Karst landforms can result from a single stage process in which chemical dissolution and mechanical erosion proceed simultaneously or from a two stage process in which chemical dissolution precedes mechanical erosion. During the second of these processes, chemical dissolution leads to the creation of karst features hosting a residual weathering product, here referred to as alterite. An example of one such feature is the enclosed mass of altered rock at Červený Quarry near Klukovice which represents one of the richest localities for exceptionally preserved echinoderm ossicles in the Prague Synform. In this study the processes responsible for the formation of this feature have been investigated. Nineteen samples were obtained from the bioclastic Slivenec Limestone and from these it has been possible to calculate the carbonate volume content, which defines the weathering intensity, and the carbonate rock weathering index, which defines the weathering state. The results demonstrate that carbonate dissolution has not been accompanied by gravitational compaction or the incorporation of mineral inputs. Thin sections analysed under polarised light and under cathodoluminescence emphasise heterogeneous dolomitisation of the limestone. As the weathering grade intensifies, empty rhomboidal pores become increasingly common until, ultimately, the rhomboidal forms are lost due to corrosion and enlargement. In contrast it is rare to find evidence of calcite dissolution and, therefore, the altered mass still hosts almost all of its post dolomitisation micrite, sparite, and bioclasts. Negligible calcite dissolution helps to explain the exceptional nature of the fossil preservation at the site while the dolomite dissolution accounts for the ease with which it is possible to extract the fossils. Further research should focus on better understanding the role of dolomite dissolution in the formation of other important palaeontological localities in the Prague Synform., Matt Rowberry, Caroline Dubois, Olivier Kaufmann, Jean-Marc Baele and Jan Blahůt., and Obsahuje bibliografii
Drawing on a wide range of sources, including informant testimonies, government and diplomatic archives and contemporary published account, the present article seeks to investigate the Ethiopian experience in international food exchange in the first half of the 20th century. Specifically, it sheds light on the primary causes of the internationalization of the country´s food market and the impact this has had on the important question of access to the valued agricultural resources at production sites. Its findings reveal how first the absence and then the slow growth of the food market within the country´s boundaries - most notably in the capital Addis Ababa - contributed to the globalization of the country´s food trade in the half century after its expansion in 1907. The paper demonstrates that the country´s experience in transnational food exchange was unprecedented and its growth and transformation was embedded in politics rather than the economics of supply and demand alone.
A phytosociological synthesis of weed vegetation of southern Moravia (Czech Republic) was performed using the Braun-Blanquet approach. Gradsect sampling, i.e. a priori stratified selection of sampling sites, was used for the field survey. Using this method, 115 quadrants of the Central European mapping grid (6 × 5.6 km) were chosen. Three hundred and ten relevés recorded in 1997–2002 were classified, based on the Cocktail method, which defines sociological species groups and then creates formal definitions of vegetation units. In total, nine associations of the class Stellarietea mediae were distinguished in southern Moravia. Three associations were included in the alliance Caucalidion lappulae (Lathyro-Adonidetum, Euphorbio-Melandrietum, Veronicetum hederifoliotriphylli) and three in the alliance Scleranthion annui (Aphano-Matricarietum, SperguloScleranthetum, Erophilo-Arabidopsietum). For each of the alliances Veronico-Euphorbion, Spergulo-Oxalidion and Panico-Setarion one association was distinguished, respectively, SetarioFumarietum, Panico-Chenopodietum polyspermi and Echinochloo-Setarietum pumilae . Species composition of these associations is documented in a synoptic table. Their structure, ecology, and distribution are commented.
Based on the fuzzy probability distribution and its properties, the paper defines the fuzzy reliability and its characteristics for the double-stage probability model of object. Two fuzzy reliability models are described that are based on the Weibull fuzzy distribution. The results can be applied to determining the reliabililty of real objects in cases where pre-failure times are of a vague numerical type. and Obsahuje seznam literatury
Empirical Mode Decomposition (EMD) is suitable to process the nonlinear and non-stationary time series for filtering noise out to extract the signals. The formal errors are provided along with Global Navigation Satellite System (GNSS) position time series, however, not being considered by the traditional EMD. In this contribution, we proposed a modified approach that called weighted Empirical Mode Decomposition (weighted EMD) to extract signals from GNSS position time series, by constructing the weight factors based on the formal errors. The position time series over the period from 2011 to 2018 of six permanent stations (SCBZ, SCJU, SCMN, HLFY, FJPT, SNXY) were analyzed by weighted EMD, as well as the traditional EMD. The results show that weighted EMD can extract more signals than traditional EMD from original GNSS position time series. Additionally, the fitting errors were reduced 14.52 %, 12.25 % and 8.06 % for North, East and Up components for weighted EMD relative to traditional EMD, respectively. Moreover, 100 simulations of four stations are further carried out to validate the performances of weighted EMD and traditional EMD. The mean Root Mean Squared Errors (RMSEs) are reduced from traditional EMD to weighted EMD with the reductions of 9.08 %, 9.63 % and 6.84 % for East, North and Up components, respectively, which highlights the necessity of considering the formal errors. Therefore, it reasonable to conclude that weighted EMD can extract the signals more than traditional EMD, which can be suggested to analyze GNSS position time series with formal errors., Xiaomeng Qiu, Fengwei Wang, Yunqi Zhou and Shijian Zhou., and Obsahuje bibliografii