8,326 research outputs found

    Remarks on the Reeh-Schlieder property for higher spin free fields on curved spacetimes

    Full text link
    The existence of states enjoying a weak form of the Reeh-Schlieder property has been recently established on curved backgrounds and in the framework of locally covariant quantum field theory. Since only the example of a real scalar field has been discussed, we extend the analysis to the case of massive and massless free fields either of spin 1/2 or of spin 1. In the process, it is also shown that both the vector potential and the Proca field can be described as a locally covariant quantum field theory.Comment: 28 pages, references and remarks added, typos correcte

    Towards an expanded model of litigation

    Get PDF
    Introduction: The call for contributions for this workshop describes the important new challenges for the legal search community this domain brings. Rather than just understanding the challenges this domain poses in terms of their technical properties, we would like to suggest that understanding these challenges as socio-technical challenges will be important. That is, as well as calling for research on a technical level to address these challenges we are also calling for work to understand the social practices of those involved in e-discovery (ED) and related legal work. A particularly interesting feature of this field is that it is likely that search technologies will (at least semi-)automate responsiveness review in the relatively near term and this will change the way that the work is organised and done in many ways – offering new possibilities for new ways of organising the work. As well as designing those technologies for automating responsiveness review we need to be envisioning how the work will be done in the future, how these technologies will impact the organisation of the case and so on. In this position paper we therefore outline the importance of understanding the wider social context of ED when designing tools and technologies to support and change the work. We would like to reinforce and expand on Conrad’s call for IR researchers to understand just what ED entails [2], include the stages that come both before and after core retrieval activities. The importance of considering the social aspects of work in the design of the technology has been established for some time. Ushering in this ‘turn to the social,’ and focusing on interface design, Gentner and Grudin [4] described how the GUI has already changed from an interface for engineers, representing the engineering model of the machine to one that supported single ‘everyman’ users (based on ideas from psychology). From then onwards the interface has evolved to support groups of users, taking into account the social and organisational contexts of use. This has particular resonance for the design of ED technologies: during ED in particular and the wider legal process there are often many lawyers involved – reviewing documents, determining issues, etc. Even if the way that their work is organised currently is not seen as collaborative in the traditional sense – with individual lawyers working on individual document sets to review them - their work needs to be coordinated and it seems likely that their work could be enhanced by, for example, knowledge of what their colleagues had found, how the case was shaping up, new key terms and facts turned up and so on. Work is often modelled for the purposes of design using process models, but this misses out on the richness and variety actually found when one examines how the work is carried out [3]. Technologies which strictly enforce the process models can often hinder the work, or end up being worked around as was the case with workflow systems since people interpret processes very flexibly to get the work done ([1], [3]). Other studies in other fields have found similar problems when systems are designed on for example cognitive models of how the work is done; they often do not take into account the situated nature of the work and thus they can be very difficult to use [5]. We believe, like [2], that a clear understanding of the social practices of ED is vital for the creation of high-quality, meaningful tools and technologies. We furthermore propose that work practice studies, to be used in combination with other methods, are a central part of getting the detailed understanding of the work practices central to designing useful and intelligent tools. Work practice studies would involve ethnographies, consisting primarily of observation, undertaken of practitioners engaging in the work of ED

    Examining bushfire policy in action: Preparedness and behaviour in the 2009 Black Saturday fires

    Get PDF
    This is the author accepted manuscript. The final version is available from the publisher via the DOI in this record.An important part of reducing the risk of disaster is the preparedness of the people at risk. Australian bushfire authorities have policies and publicity about what households should do to be prepared - which include knowledge about fire risk, awareness of one's own risk, taking specific steps to reduce risk including having an emergency plan. Yet, there is sparse empirical evidence about the link between preparedness and actual behaviour in the face of a major disaster.The authors had an opportunity to examine the circumstances surrounding the 172 civilian fatalities which occurred in the 2009 Victorian 'Black Saturday' bushfires, through the examination of a detailed fatality dataset compiled by the Victorian Bushfires Royal Commission. This dataset allows detailed examination of Victorian bushfire safety policy ('Stay or go') in action on a day of extreme fire danger: from preparedness (both before and on the day of the fire) to behaviour on the day of the fire itself.This analysis presents three overarching findings. First, some aspects of 'Stay or go' appear to be supported: being well-prepared to evacuate remains the safest option in a bushfire; sheltering passively is very dangerous. Second, successful implementation of 'Stay or go' depends on a multitude of factors, which can challenge even the most capable householders. Third, events like Black Saturday challenge the 'Stay or go' approach, and indicate the need for a different approach on extreme fire danger days. We conclude by reflecting on the findings from this research in terms of the most recent changes to bushfire policy in Victoria.The project was funded by the Victorian Bushfires Royal Commission through the Bushfire Cooperative Research Centre. The Commission was involved in the project in an oversight capacity, in particular to ensure that strict confidence was maintained, and that conflicts of interest were avoided. Writing of this paper was supported through Saffron O’Neill’s ESRC Fellowship (S/K001175/1)

    Three water sites in upper mantle olivine and the role of titanium in the water weakening mechanism

