Specific features of vowel-like signals of white whales

The set of acoustic signals of White-Sea white whales comprises about 70 types of signals. Six of them occur most often and constitute 75% of the total number of signals produced by these animals. According to behavioral reactions, white whales distinguish each other by acoustic signals, which is also typical of other animal species and humans. To investigate this phenomenon, signals perceived as vowel-like sounds of speech, including sounds perceived as a “bleat,” were chosen A sample of 480 signals recorded in June and July, 2000, in the White Sea within a reproductive assemblage of white whales near the Large Solovetskii Island was studied. Signals were recorded on a digital data carrier (a SONY minidisk) in the frequency range of 0.06–20 kHz. The purpose of the study was to reveal the perceptive and acoustic features specific to individual animals. The study was carried out using the methods of structural analysis of vocal speech that are employed in lingual criminalistics to identify a speaking person. It was demonstrated that this approach allows one to group the signals by coincident perceptive and acoustic parameters with assigning individual attributes to single parameters. This provided an opportunity to separate conditionally about 40 different sources of acoustic signals according to the totality of coincidences, which corresponded to the number of white whales observed visually. Thus, the application of this method proves to be very promising for the acoustic identification of white whales and other marine mammals, this possibility being very important for biology.     

Physical processes underlying the development of shear turbulence

A physical model of the development of turbulence in free shear flows is proposed. The model is based on the results of numerical simulations of turbulent flow development. The main ideas of the proposed theory of turbulence are stated as follows: the onset of turbulence begins with the formation of large vortices; spectral energy transfer involves both direct and inverse cascades; and the inertial range of the energy spectrum develops as a result of concurrent direct and inverse cascades. The dominant physical factors that determine the spectrum include Joukowski forces.     

Fermi-liquid effects in transresistivity in quantum Hall double layers near ν=1/2

We present theoretical studies of the temperature and magnetic field dependences of the Coulomb drag transresistivity between two parallel layers of two-dimensional electron gases in the quantum Hall regime near half-filling of the lowest Landau level. It is shown that Fermi-liquid interactions between the relevant quasi-particles can significantly affect the transresistivity, providing its independence of the interlayer spacing for spacings that take values reported in the experiments. The obtained results agree with the experimental evidence.     

Structure of the stochastic layer in a driven pendulum

An analysis of the stochastic layer in a driven pendulum is extended to the case when the separatrix map contains both single-and double-frequency harmonics. Resonance invariants of the first three orders are found for the double-frequency harmonic. Combined with the previously known single-frequency invariants, they can be used to obtain further information about the layer, in particular, to examine the neighborhoods of zeros of Melnikov integrals.     

Theory of periodic states for feedback-controlled photorefractive nonlinear systems

Certain feedback loops can be used in photorefractive optical schemes to implement periodic states and create spatial gratings characterized by extremely high or low diffraction efficiencies. This highly nonlinear phenomenon is studied both experimentally and numerically. An analytical method is developed for analyzing periodic states with the use of symmetries of time-dependent diffraction equations and fast feedback response. The method is applied to describe the properties of periodic states, including their spatial structure, diffraction-efficiency oscillation period and amplitude, and characteristics of feedback-controlled strong phase modulation.     

The contribution of the central region of the electron energy spectrum to the total double photoionization cross section of helium in the asymptotic nonrelativistic energy region

The double photoionization of helium at high photon energies is considered using a nonrelativistic approach. The central region of the energy spectrum and its contribution to the total process cross section and to the ratio between the double and single ionization cross sections are studied. Interelectronic interaction in the initial state is included exactly, whereas the interaction between the fast outgoing electrons is calculated by perturbation theory. A detailed derivation of the expression for the cross section ratio between double and single ionizations is given. The corresponding results obtained by other authors are analyzed and corrected.     

Nontrivial manifestation of clustering in fission of heavy nuclei at low and middle excitations

An analysis of the preferable fission path manifesting itself as a fine structure of the total kinetic energy-mass distribution of the fission fragments compelled us to put forward an absolutely new shape of the fissioning system on the descent from the fission barrier. It is a multicomponent nuclear molecule constituted by two magic clusters and a torus-like neck between.     

Total cross section,inelasticity, and multiplicity distributions in proton-proton collisions

Multiparticle production in high-energy proton-proton collisions has been analyzed in the framework of the strongly correlated quark model of the hadron structure elaborated by the author. It is shown that inelasticity decreases at high energies and the violation of KNO scaling is a consequence of total cross-section growth and increases with collision energy masses of intermediate clusters.     

Dark matter searches by the Boulby Collaboration and liquid xenon prototype development

The current status of direct dark matter searches by the Boulby Dark Matter Collaboration is presented with the latest result from the ZePLiN I liquid xenon detector. An upper limit in the interaction cross section per nucleon of ～1×10^?6 pb for a WIMP mass of 100 GeV is found. Details of ZePLiN’s II and III—two future liquid xenon dark matter are presented. Extensive two-phase liquid-gas xenon prototype work has been undertaken and results of characterization studies are presented. The detector response to internal alpha and external gamma and neutron sources is shown. The potential discrimination power of the two-phase technique is displayed. Finally, prospects for the future dark matter search program are discussed.