Daisyworld: a review

Daisyworld is a simple planetary model designed to show the long-term effects of coupling between life and its environment. Its original form was introduced by James Lovelock as a defense against criticism that his Gaia theory of the Earth as a self-regulating homeostatic system requires teleological control rather than being an emergent property. The central premise, that living organisms can have major effects on the climate system, is no longer controversial. The Daisyworld model has attracted considerable interest from the scientific community and has now established itself as a model independent of, but still related to, the Gaia theory. Used widely as both a teaching tool and as a basis for more complex studies of feedback systems, it has also become an important paradigm for the understanding of the role of biotic components when modeling the Earth system. This paper collects the accumulated knowledge from the study of Daisyworld and provides the reader with a concise account of its important properties. We emphasize the increasing amount of exact analytic work on Daisyworld and are able to bring together and summarize these results from different systems for the first time. We conclude by suggesting what a more general model of life-environment interaction should be based on

The Joint Influence of Intra- and Inter-Team Learning Processes on Team Performance: A Constructive or Destructive Combination?

In order for teams to build a shared conception of their task, team learning is crucial. Benefits of intra-team learning have been demonstrated in numerous studies. However, teams do not operate in a vacuum, and interact with their environment to execute their tasks. Our knowledge of the added value of inter-team learning (team learning with external parties) is limited. Do both types of team learning compete over limited resources, or do they form a synergistic combination? We aim to shed light on the interplay between intra- and inter-team learning in relation to team performance, by including adaptive and transformative sub-processes of intra-team learning. A quantitative field study was conducted among 108 university teacher teams. The joint influence of intra- and inter-team learning as well as structural (task interdependence) and cultural (team efficacy) team characteristics on self-perceived and externally rated team performance were explored in a path model. The results showed that adaptive intra-team learning positively influenced self-perceived team performance, while transformative intra-team learning positively influenced externally rated team performance. Moreover, intra-team and inter-team learning were found to be both a constructive and a destructive combination. Adaptive intra-team learning combined with inter-team learning led to increased team performance, while transformative intra-team learning combined with inter-team learning hurt team performance. The findings demonstrate the importance of distinguishing between both the scope (intra- vs. inter-team) and the level (adaptive vs. transformative) of team learning in understanding team performance

Responsive curriculum development for professional education: Different teams, different tales

Due to fast and unpredictable developments, professional education is challenged with being responsive, which demands a rethinking of conventional curriculum development approaches. Yet, literature on curriculum development falls short in terms of recognising how to react rapidly and adequately to these new developments. This study focuses on curriculum development initiatives at the school level in a Dutch university of applied sciences. Open interviews were held with 29 curriculum developers to explore how they define and give substance to developing curricula for new, changing or unpredictable professions. These 29 participants were involved in seven curriculum development trajectories. Four themes were detected: (1) curriculum developers are in favour of open, flexible and authentic curricula; (2) the context in which the curriculum development takes place and the different roles and responsibilities of curriculum developers are challenging; (3) curriculum developers feel insufficiently equipped to carry out their tasks; and (4) involving stakeholders is necessary but results in a “viscous” social–political process. Responsive curriculum development requires a great deal of flexibility and adaptability from curriculum developers. Yet, in our study, “institutional concrete” is found to severely hinder responsive curriculum development processes. To be responsive, such processes need to be supported and institutional barriers need to be removed

An investigation of switching and conduction losses in inverters under varying inductor ripple current

This paper presents an accurate method of calculating the switching device losses in a half bridge DC-AC inverter. The analysis is based on an existing numerical method of calculating the inductor ripple current. The losses are calculated by replicating the exact current waveform flowing through the switching devices. This method allows for a more accurate loss calculation than the well-known existing analytical methods. The different methods are discussed and the results are compared. © 2009 IEEE.Conference Pape