The two main perturbative schemes for the non-linear evolution of large-scale structures are the Lagrangian and the Eulerian ones. The former has been set as a much more powerful technique, due to its property of yielding the exact solution in the plane-symmetric case. We have applied the Eulerian scheme to this plane symmetric case and have

Phase and gain relations between low-degree acoustic modes measured as intensity and velocity fluctuations have been carried out using various instruments and techniques. The helioseismic instrument aboard the Solar and Heliospheric Observatory (SOHO) satellite provides an opportunity to observe solar oscillations in intensity and velocity under

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Detailed photographic mappings are presented for 33 early-type E and S0 galaxies in the Virgo cluster which are brighter than 14 mag. The mappings are based on B-band CCD and large-field photographic material. Attention is given to the geometrical characteristics of the isophotes in order to establish whether a faint disk is present, and the

AX J1745.6-2901 is a low-mass X-ray binary with an accreting neutron star, showing clear evidence for highly ionized absorption. Strong ionized Fe Kα and Kβ absorption lines are always observed during the soft state, whereas they disappear during the hard state. We computed photoionization stability curves for the hard and the soft states, under