W osadach rzeki Raby na południu Polski odkryto pnie czarnych dębów wraz z dobrze zachowanymi chrząszczami o nazwie kozioróg dębosz. Ślady życia tych owadów w kopalnym lub częściowo kopalnym drewnie dostarczają cennych informacji o środowisku i klimacie.

To calculate the transmission coefficient of ultrasonic waves through a multi-layered medium, a new approach is proposed by expanding it into Debye’s series. Using this formalism, the transmission coefficient can be put in the form of resonance terms series. From this point of view, the relative amplitude of the transmitted wave can be considered as an infinite summation of terms taking into account all possible reflections and refractions on each interface. Our model is then used to investigate interaction between the ultrasonic plane wave and the N-plane-layer structure.
Obviously, the resulting infinite summation has to be reduced to a finite one, according to some level of accuracy. The numerical estimation of the transmission coefficient using the exact expression (Eq. (1)) is then compared to the one of our method in the case of two or three plane-layer structure. The effect of the order of the finite summation on the calculated value of the transmission coefficient is, as well, studied. Finally, our proposed method may be used, with the decomposition into Gaussian beams of a pressure field created by a circular source, to draw a 3D image of the pressure field transmitted through a multilayered structure.

Kopię genotypu rośliny macierzystej otrzymujemy, zwykle rozmnażając ją wegetatywnie. Dęby jednak nie rozmnażają się w ten sposób. Co zrobić, żeby zachować wielowiekowe genotypy pomnikowych dębów, które giną?

We build the melting theory and the theory of the Debye temperature for defective and perfect cubic metals mainly based on the statistical moment method. Our theoretical results are applied to metals Ni, Pd and Pt. Our calculations of melting temperatures agree well with experiments and other calculations. Our other calculations are highly reliable.