A phytosociological synthesis of the segetal vegetation in the Czech Republic was performed using methods of the Zürich-Montpellier school. In total, 712 relevés made by the author in this country in 1955–2000 were classified, and 22 associations and one unranked community were distinguished. Each syntaxon is characterized by diagnostic species, documented by a synoptic table, and the syntaxonomy, structure, species composition, ecology, dynamics, distribution and variability of each syntaxon are commented on. Names are revised according to the rules of the International Code of Phytosociological Nomenclature. All syntaxa belong to the class Stellarietea mediae and associations are assigned to the orders Centaureetalia cyani (alliances Caucalidion lappulae, Fumario-Euphorbion, and Sherardion), Atriplici-Chenopodietalia (alliances Scleranthion annui, Polygono-Chenopodion polyspermi, Arnoseridion minimae, and Panico-Setarion), and Eragrostietalia (alliance Eragrostion).
The article focuses on the application of the segmentation algorithm based on the numerical solution of the Allen-Cahn non-linear diffusion partial differential equation. This equation is related to the motion of curves by mean curvature. It exhibits several suitable mathematical properties including stable solution profile. This allows the user to follow accurately the position of the segmentation curve by bringing it quickly to the vicinity of the segmented object and by approaching the details of the segmentation curve. The purpose of the article is to indicate how the algorithm parameters are set up and to show how the algorithm behaves when applied to the particular class of medical data. In detail we describe the algorithm parameters influencing the segmentation procedure. The left ventricle volume estimated by the segmentation of scanned slices is evaluated through the cardiac cycle. Consequently, the ejection fraction is evaluated. The described approach allows the user to process cardiac cine MR images in an automated way and represents, therefore, an alternative to other commonly used methods. Based on the physical and mathematical background, the presented algorithm exhibits the stable behavior in the segmentation of MRI test data, it is computationally efficient and allows the user to perform various implementation improvements.
The motion of GPS permanent stations during three earthquakes has been investigated with the use of Precise Point Positioning (PPP) technique and the seismological data. The study examines the ability of high-rate GPS observations to reflect the ground motion retrieved by the strong motion instruments (SM), considered to be more reliable and precise. The goal of this article is to show the sensitivity of GPS PPP kinematic high-rate positioning with position domain filtering using the band-pass Butterworth filter on small samples of position time series. The kinematic PPP approach in RTKLib software was used, supported by the CODE precise orbit and clock products to estimate positions from 5-hour long GPS phase datasets. Obtained position time series were reduced to 5-minute samples covering the time of co-seismic motion. The application of Butterworth band-pass filtering of GPS and seismological time series increased the agreement between them up to 72 % in terms of correlation, resulting in correlations within the range 0.34 to 0.99. The comparison of peak ground displacements (PGD) revealed that for Italian events, GPS–SM absolute value of the average difference is 6 mm with GPS–SM distances within the range of 0.05 to 2.14 km. In all analysed earthquakes, the agreement between GPSgrams and seismograms in terms of the first P-arrival polarity was checked and it was found that it is consistent in all cases. This confirms the GNSS technique capability for determining fault plane solution for earthquakes with magnitudes over 6.
Secondary labour markets usually involve job positions with forced flexibility and non-standard working conditions (part-time contracts, fixed-term contracts, work without a contract). They are characterized by no advancement prospects or opportunities for further education, exhausting physical work with inadequate wages and job insecurity, and a frequently long and tiring commute. The working conditions in this sector of the labour market often contribute to marginalization and then to the social exclusion of those who happen to be caught long term in this sector of the labour market instead of preventing and saving them from the risk of marginalization and social exclusion. One of the ways in which secondarization occurs is the universal introduction of part-time contracts in a particular sector of the labour market which then becomes an involuntary trap of underemployment, underpaid wage, insecurity and discrimination. The profession of cashier in foreigner retail chains is an example of such a development. This qualitative study shows the step by step degradation of the employment conditions in this sector and how the lives of women and men working in the sector have deteriorated. At the same time, the condition and status of the profession overall are declining. This phenomenon is referred to as the "secondarization" process, Marcel Tomášek, Radka Dudová., and Obsahuje bibliografii