What is the Truth of Simulation?

To understand the epistemological meaning of simulation, it does not suffice to interpret simulation practice and theory in the framework of philosophy of science alone. Theory, experiment, measurement and observation are important activities of the scientific method. But what regards an epistemological interpretation of simulation, philosophical truth theories allow gaining additional insights. This paper discusses philosophical truth theories – e.g. the correspondence, coherence and consensus theory – and relates them to simulation practice and methodology, focussing on validation.Epistemology, Simulation, Truth Theories, Validation

The Way Forward on Counter-Terrorism: Global Perspectives

There have been thousands of public conferences and closed-door meetings on terrorism and counter-terrorism since 11 September 2001. They usually end up with recommendations and then everybody goes home after the group photo has been taken. This article will deal with the following questions: what happened to all these recommendations? Who has acted upon them and actually implemented them? Who has evaluated them? Were they any good? Specifically, it will analyze five critical issues: (i) the definition problem; (ii) the communication problem; (iii) the political problem; (iv) the religious problem; (v) the radicalization problem. Finally, it will be provided twelve rules for preventing and combating terrorism

Selected literature on radicalization and de-radicalization of terrorists: monographs, edited volumes, grey literature and prime articles published since the 1960s

International audienc

Distributed readout detectors using superconducting tunnel junctions

Superconducting tunnel junctions (STJs) are able to measure the energy of single photons in the range from near infrared to X-rays. They provide simultaneous information of the impact time and wavelength of an absorbed photon. The main difficulty of these detectors compared with conventional imaging detectors lies in their limited pixel number. Each STJ has to be connected independently and therefore the wiring becomes technologically more demanding as the number of STJs increases. One approach to solving this problem is to use a single large absorber and to distribute STJs for position sensitive signal readout. This configuration is able to detect single optical photons with an energy resolution close to that of a single STJ pixel. We have produced a Ta absorber strip with Ta/Al/AlOx/Al/Nb/Ta junctions at either end. The energy and position of single photons were measured simultaneously. The energy resolving power approaches the theoretical limit. We will present a simple Monte Carlo simulation which reproduces the measurement exactly.Comment: 3 pages, 2 figure

Understanding the Roots of Radicalisation on Twitter

In an increasingly digital world, identifying signs of online extremism sits at the top of the priority list for counter-extremist agencies. Researchers and governments are investing in the creation of advanced information technologies to identify and counter extremism through intelligent large-scale analysis of online data. However, to the best of our knowledge, these technologies are neither based on, nor do they take advantage of, the existing theories and studies of radicalisation. In this paper we propose a computational approach for detecting and predicting the radicalisation influence a user is exposed to, grounded on the notion of ’roots of radicalisation’ from social science models. This approach has been applied to analyse and compare the radicalisation level of 112 pro-ISIS vs.112 “general" Twitter users. Our results show the effectiveness of our proposed algorithms in detecting and predicting radicalisation influence, obtaining up to 0.9 F-1 measure for detection and between 0.7 and 0.8 precision for prediction. While this is an initial attempt towards the effective combination of social and computational perspectives, more work is needed to bridge these disciplines, and to build on their strengths to target the problem of online radicalisation

Silicon-Organic Hybrid (SOH) Mach-Zehnder Modulators for 100 Gbit/s On-Off Keying

Electro-optic modulators for high-speed on-off keying (OOK) are key components of short- and mediumreach interconnects in data-center networks. Besides small footprint and cost-efficient large-scale production, small drive voltages and ultra-low power consumption are of paramount importance for such devices. Here we demonstrate that the concept of silicon-organic hybrid (SOH) integration is perfectly suited for meeting these challenges. The approach combines the unique processing advantages of large-scale silicon photonics with unrivalled electro-optic (EO) coefficients obtained by molecular engineering of organic materials. In our proof-of-concept experiments, we demonstrate generation and transmission of OOK signals with line rates of up to 100 Gbit/s using a 1.1 mm-long SOH Mach-Zehnder modulator (MZM) which features a {\pi}-voltage of only 0.9 V. This experiment represents not only the first demonstration of 100 Gbit/s OOK on the silicon photonic platform, but also leads to the lowest drive voltage and energy consumption ever demonstrated at this data rate for a semiconductor-based device. We support our experimental results by a theoretical analysis and show that the nonlinear transfer characteristic of the MZM can be exploited to overcome bandwidth limitations of the modulator and of the electric driver circuitry. The devices are fabricated in a commercial silicon photonics line and can hence be combined with the full portfolio of standard silicon photonic devices. We expect that high-speed power-efficient SOH modulators may have transformative impact on short-reach optical networks, enabling compact transceivers with unprecedented energy efficiency that will be at the heart of future Ethernet interfaces at Tbit/s data rates

Code wars: steganography, signals intelligence, and terrorism

This paper describes and discusses the process of secret communication known as steganography. The argument advanced here is that terrorists are unlikely to be employing digital steganography to facilitate secret intra-group communication as has been claimed. This is because terrorist use of digital steganography is both technically and operationally implausible. The position adopted in this paper is that terrorists are likely to employ low-tech steganography such as semagrams and null ciphers instead