Interactions of dispersion-managed solitons in wavelength-division-multiplexed optical transmission lines

We investigate interactions between pulses in dispersion-managed multichannel wavelength-division-multiplexed soliton systems, using an improved variational approximation. The frequency shifts are found to be smallest for moderate, i.e., relatively short-scale, dispersion management. The position shifts increase monotonically with map strength.     

Background vapor from six ionic liquids and the partition coefficients and limits of detection for 10 different analytes in those ionic liquids measured using headspace gas chromatography

The concentration and identity of the compounds detected in the vapor above six ionic liquids by headspace gas chromatography (HS-GC) at 100 degrees C are reported. In addition, the partition coefficients for 10 different compounds in these ionic liquids and limits of detection were measured. These results provide quantitative guidance for the application of ionic liquids for HS-GC.     

Niedermolekulare diorganozinn-sauerstoff-verbindungen: di-t-butyl- und di-t-amylzinnoxid

Di-t-butyltin oxide (t-Bu₂SnO)₃ and di-t-amyltin oxide (t-Am₂SnO)₃ were synthesized by hydrolysis of the diorganotin dichlorides. Their molecular and crystal structures were investigated by X-ray diffraction techniques and vibrational spectroscopy. Both compounds form isolated molecules with planar six-membered tin-oxygen rings.     

Increase of the Specific Absorption Rate (SAR) by Magnetic Fractionation of Magnetic Fluids

Magnetic fractionation was applied to a common magnetic fluid based on superparamagnetic iron-oxide nano-particles with core radius of 5nm. The fractions collected were investigated with respect to particle-sizes and the influence of fractionation on the specific absorption rate, in order to optimize magnetic fluids for the application in hyperthermia.     

Quantum Field Theory on Spacetimes with a Compactly Generated Cauchy Horizon

We prove two theorems which concern difficulties in the formulation of the quantum theory of a linear scalar field on a spacetime, , with a compactly generated Cauchy horizon. These theorems demonstrate the breakdown of the theory at certain base points of the Cauchy horizon, which are defined as ‘past terminal accumulation points’ of the horizon generators. Thus, the theorems may be interpreted as giving support to Hawking's ‘Chronology Protection Conjecture’, according to which the laws of physics prevent one from manufacturing a ’time machine‘. Specifically, we prove: Theorem 1. There is no extension to of the usual field algebra on the initial globally hyperbolic region which satisfies the condition of F-locality at any base point. In other words, any extension of the field algebra must, in any globally hyperbolic neighbourhood of any base point, differ from the algebra one would define on that neighbourhood according to the rules for globally hyperbolic spacetimes. Theorem 2. The two-point distribution for any Hadamard state defined on the initial globally hyperbolic region must (when extended to a distributional bisolution of the covariant Klein-Gordon equation on the full spacetime) be singular at every base point x in the sense that the difference between this two point distribution and a local Hadamard distribution cannot be given by a bounded function in any neighbourhood (in M × M) of (x,x). In consequence of Theorem 2, quantities such as the renormalized expectation value of φ² or of the stress-energy tensor are necessarily ill-defined or singular at any base point. The proof of these theorems relies on the ‘Propagation of Singularities’ theorems of Duistermaat and H?rmander. Received: 14 March 1996/Accepted: 11 June 1996