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In this paper a classification and a survey of recent long-wave theories are presented. According to the basic variable of each approach, real-economic, monetary-financial, and social structure theories can be discerned. The inductive research is concentrated round the generalization of logistic growth paths borrowed from natural science, and the traditional but perhaps more preferable descriptive statistical methods for treating historical time series. The more deductive research is the most expansive field, and four directions can be found in it. The historical-institutional approach of Freeman and his SPRU group considers essentially the diffusion of the microelectronics technology complex as the most important challenge for the world economy. The growth-theoretical approach, starting with Mensch's publications, deals more with the analysis of unstable growth paths originating from technological basic innovations. The system dynamics model simulation of Forrester and his MIT group accentuates the rational behavior of microeconomic agents resulting in macroeconomic instability, caused by a self-ordering mechanism. In this context, monetary and financial variables seem to be important amplifiers of that instability. Finally, the influence of extraeconomic variables is an important debating theme. Indeed, fundamental technological change leads to institutional innovations on a national but most of all on an international level, and this leaves ample room for economic policy.

The opening sentences in the IIASA Charter speak about the problems generated by industrialization. Therefore industry, technology, and the economy have been implicitly or explicitly embodied in most of the Institute's projects. The first big IIASA research program, on energy, naturally entailed studying the impacts and dynamics of technology diffusion. This was the first research at the Institute to touch on the possible causes of long-term economic growth. Later studies of the management of innovation acknowledged the need to understand the interaction of technological with economic (and social) development beyond the frame of classical and neoclassical economics. One particular question reflected that need: How could cyclical influences be distinguished from structural ones? We tried to gain a better view by doing some case studies, which only increased our conviction that examination of these issues promised to be rewarding. The small meeting on long waves that we started to arrange eventually developed into a conference. The way the conference was organized and the cooperation it engendered further demonstrated that studies of these issues are timely. The problem that the organizers had to face was how to make maximum use of all the creative potential of the participants. It was therefore decided to arrange the conference in the following way: -- Full papers describing results of research on long waves were distributed before the conference and not read to the audience. -- Position papers on particular topics were selected before the conference so as to focus attention on the most important issues; the ensuing discussions and comments captured interesting views and ideas, reflecting the creative atmosphere of the meeting. This proceedings volume is structured accordingly: Parts I and II consist of a selection of the papers and comments on the five topics, and Part III includes further discussion by various participants. Part I starts with J. Delbeke's paper which gives an overview of the conference. This paper is particularly useful for those who are making a first acquaintance with this topic. We were also fortunate that several complete models or position papers on different long-wave schools were submitted to us. To keep the proceedings volume to a manageable and economic length, we were obliged to publish several of the papers submitted (by A. Piatier, A. Kleinknecht, J. Sterman, and J. Delbeke) separately as IIASA Collaborative Papers. We feel that this strikes a sensible middle course between the need to document the conference's work and the dictates of size and finance. The presence of leading representatives of different theories of long waves made it possible to gain first-hand insight into the state of the art, as well as to hear about the more promising directions for further research. Most meetings on long waves tend to be exclusively economy oriented, but the Siena/Florence meeting was rather different. Consistent with IIASA's interdisciplinary role, representatives of other disciplines were present and it is worth recording that researchers working in biology, demography and sociology hinted, in their contributions, at mechanisms studied in their own disciplines that could also lead to long-wave phenomena. In spite of the fact that many economists do not accept the existence of long waves as proven, the majority of scientists at the meeting did not question the existence or relevance of long-wave phenomena, irrespective of their cause. Nevertheless, it is extremely difficult to identify long-wave phenomena and several participants mentioned the problems to be expected in such investigations. IIASA and IRPET both focus on policy orientation and policy instruments. Proponents of all the theories represented were united in the idea that numerous phenomena could be better understood by applying long-wave theories. This understanding is essential for the design of optimal policies; therefore it appears that future research into long-wave issues is both desirable and necessary. We were very fortunate to have the support of our Italian hosts at an early stage in the development, preparation and organization the Conference. It is also to their credit that the meeting surpassed all expectations as far as scientific coverage of the topics and international representation was concerned, and we owe them our thanks for their warmth and generosity. Finally, the meeting in Siena and Florence was exceptional, both in that its scope was wide and that it integrated the work of researchers from East and West.

While the effects of early visual deprivation on auditory and tactile functions have been widely studied, little is known about olfactory function in early blind subjects. The present study investigated the potential effect of early blindness on the electrophysiological correlates of passive odour perception. Event-related potentials (ERPs) were recorded in eight early blind humans and eight sighted controls matched for age, sex and handedness during olfactory stimulation with 2-phenyl ethyl alcohol and trigeminal stimulation with CO2 Latencies, amplitudes and topographical distributions were analysed. As expected, the olfactory and trigeminal ERP components showed normal latencies, amplitudes and topography in both groups. Olfactory stimuli generated responses of smaller amplitude than those observed in response to trigeminal stimulation. In addition, ERP analyses did not reveal any major difference in electrocortical responses in occipital areas in early blind and sighted subjects. These results suggest that passive olfactory and trigeminal stimulation elicit the same electrophysiological responses in both groups, confirming that the neurophysiological correlates of the cross-modal compensatory mechanisms in early blind subjects do not appear during passive olfactory and trigeminal perception.