S-matrix network models for coherent waves in random media: construction and renormalization

Networks of random quantum scatterers (S-matrices) form paradigmatic models for the propagation of coherent waves in random S-matrix network models cover universal localization-delocalization properties and have some advantages over more traditional Hamiltonian models. In particular, a straightforward implementation of real space renormalization techniques is possible. Starting from a finite elementary cell of the S-matrix network, hierarchical network models can be constructed by recursion. The localization-delocalization properties are contained in the flow of the forward scattering strength ('conductance') under increasing system size. With the aid of 'small scale' numerics qualitative aspects of the localization-delocalization properties of S-matrix network models can be worked out.Comment: 10 pages, LaTeX, 8 eps figures included, proceedings PILS98, to be published in Annalen der Physi

Nationale Strategien für nachhaltige Biomassenutzung in Afrika

Nachhaltige Biomassenutzung ist auch in Afrika auf dem Vormarsch. Nationale Strategien sowie rechtliche und ordnungspolitische Rahmenbedingungen spielen dabei eine wichtige Rolle. Welche Bedeutung hat die Anpassung solcher Strategien auf die jeweiligen nationalen, regionalen und lokalen Begebenheiten

Carbon Labelling in Europe Final Report of the Carbon Labelling Project

The Carbon Labelling project implemented several labelling measures in Europe focused on transportation products and services with low CO2 emissions. The project promoted biodiesel, low-viscosity lubricants and ‘low carbon’ freight services. This first European carbon labelling initiative supported the discussion about measures for the greenhouse gas reduction (GHG) targets of the European Union and the role of biofuels to mitigate GHG emissions. Carbon life cycle numbers were calculated with GHG models from leading European research institutes. The identified carbon reduction numbers were used for pilot labelling initiatives via the label “CO2Star” developed by a professional advertising agency. The label and consumer information websites provided information to consumers about environmental and economic benefits of the labelled biofuels, lubricants and freight services. For instance, the German fuel distributor Q1 implemented a carbon labelling pilot programme for biodiesel (B 100) and lubricants at its fuel stations, while Dutch horticulture freight companies implemented the carbon label to promote "low carbon" freight services

Best Practice Report : Smart Specialisation Strategies and SET plan implementation actions

This report describes how countries and regions are successfully putting into practice the principles of Smart Specialisation, drawing lessons for TRACER partner regions. Smart Specialisation suggests that the most effective way to deliver innovation, and ultimately regional or national economic development, is to concentrate public and private interventions and resources on a limited number of priorities, based on national/regional strengths. The three case study regions explored in detail in this report – South Limburg (Netherlands), Asturias (Spain) and North-Rhine Westphalia (Germany) - share a history in coal mining, while being diverse in terms of their geographies, transition stages and sectors of specialisation. However, within these different contexts, Smart Specialisation strategies have played a key role in the innovation focus of such regions and in their transition out of coal, partly using the competitive advantages they may have in the production and transportation of energy sources. Besides their Smart Specialisation strategies, the mining history, wider transition policies, challenges and change-enabling conditions show how (former) coal regions have been handling economic diversification and structural adaptation. Together, the longitudinal historical processes and current innovation strategies that shape these regions may be an important resource for S3 and wider transition policies in coal-intensive regions elsewhere. Finally, the Strategic Energy Technology (SET) Plan has been the research and innovation pillar of the EU's energy and climate policy since 2007, coordinating low-carbon research and innovation activities in EU Member States, Iceland, Norway, Switzerland and Turkey. The SET Plan helps structure European and national research programmes and triggers substantial investments on common priorities in low-carbon technologies. The implementation of SET Plan Implementation Plans is currently not directly linked with existing R&I strategies for the transition in coal intensive regions. However, the coming years will produce opportunities and potential synergies for SET Plan Implementation Plans with activities in most TRACER target regions facilitating their transition towards a sustainable energy system. Further, TRACER target regions can potentially learn from the best practice projects linked to achieving SET Plan targets

