scholarly journals Cross-field transport due to low-frequency oscillations in the auroral region: A three-dimensional simulation

1999 ◽  
Vol 104 (A3) ◽  
pp. 4297-4304 ◽  
Author(s):  
Supriya B. Ganguli ◽  
Parvez N. Guzdar ◽  
Valeriy V. Gavrishchaka ◽  
Warren A. Krueger ◽  
Paul E. Blanchard
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Auroral Region ◽  
Low Frequency Oscillations ◽  
Dimensional Simulation

Experimental and biological variation of three-dimensional transcranial Doppler measurements

1993 ◽  
Vol 75 (6) ◽  
pp. 2805-2810 ◽  
Author(s):  
L. L. Thomsen ◽  
H. K. Iversen
Keyword(s):  
Middle Cerebral Artery ◽  
Cerebral Artery ◽  
Transcranial Doppler ◽  
Coefficient Of Variation ◽  
Cerebral Arteries ◽  
Three Dimensional ◽  
Low Frequency ◽  
Control Groups ◽  
Mean Velocity ◽  
Low Frequency Oscillations

A new transcranial Doppler system (3-D Transscan, Eden Medizinische Elektronik) was evaluated in relation to sex, age, intersubject, interobserver, side-to-side, and day-to-day variation. Fifty-eight healthy volunteers participated (aged 18–80 yr). Mean velocity was higher in females than in males and decreased with age. The coefficient of variation in the middle cerebral artery was 26% between subjects, 20% between sides, 16% between days, 13% between observers, and 7% during 5 min. The coefficient of variation was higher in the anterior and posterior cerebral arteries. Bruits were heard in 35 subjects, 24 females and 11 males (P = 0.002). When middle cerebral artery velocity was monitored, high- and low-frequency oscillations were found, with a mean frequency of 5 and 1.6/min, respectively. These variations underline the necessity of standardized conditions and very carefully matched control groups in studies using transcranial Doppler. This is especially important when expected changes are small and easy to overlook, as in studies of normal physiological responses and migraine.

scholarly journals Occurrence of Calcium Oscillations in Human Spermatozoa Is Based on Spatial Signaling Enzymes Distribution

2021 ◽  
Vol 22 (15) ◽  
pp. 8018
Author(s):  
Julia Korobkin ◽  
Fedor A. Balabin ◽  
Sergey A. Yakovenko ◽  
Ekaterina Yu. Simonenko ◽  
Anastasia N. Sveshnikova
Keyword(s):  
Calcium Signaling ◽  
Computational Models ◽  
Fluorescent Microscopy ◽  
Three Dimensional ◽  
Low Frequency ◽  
Calcium Oscillations ◽  
Qualitative Description ◽  
Human Spermatozoa ◽  
Three Dimensional Model ◽  
Low Frequency Oscillations

In human spermatozoa, calcium dynamics control most of fertilization events. Progesterone, present in the female reproductive system, can trigger several types of calcium responses, such as low-frequency oscillations. Here we aimed to identify the mechanisms of progesterone-induced calcium signaling in human spermatozoa. Progesterone-induced activation of fluorophore-loaded spermatozoa was studied by fluorescent microscopy. Two computational models were developed to describe the spermatozoa calcium responses: a homogeneous one based on a system of ordinary differential equations and a three-dimensional one with added space dimensions and diffusion for the cytosolic species. In response to progesterone, three types of calcium responses were observed in human spermatozoa: a single transient rise of calcium concentration in cytosol, a steady elevation, or low-frequency oscillations. The homogenous model provided qualitative description of the oscillatory and the single spike responses, while the three-dimensional model captured the calcium peak shape and the frequency of calcium oscillations. The model analysis demonstrated that an increase in the calcium diffusion coefficient resulted in the disappearance of the calcium oscillations. Additionally, in silico analysis suggested that the spatial distribution of calcium signaling enzymes governs the appearance of calcium oscillations in progesterone-activated human spermatozoa.

scholarly journals Recovering the Damping Rates of Cyclotron Damped Plasma Waves from Simulation Data

2017 ◽  
Vol 21 (4) ◽  
pp. 947-980 ◽  
Author(s):  
Cedric Schreiner ◽  
Patrick Kilian ◽  
Felix Spanier
Keyword(s):  
Three Dimensional ◽  
Low Frequency ◽  
Plasma Waves ◽  
Simulation Data ◽  
Simple Method ◽  
Particle In Cell ◽  
Frequency Plasma ◽  
Damping Rate ◽  
Theoretical Predictions ◽  
Dimensional Simulation

AbstractPlasma waves with frequencies close to the particular gyrofrequencies of the charged particles in the plasma lose energy due to cyclotron damping. We briefly discuss the gyro-resonance of low frequency plasma waves and ions particularly with regard to particle-in-cell (PiC) simulations. A setup is outlined which uses artificially excited waves in the damped regime of the wave mode's dispersion relation to track the damping of the wave's electromagnetic fields. Extracting the damping rate directly fromthe field data in real or Fourier space is an intricate and non-trivial task. We therefore present a simple method of obtaining the damping rate Γ from the simulation data. This method is described in detail, focusing on a step-by-step explanation of the course of actions. In a first application to a test simulation we find that the damping rates obtained from this simulation generally are in good agreement with theoretical predictions. We then compare the results of one-, two- and three-dimensional simulation setups and simulations with different physical parameter sets.

Three-Dimensional Simulation of Planar Solid Oxide Fuel Cell Stack

2008 ◽  
Vol 128 (2) ◽  
pp. 459-466 ◽  
Author(s):  
Yoshitaka Inui ◽  
Tadashi Tanaka ◽  
Tomoyoshi Kanno
Keyword(s):  
Fuel Cell ◽  
Solid Oxide Fuel Cell ◽  
Three Dimensional ◽  
Solid Oxide ◽  
Oxide Fuel ◽  
Fuel Cell Stack ◽  
Dimensional Simulation

THREE-DIMENSIONAL SIMULATION OF EFFERVESCENT ATOMIZATION SPRAY

2009 ◽  
Vol 19 (1) ◽  
pp. 75-90 ◽  
Author(s):  
Hong-Bing Xiong ◽  
Jian-Zhong Lin ◽  
Ze-Fei Zhu
Keyword(s):  
Three Dimensional ◽  
Atomization Spray ◽  
Dimensional Simulation
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