The English and Chinese language versions of the Short Form 12-item Health Survey are equivalent

Background: The Short Form 12-item Health Survey (SF-12v2) was originally developed in English, but it is also available in Hong Kong (HK) Chinese. While both language versions had their measurement properties well assessed in their respective populations, their measurement invariance in scores has not been examined. Therefore, we aimed to assess their measurement invariance. Methods: We conducted a cross-sectional study on individuals aged 18 years or older at a university campus. Those who were bilingual in English and Chinese were randomly assigned to self-complete either the standard English or the HK Chinese SF-12v2. Measurement invariance of the two components and eight scales of the SF-12v2 was concluded if the corresponding 90% confidence interval (CI) for the difference between the two language versions entirely fell within the minimal clinically important difference of ±3 units. Multiple-group confirmatory factor analysis (CFA) was also performed. Results: A total of 1013 participants completed the SF-12v2 (496 in English and 517 in HK Chinese), with a mean age of 22 years (Range 18–58), and 626 participants (62%) were female. There were no significant differences in demographics. Only the physical and mental components and the mental health (MH) scale had their 90% CIs (0.21 to 1.61, − 1.00 to 0.98, and − 0.86 to 2.84, respectively) completely fall within the ±3 units. The multiple-group CFA showed partial strict invariance. Conclusions: The English and HK Chinese versions of the SF-12v2 can be used in studies with their two components and MH scores pooled in the analysis

Promoting resilience for HIV prevention in female sex workers in Hong Kong: a randomised controlled trial

Background: Female sex workers are considered a reservoir of HIV and their psychological health has a role to play in HIV infections. In China, commercial sex workers were reported to account for nearly 50% of heterosexual transmission of HIV. Therefore, HIV prevention targeted at mental health could be an innovative strategy in controlling the infection. We aimed to provide an evidence-based resilience-promoting intervention targeting mental health and ultimately safe sexual practices of female sex workers. Methods: This randomised controlled trial was done at three Hong Kong non-governmental organisations, namely Action for REACH OUT, JJJ Association, and the Society of Rehabilitation and Crime Prevention. Participants in this study were women (aged ≥18 years) who had worked as a sex worker in the previous 6 months. We randomly assigned participants to either intervention or usual care (control) according to a predetermined, computer-generated randomisation list. Both group facilitator and partcipants were unmasked to the group allocation, but an independent researcher who was masked to the treatment allocation administered the questionnaires. About half of the participants were permanent residents of Hong Kong whereas the other half were from mainland China. The six-session resilience-promoting intervention was designed to improve the coping skills, self-esteem, and self-efficacy (i.e. the belief of an individuals’ ability to control their actions to achieve desired goal), as measured by Brief-COPE, the Rosenberg Self-esteem Scale, and the Generalised Self- efficacy Scale of female sex workers. Questionnaires were administered by an independent assessor at baseline, post-treatment, and at 3-months follow-up. Participants in the control group received standard service, which included outreach visits, screening for HIV or sexually transmitted infections, and social activities provided by non-governmental organisations. The primary outcome of this study was the resilience scores measured by Connor-Davidson Resilience Scale. We analysed the differences between the two groups using the intention-to-treat analysis. This study was approved by the University of Hong Kong/Hospital Authority Hong Kong West Cluster Internal Review Board (UW 12-220). Verbal informed consent was obtained from all participants. Findings: 127 female sex workers were randomly assigned: 64 joined the control group and 63 joined intervention group. There were significant differences on the score on resilience, self-esteem, and mental health status between groups at post-intervention and 3- month follow-up. We found that condom use in the intervention group at 3-month follow-up was improved compared with the control group. After controlling for marital status and family size, improved resilience scores were associated with intervention group assignment (odds ratio 2∙95 [95% CI 1∙19–7∙35]; p=0∧021) and self-efficacy (1∧13 [1∧03–1∧24]; p=0∧006). Interpretation: Our findings suggest that resilience-promoting intervention programme was effective in improving the mental health status among Chinese female sex workers. This programme is an innovative approach to HIV prevention by promoting both psychological well-being and safe sex for this high-risk population. Funding: Council for the AIDS Trust Fund and General Research Grant, Research Grants Council, HKSAR

