Topological and metric properties of infinite clusters in stationary two-dimensional site percolation

A dependent percolation model is a random coloring of the two-lattice. It is assumed that there are a finite number of colors and that the coloring is translation invariant. Each color defines a random subset of the lattice. Connected components of this subset are called clusters. This paper gives a classification of the infinite behavior of these clusters. In particular, it is shown that the lattice is divided into disjoint infinite strips, lying adjacently. Each strip is either composed of an infinite cluster together with isolated finite clusters or else is entirely composed of finite clusters. Examples of the various types of behavior are constructed.     

A mixingT for whichT-T −1 is Bernoulli

We show that if σ is the Bernoulli shift on sequences of {?1, 1} with equiprobable product measure andT is a suitable mixing entropy zero trnsformation then the skew product defined byS(x,y)=(σx,T ^x0 y) is Bernoulli.     

Rapid FTIR sensing of volcanic gases released by Strombolian explosions at Yasur volcano, Vanuatu

We report here the results of a field campaign in which a portable Fourier transform infrared (FTIR) spectrometer was used to measure gas emissions from Yasur volcano, Vanuatu, in January 2005. By collecting FTIR spectra at a high rate (about 1 Hz), we were able to observe a marked difference in the proportions of SO₂ and HCl in emissions released during Strombolian eruptions (SO₂/HCl molar ratio up to ∼30 or more) compared with the intervening passive emissions discharged from the magmatic vent (SO₂/HCl ∼2). This contrast can be explained by sourcing gas at different depths with respect to levels at which SO₂ and HCl exsolve from the melt: deeper volatile exsolution supplies relatively SO₂-rich gas responsible for the ephemeral explosions at the top of the conduit; while degassing of shallow magma, depleted in sulfur but rich in chlorine, contributes to the passive emission. PACS 07.57.Ty; 91.40.Vg; 91.40.Yt; 91.40.Zz     

The role of accurate ab initio calculations in the determination of the repulsive wall of the HeHe potential

Accurate ab initio Cl calculations of interaction energies for He-He are shown to continue to be invaluable for the interpretation and assessment of experimental data for this system in both the low-and high-energy, part of the repulsive wall.     

Railgun experiments with Lexan insulators

A series of railgun experiments has been performed using Lexan insulators in both round and square bores, and with closed-breech and open-breech/injected configurations. Measured armature lengths have been roughly constant at 5-10 cm in a 1-cm bore for all Lexan insulator shots, indicating that the ablated Lexan is not swept up. Projectiles have been observed to reach peak velocity of 5.65 km/s with clean armature structures: i.e. no separated secondary arc or restrike. However, in most cases a secondary arc does occur with Lexan and limits the achievable velocity. Occasionally, stationary secondary arcs have also been observed for a particularly leaky gun assembly. The effect of insulator ablation on performance is discussed, indicating that Lexan may be useful at up to 8-10 km/s for well-sealed railguns     

Synthesis of 4-azido-2-isopropylamino-6-ethylamino-s-triazine (ring UL14C)

Radioactive 4-azido-2-isopropylamino-6-ethylamino-s-triazine (¹⁴C triazine ring) was synthesized for use as a photoaffinity label to study the site of triazine action in the chloroplast. It was prepared from ¹⁴C 4-chloro-2-isopropylamino-6-ethylamino-s-triazine by forming the trimethylamine salt followed by treatment with sodium azide. ¹⁴C azidotrazine, 6.6 mg, was obtained in a yield of 64% based on ¹⁴C atrazine. The specific activity was 37.4 μCi/mg, and it assayed over 99.5% radiochemically pure after purification by TLC.     

An Automatic Model for Purchase Decisions

The paper describes a decision-making model to control the entire expenditure by Rolls-Royce Aero Engine Division with outside suppliers. The project began as an “investigation into economic order quantities”, and expanded into an automatic decision-making package for determining the size of orders to be placed on suppliers, the length of time into the future these orders should stretch, the best price break information to ask for, and the extent to which changes in demand within Rolls-Royce should be suppressed to cushion the suppliers from unnecessary fluctuations. A conservative estimate of savings which result from implementing a model of this nature is that the purchase bill is reduced by at least 5 per cent and the inventory by somewhere in the region of 15 per cent.