    Get PDF
    Infrared spectroscopy on synthetic olivines has established that there are at least four different mechanisms by which hydrogen is incorporated into the crystal structure. Two mechanisms occur in the system MgO-SiO2-H2O associated with silicon and magnesium vacancies, respectively. A third mechanism is associated with trivalent cation substitution, commonly Fe3+ in natural olivine, while the fourth mechanism, which is the one most prevalent in natural olivines from the spinel-peridotite facies of the Earth’s upper mantle, is associated with Ti4+ [Berry et al., 2005]. Here first principles calculations based on density functional theory are used to derive the structure and relative energies of the two defects in the pure MgO-SiO2-H2O system, and possible hydrogen-bearing and hydrogen-free point defects in Ti4+-doped forsterite. Calculated structures are used to compare the predicted orientation of the O-H bonds with the experimentally determined polarization. The energies are used to discuss how different regimes of chemical environment, temperature (T), pressure (P), and both water content and water fugacity ( fH2O), impact on which of the different hydroxyl substitution mechanisms are thermodynamically stable. We find that given the presence of Ti impurities, the most stable mechanism involves the formation of silicon vacancies containing two protons charge balanced by a Ti4+ cation occupying an adjacent octahedral site. This mechanism leads to the water-mediated formation of silicon vacancies. As silicon is known to be the most slowly diffusing species in olivine, this provides a credible explanation of the observed water weakening effect in olivine

    In-Chain Tunneling Through Charge-Density Wave Nanoconstrictions and Break-Junctions

    Full text link
    We have fabricated longitudinal nanoconstrictions in the charge-density wave conductor (CDW) NbSe3_{3} using a focused ion beam and using a mechanically controlled break-junction technique. Conductance peaks are observed below the TP1_{P1}=145=145 K and TP2_{P2}=59=59 K CDW transitions, which correspond closely with previous values of the full CDW gaps 2Δ12\Delta_{1} and 2Δ22\Delta_{2} obtained from photo-emission. These results can be explained by assuming CDW-CDW tunneling in the presence of an energy gap corrugation ϵ2\epsilon_{2} comparable to Δ2\Delta_{2}, which eliminates expected peak at Δ1+Δ2\Delta_{1}+\Delta_{2}. The nanometer length-scales our experiments imply indicate that an alternative explanation based on tunneling through back-to-back CDW-normal junctions is unlikely.Comment: 5 pages, 3 figures, submitted to physical review letter

    No time machines in classical general relativity

    Get PDF
    Irrespective of local conditions imposed on the metric, any extendible spacetime U has a maximal extension containing no closed causal curves outside the chronological past of U. We prove this fact and interpret it as impossibility (in classical general relativity) of the time machines, insofar as the latter are defined to be causality-violating regions created by human beings (as opposed to those appearing spontaneously).Comment: A corrigendum (to be published in CQG) has been added to correct an important mistake in the definition of localit

    Demography and disorders of the French Bulldog population under primary veterinary care in the UK in 2013

    Get PDF
    Abstract Background Despite its Gallic name, the French Bulldog is a breed of both British and French origin that was first recognised by The Kennel Club in 1906. The French Bulldog has demonstrated recent rapid rises in Kennel Club registrations and is now (2017) the second most commonly registered pedigree breed in the UK. However, the breed has been reported to be predisposed to several disorders including ocular, respiratory, neurological and dermatological problems. The VetCompass™ Programme collates de-identified clinical data from primary-care veterinary practices in the UK for epidemiological research. Using VetCompass™ clinical data, this study aimed to characterise the demography and common disorders of the general population of French Bulldogs under veterinary care in the UK. Results French Bulldogs comprised 2228 (0.49%) of 445,557 study dogs under veterinary care during 2013. Annual proportional birth rates showed that the proportional ownership of French Bulldog puppies rose steeply from 0.02% of the annual birth cohort attending VetCompass™ practices in 2003 to 1.46% in 2013. The median age of the French Bulldogs overall was 1.3 years (IQR 0.6–2.5, range 0.0–13.0). The most common colours of French Bulldogs were brindle (solid or main) (32.36%) and fawn (solid or main) (29.9%). Of the 2228 French Bulldogs under veterinary care during 2013, 1612 (72.4%) had at least one disorder recorded. The most prevalent fine-level precision disorders recorded were otitis externa (14.0%, 95% CI: 12.6–15.5), diarrhoea (7.5%, 95% CI: 6.4–8.7), conjunctivitis (3.2%, 95% CI: 2.5–4.0), nails overlong (3.1%, 95% CI% 2.4–3.9) and skin fold dermatitis (3.0%, 95% CI% 2.3–3.8). The most prevalent disorder groups were cutaneous (17.9%, 95% CI: 16.3–19.6), enteropathy (16.7%, 95% CI: 15.2–18.3), aural (16.3%, 95% CI: 14.8–17.9), upper respiratory tract (12.7%, 95% CI: 11.3–14.1) and ophthalmological (10.5%, 95% CI: 9.3–11.9). Conclusions Ownership of French Bulldogs in the UK is rising steeply. This means that the disorder profiles reported in this study reflect a current young UK population and are likely to shift as this cohort ages. Otitis externa, diarrhoea and conjunctivitis were the most common disorders in French Bulldogs. Identification of health priorities based on VetCompass™ data can support evidence–based reforms to improve health and welfare within the breed
    • …
    corecore