scholarly journals Attenuation of high-frequency (30–200 Hz) thalamocortical EEG rhythms as correlate of anaesthetic action: evidence from dexmedetomidine

2017 ◽  
Vol 119 (6) ◽  
pp. 1150-1160 ◽  
Author(s):  
G. Plourde ◽  
F. Arseneau
Keyword(s):  
High Frequency ◽  
Eeg Rhythms ◽  
Anaesthetic Action

scholarly journals Comparison of the EDA and EEG frequency components (qualitative analysis)

2017 ◽  
Vol 10 (2) ◽  
pp. 104-113 ◽  
Author(s):  
A.I. Nazarov
Keyword(s):  
Qualitative Analysis ◽  
Frequency Analysis ◽  
Galvanic Skin Response ◽  
High Frequency ◽  
Eeg Rhythms ◽  
Eeg Signals ◽  
Skin Potential ◽  
Skin Response ◽  
Frequency Components ◽  
Alpha Beta

The author recorded galvanic skin response (GSR, Feret method), skin potential (SP, Tarkhanov method) and local frontal encephalogram (Fp1). GSR was recorded with an amplifier bandwidth of 0.05-1 Hz, SP and EEG amplified with biopotential broadband amplifiers in the range 0.05-300 Hz. SP and local EEG signals were processed by the same algorithm. We obtained profiles of SP and EEG containing topologically similar low (LF) and high frequency (HF) components in the range of 0.05-45 Hz. LF-components of SP and EEG in some subjects were identical (in phase) of the GSR, in other subjects they were antiphased, in still others both types were observed. High-frequency components of SP contained rhythms, similar to EEG rhythms (Delta, Theta, Alpha, Beta, Gamma). However, frequency analysis showed that SP rhythms differ from local EEG rhythms in power and frequency distribution. The findings are discussed in the context of the nature of biorhythms.

Localised astroglial dysfunction disrupts high-frequency EEG rhythms

2004 ◽  
Vol 112 (2) ◽  
pp. 205-213 ◽  
Author(s):  
J. O. Willoughby ◽  
L. Mackenzie ◽  
K. J. Pope ◽  
M. Broberg ◽  
M. Nilsson
Keyword(s):  
High Frequency ◽  
Eeg Rhythms

scholarly journals MECHANISMS OF INTERACTION BETWEEN THE CIRCADIAN SYSTEM, EEG RHYTHMS AND REGULATION OF VEGETATIVE PROCESSES

2016 ◽  
Vol 1 (3) ◽  
pp. 51-55
Author(s):  
N P Romanhuk ◽  
N L Tyurin ◽  
O V Borisova ◽  
L N Loginova ◽  
L A Kirasirova
Keyword(s):  
Blood Pressure ◽  
Blue Light ◽  
High Frequency ◽  
Frequency Component ◽  
Circadian System ◽  
High Frequency Oscillation ◽  
Eeg Rhythms ◽  
Short Term Exposure ◽  
Beta 2 ◽  
Stimulation Of

Aim - to investigate the dynamics of EEG rhythms and vegetative responses in human on a short-term exposure of the retina to the blue light in the spectrum of maximum sensitivity of circadian photoreceptors during daytime wake. Materials and methods. EEG parameters (BP-010302 BrainАmp Standart128), blood pressure and heart rate variability (HRV) were recorded at 22 volunteer students aged 18-20 years before, after and during the 2-5 minute stimulation of circadian retinal receptors by blue light with maximum wavelength of 480 nm. Results. The stimulation of the photoreceptors of the circadian system correlates with the dynamics of the following neurovegetative processes: desynchronization in beta2- and gamma EEG rhythms, synchronization in teta2- and alpha1-frequency bands; increase in the duration of RR interval and power of low-frequency component of HRV, decrease in the percentage of high-frequency oscillation spectrum of HRV and decrease in systolic blood pressure. Termination of the stimulation of circadian system photoreceptors causes the transformation of EEG rhythms response with predominance of synchronization in low (teta1, teta 2), medium (alpha 1, alpha 2, alfa 3) and high frequency (beta 2) bands. Conclusion. The paper shows the possibility of quick correction of human vegetative background by controlling the circadian system. The human circadian clock is likely to control functional brain activity involving beta 2- and gamma-quantization.

The Microstructure of Steatite (Protoenstatite)

1985 ◽  
Vol 43 ◽  
pp. 236-237
Author(s):  
W. E. Lee ◽  
A. H. Heuer
Keyword(s):  
High Frequency ◽  
Glass Ceramics ◽  
Magnesium Silicate ◽  
Beam Current ◽  
Glassy Matrix ◽  
Angle Of Incidence ◽  
X Ray ◽  
Mechanical And Electrical Properties ◽  
Argon Ions ◽  
High Temperature Polymorph

IntroductionTraditional steatite ceramics, made by firing (vitrifying) hydrous magnesium silicate, have long been used as insulators for high frequency applications due to their excellent mechanical and electrical properties. Early x-ray and optical analysis of steatites showed that they were composed largely of protoenstatite (MgSiO3) in a glassy matrix. Recent studies of enstatite-containing glass ceramics have revived interest in the polymorphism of enstatite. Three polymorphs exist, two with orthorhombic and one with monoclinic symmetry (ortho, proto and clino enstatite, respectively). Steatite ceramics are of particular interest a they contain the normally unstable high-temperature polymorph, protoenstatite.Experimental3mm diameter discs cut from steatite rods (∼10” long and 0.5” dia.) were ground, polished, dimpled, and ion-thinned to electron transparency using 6KV Argon ions at a beam current of 1 x 10-3 A and a 12° angle of incidence. The discs were coated with carbon prior to TEM examination to minimize charging effects.

