Electrostatically Tuned Optical Filters Based on Hybrid Plasmonic-Dielectric Thin Films for Hyperspectral Imaging.

Hyperspectral imaging has a wide range of uses, from medical diagnostics to crop monitoring; however, conventional hyperspectral imaging systems are relatively slow, bulky, and rather costly. In this paper, we present an inexpensive, compact tunable optical filter for hyperspectral applications. The filter is based on a Fabry-Pérot interferometer utilizing hybrid metallic-dielectric mirrors and actuated using a MEMS electrostatic actuator. The optical filter is designed using the transfer matrix method; then, the results were verified by an electromagnetic wave simulator. The actuator is based on a ring-shaped parallel plate capacitor and is designed using COMSOL Multiphysics. An actuation displacement of 170 nm was used, which is the required distance to tune the filter over the whole visible range (400-700 nm). There are two designs proposed for the optical filter: the first was optimized to provide maximum transmission and the other is optimized to have minimum full-width-half-maximum (FWHM) value. The first design has a maximum transmission percentage of 94.45% and a minimum transmission of 86.34%; while the minimum FWHM design had an average FWHM value of 7.267 nm. The results showed improvements over the current commercial filters both in transmission and in bandwidth.

Diagnostic accuracy of posterior cervical angle and cervical length in the prediction of successful induction of labor.

OBJECTIVE: To determine the accuracy of the posterior cervical angle (PCA) compared with the cervical length and the Bishop score in predicting the outcome of induction of labor (IOL). METHODS: The present prospective observational study included IOL candidates who had their PCA and cervical length assessed by transvaginal ultrasonography and the Bishop score at the Obstetrics and Gynecology Department, Kasr El-Aini Hospital, Cairo University, Cairo, Egypt, between April 1 and July 31, 2017. The accuracy of these tests in predicting successful IOL (defined as vaginal delivery) was compared. RESULTS: The analysis included 49 women with successful IOL and 21 women with unsuccessful IOL. The suggested cutoffs for the prediction of successful IOL were a PCA of more than 99.5°, a cervical length of less than 34 mm, and a Bishop score of more than five. The areas under the receiver operating characteristics curves for these three measures were not significantly different. However, a PCA of more than 99.5° had the best sensitivity (91.84%), specificity (90.48), positive predictive value (95.7%), negative predictive value (82.6%), positive likelihood ratio (9.64), and negative likelihood ratio (0.09) compared with the other two predictors. CONCLUSION: A PCA of more than 99.5° yielded the best accuracy in predicting successful IOL compared with the cervical length and the Bishop score. CLINICALTRIALS.GOV: NCT03113227.