversity positively linked to the richness of flower colors and types, emphasizing the need for planting diverse nectar-producing plants to support pollinator habitats.
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Estimating the rigid transformation with 6 degrees of freedom based on a putative 3D correspondence set is a crucial procedure in point cloud registration. Existing correspondence identification methods usually lead to large outlier ratios (>95% is common), underscoring the significance of robust registration methods. Many researchers turn to parameter search-based strategies (e.

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  • The article introduces a new data-driven approach to control the 3-D shape of continuum and soft robots using feedback from proprioceptive sensors, which is essential for their autonomous operation in tasks like surgery.
  • One key challenge addressed is the complex modeling of these robots, particularly soft ones with varying stiffness, for which the proposed learning-based adaptive shape controller provides real-time adjustments without needing prior data.
  • Experimental results from two different types of robots, including a robotic-assisted colonoscope, confirm the method's effectiveness, adaptability, and performance in diverse, unstructured settings.
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Background: Previous studies have demonstrated that natural killer (NK) cells migrated into the liver from peripheral organs and exerted cytotoxic effects on hepatocytes in virus-induced liver failure.

Aim: This study aimed to investigate the potential therapeutic role of chemokine receptors in the migration of NK cells in a murine hepatitis  virus strain 3 (MHV-3)-induced fulminant hepatic failure (MHV-3-FHF) model and its mechanism.

Results: By gene array analysis, chemokine (C-C motif) receptor 5 (CCR5) was found to have remarkably elevated expression levels in hepatic NK cells after MHV-3 infection.

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Manhattan and Atlanta worlds hold for the structured scenes with only vertical and horizontal dominant directions (DDs). To describe the scenes with additional sloping DDs, a mixture of independent Manhattan worlds seems plausible, but may lead to unaligned and unrelated DDs. By contrast, we propose a novel structural model called Hong Kong world.

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  • A new uterine manipulation robot is designed to improve efficiency and safety during minimally invasive gynecologic surgery by replacing manual techniques with robotic assistance.
  • The robot features a compact design with a unique 3-DoF remote center of motion (RCM) mechanism and a 3-DoF manipulation rod that promotes better visualization and reduced risk of uterine damage.
  • Testing has shown impressive mechanical accuracy and load capacity, with successful trials in lab settings, ex-vivo, cadaver, and clinical scenarios.
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Oocyte vitrification technology is widely used for assisted reproduction and fertility preservation, which requires precise washing sequences and timings of cryoprotectant agents (CPAs) treatment to relieve the osmotic shock to cells. The gold standard Cryotop method is extensively used in oocyte vitrification and is currently the most commonly used method in reproductive centers. However, the Cryotop method requires precise and complex manual manipulation by an embryologist, whose proficiency directly determines the effect of vitrification.

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Embryo vitrification is a fundamental technology utilized in assisted reproduction and fertility preservation. Vitrification involves sequential loading and unloading of cryoprotectants (CPAs) with strict time control, and transferring the embryo in a minimum CPA droplet to the vitrification straw. However, manual operation still cannot effectively avoid embryo loss, and the existing automatic vitrification systems have insufficient system reliability, and operate differently from clinical vitrification protocol.

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The central nervous system has evolved to coordinate the regulation of both the behavior response to the external environment and homeostasis of energy expenditure. Recent studies have indicated the dorsomedial ventromedial hypothalamus (dmVMH) as an important hub that regulates both innate behavior and energy homeostasis for coping stress. However, how dmVMH neurons control neuronal firing pattern to regulate chronic stress-induced anxiety and energy expenditure remains poorly understood.

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  • This paper introduces an automatic method to reconstruct the surfaces of complex transparent objects using a dual-camera setup and laser scanning.
  • The approach identifies and categorizes 3D point candidates into first-reflection and non-first-reflection points, addressing the challenges posed by light transmission within transparent materials.
  • A four-layer refinement process is proposed to accurately extract first-reflection points, allowing for successful reconstruction of complex shapes of transparent objects compared to traditional methods.
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  • The COVID-19 pandemic has created significant challenges, particularly in the diagnosis process, which traditionally involves oropharyngeal swab sampling that puts medical staff at risk.
  • Soft robotic technology, specifically a novel design called the Tstone soft (TSS) hand, offers a solution that mimics human dexterity while improving safety and ease of use in confined spaces.
  • The TSS hand's innovative features, like a soft wrist and gripper, allow precise control and effective sampling, proving successful in experimental tests and presenting a viable option for tele-operated COVID-19 testing.
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Pollinators provide important ecosystem services for crop production and food security. With the development of agricultural economy and the increasing intensity of land-use, a large number of natural or semi-natural habitats have been converted to croplands. Landscape homogenization and intensive management lead to the decline of wild bee diversity and threaten the sustainable agricultural production.

