In this article, we present a mathematical theory of the Walker circulation of the large-scale atmosphere over the tropics. This study leads to a new metastable state oscillation theory for the El Niño Southern Oscillation (ENSO), a typical inter-annual climate low frequency oscillation. The mathematical analysis is based on 1) the dynamic transition theory, 2) the geometric theory of incompres...

There is growing recognition that neural oscillations are important in a wide range of perceptual and cognitive functions. One of the key issues in electrophysiological studies of schizophrenia is whether high or low frequency oscillations, or both, are related to schizophrenia because many brain functions are modulated with frequency specificities. Many recent electrophysiological studies of s...

Carbon, water and energy exchanges between forests and the atmosphere depend upon seasonal dynamics of both temperature and precipitation, which are influenced by low frequency climate oscillations such as: El Niño-Southern Oscillation (ENSO), North Atlantic Oscillation (NAO), Arctic Oscillation (AO), Eastern Pacific Oscillation (EPO) and the Pacific-North American (PNA). This study investigate...

An experimental study is presented on the spatial structure of the internal wave field emitted by a horizontally oscillating sphere in a uniformly stratified fluid. The limits of linear theory and the nonlinear features of the waves are considered as functions of oscillation amplitude. Fourier decomposition is applied to separate first harmonic waves at the fundamental frequency and higher harm...

A new voltage mode quadrature oscillator (VMQO) employing single Voltage differencing transconductance amplifier (VDTA), two grounded capacitors and one grounded resistor has been proposed. The proposed circuit enjoys following advantageous features: i) use of all grounded passive elements, ii) availability of electronic tuning, iii) independent control of frequency of oscillation (FO) and cond...

An innovative laser-vision-based sensing method is proposed to measure weld pool oscillation frequency in pulsed gas tungsten arc welding (GTAW-P). A low-power five-line laser pattern is projected onto the entire weld pool surface as well as its reflection is intercepted by an imaging plane and captured by a high-speed camera. By observing and analyzing the change of the captured laser images d...

Humans and most animals are able to navigate in their environment, which generates sensorial information of various kinds, such as proprioceptive cues and optic flow. Previous research focusing on the visual effects of walking (bob, sway, and lunge head motion) has shown that the perception of forward self-motion experienced by static observers can be modulated by adding simulated viewpoint osc...

This study describes the design of a multiphase sinusoidal oscillator (MSO) based on log-domain filtering concept. The circuit is a direct realisation of a first-order differential equation for obtaining the inverting and non-inverting low-pass filters. Each low-pass filter comprises only a grounded capacitor and four transistors. The proposed MSO can be instantaneously controlled over a very w...

extremely low frequency (elf) and radio frequency (rf) electromagnetic field may affect biological systems by raising generation free radicals by decline activities of glutathione peroxidase dismutase or increase in the lifetime of free radicals with inhibited pretreatment of cells antioxidant like that alpha tocopherol. elf and  rf electromagnetic  field maycan damaged dna  with raising level ...

Grasshoppers of 20 acridid species were examined using spectral analysis, laser vibrometry and electrophysiology to determine whether the song spectra, the best frequencies of tympanal-membrane vibrations and the threshold curves of the tympanal nerves are adapted to one another. The songs of almost all species have a relatively broad-band maximum in the region between 20 and 40 kHz and a narro...