Polarization dependence of semiconductor exciton and biexciton contributions to phase-resolved optical two-dimensional Fourier-transform spectra

We study the coherent light-matter interactions of GaAs quantum wells associated with excitons, biexcitons and many-body effects. For most polarization configurations, excitonic features dominate the phase-resolved two-dimensional Fourier-transform (2DFT) spectra and have dispersive lineshapes, indicating the presence of many-body interactions. For cross-linear excitation, excitonic features become weak and absorptive due to the strong suppression of many-body effects; a result that can not be directly determined in transient four-wave mixing experiments. The biexcitonic features do not weaken for cross-polarized excitation and thus are more important.Comment: 4 page, 3 figures, journal article - rapid communicatio

GrassPlot v. 2.00 – first update on the database of multi-scale plant diversity in Palaearctic grasslands

Abstract: GrassPlot is a collaborative vegetation-plot database organised by the Eurasian Dry Grassland Group (EDGG) and listed in the Global Index of Vegetation-Plot Databases (GIVD ID EU-00-003). Following a previous Long Database Report (Dengler et al. 2018, Phyto- coenologia 48, 331–347), we provide here the first update on content and functionality of GrassPlot. The current version (GrassPlot v. 2.00) contains a total of 190,673 plots of different grain sizes across 28,171 independent plots, with 4,654 nested-plot series including at least four grain sizes. The database has improved its content as well as its functionality, including addition and harmonization of header data (land use, information on nestedness, structure and ecology) and preparation of species composition data. Currently, GrassPlot data are intensively used for broad-scale analyses of different aspects of alpha and beta diversity in grassland ecosystems

2007. Patterns of epixylic vegetation on spruce logs in late-successional boreal forests. Forest Ecology and Management

Abstract There is a wide diversity in composition and structure of epixylic vegetation that depends on the stage of overgrowing, species of logs, ecological conditions, geographical position and random factors. We analyzed vegetation on spruce logs in the late successional spruce forests of the Sphagnum-Myrtillus, Myrtillus and Oxalis types in northwestern Russia. Vascular plants, lichens, hepatics and mosses constitute, respectively, 18, 17, 21 and 44% of the flora on the decaying wood. The total number of species increases from the first to the second stage of overgrowing, and then decreases at the fourth stage. However, the number of species per plot barely changes. The dynamics of epixylic species and generalists depend on the phytosociological conditions. The described sequences of vegetation are divided into three types of microsuccession. The first type is characterized by the dominance of the epiphytes in the early stages and the epigeous species in the late stages. The low abundance of generalists and epixylics is observed in the spruce forests with well-developed ground feather moss cover. The second type of microsuccession has a small coverage and number of epigeous species and a significant share of generalists on the latter stages of overgrowing. It is connected with the herb-rich, mainly deciduous forests. The third type of microsuccession includes one more stage where one group of ground flora mosses (green mosses) is replaced with another one (Sphagnum). This is characteristic for the Sphagnum-Myrtillus type of spruce forests.

Fieldpractice in Higher Education System. Resume of IV International Conference in the Crimea

Brief information on the IV International Conference Field Practice in the Higher Education System held in the Crimea. Field practice is a part of educational program when students go to other regions in summer to apply on-site the competences and skills they obtained. Field practice is widely used in training of geologists, biologists, geophysicists, historians etc