Superconducting Vortex with Antiferromagnetic Core

We show that a superconducting vortex in underdoped high T_c superconductors could have an antiferromagnetic core. This type of vortex configuration arises as a topological solution in the recently constructed SO(5) nonlinear sigma model and in Ginzburg-Landau theory with competing antiferromagnetic and superconducting order parameters. Experimental detection of this type of vortex by \mu SR and neutron scattering is proposed.Comment: revised version; 4 pages, LaTeX, 3 encapsulated postscript figures, submitted to Phys. Rev. Let

Translational Symmetry Breaking in the Superconducting State of the Cuprates: Analysis of the Quasiparticle Density of States

Motivated by the recent STM experiments of J.E. Hoffman et.al. and C. Howald et.al., we study the effects of weak translational symmetry breaking on the quasiparticle spectrum of a d-wave superconductor. We develop a general formalism to discuss periodic charge order, as well as quasiparticle scattering off localized defects. We argue that the STM experiments in $Bi_2Sr_2CaCu_2O_{8+\delta}$ cannot be explained using a simple charge density wave order parameter, but are consistent with the presence of a periodic modulation in the electron hopping or pairing amplitude. We review the effects of randomness and pinning of the charge order and compare it to the impurity scattering of quasiparticles. We also discuss implications of weak translational symmetry breaking for ARPES experiments.Comment: 12 pages, 9 figs; (v2) minor corrections to formalism, discussions of dispersion, structure factors and sum rules added; (v3) discussion of space-dependent normalization added. To be published in PR

Physical activity for cancer survivors: meta-analysis of randomised controlled trials

Objective To systematically evaluate the effects of physical activity in adult patients after completion of main treatment related to cancer

Comparison of two surgical techniques for reconstructing posterolateral corner of the knee: a cadaveric study evaluated by navigation system

Purpose: This study aimed to evaluate the immediate effect on knee kinematics by 2 different techniques of posterolateral corner (PLC) reconstruction. Methods: Five intact formalin-preserved cadaveric knees were used in this study. A navigation system was used to measure knee kinematics (posterior translation, varus angulation, and external rotation) after application of a constant force and torque to the tibia. Four different conditions of the knee were evaluated during the biomechanical test: intact knee and PLC-sectioned knee and PLC-reconstructed knee by the doublefemoral tunnel technique and singlefemoral tunnel technique. Results: Sectioning of the PLC structures resulted in significant increases in external rotation at 30° of flexion from 11.2° (SD, 2.6) to 24.6° (SD, 6.2), posterior translation at 30° of flexion from 3.4 mm (SD, 1.5) to 7.4 mm (SD, 3.8), and varus angulation at 0° of flexion from 2.3° (SD, 2.1) to 7.9° (SD, 5.1). Both reconstruction techniques significantly restored the varus stability. The external rotation and posterior translation at 30° of flexion after reconstruction with the doublefemoral tunnel technique were 10.2° (SD, 1.3) and 3.4° (SD, 2.7), respectively, which were significantly better than those of the singlefemoral tunnel technique. Conclusions: Both techniques of reconstruction showed improved stability compared with PLC-sectioned knees. The doublefemoral tunnel technique in PLC reconstruction showed better rotational stability and resistance to posterior translation than the singlefemoral tunnel technique without compromising varus stability. Clinical Relevance: PLC reconstruction by a doublefemoral tunnel technique achieves better rotational control and resistance to posterior translation

The UN in the lab

We consider two alternatives to inaction for governments combating terrorism, which we term Defense and Prevention. Defense consists of investing in resources that reduce the impact of an attack, and generates a negative externality to other governments, making their countries a more attractive objective for terrorists. In contrast, Prevention, which consists of investing in resources that reduce the ability of the terrorist organization to mount an attack, creates a positive externality by reducing the overall threat of terrorism for all. This interaction is captured using a simple 3×3 “Nested Prisoner’s Dilemma” game, with a single Nash equilibrium where both countries choose Defense. Due to the structure of this interaction, countries can benefit from coordination of policy choices, and international institutions (such as the UN) can be utilized to facilitate coordination by implementing agreements to share the burden of Prevention. We introduce an institution that implements a burden-sharing policy for Prevention, and investigate experimentally whether subjects coordinate on a cooperative strategy more frequently under different levels of cost sharing. In all treatments, burden sharing leaves the Prisoner’s Dilemma structure and Nash equilibrium of the game unchanged. We compare three levels of burden sharing to a baseline in a between-subjects design, and find that burden sharing generates a non-linear effect on the choice of the efficient Prevention strategy and overall performance. Only an institution supporting a high level of mandatory burden sharing generates a significant improvement in the use of the Prevention strategy