Visualizing characteristics of ocean data collected during the Shuttle Imaging Radar-B experiment

Topographic measurements of sea surface elevation collected by the Surface Contour Radar (SCR) during NASA's Shuttle Imaging Radar (SIR-B) experiment are plotted as three dimensional surface plots to observe wave height variance along the track of a P-3 aircraft. Ocean wave spectra were computed from rotating altimeter measurements acquired by the Radar Ocean Wave Spectrometer (ROWS). Fourier power spectra computed from SIR-B synthetic aperture radar (SAR) images of the ocean are compared to ROWS surface wave spectra. Fourier inversion of SAR spectra, after subtraction of spectral noise and modeling of wave height modulation, yields topography similar to direct measurements made by SCR. Visual perspectives on the SCR and SAR ocean data are compared. Threshold distinctions between surface elevation and texture modulations of SAR data are considered within the context of a dynamic statistical model of rough surface scattering. The result of these endeavors is insight as to the physical mechanism governing the imaging of ocean waves with SAR

Digital Restoration of Ancient Papyri

Image processing can be used for digital restoration of ancient papyri, that is, for a restoration performed on their digital images. The digital manipulation allows reducing the background signals and enhancing the readability of texts. In the case of very old and damaged documents, this is fundamental for identification of the patterns of letters. Some examples of restoration, obtained with an image processing which uses edges detection and Fourier filtering, are shown. One of them concerns 7Q5 fragment of the Dead Sea Scrolls

Using Cluster Abundances and Peculiar Velocities to Test the Gaussianity of the Cosmological Density Field

(Abridged) By comparing the frequency of typical events with that of unusual events, one can test whether the cosmological density distribution function is consistent with the normally made assumption of Gaussianity. To this end, we compare the consistency of the tail-inferred (from clusters) and measured values (from large-scale flows) of the rms level of mass fluctuations for two distribution functions: a Gaussian, and a texture (positively-skewed) PDF. Averaging the recent large-scale flow measurements, we find that observations of the rms and the tail at the 10 h^-1 Mpc scale disfavor a texture PDF at ~1.5 sigma in all cases. However, taking only the most recent measurement of the rms, that from Willick et al. (1997b), the comparison disfavors textures for low Omega_0=0.3, and disfavors Gaussian models if Omega_0=1 (again at ~1.5 sigma). Predictions for evolution of high temperature clusters can also be made for the models considered, and strongly disfavor Omega_0=1 in Gaussian models and marginally disfavor Omega_0=1 in texture models. Only Omega_0=0.3 Gaussian models are consistent with all the data considered.Comment: 34 pg incl. 8 embedded figures, LaTeX, aaspp4.sty, submitted to Ap