Decoherence of Macroscopic Closed Systems within Newtonian Quantum Gravity

A theory recently proposed by the author aims to explain decoherence and the thermodynamical behaviour of closed systems within a conservative, unitary, framework for quantum gravity by assuming that the operators tied to the gravitational degrees of freedom are unobservable and equating physical entropy with matter-gravity entanglement entropy. Here we obtain preliminary results on the extent of decoherence this theory predicts. We treat first a static state which, if one were to ignore quantum gravitational effects, would be a quantum superposition of two spatially displaced states of a single classically well describable ball of uniform mass density in empty space. Estimating the quantum gravitational effects on this system within a simple Newtonian approximation, we obtain formulae which predict e.g. that as long as the mass of the ball is considerably larger than the Planck mass, such a would-be-coherent static superposition will actually be decohered whenever the separation of the centres of mass of the two ball-states excedes a small fraction (which decreases as the mass of the ball increases) of the ball radius. We then obtain a formula for the quantum gravitational correction to the would-be-pure density matrix of a non-relativistic many-body Schroedinger wave function and argue that this formula predicts decoherence between configurations which differ (at least) in the "relocation" of a cluster of particles of Planck mass. We estimate the entropy of some simple model closed systems, finding a tendency for it to increase with "matter-clumping" suggestive of a link with existing phenomenological discussions of cosmological entropy increase.Comment: 11 pages, plain TeX, no figures. Accepted for publication as a "Letter to the Editor" in "Classical and Quantum Gravity

Exit Polling in Canada: An Experiment

Although exit polling has not been used to study Canadian elections before, such polls have methodological features that make them a potentially useful complement to data collected through more conventional designs. This paper reports on an experiment with exit polling in one constituency in the 2003 Ontario provincial election. Using student volunteers, a research team at Wilfrid Laurier University conducted an exit poll in the bellwether constituency of Kitchener Centre to assess the feasibility of mounting this kind of study on a broader scale. The experiment was successful in a number of respects. It produced a sample of 653 voters that broadly reflected the partisan character of the constituency, and which can hence be used to shed light on patterns of vote-switching and voter motivations in that constituency. It also yielded insights about best practices in mounting an exit poll in the Ontario context, as well as about the potential for using wireless communication devices to transmit respondent data from the field. The researchers conclude that exit polling on a limited basis (selected constituencies) is feasible, but the costs and logistics associated with this methodology make a province-wide or country-wide study unsupportable at present

The relevance of ‘competence’ for enhancing or limiting children’s participation: unpicking conceptual confusion

Recent debates about children’s participation rights, formulated in the UN Convention on the Rights of the Child, primarily focus on ‘effectiveness’ of implementation. However, children’s participation remains problematic, its limited impact on adult power in decision-making or on the nature of decisions made persists, and reservations about children’s competence as participants are implicated in both. In respect of this, we analysed conceptualisations of competence in 67 articles, published between 2007 and 2017 in six childhood studies’ journals, where ‘competence’ and its variations appear in the abstract. Although competence is rarely defined, conceptualisations were wide-ranging, covering competence as skills, as compliance with adult views, and as a trope signalling the field of childhood studies. As a result of our findings, we argue that epistemological clarity is vital for this concept to be useful regarding children’s participation and that attention must be paid to the different kinds of competence relevant for ‘effective’ participation

Asymptotics of the mean-field Heisenberg model

We consider the mean-field classical Heisenberg model and obtain detailed information about the total spin of the system by studying the model on a complete graph and sending the number of vertices to infinity. In particular, we obtain Cramer- and Sanov-type large deviations principles for the total spin and the empirical spin distribution and demonstrate a second-order phase transition in the Gibbs measures. We also study the asymptotics of the total spin throughout the phase transition using Stein's method, proving central limit theorems in the sub- and supercritical phases and a nonnormal limit theorem at the critical temperature.Comment: 44 page

Identification and characterisation of enteroaggregative Escherichia coli subtypes associated with human disease

Enteroaggregative E. coli (EAEC) are a major cause of diarrhoea worldwide. Due to their heterogeneity and carriage in healthy individuals, identification of diagnostic virulence markers for pathogenic strains has been difficult. In this study, we have determined phenotypic and genotypic differences between EAEC strains of sequence types (STs) epidemiologically associated with asymptomatic carriage (ST31) and diarrhoeal disease (ST40). ST40 strains demonstrated significantly enhanced intestinal adherence, biofilm formation, and pro-inflammatory interleukin-8 secretion compared with ST31 isolates. This was independent of whether strains were derived from diarrhoea patients or healthy controls. Whole genome sequencing revealed differences in putative virulence genes encoding aggregative adherence fimbriae, E. coli common pilus, flagellin and EAEC heat-stable enterotoxin 1. Our results indicate that ST40 strains have a higher intrinsic potential of human pathogenesis due to a specific combination of virulence-related factors which promote host cell colonization and inflammation. These findings may contribute to the development of genotypic and/or phenotypic markers for EAEC strains of high virulence

Viewers base estimates of face matching accuracy on their own familiarity: Explaining the photo-ID paradox

