Unstable, self-limiting thermochemical temperature oscillations in Macrozamia cycads

Field measurements and laboratory experiments on the Australian cycads Macrozamia lucida and Macrozamia macleayi demonstrate that their cones' diel peak thermogenic temperature increase varies systematically with cone stage, with single thermogenic temperature peaks occurring daily for up to 2 weeks and reaching 12°C above ambient at midstage. The initiation, magnitude and timing of those peaks are strongly modulated by ambient temperature; the period between successive thermogenic temperature peaks is not circadian, and light is neither necessary nor sufficient to initiate a thermogenic event. A mathematical analysis is developed that provides a unified explanation of the experimental results. It describes these unstable, self-limiting thermogenic events in terms of conservation of energy and a first-order chemical reaction rate model that includes an Arrhenius equation dependence of the cone's metabolic heating rate on the cone temperature

A Case Study from an Emergency Operation in the Arctic Seas

The objective of this paper is to highlight the needs for improved access to high quality maritime data and information in the Arctic, and the need to develop maritime communication infrastructure with at least the same quality, in terms of availability and integrity, as in other more centralized areas. The foreseen Arctic ice meltdown is expected to provide new maritime transport corridors within relatively short time, and there is an urgent need to prepare for this, to ensure safe operations at sea and to protect the vulnerable Arctic environment. This paper points out some of these needs by presenting a case from a former accident in the Arctic sea. The case shows how the lack of proper information and data complicates the emergency operation. Some possible solutions to the challenges are proposed, and finally the paper briefly discusses the IMO e-Navigation concept in light of the Arctic challenges