How can the literature inform counter-terrorism practice? Recent advances and remaining challenges

In 2014 an intense debate over the state of terrorism literature was published. Sageman [2014. The stagnation in terrorism research. Terrorism and Political Violence, 26(4), 565–580. doi:10.1080/09546553.2014.895649] claimed that the field had stagnated, mainly due to lack of data sharing between government departments that have access to valuable information that could inform our understanding, and researchers who have the skills and expertise to make sense of this. However, others were more positive regarding the literature, highlighting areas where progress has been made [e.g. McCauley, & Moskalenko (2014). Some things We think We've learned since 9/11: A commentary on Marc Sageman's ‘The stagnation in terrorism research'. Terrorism and Political Violence, 26(4), 601–606. doi:10.1080/09546553.2014.895653; Stern (2014). Response to Marc Sageman's ‘The stagnation in terrorism research'. Terrorism and Political Violence, 26(4), 607–613. doi:10.1080/09546553.2014.895654; Taylor (2014). If I were you, I wouldn't start from here: Response to Marc Sageman's The stagnation in terrorism research’. Terrorism and Political Violence, 26(4), 581–586. doi:10.1080/09546553.2014.895650]. Here we re-visit the literature and identify advances that have been made since 2014. We explore ongoing challenges for terrorism researchers and practitioners, and options for ways forward to ensure evidence-based responses to terrorist individuals and groups

Super-harmonic injection locking of nano-contact spin-torque vortex oscillators

Super-harmonic injection locking of single nano-contact (NC) spin-torque vortex oscillators (STVOs) subject to a small microwave current has been explored. Frequency locking was observed up to the fourth harmonic of the STVO fundamental frequency $f_{0}$ in microwave magneto-electronic measurements. The large frequency tunability of the STVO with respect to $f_{0}$ allowed the device to be locked to multiple sub-harmonics of the microwave frequency $f_{RF}$, or to the same sub-harmonic over a wide range of $f_{RF}$ by tuning the DC current. In general, analysis of the locking range, linewidth, and amplitude showed that the locking efficiency decreased as the harmonic number increased, as expected for harmonic synchronization of a non-linear oscillator. Time-resolved scanning Kerr microscopy (TRSKM) revealed significant differences in the spatial character of the magnetization dynamics of states locked to the fundamental and harmonic frequencies, suggesting significant differences in the core trajectories within the same device. Super-harmonic injection locking of a NC-STVO may open up possibilities for devices such as nanoscale frequency dividers, while differences in the core trajectory may allow mutual synchronisation to be achieved in multi-oscillator networks by tuning the spatial character of the dynamics within shared magnetic layers.Comment: 21 pages, 8 figure

Direct observation of magnetization dynamics generated by nano-contact spin-torque vortex oscillators

Time-resolved scanning Kerr microscopy has been used to directly image the magnetization dynamics of nano-contact (NC) spin-torque vortex oscillators (STVOs) when phase-locked to an injected microwave (RF) current. The Kerr images reveal free layer magnetization dynamics that extend outside the NC footprint, where they cannot be detected electrically, but which are crucial to phase-lock STVOs that share common magnetic layers. For a single NC, dynamics were observed not only when the STVO frequency was fully locked to that of the RF current, but also for a partially locked state characterized by periodic changes in the core trajectory at the RF frequency. For a pair of NCs, images reveal the spatial character of dynamics that electrical measurements show to have enhanced amplitude and reduced linewidth. Insight gained from these images may improve understanding of the conditions required for mutual phase-locking of multiple STVOs, and hence enhanced microwave power emission.Comment: 10 pages, 3 figure

Time-resolved investigation of magnetization dynamics of arrays of non-ellipsoidal nanomagnets with a non-uniform ground state

We have performed time-resolved scanning Kerr microscopy (TRSKM) measurements upon arrays of square ferromagnetic nano-elements of different size and for a range of bias fields. The experimental results were compared to micromagnetic simulations of model arrays in order to understand the non-uniform precessional dynamics within the elements. In the experimental spectra two branches of excited modes were observed to co-exist above a particular bias field. Below the so-called crossover field, the higher frequency branch was observed to vanish. Micromagnetic simulations and Fourier imaging revealed that modes from the higher frequency branch had large amplitude at the center of the element where the effective field was parallel to the bias field and the static magnetization. Modes from the lower frequency branch had large amplitude near the edges of the element perpendicular to the bias field. The simulations revealed significant canting of the static magnetization and the effective field away from the direction of the bias field in the edge regions. For the smallest element sizes and/or at low bias field values the effective field was found to become anti-parallel to the static magnetization. The simulations revealed that the majority of the modes were de-localized with finite amplitude throughout the element, while the spatial character of a mode was found to be correlated with the spatial variation of the total effective field and the static magnetization state. The simulations also revealed that the frequencies of the edge modes are strongly affected by the spatial distribution of the static magnetization state both within an element and within its nearest neighbors

