Equilibrium configurations of two charged masses in General Relativity

An asymptotically flat static solution of Einstein-Maxwell equations which describes the field of two non-extreme Reissner - Nordstr\"om sources in equilibrium is presented. It is expressed in terms of physical parameters of the sources (their masses, charges and separating distance). Very simple analytical forms were found for the solution as well as for the equilibrium condition which guarantees the absence of any struts on the symmetry axis. This condition shows that the equilibrium is not possible for two black holes or for two naked singularities. However, in the case when one of the sources is a black hole and another one is a naked singularity, the equilibrium is possible at some distance separating the sources. It is interesting that for appropriately chosen parameters even a Schwarzschild black hole together with a naked singularity can be "suspended" freely in the superposition of their fields.Comment: 4 pages; accepted for publication in Phys. Rev.

Governing the Global Land Grab: Multipolarity, Ideas and Complexity in Transnational Governance

Since 2008, a series of new regulatory initiatives have emerged to address large-scale land grabs. These initiatives are occurring simultaneously at multiple levels of social organization instead of a single, overarching institutional site. A significant portion of this activity is taking place at the transnational level. We suggest that transnational land governance is indicative of emerging shifts in the practice of governance of global affairs. We analyze such shifts by asking two related questions: what does land grabbing tell us about developments in transnational governance, particularly with regard to North-South relations, and what do these developments in transnational governance mean for regulating land grabbing?Desde 2008, ha surgido una serie de nuevas iniciativas regulatorias para tratar acaparamientos de tierra a gran escala. Estas iniciativas están sucediendo simultáneamente a niveles múltiples de la organización social en vez de un lugar institucional predominante. Una porción importante de esta actividad está tomando lugar al nivel transnacional. Sugerimos que la gobernanza de tierras trasnacionales es indicativa de los cambios que están surgiendo en la práctica de gobernanza de los asuntos globales. Analizamos tales cambios haciendo dos preguntas relacionadas: ¿qué nos dice el acaparamiento de tierras sobre los desarrollos en la gobernanza trasnacional, particularmente con las relaciones norte-sur?, y ¿qué significan estos desarrollos en gobernanza trasnacional para regular el acaparamiento de tierras