Home About us Contact
|
Home About us Contact | ||
|
|
||
High Amplitude (high + amplitude)
Selected AbstractsA new animal model of infantile spasms with unprovoked persistent seizuresEPILEPSIA, Issue 2 2008Chong L. Lee Summary Purpose: Infantile spasms is one of the most severe epileptic syndromes of infancy and early childhood. Progress toward understanding the pathophysiology of this disorder and the development of effective therapies has been hindered by the lack of a relevant animal model. We report here the creation of such a model. Methods: The sodium channel blocker, tetrodotoxin (TTX), was chronically infused into the developing neocortex or hippocampus of infant rats by way of an osmotic minipump starting on postnatal day 10,12. Results: After a minimum of 10 days of infusion, approximately one-third of these rats began to display very brief (1,2 s) spasms, which consisted of symmetric or asymmetric flexion or extension of the trunk and sometimes involvement of one or both forelimbs. The typical ictal EEG pattern associated with the behavioral spasms consisted of an initial generalized, high amplitude, slow wave followed by an electrodecrement with superimposed fast activity. The interictal EEG revealed multifocal spikes and sharp waves, and in most animals that had spasms a hypsarrhythmic pattern was seen, at least intermittently, during NREM sleep. Like in humans, the spasms in the rat often occurred in clusters especially during sleep,wake transitions. Comparison of the ictal and interictal EEGs recorded in this model and those from humans with infantile spasms revealed that the patterns and the frequency components of both the ictal events and hypsarrhythmia were very similar. Discussion: The TTX model of infantile spasms should be of value in furthering an understanding of the pathophysiology of this seizure disorder. [source] Cognitive function, P3a/P3b brain potentials, and cortical thickness in agingHUMAN BRAIN MAPPING, Issue 11 2007Anders M. Fjell Abstract The purpose of the study was to assess the relationship between the P3a/P3b brain potentials, cortical thickness, and cognitive function in aging. Thirty-five younger and 37 older healthy participants completed a visual three-stimuli oddball ERP (event-related potential)-paradigm, a battery of neuropsychological tests, and MRI scans. Groups with short vs. long latency, and low vs. high amplitude, were compared on a point by point basis across the entire cortical mantle. In the young, thickness was only weakly related to P3. In the elderly, P3a amplitude effects were found in parietal areas, the temporoparietal junction, and parts of the posterior cingulate cortex. P3b latency was especially related to cortical thickness in large frontal regions. Path models with the whole sample pooled together were constructed, demonstrating that cortical thickness in the temporoparietal cortex predicted P3a amplitude, which in turn predicted executive function, and that thickness in orbitofrontal cortex predicted P3b latency, which in turn predicted fluid function. When age was included in the model, the relationship between P3 and cognitive function vanished, while the relationship between regional cortical thickness and P3 remained. It is concluded that thickness in specific cortical areas correlates with scalp recorded P3a/P3b in elderly, and that these relationships differentially mediate higher cognitive function. Hum Brain Mapp 2007. © 2007 Wiley-Liss, Inc. [source] Dynamics of human neocortex that optimizes its stability and flexibilityINTERNATIONAL JOURNAL OF INTELLIGENT SYSTEMS, Issue 9 2006Walter J. Freeman The electroencephalogram (EEG) in states of awake, sleep, and seizure in a patient with intractable partial complex seizures was recorded through a 1- × 1-cm microgrid of 64 electrodes on the right inferior temporal gyrus during a week-long neurosurgical evaluation. Comparisons with a normal intracranial EEG were perforce from animals. Analytic phase and amplitude from the Hilbert transform gave the temporal resolution needed to resolve EEG spatiotemporal structure. The rest state revealed multiple overlapping patterns of high-frequency coherent oscillations resembling bubbles in boiling water. Bubble diameters gave estimates of the distances across the cortex over which the cortical oscillations were synchronized. Superimposed on these bubbles were large-sized epochs of phase locking with briefly constant frequency and high amplitude. These coordinated analytic phase differences occurred between short periods of high phase variance. The variance gave evidence for state transitions between transiently stable states with constant phase gradients. In sleep these phase patterns persisted with reduced amplitude, occasionally interrupted by long-lasting (,1 s) epochs with no spatial textures in phase and amplitude despite a large increase in amplitude. Seizures had high amplitude 3/s spikes with steep spatial gradients. Onset occurred after pre-ictal reduction in bubble diameters as evidence for large-scale cortical disintegration preceding loss of stability. © 2006 Wiley Periodicals, Inc. Int J Int Syst 21: 881,901, 2006. [source] Colonic motility in chronic ulcerative proctosigmoiditis and the effects of nicotine on colonic motility in patients and healthy