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

Static dielectric response and Born effective charge of BN nanotubes from {\it ab initio} finite electric field calculations

{\it Ab initio} investigations of the full static dielectric response and Born effective charge of BN nanotubes (BN-NTs) have been performed for the first time using finite electric field method. It is found that the ionic contribution to the static dielectric response of BN-NTs is substantial and also that a pronounced chirality-dependent oscillation is superimposed on the otherwise linear relation between the longitudinal electric polarizability and the tube diameter ($D$), as for a thin dielectric cylinderical shell. In contrast, the transverse dielectric response of the BN-NTs resemble the behavior of a thin (non-ideal) conducting cylindrical shell of a diameter of $D+4$\AA$$, with a screening factor of 2 for the inner electric field. The medium principal component $Z_y^*$ of the Born effective charge corresponding to the transverse atomic displacement tangential to the BN-NT surface, has a pronounced $D$-dependence (but independent of chirality), while the large longitudinal component $Z_z^*$ exhibits a clear chirality dependence (but nearly $D$-independent), suggesting a powerful way to characterize the diameter and chirality of a BN-NT.Comment: submitted to PR

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

Huge excitonic effects in layered hexagonal boron nitride

The calculated quasiparticle band structure of bulk hexagonal boron nitride using the all-electron GW approximation shows that this compound is an indirect-band-gap semiconductor. The solution of the Bethe-Salpeter equation for the electron-hole two-particle Green function has been used to compute its optical spectra and the results are found in excellent agreement with available experimental data. A detailed analysis is made for the excitonic structures within the band gap and found that the excitons belong to the Frenkel class and are tightly confined within the layers. The calculated exciton binding energy is much larger than that obtained by Watanabe {\it et al} using a Wannier model to interpret their experimental results and assuming that h-BN is a direct-band-gap semiconductor.Comment: 4 pages, 3 figure

Donde no habite el olvido : Herencia y transmisión del testimonio en Chile

Ya a partir del t\uedtulo mismo, que pretende subrayar el dinamismo impl\uedcito en todo acto testimonial, esta recopilaci\uf3n de ensayos se inserta en el debate contempor\ue1neo sobre la elaboraci\uf3n de la memoria cultural en los escenarios chilenos, debate que sigue generando una serie de contundentes reflexiones sobre los procesos de mediaci\uf3n y traducci\uf3n de la palabra de los sobrevivientes de la dictadura, los usos pol\uedticos y jur\ueddicos de las diferentes \u2018narraciones del yo\u2019, en su transici\uf3n hacia lo p\ufablico, la funci\uf3n del testimonio en los procesos de construcci\uf3n del imaginario de una nueva sociedad, supuestamente democr\ue1tica y progresista. \ubfCu\ue1l es la funci\uf3n del testigo frente a las pol\uedticas del estado? \ubfCu\ue1les son las instancias que definen la producci\uf3n y recepci\uf3n de su palabra? \ubfC\uf3mo visibilizar las huellas del testimonio en una realidad amn\ue9sica, cada vez m\ue1s condicionada por el mercado? Estas cuestiones se cruzan con preocupaciones de orden literario, aptas a reflexionar sobre las definiciones del testimonio como g\ue9nero, la posibilidad de detectar una tipolog\ueda de las m\ufaltiples formas narrativas que lo caracterizan, los elementos est\ue9ticos y ret\uf3ricos que trazan una historia de resistencia y sobrevivencia, la determinaci\uf3n de un imaginario com\ufan

Trunk motion analysis: a systematic review from a clinical and methodological perspective

INTRODUCTION: This systematic literature review aims to check the current state of affairs of non-gait-related optoelectronic trunk movement analysis; results have been analyzed from a clinical and a methodological perspective. EVIDENCE ACQUISITION: Extensive research was performed on all papers published until December 31st, 2015, dealing with trunk movement analysis assessed by optoelectronic systems, excluding those related to gait. The research was performed on the 14th of January 2016 on three databases: Scopus, Science Direct and Pubmed. A reference search and expert consultation were also performed. EVIDENCE SYNTHESIS: Out of a total number of 8431 papers, 45 were deemed relevant: they included 1334 participants, 57.9% healthy, with age range 8-85. Few studies considered the whole trunk, and none focused on each vertebra independently: the trunk was almost always divided into three segments. Thirteen studies included 20 or more markers. Most of the papers focused mainly on the biomechanics of various movements; the lumbar area and low back pain were the most studied region and pathology respectively. CONCLUSIONS: This study has shown the relative scarcity of current literature focusing on trunk motion analysis. In clinical terms, results were sparse. The only quite well represented group of papers focused on the lumbar spine and pathologies, but the scarcity of individuals evaluated make the results questionable. The use of optoelectronic systems in the evaluation of spine movement is a growing research area. Nevertheless, no standard protocols have been developed so far. Future research is needed to define a precise protocol in terms of number and position of markers along the spine and movements and tasks to be evaluated