Miniature packaged actively mode-locked semiconductor laser with tunable 20 ps transform limited pulses

Miniature, fibre tailed and packaged, wavelength tunable actively mode locked semiconductor lasers have been developed for use as sources of approximately 20 ps transform limited pulses. Continuous stable operation with >40 nm tuning ranges centred either at 1.3 mu m or 1.55 mu m have been demonstrated. The package has an adjustable cavity length enabling the repetition frequency to be selected between 2 GHz and 8 GHz. Mean output powers in the monomode fibre tail are in the range -10 dBm to -5 dBm.<>     

565 Mbit/s 219 km transmission experiment using four gain controlled packaged semiconductor laser amplifiers

A 565 Mbit/s 219 km optical transmission system is investigated, using four gain controlled travelling wave semiconductor laser amplifier packages. The addition of gain control caused little deterioration in system performance, and allowed stable operation against changes in signal polarisation and device temperature. Residual system output power fluctuations of less than 0.5 dB were observed over a 7 degree temperature range.<>     

Conservative Polarimetric Scatterers and Their Role in Incorrect Extensions of the Cameron Decomposition

The properties of conservative symmetric polarimetric scatterer scattering matrices are examined. It is shown that the unambiguous rotation angle for "conservative" symmetric polarimetric scatterers is the interval (-pi/4,+pi/4] as compared with (-pi/2,+pi/2] for nonconservative symmetric scatterers. Errors relating to the Cameron decomposition, which are recently introduced into the literature, are discussed. It is demonstrated that these errors arise from a faulty symmetric scatterer scattering matrix distance measure. This, in turn, leads to an improper mapping of the symmetric scatterer unit disk to a hemisphere. The correct mapping of the symmetric scatterer unit disk to the symmetric scatterer unit sphere is described     

Advancing Equity in Clinical Preventive Services: The Role of Health Communication

In 2002, the Institute of Medicine released its landmark report “Unequal Treatment: Confronting Racial and Ethnic Disparities in Health Care.” This report led to increased efforts in identifying, assessing, and documenting racial and ethnic disparities in health care, as well as developing, testing, and implementing interventions in an attempt to reduce health disparities throughout the United States. This article reviews the rise of health disparities research in the United States and reports on selected studies and interventions developed by researchers at the Northwestern University Feinberg School of Medicine. These interventions have used communication and behavioral science theories and frameworks in their development and dissemination, particularly in the realm of clinical preventive medicine.     

Functional Porous Polymers by Emulsion Templating: Recent Advances

Porous materials are currently of great scientific as well as technological interest. A strategy that is increasingly employed to prepare highly porous and well defined macroporous polymers is emulsion templating, whereby the droplets of a high internal phase emulsion are used to create pores in a solid material by curing or polymerization of the emulsion continuous phase. This Feature Article covers recent work in this area, focusing on: the preparation of such materials from new precursors and via novel approaches; the chemical modification of existing materials; and the application of the resulting porous structures in diverse areas of science and technology.     

Evaluation of Brassica species as leaf sources for extending the processing season of a leaf protein concentrate plant

Leaf protein concentrates (LPC) were prepared in large pilot plant equipment from seven Brassica varieties grown on plots of up to 0.06 ha. Plants were harvested about a month before and after the lucerne processing season. Best yields of LPC, from leafier or forage-type species, were up to 0.9 t ha^?1. Properties were as good as or better than those of LPC from lucerne. Lucerne processing procedures were modified to maximize yields from the more succulent Brassica plants.     

Modulation of Mechanical Interactions by Local Piezoelectric Effects

Piezoelectricity is a well‐established property of biological materials, yet its functional role has remained unclear. Here, a mechanical effect of piezoelectric domains resulting from collagen fibril organisation is demonstrated, and its role in tissue function and application to material design is described. Using a combination of scanning probe and nonlinear optical microscopy, a hierarchical structuring of piezoelectric domains in collagen‐rich tissues is observed, and their mechanical effects are explored in silico. Local electrostatic attraction and repulsion due to shear piezoelectricity in these domains modulate fibril interactions from the tens of nanometre (single fibril interactions) to the tens of micron (fibre interactions) level, analogous to modulated friction effects. The manipulation of domain size and organisation thus provides a capacity to tune energy storage, dissipation, stiffness, and damage resistance.     

A mechanism of fluid replenishment in elastohydrodynamic contacts

The use of aerated oil has enabled observation of the direction of flow around an elastohydrodynamic contact formed between a glass plate and steel ball. Replenishment of the inlet region from lubricant side bands was seen to occur within the inlet meniscus. The balance between the rate at which oil is entrained and the rate at which it is lost around the contact edges determines the inlet boundary position. Similar replenishment action has also been observed to occur in line contact using blended rollers.     

Linking Glass-Transition Behavior to Photophysical and Charge Transport Properties of High-Mobility Conjugated Polymers

The measurement of the mechanical properties of conjugated polymers can reveal highly relevant information linking optoelectronic properties to underlying microstructures and the knowledge of the glass transition temperature (T_g) is paramount for informing the choice of processing conditions and for interpreting the thermal stability of devices. In this work, we use dynamical mechanical analysis to determine the T_g of a range of state-of-the-art conjugated polymers with different degrees of crystallinity that are widely studied for applications in organic field-effect transistors. We compare our measured values for T_g to the theoretical value predicted by a recent work based on the concept of effective mobility ζ. The comparison shows that for conjugated polymers with a modest length of the monomer units, the T_g values agree well with theoretically predictions. However, for the near-amorphous, indacenodithiophene–benzothiadiazole family of polymers with more extended backbone units, values for T_g appear to be significantly higher, predicted by theory. However, values for T_g are correlated with the sub-bandgap optical absorption suggesting the possible role of the interchain short contacts within materials’ amorphous domains.