Sparse reservoir computing with vertically coupled vortex spin-torque oscillators for time series prediction.

Spin torque nano-oscillators possessing fast nonlinear dynamics and short-term memory functions are potentially able to achieve energy-efficient neuromorphic computing. In this study, we introduce an activation-state controllable spin neuron unit composed of vertically coupled vortex spin torque oscillators and aV-Isource circuit is proposed and used to build an energy-efficient sparse reservoir computing (RC) system to solve nonlinear dynamic system prediction task. Based on micromagnetic and electronic circuit simulation, the Mackey-Glass chaotic time series and the real motor vibration signal series can be predicted by the RC system with merely 20 and 100 spin neuron units, respectively. Further study shows that the proposed sparse reservoir system could reduce energy consumption without significantly compromising performance, and a minimal response from inactivated neurons is crucial for maintaining the system's performance. The accuracy and signal processing speed show the potential of the proposed sparse RC system for high-performance and low-energy neuromorphic computing.

Repair of Finger Pulp Defect and Sensory Reconstruction Using Reverse Homodigital Artery Island Flap With Palmar Cutaneous Branches of the Proper Digital Nerve.

OBJECTIVE: To illustrate the clinical outcomes of the reverse digital proper artery island flap with anastomosing the palmar cutaneous branches of the proper digital nerve for the reconstruction of finger pulp defects. METHODS: From December 2007 to December 2017, a total of 20 patients with finger pulp defects were treated with reverse digital proper artery island flap for innervated construction. Functional outcomes, aesthetic appearance, and complications were evaluated. Functional outcomes were assessed according to range of motion, sensory grade (S0-S4), static 2-point discrimination, Semmes-Weinstein monofilament test, and Cold Intolerance Severity Score. Aesthetic appearance was evaluated according to the Michigan Hand Outcomes Questionnaire. RESULTS: All flaps survived completely without any complications, and all patients were followed up for at least 12 months. The average static 2-point discrimination, Semmes-Weinstein monofilament, and Cold Intolerance Severity Score results of the injured fingers were 6.35 mm (range, 5-8 mm), 3.64 (range, 2.83-4.17), and 19 (range, 8-24), respectively. All patients achieved recovery in sensation from S3+ to S4. The active ranges of motion of the metacarpophalangeal, proximal interphalangeal, and distal interphalangeal joints of the affected fingers were satisfactory. Based on the Michigan Hand Outcomes Questionnaire, 11 patients were strongly satisfied, and 9 were satisfied with the appearance of the injured finger. CONCLUSIONS: The reverse digital proper artery island flap with anastomosing the palmar cutaneous branches of the proper digital nerve is an effective and reliable alternative for the reconstruction of finger pulp defect. In the recovery of sensation, this flap leads to satisfactory effects.

Reverse digital artery island flap with versus without sensory nerve coaptation for finger pulp reconstruction.

PURPOSE: Whether an innervated reverse digital artery island flap is superior to a non-innervated reverse digital artery island flap still remains controversial. We aimed to compare the clinical outcomes of the two flaps in repairing finger pulp soft tissue defects. METHODS: Medical records of patients who underwent finger pulp reconstruction between January 2007 and December 2017 were evaluated retrospectively. A total of 45 patients were included. Twenty underwent sensory nerve reconstruction with cutaneous branches of the proper digital nerve, and 25 underwent the surgery without sensory nerve reconstruction. Surgical results, complications and sensory function were collected for analysis. Sensory function was assessed by static two-point discrimination and the modified sensory evaluation standard of British Medical Research Council. RESULTS: The average operation time of innervated flaps was 23 min longer than non-innervated flaps. All 45 flaps survived completely. There was no significant difference in complications between groups. The average follow-up was 22 months. At the final follow-up, five non-innervated flaps had no recovery of static two-point discrimination. The average static two-point discrimination of the remaining 20 non-innervated flaps was larger than that of innervated flaps. Innervated flaps consistently achieved higher sensory function grades according to the modified sensory evaluation standard of British Medical Research Council. CONCLUSION: An innervated reverse digital artery island flap can achieve better sensory function recovery in a shorter time. This procedure did not increase the incidence of complications, although it extended the operation time. It has proven to be a good technique for finger pulp reconstruction.