V tomto příspěvku shrneme současný vývoj v oblasti generace ultrakrátkých pulzů volných elektronů urychlených na vysoké energie, které budou v budoucnu sloužit ke studiu a zobrazování dynamiky elektronických excitací v pevných látkách a nanostrukturách. Za tímto účelem byly vyvinuty dvě optické metody využívající koherentní interakce mezi optickým polem a elektrony ve vakuu., In this contribution we review the recent progress in the field of ultrashort high-energy electron pulse generation for applications in time-resolved imaging of electronic dynamics in bulk solids and nanostructures. For this purpose, two novel experimental techniques have been developed based on the coherent interaction between optical fields and electrons in vacuum., Martin Kozák., and Obsahuje bibliografické odkazy
Attraction of first instar larvae of Spodoptera litura to different colours was studied to determine those that could be used as effective visual attractants for trapping the larvae during dispersal. The larvae were presented with cones of coloured paper. Each cone was placed in the center of a 15-cm Petri dish around the edge of which the larvae were released. Percentage of larvae arriving at the cone was recorded at 5-min intervals over a 15-min period. Differences in the percentages reflected differences in larval attraction to the different colours. The larvae were highly attracted to Foliage Green, Green Bice and Cadmium Yellow. The larvae arrived at the Scarlet Red, Ultramarine Blue, Gray, Orange, White and Black cones in percentages that were almost equal, but lower than at the Foliage Green, Green Bice and Cadmium Yellow cones. Arrival of larvae at the coloured cones increased with time, but their relative preference for different colours remained the same. This study shows that green and yellow can be used as visual attractants in Spodoptera litura larval traps.
Moths are frequently used as indicators of biodiversity or habitat quality. Light traps are the most effective and widely used method for gathering data on moth communities. Knowing the distance from which moths are drawn to a light trap is therefore essential for the ecological interpretation of such data. Two community-wide mark-release-recapture experiments were carried out in forest habitats in central Europe in order to investigate whether the percentage of marked moths recaptured at weak artificial light sources (2 × 15 W UV-light tubes) is dependent on the distance they were released from the light source. Altogether 2,331 moths belonging to 167 species were caught at light traps and released at distances of 2–100 m. Of these moths 313 returned to the light trap within 5 min of release. Percentage recapture was generally low (gross rate 13.4%) and strongly decreased with increase in the distance at which they were released. Percentage recapture was not significantly affected by ambient temperature or the sex of the moths. Only for the Geometroidea was the percentage recaptured slightly greater for the larger species. We found no significant differences between moth super-families with regard to the distance dependence of their attraction to light. Our data confirm that the radius of attraction of low powered light traps for moths is very small often even below 10 m. Thus, moths are good indicators of habitat quality and fragmentation as they are rarely attracted from distant habitats to such light traps., Christine Truxa, Konrad Fiedler., and Obsahuje seznam literatury
One focus of data analysis in formal concept analysis is attribute-significance measure, and another is attribute reduction. From the perspective of information granules, we propose information entropy in formal contexts and conditional information entropy in formal decision contexts, and they are further used to measure attribute significance. Moreover, an approach is presented to measure the consistency of a formal decision context in preparation for calculating reducts. Finally, heuristic ideas are integrated with reduction technique to achieve the task of calculating reducts of an inconsistent data set.