The measuring of radon volumetric activity and exhalation rate in ground-level air

The physical and chemical characteristics of radon gas make it a good tracer for use in the application of atmospheric transport models. Radon exhalation rate from soil is one of the most important factors for evaluation of the environmental radon level. For this purpose to find out the volumetric activity of radon in ground-level air the measuring has been made using radon monitor SARAD RTM 2200. Radon volumetric activity and radon exhalation rate in ground-level air and at different depths of soil depending on soil temperature and atmospheric parameters in different seasons of the year was calculated and evaluated in two areas of Vilnius city. It has been established that the volumetric activity of radon and radon exhalation intensity is vertically distributed and the corresponding increase in deeper soil layers, and depends on the specific activity of radium, soil temperature and moisture content, temperature difference between soil and atmospheric temperatures.     

A central limit theorem for quadratic forms in strongly dependent linear variables and its application to asymptotical normality of Whittle's estimate

Summary A central limit theorem for quadratic forms in strongly dependent linear (or moving average) variables is proved, generalizing the results of Avram [1] and Fox and Taqqu [3] for Gaussian variables. The theorem is applied to prove asymptotical normality of Whittle's estimate of the parameter of strongly dependent linear sequences.     

ARCH-type bilinear models with double long memory

We discuss the covariance structure and long-memory properties of stationary solutions of the bilinear equation X_t=ζ_tA_t+B_t,(), where are standard i.i.d. r.v.'s, and A_t,B_t are moving averages in X_s, s<t. Stationary solution of () is obtained as an orthogonal Volterra expansion. In the case A_t≡1, X_t is the classical AR(∞) process, while B_t≡0 gives the LARCH model studied by Giraitis et al. (Ann. Appl. Probab. 10 (2000) 1002). In the general case, X_t may exhibit long memory both in conditional mean and in conditional variance, with arbitrary fractional parameters and , respectively. We also discuss the hyperbolic decay of auto- and/or cross-covariances of X_t and X_t² and the asymptotic distribution of the corresponding partial sums’ processes.     

Two-dimensional electronic spectroscopy reveals ultrafast energy diffusion in chlorosomes

Chlorosomes are light-harvesting antennae that enable exceptionally efficient light energy capture and excitation transfer. They are found in certain photosynthetic bacteria, some of which live in extremely low-light environments. In this work, chlorosomes from the green sulfur bacterium Chlorobaculum tepidum were studied by coherent electronic two-dimensional (2D) spectroscopy. Previously uncharacterized ultrafast energy transfer dynamics were followed, appearing as evolution of the 2D spectral line-shape during the first 200 fs after excitation. Observed initial energy flow through the chlorosome is well explained by effective exciton diffusion on a sub-100 fs time scale, which assures efficiency and robustness of the process. The ultrafast incoherent diffusion-like behavior of the excitons points to a disordered energy landscape in the chlorosome, which leads to a rapid loss of excitonic coherences between its structural subunits. This disorder prevents observation of excitonic coherences in the experimental data and implies that the chlorosome as a whole does not function as a coherent light-harvester.     

Hyperbolic asymptotics in Burgers' turbulence and extremal processes

Large time asymptotics of statistical solutionu(t,x) (1.2) of the Burgers' equation (1.1) is considered, whereξ(x)=ξ _L(x) is a stationary zero mean Gaussian process depending on a large parameterL>0 so that $$\xi _L (x) \sim \sigma _L \eta (x/L)(L \to \infty ),$$ where $\sigma _L = L^2 (2\log L)^{1/2} $ and η(x) is a given standardized stationary Gaussian process. We prove that asL→∞ the hyperbolicly scaled random fieldsu(L ²t, L²x) converge in distribution to a random field with “saw-tooth” trajectories, defined by means of a Poisson process on the plane related to high fluctuations of ξ(x), which corresponds to the zero viscosity solutions. At the physical level of rigor, such asymptotics was considered before by Gurbatov, Malakhov and Saichev (1991).     

Sound reduction in samples of environmentally friendly building materials and their compositions

In order to reduce the negative effect on the environment, environmentally friendly materials are being chosen for the construction of buildings more and more frequently. The building materials that are now used more commonly are clay, straw and reeds. The sound insulation properties of these environmentally friendly materials have not yet been examined thoroughly. This paper presents most commonly used sound reduction indexes R_W that have been measured in the semi-anechoic chamber and determined during the simulation. It has been found that adobe, pressed straw and reeds (oriented parallel to the sound transmission) are suitable for low-frequency sound insulation. The material with the best sound reduction index was adobe. The sound reduction index R_W of a 200 mm thick adobe wall reached up to 43 dB.     

Coupling of solid-phase microextraction continuous bed (monolithic) capillaries with capillary zone electrophoresis for direct analysis of drugs in biological fluids

Hyperlink robust biocompatible solid-phase microextraction (SPME) devices were prepared using continuous bed (monolithic) restricted-access media (RAM) as the SPME capillary insert. The RAM-based SPME approach was able to simultaneously separate proteins from a biological sample, while directly extracting the active components of caffeine, paracetamol and acetylsalicylic acid from the drug NeoCitramonum. The devices were interfaced with a CZE system and fully automated analysis for sample preconcentration, desorption, separation and quantification of analytes was evaluated. Comparative study of in-line coupled SPME-CZE using RAM and RP capillary inserts was carried out. Using an SPME (RAM) insert, the calculated caffeine, paracetamol and acetylsalicylic acid LODs in a bovine plasma sample were 0.3, 0.8 and 1.9 ng/mL, respectively.