Second-order coherence properties of amplified spontaneous emission from a high-power tapered superluminescent diode

We study the degree of second-order coherence of the emission of a high-power multi-quantum well superluminescent diode with a lateral tapered amplifier section with and without feedback. When operated in an external cavity, the degree of second-order coherence changed from the almost thermal case of g$^{(2)}$(0)$\approx$1.9 towards the mostly coherent case of g$^{(2)}$(0)$\approx$1.2 when the injection current at the tapered section was increased. We found good agreement with semi-classical laser theory near and below threshold while above laser threshold a slightly higher g$^{(2)}$(0) was observed. As a free running device, the superluminescent diode yielded more than 400 mW of optical output power with good spatial beam quality of $M^2_{slow} < 1.6$. In this case, the DSOC dropped only slightly from 1.9 at low powers to 1.6 at the maximum output power. To our knowledge, this is the first investigation of a high-power tapered superluminescent diode concerning the degree of second-order coherence. Such a device might be useful for real-world applications probing the second order coherence function, such as ghost imaging.Comment: 8 pages, 5 figure

Is European Inter Regionalism a Relevant Approach for the World or Just for Europe? Jean Monnet/Robert Schuman Paper Series Vol. 7 No. 14 September 2007

[Introduction]. Most of the literature on inter regionalism seems to accept that, as a region, the European Union (EU) stimulates interregional cooperation in such a way that it may be responsible for adding a new category of relevant actors to world politics. This development is usually viewed by academics, mostly Europeans, positively, as a situation born from the affirmation of a European “soft power” vis-à-vis other alternatives of world order. Additionally, it is often assumed that the successful integration model of the EU is responsible for creating the conditions for emulation in other regional integration projects elsewhere, and implicitly that it could be the cornerstone of future world order. This paper explores this argument in order to provide a more accurate reading of European actions in the international landscape. Our starting point is the fact that the characteristics of the power that a nation state, or a group of nations such as the EU, exercises can be extrapolated from its internal make-up but should not be divorced from its actual behavior in the international arena. So far the behavior of the EU in that arena has been patterned along traditional lines of behavior of aspiring powers within historical settings dominated by a nation who faces problems in maintaining its hegemony. Thus, we argue that most of the literature on European “soft power” exceptionality is based on a reading of the EU internal make-up that is not paying attention to its actual behavior in the international arena. We accept that internal factors weigh on the foreign policy decisions made by a nation state or a group of nations, but also that the feeling of exceptionality – that a nation or group can develop because of its internal make-up – does not necessarily “spill over” to its international relations. So, we are going to test the proposition that, in order to protect its exceptionality, a nation state or group of nations applies different mechanisms to its international dealings, but those mechanisms are not different from the ones employed in similar international situations by nation states whose internal make-ups differ. In other words, the participation of a group of nations in the world order does not translate into a different behavior than that of previously isolated nation states, exemplified by the realist proposition that nation states and groups of nations still “value survival above all else.” And, in the case of the EU, this implies the survival of an internal make-up that has been successful for its members. As a consequence, inter regionalism can be seen as a European centered approach aimed at defending the permanence of the gains achieved by means of regional integration, but with little relevance in the medium and long term for a more democratic or more meaningful world order for developing nations. This paper contends that hegemony and emulation are just two faces of the power exercised by an actor within the international system. When a nation or group of nations has enough power to do so, it imposes its hegemony. When it does not have enough power, especially enough power to compete with an existing hegemon1 -- or it is unwilling to do so-- it would tend to emphasize other elements (its value system, for example) as an emulation horizon for other nations. Both behaviors translate into active foreign policies toward the rest of the world, and activism in foreign policy almost always is born out of the need to defend itself. In the case of the EU, its behavior towards Eastern European countries is that of a hegemon, according to the definition of hegemony in “Theorizing Regional Integration and Inter-Regional Relations (2)” (2006) – the EU establishes the goals, monitors the course of action, and supports the instruments required to carry out the undertakings agreed upon.(3) However, beyond Eastern Europe and Turkey, the EU lacks the power to impose its hegemony and is limited to resorting to an alleged “soft power” deal –i.e., inter regionalism. In the first section of this paper, we provide historical examples of the U.S., a nation state which has employed both hegemony and emulation as defense mechanisms at different stages in its history. This will demonstrate that, though much is made out of the European Union emulation, it is a mechanism to assert economic and political power that has been used before by individual nation states. And, in the second section, we discuss aspects of EU foreign policy towards developing nations that, when taken together, suggest that the adding of new relevant actors to world order by way of inter regionalism may help create a new balance of power under European tutelage, but this balance will not necessarily lead to a more democratic or lasting world order