subjectsALIMENTARY PHARMACOLOGY & THERAPEUTICS, Issue 5 2001B. Coulie Background: Nicotine decreases diarrhoea and pain in ulcerative colitis without reducing inflammation. Aims: (i) To evaluate the effect of ulcerative proctosigmoiditis on motor functions of an uninflamed segment of descending colon; and (ii) to assess nicotine's effects on colonic motor functions in patients and healthy subjects. Methods: In healthy subjects (n=30) and patients with ulcerative colitis (13; 11 active, two quiescent colitis), we studied the effects of intravenous nicotine on colonic transit of solid residue by scintigraphy (healthy subjects) and on colonic motility in healthy subjects and 11 patients. Results: In ulcerative colitis, fasting colonic motility was increased, whereas motor response to a meal was significantly reduced; compliance was unchanged. In healthy subjects, high-dose nicotine induced transient high amplitude propagated contractions and relaxation of the descending colon followed by decreased phasic contractions. This dose also accelerated colonic transit. Low-dose nicotine (mimicking a transdermal nicotine patch) reduced colonic compliance in healthy subjects, but did not affect motor function in ulcerative colitis. Conclusions: Ulcerative proctosigmoiditis increases fasting colonic motility and reduces tone response to a meal in the descending colon without affecting colonic compliance, suggesting changes in physiological responses but not intrinsic wall properties. Nicotine has dose-dependent effects on colonic motor activity in healthy subjects. [source] Spectral fitting: The extraction of crucial information from a spectrum and a spectral imageMAGNETIC RESONANCE IN MEDICINE, Issue 6 2003Colin Mailer Abstract A highly accurate line-width simulation computer program is used that can account for both high amplitude and frequency of the Zeeman modulation in an electron paramagnetic resonance (EPR) experiment. This allows for the overmodulation of EPR lines to increase signal-to-noise ratio (SNR) in EPR spectra and spectroscopic images, without any sacrifice in the determination of the intrinsic line width (1/, · T2e). The technique was applied to continuous-wave EPR spectroscopic images of a narrow, single-line trityl spin probe wherein a full EPR spectrum was extracted from each 3D spatial voxel. Typical improvements are a three- to fivefold increase in SNR in the high-gradient projections in the image and a reduction in the standard deviation (SD), by a factor of 3, of the line widths in the low-gradient domain. This method is a general one that is also applicable to the analysis of conventional 14N or 15N nitroxide spin probes. Magn Reson Med 49:1175,1180, 2003. © 2003 Wiley-Liss, Inc. [source] Luminous red galaxy clustering at z, 0.7 , first results using AAOmegaMONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, Issue 3 2008Nicholas P. Ross ABSTRACT We report on the AAT-AAOmega LRG Pilot observing run to establish the feasibility of a large spectroscopic survey using the new AAOmega instrument. We have selected luminous red galaxies (LRGs) using single epoch SDSS riz -photometry to i < 20.5 and z < 20.2. We have observed in three fields including the COSMOS field and the COMBO-17 S11 field, obtaining a sample of ,600 redshift z, 0.5 LRGs. Exposure times varied from 1,4 h to determine the minimum exposure for AAOmega to make an essentially complete LRG redshift survey in average conditions. We show that LRG redshifts to i < 20.5 can be measured in ,1.5 h exposures and present comparisons with 2SLAQ and COMBO-17 (photo)redshifts. Crucially, the riz selection coupled with the three to four times improved AAOmega throughput is shown to extend the LRG mean redshift from z= 0.55 for 2SLAQ to z= 0.681 ± 0.005 for riz -selected LRGs. This extended range is vital for maximizing the signal-to-noise ratio for the detection of the baryon acoustic oscillations (BAOs). Furthermore, we show that the amplitude of LRG clustering is s0= 9.9 ± 0.7h,1 Mpc, as high as that seen in the 2SLAQ LRG Survey. Consistent results for this clustering amplitude are found from the projected and semi-projected correlation functions. This high amplitude is consistent with a long-lived population whose bias evolves as predicted by a simple ,high-peak' model. We conclude that a redshift survey of 360 000 LRGs over 3000 deg2, with an effective volume some four times bigger than previously used to detect BAO with LRGs, is possible with AAOmega in 170 nights. [source] Evaluation of laparoscopic surgery for Hirschsprung's disease from the standpoint of invasiveness and colonic motility: Prolapsing technique with extra-anal mucosectomyASIAN JOURNAL OF ENDOSCOPIC SURGERY, Issue 3 2009Y Morikawa Abstract Objective: Laparoscopic pull-through has become the standard surgical modality for Hirschsprung's disease in the field of pediatric surgery. This article discusses the minimal invasiveness of the prolapsing technique. This technique allows mucosectomies to be performed under direct vision even at the deepest dissected portion because the procedure is conducted via an extra-anal approach. Method: The laparoscopic prolapsing technique (Lap) is compared with the conventional open Soave technique in terms of the change in CRP and WBC, defecation