Experimental Investigation of the Effect of Transient Overvoltages on XLPE-insulated HVDC Cables

HVDC cables are subject to several types of impulses superimposed on the rated DC voltage during their service lifetime. Temporary Overvoltages (TOVs) and Superimposed Switching impulses (SSIs) are considered some of the most challenging due to the relatively long impulse duration. This paper aims at investigating experimentally the effect of TOVs and SSIs on XLPE insulation for extruded HVDC cables. 0.15-mm-thick DC-XLPE specimens, aged by applying TOVs and SSIs, are characterized using dielectric analyzer and Fourier Transform InfraRed spectroscopy (FTIR) to detect the aging effects on the insulation. Results show an increase in the imaginary part of permittivity, ε", accompanied with the appearance of additional dipolar polarization losses peaks. The amplitude and frequency of the aforementioned peaks vary with the amplitude and the number of applied TOVs and SSIs. An increase in electrical conductivity is also noticed with aging. FTIR results show absorbance peaks in the aged specimens likely due to the intramolecular bonds rupture accompanied with the formation of aging products. In summary, SSIs and TOVs cause a noticeable reduction of insulating properties in XLPE specimens. The higher the peak of the transient, the greater the aging effect

Neurogenesis in Neurotoxin-induced Animal Models for Parkinson’s Disease—A Review of the Current Status

Animal models for Parkinson’s disease (PD) are essential for understanding its pathogenesis and for development and testing of new therapies. Discoveries of endogenous neurogenesis in the adult mammalian brain give new insight into the cell-based approach for treatment of neurodegenerative disorders, such as PD. Although a great deal of interest has been focused on endogenous neurogenesis in neurotoxin-induced animal models for PD, it still remains controversial whether neural stem cells migrate into the injured area and contribute to repopulation of depleted dopaminergic neurons in neurotoxin-injured adult brains. The purpose of this review is to examine the data available regarding neurogenesis in neurotoxin-induced animal models of PD. It is hoped that data from the animal investigations available in the literature will promote understanding of the neurotoxin-induced animal models for PD

Environmental Factors and Students\u27 Learning Approaches: a Survey on Malaysian Polytechnics Students

Several studies have shown the impact of environmental factors on student learning approaches. Despite the importance of such studies, studies on technical learners are few. Thus, this study aimed to determine the influence of learning environment on Polytechnics students\u27 learning approaches in Malaysia. Learning environment plays an important role in the cognitive, effective and social domains of students because it could improve students\u27 learning outcomes. Learning approaches refer to the ways students deal with academic tasks that are related to learning outcomes. This study used Course Experience Questionnaire (CEQ) and Revised Two-Factor Study Process Questionnaire (RSPQ-2F) to collect the research data. Data were analyzed using AMOS Version 18. Multiple regressions were conducted to predict learning environment factors that influenced the level of students\u27 learning approaches. The result shows that effective teaching is a major factor that influences students\u27 deep approach followed by the assessment, learning resources and clear objectives

Procjena anthelmintičke učinkovitosti pripravaka albendazola i ivermektina u magaraca u Darfuru u Sudanu

