Current and Prospective Radiation Detection Systems, Screening Infrastructure and Interpretive Algorithms for the Non-Intrusive Screening of Shipping Container Cargo:A Review

The non-intrusive screening of shipping containers at national borders serves as a prominent and vital component in deterring and detecting the illicit transportation of radioactive and/or nuclear materials which could be used for malicious and highly damaging purposes. Screening systems for this purpose must be designed to efficiently detect and identify material that could be used to fabricate radiological dispersal or improvised nuclear explosive devices, while having minimal impact on the flow of cargo and also being affordable for widespread implementation. As part of current screening systems, shipping containers, offloaded from increasingly large cargo ships, are driven through radiation portal monitors comprising plastic scintillators for gamma detection and separate, typically 3He-based, neutron detectors. Such polyvinyl-toluene plastic-based scintillators enable screening systems to meet detection sensitivity standards owing to their economical manufacturing in large sizes, producing high-geometric-efficiency detectors. However, their poor energy resolution fundamentally limits the screening system to making binary “source” or “no source” decisions. To surpass the current capabilities, future generations of shipping container screening systems should be capable of rapid radionuclide identification, activity estimation and source localisation, without inhibiting container transportation. This review considers the physical properties of screening systems (including detector materials, sizes and positions) as well as the data collection and processing algorithms they employ to identify illicit radioactive or nuclear materials. The future aim is to surpass the current capabilities by developing advanced screening systems capable of characterising radioactive or nuclear materials that may be concealed within shipping containers

Using Markov Models and Statistics to Learn, Extract, Fuse, and Detect Patterns in Raw Data

Many systems are partially stochastic in nature. We have derived data driven approaches for extracting stochastic state machines (Markov models) directly from observed data. This chapter provides an overview of our approach with numerous practical applications. We have used this approach for inferring shipping patterns, exploiting computer system side-channel information, and detecting botnet activities. For contrast, we include a related data-driven statistical inferencing approach that detects and localizes radiation sources.Comment: Accepted by 2017 International Symposium on Sensor Networks, Systems and Securit

Imaging of Demyelination, Repair and Remyelination in Multiple Sclerosis

Multiple Sclerosis (MS) is characterised pathologically by both inflammatory demyelination and neurodegenerative neuroaxonal loss, occurring in varying degrees in the white matter (WM) and in the grey matter (GM). Studies of MS commonly use imaging surrogates of inflammation (e.g. MRI lesions) and neurodegeneration (e.g. atrophy) as outcome measures to assess potential neuroprotective effects. As trials of potentially remyelinating agents become more important in the spectrum of MS research, imaging outcomes sensitive to myelin, such are magnetisation transfer ratio (MTR), are required to adequately assess any such agents. With the above in mind, for this thesis, I performed 4 studies: 1. MTR and atrophy localisation in the GM using voxel-based morphometry - MRI measures of GM MTR and volume were used to assess the regional localisation of reduced MTR (in part reflecting demyelination) and atrophy (in part reflecting neuro-axonal loss) in 98 patients with MS, as well as 29 controls. Subgroups of MS patients were compared with controls, adjusting for age and gender. Overall, whilst some regionally consistent reductions in MTR and atrophy were seen in GM, this study found that these mostly do not co-localise. The differing location and extent of regional MTR and volumetric abnormalities in MS subgroups argues against a single mechanism for demyelination and neuronal loss in the GM of MS patients. 2. MRI substudy of Dronabinol (Δ⁹-THC) vs placebo – 273 patients with secondary progressive MS (SPMS) received either Dronabinol or placebo (in a ratio of 2:1), with the aim of assessing the potential neuroprotective effects of Dronobinol. T2-weighed (T2w) and T1-weighted (T1w) lesions, and percentage brain volume change (PBVC) were assessed over 3 years. Over the course of the entire study, the occurrence of new or enlarging T2w or T1w lesions, or PBVC was not affected by Dronabinol. 3. Individual lesion area MTR analysis of autologous mesenchymal stem cells (AMSC) in patients with SPMS – A proof-of-concept individual lesion area MTR analysis pathway was developed and used post-hoc on 10 patients with SPMS and optic nerve disease from the MSCIMS study, which investigated the potential reparative effects of AMSC. For T2w lesion areas, a significant difference in rate of change of MTR was noted after infusion; this was not seen with T1w lesion areas. 4. Individual lesion MTR analysis in a crossover study of AMSC in patients with active MS – the proof-of-concept work above was refined for use in STREAMS, a crossover study of AMSC. 12 patients with active MS received either AMSC or placebo for 24 weeks, and then crossover to the other arm for a further 24 weeks. MTR was measured at week 0, 12, 24, 26, and 48 in both old and newly appearing lesions. There was not noted to be any significant effect of AMSC on the MTR of either old or newly appearing lesions

