Tracking fast neutrons

Based on elastic collisions, the linear momentum of a fast neutron can be measured from as few as two consecutive recoil ion tracks plus the vertex position of the third collision, or `two and half' ion tracks. If the time delay between the first two consecutive ion tracks is also measured, the number of ion tracks can be reduced to one and a half. The angular and magnitude resolutions are limited by ion range straggling to about ten percent. Multi-wire proportional chambers and light-field imaging are discussed for fast neutron tracking. Single-charge or single-photon detection sensitivity is required in either approach. Light-field imaging is free of charge-diffusion-induced image blur, but the limited number of photons available can be a challenge. $^1$H,$^2$H and $^3$He could be used for the initial development of fast neutron trackers based on light-field imaging.Comment: 13 pages, 14 figure

A Survey on Graph Kernels

Graph kernels have become an established and widely-used technique for solving classification tasks on graphs. This survey gives a comprehensive overview of techniques for kernel-based graph classification developed in the past 15 years. We describe and categorize graph kernels based on properties inherent to their design, such as the nature of their extracted graph features, their method of computation and their applicability to problems in practice. In an extensive experimental evaluation, we study the classification accuracy of a large suite of graph kernels on established benchmarks as well as new datasets. We compare the performance of popular kernels with several baseline methods and study the effect of applying a Gaussian RBF kernel to the metric induced by a graph kernel. In doing so, we find that simple baselines become competitive after this transformation on some datasets. Moreover, we study the extent to which existing graph kernels agree in their predictions (and prediction errors) and obtain a data-driven categorization of kernels as result. Finally, based on our experimental results, we derive a practitioner's guide to kernel-based graph classification

The Connection between Personality Traits and Perceived Stress: An In-Depth Look at How Personality Traits Can Influence Perceived Stress during an Immersion Study in a Developing Nation

The purpose of this study is to examine the relationships of the Big Five personality traits on levels of perceived student stress. A convenience sample of 28 undergraduate students (13 who were immersed in the culture of a developing nation and 15 in a normal setting) completed measures of perceived stress and the NEO-Personality Inventory. It was found that personality traits (neuroticism and extraversion) play a role in how stress is perceived, and that there is significant differences between the experimental and control groups on levels of perceived stress

'Alienated From His Own Being': Nietzsche, Bayreuth and the Problem of Identity

The abstract is included in the text