Leonardo depicted America : misread as the moon

Leonardo da Vinci must have been aware that Columbus discovered new territories in the West. Until now, no material evidence had been found to substantiate this assumption. Here we show that Leonardo not only read Amerigo Vespucci’s letter (derived from a painted star constellation), but that he even drew a map including the New World, a drawing which was previously interpreted as a depiction of the Moon. Finally, Leonardo engraved his notion of this new continent on an ostrich egg globe (now known as the Da Vinci Globe) and made a copper cast of this. Both the cosmographic and cartographic clues demonstrate that Leonardo da Vinci knew about the fourth continent, to be named “America” in 1507, less than a decade after Columbus embarked upon its shores. This expansion of Leonardo’s cartographic legacy comes at a time of increased interest for such multi-disciplinary insights, as the world commemorates in 2019 the 500th anniversary of his death

Integration of stretchable optical waveguides with sources and detectors

This presentation explains why we should use flexible or stretchable waveguides and why we should integrate sources and detectors. Furthermore, the status of the ongoing research is detaile

Characterization of the modal parameters of composite laminates using innovative ultrathin polymer waveguide sensor foils

The use of composite materials, like glass- and carbon- fiber reinforced polymers, is expected to increase exponentially in the coming years. Consequently, in order to monitor the structural health of these materials, the development of new sensing devices is rapidly accelerating. For this purpose, our research groups have recently developed new ultra-thin polymer waveguide sensors which can be exploited to measure both uniaxial and multiaxial strains occurring in composite components. These sensing foils are manufactured by creating Bragg gratings in waveguides realized in flat polymeric substrates, which makes their placement and alignment easier compared to traditional fiber optic sensors. Moreover, using a non-straight waveguide it is possible to spatially multiplex the sensing gratings in such a way that an optical strain rosette can be created. This paper investigates the suitability of the proposed polymer waveguide sensors for the estimation of the modal parameters of composite components

Multimode PDMS waveguides fabricated using a hot-embossing technique

A novel method for fabricating multimode PDMS waveguides is presented. This process is based on a hot-embossing technique and generates high quality optical waveguides without a substantial residual layer after embossing. Furthermore, the process allows for low-cost fabrication since it relies on a replication technique and additionally only commercially available materials are used. The measured propagation loss is smaller than 0.24dB/cm and can be further reduced by improving the master mould quality

Flexible photonic sensors realized using printing technologies

Making sensors flexible and thin, is key to apply them on curved, moving surfaces, e.g. for wearable applications or to embed them in mechanical structures. Photonic sensor systems require the integration of microstructures (e.g. polymer waveguides), nanostructures (e.g. gratings), which can be realized using nanoimprint lithography, but may also need additional active or passive optical components, which can be integrated using laser printing technologies

Age differences in mammography screening reconsidered: life course trajectories in 13 European countries

Background: Breast cancer is the most common cause of cancer mortality among European women. To reduce mortality risk, early detection through mammography screening is recommended from the age of 50 years onwards. Although timely initiation is crucial for cancer prognosis, the temporal dimension has largely been ignored in research. In cross-sectional research designs, it is not clear whether reported age differences reflect ‘true’ age effects and/or presumed period effects resulting from evolving knowledge and screening programmes. Methods: We use longitudinal data from the survey of Health, Ageing and Retirement (SHARELIFE, 2008), which enables to cast light on age differences by providing retrospective information on the age at which women commenced regular mammography screening. Moreover, the cross-national dimension of the SHARE permits framing the results within the context of nationally implemented screening programmes. By means of the Kaplan–Meier procedure, we examine age trajectories for five 10-year birth cohorts in 13 European countries (n = 13 324). Results: Birth cohorts show very similar age trajectories for each country. Along with the observation that large country differences and country-specific deviations coincide with screening programme characteristics, this suggests strong period effects related to implemented national screening programmes. Conclusion: Age differences in mammography screening generally reflect the period effects of national screening policies. This leaves little room for economic theories about human health capital that leave out the institutional context of preventive health care provision