A Surface Reconstruction with a Fractional Hole: (5×5)R26.6∘(\sqrt{5}\times\sqrt{5}) R26.6^\circ LaAlO3_3 (001)

The structure of the $(\sqrt{5}\times\sqrt{5})R26.6^\circ$ reconstruction of LaAlO$_3$ (001) has been determined using transmission electron diffraction combined with direct methods. The structure is relatively simple, consisting of a lanthanum oxide termination with one lanthanum cation vacancy per surface unit cell. The electronic structure is unusual since a fractional number of holes or atomic occupancies per surface unit cell are required to achieve charge neutrality. Density functional calculations indicate that the charge compensation mechanism occurs by means of highly delocalized holes. The surface contains no oxygen vacancies and with a better than 99% confidence level, the holes are not filled with hydrogen. The reconstruction can be understood in terms of expulsion of the more electropositive cation from the surface followed by an increased covalency between the remaining surface lanthanum atoms and adjacent oxygen atoms.Comment: 4 Pages, 3 Figure

Investigating the effect of child maltreatment on early adolescent peer-on-peer sexual aggression: testing a multiple mediator model in a non-incarcerated sample of Danish adolescents

Objective: The aim of the present study was to investigate the relationship between child maltreatment and severe early adolescent peer-on-peer sexual aggression, using a multiple mediator model. Methods: The study comprised 330 male Grade 9 students with a mean age of 14.9 years (SD=0.5). Results: Estimates from the mediation model indicated significant indirect effects of child physical abuse on sexual aggression via peer influence and insecure-hostile masculinity. No significant total effect of child sexual abuse and child neglect on sexual aggression was found. Conclusions: Findings of the present study identify risk factors that are potentially changeable and therefore of value in informing the design of prevention programs aiming at early adolescent peer-on-peer sexual aggression in at-risk youth

Immersive technology and medical visualisation: a user's guide

The immersive technologies of Virtual and Augmented Reality offer a new medium for visualisation. Where previous technologies allowed us only two-dimensional representations, constrained by a surface or a screen, these new immersive technologies will soon allow us to experience three dimensional environments that can occupy our entire field of view. This is a technological breakthrough for any field that requires visualisation, and in this chapter I explore the implications for medical visualisation in the near-to-medium future. First, I introduce Virtual Reality and Augmented Reality respectively, and identify the essential characteristics, and current state-of-the-art, for each. I will then survey some prominent applications already in-use within the medical field, and suggest potential use cases that remain under-explored. Finally, I will offer practical advice for those seeking to exploit these new tools