Antagonist conditioning contractions impair agonist functioning

This study assessed the effect of antagonist conditioning contractions (ACC) on the subsequent force and electromyography of an agonist. Twelve subjects performed isokinetic elbow flexion on a dynamometer in 4 test conditions including a baseline condition without, and 1, 3 and 6 seconds after, isometric triceps extension. Average peak torque (T), peak torque/body weight (T:BW), average power (P), and rate of torque development (RTD) were assessed. Electromyographic data were obtained from elbow extensors and flexors. A repeated measures ANOVA with post hoc analysis demonstrated that T, T:BW, P, and RTD were higher in the baseline, compared to the post ACC conditions (P ≤ 0.05), and appears to be due to higher brachioradialis activation in the baseline condition in compared to some post ACC conditions (P ≤ 0.05)

Model predictive control of an on-board fast battery charger for electric mobility applications

Under the necessities of reducing emissions and air pollution, and also for increasing fuel economy, automotive companies have been developing electric and plug-in hybrid electric vehicles. Since these vehicles are parked when the batteries are being charged, it is possible to use the traction power converter as on-board charger, also allowing to reduce weight, volume and costs of components in the vehicle. In this context, this paper presents a model predictive control algorithm for an on-board fast battery charging that uses the traction power converter of an electric vehicle. Simulation results and system implementation are depicted, and finally, are presented some experimental results obtained with the proposed control system.(undefined)info:eu-repo/semantics/publishedVersio

Model predictive control of an on-board fast battery charger for electric mobility applications

Under the necessities of reducing emissions and air pollution, and also for increasing fuel economy, automotive companies have been developing electric and plug-in hybrid electric vehicles. Since these vehicles are parked when the batteries are being charged, it is possible to use the traction power converter as on-board charger, also allowing to reduce weight, volume and costs of components in the vehicle. In this context, this paper presents a model predictive control algorithm for an on-board fast battery charging that uses the traction power converter of an electric vehicle. Simulation results and system implementation are depicted, and finally, are presented some experimental results obtained with the proposed control system.(undefined)info:eu-repo/semantics/publishedVersio

Southwest Research Institute assistance to NASA in biomedical areas of the technology utilization program

The activities are reported of the NASA Biomedical Applications Team at Southwest Research Institute between 25 August, 1972 and 15 November, 1973. The program background and methodology are discussed along with the technology applications, and biomedical community impacts

Stressor-Induced Increase in Muscle Fatigability of Young Men and Women is Predicted by Strength but Not Voluntary Activation

This study investigated mechanisms for the stressor-induced changes in muscle fatigability in men and women. Participants performed an isometric-fatiguing contraction at 20% maximal voluntary contraction (MVC) until failure with the elbow flexor muscles. Study one (n = 55; 29 women) involved two experimental sessions: 1) a high-stressor session that required a difficult mental-math task before and during a fatiguing contraction and 2) a control session with no mental math. For some participants (n = 28; 14 women), cortical stimulation was used to examine mechanisms that contributed to muscle fatigability during the high-stressor and control sessions. Study two (n = 23; nine women) determined the influence of a low stressor, i.e., a simple mental-math task, on muscle fatigability. In study one, the time-to-task failure was less for the high-stressor session than control (P \u3c 0.05) for women (19.4%) and men (9.5%): the sex difference response disappeared when covaried for initial strength (MVC). MVC force, voluntary activation, and peak-twitch amplitude decreased similarly for the control and high-stressor sessions (P \u3c 0.05). In study two, the time-to-task failure of men or women was not influenced by the low stressor (P \u3e 0.05). The greater fatigability, when exposed to a high stressor during a low-force task, was not exclusive to women but involved a strength-related mechanism in both weaker men and women that accelerated declines in voluntary activation and slowing of contractile properties

Stressor-Induced Increase in Muscle Fatigability of Young Men and Women is Predicted by Strength but Not Voluntary Activation

