The article presents methods that help in the elimination of mutual clutter as well as the consequences of two FM sounding signal sonars operating in the same body of water and frequency band. An in-depth analysis of mutual clutter was carried out. The effects of sounding signal differentiation were determined, as was the Doppler effect on mutual clutter suppression. One of the methods analysed is of particular interest in a situation in which collaborating sonars are operating in opposite frequency modulation directions. This method is effective for both linear and hyperbolic frequency modulations. A formula was derived, identifying exactly how much quantities of clutter may be lessened. The work included comprehensive computer simulations and measurements as well as tests in real-life conditions.
Polychlorinated biphenyls (PCBs), dichlorodiphenyltrichloroethane (DDT) and its metabolite, dichlorodiphenyldichloroethylene (DDE) can disturb the secretory function of the ovary and both contractions and secretory function of the uterus during the estrus cycle and pregnancy. Additionally, PCBs can pass through the placental barrier into allantoic and amniotic fluid. The presence of PCBs in these fluids is associated with higher frequency of spontaneous abortions and premature births in humans and animals. Therefore, the effect of PCBs, DDT and DDE on the connexins (Cx26, Cx32 and Cx43) and keratin 8 (KRT8) expression in bovine placentomes was investigated. The placentome slices from the second trimester of pregnancy were incubated with PCB153, 126, 77, DDT and DDE (each at doses of 1, 10 or 100 ng/ml) for 48 h. Then, the slices were stained using immunohistochemistry. The density of Cxs staining was measured with Axio- Vision Rel. 4.8 software in fetal-maternal connections and binuclear cells (BNC). None of the tested xenobiotics (XBs) affected the localization of Cxs and KRT8 in the fetal-maternal connection area, but the XBs affected the density of Cxs in fetal-maternal connections and binuclear cells (BNCs). Depend on the doses, in fetal-maternal connections all used PCBs changed the protein expression of different Cxs, while in BNCs, all tested XBs except DDT increased the expression of Cxs. None of investigated XBs affected on KRT8 expression. In summary, used XBs affect the expression of Cxs and change the quantitative relationships between them. Therefore, XBs can unfavorably influence function of the utero-placental barrier in cows.