Highly divergent morphology but a close molecular phylogenetic relationship between two little-known ciliate genera Actinobolina and Papillorhabdos (Protozoa: Ciliophora: Litostomatea) with description of two new species.

Free-living litostomatean ciliates, prominent microeukaryote predators commonly encountered in freshwater and marine habitats, play vital roles in maintaining energy flow and nutrient cycles. Nevertheless, understanding their biodiversity and phylogenetic relationships remains challenging due to insufficient morphological information and molecular data. As a new contribution to this group, three haptorian ciliates, including two new species (Actinobolina bivacuolata sp. nov. and Papillorhabdos foissneri sp. nov.) and the insufficiently described type species, Actinobolina radians, were isolated from wetlands around Lake Weishan, China and investigated by a combination of living morphology, stained preparations, and 18S rRNA gene sequence data. An illustrated key of the valid species within the two genera is provided. In addition, we reveal the phylogenetic positions of these two genera for the first time. Although they differ in all key morphologic characters such as general appearance (ellipsoidal with numerous tentacles vs. cylindrical), extrusomes (stored in tentacles vs. anchored to pellicle), circumoral kinety (present vs. absent), composition of somatic kineties (kinetosome clusters vs. monokinetids), and number of dorsal brush rows (1 vs. 4), they both cluster in a fully supported clade in the phylogenetic tree, which indicates that the biodiversity and additional molecular markers of this group need further exploration.

New contribution to the peritrichous genus Ophrydium (Protista, Ciliophora) with notes on the morphology, taxonomy, and phylogeny of a well-known species Ophrydium crassicaule Penard, 1922.

The peritrichous genus Ophrydium is relatively distinctive since its colonies have a gelatinous lorica. In the present work, one morphologically well-described species, Ophrydium crassicaule, was collected from a freshwater habitat in China. Both morphological characters and sequence data for SSU rDNA, ITS1-5.8S-ITS2 region and LSU rDNA were obtained. Morphologically, O. crassicaule is characterized by its elongated vase-shaped zooid, single-layered peristomial lip, dichotomously branched stalk, colony with gelatinous lorica, and infundibular polykinety 3 (P3) containing one short inner row and two long outer rows. Phylogenetic analyses revealed that the genus Ophrydium is monophyletic and nests within the family Vorticellidae. In addition, we briefly revise the nominal congeners for aiding the species identification in future studies.

Recognition Method of Massage Techniques Based on Attention Mechanism and Convolutional Long Short-Term Memory Neural Network.

Identifying the massage techniques of the masseuse is a prerequisite for guiding robotic massage. It is difficult to recognize multiple consecutive massage maps with a time series for current human action recognition algorithms. To solve the problem, a method combining a convolutional neural network, long-term neural network, and attention mechanism is proposed to identify the massage techniques in this paper. First, the pressure distribution massage map is collected by a massage glove, and the data are enhanced by the conditional variational auto-encoder. Then, the features of the massage map group in the spatial domain and timing domain are extracted through the convolutional neural network and the long- and short-term memory neural network, respectively. The attention mechanism is introduced into the neural network, giving each massage map a different weight value to enhance the network extraction of data features. Finally, the massage haptic dataset is collected by a massage data acquisition system. The experimental results show that a classification accuracy of 100% is achieved. The results demonstrate that the proposed method could identify sequential massage maps, improve the network overfitting phenomenon, and enhance the network generalization ability effectively.

Sea-Surface Target Visual Tracking with a Multi-Camera Cooperation Approach.

Cameras are widely used in the detection and tracking of moving targets. Compared to target visual tracking using a single camera, cooperative tracking based on multiple cameras has advantages including wider visual field, higher tracking reliability, higher precision of target positioning and higher possibility of multiple-target visual tracking. With vast ocean and sea surfaces, it is a challenge using multiple cameras to work together to achieve specific target tracking and detection, and it will have a wide range of application prospects. According to the characteristics of sea-surface moving targets and visual images, this study proposed and designed a sea-surface moving-target visual detection and tracking system with a multi-camera cooperation approach. In the system, the technologies of moving target detection, tracking, and matching are studied, and the strategy to coordinate multi-camera cooperation is proposed. The comprehensive experiments of cooperative sea-surface moving-target visual tracking show that the method used in this study has improved performance compared with contrapositive methods, and the proposed system can meet the needs of multi-camera cooperative visual tracking of moving targets on the sea surface.

