Search

Electric power distribution systems of many commercial and industrial sites often employ variable frequency drives and other loads that internally utilize dc. Such loads are often based on front-end line-commutated rectifiers. The detailed switch-level models of such rectifier systems can be readily implemented using a number of widely available digital programs and transient simulation tools, including the Electromagnetic Transient (EMT)-based programs and Matlab/Simulink. To improve the simulation efficiency for the system-level transient studies with a large number of such subsystems, the so-called dynamic average models have been utilized. This paper presents the average-value modeling methodologies for the conventional three-phase (six-pulse) front-end rectifier loads. We demonstrate the system operation and the dynamic performance of the developed average models in discontinuous and continuous modes, as well as under balanced and unbalanced operation. [ABSTRACT FROM PUBLISHER]

Stimulus-induced narrow-band gamma oscillations (20-70 Hz) are induced in the visual areas of the brain when particular visual stimuli, such as bars, gratings, or full-screen hue, are shown to the subject. Such oscillations are modulated by higher cognitive functions, like attention, and working memory, and have been shown to be abnormal in certain neuropsychiatric disorders, such as schizophrenia, autism, and Alzheimer's disease. However, although electroencephalogram (EEG) remains one of the most non-invasive, inexpensive, and accessible methods to record brain signals, some studies have failed to observe discernable gamma oscillations in human EEG. In this manuscript, we have described in detail a protocol to elicit robust gamma oscillations in human EEG. We believe that our protocol could help in developing non-invasive gamma-based biomarkers in human EEG, for the early detection of neuropsychiatric disorders., Competing Interests: Competing interestsThe authors declare no competing financial interests., (Copyright © The Authors; exclusive licensee Bio-protocol LLC.)

Gamma rhythms (~20-70 ​Hz) are abnormal in mental disorders such as autism and schizophrenia in humans, and Alzheimer's disease (AD) models in rodents. However, the effect of normal aging on these oscillations is unknown, especially for elderly subjects in whom AD is most prevalent. In a first large-scale (236 subjects; 104 females) electroencephalogram (EEG) study on gamma oscillations in elderly subjects (aged 50-88 years), we presented full-screen visual Cartesian gratings that induced two distinct gamma oscillations (slow: 20-34 ​Hz and fast: 36-66 ​Hz). Power decreased with age for gamma, but not alpha (8-12 ​Hz). Reduction was more salient for fast gamma than slow. Center frequency also decreased with age for both gamma rhythms. The results were independent of microsaccades, pupillary reactivity to stimulus, and variations in power spectral density with age. Steady-state visual evoked potentials (SSVEPs) at 32 ​Hz also reduced with age. These results are crucial for developing gamma/SSVEP-based biomarkers of cognitive decline in elderly., Competing Interests: Declaration of competing interest The authors declare no competing financial interests., (Copyright © 2020 The Author(s). Published by Elsevier Inc. All rights reserved.)

Reproductive factors are not considered to play a significant role in the aetiology of breast cancer in low incidence regions like Gujarat, although it is well established that they exert a major influence on such tumours in the western developed world. Women in the western Indian region have a very low prevalence of smoking, alcohol consumption but a high prevalence of vegetarianism. Noting the changes in the life style practices with increasing affluence is likely to yield several interesting findings in such a population. Physical activity and dietary factors have emerged as important parameters and their lack may contribute significantly to the risk of breast cancers. The breast cancer risk significantly increased with higher consumption of total fat (>25% of total calories), frequent intake of fried foods and sweets. A significant protection was offered by frequent consumption of green yellow leafy vegetables, foods rich in b-carotene and isoflavonoids. The present study demonstrated a good protective effect of dietary intake of antioxidant vitamins. The breast cancer risk increases with elevation of circulating lipid components except HDL-cholesterol.