Extreme precipitation events in the Czech Republic in the context of climate change

As an introduction, short survey of two analyses of long-term fluctuations of annual precipitation totals in the Czech Republic is presented. The main focus of this paper is to contribute to investigation of precipitation trends in the Czech Republic by another point of view. For every pixel of 1 km<sup>2</sup> size, annual maxima of daily precipitation were obtained for time period of 112 years (1895–2006). Based on these time series, we were trying to answer question if there are some changes of area size/distribution of annual maximum of daily precipitation totals. Courses and trends are analyzed for some parameters of area distribution of annual maximum of daily precipitation totals in the area of the Czech Republic. No significant climate changes of tested precipitation characteristics were found

Complex method for angular-spectral analysis of volume phase diffraction gratings recorded in photopolymers

Photopolymer recording materials are nowadays widely used for recording of diffraction gratings and other diffraction elements. For obtaining the best performance of these diffraction gratings for desired applications, it is important to assess these gratings from many different perspectives. In this contribution, we present an experimental and characterization approach to an analysis of diffraction gratings recorded into photopolymer materials. This approach is able to provide a complex and very illustrative description of these gratings response and, with accordance to the theory, information about some important grating parameters, such as a spatial period, slant angle, etc., as well. This approach is based on the measurement of a grating response for a wide range of angles and wavelengths and then on the construction and subsequent analysis of maps in the angular-spectral plane. It is shown that the measurements are in a good agreement with the theoretical predictions based on either approximate (Kogelnik’s coupled wave theory) or rigorous (RCWA) techniques and that this approach provides complex and detailed characterization of the grating response which can be used for additional optimization or decision of applicability of measured sample gratings

Electron Acceleration by Relativistic Surface Plasmons in Laser-Grating Interaction

The generation of energetic electron bunches by the interaction of a short, ultraintense (I>1019 W/cm2) laser pulse with "grating" targets has been investigated in a regime of ultrahigh pulse-to-prepulse contrast (1012). For incidence angles close to the resonant condition for surface plasmon excitation, a strong electron emission was observed within a narrow cone along the target surface, with energy spectra peaking at 5-8 MeV and total charge of ∼100 pC. Both the energy and the number of emitted electrons were strongly enhanced with respect to simple flat targets. The experimental data are closely reproduced by three-dimensional particle-in-cell simulations, which provide evidence for the generation of relativistic surface plasmons and for their role in driving the acceleration process. Besides the possible applications of the scheme as a compact, ultrashort source of MeV electrons, these results are a step forward in the development of high-field plasmonics

Session 10 Photosynthesis

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