Environmental engineering for quantum energy transport

Transport phenomena are ubiquitous throughout the science, engineering and technology disciplines as it concerns energy, mass, charge and information exchange between systems. In particular, energy transport in the nanoscale regime has attracted significant attention within the physical science community due to its potential to explain complex phenomena like the electronic energy transfer in molecular crystals or the Fenna-Matthews-Olson / light harvesting complexes in photosynthetic bacteria with long time coherences. Energy transport in these systems is highly affected by environmental noise but surprisingly not always in a detrimental way. It was recently found that situations exist where noise actually enhances the transport phenomena. Such noise can take many forms, but can be characterised in three basic behaviours: quantum, coloured or nonlocal. All have been shown potential to offer an energy transport enhancement. The focus of this work is on quantum transport caused by stochastic environment with spatio-temporal correlation. We consider a multi-site nearest neighbour interaction model with pure dephasing environmental noise with coloured and nonlocal character and show how an accelerated rate for the energy transfer results especially under anti-correlation. Negative spatial correlations provide another control parameter to help one establish the most efficient transfer of energy and may provide new insights into the working of exciton transport in photosynthetic complexes. Further the usage of spatio-temporal correlated noise may be a beneficial resource for efficient transport in large scale quantum networks.Comment: 11 pages 5 figure

Comparing measures of competitiveness

In their Europe Agreements with the EU, the Central and Eastern European countries stated their intention of joining the Union. To ease the process of accession these countries must adjust their economies already prior to becoming an EU-member. Agriculture requires special attention, because it still represents a large share of the total economy in these countries. A better understanding of the competitiveness of agricultural products at domestic and EU markets is essential for providing the necessary economic framework to make the process of joining the EU as smooth as possible.Competitiveness can be analyzed at various levels of the economy: at the enterprise level, the sector level, or the level of the entire economy. Several measures exist for each of these levels. This paper focuses on those used for sector analysis. Since the measures commonly employed for this purpose do not deliver the same results, a better understanding of the underlying causes is necessary. This paper discusses the differences between the various indicators. It identifies the factors leading to disagreement in the results obtained. -- G E R M A N V E R S I O N: In den Assoziierungsabkommen mit der EU haben die mittel- und osteuropäischen Länder ihr Interesse an einer EU-Mitgliedschaft bekundet. Um den Integrationsprozeß zu erleichtern, müssen diese Länder ihre Wirtschaft anpassen. Die Landwirtschaft verdient dabei besondere Aufmerksamkeit, da sie einen nicht geringen Anteil an der gesamten wirtschaftlichen Leistung erbringt. Kenntnis über die Wettbewerbsfähigkeit landwirtschaftlicher Produkte dieser Länder ermöglicht es, die ökonomischen Voraussetzungen für einen möglichst reibungslosen Übergang in die EU zu erreichen. Wettbewerbsfähigkeit läßt sich auf verschiedenen Stufen der Wirtschaft messen; auf betrieblicher Ebene, für einen Sektor oder für die gesamte Volkswirtschaft. Auf jeder dieser Stufen gibt es verschiedene Indikatoren. In diesem Diskussionspapier werden solche Indikatoren beschrieben, die zur Messung der Wettbewerbsfähigkeit auf sektoraler Ebene herangezogen werden können. Da sich die Meßzahlen unterscheiden und auch nicht zwingend die gleichen Ergebnisse liefern, ist die Kenntnis der Gründe für diese Abweichungen in den Ergebnissen sehr wichtig. Dieses Papier untersucht und beschreibt die Faktoren, die zu derartigen Unterschieden führen.

Fit for planning? An evaluation of the application of development viability appraisal models in the UK planning system

The aim of this paper is to critically examine the application of development appraisal to viability assessment in the planning system. This evaluation is of development appraisal models in general and also their use in particular applications associated with estimating planning obligation capacity. The paper is organised into four themes: · The context and conceptual basis for development viability appraisal · A review of development viability appraisal methods · A discussion of selected key inputs into a development viability appraisal · A discussion of the applications of development viability appraisals in the planning system It is assumed that readers are familiar with the basic models and information needs of development viability appraisal rather than at the cutting edge of practice and/or academ

Social capital and regional economic growth

We study a cross-section of 54 European regions in the period 1950-1998. The central question is whether social capital, in the form of generalized trust and associational activity, is related to regional differences in economic growth. Based on extensive robustness tests, we present evidence that social capital measured as associational activity is positively related to growth differentials in European regions. Hence, our results suggest that Putnam’s (1993) thesis on social capital in Italian regions can be generalized. Our analysis also suggests that it is not only the mere existence of network relationships that stimulates regional economic growth, but also the level of actual involvement in these relationships.