Simulations of high-resolution images of amorphous silicon films

1986 ◽  
Vol 44 ◽  
pp. 544-545
Author(s):  
G. Y. Fan ◽  
J. M. Cowley
Keyword(s):  
Electron Microscope ◽  
High Frequency ◽  
Fourier Transformation ◽  
Amorphous Materials ◽  
Low Frequency ◽  
Chromatic Aberration ◽  
Structure Information ◽  
Frequency Components ◽  
High Resolution Images ◽  
Spatial Frequency Spectrum

It is well known that the structure information on the specimen is not always faithfully transferred through the electron microscope. Firstly, the spatial frequency spectrum is modulated by the transfer function (TF) at the focal plane. Secondly, the spectrum suffers high frequency cut-off by the aperture (or effectively damping terms such as chromatic aberration). While these do not have essential effect on imaging crystal periodicity as long as the low order Bragg spots are inside the aperture, although the contrast may be reversed, they may change the appearance of images of amorphous materials completely. Because the spectrum of amorphous materials is continuous, modulation of it emphasizes some components while weakening others. Especially the cut-off of high frequency components, which contribute to amorphous image just as strongly as low frequency components can have a fundamental effect. This can be illustrated through computer simulation. Imaging of a whitenoise object with an electron microscope without TF limitation gives Fig. 1a, which is obtained by Fourier transformation of a constant amplitude combined with random phases generated by computer.

SEM image sharpness analysis

1996 ◽  
Vol 54 ◽  
pp. 142-143
Author(s):  
M. T. Postek ◽  
A. E. Vladar
Keyword(s):  
High Frequency ◽  
Low Frequency ◽  
Quantitative Information ◽  
Primary Electron ◽  
Image Sharpness ◽  
Critical Dimensions ◽  
Sem Image ◽  
Frequency Changes ◽  
Electron Microscopes ◽  
Scanning Electron

Fully automated or semi-automated scanning electron microscopes (SEM) are now commonly used in semiconductor production and other forms of manufacturing. The industry requires that an automated instrument must be routinely capable of 5 nm resolution (or better) at 1.0 kV accelerating voltage for the measurement of nominal 0.25-0.35 micrometer semiconductor critical dimensions. Testing and proving that the instrument is performing at this level on a day-by-day basis is an industry need and concern which has been the object of a study at NIST and the fundamentals and results are discussed in this paper.In scanning electron microscopy, two of the most important instrument parameters are the size and shape of the primary electron beam and any image taken in a scanning electron microscope is the result of the sample and electron probe interaction. The low frequency changes in the video signal, collected from the sample, contains information about the larger features and the high frequency changes carry information of finer details. The sharper the image, the larger the number of high frequency components making up that image. Fast Fourier Transform (FFT) analysis of an SEM image can be employed to provide qualitiative and ultimately quantitative information regarding the SEM image quality.

Real Ear Sound Pressure Levels Developed by Three Portable Stereo System Earphones

1992 ◽  
Vol 1 (4) ◽  
pp. 52-55 ◽  
Author(s):  
Gail L. MacLean ◽  
Andrew Stuart ◽  
Robert Stenstrom
Keyword(s):  
High Frequency ◽  
Sound Pressure ◽  
Low Frequency ◽  
Test System ◽  
Output Frequency ◽  
Frequency Effects ◽  
Adult Men ◽  
Frequency Responses ◽  
Significant Difference ◽  
Sound Pressure Levels

Differences in real ear sound pressure levels (SPLs) with three portable stereo system (PSS) earphones (supraaural [Sony Model MDR-44], semiaural [Sony Model MDR-A15L], and insert [Sony Model MDR-E225]) were investigated. Twelve adult men served as subjects. Frequency response, high frequency average (HFA) output, peak output, peak output frequency, and overall RMS output for each PSS earphone were obtained with a probe tube microphone system (Fonix 6500 Hearing Aid Test System). Results indicated a significant difference in mean RMS outputs with nonsignificant differences in mean HFA outputs, peak outputs, and peak output frequencies among PSS earphones. Differences in mean overall RMS outputs were attributed to differences in low-frequency effects that were observed among the frequency responses of the three PSS earphones. It is suggested that one cannot assume equivalent real ear SPLs, with equivalent inputs, among different styles of PSS earphones.

Sign in / Sign up

Export Citation Format

Share Document