function, both clinical and manometric, after surgery. Results: As a result, the timing of surgery has become earlier and the patients younger. Soiling occurs in 33% of open Soave and 0% of Lap patients. Manometry after Lap. pull-through revealed a positive recto-anal inhibitory reflex in 39% and evoked high amplitude propagated contraction was demonstrated in 85% of patients. Conclusion: These results suggest that the present technique, including minimal dissections of the mesentery and the preservation of pelvic nerves in combination with fine mucosectomy under direct vision, could be beneficial for postoperative anorectal function in patients with Hirschspurung's disease. [source] Parsec-scale jet in the distant gigahertz-peaked spectrum quasar PKS 0858,279ASTRONOMISCHE NACHRICHTEN, Issue 2-3 2009Y. Y. KovalevArticle first published online: 13 FEB 200 Abstract The high redshift GPS quasar PKS 0858,279 exhibits the following properties which make the source unusual. Our RATAN-600 monitoring of 1,22 GHz spectrum has detected broad-band radio variability with high amplitude and relatively short time scale. In the same time, the milliarcsecond scale structure observed in a snapshot VLBA survey turned out to be very resolved which is not expected from the fast flux density variations. We performed 1.4,22 GHz VLBA observations of this quasar in 2005,2007. It has revealed a core-jet morphology. A high Doppler factor , is suggested for the jet, its nature is discussed in this report on the basis of the multi-frequency VLBA and RATAN data collected. Synchrotron self-absorption was confirmed to be dominating at low frequencies, the magnetic field strength of the dominating jet feature is estimated of an order of 0.1, mG (© 2009 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim) [source] The acute effects of different whole body vibration amplitudes on the endocrine system of young healthy men: a preliminary studyCLINICAL PHYSIOLOGY AND FUNCTIONAL IMAGING, Issue 6 2006Marco Cardinale Summary Whole body vibration (WBV) has been suggested as an alternative form of exercise producing adaptive responses similar to that of resistance training. Very limited information is available on the effects of different vibration parameters on anabolic hormones. In this study, we compared the acute effects of different WBV amplitudes on serum testosterone (T) and insulin growth factor-1 (IGF-1). Nine healthy young recreationally active adult males (age 22 ± 2 years, height 181 ± 6.3 cm, weight 77·4 ± 9·5 kg) voluntarily participated in this randomized controlled (cross-over design) study. The subjects performed 20 sets of 1 min each of WBV exercise in the following conditions: Non-vibration condition (control), low amplitude vibration [low (30 Hz, 1·5 mm peak-to-peak amplitude)] and high amplitude vibration [high (30 Hz, 3 mm peak-to-peak amplitude)]. Blood samples were collected before, after 10 sets, at the end (20th set) and after 24 h of the exercise bout. WBV exercise did not produce significant changes in serum T and IGF-1 either with low or high amplitude when compared with the control condition. The results of this study demonstrate that a single session of WBV exposure with a frequency of 30 Hz and amplitudes of 1·5 and 3 mm does not noticeably alter serum T and IGF-1 levels. [source] Two-photon Raman-type self-induced transparency forfew-cycle laser pulsesLASER PHYSICS LETTERS, Issue 3 2005I. P. Prokopovich Abstract We show the both amplitude and spectrum dynamics of few-cycle laser pulses in two-photon Raman-type self-induced transparency in Ar+ ions, that permit to generate half-cycle laser pulses (FWHM) with more high amplitudes and photon energy as well as spectral widths. (© 2005 by Astro, Ltd. Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) [source] Analysis of the effect of particle size distributions on the fluid dynamic behavior and segregation patterns of fluidized, vibrated and vibrofluidized bedsASIA-PACIFIC JOURNAL OF CHEMICAL ENGINEERING, Issue 1 2007Roger Valeri Daleffe Abstract In this work, the effects of particle size distribution on the dynamics and segregation patterns in fluidized, vibrated and vibrofluidized beds were investigated. Four particle size distributions composed of glass spheres were tested: binary, flat, Gaussian and a reference one, all of them with a mean Sauter diameter equal to 2.18 × 10,3 m. The experimental setup consisted basically of a circular glass chamber with a height of 0.50 m and diameter of 0.114 m and was operated in different modes: as a fluidized bed (, = 0), or either as vibrated or vibrofluidized beds (, = 2). The pressure drops in the fluidized and vibrofluidized beds were not significantly affected by the particle size distributions. Well-defined segregation patterns were observed in fluidized and vibrated beds, with the small particles concentrated at the top and the large particles at the bottom in the fluidized bed, and with a reversed pattern in the vibrated bed. Segregation patterns in the vibrofluidized bed depended on the values of the vibration parameters. Segregation in vibrofluidized and vibrated beds was minimized by operating at high amplitudes of vibration. Copyright © 2007 Curtin University of Technology and John Wiley & Sons, Ltd. [source] | |||||||||||||