Research on WSN reliable ranging and positioning algorithm for forest environment.

Wireless sensor network (WSN) location is a significant research area. In complex environments like forests, inaccurate signal intensity ranging is a major challenge. To address this issue, this paper presents a reliable WSN distance measurement-positioning algorithm for forest environments. The algorithm divides the positioning area into several sub-regions based on the discrete coefficient of the collected signal strength. Then, using the fitting method based on the signal intensity value of each sub-region, the algorithm derives the reference points of the logarithmic distance path loss model and path loss index. Finally, the algorithm locates target nodes using anchor nodes in different regions. Additionally, to enhance the positioning accuracy, weight values are assigned to the positioning result based on the discrete coefficient of the signal intensity in each sub-region. Experimental results demonstrate that the proposed WSN algorithm has high precision in forest environments.

Influence of spinal cord injury on core regions of motor function.

Functional electrical stimulation is an effective way to rebuild hindlimb motor function after spinal cord injury. However, no site map exists to serve as a reference for implanting stimulator electrodes. In this study, rat models of thoracic spinal nerve 9 contusion were established by a heavy-impact method and rat models of T6/8/9 spinal cord injury were established by a transection method. Intraspinal microstimulation was performed to record motion types, site coordinates, and threshold currents induced by stimulation. After transection (complete injury), the core region of hip flexion migrated from the T13 to T12 vertebral segment, and the core region of hip extension migrated from the L1 to T13 vertebral segment. Migration was affected by post-transection time, but not transection segment. Moreover, the longer the post-transection time, the longer the distance of migration. This study provides a reference for spinal electrode implantation after spinal cord injury. This study was approved by the Institutional Animal Care and Use Committee of Nantong University, China (approval No. 20190225-008) on February 26, 2019.

Three-dimensional Map of Lumbar Spinal Cord Motor Function for Intraspinal Microstimulation in Rats.

Intraspinal microstimulation is an effective method to rebuild motor function after spinal cord injury. However, in the implementation, available map of stimulation sites is lacking for reference. The location of electrode implantation can only be determined through multiple stimulation, causing secondary damage to the spinal cord. Therefore, in this paper, SD rats were chosen as the research subject, and the intraspinal microstimulation was used to perform three-dimensional scanning electrical stimulation on the lumbar spinal cord that controls the hindlimb motion. The site coordinates and corresponding threshold current that can induce motion of hip, knee and ankle joints were recorded. In order to reduce the individual variances and improve the universality and applicability of the map, the results of 6 groups were normalized, and three-dimensional map of spinal motor function were drawn in the same coordinate system. The overlap of the distribution area of the same motion in each group was defined as the core region. The threshold current of all sites were analyzed statistically to obtain the most appropriate range of current intensity required to induce hindlimb motion. Using appropriate current for intraspinal microstimulation in the core region can selectively induce desired hindlimb motion, greatly improving the accuracy and reliability of electrode implantation.

Portable, low cost smartphone-based potentiostat system for the salivary α-amylase detection in stress paradigm.

The aim of this study was to explore a novel, low-cost smartphone-based biosensor system and establish an efficient analysis method for the detection of potential stress biomarker, salivary α-amylase(sAA). This system consists of Smartphone with sAA-detection, Screen-printed electrodes(SPEs) and potentiostat module. The presented technique that using a small perturbation to obtain a linearized response could affect the composition of the sample as to cyclic voltammetry which repeatedly reduces and oxidizes the sample. For application, 6 healthy graduate students took a 5 minutes Trier Social Stress Test(TSST). Results show that this method could detect sAA activities conveniently and accurately. Calibration curve of sAA whose quantitative range is from 50 and 1200 U mL-1 with a limit of detection(LOD) of 1.6 U mL-1, is Y=-52.324X+295.63, R^2=0.9933. After psychological stress, sAA secretion was significant verified. It is concluded that this smartphone-based sAA detection system is reliable for determination of Salivary α-amylase and useful in the assessment of Psychological stress.

Comparative Study of Intraspinal Microstimulation and Epidural Spinal Cord Stimulation.

Intraspinal microstimulation and epidural spinal cord stimulation can be considered as the technique to restore function following spinal cord injury through further research. In this paper, the automatic brain stereotaxic instrument was used to electrically stimulate the lumbosacral spinal cord (T12-L2 spinal segments) in rats. The motor function regions under intraspinal microstimulation and epidural spinal cord stimulation were measured. Threshold currents and coordinate sites of related motions were recorded. Comparative analysis revealed that the threshold current required for epidural stimulation to induce hindlimb motion was greater. Although the distribution of motor function regions measured by these two methods differed in the type of motion, the segment distribution of each motion were roughly the same. Therefore, if conditions permit, epidural stimulation can be used instead of intraspinal microstimulation to reduce secondary damage to the spinal cord. This provides a reference for locating stimulation sites for epidural spinal cord stimulation.

[Selective control of hindlimb movements based on intraspinal functional electronic stimulation].

Functional electronic stimulation (FES) may provide a means to restore motor function in patients with spinal cord injuries. The goal of this study is to determine the regions in the spinal cord controlling different hindlimb movements in the rats. Normalization was used for the regions dominating the corresponding movements. It has been verified that FES can be used in motor function recovery of the hindlimb. The spinal cord was stimulated by FES with a three-dimensional scan mode in experiments. The results show that stimulation through the electrodes implanted in the ventral locations of the lumbosacral enlargement can produce coordinated single- and multi-joint hindlimb movements. A variety of different hindlimb movements can be induced with the appropriate stimulation sites, and movement vectors of the hindlimb cover the full range of movement directions in the sagittal plane of the hindlimb. This article drew a map about spinal cord motor function of the rat. The regions in the spinal cord which control corresponding movements are normalized. The data in the study provide guidance about the location of electrode tips in the follow-up experiments.