Thickness dependence of the properties of epitaxial MgB2 thin films grown by hybrid physical-chemical vapor deposition

We have studied the effect of deposition rate and layer thickness on the properties of epitaxial MgB2 thin films grown by hybrid physical-chemical vapor deposition on 4H-SiC substrates. The MgB2 film deposition rate depends linearly on the concentration of B2H6 in the inlet gas mixture. We found that the superconducting and normal-state properties of the MgB2 films are determined by the film thickness, not by the deposition rate. When the film thickness was increased, the transition temperature, Tc, increased and the residual resistivity, rho0, decreased. Above about 300 nm, a Tc of 41.8 K, a rho0 of 0.28 mikroOhm.cm, and a residual resistance ratio RRR of over 30 were obtained. These values represent the best MgB2 properties reported thus far.Comment: 10 pages, 4 figure

A phase-field model for phase transformations in glass-forming alloys

A phase-field model is proposed for phase transformations in glass-forming alloys. The glass transition is introduced as a structural relaxation, and the competition between the glass and crystalline phases is investigated. The simulations are performed for Cu-Zr alloys, employing thermodynamic and kinetic parameters derived from reported thermodynamic modeling and molecular dynamics simulation results,[1–3] respectively. Four distinct phase fields are treated with a multi-phase-field approach, representing the liquid/glass, Cu10Zr7, CuZr, and CuZr2 phases. In addition, a continuum-field method is applied to the liquid to accommodate the liquid–glass transformation. The combined phase-field approach is used to investigate the glass formation tendency, and critical cooling rates are estimated and compared with the reported experimental values

Social Media, Gender and the Mediatisation of War: Exploring the German Armed Forces’ Visual Representation of the Afghanistan Operation on Facebook

Studies on the mediatisation of war point to attempts of governments to regulate the visual perspective of their involvements in armed conflict – the most notable example being the practice of ‘embedded reporting’ in Iraq and Afghanistan. This paper focuses on a different strategy of visual meaning-making, namely, the publication of images on social media by armed forces themselves. Specifically, we argue that the mediatisation of war literature could profit from an increased engagement with feminist research, both within Critical Security/Critical Military Studies and within Science and Technology Studies that highlight the close connection between masculinity, technology and control. The article examines the German military mission in Afghanistan as represented on the German armed forces’ official Facebook page. Germany constitutes an interesting, and largely neglected, case for the growing literature on the mediatisation of war: its strong antimilitarist political culture makes the representation of war particularly delicate. The paper examines specific representational patterns of Germany’s involvement in Afghanistan and discusses the implications which arise from what is placed inside the frame of visibility and what remains out of its view

AVATAR information extraction system

Abstract The AVATAR Information Extraction System (IES) at the IBM Almaden Research Center enables high-precision, rule-based, information extraction from text-documents. Drawing from our experience we propose the use of probabilistic database techniques as the formal underpinnings of information extrac-tion systems so as to maintain high precision while increasing recall. This involves building a framework where rule-based annotators can be mapped to queries in a database system. We use examplesfrom AVATAR IES to describe the challenges in achieving this goal. Finally, we show that deriving precision estimates in such a database system presents a significant challenge for probabilistic databasesystems

Olap over uncertain and imprecise data

We extend the OLAP data model to represent data ambiguity, specifically imprecision and uncertainty, and introduce an allocation-based approach to the semantics of aggregation queries over such data. We identify three natural query properties and use them to shed light on alternative query semantics. While there is much work on representing and querying ambiguous data, to our knowledge this is the first paper to handle both imprecision and uncertainty in an OLAP setting