Search Results (4)

The main advantages of spiking neural networks are the high biological plausibility and their fast response due to spiking behaviour. The response time decreases significantly in the hardware implementation of SNN because the neurons operate in parallel. Compared with the traditional computational neural network, the SNN use a lower number of neurons, which also reduces their cost. Another critical characteristic of SNN is their ability to learn by event association that is determined mainly by postsynaptic mechanisms such as long-term potentiation. However, in some conditions, presynaptic plasticity determined by post-tetanic potentiation occurs due to the fast activation of presynaptic neurons. This violates the Hebbian learning rules that are specific to postsynaptic plasticity. Hebbian learning improves the SNN ability to discriminate the neural paths trained by the temporal association of events, which is the key element of learning in the brain. This paper quantifies the efficiency of Hebbian learning as the ratio between the LTP and PTP effects on the synaptic weights. On the basis of this new idea, this work evaluates for the first time the influence of the number of neurons on the PTP/LTP ratio and consequently on the Hebbian learning efficiency. The evaluation was performed by simulating a neuron model that was successfully tested in control applications. The results show that the firing rate of postsynaptic neurons $post$ depends on the number of presynaptic neurons $pre$, which increases the effect of LTP on the synaptic potentiation. When $post$ activates at a requested rate, the learning efficiency varies in the opposite direction with the number of $pres$, reaching its maximum when fewer than two $pres$ are used. In addition, Hebbian learning is more efficient at lower presynaptic firing rates that are divisors of the target frequency of $post$. This study concluded that, when the electronic neurons additionally model presynaptic plasticity to LTP, the efficiency of Hebbian learning is higher when fewer neurons are used. This result strengthens the observations of our previous research where the SNN with a reduced number of neurons could successfully learn to control the motion of robotic fingers. Full article

This experiment evaluated the effects of various vermicompost amounts (0%, 10%, 20%, 25%, and 50%) of the total weight of the mixture of soil and vermicompost) and red worms (0, 10, and 20 individuals/pot) on carrot phytomass and macroelements concentration when applied to soil. Increasing the quantity of vermicompost (Vc) raised the weight of carrot roots and leaves. When we increased the dose of Vc, differences in phytomass growth were diminished gradually. Fifty percent of Vc in the soil did not have a negative impact on the formation of carrot roots and leaves. Vc increased the water content in roots and decreased it in leaves. Earthworms (EWs) in soil increased the weight of both carrot roots and leaves. The positive impact of EW on roots and leaves was higher when the vermicompost content in the soil was lower. EWs showed positive effects on the potassium concentration in whole carrot phytomass. Both EWs and Vc increased the value of the tetanic ratio in the carrot roots, which lowers their quality. EWs showed positive effects on the potassium concentration in whole carrot phytomass. Relationships found between K × Ca and Mg × S were antagonistic. Positive dependencies were detected between the carrot root yield and N, P, K concentration in both leaves and roots. Full article

The influence of the degree of a neuromuscular block (NMB) on surgical operating conditions during laparoscopic surgery is debated controversially. The extent of abdominal distension during the time course of the NMB was assessed as a new measurement tool. In 60 patients scheduled for gynecologic laparoscopic surgery, the increase of the abdominal wall length induced by the capnoperitoneum was measured at 5 degrees of the NMB: intense NMB—post-tetanic count (PTC) = 0; deep NMB—train-of-four count (TOF) = 0 and PTC = 1–5; medium NMB—PTC > 5 and TOF = 0–1; shallow NMB—TOF > 1; full recovery—train-of-four ratio TOFR > 90%. Simultaneously, the quality of operating conditions was assessed with a standardized rating scale (SRS) reaching from 1 (extremely poor conditions) to 5 (excellent conditions). Fifty patients could be included in the analysis. The abdominal wall length increased by 10–13 mm induced by the capnoperitoneum. SRS was higher during intense NMB (4.7 ± 0.5) vs. full recovery (4.5 ± 0.5) (mean ± SD; p = 0.025). Generally, an intense NMB did not increase abdominal wall length induced by capnoperitoneum. Additionally, its influence on the quality of surgical operating conditions seems to be of minor clinical relevance. Full article

The consequences of two-week hindlimb suspension (HS) on skeletal muscle atrophy were investigated in balanced diet-fed Fat-1 transgenic and C57BL/6 wild-type mice. Body composition and gastrocnemius fatty acid composition were measured. Skeletal muscle force, cross-sectional area (CSA), and signaling pathways associated with protein synthesis (protein kinase B, Akt; ribosomal protein S6, S6, eukaryotic translation initiation factor 4E-binding protein 1, 4EBP1; glycogen synthase kinase3-beta, GSK3-beta; and extracellular-signal-regulated kinases 1/2, ERK 1/2) and protein degradation (atrophy gene-1/muscle atrophy F-box, atrogin-1/MAFbx and muscle RING finger 1, MuRF1) were evaluated in the soleus muscle. HS decreased soleus muscle wet and dry weights (by 43% and 26%, respectively), muscle isotonic and tetanic force (by 29% and 18%, respectively), CSA of the soleus muscle (by 36%), and soleus muscle fibers (by 45%). Fat-1 transgenic mice had a decrease in the ω-6/ω-3 polyunsaturated fatty acids (PUFAs) ratio as compared with C57BL/6 wild-type mice (56%, p < 0.001). Fat-1 mice had lower soleus muscle dry mass loss (by 10%) and preserved absolute isotonic force (by 17%) and CSA of the soleus muscle (by 28%) after HS as compared with C57BL/6 wild-type mice. p-GSK3B/GSK3B ratio was increased (by 70%) and MuRF-1 content decreased (by 50%) in the soleus muscle of Fat-1 mice after HS. Balanced diet-fed Fat-1 mice are able to preserve in part the soleus muscle mass, absolute isotonic force and CSA of the soleus muscle in a disuse condition. Full article