[Analysis on muscle force and injured femoral reduction force based on new muscle tendon model].

Robot-assisted fracture reduction usually involves fixing the proximal end of the fracture and driving the distal end of the fracture to the proximal end in a planned reduction path. In order to improve the accuracy and safety of reduction surgery, it is necessary to know the changing rule of muscle force and reduction force during reduction. Fracture reduction force was analyzed based on the muscle force of femoral. In this paper, a femoral skeletal muscle model named as PA-MTM was presented based on the four elements of skeletal muscle model. With this, pinnate angle of the skeletal muscle was considered, which had an effect on muscle force properties. Here, the muscle force of skeletal muscles in different muscle models was compared and analyzed. The muscle force and the change of the reduction force under different reduction paths were compared and simulated. The results showed that the greater the pinnate angle was, the greater the influence of muscle strength was. The biceps femoris short head played a major role in the femoral fracture reduction; the force in the z direction contributed the majority to the resulting force with maximums of 472.18 N and 497.28 N for z and resultant, respectively, and the rationality of the new musculoskeletal model was verified.

[Development of on-line lateral stiffness measurement system for anterior cruciate ligament and its influence on anterior cruciate ligament reconstruction].

The anterior cruciate ligament (ACL) reconstruction mostly relies on the experience of surgeons. To improve the effectiveness and adaptability of the tension after ACL reconstruction in knee joint rehabilitation, this paper establishes a lateral force measurement model with relaxation characteristics and designs an on-line stiffness measurement system of ACL. In this paper, we selected 20 sheep knee joints as experimental material for the knee joint stability test before the ACL reconstruction operation, which were divided into two groups for a comparative test of single-bundle ACL reconstruction through the anterolateral approach. The first group of surgeons carried out intraoperative detection with routine procedures. The second group used ACL on-line stiffness measurement system for intraoperative detection. After that, the above two groups were tested for postoperative stability. The study results show that the tension accuracy is (- 2.3 ± 0.04)%, and the displacement error is (1.5 ± 1.8)%. The forward stability, internal rotation stability, and external rotation stability of the two groups were better than those before operation ( P < 0.05). But the data of the group using the system were closer to the preoperative knee joint measurement index, and there was no significant difference between them ( P > 0.05). The system established in this paper is expected to help clinicians judge the ACL reconstruction tension in the operation process and effectively improve the surgical effect.

Biomechanical characteristics of arteries during pelvic fracture reduction and dynamic simulation analysis.

During robot-assisted reduction of pelvic fracture, blood vessels are susceptible to tensile and shear forces, making them prone to injury. Considering the impact of pelvic reduction on the risk of arterial injury, the biomechanical characteristics of arteries during the pelvic fracture reduction process are studied, and a refined coupled composite model of the damaged pelvic structure is established. Dynamic simulations of pelvic fracture reduction are conducted based on the planned reduction path. The simulation results show that during the reduction process, when the affected side is rotated, the stress and strain of the artery are maximum, particularly at the locations of the iliac common artery, internal iliac artery, and the superior gluteal artery arch endure significant stress and strain. After reduction, the maximum stress is observed in the right superior gluteal artery, and the maximum strain occurs at the intersection of the right iliac common artery. The stretch ratio of both the left and right iliac common arteries is considerable. Therefore, it can be concluded that the superior gluteal artery and the internal iliac artery are prone to injury, particularly the segment from the origin of the superior gluteal artery to its passage around the greater sciatic notch. After reduction, substantial traction on the iliac common artery, which makes it more susceptible to deformation, carries a risk of arterial rupture and aneurysm formation. This study provides a reference for planning the safe reduction path of pelvic fracture surgery and improving safety.

Study on circumpelvic muscle deformation and dynamic simulation of pelvic fracture reduction.

For the pelvic fracture reduction, generally the fragment of the unaffected side is fixed and the affected side is moved to its correct anatomical position and orientation. During the pelvic fracture reduction, circumpelvic muscles deformation is closely related to the surgical accuracy. In this article, the biomechanical properties of musculoskeletal tissue during pelvic fracture reduction are studied. Five-parameter hyperelastic model named Mooney-Rivlin is adopted to analyze muscle's stress-strain relationship. The finite element model of the injured pelvic musculoskeletal tissue is established, and the deformation of circumpelvic main muscles is simulated. Then, the dynamic simulation of pelvic fracture reduction is performed according to the planned spatial reduction path. The results show that when the muscles are stretched the same stretch length, the strain of the gluteus medius is the largest. It is most prone to deformation under and the muscle injury is most easily to occur. During the pelvic fracture reduction, the strain of gluteus maximus is the largest, and it is most prone to deformation and injury. The traction length is the largest, and the traction force mainly comes from the gluteus maximus. This study provides reference for the robot assisted pelvic fracture reduction.

