Key building blocks for high-capacity WDM photonic transportnetworks

The objective of this paper is to give an overview of the different studies we have performed at the research level regarding the design and implementation of a photonic wavelength division multiplexing (WDM) layer providing transparent transport services to client layers (SONET/SDH, ATM, etc.). Such a network requires a number of enabling factors to be assessed in order to become a reality. Among these factors are the availability of high-capacity WDM transmission systems and efficient optical routing nodes based on mature technology, the design of robust networks optimizing the utilization of resources, and the development of a management system in accordance with presently applied standards for transport networks. We review our achievements in these different fields     

Optimisation of Tetrahydroisoquinoline‐Based Chimeric Microtubule Disruptors

Tetrahydroisoquinoline (THIQ)‐based “chimeric” microtubule disruptors were optimised through modification of the N‐benzyl motif, in concert with changes at C3 and C7, resulting in the identification of compounds with improved in vitro antiproliferative activities (e.g. 15 : GI₅₀ 20 nM in DU‐145). The broad anticancer activity of these novel structures was confirmed in the NCI 60‐cell line assay, with 12 e , f displaying MGM values in the 40 nM region. In addition, their profiles as inhibitors of tubulin polymerisation and colchicine binding to tubulin were confirmed. Compound 15 , for example, inhibited tubulin polymerisation with an IC₅₀ of 1.8 μM , close to that of the clinical drug combretastatin A‐4, and also proved effective at blocking colchicine binding. Additionally, compound 20 b was identified as the only phenol in the series to date showing both better in vitro antiproliferative properties than its corresponding sulfamate and excellent antitubulin data (IC₅₀=1.6 μM ). Compound 12 f was selected for in vivo evaluation at the NCI in the hollow fibre assay and showed very good activity and wide tissue distribution, illustrating the value of this template for further development.     

Tetrahydroisoquinolinone‐Based Steroidomimetic and Chimeric Microtubule Disruptors

A structure–activity relationship (SAR) translation strategy was used for the discovery of tetrahydroisoquinoline (THIQ)‐based steroidomimetic and chimeric microtubule disruptors based upon a steroidal starting point. A steroid A,B‐ring‐mimicking THIQ core was connected to methoxyaryl D‐ring ring mimics through methylene, carbonyl and sulfonyl linkers to afford a number of steroidomimetic hits (e.g., 7‐methoxy‐2‐(3‐ methoxybenzyl)‐6‐sulfamoyloxy‐1,2,3,4‐tetrahydroisoquinoline ( 20 c ) GI₅₀=2.1 μM ). Optimisation and control experiments demonstrate the complementary SAR of this series and the steroid derivatives that inspired its design. Linkage of the THIQ‐based A,B‐mimic with the trimethoxyaryl motif prevalent in colchicine site binding microtubule disruptors delivered a series of chimeric molecules whose activity (GI₅₀=40 nM ) surpasses that of the parent steroid derivatives. Validation of this strategy was obtained from the excellent oral activity of 7‐methoxy‐6‐sulfamoyloxy‐2‐(3,4,5‐trimethoxybenzyl)‐1,2,3,4‐tetrahydroisoquinoline ( 20 z ) relative to a benchmark steroidal bis‐ sulfamate in an in vivo model of multiple myeloma.     

Polycrystalline microstructure, cubic elasticity, and nucleation of high-cycle fatigue cracks

It is well-known that high-cycle fatigue cracks usually nucleate in surface well-oriented grains with a high Schmid factor. A numerical evaluation of the effect of crystalline elasticity anisotropy (which is often neglected) on the stress state in well-oriented grains is presented. Each of these grains is located at the free surface of an aggregate. The other crystallographic orientations are random. Numerous finite element computations are carried out for evaluating the effect of the neighboring grain orientations. Resolved shear stress and normal stress averages are given, as well as scatter parameters and histograms. Several metals, orientations, and loading conditions are considered. For common (anisotropic) metals/alloys such as copper and austenitic steels, the local average resolved shear stress is about 18% smaller than the macroscopic value which induces a Schmid factor value with respect to the macroscopic tensile stress of 0.41 instead of the classical 0.5 value. Relative scatters in resolved shear stress and corresponding normal stress are high (respectively ± 22% and ± 38%). These high scatter values computed for small applied loads can explain many observations taken from the literature showing a large scatter in the plastic slip line feature, dislocation microstructure, microstructurally short crack nucleation, and propagation rate among well-oriented surface grains. Finally, the effects of some geometrical parameters are evaluated (2D/3D effects, subsurface grains....).     

