Imaging single barium atoms in solid xenon for barium tagging in the nEXO neutrinoless double beta decay experiment

2016 Spring.Includes bibliographical references.The nEXO experiment will search for neutrinoless double beta decay of the isotope 136Xe in a ton-scale liquid xenon time projection chamber, in order to probe the Majorana nature of neutrinos. Detecting the daughter 136Ba of double beta decay events, called barium tagging, is a technique under investigation which would provide a veto for a background-free measurement. This would involve detecting a single barium ion from within a macroscopic volume of liquid xenon. One proposed barium tagging method is to trap the barium ion in solid xenon at the end of a cold probe, and then detect it by its fluorescence in the solid xenon. In this thesis, new studies on the spectroscopy of deposits of Ba and Ba+ in solid xenon are presented. Imaging of barium atoms in solid xenon is demonstrated with sensitivity down to the single atom level. Achievement of this level of sensitivity is a major step toward barium tagging by this method

The quality of experience of next generation audio :exploring system, context and human influence factors

PhD ThesisThe next generation of audio reproduction technology has the potential to deliver immersive and personalised experiences to the user; multichannel with-height loudspeaker arrays and binaural techniques offer 3D audio experiences, whereas objectbased techniques offer possibilities of adapting content to suit the system, context and user. A fundamental process in the advancement of such technology is perceptual evaluation. It is crucial to understand how listeners perceive new technology in order to drive future developments. This thesis explores the experience provided by next generation audio technology by taking a quality of experience (QoE) approach to evaluation. System, context and human factors all influence QoE and in this thesis three case studies are presented to explore the role of these categories of influence factors (IFs) in the context of next generation audio evaluation. Furthermore, these case studies explore suitable methods and approaches for the evaluation of the QoE of next generation audio with respect to its various IFs. Specific contributions delivered from these individual studies include a subjective comparison between soundbar and discrete surround sound technology, the application of the Open Profiling of Quality method to the field of audio evaluation, an understanding of both how and why environmental noise influences preferred audio object balance, an understanding of how the influence of technical audio quality on overall listening experience is related to a range of psychographic variables and an assessment of the impact of binaural processing on overall listening experience. When considering these studies as a whole, the research presented here contributes the thesis that to effectively evaluate the perceived quality of next generation audio, a QoE mindset should be taken that considers system, context and human IFs.Engineering and Physical Sciences Research Council (EPSRC) and the British Broadcasting Corporation Research & Development department (BBC R&D

Perspectives on the application of technology to enhance learning in an undergraduate nursing degree programme

This paper discusses concepts and practice relating to the use of computer-based technologies for enhancing learning. It draws on examples from a UK nursing degree programme

Subjective Logic and Arguing with Evidence

Peer reviewedPreprin

Bridging the Gap between Object-oriented and Logic Programming

A description is given of an interface that was developed between Loops and Xerox Quintus Prolog. Loops is an extension to the Xerox AI environment to support object-oriented programming; Xerox Quintus Prolog is a version of Prolog that runs on Xerox Lisp machines. Such a bridge enables all the support tools of both environments to be accessed, and degradation of performance that occurs when one language is implemented top of another is avoided. The interface has three layers. At the lowest level, a set of Prolog predicates gives the Prolog programmer access to Loops objects. This lowest level is the bridge from Prolog to Loops. At the next level, programming tools in the Loops environment let object methods be defined in Prolog. At the highest level, the Prolog programmer can treat Prolog clauses as Loops objects that can be manipulated outside the Prolog database. Each layer can be used independently

Inclusion of those with Mental Health Issues

What is it like to live every day with mental health challenges? How can we be inclusive of those dealing with issues related to mental health? What can you do to support your colleagues who may have mental health challenges themselves or in their family

Developing an internal timber veneer lining system for XLam cross-laminated timber

The project undertakes a product development strategy for the delivery of an ‘internal timber veneer lining system’. The internal timber veneer lining system shall be used for lining the interior walls of buildings constructed using XLam Cross-Laminated Timber panels and elements. The stages of product development are: 1. Undertake market research and market validation processes to identify a unique value proposition for the internal timber veneer lining system. 2. Conduct an experimental research process exploring material use, design features and functionality, to be included in the prototype timber veneer lining system design. 3. Write a Product Requirements Document (PRD) for the interior timber veneer lining system, accompanied by quantitative and qualitative analyses for the delivery of the prototype system design. 4. Document each stage of the project to ensure transparency for process of critical review and knowledge transfer

Towards a richer model of deliberation dialogue : closure problem and change of circumstances

