Jednym z większych wyzwań, przed jakimi stoi polskie leśnictwo, jest opracowanie nowych strategii hodowli lasów w obliczu postępujących zmian klimatu.

Zanieczyszczenia genetyczne w dobie światowego kryzysu klimatycznego to miecz obosieczny – stwarzają nie tylko nowe możliwości, lecz także ryzyko globalnej katastrofy.

In the era of a global climate crisis, genetic pollution opens up new opportunities, but also carries the risk of a global catastrophe.

Because of the longevity and diversity of trees, dendrological studies often take many years. Research in Kórnik has been underway since 1926.

The knowledge of performance characteristics of turbine stage groups is still insufficient, particularly in the general case of changes of operating conditions. This situation is caused mainly by the scarcity of experimental data available. In such case, the opportunity to obtain the required data, using mathematical modelling and numerical simulation of the operation of stage groups under off-design conditions instead of physical experiment, seems to be attractive. The application of this idea for impulse type turbine stage groups was presented in [I], [2]. Here we discuss similar results but obtained for reaction type turbine stage groups, that is: - mathematical model for computer simulation of operation of reaction type turbine stage group, under variable regime (based on Ainley's and Mathieson's method with some improvements); - simulation results for a number of stage groups designed according to former BBC and traditional concepts; - more general properties of these groups (in relation to flow capacity and efficiency) obtained from the analysis of simulation data; - comparison of observed properties of impulse and reaction typy turbine stage groups.

The paper presents the optimization problem for the multi-element synthetic transmit aperture method (MSTA) in ultrasound imaging applications. The optimal choice of the transmit aperture size is made as a trade-off between the lateral resolution, penetration depth and the frame rate. Results of the analysis obtained by a developed optimization algorithm are presented. The maximum penetration depth and lateral resolution at given depths are chosen as optimization criteria. The results of numerical experiments carried out in MATLAB® using synthetic aperture data of point reflectors obtained by the FIELD II simulation program are presented. The visualization of experimental synthetic aperture data of a tissue mimicking phantom and in vitro measurements of the beef liver performed using the SonixTOUCH Research system are also shown.

Ultrasonic methods of human body internal structures imaging are being continuously enhanced. New algorithms are created to improve certain output parameters. A synthetic aperture method (SA) is an example which allows to display images at higher frame-rate than in case of conventional beam-forming method. Higher computational complexity is a limitation of SA method and it can prevent from obtaining a desired reconstruction time. This problem can be solved by neglecting a part of data. Obviously it implies a decrease of imaging quality, however a proper data reduction technique would minimize the image degradation. A proposed way of data reduction can be used with synthetic transmit aperture method (STA) and it bases on an assumption that a signal obtained from any pair of transducers is the same, no matter which transducer transmits and which receives. According to this postulate, nearly a half of the data can be ignored without image quality decrease. The presented results of simulations and measurements with use of wire and tissue phantom prove that the proposed data reduction technique reduces the amount of data to be processed by half, while maintaining resolution and allowing only a small decrease of SNR and contrast of resulting images.