Effects of pretesting implicit self-determined motivation on behavioural engagement: evidence for the mere measurement effect at the implicit level

Research into individuals' intended behavior and performance has traditionally adopted explicitly measured, self-report constructs, and outcomes. More recently, research has shown that completing explicit self-report measures of constructs may effect subsequent behavior, termed the "mere measurement" effect. The aim of the present experiment was to investigate whether implicit measures of motivation showed a similar mere measurement effect on subsequent behavior. It may be the case that measuring the implicit systems affects subsequent implicit interventions (e.g., priming), observable on subsequent behavior. Priming manipulations were also given to participants in order to investigate the interaction between measurement and priming of motivation. Initially, a 2 [implicit association test (IAT: present vs. absent) ×2 (Prime: autonomous vs. absent) and a 2 (IAT: present vs. absent) × 2 (Prime: controlled vs. absent)] between participants designs were conducted, these were them combined into a 2 (IAT: present vs. absent) ×3 (Prime: autonomous vs. controlled vs. absent) between participants design, with attempts at a novel task taken as the outcome measure. Implicit measure completion significantly decreased behavioral engagement. Priming autonomous motivation significantly facilitated, and controlled motivation significantly inhibited performance. Finally, there was a significant implicit measurement × priming interaction, such that priming autonomous motivation only improved performance in the absence of the implicit measure. Overall, this research provides an insight into the effects of implicit measurement and priming of motivation and the combined effect of completing both tasks on behavior

Lay causes of binge drinking in the United Kingdom and Australia: a causal network diagram approach

Binge drinking is associated with deleterious health, social and economic outcomes. This study explored the lay understanding of the causes of binge drinking in members of the general public in the United Kingdom and Australia. Participants in the United Kingdom (N = 133) and Australia (N = 102) completed a network diagram exercise requiring them to draw causal paths and provide path strength ratings between 12 candidate factors (24-h opening, age, alcohol advertizing, alcohol availability, boredom, drinking culture, income, low cost, parental influence, peer pressure, stress and supermarket discounts) and binge drinking. Results indicated good consistency in paths across samples, although differences in frequency and strength ratings for some paths were found. Drinking culture, peer pressure and low alcohol cost were perceived as direct causes of binge drinking in both samples. Low alcohol cost and drinking culture were most frequently viewed as direct causes of binge drinking in UK and Australian participants, respectively. Supermarket discounts and low cost of alcohol were most frequently viewed as indirect causes of binge drinking by UK and Australian samples. Findings reflect general awareness and prominence of factors affecting binge drinking in both national groups. Findings may inform the development of campaigns to promote public support policies to curb binge drinking

Time-resolved imaging of magnetization dynamics in double nanocontact spin torque vortex oscillator devices

This is the published version. Available from the American Physical Society via the DOI in this recordDouble nanocontact (NC) spin transfer vortex oscillator devices, in which NCs of 100-nm diameter have center-to-center separation ranging from 200 to 1100 nm, have been studied by means of electrical measurements and time-resolved scanning Kerr microscopy (TRSKM). The NCs were positioned close to the edge of the top electrical contact so that the magnetization dynamics of the adjacent region could be probed optically. The electrical measurements showed different ranges of frequency operation for devices with different NC separations. For 900-nm NC separation, TRSKM showed magnetic contrast consistent with the formation of a magnetic vortex at each NC, while for 200-nm NC separation a lack of magnetic contrast near the NC region suggests that the magnetization dynamics occur closer to the NC and underneath the top contact. TRSKM also reveals the presence of additional localized dynamical features far from the NCs, which are not seen by electrical measurements; has not been reported previously for double NCs with different separations; and provides insight into how the dynamic state of the phase-locked oscillators is established and stabilized.Engineering and Physical Sciences Research Council (EPSRC)Ministry of Education, Chile and Commission for Scientific and Technological Research (CONICYT