Defects and boundary layers in non-Euclidean plates

We investigate the behavior of non-Euclidean plates with constant negative Gaussian curvature using the F\"oppl-von K\'arm\'an reduced theory of elasticity. Motivated by recent experimental results, we focus on annuli with a periodic profile. We prove rigorous upper and lower bounds for the elastic energy that scales like the thickness squared. In particular we show that are only two types of global minimizers -- deformations that remain flat and saddle shaped deformations with isolated regions of stretching near the edge of the annulus. We also show that there exist local minimizers with a periodic profile that have additional boundary layers near their lines of inflection. These additional boundary layers are a new phenomenon in thin elastic sheets and are necessary to regularize jump discontinuities in the azimuthal curvature across lines of inflection. We rigorously derive scaling laws for the width of these boundary layers as a function of the thickness of the sheet

Embedding initial data for black hole collisions

We discuss isometric embedding diagrams for the visualization of initial data for the problem of the head-on collision of two black holes. The problem of constructing the embedding diagrams is explicitly presented for the best studied initial data, the Misner geometry. We present a partial solution of the embedding diagrams and discuss issues related to completing the solution.Comment: (27pp text, 11 figures

Theory of differential inclusions and its application in mechanics

The following chapter deals with systems of differential equations with discontinuous right-hand sides. The key question is how to define the solutions of such systems. The most adequate approach is to treat discontinuous systems as systems with multivalued right-hand sides (differential inclusions). In this work three well-known definitions of solution of discontinuous system are considered. We will demonstrate the difference between these definitions and their application to different mechanical problems. Mathematical models of drilling systems with discontinuous friction torque characteristics are considered. Here, opposite to classical Coulomb symmetric friction law, the friction torque characteristic is asymmetrical. Problem of sudden load change is studied. Analytical methods of investigation of systems with such asymmetrical friction based on the use of Lyapunov functions are demonstrated. The Watt governor and Chua system are considered to show different aspects of computer modeling of discontinuous systems

Roles of age, gender and psychological difficulties in adolescent mentalizing

INTRODUCTION: Adolescence is a critical period for the development of mentalizing – the imaginative capacity to understand one's own and others' behaviour in terms of underlying mental states. Yet, factors and mechanisms underlying individual differences in adolescent mentalizing remain poorly understood. This exploratory study examined whether and how a) age and gender and b) psychological difficulties correlate with mentalizing performance in adolescents from the general population. METHODS: 89 adolescents from Geneva, Switzerland (54 females, age 12–17 years) completed a computerized task of mentalizing and a self-report measure of psychopathology. RESULTS: Mentalizing performance improved with age. Males showed lower scores on the mentalizing task and made more hypermentalizing errors than females. The main findings revealed a negative association between mentalizing performance and self-reported attention problems. Post-hoc analyses further demonstrated that self-reported attentional difficulties were particularly associated with weaker scores on items requiring mentalizing about intentions, while self-reported withdrawal/depression symptoms were particularly associated with weaker scores on items requiring mentalizing about emotions and thoughts. CONCLUSION: The present study highlights a negative association between attentional difficulties and mentalizing performance in community adolescents. Moreover, it provides preliminary evidence suggesting that age, gender and psychological difficulties can be distinctively associated with patterns of correct and incorrect mentalizing in community adolescents. Implications for future research and clinical practice are discussed

Including gaming disorder in the ICD-11: the need to do so from a clinical and public health perspective

The proposed introduction of gaming disorder (GD) in the 11th revision of the International Classification of Diseases (ICD-11) developed by the World Health Organization (WHO) has led to a lively debate over the past year. Besides the broad support for the decision in the academic press, a recent publication by van Rooij et al. (2018) repeated the criticism raised against the inclusion of GD in ICD-11 by Aarseth et al. (2017). We argue that this group of researchers fails to recognize the clinical and public health considerations, which support the WHO perspective. It is important to recognize a range of biases that may influence this debate; in particular, the gaming industry may wish to diminish its responsibility by claiming that GD is not a public health problem, a position which maybe supported by arguments from scholars based in media psychology, computer games research, communication science, and related disciplines. However, just as with any other disease or disorder in the ICD-11, the decision whether or not to include GD is based on clinical evidence and public health needs. Therefore, we reiterate our conclusion that including GD reflects the essence of the ICD and will facilitate treatment and prevention for those who need it

Transmittance optical characteristics of columnar nanoscale niobia arrays formed via anodizing of Al/Nb layers on glass

Anisotropic columnar nanoscale niobia arrays formed via anodizing Al/Nb bilayers on glass showed the sensitivity of transmittance characteristics to the light polarization, which can serve as a basis for applications in photonics and integrated optics

Anodic aluminum oxide formed in aqueous solutions of chelated complex zinc and cobalt compounds

The galvanostatic anodizing results of specially prepared high-purity aluminum in aqueous solutions of complex compounds K3[Co(C2O4)3] and K2[Zn(edta)] of various concentrations in the current density ranges 1.5−1.10 · 102 and 1.5−30 mA · cm−2, respectively. The kinetic features of anodizing have been established, indicating the occurrence of an oscillatory electrochemical process. Morphological features of a flaky and loose nature for K2[Zn(edta)] and monolithic for K3[Co(C2O4)3], uncharacteristic for anodic aluminum oxide, were revealed. The elemental composition, IR spectroscopic and photoluminescent characteristics of the formed oxides are shown

Prioritising action on alcohol for health and development

Despite the existence of cost effective interventions to reduce harmful use of alcohol, many countries are not giving it the attention it deserves, say Dag Rekve and colleaguesfals