High performance optical wavelength shifter

A broadband (>50 nm) wavelength shifter capable of switching multigigabit data between optical frequencies in the 1.5 mu m region is presented. The device, based on gain saturation in a semiconductor optical amplifier, is tunable, has gain, and is nearly polarisation insensitive. Data degradation after wavelength shifting is negligible.<>     

In vitro induction of apoptosis or differentiation by dopamine in an immortalized olfactory neuronal cell line

A new neuronal cell line was generated by transfection of rat olfactory epithelium with immortalizing recombinant oncogene E1A of adenovirus-2. The resulting 13.S.1.24 line of transformed cells expressed an antigenic phenotype of olfactory neuronal progenitors. Addition of dopamine to 13.S.1.24 cultures induced reduction of cell number within 2 days. Two hallmarks of apoptosis were detected in dopamine-treated cultures: internucleosomal DNA fragmentation and nuclear condensation. Dopamine did not alter the cell proliferation rate, as assessed by [3H]thymidine incorporation. Dopamine also stimulated differentiation of surviving 13.S.1.24 cells into bipolar olfactory marker protein-immunoreactive neurons. Time-dependency assessments over 1 week of treatment indicated that apoptosis and differentiation induced by dopamine were concomitant. Both apoptosis and differentiation triggered by dopamine were dose-dependent, half-maximal effects being obtained with approximately 10 microM dopamine. Mediation of both effects by dopaminergic D2 receptors was supported by several observations: active dopamine doses in micromolar ranges, quinpirole agonism and eticlopride antagonism, D2-characteristic rank order of potency among the three agonists tested, and specific binding of a selective D2-like radioligand to 13.S.1.24 cells. The present data altogether indicated that dopamine commits immortalized olfactory neuronal cells in vitro either to apoptosis or to olfactory-like differentiation via D2 dopaminergic receptors.     

A target for precise Møller polarimetry

In order to achieve better accuracy on the measurement of electron beam polarization employing - scattering, we have developed an improved polarized electron target. Using a pure iron foil saturated out-of-plane in a 4 T magnetic field one can reduce the systematical errors to the promille level. Measurement of the relative target polarization using polarized light and the Kerr effect allows to observe on-line the change in target polarization due to heating by the electron beam.     

Pan-European optical networking using wavelength divisionmultiplexing

The development of the information society will require the introduction of high-capacity transport networks with high performance and low cost. There are currently two ACTS (Advanced Communications Technologies and Services program launched by the European Commission) projects addressing specifically the problem of trans-European optical transport networks using WDM (wavelength division multiplexing). Important issues addressed are the high capacity transmission on existing fiber infrastructure and the introduction of flexibility in the network through the use of optical cross-connects. If these networks become a reality, they could drastically change the evolution of both telecommunication and computer networking because of their transparency and the abundance of inexpensive bandwidth     

Generating Stochastic Wall Patterns On‐the‐fly with Wang Tiles

The game and movie industries always face the challenge of reproducing materials. This problem is tackled by combining illumination models and various textures (painted or procedural patterns). Generating stochastic wall patterns is crucial in the creation of a wide range of backgrounds (castles, temples, ruins…). A specific Wang tile set was introduced previously to tackle this problem, in an iterative fashion. However, long lines may appear as visual artifacts. We use this tile set in a new on‐the‐fly procedure to generate stochastic wall patterns. For this purpose, we introduce specific hash functions implementing a constrained Wang tiling. This technique makes possible the generation of boundless textures while giving control over the maximum line length. The algorithm is simple and easy to implement, and the wall structure we get from the tiles allows to achieve visuals that reproduce all the small details of artist painted walls.     

Formation of Boron‐doped region using spin‐on dopant: investigation on the impact of metallic impurities

Investigation on the electrical properties of p⁺‐doped regions formed by spin‐on‐dopant (SOD) technique was achieved. Using this technique, boron‐diffused regions were formed on both p‐type and n‐type float zone wafers. Homogeneous sheet resistances were obtained for both types of wafers. Bulk properties were investigated by measuring effective carrier lifetime. An iron contamination was observed after the boron diffusion step and interstitial iron concentrations were deduced from lifetime measurements. More investigations proved that the iron was initially present within the SOD film. A phosphorus diffusion allows to remove this bulk contamination, leading to an improvement of effective lifetime values. Nevertheless, the corresponding emitter saturation current density was estimated on n‐type wafers and presented a high value. It is likely that this poor electrical quality is the consequence of a high iron concentration which remains in the diffused region. Some possibilities are suggested to avoid or to limit this contamination. Copyright © 2008 John Wiley & Sons, Ltd.