A neuromusculoskeletal modelling approach to bilateral hip mechanics due to unexpected lateral perturbations during overground walking.

BACKGROUND: Current studies on how external perturbations impact gait dynamics have primarily focused on the changes in the body's center of mass (CoM) during treadmill walking. The biomechanical responses, in particular to the multi-planar hip joint coordination, following perturbations in overground walking conditions are not completely known. METHODS: In this study, a customized gait-perturbing device was designed to impose controlled lateral forces onto the subject's pelvis during overground walking. The biomechanical responses of bilateral hips were simulated by subject-specific neuromusculoskeletal models (NMS) driven by in-vivo motion data, which were further evaluated by statistical parameter mapping (SPM) and muscle coactivation index (CI) analysis. The validity of the subject-specific NMS was confirmed through comparison with measured surface electromyographic signals. RESULTS: Following perturbations, the sagittal-plane hip motions were reduced for the leading leg by 18.39° and for the trailing leg by 8.23°, while motions in the frontal and transverse plane were increased, with increased hip abduction for the leading leg by 10.71° and external rotation by 9.06°, respectively. For the hip kinetics, both the bilateral hip joints showed increased abductor moments during midstance (20%-30% gait cycle) and decreased values during terminal stance (38%-48%). Muscle CI in both sagittal and frontal planes was significantly decreased for perturbed walking (p < 0.05), except for the leading leg in the sagittal plane. CONCLUSION: The distinctive phase-dependent biomechanical response of the hip demonstrated its coordinated control strategy for balance recovery due to gait perturbations. And the changes in muscle CI suggested a potential mechanism for rapid and precise control of foot placement through modulation of joint stiffness properties. These findings obtained during actual overground perturbation conditions could have implications for the improved design of wearable robotic devices for balance assistance.

Functional effects of arthroscopic modified Broström procedure on lateral ankle instability: A pilot study.

BACKGROUND: This study aims to assess the mechanical and functional effects of the arthroscopic modified Broström procedure (AMBP) on patients with lateral ankle instability. METHODS: Eight patients with unilateral ankle instability treated with AMBP and eight healthy subjects were recruited. Healthy subjects, preoperative and one-year postoperative patients were assessed using outcome scales and the Star Excursion Balance Test (SEBT) for dynamic postural control. One-dimensional statistical parametric mapping was performed to compare ankle angle and muscle activation curve during stair descent. RESULTS: The patients with lateral ankle instability showed good clinical outcomes and increased posterior lateral reach during the SEBT after the AMBP (p = 0.046). The medial gastrocnemius activation after initial contact was reduced (p = 0.049), and the peroneal longus activation after initial contact was promoted (p = 0.014). CONCLUSION: The AMBP has functional effects of promoting dynamic postural control and peroneal longus activation within one year of follow-up, which can benefit patients with functional ankle instability. However, the medial gastrocnemius activation was unexpectedly reduced post operation.

Robust shallow water reverberation reduction methods based on low-rank and sparsity decomposition.

Using the characteristics of low rank for reverberation and sparsity for the target echo in multi-ping detection, the low-rank and sparsity decomposition method can effectively reduce reverberation. However, in the case of highly sparse reverberation or a stationary target, the distinctions in the characteristics between the reverberation and target echo become ambiguous. As a result, the reverberation reduction performance is degraded. To guarantee a meaningful decomposition based on the random orthogonal model and random sparsity model, the identifiability condition (IC) for the decomposition was derived from the perspective of the low-rank matrix and sparse matrix, respectively. According to the IC, sparsity compensation for the low-rank matrix was proposed to address the false alarm probability inflation (FAPI) induced by highly sparse reverberation. In addition, increasing the dimension of the sparse matrix was also proposed to manage the detection probability shrinkage caused by a stationary target. The robust reverberation reduction performance was validated via simulations and field experiments. It is demonstrated that FAPI can be eliminated by increasing the sparse coefficient of the low-rank matrix to 0.30 and a stationary target could be detected with a large ping number, i.e., a high dimension, of the sparse matrix.

Exploring a New Adaptive Routing Based on the Dijkstra Algorithm in Optical Networks-on-Chip.

The photoelectric hybrid network has been proposed to achieve the ultrahigh bandwidth, lower delay, and less power consumption for chip multiprocessor (CMP) systems. However, a large number of optical elements used in optical networks-on-chip (ONoCs) generate high transmission loss which will influence network performance severely and increase power consumption. In this paper, the Dijkstra algorithm is adopted to realize adaptive routing with minimum transmission loss of link and reduce the output power of the link transmitter in mesh-based ONoCs. The numerical simulation results demonstrate that the transmission loss of a link in optimized power control based on the Dijkstra algorithm could be maximally reduced compared with traditional power control based on the dimensional routing algorithm. Additionally, it has a greater advantage in saving the average output power of optical transmitter compared to the adaptive power control in previous studies, while the network size expands. With the aid of simulation software OPNET, the network performance simulations in an optimized network revealed that the end-to-end (ETE) latency and throughput are not vastly reduced in regard to a traditional network. Hence, the optimized power control proposed in this paper can greatly reduce the power consumption of s network without having a big impact on network performance.

