White noise stimulation

In recent years, several technologies such as white noise stimulation, hydrodynamic focusing and trapping arrays have been implemented within single cell impedance microfluidic cytometry to achieve broadband spectroscopy, improvement in sensitivity and continuous time course measurements. 

The results of these two studies and others provide further support for the theoretical inverted U-shaped arousal function. In the first case,93 high doses of caffeine pushed subjects over the top of the curve and hence impaired vigilance performance. As time passed and the subject became more accustomed to the experimental situation, arousal returned to more optimal levels and performance improved. In the second study,94 caffeine combined with moderately high intensity situational stimulation (white noise) to drive arousal up beyond the point of transmarginal inhibition and, again, decrease performance. 

The inconsistent effects of caffeine in cognitively mediated performance tasks may result from differences in age groups, dosage levels, and environmental factors.124-125 The latter have been shown to substantially affect arousal126-127 in both adults128-129 and children.130-131 Office noise is effective in increasing self-reported arousal,132 as are white noise in the laboratory,94 exercise,133 and stress.134 Such environmental factors are sources of arousal and can interact with stimulants like caffeine.135... 

Threshold to detect passive motion (TTDPM) is used to evaluate kinesthesia [32, 37, 38], In TTDPM, a subject is blindfolded to eliminate visual cues and has headphones with white noise to eliminate auditory cues. When a subject s knee is passively and slowly moved over a 5-30-s period either into extension or flexion using a motor controlled device, the subject is required to respond as soon as he or she detects the motion and to inform the examiner with an on-off switch. The TTDPM, tested at slow angular velocity (0.5-2.5°/s), is considered to be the maximum to stimulate joint receptors and the minimum to stimulate muscle receptors [39]. 

The main criticism of predictive analysis is that the original stimulation signal is rarely known. In practice, the algorithm predicts that the stimulation is either a pitched pulse train or white noise. In other words, the outcome of the all-zero filter is compared to an artificial stimulation that is rather rudimentary, thus limiting the efficiency of technique to specific types of sounds e.g. prediction analysis works satisfactorily for speech and some wind sounds. 

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