Structural properties and quasiparticule energies of cubic SrO, MgO and SrTiO3

The structural properties and the band structures of the charge-transfer insulating oxides SrO, MgO and SrTiO3 are computed both within density functional theory in the local density approximation (LDA) and in the Hedin's GW scheme for self-energy corrections, by using a model dielectric function, which approximately includes local field and dynamical effects. The deep valence states are shifted by the GW method to higher binding energies, in very good agreement with photoemission spectra. Since in all of these oxides the direct gaps at high-symmetry points of the Brillouin zone may be very sensitive to the actual value of the lattice parameter a, already at the LDA level, self-energy corrections are computed both at the theoretical and the experimental a. For MgO and SrO, the values of the transition energies between the valence and the conduction bands are improved by GW corrections, while for SrTiO3 they are overestimated. The results are discussed in relation to the importance of local field effects and to the nature of the electronic states in these insulating oxides.Comment: 3 figures, accepted in J. Phys.: Condens. Matte

Full Sky Study of Diffuse Galactic Emission at Decimeter Wavelengths

A detailed knowledge of the Galactic radio continuum is of high interest for studies of the dynamics and structure of the Galaxy as well as for the problem of foreground removal in Cosmic Microwave Background measurements. In this work we present a full-sky study of the diffuse Galactic emission at frequencies of few GHz, where synchrotron radiation is by far the dominant component. We perform a detailed combined analysis of the extended surveys at 408, 1420 and 2326 MHz (by Haslam et al. 1982, Reich 1982, Reich & Reich, 1986 and Jonas et al. 1998, respectively). Using the technique applied by Schlegel et al. (1998) to the IRAS data, we produce destriped versions of the three maps. This allows us to construct a nearly-full-sky map of the spectral index and of the normalization factor with sub-degree angular resolution. The resulting distribution of the spectral indices has an average of beta = 2.695 and dispersion sigma_{beta} = 0.120. This is representative for the Galactic diffuse synchrotron emission, with only minor effects from free-free emission and point sources.Comment: 10 pages, 16 jpeg figures, accepted to Astronomy & Astrophysics, Comments and figure adde

Subjectivities in motion: Dichotomies in consumer engagements with self-tracking technologies

With the rise of self-tracking technologies (STT), self-quantification has become a popular digital consumption phenomenon. Despite recent academic interests, self-tracking practices remain poorly understood, in particular, little is known on how consumers engage with STT and how such behavioural trends produce new subjectivities. This paper adopts a Foucauldian perspective of self-surveillance to explore: how do subjectivities emerge from consumer interactions and engagements with self-tracking technologies? Data were collected from twenty participants using an ethnographic research design over six months consisting of semi-structured interviews and participant observation. The findings reveal two sets of dichotomies in the way consumers engage with STT, categorised as: ‘health and indulgence’ and ‘labour and leisure’. Through these dichotomies of self-surveillance, four subjectivities emerged: ‘redemptive self’, ‘awardee’, ‘loyal’ and ‘innovator’. Our study presents subjectivities as a continual process of (re)configuration of the self, as consumers move from one dichotomy to another. At the practical level, our findings offer novel approaches to segment consumers by reviewing the different contours of consumer behaviour in their interactions with STT

Away from home: how young Chinese consumers travel with global brands?

This interpretive study investigates how a group of young Chinese students consume global brands of American origins, in China and in the UK. More specifically, this research examines how meanings attached to global food brands travel abroad with consumers and investigates the relationship between brand consistency and brand meanings across national boundaries. Findings from a thematic analysis of focus group interviews conducted over a nine-month period, reveal that some brand meanings are context and culture specific (contextual meanings) while other meanings travel with consumers across borders (core meanings). Theoretically, this study shows how global brands provide a platform of structural meanings, ideas and practices that are global and globalising in themselves, allowing a degree of fluidity and adaptation in relation to the local context of consumption

Right Taste, Wrong Place’: Local Food Cultures, (Dis)identification and the Formation of Middle-class Identity

This article investigates how culinary taste contributes to the formation of middle class identity in a working class context in the UK. We explore practices of food consumption among a group of individuals working at a UK university located in a working class city. We find a rather limited and discrepant cosmopolitanism, in which culinary practices are evaluated in terms of those worth engaging in, and those not worth engaging in, based on their ‘user friendliness’ for cosmopolitan middle class dispositions. Depictions of the local food culture as lacking are also dominant, used as a negative ground against which these dispositions are hierarchically formulated. Here middle class culinary tastes seem to be driven by disengagement with the wrong sort of place and a relatively closed alignment with the ‘proper’ and the ‘safe’ rather than by any open creative individuality

Distribution of G-concurrence of random pure states

Average entanglement of random pure states of an N x N composite system is analyzed. We compute the average value of the determinant D of the reduced state, which forms an entanglement monotone. Calculating higher moments of the determinant we characterize the probability distribution P(D). Similar results are obtained for the rescaled N-th root of the determinant, called G-concurrence. We show that in the limit $N\to\infty$ this quantity becomes concentrated at a single point G=1/e. The position of the concentration point changes if one consider an arbitrary N x K bipartite system, in the joint limit $N,K\to\infty$, K/N fixed.Comment: RevTeX4, 11 pages, 4 Encapsuled PostScript figures - Introduced new results, Section II and V have been significantly improved - To appear on PR

Dynamic validation of the Planck/LFI thermal model

The Low Frequency Instrument (LFI) is an array of cryogenically cooled radiometers on board the Planck satellite, designed to measure the temperature and polarization anisotropies of the cosmic microwave backgrond (CMB) at 30, 44 and 70 GHz. The thermal requirements of the LFI, and in particular the stringent limits to acceptable thermal fluctuations in the 20 K focal plane, are a critical element to achieve the instrument scientific performance. Thermal tests were carried out as part of the on-ground calibration campaign at various stages of instrument integration. In this paper we describe the results and analysis of the tests on the LFI flight model (FM) performed at Thales Laboratories in Milan (Italy) during 2006, with the purpose of experimentally sampling the thermal transfer functions and consequently validating the numerical thermal model describing the dynamic response of the LFI focal plane. This model has been used extensively to assess the ability of LFI to achieve its scientific goals: its validation is therefore extremely important in the context of the Planck mission. Our analysis shows that the measured thermal properties of the instrument show a thermal damping level better than predicted, therefore further reducing the expected systematic effect induced in the LFI maps. We then propose an explanation of the increased damping in terms of non-ideal thermal contacts.Comment: Planck LFI technical papers published by JINST: http://www.iop.org/EJ/journal/-page=extra.proc5/1748-022

Effect of Fourier filters in removing periodic systematic effects from CMB data

We consider the application of high-pass Fourier filters to remove periodic systematic fluctuations from full-sky survey CMB datasets. We compare the filter performance with destriping codes commonly used to remove the effect of residual 1/f noise from timelines. As a realistic working case, we use simulations of the typical Planck scanning strategy and Planck Low Frequency Instrument noise performance, with spurious periodic fluctuations that mimic a typical thermal disturbance. We show that the application of Fourier high-pass filters in chunks always requires subsequent normalisation of induced offsets by means of destriping. For a complex signal containing all the astrophysical and instrumental components, the result obtained by applying filter and destriping in series is comparable to the result obtained by destriping only, which makes the usefulness of Fourier filters questionable for removing this kind of effects.Comment: 10 pages, 8 figures, published in Astronomy & Astrophysic