On-line learning of unrealizable tasks

The dynamics of on-line learning is investigated for structurally unrealizable tasks in the context of two-layer neural networks with an arbitrary number of hidden neurons. Within a statistical mechanics framework, a closed set of differential equations describing the learning dynamics can be derived, for the general case of unrealizable isotropic tasks. In the asymptotic regime one can solve the dynamics analytically in the limit of large number of hidden neurons, providing an analytical expression for the residual generalization error, the optimal and critical asymptotic training parameters, and the corresponding prefactor of the generalization error decay.

A composite leading indicator of the inflation cycle for the Euro area

We evaluate the performance of composite leading indicators of turning points of inflation in the Euro area, constructed by combining the techniques of Fourier analysis and Kalman filters with the National Bureau of Economic Research methodology. In addition, the study compares the empirical performance of Euro Simple Sum and Divisia monetary aggregates and provides a tentative answer to the issue of whether or not the UK should join the Euro area. Our findings suggest that, first, the cyclical pattern of the different composite leading indicators very closely reflect that of the inflation cycle for the Euro area; second, the empirical performance of the Euro Divisia is better than its Simple Sum counterpart and third, the UK is better out of the Euro area. © 2005 Taylor & Francis Group Ltd.

Extrinsic factors in the perception of bistable motion stimuli

When viewing a drifting plaid stimulus, perceived motion alternates over time between coherent pattern motion and a transparent impression of the two component gratings. It is known that changing the intrinsic attributes of such patterns (e.g. speed, orientation and spatial frequency of components) can influence percept predominance. Here, we investigate the contribution of extrinsic factors to perception; specifically contextual motion and eye movements. In the first experiment, the percept most similar to the speed and direction of surround motion increased in dominance, implying a tuned integration process. This shift primarily involved an increase in dominance durations of the consistent percept. The second experiment measured eye movements under similar conditions. Saccades were not associated with perceptual transitions, though blink rate increased around the time of a switch. This indicates that saccades do not cause switches, yet saccades in a congruent direction might help to prolong a percept because i) more saccades were directionally congruent with the currently reported percept than expected by chance, and ii) when observers were asked to make deliberate eye movements along one motion axis, this increased percept reports in that direction. Overall, we find evidence that perception of bistable motion can be modulated by information from spatially adjacent regions, and changes to the retinal image caused by blinks and saccades.

"Marketing and flexibility":debates past present and future

Special issue editorial: Purpose – The purpose of this paper is to outline the articles presented in the Special Issue on the topic of “Marketing and flexibility”, and to discuss key issues associated with major debates relating to flexibility in order to position the articles within a wider context and highlight some key issues for further research. Design/methodology/approach – Themes in prior research relating to “Marketing and flexibility” are documented and the growth of research interest into strategic flexibility is tabulated. The contributions of each article are briefly discussed. Findings – There has been a steady growth of research interest into flexibility. To provide an example of this growth, the increase in the number of articles published on the topic of strategic flexibility in scholarly journals is highlighted over a 20-year period. Key issues in prior research such as alternative definitions and the different postulated relationships between market orientation and strategic flexibility are revealed, as are issues for future research. Originality/value – Key issues relating to research into flexibility for marketing scholars are revealed.

Reluctant donors? The Europeanization of international development policies in the New Member States

The European Union (EU) played an instrumental role in re-starting the international development policies in central and eastern European Member States, but questions remain about how far this policy area has been Europeanized since accession. Focusing on the Czech Republic, Hungary, Poland and Slovakia, this article investigates why the new donors have been reluctant to adopt the EU's development acquis more fully. The article traces the socialization processes offered by the EU's development policy rule-making and subsequent national rule implementation. The conclusions reveal three reasons why socialization has been weak: perceptions among the new Member States on the procedural legitimacy of the development acquis; low domestic resonance with the development acquis; and inconsistencies in the activities of norm entrepreneurs. The article contributes to our understanding of development policy in the EU – particularly how decision-making takes place within the Council and its working groups post-enlargement.