in this study, absorption of high frequency radio waves in the ionospheric plasma have beeninvestigated. the wave equation was obtained in terms of ionospheric parameters. the numerical values ofthe absorption have been calculated for 4 mhz, 4.5 mhz and 5 mhz waves. the necessary parameters forcalculation have been obtained using an international reference ionosphere (iri) model. the altitudina...

Sources of high frequency gravitational waves are reviewed. Gravitational collapse, rotational instabilities and oscillations of the remnant compact objects are potentially important sources of gravitational waves. Significant and unique information for the various stages of the collapse, the evolution of protoneutron stars and the details of the equations of state of such objects can be drawn ...

A laser ultrasonic system that allows for the excitation and detection of high frequency (GHz range) acoustic waves using low frequency, low cost detection electronics is presented. A continuous wave diode laser source, operating at a wavelength of 1544nm, is amplitude modulated using an integrated electro-absorption modulator and used to excite high frequency, narrow bandwidth acoustic waves. ...

Objectives: Autism Spectrum Disorder (ASD) is a group of neurodevelopment syndromes with impairments in social communications and restrictive or repetitive behaviors. Neurofeedback is a new method that may regulate neuro and metabolic function in brain. This study is semi-experimental, with pre and post test.  Methods: In 26 children with ASD, 40 sessions of Neurofeedback were done. Brain...

In this work a continuum model for high frequency poroelastic longitudinal waves in hydrogels is presented. A viscoelastic force describing the interaction between the polymer network and the bounded water present in such materials is introduced. The model is tested by means of ultrasound wave speed and attenuation measurements in polyvinylalcohol hydrogel samples. The theory and experiments sh...

the purpose of this research is to analyze heat waves characteristics in the warm period of the year as a climatic hazard in iran. in this study, the daily maximum temperature is taken at 44 synoptic stations during the period 1981-2010. these temperature values were used to extract the intensity, frequency and duration of heat waves using percentile thresholds of 90, 95, and 98. the results sh...