Table of contents

In this work we consider an inverse problem of finding an unknown time-dependent parameter in one-dimensional parabolic equations. This problem appears widely in modeling of several phenomena in physics and engineering. Adomian decomposition method is applied for finding the solution of this problem. The decomposition procedure of Adomian is a powerful tool for solving various kinds of linear and nonlinear problems. To show the efficiency of the technique, we will present the results of applying this method to two problems from the literature and compare it with some well known finite difference schemes.

In this Paper, we analyse the singularity structure aspects of the (2 + 1) dimensional generalized Sasa-Satsuma (GSS) equation and confirm its integrability. Using the results of the Painlevé analysis, we unearth a new class of localized coherent structures of the (2 + 1) dimensional GSS equation and study their interactions. The new class of solutions includes multiple conoidal periodic waves driven by doubly periodic Jacobian elliptic functions and multiple dromions. We have also explored the concept of fission and fusion of dromions in detail.

We determine the response of bowed structural elements to a two-frequency, transverse load. The effects of both initial curvature (i.e., quadratic nonlinearities) and mid-surface stretching (i.e., cubic nonlinearities) are included. We investigate possible large-amplitude-low-frequency responses to excitations of such structural elements (drumming) and determine the conditions under which the one-half subharmonics of the transverse load can be excited individually in the presence of three-to-one internal resonance. The method of multiple time scales is used to determine four first-order nonlinear ordinary differential equations that govern the time variation of the amplitudes and phases of the interacting modes. The fixed points of these equations are obtained and their stability is determined. Numerical solutions are carried out and graphical representations of the results are presented. The region of multivalued disappear for increasing the parameters µ₂₂, d₆, Γ₂ and decreasing the parameters d₂, d₄, d₅ and ω₁. The nontrivial solution has unstable solution for increasing the damping factors. The trivial solution has unstable and stable solutions for decreasing the parameters Γ₁ and Γ₂ respectively.

Spontaneous development of shock-like singularities in axisymmetric solutions of the Hall-MHD equations is discussed. It is shown that the Hall-term in Ohm's law leads to a Burgers-type equation for the magnetic field evolution in weakly compressible regime. Numerical simulations are used to investigate the validity of this approximation for a particular class of initial conditions.

We have studied the pyroelectric properties of a ferroelectric superlattice described by the Ising model in a transverse field using effective field theory with a probability distribution technique that accounts for the self-spin correlation functions.

The Curie temperature, dielectric constant, and polarization have been obtained. The most striking feature is that the dielectric constant presents two pyroelectric peaks for large-period superlattices. The pyroelectric peak at low temperature disappears when the period is small enough.

We discuss a specific quasifree mechanism (QFM) of the ionization processes, which requires only small momentum transfer to the nucleus. The QFM mechanism is important in the kinematical regions where the two-electron system can absorb a photon without participation of the nucleus. The QFM leads to the complicated shape of the double photoionization spectrum curve, providing the breakdown of the nonrelativistic high energy asymptotic of the double-to single photoionization ratio. Calculation of the QFM contribution requires a consistent theoretical approach. Use of oversimplified approximations leads to misleading results. In certain kinematical regions the QFM provides the leading contribution, and thus the results obtained without inclusion of QFM are erroneous. Experimental detection of QFM is a complicated, but interesting problem.

We summarize recent experimental and theoretical advances in the physics of coherent multiple light scattering in ultracold atomic gases. Current outstanding problems are reviewed, along with prospects for significant new insights into mesoscopic physics in ultracold atomic samples. The possibility of experimental demonstration of strong localization of light in atomic gases is discussed.

The 12th International Conference on the Physics of Highly Charged Ions was held in Vilnius (Lithuania) 6–11 September 2004. The papers presented at this conference are analysed and commented upon. The following thematic topics were discussed at the conference: fundamental aspects of the physics of multiply charged atoms, structure and spectroscopy, interactions with photons, plasmas and related processes in strong fields, collisions with electrons, ions, atoms and molecules, interaction with clusters, surfaces and solids, production of highly charged ions, experimental developments and applications. The trends in the development of this field of physics are discussed as well.

Atomic physics can probe the Lorentz and CPT symmetries at the Planck level. Bounds on coefficients for Lorentz violation have been found using atomic clocks, masers, electromagnetic cavities, and Penning traps, among others, and in future it may be possible to place bounds using spectroscopy of antihydrogen atoms. The CPT '04 Meeting on CPT and Lorentz Symmetry was held in August 2004 in Bloomington, Indiana, USA, and covered Lorentz violation in all branches of physics. This report gives an overview of the recent advances in Lorentz-symmetry studies in atomic and optical physics.

Argon is one of the gases best investigated and most widely used in plasma discharge devices for a multitude of applications that range from wavelength reference standards to controlled fusion experiments. Reviewing atomic physics and spectroscopic problems in various ionization stages of Ar, the past use and future options of employing an electron beam ion trap (EBIT) for better and more complete Ar data in the x-ray, EUV and visible spectral ranges are discussed.

Current antiproton physics as carried out at the Antiproton Decelerator (AD) of CERN is focussed on precision spectroscopy of antiprotonic atoms and antihydrogen for tests of CPT symmetry and QED. For efficient stopping of antiprotons, the energy of the AD is however still too high. A new facility called FLAIR (Facility for Low-energy Antiproton and Ion Research) has recently been proposed that includes cooled beams of antiprotons at energies below 100 keV. This will allow for a much higher rate of trapped antiprotons and therefore greatly advance the currently performed experiments. Furthermore, the availability of continuous beams will make many new experiments possible.

During a number of years, the production of Physica Scripta has been taken care of by Lindsay Ross International Ltd (now part of Marston Books Ltd). The editorial office of Physica Scripta has worked in close collaboration with the production company and many routines have been developed in joint efforts. The present issue of Physica Scripta is the last produced by LRI/Marston and I would like to take this opportunity to thank all our collaborators at the production company for their contributions to the success of our journal during this extended period of cooperation.

For the next issue, i.e. the January 2006 issue, the production has been moved to IOP Press but the transition should be seamless to our contributors.