A family of à n -groups

For each integern≥2 and for each prime powerq, we exhibit a group Γ which acts simply transitively on the set of vertices of the building of type à _n associated with the local field $\mathbb{F}^q ((Y))$ . This generalizes work in [2] and [8] (wheren=2) and in [1] (wheren≤4).     

Methodological information from the certification of CCRMP ores and concentrates

In the course of 90 certifications for 27 elements in 26 reference ores and concentrates, carried out by the Canadian Certified Reference Materials Project, much methodological information has been documented and is now made available to analysts for the selection of suitable methods for the analysis of specific materials. Information is presented for copper, gold, lead, silver, sodium, potassium, tin, tungsten, uranium and zinc. A relationship between the average coefficient of variation and element concentration makes it possible to make some generalizations about the precision to be expected for a given concentration of an element in ores and concentrates.     

Oxidation of sulphide minerals--I: determination of ferrous and ferric iron in samples of pyrrhotite, pyrite and chalcopyrite

A method has been developed for determining small amounts of both ferrous and ferric iron in oxidized samples of pyrrhotite, pyrite and chalcopyrite. The oxidized iron is selectively dissolved in 10M phosphoric acid under reflux and can be determined with the accuracy generally accepted in chemical phase analysis.     

The random planar graph process

We consider the following variant of the classical random graph process introduced by Erd?s and Rényi. Starting with an empty graph on n vertices, choose the next edge uniformly at random among all edges not yet considered, but only insert it if the graph remains planar. We show that for all ε > 0, with high probability, θ(n²) edges have to be tested before the number of edges in the graph reaches (1 + ε)n. At this point, the graph is connected with high probability and contains a linear number of induced copies of any fixed connected planar graph, the first property being in contrast and the second one in accordance with the uniform random planar graph model. © 2007 Wiley Periodicals, Inc. Random Struct. Alg., 2008     

Analysis of building stone decay by computer assisted IR spectroscopy

The development of an automatic identification system for infrared spectra of inorganic sulphates and the first results are briefly described.     

An Extremal Problem For Random Graphs And The Number Of Graphs With Large Even-Girth

C _{2 k} -free subgraph of a random graph may have, obtaining best possible results for a range of p=p(n). Our estimates strengthen previous bounds of Füredi [12] and Haxell, Kohayakawa, and Łuczak [13]. Two main tools are used here: the first one is an upper bound for the number of graphs with large even-girth, i.e., graphs without short even cycles, with a given number of vertices and edges, and satisfying a certain additional pseudorandom condition; the second tool is the powerful result of Ajtai, Komlós, Pintz, Spencer, and Szemerédi [1] on uncrowded hypergraphs as given by Duke, Lefmann, and R?dl [7]. Received: February 17, 1995