Search results for "current"

Improved Switching Strategy for Selective Harmonic Elimination in DC-AC Signal Generation via Pulse-Width Modulation

2013

Published version of an article in the journal: Abstract and Applied Analysis. Also available from the publisher at: http://dx.doi.org/10.1155/2013/870904 Open Access We present an advanced design methodology for pulse-width-modulated (PWM) DC-AC signal generation. Using design methods based on the Walsh transform, AC sinusoidal signals can be approximated by suitable PWM signals. For different AC amplitudes, the switching instants of the PWM signals can be efficiently computed by using appropriate systems of explicit linear equations. However, the equation systems provided by conventional implementations of this approach are typically only valid for a restricted interval of AC amplitudes a…

Determination of trace elements in water by metal chelate capillary gas chromatography

1981

A redox-sensitive nanofluidic diode based on nicotinamide-modified asymmetric nanopores

2017

[EN] We demonstrate a redox-sensitive nanofluidic diode whose ion rectification is modulated by the oxidation and reduction of chemical moieties incorporated on its surface. To achieve this goal, we have first synthesized the chemical compounds 1-(4-aminobutyl)-3-carbamoylpyridin-1-ium (Nic-BuNH2) and 3-carbamoyl-1-(2,4-dinitrophenyl)pyridinium (Nic-DNP). Then, the surface of track-etched single asymmetric nanopores is decorated with the redox-sensitive Nic-BuNH2 and Nic-DNP molecules using carbodiimide coupling chemistry and Zincke reaction, respectively. The success of the modification reactions is monitored through the changes in the current¿voltage (I¿V) curves prior to and after pore f…

Transcranial Direct Current Stimulation in Post-Stroke Aphasia Rehabilitation: Bilateral vs Unilateral Online Stimulation

2017

Here we aim to evaluate the efficacy of repeated sessions of transcranial Direct Current Stimulation (tDCS) as additional treatment to standard behavioural rehabilitation in post-stroke aphasic patients comparing bilateral with unilateral left-sided and sham-tDCS. Background: Aphasia is the most common post-stroke cognitive disorder and it severely impacts activities of daily living and social interactions. tDCS recently showed good results in post-stroke aphasia rehabilitiation, even if no agreement at now exists about the stimulation parameters to employ to achieve the best rehabilitative outcome. Design/Methods: We enrolled twenty-two patients with single left-brain lesion at CT or MRI s…

Transcranial alternating current stimulation and sports performance: an explorative study of the association with the genetic background

2017

Brain stimulation in migraine

2013

Migraine is a very prevalent disease with great individual disability and socioeconomic burden. Despite intensive research effort in recent years, the etiopathogenesis of the disease remains to be elucidated. Recently, much importance has been given to mechanisms underlying the cortical excitability that has been suggested to be dysfunctional in migraine. In recent years, noninvasive brain stimulation techniques based on magnetic fields (transcranial magnetic stimulation, TMS) and on direct electrical currents (transcranial direct current stimulation, tDCS) have been shown to be safe and effective tools to explore the issue of cortical excitability, activation, and plasticity in migraine. M…

Resting state FMRI: A tool to investigate functional connectivity modulation induced by transcranial direct current stimulation of the motor network

2016

Introduction: Resting-state functional connectivity (fcMRI) represents a novel fMRI approach that allows detection of temporal correlations in spontaneous BOLD signal oscillations while subjects rest quietly in the scanner. Under resting conditions the brain is engaged in spontaneous activity that causes a low frequencies (<0.1 Hz) BOLD signal fluctuations. Functional connectivity (FC) can be defined as the synchrony of neural activity among spatially distant regions. Transcranial direct current stimulation (tDCS) is a non-invasive brain stimulation technique that is known to modulate cortical activity and FC among brain regions, as measured by functional magnetic resonance imaging. This st…

P 56 tDCS shows no effects on motor cortex excitability at rest

2017

Introduction Transcranial direct current stimulation (tDCS) is a widely used technique in research and clinics. However, the underlying physiological mechanisms are not yet clear. Modeling studies suggest that the electric field during tDCS is dominated by a tangential component which predominantly modifies active synaptic connections ( Radman et al., 2007 ). We have previously shown that tDCS with an increased tangential compared to the conventional montage introduced by Nitsche and Paulus (2000) , suppresses the effects of paired associative stimulation of the supplementary motor area and the primary motor cortex (PASSMA-M1) independent of tDCS polarity (Faber et al., under submission). H…

2019

Today, several pharmaceutic and non-pharmaceutic approaches exist to treat psychiatric and neurological diseases. Because of the lack of treatment procedures that are medication free and without severe side effects, transcranial direct current stimulation (tDCS) and aerobic exercise (AE) have been tested to explore the potential for initiating and modulating neuroplasticity in the human brain. Both tDCS and AE could support cognition and behavior in the clinical and non-clinical context to improve the recovery process within neurological or psychiatric conditions or to increase performance. As these techniques still lack meaningful effects, although they provide multiple beneficial opportun…

Current-Based Measurement Technique for High Sensitivity Detection of Resistive Bridges With External Balancing Through Control Voltages

2017

We present a novel approach based on differential measurements of dc currents with very high sensitivity suitable for the detection of very small variations of resistors in Wheatstone full-bridge configurations. External control voltages allow for the compensation of the bridge unbalancing avoiding the need of changing its elements so making the solution suitable for integrated sensor systems. The proposed current-based measurement technique has been implemented through three different circuits, in transimpedance configuration and without the use of any further amplification stage, employing only two active blocks that allow for a very high integration level. The main characteristics of the…