The influence of nonfundamental pump modes in erbium-doped fiber amplifiers

This work analyzes how the characteristics of an erbium-doped fiber amplifier (EDFA) depends on the mode distribution of 800-nm pump light. The analysis is performed by using a large-signal model of an optimally pumped erbium-doped fiber amplifier. Special attention is given to the gain degradation, and noise figures of the amplifier for co- and counterpropagating pump light.     

Electron capture by tetra- and di-chlorobenzene molecules. Comparative studies by position annihilation and ODESR methods

Experiments on inhibition and anti-inhibition of Ps formation and also on optical detection of ESR spectra in squalene solutions with 1,2,4,5-C₆H₂Cl₄ and p-C₆H₄Cl₂ have demonstrated the presence of short-lived molecular radical-anions (products of the spur electron capture by additives), their lifetimes being longer than roughly 10 ps and shorter than 10–30 ns. The cross section of electron capture by p-C₆H₄Cl₂ in squalane is nearly one-tenth of that by 1,2,4,5-C₆H₂Cl₄ and CCl₄ at concentration ? 0.02 M, while 10% of the electrons cannot be trapped even at 0.25 M p-C₆H₄Cl₂. Probably the electrons in the high-electric-field (0.3–3 MV/cm) regions of the spurs cannot be effectively captured by p-C₆H₄Cl₂, which is a shallow electron trap. Similar effects of the high electric fields of the charged spur series seem to influence the Ps formation appreciably, along with the other effects discussed in previous papers. Several new results can be predicted, by use of this interpretation. Both methods employed are emphasized to be selective with respect to geminate spur particles.     

Mercury and cadmium concentrations in milk in Puerto Rico

Milk was collected over a four-month period from three representative sectors of Puerto Rico. Instrumental neutron activation analysis (INAA) performed on the samples showed that the mercury concentration was slightly higher than the safe upper limit set by the World Health Organisation on food products. INAA for cadmium yielded high values when compared with atomic absorption.     

Sub-Stonean spaces and corona sets

A self-contained account of the theory of sub-Stonean spaces, and their relations to Stonean spaces and Rickart spaces is given. Of particular interest are the corona sets (of the form β(X) for locally compact, σ-compact spaces, because these highly nontrivial sub-Stonean spaces lend themselves to C?ech-cohomological considerations. The theory of sub-Stonean spaces is essential for our solution of the diagonalization problem for C(X)? M_n, found in K. Grove and G. K. Pedersen, Diagonalizing matrices over C(X), submitted for publication.