Prospects for Turkey’s role in international politics at the beginning of the 21st century

The purpose of this working paper is to discuss Turkey’s new role in international politics at the beginning of the 21st Century and to analyse the main political and economic challenges for the country to become a regional power of medium size. The paper has three main parts. The first provides a brief overview of the main characteristics of Turkey’s international relations during the Cold War period. Then it examines Turkey’s present economic and political development in order to identify its basic handicaps and the pre-conditions necessary for becoming a regional power. The final section focuses on the future prospects of Turkey’s place in the international order. Turkey’s international relations after the Second World War were mainly determined by three interdependent factors: (1) national security; (2) economic cooperation; and (3) the country’s full integration into ‘Western civilisation’ through the so-called ‘Europeanisation process’

'Triad' or 'Tetrad'? On global changes in a dynamic world.

The US-EU race for world leadership in science and technology has become the favourite subject of recent studies. Studies issued by the European Commission reported the increase of the European share in the world's scientific production and announced world leadership of the EU in scientific output at the end of the last century. In order to be able to monitor those types of global changes, the present study is based on the 15-year period 1991-2005. A set of bibliometric and technometric indicators is used to analyse activity and impact patterns in science and technology output. This set comprises publication output indicators such as (1) the share in the world total, (2) subject-based publication profiles, (3) citation-based indicators like journal- and subject-normalised mean citation rates, (4) international co-publications and their impact as well as (5) patent indicators and publication-patent citation links (both directions). The evolution of national bibliometric profiles, 'scientific weight' and science-technology linkage patterns are discussed as well. The authors show, using the mirror of science and technology indicators, that the triad model does no longer hold in the 21st century. China is challenging the leading sciento-economic powers and the time is approaching when this country will represent the world's second largest potential in science and technology. China and other emerging scientific nations like South Korea, Taiwan, Brazil and Turkey are already changing the balance of power as measured by scientific production, as they are at least in part responsible for the relative decline of the former triad.Research; World; Science; Science-and-technology; Technology; Studies; Order; Indicators; Impact; Patterns; International; Patent; Linkage; Model; Power; Time; Country;

Finding Statistically Significant Interactions between Continuous Features

The search for higher-order feature interactions that are statistically significantly associated with a class variable is of high relevance in fields such as Genetics or Healthcare, but the combinatorial explosion of the candidate space makes this problem extremely challenging in terms of computational efficiency and proper correction for multiple testing. While recent progress has been made regarding this challenge for binary features, we here present the first solution for continuous features. We propose an algorithm which overcomes the combinatorial explosion of the search space of higher-order interactions by deriving a lower bound on the p-value for each interaction, which enables us to massively prune interactions that can never reach significance and to thereby gain more statistical power. In our experiments, our approach efficiently detects all significant interactions in a variety of synthetic and real-world datasets.Comment: 13 pages, 5 figures, 2 tables, accepted to the 28th International Joint Conference on Artificial Intelligence (IJCAI 2019

Deeply virtual electroproduction of photons and mesons on the nucleon

We give predictions for the leading order amplitudes for deeply virtual Compton scattering and hard meson electroproduction reactions at large Q^2 in the valence region in terms of skewed quark distributions. We give first estimates for the power corrections to these leading order amplitudes. In particular, we outline examples of experimental opportunities to access the skewed parton distributions at the current high-energy lepton facilities : JLab, HERMES and COMPASS.Comment: 4 pages, 4 figures. Invited talk at XVth Particles and Nuclei International Conference (PANIC 99), Uppsala, Sweden, 10-16 June 1999. To be published by World Scientific (Singapore