A review of: “Optical technology and wideband local area networks”

London: The Royal Society,     

A review of: “Techniques of high energy physics”

Edited By David M. Ritson. (Interscience Publishers, 1961.) [Pp. xii+540.] 126s     

Classical “freezing” of plane rotations: A proof of the Boltzmann-Jeans conjecture

Using simple known methods and results of classical perturbation theory, especially those due to Nekhoroshev and Neishtadt, we study the energy exchanges between the rotational and the translational degrees of freedom in a particular model representing the planar motion of a rigid body in a bounded analytic potential. We prove that, if the angular velocity is initially large, then the energy exchanges are small,O( ^–1), for times growing exponentially with, |t|exp. We also deduce that in a scattering process from a (smooth) potential barrier, the overall change in the rotational energy of the incoming body is exponentially small in, exp(–. The results are interpreted in the light of an old conjecture by Boltzmann and Jeans on the existence of very large time scales for equilibrium in statistical systems containing high-frequency degrees of freedom (purely classical freezing of the high-frequency degrees of freedom); the rotating object is, in this interpretation, a (classical) molecule, which moves in an external field, or collides with the wall of a container. Two different limits of large are considered, namely the limit of large rotational energy, and (as is interesting for the molecular interpretation) the limit of point mass, at finite rotational energy.     

A review of: “Advances in phase transitions”

From specific heat, thermal expansion, and dielectric constant measurements between 150 and 300 K we have confirmed the low temperature phase transition in barium chloride dihydrate (BaCl₂.2H₂O) at 195 ± 1 K. This transition appears to be associated with the local ordering (or displacements) of the two water molecules in the crystal. A “pseudospin” type model is proposed to explain the transition mechanism.     

A review of: “Environmental Behaviour of Crop Protection Chemicals”

Abstract

Proceedings of an International Symposium on the Use of Nuclear and Related Techniques for Studying Environmental Behaviour of Crop Protection Chemicals Jointly Organized by the International Atomic Energy Agency and the Food and Agriculture Organization of the United Nations and held in Vienna, 1–5 July 1996. IAEA Vienna 1997, 519 pp.     

A review of: “Harmonization of Health Related Environmental Measurements Using Nuclear and Isotopic Techniques”

Abstract

Proceedings of an International Symposium Organized by the International Atomic Energy Agency and Held in Hyderabad. India, 4–7 November 1996. IAEA Vienna 1997, 663 pp.     

A review of: “Isotopes in Water Resources Management”

Abstract

Proceedings of the International Symposium, organized by the IAEA, in co-operation with UNESCO, Vienna, 20–24 March 1995. Vol. 1 (ISBN 92-0-105595-1) and Vol. 2 (ISBN 92-0-100796-5), edited by IAEA, Vienna, Austria, March 1996.     

A review of: “Australian academy of science silver jubilee symposia”

Vols. i-iii (a$7.50 each)     

A brief review of “granular elasticity”

Although granular materials are predominantly plastic, preparation-dependent, anisotropic under shear, and incrementally nonlinear, their static stress distribution is well accounted for, in the whole range up to the point of failure, by an isotropic, nonlinear and carefully tailored elasticity theory termed GE, for "granular elasticity". Its usefulness, limits, and the understanding behind it are reviewed, and some contentious questions (e.g. what is the elastic reference state, how to measure the elastic displacement) discussed.     

A review of: “Surface effects in controlled fusion devices”

Proceedings of the second conference on surface effects in controlled fusion devices, San Francisco, USA, February 1976. (Eds. W. Bauer, C. R. Finfgeld and M. Kaminsky). North Holland (Amsterdam), 534 pages. US $120.50.     

A review of: “The science of crystallization,microscopic interfacial phenomena”

Abstract

By W. A. Tiller, Cambridge University Press. ISBN 0-521-38827-9     

A review of: “Comparative crystal chemistry: temperature,pressure, composition and the variation of crystal structure”

By R. M. Hazen and L. W. Finger. Wiley (1982). Price: £19.50 (U.K.)     

Structure and magnetism of Co:CoO core–shell nanoclusters

Transmission electron microscopy (TEM) and electron diffraction (ED) are used to investigate the nanostructures of two ensembles of Co:CoO core–shell particles. TEM images show that particles of size about 12 nm are almost fully oxidized, while particles with size about 18 nm have a core–shell structure where a Co core is surrounded by a shell of CoO. ED simulation confirms that the larger particles have an fcc-structured Co core and a rock-salt CoO shell structure, while the smaller particles mostly have the rock-salt CoO structure. The core–shell structure is responsible for the unusual magnetic properties of the Co:CoO nanoclusters, especially the occurrence of inverted hysteresis loops (proteresis), but previous research has been indirect, largely based on magnetic measurements and on a cross-comparison with granular materials. Our measurements show that the structures have ferromagnetic fcc Co cores of varying sizes down to 1 nm which are surrounded by antiferromagnetic rock-salt CoO shells. The core radii obtained from the TEM pictures are used to estimate the exchange interactions responsible for proteresis and to pinpoint the core-size window in which proteresis occurs.     

A review of: “Ordering in strongly fluctuating condensed matter systems”

Abstract

Ed. T. Riste. (Nato Advanced Study Institutes Series, Vol. 50). Plenum, Price: $55 (U.S.)     

A Classical Formulation of Quantum Theory?

We explore a particular way of reformulating quantum theory in classical terms, starting with phase space rather than Hilbert space, and with actual probability distributions rather than quasiprobabilities. The classical picture we start with is epistemically restricted, in the spirit of a model introduced by Spekkens. We obtain quantum theory only by combining a collection of restricted classical pictures. Our main challenge in this paper is to find a simple way of characterizing the allowed sets of classical pictures. We present one promising approach to this problem and show how it works out for the case of a single qubit.