Development and testing of an experimental power system fault demonstrator

In this paper a laboratory demonstrator for the study of power system faults is described. The facility has been developed in order to experimentally investigate a number of fault location and power system protection technologies developed by the authors and their colleagues at higher power levels and with more representative system parameters than has previ¬ously been possible. In addition to describing the facility itself, this paper also describes the validation of a previously studied method using the new demonstrato

Glycine and hyperammonemia : potential target for the treatment of hepatic encephalopathy

Hepatic encephalopathy (HE) is a neuropsychiatric disorder caused by hepatic dysfunction. Numerous studies dictate that ammonia plays an important role in the pathogenesis of HE, and hyperammonemia can lead to alterations in amino acid homeostasis. Glutamine and glycine are both ammoniagenic amino acids that are increased in liver failure. Modulating the levels of glutamine and glycine has shown to reduce ammonia concentration in hyperammonemia. Ornithine Phenylacetate (OP) has consistently been shown to reduce arterial ammonia levels in liver failure by modulating glutamine levels. In addition to this, OP has also been found to modulate glycine concentration providing an additional ammonia removing effect. Data support that glycine also serves an important role in N-methyl D-aspartate (NMDA) receptor mediated neurotransmission in HE. This potential important role for glycine in the pathogenesis of HE merits further investigations

Soluble tau species, not neurofibrillary aggregates, disrupt neural system integration in a tau transgenic model

Neurofibrillary tangles are a feature of Alzheimer disease and other tauopathies, and while they are generally believed to be markers of neuronal pathology, there is little evidence evaluating whether tangles directly impact neuronal function. To investigate the response of cells in hippocampal circuits to complex behavioral stimuli, we used an environmental enrichment paradigm to induce expression of an immediate-early gene, Arc, in the rTg4510 mouse model of tauopathy. These mice reversibly overexpress P301L tau and exhibit substantial neurofibrillary tangle deposition, neuronal loss, and memory deficits. Employing fluorescent in situ hybridization to detect Arc mRNA, we found that rTg4510 mice have impaired hippocampal Arc expression both without stimulation and in response to environmental enrichment; this likely reflects the combination of functional impairments of existing neurons and loss of neurons. However, tangle-bearing cells were at least as likely as non-tangle-bearing neurons to exhibit Arc expression in response to enrichment. Transgene suppression with doxycycline for 6 weeks resulted in increased percentages of Arc-positive cells in rTg4510 brains compared to untreated transgenics, restoring enrichment-induced Arc mRNA levels to that of wild-type controls despite the continued presence of neurofibrillary pathology. We interpret these data to indicate that soluble tau contributes to impairment of hippocampal function, while tangles do not preclude neurons from responding in a functional circuit

Influence of an inverter based DG on a double-ended fault location scheme

This paper describes the influence of Distributed Generation (DG) on a double ended fault location based on measuring the high frequency fault transients. The additional non-fundamental frequency current components from DG will influence the accuracy of an impedance based fault location technique based on non-fundamental frequencies. A double-ended impedance based fault location technique that utilizes the high frequency content (up to 5 kHz) is studied. The study showed that double-ended method is still able to locate a fault with a maximum error of 4% compared to the case without DG which showed a percentage error up to 2%

The Portacaval‐shunted rat : a new model for the study of the mechanisms controlling voluntary ethanol consumption and ethanol preference?

Portacaval anastomosis (PCA) is a surgical procedure whereby blood from the portal vein is shunted into the inferior vena cava. PCA in the rat results in a significant increase (from 0.77 ± 0.26 to 3.51 ± 0.37 g of ethanol/kg/day) in voluntary ethanol consumption in a free‐choice paradigm between water and 5% ethanol solution. After PCA surgery, increased voluntary ethanol consumption starts abruptly at 6 to 7 days and is maintained for > 28 weeks. Voluntary ethanol consumption in rats after PCA results in blood ethanol levels up to 158 mg%. After PCA, the ethanol preference ratio (defined as the percentage of total fluid intake constituted by ethanol) increased from 19 ± 2% to 78 ± 2% (p < 0.001). Administration of the nonselective opioid receptor antagonist naloxone (5 mg/kg, sc) resulted in a significant 6‐fold attenuation of voluntary ethanol consumption by rats with PCA, an effect that was not mediated by an effect on locomotor activity. These findings, together with previous reports of widespread alterations of the μ‐ and δ‐opioid receptors in the brain after PCA, suggest that increased voluntary ethanol consumption and ethanol preference in PCA rats may result from activation of the endogenous opioid system. Preliminary studies suggest that rats with PCA manifest behavioral signs consistent with the development of dependence. The portacaval‐shunted rat may provide a useful preparation for the study of mechanisms, in particular those involving the liver, implicated in the development of increased voluntary ethanol consumption and ethanol preference

Evaluating Resident Education Practices in Endoscopic Sinus Surgery

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Bayesian Optimised Collection Strategies for Fatigue Testing : Constant Life Testing

This paper presents a statistical framework enabling optimal sampling and robust analysis of fatigue data. We create protocols using Bayesian maximum entropy sampling, which build on the staircase and step methods, removing the requirement of prior knowledge of the fatigue strength distribution for data collection. Results show improved sampling efficiency and parameter estimation over the conventional approaches. Statistical methods for distinguishing between distribution types highlight the role of the protocol in model distinction. Experimental validation of the above work is performed, showing the applicability of the methods in laboratory testing.Comment: 25 pages, 12 figures + 1 SI figur

Intelligent impedance based fault-location for zonal power systems

A laboratory based demonstrator has been constructed to study the Active Impedance Estimation (AIE) technique as a means of locating faults on a power system. The demonstrator has been used to verify results from simulation experimentally. The AIE system and associated signal processing are presented and some of the issues that have been encountered are discussed. The presented simulation and experimental results presented both validate the method used