Topological Anderson Insulator

Disorder plays an important role in two dimensions, and is responsible for striking phenomena such as metal insulator transition and the integral and fractional quantum Hall effects. In this paper, we investigate the role of disorder in the context of the recently discovered topological insulator, which possesses a pair of helical edge states with opposing spins moving in opposite directions and exhibits the phenomenon of quantum spin Hall effect. We predict an unexpected and nontrivial quantum phase termed "topological Anderson insulator," which is obtained by introducing impurities in a two-dimensional metal; here disorder not only causes metal insulator transition, as anticipated, but is fundamentally responsible for creating extended edge states. We determine the phase diagram of the topological Anderson insulator and outline its experimental consequences.Comment: 4 pages, 4 figure

Absence of ferromagnetism in V-implanted ZnO single crystals

The structural and magnetic properties of V doped ZnO are presented. V ions were introduced into hydrothermal ZnO single crystals by ion implantation with fluences of 1.2*10^16 to 6*10^16 cm^-2. Post-implantation annealing was performed in high vacuum from 823 K to 1023 K. The ZnO host material still partly remains in a crystalline state after irradiation, and is partly recovered by annealing. The V ions show a thermal mobility as revealed by depth profile Auger electron spectroscopy. Synchrotron radiation x-ray diffraction revealed no secondary phase formation which indicates the substitution of V onto Zn site. However in all samples no pronounced ferromagnetism was observed down to 5 K by a superconducting quantum interference device magnetometer.Comment: 13 pages, 4 figs, MMM conference 2007, accepted by J. Appl. Phy

Mental Health Experiences of Sex Trafficking Victims in Western Countries: A Qualitative Study

In recent years, human trafficking has received increasing public awareness and media attention, and sex trafficking in particular has become a prevailing human rights issue on a global scale. Despite growing scientific literature in the field, there remains a limited number of international qualitative studies investigating victims’ needs. This study aims to explore the experiences of people who have been sex trafficked in a Western country and how this impacted their mental health, as described in online first-person accounts. First-person online narratives of sex trafficking victims (n = 30) were retrieved from a systematic online search. A thematic analysis identified overarching themes, with the most prominent being 1) preexisting vulnerabilities, 2) psychological mechanisms involved in trafficking (i.e. deception, manipulation), and 3) barriers to recovery. The results showed how preexisting vulnerabilities can impact victims’ susceptibility to trafficking and how psychological control tactics utilized in the trafficking process maintain victims’ vulnerability. The results of this thematic analysis provide insight into the diverse set of mental, social, and legal needs that trafficking victims face and may inform potential post-trafficking interventions to meet these needs and prevention efforts to reduce vulnerability to trafficking. Further implications and methodological considerations are discussed in full

Identification of the dominant diffusing species in silicide formation

Implanted noble gas atoms of Xe have been used as diffusion markers in the growth study of three silicides: Ni2Si, VSi2, and TiSi2. Backscattering of MeV He has been used to determine the displacement of the markers. We found that while Si atoms predominate the diffusion in VSi2 and TiSi2, Ni atoms are the faster moving species in Ni2Si

Effect of Hydrostatic Pressure on the Superconductivity in NaxCoO2.yH2O

The effect of hydrostatic pressure on the superconducting transition temperature of Na{0.35}CoO{2}.yH{2}O was investigated by ac susceptibility measurements up to 1.6 GPa. The pressure coefficient of T{c} is negative and the dependence T{c}(p) is nonlinear over the pressure range investigated. The magnitude of the average dlnT{c}/dp=-0.07 GPa^{-1} is comparable to the pressure coefficient of electron-doped high-T{c} copper oxide superconductors with a similar value of T{c}. Our results provide support to the assumption of two-dimensional superconductivity in Na{0.35}CoO{2}.yH{2}O, which is similar to the cuprate systems, and suggest that intercalation of larger molecules may lead to an enhancement of T{c}.Comment: Revised Manuscrip

The first operation and results of the Chung-Li VHF radar

The Chung-Li Very High Frequency (VHF) radar is used in the dual-mode operations, applying Doppler beam-swinging as well as the spaced-antenna-drift method. The design of the VHF radar is examined. Results of performance tests are discussed