Low loss mirrors for InP/InGaAsP waveguides

The loss associated with a mirror in an InP-based waveguide has been investigated. Mirror roughness and non-verticality were both significant sources of loss. Mirrors with only 1 dB loss have been produced through novel fabrication techniques.<>     

Efficient water market mechanisms to cope with water scarcity

Water markets are increasingly being relied upon as an instrument to reallocate water between competing users under conditions of water scarcity, and within an environment of fully committed water resources. Without such a reallocation new irrigation developments cannot take place and economic developments will be forgone to the detriment of rural communities. There is therefore a need for continued development of a water market mechanism to ensure that this reallocation process can take place as efficiently as possible, and to alleviate the socio-economic impact of water scarcity. Since markets are still emerging around the world it is important to learn from operating markets. This paper discusses the operational mechanism of a water exchange in Victoria, Australia, and analyses the outcome of the first five years of operation.     

Datensicherheit bei der elektronischen Auftragsvergabe

Die Richtlinien 2004/17/EG und 2004/87/EG sollen erstmals einen geschlossenen Rechtsrahmen für die elektronische Vergabe ?ffentlicher Auftr?ge bieten. Zahlreiche Lücken der Regelungen erschweren jedoch ihre Umsetzung in deutsches Recht. Der Beitrag stellt die wesentlichen technischen Rahmenbedingungen der elektronischen Auftragsvergabe dar und liefert Anhaltspunkte, wie die Vorgaben des Gemeinschaftsrechts sinnvoll umgesetzt werden k?nnen.     

Reaction between peroxidized phospholipid and protein: II. Molecular weight and phosphorus content of albumin after reaction with peroxidized cardiolipin

Peroxidized cardiolipin (diphosphatidylglycerol) reacts covalently with albumin. Incubation of albumin with increasing amounts of peroxidized cardiolipin produces a gradual increase in molecular size. Incubation with a small amount of peroxidized cardiolipin (molar ratio of cardiolipin/albumin 21) produces a mixture of complexes that differs considerably with respect to the number of cardiolipin molecules bound per molecule of albumin. With larger amounts of peroxidized cardiolipin (molar ratios of cardiolipin/albumin 54 and 114), the complexes formed seem to be of a more uniform type since the numbers of cardiolipin molecules bound per molecule of albumin are similar. No polymerization occurs for reactions in which up to at least 15 moles of cardiolipin have become bound per mole of albumin, and 20–25 moles may be bound with only very little polymerization. Only when the ratio of peroxidized cardiolipin to albumin was increased to a high value of 314 did polymerization occur. The present findings show that extensive covalent binding of peroxidized cardiolipin to albumin can occur without intermolecular crosslinking of the protein.     

Real-time measurements of semiconductor laser spectra

A technique for measuring the instantaneous spectrum of a semiconductor laser is described. Spectral fluctuations of several different devices, including three different length channel-substrate buried-crescent lasers emitting at 1.52 μm were examined. The shortest (100-μm) device showed a trend towaxds single-mode operation, and it is believed that devices of up to 70-μm length should emit predominantly in one longitudinal mode. Mode selection effects, thought to be due to reflections from the monitor diode, were observed in a 1.3-μm packaged laster. The technique has also been used to measure correlations between successive pulses, and between spectral width and mean position.     

Glasslike behaviour of polycrystalline BaTiO3 at very low temperatures

Specific heat capacity, thermal conductivity and complex dielectric constant of BaTiO₃ ceramic have been measured to temperatures as low as 0.1 K. No influence of an applied electric field on specific heat o r thermal conductivity has been detected. After removing of an applied static electric field a logarithmic time dependence of the dielectric constant has been observed.     

Effect of laser chirp on optical systems?initial tests using a 1480 nm DFB laser

Initial assessment of the effect of laser ?chirp? on optical systems is described. Measurements of the wavelength shift and its effect on the received pulse after 4 km and 80 km of dispersive fibre are presented. The results are in good agreement with simple modelling, which predicts no penalty for this system Further tests are needed to determine whether this behaviour is typical.