[en] Since the tragic events of September 11, 2001, the international relations have become more complex and the arms control concept, born during the cold war and implemented during the 3 last decades is today marking time. Disarmament and non-proliferation, which were the keystones of arms control and international negotiations, are today undergoing erosion. This article analyzes the change of situation between the end of the 20. century and the beginning of the 21. century. Three steps are defined by the author: a 'flux' step with the signature of a huge number of international agreements about non-proliferation and arms control, a stagnation step marked by the difficulties of implementing some of the existing treaties and by the violation by some states of some of them, and a 'reflux' step marked by a freezing up of the bilateral US-Russian disarmament process and a general renouncement of the multilateral arms control concept. (J.S.)

[en] We study the phonon-assisted mechanism for nuclear spin relaxation (NSR) of magnetic impurity in two-dimensional electron gas system under quantum-Hall effect conditions. The nuclear spin impurity interacts mainly with discrete bound Landau state caused by resonance scattering with the impurity. The lattice distortion around the defect creates localized phonons which take part in the spin-flip transition. It is found that in the field dependence of the NSR rate T₁^-1 only the equidistant resonance transitions depending on the frequency of the localized phonon are allowed. This spectral structure may be used as a probe for studying the localized vibrational modes frequency and the electron-phonon coupling for various magnetic impurities. The obtained NSR rate, T₁^-1, oscillates periodically in the inverse magnetic field. Estimation for Fe impurity in GaAs quantum well is given

[en] Short communication

[en] The occurrence of new threats and the progress of proliferation of weapons of mass destruction raises several questions about the future of multilateral disarmament and the about all these treaties which have built up the architecture of the international security. This article analyzes the possibilities of preserving this heritage through the search of a better efficiency of existing means and the re-launching of the disarmament and non-proliferation enterprises thanks to the search for a relevance goal. (J.S.)