Surface science studies of cobalt overlayers on clean and sulfur covered Mo(100) single crystal surfaces

The interaction of cobalt with clean and sulfur covered Mo(100) surfaces was investigated with Auger electron spectroscopy (AES), low energy electron diffraction (LEED) and temperature programmed desorption (TPD). On the clean surface, the deposition and subsequent annealing of one monolayer of cobalt resulted in the formation of an ordered overlayer with (1 × 1) surface structure. When cobalt was deposited on sulfur covered Mo(100) surfaces, after annealing the sulfur overlayer migrated on top of the cobalt layer. This topmost sulfur overlayer did not significantly affect the thermal desorption of cobalt from the Mo(100) surface. Various ordered structures of sulfur, cobalt and coadsorbed sulfur and cobalt were observed by LEED. A new surface structure showing (3 × 1) symmetry was observed when at least one monolayer of cobalt was deposited and annealed at 870 K on an ordered monolayer of sulfur on the Mo(100) surface. This surface structure was stable in ultrahigh vacuum up to 940 K.     

Direct photons at RHIC — Preliminary results and prospects

Penetrating probes like direct photons were always considered a crucial tool to study the initial conditions established in relativistic heavy ion collisions and to possibly map out the entire time history of the collision. Technically, however, the direct photon measurement is very challenging, primarily due to the large photon background from hadron decays. Now that after the first three years of RHIC operations the hadron spectra are well established there is an increased interest in the community to extract the spectrum of direct (non-hadronic) photons both from p+p, d+Au and Au+Au data. This paper reports on the currently available results and assesses what new results might be expected in the near future.     

Metodi di teoria dei gruppi nello studio delle ovali dei piani proiettivi finiti

La presente relazione è una rassegna di risultati sui gruppi di collineazioni che mutano in sé un'ovale di un piano proiettivo di ordine finito. We give an account of the subject of collineation groups of a finite projective plane which fixes an oval. Almost all of the results require deep theorems on finite groups. We will mention these and, in some cases, also outline how they come into play in the proofs.

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(Conferenza tenuta ill'11 giugno 1990)     

A decision procedure using discrete geometry

A decision procedure is given which makes essential use of concepts in discrete geometry. The procedure decides for any one-state Turing machine with three-dimensional tape, whether or not it has an immortal configuration, i.e., it solves the uniform halting problem for such devices. The history and significance of the problem is examined. The solution is given with the main motivation of showing how traditional mathematical concepts can be used in decision procedures. The paper is introductory in the sense that all notions are carefully defined.     

Stereospecific access to branched-chain carbohydrate synthons.

Appropriate precursors for the synthesis of D-vancosamine and L-evernitrose have been stereospecifically obtained from methyl 4,6-O-benzylidene-2-deoxy-α- and β-D-threo-hexopyranosid-3-ulose.     

On the extension of involutorial Bol loops

The group theoretical problem of the existence of a system of representativesT of the subgroup H of G such that T consists of conjugacy classes of involutions leads to the theory of Bol loops of exponent 2. In this paper, we develop a theory of extensions of such loops and give two applications of the theory. First, we classify all (left) Bol loops of exponent 2 of order 16; second, we classify all Bol loops of exponent 2 whose right nucleus has index 2. In particular, we give a class of examples of non-nilpotent such Bol loops. The second author was supported by the “János Bolyai” Fellowship, the Blaschke Stiftung and the OTKA grants F030737, T029849.     

Dual mean Minkowski measures of symmetry for convex bodies

We introduce and study a sequence of geometric invariants for convex bodies in finite-dimensional spaces, which is in a sense dual to the sequence of mean Minkowski measures of symmetry proposed by the second author. It turns out that the sequence introduced in this paper shares many nice properties with the sequence of mean Minkowski measures, such as the sub-arithmeticity and the upper-additivity. More meaningfully, it is shown that this new sequence of geometric invariants, in contrast to the sequence of mean Minkowski measures which provides information on the shapes of lower dimensional sections of a convex body, provides information on the shapes of orthogonal projections of a convex body. The relations of these new invariants to the well-known Minkowski measure of asymmetry and their further applications are discussed as well.