Quantum gravity without vacuum dispersion

A generic prediction of quantum gravity is the vacuum dispersion of light, and hence that a photon's speed depends on its energy. We present further numerical evidence for a scale dependent speed of light in the causal dynamical triangulation (CDT) approach to quantum gravity. We show that the observed scale dependent speed of light in CDT can be accounted for by a scale dependent transformation of geodesic distance, whose specific functional form implies a discrete equidistant area spectrum. We make two non-trivial tests of the proposed scale transformation: a comparison with the leading order quantum correction to the gravitational potential and a comparison with the generalised uncertainty principle. In both cases, we obtain the same functional form. However, contrary to the widespread prediction of vacuum dispersion in quantum gravity, numerous experiments have now definitively ruled out linear vacuum dispersion beyond Planckian energy scales, and have now even constrained quadratic dispersion. Motivated by these experimental constraints we seek to reconcile quantum gravity with the absence of vacuum dispersion. We point out that given a scale dependent geodesic distance, a scale dependent time interval becomes essential to maintaining an invariant speed of light. We show how a particular scale dependent time interval allows a photon's speed to remain independent of its energy.Comment: Version published in International Journal of Modern Physics D. 13 pages, 3 figure

Towards automated visual surveillance using gait for identity recognition and tracking across multiple non-intersecting cameras

Despite the fact that personal privacy has become a major concern, surveillance technology is now becoming ubiquitous in modern society. This is mainly due to the increasing number of crimes as well as the essential necessity to provide secure and safer environment. Recent research studies have confirmed now the possibility of recognizing people by the way they walk i.e. gait. The aim of this research study is to investigate the use of gait for people detection as well as identification across different cameras. We present a new approach for people tracking and identification between different non-intersecting un-calibrated stationary cameras based on gait analysis. A vision-based markerless extraction method is being deployed for the derivation of gait kinematics as well as anthropometric measurements in order to produce a gait signature. The novelty of our approach is motivated by the recent research in biometrics and forensic analysis using gait. The experimental results affirmed the robustness of our approach to successfully detect walking people as well as its potency to extract gait features for different camera viewpoints achieving an identity recognition rate of 73.6 % processed for 2270 video sequences. Furthermore, experimental results confirmed the potential of the proposed method for identity tracking in real surveillance systems to recognize walking individuals across different views with an average recognition rate of 92.5 % for cross-camera matching for two different non-overlapping views.<br/

Trade integration of Central and Eastern European countries: lessons from a gravity model

The aim of the paper is to analyse the factors behind the rapid trade integration of the Central and Eastern European countries with the euro area in the past ten years and to gauge the potential for further integration. We use as benchmark an enhanced gravity model estimated with a large sample of bilateral trade flows across 61 countries since 1980. We show that a careful examination of the fixed effects of the model is crucial for the proper interpretation of the results: simply extracting the predicted values of the regression (“in-sample”) – as commonly done in the literature – leads to distorted results as it fails to take the transition process properly into account. As an alternative, we propose a two-stage “out-of-sample” approach. The results suggest that trade integration between most of the largest Central and Eastern European countries and the euro area is already relatively advanced, while the Baltic countries as well as the South Eastern European countries still have significant scope for integration. JEL Classification: C23, F15, F14Central and Eastern European Countries, Free Trade Agreement, Gravity Model, panel data, Transition Economies

Recurrence networks - A novel paradigm for nonlinear time series analysis

This paper presents a new approach for analysing structural properties of time series from complex systems. Starting from the concept of recurrences in phase space, the recurrence matrix of a time series is interpreted as the adjacency matrix of an associated complex network which links different points in time if the evolution of the considered states is very similar. A critical comparison of these recurrence networks with similar existing techniques is presented, revealing strong conceptual benefits of the new approach which can be considered as a unifying framework for transforming time series into complex networks that also includes other methods as special cases. It is demonstrated that there are fundamental relationships between the topological properties of recurrence networks and the statistical properties of the phase space density of the underlying dynamical system. Hence, the network description yields new quantitative characteristics of the dynamical complexity of a time series, which substantially complement existing measures of recurrence quantification analysis

Monetary Policy Rules in Central and Eastern European Countries: Does the Exchange Rate Matter?

We estimate monetary policy rules for six central and eastern European countries (CEEC) during the period, when they prepared for membership to the EU and monetary union. By taking changes in the policy settings explicitly into account and by introducing several new methodological features we significantly improve estimation results for monetary policy rules in CEEC. We find that in the Czech Republic, Hungary and Poland the focus of the interest rate setting behaviour switched from defending the peg to targeting inflation. For Slovakia, however, there still seemed to be on ongoing focus on the exchange rate. For Slovenia and only after a policy switch for Romania we find a solid relation with inflation as well

SVZ sum rules : 30 + 1 years later

For this exceptional 25th anniversary of the QCD-Montpellier series of conferences initiated in 85 with the name "Non-perturbative methods", we take the opportunuity to celebrate the 30 + 1 years of the discovery of the SVZ (also called ITEP, QCD or QCD spectral) sum rules by M.A. Shifman, A.I. Vainshtein and V.I. Zakahrov in 79 [1]. In this talk, I have the duty to present the status of the method. I shall (can) not enumerate the vast area of successful applications of sum rules in hadron physics but I shall focus on the historical evolution of field and its new developments. More detailed related discussions and more complete references can be found in the textbooks [2,3].Comment: 8 pages, 1 figure, 4 tables, talk given at QCD 10 (15th international QCD-Montpellier conference) for the celebration of the 25th anniversary of the QCD series of Montpellier conference and of the 30+1 years discovery of the SVZ sum rule