RF and microwave power amplifiers and transmitters are used in a wide variety of applications including wireless communication, jamming, imaging, radar, and RF heating. This article provides an introduction and historical background for the subject, and begins the technical discussion with material on signals, linearity, efficiency, and RF-power devices. At the end, there is a convenient summar...

Objective(s):Osteoarthritis (OA) is globally one of the most common diseases from the middle age onwards. Cartilage is an avascular tissue therefore it cannot be repaired in the body. Conservative treatments have failed as a good remedy and cell therapy as a decisive cure is needed. One of the best and easily accessible cell sources for this purpose is adipose-derived stem cells which can be di...

Many current psychophysical models propose that visual processing in cortex is hierarchical, with nonlinearities sandwiched between linear stages of processing. In earlier publications, we proposed a model of this type to account for masking effects found with spatial frequency and orientation discriminations. Our model includes two nonlinear mechanisms that regulate contrast sensitivity in ear...

Observers can use spatial scale information flexibly depending on categorisation task and on their prior sensitisation. Here, we explore whether attentional modulation of spatial frequency processing at early stages of visual analysis may be responsible. In three experiments, we find that observers' perception of spatial frequency (SF) band-limited scene stimuli is determined by the SF content ...

Studies on functional hemispheric asymmetries have suggested that the right vs. left hemisphere should be predominantly involved in low vs. high spatial frequency (SF) analysis, respectively. By manipulating exposure duration of filtered natural scene images, we examined whether the temporal characteristics of SF analysis (i.e., the temporal precedence of low on high spatial frequencies) may in...

To determine the relationship between the spatial channels for luminance and shape-from-stereo-disparity processing we measured disparity modulation sensitivity as a function of disparity spatial frequency for sinusoidal modulations of a field of Gabor micropatterns of differing luminance spatial frequency. We first examine the effects of contrast, spatial bandwidth and element density and show...