A Novel Algorithm for Routing Paths Selection in Mesh-Based Optical Networks-on-Chips.

Optical networks-on-chips (ONoCs) is an effective and extensible on-chip communication technology, which has the characteristics of high bandwidth, low consumption, and low delay. In the design process of ONoCs, power loss is an important factor for limiting the scalability of ONoCs. Additionally, the optical signal-to-noise ratio (OSNR) is an index to measure the quality of ONoCs. Nowadays, the routing algorithm commonly used in ONoCs is the dimension-order routing algorithm, but the routing paths selected by the algorithm have high power loss and crosstalk noise. In this paper, we propose a 5×5 all-pass optical router model for two-dimensional (2-D) mesh-based ONoCs. Based on the general optical router model and the calculation models of power loss and crosstalk noise, a novel algorithm is proposed in ordder to select the routing paths with the minimum power loss. At the same time, it can ensure that the routing paths have the approximately optimal OSNR. Finally, we employ the Cygnus optical router to verify the proposed routing algorithm. The results show that the algorithm can effectively reduce the power loss and improve the OSNR in the case of network sizes of 5×5 and 6×6. With the increase of the optical network scale, the algorithm can perform better in reducing the power loss and raising the OSNR.

Reverberation reduction based on multi-ping association in a moving target scenario.

Conventional reverberation reduction methods are conducted with single-ping data and may fail in a low signal-to-reverberation ratio (SRR) environment. To improve the performance of reverberation reduction, multi-ping data are fully considered in this paper. The reverberation can be treated as a combination of the steady component of reverberation and reverberation fluctuations, and then an alternating direction multiplier method is proposed to reduce the steady component of the reverberation. By exploiting the evolution of the target location along multiple pings, the reverberation fluctuation is reduced by the probabilistic data association method. The proposed method was verified by the field data, and the results show that compared with the accelerated proximal gradient method, the sparse coefficient is improved by a factor of 1.23, and the signal excess is improved by an average value of 2.0 dB. In addition, the performance of the proposed method is found to be closely related to the signal-to-reverberation-fluctuation ratio rather than only the SRR.

[Effects of Shiquanyuzhentang on immunologic function of H22 tumor-bearing mouse].

OBJECTIVE: To investigate the effects of Shiquanyuzhentang (Traditional Chinese Medicine) on the immunologic function of tu-mor-bearing mice and its mechanism of antitumor. METHODS: Thirty SPF grade male Kunming mice transplanted with H22 hepatocellular carci-noma were divided into three groups randomly:model group,positive control group and Shiquanyuzhentang group(n=10). Another 10 mice were selected as normal control group. Normal control group and model group received normal saline and distilled water supplementation by 10 mL/kg everyday. Positive control group and Shiquanyuzhentang group received Shengyi(80 mg/ml)and Shiquanyuzhentang decoction at the doses of 8 g/kg and 18 g/kg respectively everyday. After 14 days of continuous administration, the mice were killed and the thymus, spleen index, tumor inhibition rate,peripheral blood leukocytes,lymphocyte content,cell percentage of T cell subsets CD3, CD4, CD8,interleukin 2 (IL-2)in serum,tumor necrosis factor-α(TNF-α),interferon ß(IFN-ß) content,lymphocyte proliferation ability and NK cell were measured. RESULTS: Compared with normal control group, the weight of mice and thymus and spleen index of the Shiquanyuzhentang group were increased significantly(P<0.05);leukocyte and lymphocyte CD3、CD4、CD8 and TNF-α were increased greatly(P<0. 05),IL-2 and IFN-ß were de-creased significantly(P<0.05). Compared with model group,thymus and spleen index of Shiquanyuzhentang group were increased significant-ly(P<0.05);leukocyte and lymphocyte CD3、CD4、IL-2、IFN-ß and TNF-α of Shiquanyuzhentang group were increased significantly(P<0. 05),CD8 content was decreased significantly(P<0.05);NK cell and lymphocyte proliferation were increased significantly(P<0.05). CONCLUSIONS: Shiquanyuzhentang can promote the growth of immune organs in mice bearing H22, enhance immune function and is beneficial to the recovery of tumor body.