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Stevia (Stevia rebaudiana Bertoni) extract has been recently introduced to Egypt as a non-nutritive sweetener. In this work we tested the possible capability of stevia extract in inducing micro as well as macro DNA lesions. The golden hamster (Mesocricetus auratus; 2n = 44); and human lymphocyte (Homo sapiens, 2n =46) genomes were employed to test the genotoxicity of the extract on a more sensitive genome as well as on the human genome directly. Various short-term genotoxic bioassays were used including analysis of chromosomal abnormalities in hamster bone marrow and human lymphocytes, in vivo induction of sister chromatid exchanges in hamster bone marrow, in vitro induction of sister chromatid exchanges in human lymphocyte culture, micronucleus test in hamster bone marrow.The study shows that the two genomes respond to the extract differently. The extract induces significant levels of chromosome abnormalities in hamster, whereas it does not induce such higher levels of abnormalities in human lymphocyte culture. Analysis of sister chromatid exchange frequencies revealed that the extract induces significant levels of primary DNA damage in hamster bone marrow compared to the human lymphocytes. This study concludes that hamster seems to be more sensitive compared to human and other experimental genetic models used in genotoxic assays. Data from this study and previous studies on other genetic models are discussed.

Radar systems, based on Multistatic radar concept attracted a substantial attention in the recent years. The paper proposes system geometry for S-band Multistatic radar. This technique is used for detecting and tracking the small cross section area and stealthy aircrafts. The proposed geometrical structures are studied with different radars spacing to extend the detection coverage over the Monostatic radar used for air surveillance. The radar detection coverage is also studied with all possible stealthy aircraft paths to find the improvement achieved from using this type of radar. The simulation is done using Matlab program. The results show that the first system geometry with two transmitters and four receivers extends the detection coverage 80 Km for small aircraft and 62 Km for stealthy targets. The second system geometry with two transmitters and six receivers extends the detection coverage 85 Km for small targets and 69 Km for stealthy targets. The achieved SNR from these system geometries guarantee a high probability of detection for small and stealthy aircraft detection.