The Remarkable Be Star HD110432

HD110432 has gained considerable attention because it is a hard, variable X-ray source similar to gamma Cas. From time-serial echelle data obtained over two weeks during 2005 January and February, we find several remarkable characteristics in the star's optical spectrum. The line profiles show rapid variations on some nights which can be most likely be attributed to irregularly occurring and short-lived migrating subfeatures. Such features have only been observed to date in gamma Cas and AB Dor, two stars for which it is believed magnetic fields force circumstellar clouds to corotate over the stellar surface. The star's optical spectrum also exhibits a number of mainly FeII and HeI emission features with profiles typical of an optically thin disk viewed edge-on. Using spectral synthesis techniques, we find that its temperature is 9800K +/-300K, that its projected area is a remarkably large 100 stellar areas, and its emitting volume resides at a distance of 1 AU from the star. We also find that the star's absorption profiles extend to +/-1000 km/s, a fact which we cannot explain. Otherwise, HD110432 and gamma Cas share similarly peculiar X-ray and optical characteristics such as high X-ray temperature, erratic X-ray variability on timescales of a few hours, optical emission lines, and submigrating features in optical line profiles. Because of these similarities, we suggest that this star is a new member of a select class of "gamma Cas analogs."Comment: 31 pages, 9 figures, accepted by ApJ (3/20/06

Stress-energy tensor in the Bel-Szekeres space-time

In a recent work an approximation procedure was introduced to calculate the vacuum expectation value of the stress-energy tensor for a conformal massless scalar field in the classical background determined by a particular colliding plane wave space-time. This approximation procedure consists in appropriately modifying the space-time geometry throughout the causal past of the collision center. This modification in the geometry allows to simplify the boundary conditions involved in the calculation of the Hadamard function for the quantum state which represents the vacuum in the flat region before the arrival of the waves. In the present work this approximation procedure is applied to the non-singular Bel-Szekeres solution, which describes the head on collision of two electromagnetic plane waves. It is shown that the stress-energy tensor is unbounded as the killing-Cauchy horizon of the interaction is approached and its behavior coincides with a previous calculation in another example of non-singular colliding plane wave space-time.Comment: 17 pages, LaTex file, 2 PostScript figure

Closing in on the picture : analyzing interactions in video recordings

This paper provides a detailed account of the processing and analysing of data, obtained through video recording during reflective practitioner research. It sets out five stages in the analysis of video recordings of classroom interactions during a series of educational drama lessons: from decisions relating to the selection of data for close analysis, to the seeking of themes, and finally to the presentation of conclusions. The researcher adapted and synthesised several processes derived from discourse analysis (Wells, 2001; Spiers, 2004; Gee, 2005) to produce a range of instruments for use in transcription and analysis of verbal and non-verbal discourse. These include: a simple transcription key; classifications for verbal and non-verbal discourse; and a template for a transcription and analysis matrix

Dynamics of a ferromagnetic domain wall: avalanches, depinning transition and the Barkhausen effect

We study the dynamics of a ferromagnetic domain wall driven by an external magnetic field through a disordered medium. The avalanche-like motion of the domain walls between pinned configurations produces a noise known as the Barkhausen effect. We discuss experimental results on soft ferromagnetic materials, with reference to the domain structure and the sample geometry, and report Barkhausen noise measurements on Fe$_{21}$Co$_{64}$B$_{15}$ amorphous alloy. We construct an equation of motion for a flexible domain wall, which displays a depinning transition as the field is increased. The long-range dipolar interactions are shown to set the upper critical dimension to $d_c=3$, which implies that mean-field exponents (with possible logarithmic correction) are expected to describe the Barkhausen effect. We introduce a mean-field infinite-range model and show that it is equivalent to a previously introduced single-degree-of-freedom model, known to reproduce several experimental results. We numerically simulate the equation in $d=3$, confirming the theoretical predictions. We compute the avalanche distributions as a function of the field driving rate and the intensity of the demagnetizing field. The scaling exponents change linearly with the driving rate, while the cutoff of the distribution is determined by the demagnetizing field, in remarkable agreement with experiments.Comment: 17 RevTeX pages, 19 embedded ps figures + 1 extra figure, submitted to Phys. Rev.

Quantum Collective Creep: a Quasiclassical Langevin Equation Approach

The dynamics of an elastic medium driven through a random medium by a small applied force is investigated in the low-temperature limit where quantum fluctuations dominate. The motion proceeds via tunneling of segments of the manifold through barriers whose size grows with decreasing driving force $f$. In the limit of small drive, at zero-temperature the average velocity has the form $v\propto\exp[-{\rm const.}/\hbar^{\alpha} f^{\mu}]$. For strongly dissipative dynamics, there is a wide range of forces where the dissipation dominates and the velocity--force characteristics takes the form $v\propto\exp[-S(f)/\hbar]$, with $S(f)\propto 1/ f^{(d+2\zeta)/(2-\zeta)}$ the action for a typical tunneling event, the force dependence being determined by the roughness exponent $\zeta$ of the $d$-dimensional manifold. This result agrees with the one obtained via simple scaling considerations. Surprisingly, for asymptotically low forces or for the case when the massive dynamics is dominant, the resulting quantum creep law is {\it not} of the usual form with a rate proportional to $\exp[-S(f)/\hbar]$; rather we find $v\propto \exp\{-[S(f)/\hbar]^2\}$ corresponding to $\alpha=2$ and $\mu= 2(d+2\zeta-1)/(2-\zeta)$, with $\mu/2$ the naive scaling exponent for massive dynamics. Our analysis is based on the quasi-classical Langevin approximation with a noise obeying the quantum fluctuation--dissipation theorem. The many space and time scales involved in the dynamics are treated via a functional renormalization group analysis related to that used previously to treat the classical dynamics of such systems. Various potential difficulties with these approaches to the multi-scale dynamics -- both classical and quantum -- are raised and questions about the validity of the results are discussed.Comment: RevTeX, 30 pages, 8 figures inserte