The therapeutic efficacies of albendazole and ivermectin drench formulation at the manufacturer’s recommended dose were evaluated in a controlled trial in Nyala town, South Darfur State, Sudan. The study involved 24 donkeys naturally infected with gastrointestinal nematodes; they were divided into four groups of equal size. Albendazole was administered orally once at a dose rate of 10 mg/kg body mass, or twice, 14 days apart at dose rate of 10 mg/kg body mass. Ivermectin was administered orally as a single dose at 200 μg/kg body mass. Treatment efficacy was based on the mean faecal egg count reduction 14 days post treatment. A faecal egg count reduction of 100% was found after treatment with albendazole and ivermectin. In addition efficacy percentages of albendazole and ivermectin against immature and adult nematodes were as follows: Trichostrongylus axei 67.09% and 100%, Parascaris equorum 100% and 100%, Oxyuris equi 100% and 100%, Strongylus sp. 98.4% and 100%; and small strongyles 100% and 100%. Albendazole single and twice and ivermectin with the single dose showed moderate efficacy (33%, 59.08% and 62.71%, respectively) against larvae found in the cranial mesenteric artery aneurisms. No adverse reactions were observed in treated donkeys during the experiment period.Učinkovitost pripravaka albendazola i ivermektina u preporučenoj dozi istražena je u kontroliranom pokusu provedenom na magarcima u gradu Nyala u južnom Darfuru u Sudanu. Istraživanje je obuhvatilo 24 magarca prirodno invadirana želučanocrijevnim oblićima. Magarci su bili ravnomjerno raspoređeni u četiri skupine te peroralno liječeni albendazolom u dozi od 10 mg/kg tjelesne mase jednokratno ili dvokratno u razmaku od dva tjedna. Ivermektinom su liječeni peroralno i to jednokratno u dozi od 200 mg/kg tjelesne mase. Ljekovit učinak bio je određen na temelju smanjenja broja jaja u izmetu dva tjedna nakon liječenja. Dokazano je bilo 100%-tno smanjenje broja jaja nakon liječenja obama pripravcima. Učinkovitost je bila dokazana i postmortalnom parazitološkom pretragom i to prebrojavanjem nezrelih i odraslih oblića. U liječenih životinja ustanovljeno je 67,9% manje nezrelih te 100% manje odraslih oblića Trichostrongylus axei. Stopostotna učinkovitost bila je dokazana za nezrele i za zrele obliće Parascaris equorum, Oxyuris equi te male strongilide. Nešto manja učinkovitost (98,4%) bila je dokazana za nezrele obliće Strongylus sp. Kombinacija jednokratnoga i dvokratnoga davanja albendazola s jednokratnim davanjem ivermektina pokazala je prosječno dobru učinkovitost (33%, 59,08% i 62,71%) protiv ličinki u aneurizmama na području kranijalne mezenterijske arterije. U magaraca nisu bile primijećene nikakve nuspojave nakon primjene lijekova

Procjena anthelmintičke učinkovitosti pripravaka albendazola i ivermektina u magaraca u Darfuru u Sudanu

The therapeutic efficacies of albendazole and ivermectin drench formulation at the manufacturer’s recommended dose were evaluated in a controlled trial in Nyala town, South Darfur State, Sudan. The study involved 24 donkeys naturally infected with gastrointestinal nematodes; they were divided into four groups of equal size. Albendazole was administered orally once at a dose rate of 10 mg/kg body mass, or twice, 14 days apart at dose rate of 10 mg/kg body mass. Ivermectin was administered orally as a single dose at 200 μg/kg body mass. Treatment efficacy was based on the mean faecal egg count reduction 14 days post treatment. A faecal egg count reduction of 100% was found after treatment with albendazole and ivermectin. In addition efficacy percentages of albendazole and ivermectin against immature and adult nematodes were as follows: Trichostrongylus axei 67.09% and 100%, Parascaris equorum 100% and 100%, Oxyuris equi 100% and 100%, Strongylus sp. 98.4% and 100%; and small strongyles 100% and 100%. Albendazole single and twice and ivermectin with the single dose showed moderate efficacy (33%, 59.08% and 62.71%, respectively) against larvae found in the cranial mesenteric artery aneurisms. No adverse reactions were observed in treated donkeys during the experiment period.Učinkovitost pripravaka albendazola i ivermektina u preporučenoj dozi istražena je u kontroliranom pokusu provedenom na magarcima u gradu Nyala u južnom Darfuru u Sudanu. Istraživanje je obuhvatilo 24 magarca prirodno invadirana želučanocrijevnim oblićima. Magarci su bili ravnomjerno raspoređeni u četiri skupine te peroralno liječeni albendazolom u dozi od 10 mg/kg tjelesne mase jednokratno ili dvokratno u razmaku od dva tjedna. Ivermektinom su liječeni peroralno i to jednokratno u dozi od 200 mg/kg tjelesne mase. Ljekovit učinak bio je određen na temelju smanjenja broja jaja u izmetu dva tjedna nakon liječenja. Dokazano je bilo 100%-tno smanjenje broja jaja nakon liječenja obama pripravcima. Učinkovitost je bila dokazana i postmortalnom parazitološkom pretragom i to prebrojavanjem nezrelih i odraslih oblića. U liječenih životinja ustanovljeno je 67,9% manje nezrelih te 100% manje odraslih oblića Trichostrongylus axei. Stopostotna učinkovitost bila je dokazana za nezrele i za zrele obliće Parascaris equorum, Oxyuris equi te male strongilide. Nešto manja učinkovitost (98,4%) bila je dokazana za nezrele obliće Strongylus sp. Kombinacija jednokratnoga i dvokratnoga davanja albendazola s jednokratnim davanjem ivermektina pokazala je prosječno dobru učinkovitost (33%, 59,08% i 62,71%) protiv ličinki u aneurizmama na području kranijalne mezenterijske arterije. U magaraca nisu bile primijećene nikakve nuspojave nakon primjene lijekova