Matching two different images of a face is a very easy task for familiar viewers, but much harder for unfamiliar viewers. Despite this, use of photo-ID is widespread, and people appear not to know how unreliable it is. We present a series of experiments investigating bias both when performing a matching task and when predicting other people’s performance. Participants saw pairs of faces and were asked to make a same/different judgement, after which they were asked to predict how well other people, unfamiliar with these faces, would perform. In four experiments we show different groups of participants familiar and unfamiliar faces, manipulating this in different ways: celebrities in experiments 1 to 3 and personally familiar faces in experiment 4. The results consistently show that people match images of familiar faces more accurately than unfamiliar faces. However, people also reliably predict that the faces they themselves know will be more accurately matched by different viewers. This bias is discussed in the context of current theoretical debates about face recognition, and we suggest that it may underlie the continued use of photo-ID, despite the availability of evidence about its unreliability

Magnetic states at the surface of alpha Fe2O3 thin films doped with Ti, Zn, or Sn

The spin states at the surface of epitaxial thin films of hematite, both undoped and doped with 1% Ti, Sn or Zn, respectively, were probed with x-ray magnetic linear dichroism (XMLD) spectroscopy. Morin transitions were observed for the undoped (T_M~200 K) and Sn-doped (T_M~300 K) cases, while Zn and Ti-doped samples were always in the high and low temperature phases, respectively. In contrast to what has been reported for bulk hematite doped with the tetravalent ions Sn4+ and Ti4+, for which T_M dramatically decreases, these dopants substantially increase T_M in thin films, far exceeding the bulk values. The normalized Fe LII-edge dichroism for T<T_M does not strongly depend on doping or temperature, except for an apparent increase of the peak amplitudes for T<100 K. We observed magnetic field-induced inversions of the dichroism peaks. By applying a magnetic field of 6.5 T on the Ti-doped sample, a transition into the T>T_M state was achieved. The temperature dependence of the critical field for the Sn-doped sample was characterized in detail. It was demonstrated the sample-to-sample variations of the Fe LIII-edge spectra were, for the most part, determined solely by the spin orientation state. Calculations of the polarization-depedent spectra based on a spin-multiplet model were in reasonable agreement with the experiment and showed a mixed excitation character of the peak structures.Comment: 8 pages, 8 figure

A reanalysis of the luminosities of clusters of galaxies in the EMSS sample with 0.3 < z < 0.6

The X-ray luminosities of the Einstein Extended Medium Sensitivity Survey (EMSS) clusters of galaxies with redshifts 0.3<z<0.6 are remeasured using ROSAT PSPC data. It is found that the new luminosities are on average 1.18 +/- 0.08 times higher than previously measured but that this ratio depends strongly on the X-ray core radii we measure. For the clusters with small core radii, in general we confirm the EMSS luminosities, but for clusters with core radii >250 kpc (the constant value assumed in the EMSS), the new luminosities are 2.2 +/- 0.15 times the previous measurements. The X-ray luminosity function (XLF) at 0.3<z<0.6 is recalculated and is found to be consistent with the local XLF. The constraints on the updated properties of the 0.3<z<0.6 EMSS sample, including a comparison with the number of clusters predicted from local XLFs, indicate that the space density of luminous, massive clusters has either not evolved or has increased by a small factor ~2 since z=0.4. The implications of this result are discussed in terms of constraints on the cosmological parameter Omega_0.Comment: 12 pages, 7 figures. Accepted for publication in MNRA

Quantum singularity of Levi-Civita spacetimes

Quantum singularities in general relativistic spacetimes are determined by the behavior of quantum test particles. A static spacetime is quantum mechanically singular if the spatial portion of the wave operator is not essentially self-adjoint. Here Weyl's limit point-limit circle criterion is used to determine whether a wave operator is essentially self-adjoint. This test is then applied to scalar wave packets in Levi-Civita spacetimes to help elucidate the physical properties of the spacetimes in terms of their metric parameters

A feasibility study for the reporting of cervical large loop excisions of the transformation zone (LLETZ) biopsies by consultant biomedical scientists in the UK

A thesis submitted in partial fulfilment of the requirements of the University of Wolverhampton for the degree of Doctor of Biomedical Science.Objective – A previous pilot study had shown that there was potential to extend the roles of advanced biomedical scientist practitioner (ABMSPs) now referred to as Consultant Biomedical Scientists (BMS) to report the histology of large loop excision biopsies of the cervical transformation zone (LLETZ) within the NHS Cervical Screening Programme (NHSCSP). Methods - 157 consecutive LLETZ specimens reported by four experienced Gynae-specialist Consultant Histopathologists at Sheffield Teaching Hospitals NHS Foundation Trust, were also reported by six Consultant BMS, and compared against the final issued report. Neoplastic abnormalities were reported to NHSCSP standards as well as the Bethesda system. Completeness of excision and histological features associated with the presence of human papillomavirus (HPV) infection were also assessed. The reporting of HPV is part of the proforma for reporting cervical samples, it does not affect the patient management but allows for correlation with the cervical cytology report and hence was included as part of the study. Results - There was overall good inter-observer agreement for both the three tier and two tier system of grading squamous lesions plus good agreement for glandular and invasive carcinomas identified by the Consultant BMS. There was variable inter-observer agreement for the completeness of the excision of the margins and the presence of HPV. Conclusions - This report provides evidence that suitably experienced Consultant BMS can be ‘fast-tracked’ through an approved training programme of selected specimens to meet the needs of the Histopathology service that is facing a chronic shortage of Histopathologists in a timely manner and provide a cost-effective solution