Examining the Effects of One- and Three-Dimensional Spatial Filtering Analyses in Magnetoencephalography

Spatial filtering, or beamforming, is a commonly used data-driven analysis technique in the field of Magnetoencephalography (MEG). Although routinely referred to as a single technique, beamforming in fact encompasses several different methods, both with regard to defining the spatial filters used to reconstruct source-space time series and in terms of the analysis of these time series. This paper evaluates two alternative methods of spatial filter construction and application. It demonstrates how encoding different requirements into the design of these filters has an effect on the results obtained. The analyses presented demonstrate the potential value of implementations which examine the timeseries projections in multiple orientations at a single location by showing that beamforming can reconstruct predominantly radial sources in the case of a multiple-spheres forward model. The accuracy of source reconstruction appears to be more related to depth than source orientation. Furthermore, it is shown that using three 1-dimensional spatial filters can result in inaccurate source-space time series reconstruction. The paper concludes with brief recommendations regarding reporting beamforming methodologies in order to help remove ambiguity about the specifics of the techniques which have been used

Radiological diagnosis of foreign bodies in the pharynx and oesophagus

For the purpose of this paper the data of about five hundred X -ray examinations have been investigated, but only those having a particular bearing on the subject will be classified. In cases where no direct confirmation is possible,the author has adopted the following expedient.If the patient did not return to hospital following a negative X -ray examination (or examinations) this is considered as substantial proof that the X -ray report was correct. In no case was oesophagoscopy deemed necessary when the X -ray report was negative, and in no such case was an oesophagoscopy performed subsequently. A few cases originally reported as negative were re- examined,but in none was a foreign body found. The cases may be classified as follows:-a) In 98 cases,the X -ray report was negative, and no oesophagoscopy was performed. b) In 63 cases,the X -ray report was positive, but the location of the foreign body rendered interference unnecessary. c) In 15 cases,the X -ray report was positive, and the foreign body was confirmed and removed by oesophagoscopy. d) In 5 cases,the X -ray report was positive, but no foreign body was found on oesophagoscopic examination. e) In 3 cases,the X -ray report was positive, and in addition a co- existent organic lesion was reported. In these,both the foreign body and the organic lesion were confirmed by oesophagoscopy. Total number of cases investigated - 184It will be seen from these figures that a complete X -ray examination as outlined in the foregoing, performed with due care,gives extremely accurate results. In only five cases was a needless oesophagoscopy performed,thus erring on the side of safety, from the patient's point of view. In no case did the much more serious error occur of overlooking a foreign body when one was present. A closer analysis of these five failures (from the oesophagoscopic standpoint) emphasises the fact that a foreign body may pass downwards in the interim between the X -ray examination and the oesophagoscopy,and therefore the interval should be as short as conveniently possible. In four out of the five cases (Cases 30,31,33,and 34) a foreign body was indisputably present at the time of the X -ray examination,and though not found on oesophagoscopy,confirmatory evidence in the form of mucosal injuries was discovered in one of them. (Case 31). In the remaining case,the X -ray examination raised the possibility of a mucosal injury,bút could not completely exclude the presence of a foreign body. As the other evidence was in favour of a foreign body, an oesophagoscopy was performed but only a mucosal tear was found,and this was confirmed by subsequent X -ray examination. (Case 32). Taking these explanations into account,thersfore,one may take it that four out of five cases were correctly diagnosed and that the fifth failed only in being unable to exclude the presence of a foreign body in the mucosal tear that was found as reported. This standard of accuracy seems to the author to justify complete reliance on the X -ray examination

AID-RL: Active information-directed reinforcement learning for autonomous source seeking and estimation

This paper proposes an active information-directed reinforcement learning (AID-RL) framework for autonomous source seeking and estimation problem. Source seeking requires the search agent to move towards the true source, and source estimation demands the agent to maintain and update its knowledge regarding the source properties such as release rate and source position. These two objectives give rise to the newly developed framework, namely, dual control for exploration and exploitation. In this paper, the greedy RL forms an exploitation search strategy that navigates the agent to the source position, while the information-directed search commands the agent to explore most informative positions to reduce belief uncertainty. Extensive results are presented using a high-fidelity dataset for autonomous search, which validates the effectiveness of the proposed AID-RL and highlights the importance of active exploration in improving sampling efficiency and search performance