Quark confinement in the two-dimensional lattice Higgs-Villain model

We prove quark confinement in the two-dimensional lattice Higgs-Villain model in the weak coupling region by using a Kirkwood-Salsburg equations for unbounded spins.Research partially supported by the National Science Foundation under Grant PHY-77-18762On leave from Department of Mathematics, University of British Columbia, Vancouver, B.C., Canada. Research partially supported by National Research Council under Grant A4015On leave from Istituto di Fisica Teorica, Napoli, Italy     

The electronic viewpoint on the morphology of the microclusters

Although the five-fold symmetry conflicts with the crystalline long range order, it can appear in some finite systems. In order to search for such possibility in the microclusters in the small size limit and to clarify the roles of the electrons in the morphology, the electronic states are studied in the tight binding scheme. The single electron spectra coming from thes- andp-atomic orbitals are derived for three types of the 13-atom clusters; with the fcc-like configuration, the hcp-like and the icosahedral. If the transfer integral between two surface atoms is put equal to that between the central and a surface atom in the icosahedral case, this configuration has the lowest total electronic energy in many cases studied, but not always. The fact that a surface atom has larger number of neighbours in the icosahedral configuration is surely of great advantage. It, however, is not almighty in the quantum case.On leave from Department of Physics, Faculty of Science, Kyoto University, Kyoto 606, Japan. A part of this work was done there     

New types of periodic structures in laser-induced chemical vapor deposition

New types of periodic structures that occur in laser-induced chemical vapor deposition have been investigated, mainly for polycrystalline Si deposited on glass substrates covered with a thin amorphous Si layer. These periodic structures, which are believed to be a general phenomenon in pyrolytic laser-induced processing, limit the resolution obtainable in direct writing of patterns.On leave from Fudan University, Department of Electronic Engineering, Shanghai, People's Republic of China     

Negative feedback using a nonlinear mirror for the generation of a long train of short light pulses

A nonlinear mirror is used to provide a passive negative feedback in an actively mode-locked pulsed Nd:YAG laser. Trains of 250 ps pulses with a total length of up to 50 microseconds were generated. The train duration is limited only by the flashlamp pump pulse length.On leave from Department of Physics, University of Sofia, BG-1126 Sofia, Bulgaria     

Influence of alloy composition on the diffusivity-mobility ratio in n-channel inversion layers on ternary semiconductors

An expression is derived for the diffusivity-mobility ratio of the carriers in n-channel inversion layers on semiconductors like the ternary compounds which have strongly non-parabolic energy bands. The dependence of the ratio on alloy composition is also studied under the weak-field limit taking n-channel Hg_1–xCd_x.Te as an example.On leave of absence fromthe Department of Physics, Patna University, Patna, India.     

States on Clifford algebras

We study states on Clifford algebras from the point of view of C*-algebras. A criterium is given under which the odd-point functions vanish. A particular set of states, called quasi-free states is extensively studied and explicit representations are given; as an application we give an approximate calculation of the ground state of a Fermion system.On leave from Matematisk Institut, University of Aarhus, Denmark.Aangesteld navorser van het Belgisch N. F. W. O. On leave from University of Louvain, Belgium.     

Free energy of gravitating fermions

We calculate rigorously, in a suitable thermodynamic limit, the free energy of a system of nonrelativistic fermions which interact with attractiver ^–1-potentials. It is shown that the effective field approximation becomes exact in this limit and results in the temperature-dependent Thomas-Fermi equations.On leave of absence from the University of Heidelberg, Germany.On leave of absence from the University of Vienna, Austria.     

Szekeres's space-times have no Killing vectors

Szekeres obtained some exact solutions of Einstein's equations for dust which have applications in cosmology, in the theory of collapse, and in the study of gravitational radiation. It is shown that in their most general form these space-times have no Killing vectors.Dedicated to Achille Papapetrou on the occasion of his retirement.On leave from the Department of Mathematics, University of Malaya, Kuala Lumpur, Malaysia.Supported by the Public Services Department, Government of Malaysia.On leave from Centro Brasileiro de Pesquisas Fisicas.     

