A multiplicative potential approach to solutions for cooperative TU-games

Concerning the solution theory for cooperative games with transferable utility, it is well-known that the Shapley value is the most appealing representative of the family of (not necessarily efficient) game-theoretic solutions with an additive potential representation. This paper introduces a new solution concept, called Multiplicativily Proportional ($MP$) value, that can be regarded as the counterpart of the Shapley value if the additive potential approach to the solution theory is replaced by a multiplicative potential approach in that the difference of two potential evaluations is replaced by its quotient. One out of two main equivalence theorems states that every solution with a multiplicative potential representation is equivalent to this specifically chosen efficient value in that the solution of the initial game coincides with the $MP$ value of an auxiliary game. The associated potential function turns out to be of a multiplicative form (instead of an additive form) with reference to the worth of all the coalitions. The second equivalence theorem presents four additional characterizations of solutions that admit a multiplicative potential representation, e.g., preservation of discrete ratios or path independence

Ethnic minority groups and social enterprise: a case study of the East London Olympic boroughs

The world has witnessed the emergence of a great number and variety of social entrepreneurial activities in recent years. In the United Kingdom, the SE sector has experienced considerable growth and nowadays is at the centre of academic and political debate. Yet, very little is known about the extent and nature of ethnic minority involvement in social enterprise activity. Critical to an understanding of this is the reduction of grant funding to third sector organisations as well as the change in race relations and equality policies. Moreover, the social enterprise political discourse that has seen social enterprises as an alternative to move towards market-led provision and the privatisation of public services is relevant to understand the development of ethnic minority social enterprise activities. This research produces insights into the nature and extent of ethnic minority social enterprise activities in the East London Olympic Boroughs and provides a fundamental contribution to the development of policy thinking. This thesis also contributes to theory building in the area through the development of a conceptual framework. Structuration and Mixed Embeddedness theories are considered to explain how the development of ethnic minority social entrepreneurial activities depends on the complex interaction between ethnic minority entrepreneurs (as agents) and the context (as structures) in which they are embedded. This research draws upon evidence from a case study in the East London Olympic Boroughs using a mixed-methods approach, which includes literature and policy review, telephone survey, semi-structured interviews and an in-depth study of organisations. Through analysis of the case study, what is discovered is that there are challenges in defining and measuring ethnic minority social enterprise activities. This thesis also reveals that the role of individual ethnic minority entrepreneurs is crucial for the development of social enterprise activities as well as the context in which they are embedded in terms of their access to resources, market opportunities and the political context that determines this development. Finally, findings demonstrate that the current policy discourse provides little scope for engagement for the majority of small-scale ethnic minority social enterprise organisations

The Mirage of Exchange Rate Regimes for Emerging Market Countries

This paper argues that much of the debate on choosing an exchange rate regime misses the boat. It begins by discussing the standard theory of choice between exchange rate regimes, and then explores the weaknesses in this theory, especially when it is applied to emerging market economies. It then discusses a range of institutional traits that might predispose a country to favor either fixed or floating rates, and then turns to the converse question of whether the choice of exchange rate regime may favor the development of certain desirable institutional traits. The conclusion from the analysis is that the choice of exchange rate regime is likely to be of second order importance to the development of good fiscal, financial, and monetary institutions in producing macroeconomic success in emerging market countries. This suggests that less attention should be focused on the general question whether a floating or a fixed exchange rate is preferable, and more on these deeper institutional arrangements. A focus on institutional reforms rather than on the exchange rate regime may encourage emerging market countries to be healthier and less prone to the crises that we have seen in recent years.

A Statistical Study of Photospheric Magnetic Field Changes During 75 Solar Flares

Abrupt and permanent changes of photospheric magnetic fields have been observed during solar flares. The changes seem to be linked to the reconfiguration of magnetic fields, but their origin is still unclear. We carried out a statistical analysis of permanent line-of-sight magnetic field ($B_{\rm LOS}$) changes during 18 X-, 37 M-, 19 C- and 1 B-class flares using data from Solar Dynamics Observatory/Helioseismic and Magnetic Imager. We investigated the properties of permanent changes, such as frequency, areas, and locations. We detected changes of $B_{\rm LOS}$ in 59/75 flares. We find that strong flares are more likely to show changes, with all flares $\ge$ M1.6 exhibiting them. For weaker flares, permanent changes are observed in 6/17 C-flares. 34.3\% of the permanent changes occurred in the penumbra and 18.9\% in the umbra. Parts of the penumbra appeared or disappeared in 23/75 flares. The area where permanent changes occur is larger for stronger flares. Strong flares also show a larger change of flux, but there is no dependence of the magnetic flux change on the heliocentric angle. The mean rate of change of flare-related magnetic field changes is 20.7 Mx cm$^{-2}$ min$^{-1}$. The number of permanent changes decays exponentially with distance from the polarity inversion line. The frequency of the strength of permanent changes decreases exponentially, and permanent changes up to 750 Mx cm$^{-2}$ were observed. We conclude that permanent magnetic field changes are a common phenomenon during flares, and future studies will clarify their relation to accelerated electrons, white light emission, and sunquakes to further investigate their origin.Comment: Piblished in Ap

Conducting video research in the social and solidarity economy: empowering the Cinderella economy towards social justice

This paper focuses on the potential use of visual research for the study of the social and solidarity economy, by presenting some of the methodological insights and challenges that arise for the use of video research in the study of such initiatives reflecting on the authors experience of the Living in Minca project. This paper contributes to advancing the debate on the use of non-conventional research methods and the impact that visual researchers can make by empowering small and local practices, which are part of the so-called ‘Cinderella' economy towards social justice and reaching audiences outside academia

Spatiotemporal instability of a confined capillary jet

Recent experimental studies on the instability appearance of capillary jets have revealed the capabilities of linear spatiotemporal instability analysis to predict the parametrical map where steady jetting or dripping takes place. In this work, we present an extensive analytical, numerical and experimental analysis of confined capillary jets extending previous studies. We propose an extended, accurate analytic model in the limit of low Reynolds flows, and introduce a numerical scheme to predict the system response when the liquid inertia is not negligible. Theoretical predictions show a remarkable accuracy with results from the extensive experimental exploration provided.Comment: Submitted to the Physical Review E (20-March-2008