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Three-dimensional (3D) reconstruction of dynamic objects has broad applications, including object recognition and robotic manipulation. However, achieving high-accuracy reconstruction and robustness to motion simultaneously is a challenging task. In this paper, we present a novel method for 3D reconstruction of dynamic objectS, whose main features are as follows.

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The scarcity of annotated surgical data in robot-assisted surgery (RAS) motivates prior works to borrow related domain knowledge to achieve promising segmentation results in surgical images by adaptation. For dense instrument tracking in a robotic surgical video, collecting one initial scene to specify target instruments (or parts of tools) is desirable and feasible during the preoperative preparation. In this paper, we study the challenging one-shot instrument segmentation for robotic surgical videos, in which only the first frame mask of each video is provided at test time, such that the pre-trained model (learned from easily accessible source) can adapt to the target instruments.

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Retinal vein cannulation (RVC) is a potential treatment for retinal vein occlusion (RVO). Manual surgery has limitations in RVC due to extremely small vessels and instruments involved, as well as the presence of physiological hand tremor. Robot-assisted retinal surgery may be a better approach to smooth and accurate instrument manipulation during this procedure.

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Magnetic resonance (MR) imaging (MRI) provides compelling features for the guidance of interventional procedures, including high-contrast soft tissue imaging, detailed visualization of physiological changes, and thermometry. Laser-based tumor ablation stands to benefit greatly from MRI guidance because 3D resection margins alongside thermal distributions can be evaluated in real time to protect critical structures while ensuring adequate resection margins. However, few studies have investigated the use of projection-based lasers like those for transoral laser microsurgery, potentially because dexterous laser steering is required at the ablation site, raising substantial challenges in the confined MRI bore and its strong magnetic field.

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Purpose: Automatic segmentation of surgical instruments in robot-assisted minimally invasive surgery plays a fundamental role in improving context awareness. In this work, we present an instance segmentation model based on refined Mask R-CNN for accurately segmenting the instruments as well as identifying their types.

Methods: We re-formulate the instrument segmentation task as an instance segmentation task.

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Robot-assisted vitreoretinal surgery can filter surgeons' hand tremors and provide safe, accurate tool manipulation. In this paper, we report the design, optimization, and evaluation of a novel tilt mechanism for a new Steady-Hand Eye Robot (SHER). The new tilt mechanism features a four-bar linkage design and has a compact structure.

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We consider the uncalibrated vision-based control problem of robotic manipulators in this work. Though lots of approaches have been proposed to solve this problem, they usually require calibration (offline or online) of the camera parameters in the implementation, and the control performance may be largely affected by parameter estimation errors. In this work, we present new fully uncalibrated visual servoing approaches for position control of the 2DOFs planar manipulator with a fixed camera.

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  • Jamming technologies show potential for variable stiffness mechanisms but face limitations in stiffening capacity and positioning.
  • A new variable stiffness mechanism is introduced that enhances stiffening capabilities, is biocompatible, and allows for rapid transitions between flexible and rigid states through a method called variable stiffness reconfiguration.
  • This mechanism enables customization of soft robotics applications, improving performance in complex manipulator postures and object grasping, and is supported by experimental evaluations and finite element modeling.
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This paper proposes a novel pretext task to address the self-supervised video representation learning problem. Specifically, given an unlabeled video clip, we compute a series of spatio-temporal statistical summaries, such as the spatial location and dominant direction of the largest motion, the spatial location and dominant color of the largest color diversity along the temporal axis, etc. Then a neural network is built and trained to yield the statistical summaries given the video frames as inputs.

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Aims: Chronic stress plays an important role in promoting the progression and migration of cancers. However, little is known of any direct impact on tumor progression related to the regulation of emotion-related circuitry. The aim of this study was to explore the neural-circuit mechanisms underlying stress-induced progression of cancers and the impact of emotion-related regulation of circuitry on tumor growth.

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Image lines projected from parallel 3D lines intersect at a common point called the vanishing point (VP). Manhattan world holds for the scenes with three orthogonal VPs. In Manhattan world, given several lines in a calibrated image, we aim to cluster them by three unknown-but-sought VPs.

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