Asymptotically flat spacetimes in 3D bigravity

We report that a class of three-dimensional bimetric theories contain asymptotically flat solutions. These spacetimes can be cast in a set of asymptotic conditions at null infinity which are preserved under the infinite dimensional BMS group. Moreover, the algebra of the canonical generators exhibits a central extension. The possibility that these solutions describe regular black holes is also discussed.Comment: 6 page

Boundary dynamics of asymptotically flat 3D gravity coupled to higher spin fields

We construct a two-dimensional action principle invariant under a spin-three extension of BMS$_3$ group. Such a theory is obtained through a reduction of Chern-Simons action with a boundary. This procedure is carried out by imposing a set of boundary conditions obtained from asymptotically flat spacetimes in three dimensions. When implementing part of this set, we obtain an analog of chiral WZW model based on a contraction of $sl(3,\mathbb{R}) \times sl(3,\mathbb{R})$. The remaining part of the boundary conditions imposes constraints on the conserved currents of the model, which allows to further reduce the action principle. It is shown that a sector of this latter theory is related to a flat limit of Toda theory.Comment: 16 pages, no figure

Artistic creation and intellectual property

We analyze artistic markets considering three key distinctive features that have been overlooked by the standard analysis on intellectual property. These features are the dynamic link between the current number of young artists and future high-quality artistic creation, Rosen's superstars phenomenon, and the role played by promotion costs. Introducing them into an overlapping-generations model brings about a new perspective on the consequences for artistic creation of changes in the copyright term, progress in communication technologies favoring market concentration by stars, and the enlargement of markets. The conventional result that longer copyrights always stimulate artistic creation only holds as a particular case

Artistic creation and intellectual property

We analyze artistic markets considering three key distinctive features that have been overlooked by the standard analysis on intellectual property. These features are the dynamic link between the current number of young artists and future high-quality artistic creation, Rosen's superstars phenomenon, and the role played by promotion costs. Introducing them into an overlapping-generations model brings about a new perspective on the consequences for artistic creation of changes in the copyright term, progress in communication technologies favoring market concentration by stars, and the enlargement of markets. The conventional result that longer copyrights always stimulate artistic creation only holds as a particular case.superstars; copyright; innate abilities; talent

Linear Stability Analysis for Plane-Poiseuille Flow of an Elastoviscoplastic fluid with internal microstructure

We study the linear stability of Plane Poiseuille flow of an elastoviscoplastic fluid using a revised version of the model proposed by Putz and Burghelea (Rheol. Acta (2009)48:673-689). The evolution of the microstructure upon a gradual increase of the external forcing is governed by a structural variable (the concentration of solid material elements) which decays smoothly from unity to zero as the stresses are gradually increased beyond the yield point. Stability results are in close conformity with the ones of a pseudo-plastic fluid. Destabilizing effects are related to the presence of an intermediate transition zone where elastic solid elements coexist with fluid elements. This region brings an elastic contribution which does modify the stability of the flow

Sustainable management: a strategic challenge for a global minerals and metals industry

This paper refers to the concept of sustainable management as the management approach which efficiently integrates economic, environmental and social issues into the operations of the minerals and metals industries, with the aim of creating long-term benefits for all stakeholders, and securing the support, cooperation, and trust of the local community. Among many other issues, sustainable management deals with strategy, responsible project feasibility decisions, managing for operational efficiency, improved risk management, enhanced stakeholder relationships, and corporate reputation. Overall, it deals with seeking long-term competitive advantages through responsible management of environmental and social issues. An essential requirement for sustainable management is the corporate commitment to the values of sustainability, but this is not sufficient. Also essential is the development of a business culture where sustainability is a high professional and business value. Furthermore, an organizational structure with specific roles and integration mechanisms and adequate management systems are also required. Regarding business culture, a well-established business code is a necessary but an insufficient condition. Sustainable management relies on individual ethical conduct and trust to foster full participation of stakeholders and to encourage commitment among them. It allows decision making at appropriate levels in the organization and encourages individual risk-taking for continuous improvement. Without trust, social licence is not achievable. In this paper, the concept of sustainable management is introduced as the management approach that integrates a business culture, strong leadership and an organizational structure that strives for long term economics benefits through sustainability. To achieve this goal, sustainability must be vertically integrated at three organizational levels (corporate, divisional and operational) and three functional levels (strategy, planning and implementation)