This research was partially supported by Social Sciences and Humanities Research Council of Canada Insight Grant 435-2012-0104. This research was also partially supported by the award made by the RCUK Digital Economy program to the dot.rural Digital Economy Hub at the University of Aberdeen; award ref. : EP/G066051/1. Further refinements of this work were supported by the SICSA PECE scheme.Models of deliberative dialogue are fundamental for developing autonomous systems that support human practical reasoning. The question discussed in this paper is whether existing models are able to capture the complexity and richness of natural deliberation. In real-world contexts, circumstances relevant to the decision can change rapidly. We reflect on today's leading model of deliberation dialogue and we propose an extension to capture how newly exchanged information about changing circumstances may shape the dialogue.Moreover, in natural deliberation, a dialogue may be successful even if a decision on what to do has not been made. A set of criteria is proposed to address the problem of when to close off the practical reasoning phase of dialogue. We discuss some measures for evaluating the success of a dialogue after closure and we present some initial efforts to introduce the new deliberation features within an existing model of agent dialogue. We believe that our extended model of dialogue may contribute to representing that richness of natural deliberative dialogue that is yet to be addressed in existing models of agent deliberation.Publisher PDFPeer reviewe

Vanadium(V) tetra-phenolate complexes: synthesis, structural studies and ethylene homo-(co-)polymerization capability

Reaction of α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-p-xylene (p-L¹H₄) with two equivalents of [VO(OR)₃] (R = nPr, tBu) in refluxing toluene afforded, after work-up, the complexes {[VO(OnPr)(THF)]₂ (μ-p-L¹)}·2(THF) (1·2(THF)) or {[VO(OtBu)]₂ (μ-p-L¹)}·2MeCN (2·2MeCN), respectively in moderate to good yield. A similar reaction using the meta pro-ligand, namely α,α,α′,α′-tetrakis(3,5-di-tert-butyl-2-hydroxyphenyl)-m-xylene (m-L²H₄) afforded the complex {[VO(OnPr)(THF)]₂ (μ-p-L²)} (3). Use of [V(Np-R¹C₆H₄)(tBuO)₃] (R¹ = Me, CF₃) with p-L¹H₄ led to the isolation of the oxo–imido complexes {[VO(tBuO)][V(Np-R¹C₆H₄) (tBuO)](μ-p-L¹)} (R¹ = Me, 4·CH2Cl₂; CF₃, 5·CH2Cl₂), whereas use of [V(Np-R¹C₆H₄)CL³] (R¹ = Me, CF₃) in combination with Et₃N/p-L¹H₄ or p-L¹Na₄ afforded the diimido complexes {[V(Np-MeC₆H₄)(THF)Cl]₂ (μ-p-L¹)}·4toluene (6·4toluene) or {[V(Np-CF₃C₆H₄)(THF)Cl]₂ (μ-p-L¹)} (7). For comparative studies, the complex [(VO)(μ-OnPr)L³]₂ (8) has also been prepared via the interaction of [VO(nPrO)₃] and 2-(α-(2-hydroxy-3,5-di-tert-butylphenyl)benzyl)-4,6-di-tert-butylphenol (L³H2). The crystal structures of 1·2THF, 2·2MeCN, 3, 4·CH2Cl₂, 5·CH2Cl₂, 6·4toluene·THF, 7 and 8 have been determined. Complexes 1–3 and 5–8 have been screened as pre-catalysts for the polymerization of ethylene in the presence of a variety of co-catalysts (with and without a re-activator), including DMAC (dimethylaluminium chloride), DEAC (diethylaluminium chloride), EADC (ethylaluminium dichloride) and EASC (ethylaluminium sesquichloride) at various temperatures and for the co-polymerization of ethylene with propylene; results are compared versus the benchmark catalyst [VO(OEt)Cl₂]. In some cases, activities as high as 243 400 g mmol⁻¹ V⁻¹ h⁻¹ (30.43 kgPE mmol V⁻¹ h⁻¹ bar⁻¹) were achievable, whilst it also proved possible to obtain higher molecular weight polymers (in comparable yields to the use of [VO(OEt)Cl₂]). In all cases with dimethylaluminium chloride (DMAC)/ethyltrichloroacetate (ETA) activation, the activities achieved surpassed those of the benchmark catalyst. In the case of the co-polymerization of ethylene with propylene, complexes 1–3 and 5–8 showed comparable or higher molecular weight than [VO(OEt)Cl₂] with comparable catalytic activities or higher in the case of the imido complexes 6 and 7

Quantum Electromagnetic Fluctuations in Inhomogeneous Dielectric Media

A new mathematical and computational technique for calculating quantum vacuum expectation values of energy and momentum densities associated with electromagnetic fields in bounded domains containing inhomogeneous media is discussed. This technique is illustrated by calculating the mode contributions to the difference in the vacuum force expectation between opposite ends of an inhomogeneous dielectric non-dispersive medium confined to a perfectly conducting rigid box.Comment: 7 pages, appeared in Proceedings of SPIE Conference on Quantum Optics (2011