Maximizing a congruence with respect to its partition of idempotents

For a congruence σ on a semigroupS a congruence μ(σ) onS, containing σ, is defined such that the semigroupS/σ is fundamental if and only if σ=μ(σ). The congruence μ(σ) is shown to possess maximality properties and for idempotent-surjective semigroups, μ(σ) is the maximum congruence with respect to the partition of the idempotents determined by σ. Thus μ is the maximum idempotent-separating congruence on any idempotent-surjective semigroup. It is shown that μ(μ(σ))=μ(σ). If ρ is another congruence onS, possibly with the same partition of the idempotents as σ, then it is of interest to know when ρ⊆σ (or ρ⊆μ(σ)) implies μ(ρ)⊆μ(σ) or even μ(ρ)=μ(σ). These implications are not true in general but if σ⊆ρ⊆μ(σ) then μ(ρ)⊆μ(σ). IfS is an idempotent-surjective semigroup and ρ and σ have the same partition of the idempotents then μ(ρ)=μ(σ).     

Analysis of the inclusive reaction π−p→K10 (890) X0 at 10 GeV/c

Experimental results on the reaction $\text{π}{}^{\mathrm{?}}\text{p}\text{→}\text{K}{}^{10}\text{(890)}\text{X}{}^0\text{at}\text{10}\text{GeV}\text{/c}$ are presented. By using the K¹⁰ polarization measurements, a detailed study of the production has been carried out as a function of the missing mass squared and of the four-momentum trasnfer squared to the K¹⁰. We found that: (a) K¹⁰ production is dominated by natural parity exchange; (b) K¹⁰ helicity-zero production dominates the unnatural parity exchange contribution and (c) the main features of the reaction are in agreement with the predictions of the finite mass sum rules.     

A generalized restricted open-shell Fock operator

We reexamine the open shell restricted Hartree-Fock theory and develop Fock-like operators that are quite general and easy to implement on a computer. We present a table of vector coupling coefficients that define this operator for most of the cases that commonly arise. We compare the form of this operator with that suggested by others, and discuss the orbitals obtained by this procedure with respect to the generalised Brillouin's theorem, and the orbital energies with respect to Koopmans' approximation.Dedicated to Professor J. Koutecký on the occasion of his 65th birthday     

Analysis and Implications of Management Uses of Information

It is a prerequisite to a number of management orientated disciplines that a manager's needs for information are defined. An initial stage in being able to adequately define needs is to understand the ways in which information can affect management behaviour. Several ways are suggested in this paper and from these, implications are drawn which are of relevance to designers of information systems.     

Borrowing hydrogen: a catalytic route to C-C bond formation from alcohols

Ruthenium complexes have been shown to perform efficient transfer hydrogenation reactions between alcohols and alkenes; in combination with an in situ Wittig reaction, indirect formation of C-C bonds has been achieved from alcohols.     

Palladium(II) complexes of new OPN phosphine ligands and their application in homogeneously catalysed reactions of CO with alkenes or alkynes

Palladium complexes of a series of functionalised phosphines bearing the OPN donor set [2-pyCH(2)P(Ph)CH(2)(CHOCH(2)CH(2)CH(2)), 1; 2-py CH(2)P(Ph)-CH(2)CH(2)(CHOCH(2)CH(2)O), 2; 2-pyCH(2)P(Ph)CH(2)CH(2)CO(2)Me, 3; 2-pyP(Ph)CH(2)(CHOCH(2)CH(2)CH(2)), 4; 2-py = 2-pyridyl] have been prepared and characterised. Ligands 1-3 form five membered P-N chelates which is confirmed for PdCl(2) complexes of and by X-ray crystallography. O-coordination appears to be generally disfavoured although there is evidence of transient O-coordination for selected Pd complexes of 4. Palladium methyl and acetate complexes of all four ligands have been tested for catalytic activity in ethene/CO copolymerisation as well as alkoxy-carbonylation of propyne. Complexes of 1 and 4 show some activity in the copolymerisation reaction and complexes of 4 are active in the methoxy carbonylation of propyne. Unlike related pyridyl(diaryl)phosphines, 4 produces a much more stable catalyst system that does not require large excesses of ligand to maintain activity.     

Stationary equilibria of two fluid plasmas having significant, internal, static electric fields

New steady-state equilibria of two-species, collisionless plasmas have been found for symmetrical systems by varying the total energy subject to Maxwell's equations, momentum moment equations, and adiabatic equations of state, without imposing a quasineutrality condition. Electrons are confined by magnetic forces and ions by internal, electrostatic forces due to charge separation. The scale length for one-dimensional plasmas is characterized by the electron skin depth. Minimum average beta values are approximately one-half. Space and laboratory applications are discussed.     

Absolute frequency measurement of a 1.5-microm acetylene standard by use of a combined frequency chain and femtosecond comb

We have developed and characterized a pair of Doppler-free acetylene-stabilized diode laser frequency standards as optical communications references. The Allan deviation sigma/f of an individual system reaches a minimum of 4 x 10(-14) at a sampling time of 5000 s, and the long-term lock-point repeatability is found to be 0.4 kHz (one standard uncertainty), corresponding to a fractional uncertainty of 2 x 10(-12). Using a combination of a frequency chain and a self-referenced femtosecond comb, we have measured the frequency of line P(16) of the v1 + v3 overtone band of 13C2H2 to be 194,369,569,385.9 (3.0) kHz. The uncertainty of this number is limited solely by the reproducibility of the standards.