The non-Abelian gauge theory of matrix big bangs

We study at the classical and quantum mechanical level the time-dependent Yang-Mills theory that one obtains via the generalisation of discrete light-cone quantisation to singular homogeneous plane waves. The non-Abelian nature of this theory is known to be important for physics near the singularity, at least as far as the number of degrees of freedom is concerned. We will show that the quartic interaction is always subleading as one approaches the singularity and that close enough to t=0 the evolution is driven by the diverging tachyonic mass term. The evolution towards asymptotically flat space-time also reveals some surprising features.Comment: 29 pages, 8 eps figures, v2: minor changes, references added: v3 small typographical changes

Is neurogenesis reparative after status epilepticus?

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/65863/1/j.1528-1167.2007.01355.x.pd

Recurrence and higher ergodic properties for quenched random Lorentz tubes in dimension bigger than two

We consider the billiard dynamics in a non-compact set of R^d that is constructed as a bi-infinite chain of translated copies of the same d-dimensional polytope. A random configuration of semi-dispersing scatterers is placed in each copy. The ensemble of dynamical systems thus defined, one for each global realization of the scatterers, is called `quenched random Lorentz tube'. Under some fairly general conditions, we prove that every system in the ensemble is hyperbolic and almost every system is recurrent, ergodic, and enjoys some higher chaotic properties.Comment: Final version for J. Stat. Phys., 18 pages, 4 figure

An evaluation of kurtosis beamforming in magnetoencephalography to localize the epileptogenic zone in drug resistant epilepsy patients

OBJECTIVE: Kurtosis beamforming is a useful technique for analysing magnetoencephalograpy (MEG) data containing epileptic spikes. However, the implementation varies and few studies measure concordance with subsequently resected areas. We evaluated kurtosis beamforming as a means of localizing spikes in drug-resistant epilepsy patients. METHODS: We retrospectively applied kurtosis beamforming to MEG recordings of 22 epilepsy patients that had previously been analysed using equivalent current dipole (ECD) fitting. Virtual electrodes were placed in the kurtosis volumetric peaks and visually inspected to select a candidate source. The candidate sources were compared to the ECD localizations and resection areas. RESULTS: The kurtosis beamformer produced interpretable localizations in 18/22 patients, of which the candidate source coincided with the resection lobe in 9/13 seizure-free patients and in 3/5 patients with persistent seizures. The sublobar accuracy of the kurtosis beamformer with respect to the resection zone was higher than ECD (56% and 50%, respectively), however, ECD resulted in a higher lobar accuracy (75%, 67%). CONCLUSIONS: Kurtosis beamforming may provide additional value when spikes are not clearly discernible on the sensors and support ECD localizations when dipoles are scattered. SIGNIFICANCE: Kurtosis beamforming should be integrated with existing clinical protocols to assist in localizing the epileptogenic zone

Abolishing spontaneous epileptiform activity in human brain tissue through AMPA receptor inhibition

Objective: The amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid receptor (AMPAR) is increasingly recognized as a therapeutic target in drug-refractory pediatric epilepsy. Perampanel (PER) is a non-competitive AMPAR antagonist, and pre-clinical studies have shown the AMPAR-mediated anticonvulsant effects of decanoic acid (DEC), a major medium-chain fatty acid provided in the medium-chain triglyceride ketogenic diet. Methods: Using brain tissue resected from children with intractable epilepsy, we recorded the effects of PER and DEC in vitro. Results: We found resected pediatric epilepsy tissue exhibits spontaneous epileptic activity in vitro, and showed that DEC and PER inhibit this epileptiform activity in local field potential recordings as well as excitatory synaptic transmission. Interpretation: This study confirms AMPAR antagonists inhibit epileptiform discharges in brain tissue resected in a wide range of pediatric epilepsies