Serum PCB congener concentrations were measured in 602 adults living near a PCB pollution source in eastern Slovakia. We created iso-concentration maps for 21 PCB congeners by geocoding each participant's place of residence and kriging. Concentrations of PCB congeners were inversely associated with the distance of the participants' residence from the source of pollution. Congener-specific risk factors were derived, particularly for PCBs 52 and 153. We observed that the spatial distribution of serum concentrations was influenced by micro-climatic parameters and physicochemical properties of the congeners. PCB congener profiles strongly correlated with that of the PCB commercial product Delor 106, which was manufactured in the region. The iso-concentration maps indicate that the zones with the highest predicted congener concentration have a mean area of approximately 235.75 ± 188.56 km 2 and the mean enrichment of concentration of congeners in serum in these zones is about 5.12 ± 1.36. We estimate that depending on congener approximately 23 457±18 762 individuals with PCB concentrations exceeding health-based guidance values live in these zones.

The goal of this paper is to provide a mathematical threat modeling methodology and a threat risk assessment tool that may assist security consultants at assessing the security risks in their protected systems/plants, nuclear power plants and stores of hazardous substances: explosive atmospheres and flammable and combustible gases and liquids, and so forth, and at building an appropriate risk mitigation policy. The probability of a penetration into the protected objects is estimated by combining the probability of the penetration by overcoming the security barriers with a vulnerability model. On the basis of the topographical placement of the protected objects, their security features, and the probability of the penetration, we propose a model of risk mitigation and effective decision making.

In paper we analyze the high sensitivity of solutions to nonlinear singularly perturbed second-order dynamical systems on the initial conditions and the value of singular parameter at highest derivative of the mathematical model. Analyzing the potential profile of the system we study the oscillation patterns occurring in the system. The theory is illustrated by numerical simulation.

No abstract

No abstract