A sEMG-driven Musculoskeletal Model to Control Exoskeleton Robot Used in Lower Extremity Rehabilitation

A control system framework of lower extremity rehabilitation exoskeleton robot is presented. It is based on the Neuro-Musculo-Skeletal biological model. Its core composition module, the motion intent parser part, mainly comprises of three distinct parts. The first part is signal acquisition of surface electromyography (sEMG) that is the summation of motor unit action potential (MUAP) starting from central nervous system (CNS).sEMG can be used to decode action intent of operator to make the patient actively participate in specific training .As another composition part, a muscle dynamics model that is comprised of activation and contraction dynamic model is developed. It is mainly used to calculate muscle force. The last part is the skeletal dynamic model that is simplified as a linked segment mechanics. Combined with muscle dynamic model, the joint torque exerted by internal muscles can be exported, which can be used to do a exoskeleton controller design. The developed control framework can make exoskeleton offer assistance to operators during rehabilitation by guiding motions on correct training rehabilitation trajectories, or give force support to be able to perform certain motions. Though the presentation is orientated towards the lower extremity exoskeleton, it is generic and can be applied to almost any part of the human body

Goal-directed fluid optimization based on stroke volume variation and cardiac index during one-lung ventilation in patients undergoing thoracoscopy lobectomy operations: a pilot study

OBJECTIVES: This pilot study was designed to utilize stroke volume variation and cardiac index to ensure fluid optimization during one-lung ventilation in patients undergoing thoracoscopic lobectomies. METHODS: Eighty patients undergoing thoracoscopic lobectomy were randomized into either a goal-directed therapy group or a control group. In the goal-directed therapy group, the stroke volume variation was controlled at 10%±1%, and the cardiac index was controlled at a minimum of 2.5 L.min-1.m-2. In the control group, the MAP was maintained at between 65 mm Hg and 90 mm Hg, heart rate was maintained at between 60 BPM and 100 BPM, and urinary output was greater than 0.5 mL/kg-1/h-1. The hemodynamic variables, arterial blood gas analyses, total administered fluid volume and side effects were recorded. RESULTS: The PaO2/FiO2-ratio before the end of one-lung ventilation in the goal-directed therapy group was significantly higher than that of the control group, but there were no differences between the goal-directed therapy group and the control group for the PaO2/FiO2-ratio or other arterial blood gas analysis indices prior to anesthesia. The extubation time was significantly earlier in the goal-directed therapy group, but there was no difference in the length of hospital stay. Patients in the control group had greater urine volumes, and they were given greater colloid and overall fluid volumes. Nausea and vomiting were significantly reduced in the goal-directed therapy group. CONCLUSION: The results of this study demonstrated that an optimization protocol, based on stroke volume variation and cardiac index obtained with a FloTrac/Vigileo device, increased the PaO2/FiO2-ratio and reduced the overall fluid volume, intubation time and postoperative complications (nausea and vomiting) in thoracic surgery patients requiring one-lung ventilation

Enhanced inhibitory synaptic transmission in the spinal dorsal horn mediates antinociceptive effects of TC-2559

<p>Abstract</p> <p>Background</p> <p>TC-2559 is a selective α4β2 subtype of nicotinic acetylcholine receptor (nAChR) partial agonist and α4β2 nAChR activation has been related to antinociception. The aim of this study is to investigate the analgesic effect of TC-2559 and its underlying spinal mechanisms.</p> <p>Results</p> <p>1) <it>In vivo </it>bioavailability study: TC-2559 (3 mg/kg) had high absorption rate in rats with maximal total brain concentration reached over 4.6 μM within first 15 min after administration and eliminated rapidly with brain half life of about 20 min after injection. 2) <it>In vivo </it>behavioral experiments: TC-2559 exerts dose dependent antinociceptive effects in both formalin test in mice and chronic constriction injury (CCI) model in rats by activation of α4β2 nAChRs; 3) Whole-cell patch-clamp studies in the superficial dorsal horn neurons of the spinal cord slices: perfusion of TC-2559 (2 μM) significantly increased the frequency, but not amplitude of spontaneous inhibitory postsynaptic currents (sIPSCs). The enhancement of sIPSCs was blocked by pre-application of DHβE (2 μM), a selective α4β2 nicotinic receptor antagonist. Neither the frequency nor the amplitude of spontaneous excitatory postsynaptic currents (sEPSCs) of spinal dorsal horn neurons were affected by TC-2559.</p> <p>Conclusions</p> <p>Enhancement of inhibitory synaptic transmission in the spinal dorsal horn via activation of α4β2 nAChRs may be one of the mechanisms of the antinociceptive effects of TC-2559 on pathological pain models. It provides further evidence to support the notion that selective α4β2 subtype nAChR agonist may be developed as new analgesic drug for the treatment of neuropathic pain.</p