This study investigated mechanisms for the stressor-induced changes in muscle fatigability in men and women. Participants performed an isometric-fatiguing contraction at 20% maximal voluntary contraction (MVC) until failure with the elbow flexor muscles. Study one (n = 55; 29 women) involved two experimental sessions: 1) a high-stressor session that required a difficult mental-math task before and during a fatiguing contraction and 2) a control session with no mental math. For some participants (n = 28; 14 women), cortical stimulation was used to examine mechanisms that contributed to muscle fatigability during the high-stressor and control sessions. Study two (n = 23; nine women) determined the influence of a low stressor, i.e., a simple mental-math task, on muscle fatigability. In study one, the time-to-task failure was less for the high-stressor session than control (P \u3c 0.05) for women (19.4%) and men (9.5%): the sex difference response disappeared when covaried for initial strength (MVC). MVC force, voluntary activation, and peak-twitch amplitude decreased similarly for the control and high-stressor sessions (P \u3c 0.05). In study two, the time-to-task failure of men or women was not influenced by the low stressor (P \u3e 0.05). The greater fatigability, when exposed to a high stressor during a low-force task, was not exclusive to women but involved a strength-related mechanism in both weaker men and women that accelerated declines in voluntary activation and slowing of contractile properties

Memristive neural network for on-line learning and tracking with brain-inspired spike timing dependent plasticity

Brain-inspired computation can revolutionize information technology by introducing machines capable of recognizing patterns (images, speech, video) and interacting with the external world in a cognitive, humanlike way. Achieving this goal requires first to gain a detailed understanding of the brain operation, and second to identify a scalable microelectronic technology capable of reproducing some of the inherent functions of the human brain, such as the high synaptic connectivity (~104) and the peculiar time-dependent synaptic plasticity. Here we demonstrate unsupervised learning and tracking in a spiking neural network with memristive synapses, where synaptic weights are updated via brain-inspired spike timing dependent plasticity (STDP). The synaptic conductance is updated by the local time-dependent superposition of pre-and post-synaptic spikes within a hybrid one-transistor/one-resistor (1T1R) memristive synapse. Only 2 synaptic states, namely the low resistance state (LRS) and the high resistance state (HRS), are sufficient to learn and recognize patterns. Unsupervised learning of a static pattern and tracking of a dynamic pattern of up to 4 Ã\u97 4 pixels are demonstrated, paving the way for intelligent hardware technology with up-scaled memristive neural networks

Profiles of VGF peptides in the rat brain and their modulations after Phencyclidine treatment

From the VGF precursor protein originate several low molecular weight peptides, whose distribution in the brain and blood circulation is not entirely known. Among the VGF peptides, those containing the N-terminus portion were altered in the cerebro-spinal fluid (CSF) and hypothalamus of schizophrenia patients. "Hence, we aimed to better investigate the involvement of the VGF peptides in schizophrenia by studying their localization in the brain regions relevant for the disease, and revealing their possible modulations in response to certain neuronal alterations occurring in schizophrenia". We produced antibodies against different VGF peptides encompassing the N-terminus, but also C-terminus-, TLQP-, GGGE- peptide sequences, and the so named NERP-3 and -4. These antibodies were used to carry out specific ELISA and immunolocalization studies while mass spectrometry (MS) analysis was also performed to recognize the intact brain VGF fragments. We used a schizophrenia rat model, in which alterations in the prepulse inhibition (PPI) of the acoustic startle response occurred after PCP treatment. In normal rats, all the VGF peptides studied were distributed in the brain areas examined including hypothalamus, prefrontal cortex, hippocampus, accumbens and amygdaloid nuclei and also in the plasma. By liquid chromatography-high resolution mass, we identified different intact VGF peptide fragments, including those encompassing the N-terminus and the NERPs. PCP treatment caused behavioral changes that closely mimic schizophrenia, estimated by us as a disruption of PPI of the acoustic startle response. The PCP treatment also induced selective changes in the VGF peptide levels within certain brain areas. Indeed, an increase in VGF C-terminus and TLQP peptides was revealed in the prefrontal cortex (p < 0.01) where they were localized within parvoalbumin and tyrosine hydroxylase (TH) containing neurons, respectively. Conversely, in the nucleus accumbens, PCP treatment produced a down-regulation in the levels of VGF C-terminus-, N-terminus- and GGGE- peptides (p < 0.01), expressed in GABAergic- (C-terminus/GGGE) and somatostatin- (N-terminus) neurons. These results confirm that VGF peptides are widely distributed in the brain and modulated in specific areas involved in schizophreni