Dynamical Processes on Complex Networks,by A. Barrat,M. Barthélemy and A. Vespignani

The present state of theory and experiment on the gravity-induced electric field in metallic conductors and the electric field in accelerated metal conductors is reviewed. The relevant equations are derived in very simple approximations. The results depend on whether the deformation of the lattice of positive ions is neglected or is taken into account. Experimental results obtained with freely falling electrons in a cavity in the metal do not agree with the measurements of potentials on rapidly spinning metal rotors. Older direct measurements of the specific charge of carriers in metallic conductors are also mentioned.     

Symmetry and Condensed Matter Physics – A Computational Approach,by M. El-Batanouny and F. Wooten

The behaviour of positrons below the inelastic collision threshold in rare gases can usually be completely accounted for in terms of the annihilation and elastic scattering cross sections for collisions between a positron and a single gas atom. Determining these cross sections has been the subject of many theoretical and experimental investigations. However the basic premise that the positron interacts with the gas atoms, one at a time, has been recently questioned by the yet unexplained results of some low-temperature experiments. This article discusses the annihilation and elastic scattering cross sections as they relate to the conventional picture of positrons in He, Ne, Ar, Kr and Xe gas; as well as the possibility of bound states for positrons in the gases at low temperatures.     

Comment on ‘Cr LVV Auger emission and photoreduction of hexavalent Cr oxides by A.G. Schrott,G.S. Frankel,A.J. Davenport,H.S. Isaacs,C.V. Jahnes and M.A. Russak’

A paper by Schrott et al. [Surf. Sci. 250 (1991) 139] on the Auger Cr LVV spectra of Al/Cr alloys is commented on.The area of major disagreement regards the hypothesis that Al-alloying suppresses the Cr LVV decay. It is pointed out that the surface chemical composition of the alloys should be considered in detail, and that instrumental factors and the presence of surface contamination would account for the negligible Cr LVV intensity.     

Ultracold Gases and Quantum Information: Lecture Notes of the Les Houches Summer School in Singapore,edited by C. Miniatura,L-C. Kwek,M. Ducloy,B. Grémaud,B-G. Englert,L.F. Cugliandolo,A. Ekert and K. K. Phua

Measurements of the Faraday magneto-optical effect and of optical absorption in magnetic garnet crystals and films are reviewed. Earlier work was restricted to measurements in the visible spectrum; these measurements showed that the transparency was sufficient to allow magnetic domains to be studied in relatively thick slabs. Within the last year or so interest has been renewed in extending magneto-optical measurements beyond the visible spectrum. In particular, extremely low absorptions are found in the wavelength range of approximately 1–5 microns. Thie work is, in no small way, spurred by the possibility of developing a light-beam modulator using the Faraday effect in this wavelength range. Recent measurements at very short wavelengths using garnet films are also reported. By extending the short wavelength measurements to 3000 Å, about two orders of magnitude increase in Fareday rotation and optical absorption are observed, compared with the visible spectrum measurements.

The Faraday effect has been used to measure magnetic hysteresis loops in single-crystal garnet slabs. Magneto-optical observation of the corresponding domain structures shows them to be particularly simple. Detailed correlation of domain structure and hysteresis loops is described; in addition, an estimate of the domain wall energy and its width is made from these measurements.

The garnets referred to in this review are yttrium iron garnet (YIG), gadolinium iron garnet (GdIG), and YIG doped with gallium (YGaIG).     

A Journey through Statistical Physics. Selecta of Jürg Fröhlich,edited by G. Felder,G.M. Graf and K. Hepp

Current activity in the field of magnetic separation is reviewed in fundamental terms. The diverse subject matter is ordered into four main groupings whose characteristics are described in terms of numerous devices, both of present-day and historical significance. Existing as well as potential areas of scientific and commercial operation are discussed. The basic principles of recent major developments in high intensity magnetic Separation are closely examined.