Design, Fabrication and Characterization of an InP-Based Tunable Integrated Optical Pulse Shaper

In this paper a tunable integrated semiconductor optical pulse shaper is presented. The device consists of a pair of arrayed waveguide gratings with an array of electrooptical phase modulators in between. It has been fabricated in InP-InGaAsP material for operation at wavelengths around 1.55 mum. Multimode inputs to the waveguide gratings are used to flatten their optical passband. We have used a new short-pulse characterization technique to fully characterize pulse shaping by the device, i.e., both the power and the phase profile. A fourfold decrease in pulse ringing was observed for the devices with flattened passbands. Moreover these devices showed a 25% increase in pulse peak power. The possibilities for using the device as a dispersion (pre-) compensator have been investigated. Pulse reconstruction could be obtained for dispersion values of up to 0.2 ps/nm. The fabrication technology of the pulse shaper is compatible with the fabrication of integrated mode-locked lasers, which makes further integration of complete arbitrary pulse generators possible.     

Cognitive Radio Design on an MPSoC Reconfigurable Platform

Cognitive Radio has been proposed as a promising technology for solving today’s spectrum scarcity problem by means of dynamic spectrum access. The multiprocessor system-on-chip (MPSoC) reconfigurable platform is proposed as an enabling technology for cognitive radio. In this paper, we propose a design methodology based on task transaction level interface for the design of cognitive radio baseband on an MPSoC reconfigurable platform. The reconfiguration of a novel, low-complexity fast Fourier transform for orthogonal frequency-division multiplexing based Cognitive Radio is used as a design case to show the effectiveness of the methodology for modelling the dynamic behavior of Cognitive Radio and facilitating the platform implementation.

Absorption and emission cross sections of Er(3+) in Al(2)O(3) waveguides

Al(2)O(3) slab waveguide films were doped with erbium using ion implantation to a peak concentration of 1.5 at. %. Prism coupling measurements show absorption caused by (4)I (15/2) ?(4)I (13/2) intra-4f transitions in Er(3+) with a maximum at 1.530 mum of 8 dB/cm. The Er(3+) absorption cross section is determined as a function of wavelength. We used the McCumber theory to derive the emission cross section spectrum from the absorption results, which we then compared with the Er(3+) photoluminescence spectrum. The peak absorption and emission cross sections are found to be 6 x 10(-21) cm(-2). The results are used to predict the optical gain performance of an Er-doped Al(2)O(3) optical amplifier that operates around 1.5 mum.     

RadEx: Integrated Visual Exploration of Multiparametric Studies for Radiomic Tumor Profiling

Better understanding of the complex processes driving tumor growth and metastases is critical for developing targeted treatment strategies in cancer. Radiomics extracts large amounts of features from medical images which enables radiomic tumor profiling in combination with clinical markers. However, analyzing complex imaging data in combination with clinical data is not trivial and supporting tools aiding in these exploratory analyses are presently missing. In this paper, we present an approach that aims to enable the analysis of multiparametric medical imaging data in combination with numerical, ordinal, and categorical clinical parameters to validate established and unravel novel biomarkers. We propose a hybrid approach where dimensionality reduction to a single axis is combined with multiple linked views allowing clinical experts to formulate hypotheses based on all available imaging data and clinical parameters. This may help to reveal novel tumor characteristics in relation to molecular targets for treatment, thus providing better tools for enabling more personalized targeted treatment strategies. To confirm the utility of our approach, we closely collaborate with experts from the field of gynecological cancer imaging and conducted an evaluation with six experts in this field.     

A low temperature scanning tunneling microscope for electronic and force spectroscopy

In this article, we describe and test a novel way to extend a low temperature scanning tunneling microscope with the capability to measure forces. The tuning fork that we use for this is optimized to have a high quality factor and frequency resolution. Moreover, as this technique is fully compatible with the use of bulk tips, it is possible to combine the force measurements with the use of superconductive or magnetic tips, advantageous for electronic spectroscopy. It also allows us to calibrate both the amplitude and the spring constant of the tuning fork easily, in situ and with high precision.     

A compact high-energy neutron spectrometer

A compact liquid organic neutron spectrometer based on a single NE213 liquid scintillator (5 cm diameter x 5 cm) is described. The spectrometer is designed to measure neutron fluence spectra over the energy range 2-200 MeV and is suitable for use in neutron fields having any type of time structure. Neutron fluence spectra are obtained from measurements of two-parameter distributions (counts versus pulse-height and pulse shape) using the Bayesian unfolding code MAXED. Calibration and test measurements made using a pulsed neutron beam with a continuous energy spectrum are described and the application of the spectrometer to radiation dose measurements is discussed.     

Patterns of non-starter microflora during ripening of selected South African Cheddar cheeses manufactured by the open-vat procedure

South African Cheddar cheese from a manufacturing plant using the open-vat procedure was sampled at intervals during maturation and analysed for selected non-starter micro-organisms using microbiological culture methods. The quantities of the micro-organisms corresponded well with reports in literature. However, the yeast and mould population were higher during the earlier stages of maturation. Heterofermentative lactobacilli, coliforms, faecal coliforms and members of theEnterobacteriaceae were encountered in low or negligible numbers, indicating good manufacturing practice and a high standard of plant hygiene. Total mesophilic counts, yeasts and moulds and total acid-formers decreased during maturation while the citrate-fermenters increased. The anaerobic spore-forming bacteria decreased rapidly to undetectable levels. Marked variation in counts was observed during the first five sampling points (from the salted curd to about 2 weeks of maturation). After an initial surge and decline, the total lactobacilli, homofermentative lactobacilli and aerobic spore-formers did not show a definite increase or decrease. The various micro-organisms followed multi-phasic sum-of-exponentials, linear and exponential patterns during maturation that were expressed in terms of mathematical equations. These equations may be used as components in the development of predictive indices for the selected cheese.     

A Study of the Combined Compaction and Drying of a Wet Crystal Mass

The combined compaction and drying of a wet crystal mass was studied using an industrial food processor and a custom built open turbo dryer setup. From extrapolation of an empirical relation for the porosity of a packed particle bed a qualitative idea of the influence of the constituent crystals an the minimum attainable porosity was obtained. It increases with increasing constituent crystal size and decreasing width of the crystal size distribution. From the experiments it was found that the compaction and size reduction of the wet crystal mass is mainly influenced by the characteristics of the premix. The compactibility and strength of the premix may be influenced by changing the saturation and the constituent crystal size and size distribution.     

Reproducible manufacturing of dye‐sensitized solar cells on a semi‐automated baseline

A fully operational baseline consisting of dedicated equipment to process nanocrystalline dye‐sensitized solar cell devices has been installed at ECN. This baseline focuses on the production of glass/glass devices with dimensions up to 10×10 cm². Present power conversion efficiencies of 6% obtained for cell areas of 2ċ5 cm² are successfully translated to 100 cm² devices with an active area of 68 cm² by application of identical cell components. The power conversion efficiency with respect to total area was 4%. Processing of a large number of devices in the baseline shows good results in terms of process reliability and yield. The overall yield for a series of 27 devices (10×10 cm²) was 96%, while 84% (22 of the remaining 26 devices) generated a cell efficiency within 7% deviation from the average value (4ċ3%). The reproducibility of the titanium dioxide (TiO₂) colloid synthesis has been investigated. The deviation from the average efficiency (4ċ9%) of three batches of colloid was at most 3ċ2%. These results prove that complete device manufacturing of nc‐DSC by a baseline process, starting with colloid synthesis is reproducible for surfaces up to 10×10 cm². Copyright © 2003 John Wiley & Sons, Ltd.