The use of existing environmental networks for the post-market monitoring of GM crop cultivation in the EU.

The European Union (EU) Directive 2001/18/EC on the deliberate release of genetically modified organisms (GMOs) into the environment requires that both Case-Specific Monitoring (CSM) and General Surveillance (GS) are considered as post-market implementing measures. Whereas CSM is directed to monitor potential adverse effects of GMOs or their use identified in the environmental risk assessment, GS aims to detect un-intended adverse effects of GMOs or their use on human and animal health or the environment. Guidance documents on the monitoring of genetically modified (GM) plants from the Commission and EFSA clarify that, as appropriate, GS can make use of established routine surveillance practices. Networks involved in routine surveillance offer recognised expertise in a particular domain and are designed to collect information on important environmental aspects over a large geographical area. However, as the suitability of existing monitoring networks to provide relevant data for monitoring impacts of GMOs is not known, plant biotechnology companies developed an approach to describe the processes and criteria that will be used for selecting and evaluating existing monitoring systems. In this paper, the availability of existing monitoring networks for this purpose is evaluated. By cataloguing the existing environmental monitoring networks in the EU, it can be concluded that they can only be used, in the context of GMO cultivation monitoring, as secondary tools to collect baseline information.

Coupling of impurity modes in one-dimensional periodic systems.

One-dimensional periodic dielectric structures are known to exhibit band gaps because of their symmetry. Defect states can be found in the band gaps if an impurity layer is added to the lattice such that the symmetry of the structure is broken. In this paper, we consider the case where a second impurity layer is added and we discuss the existence of coupling between the two defects. We discuss the possibility of exploiting the coupling of impurity modes in the realization of tunable wavelength emitting devices and dual-wavelength vertical-cavity surface-emitting lasers.

Nonlinear emission of semiconductor microcavities in the strong coupling regime

We report on the nonlinear laserlike emission from semiconductor microcavities in the strong coupling regime. Under resonant continuous wave excitation we observe a highly emissive state. The energy, dispersion, and spatial extent of this state is measured and is found to be dispersionless and spatially localized. This state coexists with luminescence that follows the usual cavity-polariton dispersion. It is attributed to the amplification of luminescence by a parametric gain due to cavity-polariton scattering. Despite the resonant excitation at 1.6 K, we observe no sign of Bose-Einstein condensation nor Boser action.

Application of Teflon-AF thin films for bio-patterning of neural cell adhesion.

Teflon AF, an amorphous copolymer of polytetrafluoroethylene (PTFE) with 2,2-bis(triflouromethyl)-4,5-difluoro-1, 3-dioxole, has been receiving widespread attention in the opto-electronics industries and elsewhere for its superior optical and dielectric properties. The objective of the present study was to investigate surface parameters that may be required for the application of thin films of Teflon AF in the fields of biomaterials and bioelectronics. Using standard microelectronics procedures, micro-patterned thin films of Teflon-AF were fabricated, and their surface properties monitored and optimized with the aid of highly surface sensitive spectrometric techniques. Finally, their capability to inhibit or bio-pattern cell adhesion was tested with various neural cell lines.

Vacuum interlock system for molecular beam epitaxy.

A vacuum interlock system which permits rapid loading of substrates for molecular beam epitaxy crystal growth is described. Substrates are introduced through a separate, independently pumped, loading chamber while maintaining the main growth chamber under vacuum, thereby minimizing contamination of the evaporation sources and reducing the downtime of the system between successive growth runs. The design permits outgassing of the substrates prior to their insertion in the growth chamber, and has provisions for a later addition of a separate sputtering or chemical etching capability.

Interference filters: single crystal multilayer AlAs-GaAs.

High and low reflectance single crystal quarter wave stacks consisting of alternating layers of AlAs and GaAs have been grown on GaAs substrates by molecular beam epitaxy.

Multilayer GaAs-Al(0.3)Ga(0.7)As dielectric quarter wave stacks grown by molecular beam epitaxy.

Single crystal quarter wave multilayer stacks consisting of alternating layers of GaAs and Al(0.3)Ga(0.7)As were grown on GaAs substrates by the molecular beam epitaxy method. This technique is capable of a very high degree of control of film thickness and layer reproducibility. The measured reflectivity spectrum is in good agreement with the reflectivity dispersion of GaAs and Alo.gGao.7As. calculated from the equivalent layer theory using the known index dispersion of GaAs and GaAs and Al(0.3)Ga(0.7)As.