Geodetic data shed light on ongoing caldera subsidence at Askja, Iceland

Subsidence within the main caldera of Askja volcano in the North of Iceland has been in progress since 1983. Here, we present new ground- and satellite-based deformation data, which we interpret together with new and existing micro-gravity data, to help understand which processes may be responsible for the unrest. From 2003 to 2007, we observe a net micro-gravity decrease combined with subsidence and from 2007 to 2009 we observe a net micro-gravity increase while the subsidence continues. We infer subsidence is caused by a combination of a cooling and contracting magma chamber at a divergent plate boundary. Mass movements at active volcanoes can be caused by several processes, including water table/lake level movements, hydrothermal activity and magma movements. We suggest that, here, magma movement and/or a steam cap in the geothermal system of Askja at depth are responsible for the observed micro-gravity variations. In this respect, we rule out the possibility of a shallow intrusion as an explanation for the observed micro-gravity increase but suggest magma may have flowed into the residing shallow magma chamber at Askja despite continued subsidence. In particular, variable compressibility of magma residing in the magma chamber as well as compressibility of the surrounding rock may be the reason why this additional magma did not create any detectable surface deformation.     

Determination of carrying capacity for Sheep‐breeding in Southern Greenland by means of Satellite mapping

Arctic and sub‐arctic areas can be regarded as very less favored in consideration to agricultural production. In the southern Greenland sheep‐breeding is crucial for the self‐reliance economy. The article deals with a mapping project that was carried out in order to assess the carrying capacity. The natural conditions are briefly described as background for the mapping which by means of NDVI and Principal Component Analysis of Landsat MSS data has proven very powerful. The aspects of growing season, climate and landscape variation are discussed.

The investigation was carried out at Institute for Geography, Socio‐Economic Analysis and Computer Science, Roskilde University Centre, Denmark.     

Governance arrangements targeting diversity in Europe: how New Public Management impacts working with social cohesion

This article analyses how policies to foster social cohesion within diverse and unequal urban contexts are affected by New Public Management and austerity policies. Based on the analysis of a handful of governance arrangements in three cities that differ in their institutional structure and diversity policy approaches (Copenhagen, Leipzig and Milan), it is shown that negative effects are quite widespread yet cushioned by a strong welfare state structure, solid local government and high priority given to the recognition of diversity. Nevertheless, the shift towards the application of market logic to social work reduces innovative potential, increases efforts spent on procedures and weakens public coordination.     

Dynamics of an ultra-relativistic, collisionless astrophysical plasma

We consider the evolution of a collisionless proton-electron plasma with an initial Lorentz factor ?? ?? 223 in the vicinities of astrophysical objects such as black holes, gamma-ray bursts, etc. A three-dimensional, numerical model describing the interaction of the plasma with the electromagnetic field in the Vlasov-Maxwell equations is used to simulate the flow of a relativistic neutral plasma. The modeling results can be used to estimate the conversion of the proton kinetic energy to the energy of electrons and the electromagnetic field.     

Influence of Thermal Air Pollution on the Urban Climate (Estimates Using the COSMO-CLM Model)

Izvestiya, Atmospheric and Oceanic Physics - It is well known that large cities and urban agglomerations not only make a decisive contribution to the growth of greenhouse gases in the atmosphere,...     

On the generation mechanism of hard cosmic gamma-ray emission from AGN jets

We consider the mechanism for the generation of high-energy cosmic gamma rays through the inelastic interaction of relativistic protons (due to their velocity dispersion) accelerated by a self-consistent electromagnetic field in an electron-positron jet plasma. The velocity dispersion is explained by the growth of a plasma instability in a relativistic jet.     

Plasma instability in relativistic jets

Based on the Maxwel-Vlasov equations, we consider the possible generation mechanisms of hard emission through the growth of plasma instabilities in a relativistic jet composed of electrons and protons. The accelerated material of the jet moves by inertia. When a small difference arises between the electron and proton velocities (which may result from the interaction of jet material with background plasma or from the acceleration mechanism) plasma instabilities can grow. The particle distribution functions, which were initially delta functions both in angle and in energy, transform into complex angular and energy dependences. In this case, the probability of collisions between high-energy particles in the jet increases, resulting in hard gamma-ray emission.     

Impacts of – and farmers’ adaptation to – land allocation policies in the north central uplands of Vietnam

A series of policies on land tenure have been implemented in Vietnam following the doi moi restructuring. This study assesses the impacts of these policies, the extent to which they have had intended effects and coping strategies adopted by farmers. Data were collected in five upland villages in Nghe An Province, North Central Vietnam. The intended effects of the land allocation policies were poverty alleviation, intensification of agriculture, agricultural modernization and forest protection. The policies implemented to achieve these goals include changes in land allocation, purportedly to increase land tenure security. However, the policies have been implemented in a very uneven manner and the effects differ widely due to differences in the local contexts in which they have been implemented. In general, farmers perceive the impacts of policies as adverse and have attempted to cope with their impact in a variety of ways. The paper argues that land allocation policies have: (1) decreased the amount of land available, (2) not improved land tenure security and (3) had a limited impact on farming practices. The differences between the five villages are great, demonstrating the very different results produced by national policies depending on the specific implementation modality and the local context.