Localization in non-chiral network models for two-dimensional disordered wave mechanical systems

Scattering theoretical network models for general coherent wave mechanical systems with quenched disorder are investigated. We focus on universality classes for two dimensional systems with no preferred orientation: Systems of spinless waves undergoing scattering events with broken or unbroken time reversal symmetry and systems of spin 1/2 waves with time reversal symmetric scattering. The phase diagram in the parameter space of scattering strengths is determined. The model breaking time reversal symmetry contains the critical point of quantum Hall systems but, like the model with unbroken time reversal symmetry, only one attractive fixed point, namely that of strong localization. Multifractal exponents and quasi-one-dimensional localization lengths are calculated numerically and found to be related by conformal invariance. Furthermore, they agree quantitatively with theoretical predictions. For non-vanishing spin scattering strength the spin 1/2 systems show localization-delocalization transitions.Comment: 4 pages, REVTeX, 4 figures (postscript

Triplets of supermassive black holes: Astrophysics, Gravitational Waves and Detection

Supermassive black holes (SMBHs) found in the centers of many galaxies have been recognized to play a fundamental active role in the cosmological structure formation process. In hierarchical formation scenarios, SMBHs are expected to form binaries following the merger of their host galaxies. If these binaries do not coalesce before the merger with a third galaxy, the formation of a black hole triple system is possible. Numerical simulations of the dynamics of triples within galaxy cores exhibit phases of very high eccentricity (as high as $e \sim 0.99$). During these phases, intense bursts of gravitational radiation can be emitted at orbital periapsis. This produces a gravitational wave signal at frequencies substantially higher than the orbital frequency. The likelihood of detection of these bursts with pulsar timing and the Laser Interferometer Space Antenna ({\it LISA}) is estimated using several population models of SMBHs with masses $\gtrsim 10^7 {\rm M_\odot}$. Assuming a fraction of binaries $\ge 0.1$ in triple system, we find that few to few dozens of these bursts will produce residuals $>1$ ns, within the sensitivity range of forthcoming pulsar timing arrays (PTAs). However, most of such bursts will be washed out in the underlying confusion noise produced by all the other 'standard' SMBH binaries emitting in the same frequency window. A detailed data analysis study would be required to assess resolvability of such sources. Implementing a basic resolvability criterion, we find that the chance of catching a resolvable burst at a one nanosecond precision level is 2-50%, depending on the adopted SMBH evolution model. On the other hand, the probability of detecting bursts produced by massive binaries (masses \gtrsim 10^7\msun) with {\it LISA} is negligible.Comment: Accepted for publication by MNRAS, minor change

Smart strategies for the transition in coal intensive regions

The TRACER project supports a number of coal-intensive regions around Europe to design (or re-design) their Research and Innovation (R&I) strategies in order to facilitate their transition towards a sustainable energy system. The TRACER consortium consists of different target regions: South East Bulgaria, North West Bohemia - Czech Republic, Lusatian Lignite District - Germany, Western Macedonia - Greece, Upper Silesian Coalfield - Poland, West Region, Jiu Valley - Romania, Wales – UK, Kolubara - Serbia, Donetsk - Ukraine. Core activities of TRACER include the implementation of an EDP (Entrepreneurial Discovery Process) to mobilise a wide range of stakeholders in each target region to develop an appropriate governance structure and to bring regional stakeholders together to discuss and agree on a shared vision and priorities for coal transition. R&I strategies, industrial roadmaps and decision support tools will be developed jointly with key stakeholders of the TRACER target regions. Further TRACER activities include the identification and analysis of best practice examples of successful and ambitious transition processes in coal intensive regions, a detailed assessment of social, environmental and technological challenges, the elaboration of guidelines on how to mobilise investment as well as dedicated activities to stimulate R&I cooperation among coal intensive regions in Europe and beyond