Multiple wavelength bidirectional transmission for subscriber loop applications

A laboratory demonstration of two uniwavelength bidirectional transmission systems, one at 780 nm and another at 1300 nm, multiplexed on a standard single-mode fibre is described. Based on experimental results, a duplex-quadruplex system for the subscriber loop is possible, which again doubles the information carrying capacity of the fibre system.<>     

Collection of semen from men in acute phase of spinal cord injury

In chronic spinal cord injury, semen obtained by assisted ejaculation is usually abnormal. We have assessed electroejaculation early after injury in seven patients. There were no adverse effects. Initial samples contained few or no spermatozoa but as patients emerged from spinal shock, semen improved and five had specimens cryopreserved. Thereafter sperm motility and viability decreased towards the pattern of chronic spinal cord injury by day 16. Cryopreservation was not possible in one patient with many medical complications and another who started electroejaculation 15 days after injury. Semen storage within the first 2 weeks after spinal cord injury is recommended for future fertility treatment.     

Constitution of Bone China: I, High-Temperature Phase Equilibrium Studies in the System Tricalcium Phosphate—Alumina—Silica

This investigation represents a first attempt to interpret the thermal behavior and constitution of bone china by means of a phase diagram of an idealized system. A consideration of the Tricalcium phosphate-alumina-sica phase diagram in relation to the quaternary system lime-alumina-phosphorus pentoxide-silica indicates that the composition of a normally tired commercial bone china body is β-tricalcium phosphate and anorthite in a siliceous glassy matrix. X-ray examinations of many such bodies confirm this interpretation. This preliminary investigation indicates the most profitable fields for further research.     

Energy transfer (deazaflavin-->FADH2) and electron transfer (FADH2-->T <> T) kinetics in Anacystis nidulans photolyase

DNA photolyases catalyze the photocycloreversion of cyclobutane pyrimidine dimers. The enzyme from the cyanobacterium Anacystis nidulans contains two chromophores, 1,5-dihydroflavin adenine dinucleotide (FADH2) and 7,8-didemethyl-8-hydroxy-5-deazariboflavin (8-HDF). The photophysical/photochemical reactions leading to DNA repair were investigated by using time-resolved and steady-state fluorescence spectroscopy. It was found that the excited singlet state of 8-HDF transfers energy to FADH2 at a rate of 1.9 x 10(10) s-1 and a quantum yield of 0.98. Using the Forster equation for long-range energy transfer and assuming random orientations of the donor and acceptor the interchromophore distance was calculated to be 15 A. The excited singlet FADH2 which forms either by energy transfer from 8-HDF or by direct absorption of a photon has a lifetime of 1.8 ns in the absence of substrate and 0.14 ns in the presence of the photodimer indicating electron transfer from the FADH2 excited singlet state to the dimer at a rate of 6.5 x 10(9) s-1 and quantum efficiency of 92%.