Spectral factorization plays an important role in many applications such as Wiener filter design, prediction, and estimation. It is known that spectral factorization is a non-continuous mapping on the space of all non-negative continuous functions, satisfying the Paley-Wiener condition. Additionally, it will be shown in this paper that every continuous spectrum is a discontinuity point of the s...

In this paper, a common problem in diphone synthesis is discussed, viz., the occurrence of audible discontinuities at diphone boundaries. Informal observations show that spectral mismatch is most likely the cause of this phenomenon. We first set out to find an objective spectral measure for discontinuity. To this end, several spectral distance measures are related to the results of a listening ...

By renormalization-group methods we obtain nonperturbative results about a d51 system of interacting spinless fermions in a periodic potential when the conduction band is filled. Both the strength of the interaction and the amplitude of the periodic potential are assumed to be small. We determine that the large-distance asymptotic behavior of the two-point Schwinger function is anomalous and de...

The theory of vibrational excitation transfer, which causes spectral diffusion and is also influenced by structural spectral diffusion, is developed and applied to systems consisting of vibrational chromophores. Excitation transfer induced spectral diffusion is the time-dependent change in vibrational frequency induced by an excitation on an initially excited molecule jumping to other molecules...

In order to constrain the nebular density distribution and velocity field, we model nebular lines profiles obtained at very high spectral resolution. The method and computer code applied to 2–3 nebular lines were described in earlier publications. In the present work we analyse 4–11 spectral lines observed simultaneously with the spectrometer ELODIE (R=42 000) for 8 planetary nebulae. For five ...

For the first time we demonstrate a multiwavelength, ultrabroadband, continuous-wave, tunable, polycrystalline Cr2+:ZnSe spatially-dispersive laser, operating in the near IR spectral region. We show a dual-wavelength operation of the laser, tunable over a 600 nm spectral range (2200-2800 nm), an ultrabroadband operation of the laser, producing a continuous 135 nm wide spectrum centered at 2500 ...