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Abstract: The synaptic weight modification depends not only on interval of the pre‐/postspike pairs according to spike‐timing dependent plasticity (classical pair‐STDP), but also on the timing of the preceding spike (triplet‐STDP). Triplet‐STDP reflects the unavoidable interaction of spike pairs in natural spike trains through the short‐term suppression effect of preceding spikes. Second‐order memristors with one state variable possessing short‐term dynamics work in a way similar to the biological system. In this work, the suppression triplet‐STDP learning rule is faithfully demonstrated by experiments and simulations using second‐order memristors. Furthermore, a leaky‐integrate‐and‐fire (LIF) neuron is simulated using a circuit constructed with second‐order memristors. Taking the advantage of the LIF neuron, various neuromimetic dynamic processes, including local graded potential leaking out, postsynaptic impulse generation and backpropagation, and synaptic weight modification according to the suppression triplet‐STDP rule, are realized. The realized weight‐dependent pair‐ and triplet‐STDP rules are clearly in line with findings in biology. The physically realized triplet‐STDP rule is powerful in developing direction and speed selectivity for complex pattern recognition and tracking tasks. These scalable artificial synapses and neurons realized in second‐order memristors can intrinsically capture the neuromimetic dynamic processes; they are the promising building blocks for constructing brain‐inspired computation systems. [ABSTRACT FROM AUTHOR]

Memristors have emerged as promising candidates for artificial synaptic devices, serving as the building block of brain-inspired neuromorphic computing. In this letter, we developed a Pt/HfOx/Ti memristor with nonvolatile multilevel resistive switching behaviors due to the evolution of the conductive filaments and the variation in the Schottky barrier. Diverse state-dependent spike-timing-dependent-plasticity (STDP) functions were implemented with different initial resistance states. The measured STDP forms were adopted as the learning rule for a three-layer spiking neural network which achieves a 75.74% recognition accuracy for MNIST handwritten digit dataset. This work has shown the capability of memristive synapse in spiking neural networks for pattern recognition application. [ABSTRACT FROM AUTHOR]

Resistive random access memory (RRAM) based reconfigurable logic provides a temporal programmable dimension to realize Boolean logic functions and is regarded as a promising route to build non-von Neumann computing architecture. In this work, a reconfigurable operation method is proposed to perform nonvolatile sequential logic in a HfO 2 -based RRAM array. Eight kinds of Boolean logic functions can be implemented within the same hardware fabrics. During the logic computing processes, the RRAM devices in an array are flexibly configured in a bipolar or complementary structure. The validity was demonstrated by experimentally implemented NAND and XOR logic functions and a theoretically designed 1-bit full adder. With the trade-off between temporal and spatial computing complexity, our method makes better use of limited computing resources, thus provides an attractive scheme for the construction of logic-in-memory systems.

Objective: To compare the effective power of external chest compression and degree of exhaustion of rescue crew using different methods of counting, in order to establish a more appropriate and standard method of counting., Methods: Forty-eight subjects who had received formal training in basic life support (BLS) and advanced life support (ALS) were recruited randomly from doctors and nurses working in the emergency departments. The methods of counting were randomly selected which was performed first, and then they performed continuous chest compressions for 3 minutes using two different methods of counting with 30 minutes apart on the manikin, which was used in the hospital for cardiopulmonary resuscitation (CPR) training. The total number of compressions was recorded, and the number of those which were considered satisfactory, the peak heart rate of the performer and the time to reach peak heart were all recorded. Feeling of fatigue and discomfort was evaluated by self-reported survey results with the use of a visual analogue scale (VAS)., Results: The total number of compressions attempted, the effective power of external chest compression and the mean compression depth when rescuers counted form 1 to 10, which were repeated for 3 times, were greater than those when rescuers counted from 1 to 30 during 3 minutes of CPR [(202.40+/-6.52) times vs. (173.50+/-5.68) times, (67.48+/-2.00)% vs. (57.81+/-2.00)%, (4.45+/-0/.34) cm vs. (4.05+/0.21) cm, all P<0.01]. The VAS scores (22.15+/-3.09) was lower than that when rescuers counted them from 1 to 30 (31.10+/-4.09, P<0.01). The time to reach peak heart rate [(124.88+/-5.40) s] was longer than that when rescuers counted them from 1 to 30 [(106.15+/-6.80) s, P<0.01]. There was no difference in peak heart rate between two methods of counting., Conclusion: The effective power of external chest compression is greater when rescuers counted from 1 to 10 with repetition for 3 times than that when rescuers counted continuously from 1 to 30 during CPR. The method of counting from 1 to 10 with repetition for 3 times can save physical energy of rescue crew, so it can improve the quality of CPR to some extent.

Objective: To investigate the nature of syndrome of traditional Chinese medicine by means of pharmacokinetic (PK) method., Methods: Twenty-one healthy volunteers, 20 patients with syndrome of stagnation of liver qi and spleen deficiency, 22 patients with syndrome of deficiency of spleen qi and 19 patients with syndrome of excess of stomach heat were included and administered to take Jiawei Xiaoyaosan Recipe (JWXYSR). The serum PK parameters of ferulic acid (FA) were examined by high performance liquid chromatography (HPLC) method., Results: The absorption rate constant (alpha) and the elimination rate constant (beta) were both decreased while the apparent first-order absorption constant (K(a)) was enhanced significantly in the patients with syndrome of deficiency of spleen qi; the alpha, beta and Ka were all reduced in the patients with syndrome of stagnation of liver qi and spleen deficiency; the beta and K(a) were increased in the patients with syndrome of excess of stomach heat, as compared with the corresponding PK parameters in the healthy volunteers (P<0.01)., Conclusion: The PK analysis of FA in the patients with syndrome of deficiency of spleen qi shows that the absorption rate is accelerated, and both the distribution and elimination rates are slowed down. The absorption, distribution and elimination rates of AF are all slowed down in the patients with syndrome of stagnation of liver-qi and spleen deficiency, while the absorption and elimination rates of AF are both accelerated in the patients with syndrome of excess of stomach heat. There are obvious differences in the PK characteristics among these three syndromes.