Summarizing the results of the last section, inflation predicts not only a flat, smooth universe, but also provides a natural mechanism for the production of primordial density and gravitational wave fluctuations.
power-law spectrum A spectrum quantified in terms of a power law.
The scalar, or density fluctuation amplitude when a mode crosses the horizon is given by
... power spectrum function of power signal, V 2 /rad s −1.
The primordial power spectrum. The characterization of flow regimes with power spectral density distributions of pressure fluctuations during condensation in smooth and micro-fin tubes. The amplitude of the PSD is normalized by the spectral resolution employed to digitize the signal. The Power Spectral Density (PSD) comes into play when dealing with stochastic signals, or signals that are generated by a common underlying process, but may be different each time the signal is measured.
Here we quantify the constraints that the detection of distant GRBs would place on structure formation models with reduced small-scale power. A PSD is typically used to characterize broadband random signals. For vibration data, a PSD has amplitude units of g2/Hz. It's a long computation and, to be honest, I never had the courage to read through it but after a quick look it seems to present all the necessary steps to establish the link between the temperature and the density/potential fluctuations, and also deals with the power spectrum of the temperature anisotropy.
A Power Spectral Density (PSD) is the measure of signal's power content versus frequency. The recent experiment of Celasco and co-workers represents a new, powerful approach to this problem, via the measurement of the power spectrum of the voltage noise generated by resistivity fluctuations.
The latter originate in vacancy number fluctuations. An expression is derived which relates the mean curvature of isodensity surfaces to the power spectrum of density fluctuations in the linear regime of Gaussian fluctuations with random phases. Given just one "realization" of a stochastic process--a stochastic signal--you can only estimate what the underlying Power Spectral Density is.
Cosmological models that include suppression of the power spectrum of density fluctuations on small scales exhibit an exponential reduction of high-redshift, nonlinear structures, including a reduction in the rate of gamma-ray bursts (GRBs). The power spectrum of velocity fluctuations from the galaxy distribution in the Stromlo-APM redshift survey is consistent with the observed rms cluster velocity and with the observed large-scale bulk flow when the parameter $\beta$ is in the range 0.4-0.5. The measurement in thermal equilibrium of the vacancy contribution to the residual resistivity of metals has posed certain difficulties.