Adaptive variable impedance position/force tracking control of fracture reduction robot.

BACKGROUND: The operation object of robot-assisted fracture reduction surgery is the musculoskeletal tissue with rigid-compliance coupling characteristics. It is necessary to improve the interactive compliance and safety between the reduction robot and the musculoskeletal tissue. METHOD: An adaptive variable impedance position/force tracking control strategy based on friction compensation is proposed. The stiffness of the reduction robot can be adaptively adjusted according to the contact force between the end-effector and the environment. The Stribeck friction force model of the branch chain electric cylinder is derived to improve the motion control performance. RESULTS: The fracture reduction experiment is completed. The experimental results show that the adaptive variable impedance position/force control strategy can realize position and force tracking in fracture reduction. CONCLUSION: A safety control strategy is proposed and applied to robot-assisted fracture reduction surgery, which improves the coordination and compliance of the human-robot interaction between the reduction robot and the patient.

Design and simulation verification of clamping instrument with active variable stiffness for pelvic fracture reduction.

BACKGROUND: During the robot-assisted pelvic fracture reduction process, the clamping instrument are subjected to the large reduction force from the robot, resulting in inevitable great stress concentration and deformation of the bone pins, affecting the fracture reduction accuracy. METHOD: A compact and easily-to-adjust clamping instrument with active variable stiffness is designed. The relationship between the component's elongation and the clamping instrument's deformation and stiffness is derived and calculated. Furthermore, the finite element model of the fixed and the variable stiffness clamping instruments connecting with the injured pelvic musculoskeletal tissue is developed, respectively. RESULTS: Applying the same reduction force, the deformation of the clamping instrument with variable stiffness is reduced, especially in the elongated state. Moreover, the new clamping instrument meets the strength requirements and makes a better stress distribution. CONCLUSION: The clamping instrument can achieve stiffness adjustment during the reduction process and will be used for improving the surgery accuracy.

Design and Joint Position Control of Bionic Jumping Leg Driven by Pneumatic Artificial Muscles.

Using the skeletal structure and muscle distribution of the hind limbs of a jumping kangaroo as inspiration, a bionic jumping leg was designed with pneumatic artificial muscles (PAMs) as actuators. Referring to the position of biarticular muscles in kangaroos, we constructed a bionic joint using biarticular and monoarticular muscle arrangements. At the same time, the problem of the joint rotation angle limitations caused by PAM shrinkage was solved, and the range of motion of the bionic joint was improved. Based on the output force model of the PAM, we established a dynamic model of the bionic leg using the Lagrange method. In view of the coupling problem caused by the arrangement of the biarticular muscle, an extended state observer was used for decoupling. The system was decoupled into two single-input and single-output systems, and angle tracking control was carried out using active disturbance rejection control (ADRC). The simulation and experimental results showed that the ADRC algorithm had a better decoupling effect and shorter adjustment time than PID control. The jumping experiments showed that the bionic leg could jump with a horizontal displacement of 320 mm and a vertical displacement of 150 mm.

Constraint of musculoskeletal tissue and path planning of robot-assisted fracture reduction with collision avoidance.

BACKGROUND: For the robot-assisted fracture reduction, due to the complex fracture musculoskeletal environment, it is necessary to consider the influence of soft tissue traction on preoperative reduction path planning. METHOD: An improved 3D A* algorithm is adopted to plan the fracture reduction path. The distal fragment point clouds are updated to avoid the collision, and the end point coordinates of the muscles are updated to calculate muscular lengths during the path search. RESULTS: 3D reduction path of long-bone fracture is planned, effectively avoiding the fracture fragments collision and ensuring the length of the corresponding muscle is always less than the allowable maximum muscle length after elongation. CONCLUSION: The proposed method can effectively avoid the collision between the distal fragment and the proximal fragment during the fracture reduction, can avoid secondary injury of the muscles around the femoral bone caused by over-distraction, and effectively improve the safety of robot reduction operation.