A study of the reactions γp→ωp and γp→ωp and γp→ωΔ+

The differential and total corss sections and the decay density matrix elements have been measured for the reactions, γp→ωp and γp→ωΔ⁺ (1232) in the photon energy range 2.8 to 4.8 GeV. The total cross sections for ωΔ⁺ (1232) photo-production are found to be slightly larger than those for elastic ω photo-production in this energy range. The data are compared to the predictions of a theoretical model and the contributing exchange mechanics are discussed.     

Intra-nuclear cascading in deep inelastic scattering of 150 GeV muons in emulsion

An experimental search is presented for the existence of intra-nuclear cascading which, for small values of the Bjorken scaling variable ω, is the only mechanism of particle multiplication in the target nucleus. Our data indicate that cascading does exist as one of the effective mechanisms of particle multiplication in μ-nucleus collisions. No significant variation of the observed multiplicity with ω is observed.     

Enclathration of morpholinium cations by Dianin's compound: salt formation by partial host-to-guest proton transfer

In spite of partial deprotonation upon inclusion of morpholine, Dianin's compound maintains its well-known clathrate structure in the solid state.     

Organic crystals absorb hydrogen gas under mild conditions

We have studied the hydrogen sorption on three well-known organic hosts that possess vacant lattice voids large enough to accommodate H2 molecules.     

Efficient algorithms for the matrix cosine and sine

Several improvements are made to an algorithm of Higham and Smith for computing the matrix cosine. The original algorithm scales the matrix by a power of 2 to bring the ∞-norm to 1 or less, evaluates the [8/8] Padé approximant, then uses the double-angle formula cos (2A)=2cos ²A−I to recover the cosine of the original matrix. The first improvement is to phrase truncation error bounds in terms of ‖A²‖^1/2 instead of the (no smaller and potentially much larger quantity) ‖A‖. The second is to choose the degree of the Padé approximant to minimize the computational cost subject to achieving a desired truncation error. A third improvement is to use an absolute, rather than relative, error criterion in the choice of Padé approximant; this allows the use of higher degree approximants without worsening an a priori error bound. Our theory and experiments show that each of these modifications brings a reduction in computational cost. Moreover, because the modifications tend to reduce the number of double-angle steps they usually result in a more accurate computed cosine in floating point arithmetic. We also derive an algorithm for computing both cos (A) and sin (A), by adapting the ideas developed for the cosine and intertwining the cosine and sine double angle recurrences. AMS subject classification 65F30 Numerical Analysis Report 461, Manchester Centre for Computational Mathematics, February 2005. Gareth I. Hargreaves: This work was supported by an Engineering and Physical Sciences Research Council Ph.D. Studentship. Nicholas J. Higham: This work was supported by Engineering and Physical Sciences Research Council grant GR/T08739 and by a Royal Society–Wolfson Research Merit Award.     

Coal Handleability — A good or a bad coal?

The avalanching behaviour of two coal types was determined, one of good and the other of poor handleability characteristics. This revealed significant differences in the nature of flow of the coals. Analysis of the strange attractors of the weight series of avalanches enabled quanitification of this difference, and the establishment of practical, relative criteria for the measurement of coal handleability. These criteria will now enable a structured study of the variables that affect handleability, for example proportion of fines and moisture content, and industrial consumers of coal to specify minimum acceptable limits for its transport characteristics.     

Probing the substrate specificity of the catalytically self-sufficient cytochrome P450 RhF from a Rhodococcus sp

Analysis of the substrate specificity of the self-sufficient cytochrome P450 RhF revealed that the enzyme tends to catalyse the dealkylation of substituted alkyl-aryl ethers with shorter alkyl moieties more readily than equivalent compounds with longer alkyl groups.     

Reversible lithium insertion and copper extrusion in layered oxysulfides

All of the copper in the layered oxysulfides Sr2MnO2Cu1.5S2 and Sr2MnO2CU3.5S3 may be extruded as the element and the copper ions replaced quasi-reversibly by lithium ions in reductive topotactic ion exchange reactions; dramatic changes in magnetic properties result.