Highly Anisotropic Transport in the Integer Quantum Hall Effect

At very large tilt of the magnetic (B) field with respect to the plane of a two-dimensional electron system the transport in the integer quantum Hall regime at $\nu$ = 4, 6, and 8 becomes strongly anisotropic. At these filling factors the usual {\em deep minima} in the magneto-resistance occur for the current flowing {\em perpendicular} to the in-plane B field direction but develop into {\em strong maxima} for the current flowing {\em parallel} to the in-plane B field. The origin of this anisotropy is unknown but resembles the recently observed anisotropy at half-filled Landau levels.Comment: 4 pages, 4 figure

Eurozone Membership and Foreign Direct Investment

Our aim in this chapter is to estimate the effects of European Monetary Union (EMU) membership on foreign direct investment (FDI). Previous literature on the cross-border impact of a common currency have concentrated on international trade effects. Our analysis is based on the gravity model, which has been successfully applied to explain most forms of bilateral cross-border flows. We estimate a structural gravity model using data for 34 OECD countries between 1985 and 2013 for bilateral FDI. We use a variety of econometric techniques to ensure the robustness of our findings including stock as well as flow measures of FDI and addressing selection issues. Our estimates of the impact of EMU underlines the role of FDI as a channel for benefits from deep economic integration between countries. The effect of EMU membership on FDI is estimated to be significant and positive, at around 130%

Yorkshire Lung Screening Trial (YLST): protocol for a randomised controlled trial to evaluate invitation to community-based low-dose CT screening for lung cancer versus usual care in a targeted population at risk

Introduction: Lung cancer is the world’s leading cause of cancer death. Low-dose computed tomography (LDCT) screening reduced lung cancer mortality by 20% in the US National Lung Screening Trial. Here, we present the Yorkshire Lung Screening Trial (YLST), which will address key questions of relevance for screening implementation. / Methods and analysis: Using a single-consent Zelen’s design, ever-smokers aged 55–80 years registered with a general practice in Leeds will be randomised (1:1) to invitation to a telephone-based risk-assessment for a Lung Health Check or to usual care. The anticipated number randomised by household is 62 980 individuals. Responders at high risk will be invited for LDCT scanning for lung cancer on a mobile van in the community. There will be two rounds of screening at an interval of 2 years. Primary objectives are (1) measure participation rates, (2) compare the performance of PLCOM2012 (threshold ≥1.51%), Liverpool Lung Project (V.2) (threshold ≥5%) and US Preventive Services Task Force eligibility criteria for screening population selection and (3) assess lung cancer outcomes in the intervention and usual care arms. Secondary evaluations include health economics, quality of life, smoking rates according to intervention arm, screening programme performance with ancillary biomarker and smoking cessation studies. / Ethics and dissemination: The study has been approved by the Greater Manchester West research ethics committee (18-NW-0012) and the Health Research Authority following review by the Confidentiality Advisory Group. The results will be disseminated through publication in peer-reviewed scientific journals, presentation at conferences and on the YLST website. / Trial registration numbers: ISRCTN42704678 and NCT03750110

Facial expressions depicting compassionate and critical emotions: the development and validation of a new emotional face stimulus set

Attachment with altruistic others requires the ability to appropriately process affiliative and kind facial cues. Yet there is no stimulus set available to investigate such processes. Here, we developed a stimulus set depicting compassionate and critical facial expressions, and validated its effectiveness using well-established visual-probe methodology. In Study 1, 62 participants rated photographs of actors displaying compassionate/kind and critical faces on strength of emotion type. This produced a new stimulus set based on N = 31 actors, whose facial expressions were reliably distinguished as compassionate, critical and neutral. In Study 2, 70 participants completed a visual-probe task measuring attentional orientation to critical and compassionate/kind faces. This revealed that participants lower in self-criticism demonstrated enhanced attention to compassionate/kind faces whereas those higher in self-criticism showed no bias. To sum, the new stimulus set produced interpretable findings using visual-probe methodology and is the first to include higher order, complex positive affect displays

Apparent Alkyl Transfer and Phenazine Formation via an Aryne Intermediate

Treatment of chlorotriaryl derivatives 3a and 3d or fluorotriaryl derivatives 3b and 3e with potassium diisopropylamide afforded alkyl-shifted phenazine derivatives 5a/5b, rather than the expected 9-membered triazaorthocyclophane 2a. The phenazine derivatives were isolated in 78–98% yield depending on the halogen and alkyl group present. In the absence of the halogen (chloro or fluoro), the apparent alkyl shift proceeds more slowly and cannot proceed via the intermediacy of the aryne intermediate. Mechanistic possibilities include intramolecular nucleophilic attack on an aryne intermediate leading to a zwitterionic intermediate and alkyl transfer via a 5-endo-tet process, or via a Smiles rearrangement