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Channel gains are frequently used to obtain a secret key that can be used for encryption in physical layer security systems. However, the channel gains captured by the nodes may not always be the same due to channel estimation errors. This would result in a non-zero key error rate (KER). In this letter, we obtain theoretical expressions for KER in orthogonal frequency division multiplexing systems. Tight KER approximations are provided based on Gauss-Laguerre quadrature. A measurementbased study is conducted by using software defined radio nodes to demonstrate the validity and the practicality of the provided results.

Context:Papaver rhoeas L. (Papaveraceae) corn poppy, widely distributed in Turkey, is used to make a cough syrup for children, as a tea for disturbed sleep, for pain relief and as a sedative in folk medicine.Objective: Samples of P. rhoeas collected from eight different locations in Turkey and three from northern Cyprus were investigated for their alkaloid content and screened for their antimicrobial activities.Materials and methods: From the aerial parts of P. rhoeas samples, alkaloids were isolated by column and preparative thin-layer chromatography. The alkaloids were identified by comparing their spectral data (UV, IR and 1H-NMR) and TLC Rf values with those of authentic samples. The antimicrobial study was carried out by microbroth dilution technique against six strains of bacteria and three strains of fungi.Results: Twelve different alkaloids belonging to proaporphine (mecambrine), aporphine (roemerine), promorphinan (salutaridine), protopine (coulteropine and protopine) and rhoeadine (epiglaucamine, glaucamine, glaudine, isorhoeadine, isorhoeagenine, rhoeadine and rhoeagenine) groups were isolated. The most significant activity was observed with the alkaloid extract of P8 against Staphylococcus aureus with a MIC value of 1.22 μg/mL and against Candida albicans with a MIC value of 2.4 μg/mL.Discussion: The results indicate that P. rhoeas samples (P8 and P9), which contain roemerine as their major alkaloid, were the most active extracts.

Abstract-For iterative decoding of multiple antenna systems concatenated with an outer error correcting code, it is important to use an a posteriori probability detector for the MIMO detection to achieve near capacity performance. To avoid full APP detection, we propose a reduced complexity detector based on breadth first algorithms. Although these algorithms are suboptimal, we show that they can provide a good list of candidates for the APP calculation. Furthermore, by exploiting the a priori information delivered from the outer decoder, it is possible to decrease the MIMO detector complexity at each iteration. Using simulation results, we will compare the performance of the proposed detectors with the list sphere detector.

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