Investigations on five iron meteorites

In the present paper, we report an analysis of five iron meteorites belonging to the private collection of the mineralogy museum of the University of Parma (Italy). The collection is made up of eighteen samples, collected over two centuries. Up to now, they have never been studied by spectroscopical techniques and their classification was estimated on the basis of morphological inspection. Electron microscopy (SEM), X-ray diffraction (XRD), X-ray fluorescence (XRF), and Mössbauer spectroscopy (MS) have been used to analyse the samples.On leave from: Department of Physics, East China Normal University, Shanghai, PR China.On leave from: Department of Biol. Sci. and Biothec., Tsinghua University, Beijing, PR China.     

Effect of a quantizing magnetic field on the capacitance of MOS structures of small-gap semiconductors

An attempt is made to investigate the effect of a quantizing magnetic field on the capacitance of MOS structures of small-gap semiconductors havingn-channel inversion layers under the weak electric-field limit. It is found, takingn-channel InSb as an example, that both the MOS and surface capacitances show spiky oscillations with changing magnetic field. It is further observed that the sharpness and the depths of the spikes increase with increasing magnetic field whereas the depths are found to decrease with increasing thickness of the insulating layer. On leave of absence from the Department of Physics, Patna University, Patna, India     

On the convergence of exponential operators—the Zassenhaus formula,BCH formula and systematic approximants

The convergence of the Zassenhaus formula is proven under an appropriate condition as well as for other exponential operators such as the Baker-Campbell-Hausdorff formula.On leave of absence from Department of Physics, Faculty of Science, The University of Tokyo, Hongo, Bunkyo-ku, Tokyo, Japan     

On a global existence theorem for the Enskog equation

In this note we prove global existence of mild solutions of the Enskog equation with small initial data.On leave from Department of Mathematics and Mechanics, University of Warsaw. Warsaw, Poland.     

Cosmological model with heat flow

An earlier work on a generalized Robertson-Walker-Friedmann metric with radial heat flow is extended to any arbitrary motion.On leave from Mathematics Department, Quaid-i-Azam University, Islamabad, Pakistan.     

Double-dual solutions of generalized theories of gravitation

Solutions to the Stephenson-Yang theory of gravity and its generalizations are discussed. By considering the inclusion of a cosmological term in the action spherically symmetric static solutions are presented that do not fall into the vacuum Einstein class. A simple double-duality ansatz is responsible for all the solutions that are discussed.On leave from the Physics Department, Middle East Technical University, Ankara, Turkey.     

Quasi-equivalence of quasi-free states on the Weyl algebra

A necessary and sufficient condition for quasi-equivalence of quasi-free factor states over the Weyl algebra is proved. The essential part of this paper is closely related to the work of Powers and Størmer on the Clifford algebra.Aspirant van het Belgisch N. F. W. O. On leave from the University of Louvain (Belgium).     

Supersymmetric quantum mechanics for inverse square potentials

Inverse square potentials are studied in the context of supersymmetric quantum mechanics.On study leave from the Department of Mathematics, University of Colombo, Sri Lanka.     

On the energy in relativistic stellar dynamics

Using the results of the preceding paper we evaluate in the post-Newtonian approximation the energy integral for a system of extended bodies with arbitrary internal structure and internal motions.On leave of absence from the Astronomy Department, University of Thessaloniki, Thessaloniki, Greece.     

Exponential clustering for long-range integer-spin systems

By using Kirkwood-Salsburg equations for classical spin systems with unbounded integer values we prove exponential decay (resp. power law decay) for exponential (resp. power law) decaying potentials. We use these results to prove the mass gap in the two-dimensional Higgs-Villain model in the weak coupling region.Research partially supported by the National Science Foundation under Grant PHY-77-18762On leave from Department of Mathematics, University of British Columbia, Vancouver, B. C., Canada. Research partially supported by National Research Council under Grant A4015On leave from Istituto di Fisica Teorica, Napoli, Italy     

Quasi-free states and automorphisms of the CCR-algebra

We show that any automorphism of the CCR algebra, leaving the quasi-free states globally invariant, is monoparticular.Aspirant van het Belgisch N.F.W.O. On leave from University of Leuven K.U.L. (Belgium). Partially supported by F.O.M.     

Signals from the future

Advanced interactions do not lead to dynamical inconsistencies in closed systems. They are, however, incompatible with the existence of truly random processes.Work supported in part by U.S. Army Research Office (Durham).NATO Fellow. On leave from: Physics Department, Indiana University, Bloomington, Indiana 47401.