The objective of this project was to examine the influence of stimulus waveform and frequency on extracellular stimulation of neurons with their cell bodies near the electrode (local cells) and fibers of passage in the CNS. Detailed computer-based models of CNS cells and axons were developed that accurately reproduced the dynamic firing properties of mammalian motoneurons including afterpotenti...

1. Intracellular recording techniques were used to characterize synaptic inhibitory postsynaptic potentials (IPSPs) recorded from neurons of the basolateral nucleus of the amygdala (BLA). Bipolar electrodes positioned in the stria terminalis (ST) or lateral amygdala (LA) were used to evoke synaptic responses at a frequency of 0.25 Hz. 2. Two synaptic waveforms having IPSP components could be ev...

OBJECTIVES The goal of this study was to determine if the defibrillation threshold (DFT) after spontaneous ventricular fibrillation (VF) secondary to acute ischemia differs from the DFT for electrically induced VF in the absence of ischemia in anesthetized, closed-chest dogs and pigs. BACKGROUND The efficacy of external defibrillators has been tested mainly in animals and humans using E-VF, y...

During internal defibrillation, potential gradients greater than 100 V/cm occur near defibrillation electrodes. Such strong fields may cause deleterious effects, including arrhythmias. This study determined 1) the effects of such strong fields on the propagation of activation and 2) whether these effects were different for monophasic and biphasic shocks. Voltages and potential gradients during ...

This paper presents a new method to find the optimum switching angles in voltage source multilevel converters in order to minimize specific higher order harmonics and decrease the total harmonic distortion (THD) of their output voltage waveform. The output voltage waveform of inverter can either be in the form of staircase or PWM. In order to increase the degrees of freedom and elimination of m...

OBJECTIVE To determine the correlation of hepatic venous waveform changes with severity of hepatic dysfunction and grading of oesophageal varices. METHODS A cross-sectional analytical study was conducted at Jinnah Postgraduate Medical Centre, Karachi, Medical Unit-III, Ward-7 from January 2009 to December 2009. Cirrhotic patients with portal hypertension were included in study. Patients prese...