University of Bremen

About: University of Bremen is a education organization based out in Bremen, Germany. It is known for research contribution in the topics: Population & Context (language use). The organization has 14563 authors who have published 37279 publications receiving 970381 citations. The organization is also known as: Universität Bremen.

Renewable energy cooperatives as gatekeepers or facilitators? Recent developments in Germany and a multidisciplinary research agenda

Abstract: The transformation of energy systems is influencing economic policy agendas all over the world, particularly in industrialized countries. In this process, Germany has taken a pioneering role, and hence the technical innovations, legal frameworks, and business models established there are also of interest for other countries trying to achieve broader use of renewable energies. Energy cooperatives have been an important building block in the energy transition in Germany, although their practical importance is neither quantitatively nor qualitatively reflected in the academic literature. Drawing on recently collected data, this paper presents an overview of German energy cooperatives in terms of organization, financing, and membership. We then review literature from economics and the social sciences that has been used to analyze cooperatives on various levels in other fields. We discuss how these theories could be applied to create a better understanding of energy cooperatives, and we derive a preliminary research agenda for their analysis. We also assess the scope for interdisciplinary work among economists, sociologists, and other disciplines.

Black holes, gravitational waves and fundamental physics: a roadmap

Abstract: The grand challenges of contemporary fundamental physics-dark matter, dark energy, vacuum energy, inflation and early universe cosmology, singularities and the hierarchy problem-all involve gravity as a key component. And of all gravitational phenomena, black holes stand out in their elegant simplicity, while harbouring some of the most remarkable predictions of General Relativity: event horizons, singularities and ergoregions. The hitherto invisible landscape of the gravitational Universe is being unveiled before our eyes: the historical direct detection of gravitational waves by the LIGO-Virgo collaboration marks the dawn of a new era of scientific exploration. Gravitational-wave astronomy will allow us to test models of black hole formation, growth and evolution, as well as models of gravitational-wave generation and propagation. It will provide evidence for event horizons and ergoregions, test the theory of General Relativity itself, and may reveal the existence of new fundamental fields. The synthesis of these results has the potential to radically reshape our understanding of the cosmos and of the laws of Nature. The purpose of this work is to present a concise, yet comprehensive overview of the state of the art in the relevant fields of research, summarize important open problems, and lay out a roadmap for future progress. This write-up is an initiative taken within the framework of the European Action on 'Black holes, Gravitational waves and Fundamental Physics'. © 2019 IOP Publishing Ltd.

Nanoporous gold: a new material for catalytic and sensor applications

Abstract: Nanostructured materials are governed by their surface chemical properties. This is strikingly reflected by np-Au. This material can be generated by corrosion of bulk Ag–Au alloys. Based on a self-organisation process, a 3 dimensional sponge like gold structure evolves with ligaments in the range of only a few tens of nanometers. Due to its continuous porosity, the material can be penetrated by gases which then adsorb and interact with the surface. In this perspective we will review potential applications of np-Au resulting from this effect, namely heterogeneous gas phase catalysis, surface chemistry driven actuation, and adsorbate controlled stability of the nanostructure. We will summarize the current knowledge about the low temperature oxidation of CO as well as the highly selective oxidation of methanol. Furthermore, we will address the question how surface chemistry can influence the material properties itself. In particular, we will deal with (a) the actuation of np-Au by the reversible oxidation of its surface using ozone and (b) the adsorbate controlled coarsening of ligaments, using annealing experiments under ozone or inert gas atmosphere.