We demonstrate an active metamaterial device that allows to electrically control terahertz transmission over more than one order of magnitude. Our device consists of a lithographically defined gold nano antenna array fabricated on a thin film of vanadium dioxide (VO(2)), a material that possesses an insulator to metal transition. The nano antennas let terahertz (THz) radiation funnel through when the VO(2) film is in the insulating state. By applying a dc-bias voltage through our device, the VO(2) becomes metallic. This electrically shorts the antennas and therefore switches off the transmission in two distinct regimes: reversible and irreversible switching.

We report on an order of magnitude enhanced nonlinear response of vanadium dioxide thin film patterned with nanoresonators--nano slot antennas fabricated on the gold film. Transmission of terahertz radiation, little affected by an optical pumping for the case of bulk thin film, can now be completely switched-off: DeltaT/T approximately -0.9999 by the same optical pumping power. This unprecedentedly large optical pump-terahertz probe nonlinearity originates from the insulator-to-metal phase transition drastically reducing the antenna cross sections of the nanoresonators. Our scheme enables nanoscale-thin film technology to be used for all-optical switching of long wavelength light.

The antineoplastic drug paclitaxel is known to block cells in the G2/M phase of the cell cycle through stabilization of microtubules. The development of paclitaxel resistance in tumors is one of the most significant obstacles to successful therapy. Vascular endothelial growth factor (VEGF) and hypoxia-inducible factor 1 (HIF-1) are important regulators of neovascularization. HIF-1 regulates VEGF expression at the transcriptional level. Here, we investigated whether paclitaxel treatment affects VEGF expression for the development of paclitaxel resistance. Paclitaxel treatment induced dose-dependent cell death and increased VEGF expression. Paclitaxel also induced nuclear factor-ĸB activation and stabilized HIF-1α, which stimulated luciferase activity of HIF-1α response element on VEGF gene. As paclitaxel treatment produced reactive oxygen species (ROS), VEGF expression was increased by H₂O₂ treatment and reduced by various ROS scavengers such as N-acetyl-L-cysteine, pyrrolidine dithiocarbamate and diphenylene iodonium. Paclitaxel-induced cell death was aggravated by incubation with those ROS scavengers. Collectively, this suggests that paclitaxel-induced VEGF expression could be mediated by paclitaxel-induced ROS production through nuclear factor-ĸB activation and HIF-1α stabilization, which could affect resistance induction to antitumor therapeutics during cancer treatment.

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Purpose:The purpose of this study was to examine the effects of laughter therapy on mood, state anxiety, and serum cortisol based on a Stress-Coping Model for preoperative breast cancer patients. Methods: The study used a nonequivalent control group pretestposttest design. The participants were 40 breast cancer patients who were admitted to one general hospital for surgery in 2009 (experimental group 23, control group 17). The experimental group received one hour laughter therapy consisting of dance, lots of laughter techniques, and meditation. Results: The mean ages were 47 years (experimental group) and 49 years (control group). There were no significant differences in demographic and disease-related characteristics between the two groups. After the intervention, the scores of mood and state-anxiety of experimental group were significantly improved than those of control group. However, no difference was found in serum cortisol. Conclusion: The laughter therapy was partially effective in improving stress response in patients with breast cancer. Further research is needed to develop and evaluate the longer periods of interventions to testify the effects on serum cortisol, and other biochemical variables.