Band structure features involved in charge transfer in bonds

In contrast with previous theories, we show that the wave function near the gap between the lowest two valence bands in zinc-blend compounds is essential to describe the charge transfer characteristic of the ionic bond.     

Central simple algebras

Wedderburn’s factorization of polynomials over division rings is refined and used to prove that every central division algebra of degree 8, with involution, has a maximal subfield which is a Galois extension of the center (with Galois group Z₂⊕Z₂⊕Z₂). The same proof, for an arbitrary central division algebra of degree 4, gives an explicit construction of a maximal subfield which is a Galois extension of the center, with Galois group Z₂⊕Z₂. Use is made of the generic division algebras, with and without involution. This work was supported by the Israel Committee for Basic Research and the Anshel Pfeffer Chair.     

Quasi-particle density of states of the one-dimensional Anderson-Hubbard Hamiltonian

The quasi-particle density of states of the one-dimensional Anderson-Hubbard Hamiltonian has been calculated. The effect of correlation on the local density of states of a disordered chain is shown to depend critically on the energy region.     

Determination of the α parameter for the decay Ξ− → Λπ−

The α parameter for Ξ^? → Λπ^? decay has been determined to be α_Ξ^?=?0.462 ± 0.015, from a sample of 1.5 × 10⁵ events recorded in the CERN SPS hyperon beam. This value is 2.5 standard deviations higher than the current world average.     

The computer-related sciences (synnoetics) at a university in the year 1975

BIT Numerical Mathematics -     

Vacancy at the Si(111) unreconstructed surface: Electron states and absence of the Jahn-Teller distortion

The electron states of a vacancy at the Si(111) surface are calculated by means of a tight-binding scheme. The results for a vacancy at the surface layer show one state of A_l symmetry below the surface dangling bond band, and another doubly degenerate state of E symmetry above it. The Fermi energy at an isolated vacancy remains fixed by the surface. This allows to derive two important consequences: i) The vacancy state is a neutral one as can be shown by integrating the local density of states up to the Fermi energy. ii) The electronic charge around the vacancy has got the whole surface point symmetry and therefore a Jahn-Teller effect is not induced.     

A combinatorial approach toward the generation of ambiphilic peptide-based inhibitors of protein:geranylgeranyl transferase-1

A combinatorial synthesis of oligopeptide analogues and their evaluation as protein:geranylgeranyl transferase inhibitors is presented. The combinatorial strategy is based on the random mutation, in each new generation, of one of any of the four amino acid building blocks of which the most effective compounds of the previous generation are assembled. In this way, a progressive improvement of the average inhibitory activity was observed until the fifth generation. The most active inhibitors were found to inhibit PGGT-1 in the low micromolar range (IC(50): 3.8-8.1 microM).