Activity of the Mianzishan-Qingshuiying fault in the southeast margin of the Yinchuan basin

Studying the tectonic activity characteristics of the Yinchuan basin is of great significance for understanding the interaction among the three major blocks of Qinghai Tibet, Ordos and Alxa. The terrain elevation difference in the Mianzishan-Zhutouling area on the southeastern margin of the Yinchuan basin is significant, and the linear trace on satellite image is obvious, indicating the development of an unknown active fault. This article conducted field geological surveys, trench excavation and stratigraphic dating along the Mianzishan-Qingshuiying line. The results showed that the linear trace along the Mianzishan-Qingshuiying line had been dominated by fault, which was developed on the southeastern margin of the Yinchuan basin with a total length of 50 km. It is divided into two segments, the Mianzishan fault and the Qingshuiying fault. The Mianzishan fault is mainly characterized by high angle normal faults, the scratches on the fault surface show a sinistral strike slip motion, heading northeast, several gullies across the fault layer display left-handed twisting characteristics. The Qingshuiying fault, on the other hand，exhibits a reverse fault trending NEE, developing steep slope landforms. The fault has displaced sedimentary strata deposited at (23.65 ± 1.17) ka BP and (33.16 ± 1.82) ka BP, indicating its latest activity was postdated by Late Pleistocene. The discovery of this fault indicates that the boundary of the northwestern Ordos block is a complex zone associated with a wide structural deformation zone. This zone is not strictly controlled by the boundary faults of Yinchuan basin, but expanded to interior of the Ordos block, which may be related to the continuous northeast pushing and expansion of the Qinghai Tibet Plateau

Measurement-device-independent quantum key distribution over untrustful metropolitan network

Quantum cryptography holds the promise to establish an information-theoretically secure global network. All field tests of metropolitan-scale quantum networks to date are based on trusted relays. The security critically relies on the accountability of the trusted relays, which will break down if the relay is dishonest or compromised. Here, we construct a measurement-device-independent quantum key distribution (MDIQKD) network in a star topology over a 200 square kilometers metropolitan area, which is secure against untrustful relays and against all detection attacks. In the field test, our system continuously runs through one week with a secure key rate ten times larger than previous result. Our results demonstrate that the MDIQKD network, combining the best of both worlds --- security and practicality, constitutes an appealing solution to secure metropolitan communications.Comment: 17 pages, 4 figure

Low-frequency micro/nano-vibration generator using a piezoelectric actuator

Low-frequency vibration must be detected because of its harmful effects on micro/nano measuring machines. Thus, the authors developed a low-cost and high-precision detector for low-frequency micro-vibration. A high-precision vibration generator is required to calibrate the vibration detector because of the high cost and complex structure of existing vibration generators. A new vibration generator that can produce low-cost and high-precision lowfrequency vibration was also developed. A piezoelectric actuator is used as a vibration exciter, which is driven by a high-precision signal generator and a high-voltage amplifier. A beryllium bronze-based leaf spring was used as an elastic component, which is optimally designed and verified by the ANSYS software. The proper size and natural frequency of the leaf spring were obtained. The leaf spring was fixed horizontally on a four-point cylinder-shaped pedestal and driven by the actuator vertically. The worktable on the top surface of the leaf spring only had an up-and-down direction. A high-precision eddy current sensor was used to test the performance of the developed vibration generator. Experimental results show that the vibration generator can produce simple harmonic vibrations with a frequency and amplitude ranges of 10–50 Hz and 0.90–19.87 μm, respectively, and the repeatability of the open-looped vibration amplitude is less than 90 nm (K=2). The developed vibration generator can be used when a micro/nano-vibration detector is calibrated