Subjective Logic and Arguing with Evidence

Peer reviewedPreprin

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

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

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

Numerical Regularization of Electromagnetic Quantum Fluctuations in Inhomogeneous Dielectric Media

Electromagnetic Casimir stresses are of relevance to many technologies based on mesoscopic devices such as MEMS embedded in dielectric media, Casimir induced friction in nano-machinery, micro-fluidics and molecular electronics. Computation of such stresses based on cavity QED generally require numerical analysis based on a regularization process. A new scheme is described that has the potential for wide applicability to systems involving realistic inhomogeneous media. From a knowledge of the spectrum of the stationary modes of the electromagnetic field the scheme is illustrated by estimating numerically the Casimir stress on opposite faces of a pair of perfectly conducting planes separated by a vacuum and the change in this result when the region between the plates is filled with an incompressible inhomogeneous non-dispersive dielectric.Comment: 5 pages, 2 figures, submitted to PR

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

Reaction of the ligand 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(-p-L1)}·2(THF) (1·2(THF)) or {[VO(OtBu)]2(-p-L1)}·2MeCN (2·2MeCN), respectively in moderate to good yield. A similar reaction using the meta 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(-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)](-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(-p-L1)}·4toluene (6·4toluene) or {[V(Np-CF3C6H4)(THF)Cl]2(-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/mmolV.h (30.43 Kg PE/mmolV.h.bar) 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

Diagnosing the accretion flow in ultraluminous X-ray sources using soft X-ray atomic features

The lack of unambiguous detections of atomic features in the X-ray spectra of ultraluminous X-ray sources (ULXs) has proven a hindrance in diagnosing the nature of the accretion flow. The possible association of spectral residuals at soft energies with atomic features seen in absorption and/or emission and potentially broadened by velocity dispersion could therefore hold the key to understanding much about these enigmatic sources. Here we show for the first time that such residuals are seen in several sources and appear extremely similar in shape, implying a common origin. Via simple arguments we assert that emission from extreme colliding winds, absorption in a shell of material associated with the ULX nebula and thermal plasma emission associated with star formation are all highly unlikely to provide an origin. Whilst CCD spectra lack the energy resolution necessary to directly determine the nature of the features (i.e. formed of a complex of narrow lines or intrinsically broad lines), studying the evolution of the residuals with underlying spectral shape allows for an important, indirect test for their origin. The ULX NGC 1313 X-1 provides the best opportunity to perform such a test due to the dynamic range in spectral hardness provided by archival observations. We show through highly simplified spectral modelling that the strength of the features (in either absorption or emission) appears to anticorrelate with spectral hardness, which would rule out an origin via reflection of a primary continuum and instead supports a picture of atomic transitions in a wind or nearby material associated with such an outflow

The ‘heritagisation’ of the British seaside resort: The rise of the ‘old penny’ arcade.

Amusement arcades have long been a key component of the British seaside resort. For almost a century, they enjoyed popularity and success and became established as a quintessential feature of the British seaside holiday. However, the advent of home-based video games along with recent gambling legislation has led to a decline of the seaside amusement arcade sector. Arcades gained a reputation as unsavoury places and their appearance and fortunes often mirrored those of the resorts in which they were located. However, over the past decade, a new variant of the seaside amusement arcade has appeared, featuring mechanical machines working on pre-decimal currency. Such ‘old penny arcades’ frequently describe themselves as museums or heritage centres and they offer an experience based on a nostalgic affection for the ‘traditional’ seaside holiday. They have appeared in the context of an increasing interest in the heritage of the British seaside resort and constitute one element of the ‘heritagisation’ of such resorts. This paper argues that such arcades can be important elements of strategies to reposition and rebrand resorts for the heritage tourism market

More than sense of place? Exploring the emotional dimension of rural tourism experiences

It is widely suggested that participation in rural tourism is underpinned by a sense of rural place or “rurality”. However, although nature and the countryside have long been recognised as a source of spiritual or emotional fulfilment, few have explored the extent to which tourism, itself often claimed to be a sacred experience, offers an emotional/spiritual dimension in the rural context. This paper addresses that literature gap. Using in-depth interviews with rural tourists in the English Lake District, it explores the extent to which, within respondents’ individual understanding of spirituality, a relationship exists between sense of place and deeper, emotional experiences and, especially, whether participation in rural tourism may induce spiritual or emotional responses. The research revealed that all respondents felt a strong attachment to the Lake District; similarly, and irrespective of their openness to spirituality, engaging in rural tourism activities resulted in highly emotive experiences for all respondents, the description/interpretation of such experiences being determined by individual “beliefs”. However, sense of place was not a prerequisite to emotional or spiritual experiences. Being in and engaging with the landscape � effectively becoming part of it � especially through physical activity is fundamental to emotional responses

Karst of the Driftless Area of Jo Daviess County, Illinois

Ope