Granular YBaCuO films prepared by metalorganic chemical aerosol deposition technology

Fine-grain thin superconducting films can be prepared by metalorganic Chemical Aerosol Deposition Technology (CADT). In this paper, we present the preparation and properties of YBa2Cu3O7-x films on the different substrates, Si and SrTiO3 (100). It is shown that the zero-resistance temperature (Tc,0) of the films on SrTiO3 substrates is about 90 K, and the critical current density (Jc) at 77 K is above 104 A/cm2. In addition, these films exhibit significant grain-boundary weak link behaviour, which is very promising for applications in electronic devices

Tidal Heating of Extra-Solar Planets

Extra-solar planets close to their host stars have likely undergone significant tidal evolution since the time of their formation. Tides probably dominated their orbital evolution once the dust and gas had cleared away, and as the orbits evolved there was substantial tidal heating within the planets. The tidal heating history of each planet may have contributed significantly to the thermal budget that governed the planet's physical properties, including its radius, which in many cases may be measured by observing transit events. Typically, tidal heating increases as a planet moves inward toward its star and then decreases as its orbit circularizes. Here we compute the plausible heating histories for several planets with measured radii, using the same tidal parameters for the star and planet that had been shown to reconcile the eccentricity distribution of close-in planets with other extra-solar planets. Several planets are discussed, including for example HD 209458 b, which may have undergone substantial tidal heating during the past billion years, perhaps enough to explain its large measured radius. Our models also show that GJ 876 d may have experienced tremendous heating and is probably not a solid, rocky planet. Theoretical models should include the role of tidal heating, which is large, but time-varying.Comment: Accepted for publication to Ap

Planaire optische versterkers

Langs een glasfiber kan in de vorm van optische pulsjes verschrikkelijk veel informatie worden verzonden: de fiber heeft een zeer hoge transmissiecapaciteit. Wanneer echter voor het schakelen van de informatiestroom, of voor het regenereren van de pulsjes, de informatiestroom naar het elektrische domein omgezet moet worden en vice versa, geeft dit een enorme verlaging van deze capaciteit. Door drie Nederlandse groepen, wordt gedeeltelijk onder de paraplu van het IOP onderzoek gedaan aan een speciale klasse van planaire versterkers: nl die waarin de versterking berust op eigenschappen van zeldzame aard ionen zoals het Erbium-ion. En over dit onderzoek gaat dit artikel

Birefringence compensation in double-core optical waveguides

A new concept for birefringence compensation in planar optical waveguides applying a double-core structure is introduced. It is demonstrated on waveguides fabricated in silicon oxynitride technology for applications in optical telecommunicatio

Evaluation of the Gosnells Women's Health Service Healthy Lifestyles for Multicultural Women Program

In 2008 the Gosnells Women's Health Service (GWHS) was the recipient of a Healthy Active Australia grant. The aim of the grant was to increase the physicalactivity levels and healthy eating knowledge and behaviours of migrant women who access the GWHS. To achieve this aim the GWHS implemented learning activities for the target group, with the intention of increasing knowledge and changing behaviours for physical activity and nutrition. The physical activity component of the grant was implemented through swimming lessons and gentle exercise classes. Cooking and nutrition classes were held to teach the women about healthy and affordable foods.The swimming program attracted 118 participants, and 56 women participated in the gentle exercise sessions. The program increased most participants' physical activity levels by providing an opportunity to be active, as most women in the target group were not able to engage in physical activity for several reasons.The main barriers to physical activity in this group are a lack of affordable culturally appropriate (women's only) venues, and a lack of affordable child care. GWHS overcame these barriers by providing women's only activities and childcare. Twenty-seven women attended the cooking and nutrition classes. The classes increased women's knowledge of healthy and affordable foods which are available in Australia. The classes also assisted women, for whom English is a second language, with reading recipes. Nearly all participants who participated in evaluation reported cooking healthy meals at home for their families on completion of the sessions, and agreed that the sessions had increased their ability to do so. As a result of the program, the aquatic centre where the swimming lessons were held has agreed to continue running women's-only classes for those women who can attend the centre and pay for lessons

Tolerance and application of polarization independent waveguide for communication devices

A polarization independent optical waveguide structure has been developed and optimized towards minimized dependence on deviations in the processing parameters and very low processing complexity. The tolerance analysis was based on typical parameters of the silicon oxynitride technology. The optimized waveguide structure meets the criterion of a channel birefringence within 5x10-5 taking the processing tolerance into account. Moreover, it was found that the channel birefringence is thickness independent (within the 10-5 criterion) over a range of up to 200 nm. The optimized waveguide, fulfilling also the remaining demands of the application, has been applied for the realization of a passband flattened add-drop multiplexing device with 0.4 nm free spectral range and 0.03 nm TE-TM shift

A spot-size transformer for fiber-chip coupling in sensor applications at 633 nm in silicon oxynitride

A mode-size adapter was designed, fabricated in SiON/SiO2 and tested. It consists of a laterally tapered SiON waveguide having a step-wise decrease in thickness towards the taper point which may have up to 0.5 ¿m residual widt

Evaluation of polymer based third order nonlinear integrated optics devices

Nonlinear polymers are promising materials for high speed active integrated optics devices. In this paper we evaluate the perspectives polymer based nonlinear optical devices can offer. Special attention is directed to the materials aspects. In our experimental work we applied mainly Akzo Nobel DANS side-chain polymer that exhibits large second and third order coefficients. This material has been characterized by third harmonic generation, z-scan and pump-probe measurements. In addition, various waveguiding structures have been used to measure the nonlinear absorption (two photon absorption) on a ps time-scale. Finally an integrated optics Mach-Zehnder interferometer has been realized and evaluated. It is shown that the DANS side-chain polymer has many of the desired properties: the material is easily processable in high-quality optical waveguiding structures, has low linear absorption and its nonlinearity has a pure electronic origin. More materials research has to be done to arrive at materials with higher nonlinear coefficients to allow switching at moderate light intensity (< 1 W peak power) and also with lower nonlinear absorption coefficients

New insights on the relative sea level change during Holocene along the coasts of Tunisia and western Libya from archaeological and geomorphological markers

New data of sea level changes for the Mediterranean region along the coasts of northern Africa are presented. Data are inferred from archaeological sites of Punic-Roman age located along the coast of Tunisia, between Tunis and Jerba island and along the western coast of Libya, between Sabratha and Leptis Magna. Data are based on precise measures of presently submerged archaeological markers that are good indicators of past sea-level elevation. Nineteen selected archaeological sites were studied in Tunisia and four in Libya, all aged between w2.0 and w1.5 ka BP. The functional elevations of significant archaeological markers were measured with respect to the sea level at the time of measurements, applying corrections for tide and atmospheric pressure values. The functional elevations of specific architectural parts of the sites were interpreted, related to sea level at the time of their construction providing data on the relative changes between land and sea. Observations were compared against sea level change predictions derived from the glacio-hydro-isostatic model associated with the Last Glacial cycle. The results indicate that local relative sea level change along the coast of Tunisia and Libya, has increased 0.2 O 0.5 m since the last w2 ka. Besides minor vertical tectonic movements of the land, the observed changes are produced by eustatic and glacio-hydro-isostatic variations acting in the Mediterranean basin since the end of the last glacial maximum