A new nitrate continuous observation sensor for autonomous sub-surface applications: Technical design and first results

Nitrate as one of the chemical parameters of major interest in marine biogeochemistry is detectable by means of its optical absorption in the ultra violet spectrum, given appropriate algorithms to correct for other seawater constituents. The presented work outlines the potential and technical requirements to adopt this new instrumentation in autonomous sub-surface applications. First results from laboratory experiment as well as from a flow-through application onboard RV POSEIDON cruise P347 in the North Atlantic are used to characterize the sensitivity of the method. Having long term deployment in mind, different antifouling strategies are reviewed and evaluated in the context of an optical sensor

Report and preliminary results of Victor Hensen cruise 96/1, Bremerhaven -Bremerhaven, 10.1. - 4.3.1996

SIGLEAvailable from TIB Hannover: RO 7630(96) / FIZ - Fachinformationszzentrum Karlsruhe / TIB - Technische InformationsbibliothekDEGerman

Ebbinghaus figures that deceive the eye do not necessarily deceive the hand

International audienceIn support of the visual stream dissociation hypothesis, which states that distinct visual streams serve vision-for-perception and vision-for-action, visual size illusions were reported over 20 years ago to `deceive the eye but not the hand'. Ever since, inconclusive results and contradictory interpretations have accumulated. Therefore, we investigated the effects of the Ebbinghaus figure on repetitive aiming movements with distinct dynamics. Participants performed a Fitts' task in which Ebbinghaus figures served as targets. We systematically varied the three parameters which have been shown to influence the perceived size of the Ebbinghaus figure's target circle, namely the size of the target, its distance to the context circles and the size of the context circles. This paper shows that movement is significantly affected by the context size, but, in contrast to perception, not by the other two parameters. This is especially prominent in the approach phase of the movement towards the target, regardless of the dynamics. To reconcile the findings, we argue that different informational variables are used for size perception and the visual control of movements irrespective of whether certain variables induce (perceptual) illusions