This study examined the contributions of passive and active membrane properties to the temporal selectivities of electrosensory neurons in vivo. The intracellular responses to time-varying (2-30 Hz) electrosensory stimulation and current injection of 27 neurons in the midbrain of the weakly electric fish Eigenmannia were recorded. Each neuron was filled with biocytin to reveal its anatomy. Neur...

Steven Lehar [email protected] Fourier theory is pretty complicated mathematically. But there are some beautifully simple holistic concepts behind Fourier theory which are relatively easy to explain intuitively. There are other sites on the web that can give you the mathematical formulation of the Fourier transform. I will present only the basic intuitive insights here, as applied to spatial im...

For time-invariant degradation models and stationary signals and noise, the classical Fourier domain Wiener filter, which can be implemented in O(N logN) time, gives the minimum mean-square-error estimate of the original undistorted signal. For time-varying degradations and nonstationary processes, however, the optimal linear estimate requires O(N2) time for implementation. We consider filterin...

In the Wigner domain of a one-dimensional function, a certain chirp term represents a rotated line delta function. On the other hand, a fractional Fourier transform (FRT) can be associated with a rotation of the Wigner-distribution function by an angle connected with the FRT order. Thus with the FRT tool a chirp and a delta function can be transformed one into the other. Taking the chirp as add...

It is critical for the safety monitoring of highway bridges that beam bridge damage can be identified from dynamic response passing vehicles. Numerical simulations vehicles were conducted utilizing vehicle–bridge coupling vibration theory and indirect measurement method. Fast Fourier transform was performed on time history vehicle acceleration, driving frequency component its instantaneous ampl...

We model the radial segregation patterns that form in a thin rotating drum partially filled with beads of two sizes. We predict that the waviness (or amplitude-to-wavelength ratio, denoted w) of a pattern should be subjected to low-pass filtering with a cutoff waviness w(c) that depends strongly on the fill level of the drum. Then we perform experiments and find that w</=w(c) for all patterns, ...

In the subject paper @Alku and Vilkman, J. Acoust. Soc. Am. 98, 763–767 ~1995!; hence AV#, AV describe the results of their research on the effect of bandwidth on estimated voice source parameters. They found that reducing the bandwidth ~by low-pass filtering the glottal flow signals! leads to a distortion of the estimated parameters. Although I do agree that low-pass filtering influences the e...

This paper relates to correcting colours in digital photography. Three low pass filters are used to prevent noise amplification during colour correction. It is well known that a straightforward application of a low pass filter reduces the sharpness of an image. In this paper, the filtering is applied in a non-conventional way which naturally compensates the blur introduced by the filtering. Thi...

In the subject paper (Alku and Vilkman, 1995; hence AV), AV describe the results of their research on the effect of bandwidth on estimated voice source parameters. They found that reducing the bandwidth (by low-pass filtering the glottal flow signals) leads to a distortion of the estimated parameters. Although I do agree that low-pass filtering influences the estimates of the voice source param...

Most search engines return a lot of unwanted information. A more thorough filtering process can be performed on this information to sort out the relevant documents. A new method called Frequency Domain Scoring (FDS), which is based on the Fourier Transform is proposed. FDS performs the filtering by examining the locality of the keywords throughout the documents. This is examined and compared to...