Key Generation in Wireless Sensor Networks Based on Frequency-selective Channels - Design, Implementation, and Analysis

Key management in wireless sensor networks faces several new challenges. The scale, resource limitations, and new threats such as node capture necessitate the use of an on-line key generation by the nodes themselves. However, the cost of such schemes is high since their secrecy is based on computational complexity. Recently, several research contributions justified that the wireless channel itself can be used to generate information-theoretic secure keys. By exchanging sampling messages during movement, a bit string can be derived that is only known to the involved entities. Yet, movement is not the only possibility to generate randomness. The channel response is also strongly dependent on the frequency of the transmitted signal. In our work, we introduce a protocol for key generation based on the frequency-selectivity of channel fading. The practical advantage of this approach is that we do not require node movement. Thus, the frequent case of a sensor network with static motes is supported. Furthermore, the error correction property of the protocol mitigates the effects of measurement errors and other temporal effects, giving rise to an agreement rate of over 97%. We show the applicability of our protocol by implementing it on MICAz motes, and evaluate its robustness and secrecy through experiments and analysis.Comment: Submitted to IEEE Transactions on Dependable and Secure Computin

Social Capital and Regional Economic Growth

We study a cross-section of 54 European regions in the period 1950-1998.The central question is whether social capital, in the form of generalized trust and associational activity, is related to regional differences in economic growth. Based on extensive robustness tests, we present evidence that Fukuyama's (1995) argument on trust does not hold and that Putnam's (1993) thesis on group membership in Italian regions can be generalized.Our analysis suggests that it is not only the mere existence of network relationships that stimulates regional economic growth, but also the level of actual involvement in these relationships.networks;regional development;social capital;trust

Byzantine Attack and Defense in Cognitive Radio Networks: A Survey

The Byzantine attack in cooperative spectrum sensing (CSS), also known as the spectrum sensing data falsification (SSDF) attack in the literature, is one of the key adversaries to the success of cognitive radio networks (CRNs). In the past couple of years, the research on the Byzantine attack and defense strategies has gained worldwide increasing attention. In this paper, we provide a comprehensive survey and tutorial on the recent advances in the Byzantine attack and defense for CSS in CRNs. Specifically, we first briefly present the preliminaries of CSS for general readers, including signal detection techniques, hypothesis testing, and data fusion. Second, we analyze the spear and shield relation between Byzantine attack and defense from three aspects: the vulnerability of CSS to attack, the obstacles in CSS to defense, and the games between attack and defense. Then, we propose a taxonomy of the existing Byzantine attack behaviors and elaborate on the corresponding attack parameters, which determine where, who, how, and when to launch attacks. Next, from the perspectives of homogeneous or heterogeneous scenarios, we classify the existing defense algorithms, and provide an in-depth tutorial on the state-of-the-art Byzantine defense schemes, commonly known as robust or secure CSS in the literature. Furthermore, we highlight the unsolved research challenges and depict the future research directions.Comment: Accepted by IEEE Communications Surveys and Tutoiral

The backbone of the climate network

We propose a method to reconstruct and analyze a complex network from data generated by a spatio-temporal dynamical system, relying on the nonlinear mutual information of time series analysis and betweenness centrality of complex network theory. We show, that this approach reveals a rich internal structure in complex climate networks constructed from reanalysis and model surface air temperature data. Our novel method uncovers peculiar wave-like structures of high energy flow, that we relate to global surface ocean currents. This points to a major role of the oceanic surface circulation in coupling and stabilizing the global temperature field in the long term mean (140 years for the model run and 60 years for reanalysis data). We find that these results cannot be obtained using classical linear methods of multivariate data analysis, and have ensured their robustness by intensive significance testing.Comment: 6 pages, 5 figure