Metabolic syndrome parameters in adolescents may be determinants for the future periodontal diseases.

AIM: The prevalence of metabolic syndrome (MetS) increases even in adolescents. The evidence that MetS is associated with the periodontal diseases in adolescents has been understudied. Therefore, our aim was to assess the association between MetS parameters and gingivitis in adolescents. MATERIAL AND METHODS: A total of 941 participants (590 boys, 351 girls), aged 12-18 years was selected from the Fourth Korea National Health and Nutrition Examination Survey, a cross-sectional and nationally representative survey, which had had information on waist circumference, blood pressure, serum triglyceride, high-density lipoprotein (HDL) cholesterol, and the fasting blood sugar and community periodontal Index (CPI). RESULTS: The number of positive parameters of MetS showed significant positive correlation with gingivitis; adjusted and crude ORs with one positive parameters of MetS were 1.92 (95% CI: 1.21-3.04) and 1.88(95% CI: 1.28-2.76), respectively. And adjusted OR with three or more positive parameters of MetS was 3.29 (95% CI: 1.24-8.71). Among five parameters of MetS, Low HDL-cholesterol showed significant association with gingivitis (crude OR 2.12, 95% CI 1.20-3.73; adjusted OR 1.96, 95% CI 1.24-3.12). CONCLUSIONS: Having more positive parameters of MetS and low HDL-cholesterol parameter had an independent relationship with the prevalence of gingivitis, which may be determinants for the future periodontal diseases even in adolescents.

Switching of liquid-crystal devices between reflective and transmissive modes using long-pitch cholesteric liquid crystals.

We propose liquid-crystal (LC) devices capable of switching between reflective and transmissive modes using the scattering and transparent states of long-pitch cholesteric LCs (CLCs). Two different device configurations can be realized by changing the location of a CLC layer. Low-power operation without the parallax problem can be achieved using the bistable switching of CLCs. We believe that the proposed devices are potential candidates for highly efficient transflective displays.

Optical configurations for nematic liquid crystal device switchable between reflective and transmissive modes.

We propose an optical configuration for a nematic liquid crystal (LC) device that is switchable between the reflective and the transmissive modes. By placing a reflective polarizer between the two LC layers, we obtain higher reflectance and reduce the parallax effect in the reflective mode. We can eliminate the parallax effect by using a wire-grid polarizer or other in-cell reflective polarizers. We expect that the proposed device can be used in various outdoor applications.

Long-pitch cholesteric liquid crystal cell for switchable achromatic reflection.

We propose a switchable achromatic reflector using a long-pitch cholesteric liquid crystal (CLC) whose Bragg reflection wavelength is chosen to be infrared by controlling the pitch of the CLC so that the planar texture is transparent over the entire visible wavelength. By using the light scattering of the focal conic texture, achromatic reflection can be achieved. Both textures are stable at zero electric field and the operating voltage of the proposed CLC device is much lower than that of conventional CLC devices. The proposed switchable reflector, which can be operated at a low voltage with low power, can be applied to reflective displays and to light shutters. By coupling with a reflective polarizer the efficiency of light scattering at the focal conic texture can be enhanced.

Stereoscopic three-dimensional display based on polarization-switching device with low cross talk and high contrast ratio.

We present a polarization-switching device with dual-frequency liquid crystal material for a stereoscopic three-dimensional (3D) display. This device shows good properties, such as low 3D cross talk and high brightness, due to a fast dynamic response time. Without optical compensation, however, this device has an asymmetric contrast ratio on the left- and right-hand sides of 3D glasses, because the viewing principles on both sides are different from each other. To solve this problem, we design an optical structure with two half-wave plate films using the Jones matrix method. As the results of simulation and experiment show, excellent dark states and high brightness are realized over the entire range of visible wavelengths on both sides.