Ion abundances of low-energy quiet period particle fluxes at 1 AU

The ion abundances of charged particle fluxes with energies of 0.032–1.28 MeV/nucleon during the quiet period of solar activity are investigated using spacecraft data. The values of Fe/O ratios obtained in 35 such periods in the 23rd solar cycle are compared with the mean ion abundances in the solar corona, in the gradual and impulsive solar energetic particle events, and in the solar wind. It is believed that coronal holes near the equator could be one of possible source of background low energy particle fluxes.     

Measurement of the <Superscript>222</Superscript>Rn background in the DEVIS experiment

In the DEVIS tracking experiment that is being performed at the Institute of Theoretical and Experimental Physics (ITEP, Moscow, Russia) and which is devoted to searches for ¹³⁶Xe double-beta decay, the ²²²Rn concentration is measured in xenon samples with different content of the isotope ¹³⁶Xe. The number of probable double-electron events from ²¹⁴Bi decay mimicking the double-beta decay of ¹³⁶Xe is estimated.     

Polarization-universal bandgap in periodically twisted nematics

Cholesteric liquid crystals are known to possess bandgap and exhibit strong reflection for one of two circular polarizations of light. We suggest a periodically twisted nematic liquid crystal as a medium, which possesses bandgap and exhibits strong reflection for any polarization of normally incident light. Two possible structures are considered: a sinusoidal modulation profile and a rectangular modulation profile. In both cases, the maximum bandgap of a periodically twisted structure is approximately twice as narrow as that of cholesterics. However, the polarization properties of these structures may make them more advantageous than cholesterics in a variety of applications.     

Statistically enhanced self-attraction of random patterns

In this work we develop a theory of interaction of randomly patterned surfaces as a generic prototype model of protein-protein interactions. The theory predicts that pairs of randomly superimposed identical (homodimeric) random patterns have always twice as large magnitude of the energy fluctuations with respect to their mutual orientation, as compared with pairs of different (heterodimeric) random patterns. The amplitude of the energy fluctuations is proportional to the square of the average pattern density, to the square of the amplitude of the potential and its characteristic length, and scales linearly with the area of surfaces. The greater dispersion of interaction energies in the ensemble of homodimers implies that strongly attractive complexes of random surfaces are much more likely to be homodimers, rather than heterodimers. Our findings suggest a plausible physical reason for the anomalously high fraction of homodimers observed in real protein interaction networks.     

On the electromagnetic detection of gravitational waves

The general principles of the electromagnetic detection of gravitational waves are discussed. A critical comment on a previous paper by Baierlein [1] devoted to the same problem is given.     

Elastic backward scattering of negative pions on protons at 25 and 38 GeV/c

The backward elastic scattering reaction π^?p → pπ^? at momenta 25 and 38 GeV/c have been measured using a magnetic spectrometer with hybrid chambers. The experimental data on the dependence of the cross section dσ/du on the momentum transfer u as well as the energy dependence dσ/du at u = 0 are given.     

High-efficiency 1.5 microm thick optical axis grating and its use for laser beam combining

We demonstrate an optical axis grating (OAG) recorded in a nematic liquid crystal that yields a higher than 80% diffraction efficiency and over 800:1 switching contrast between diffraction orders for a laser beam of a red wavelength in a material layer only 1.5 microm thick. The grating was used for combining two laser beams with high efficiency. These observations prove the feasibility of new generation high-efficiency diffractive optical components, which are most promising for infrared and high-power applications owing to their enhanced transparency and reduced thermal effects in thin material layers.     

Motor proteins transporting cargos

Processive motor proteins such as kinesin and myosin-V are enzymes that use the energy of ATP hydrolysis to travel along polar cytoskeletal filaments. One of the functions of these proteins is the transport of vesicles and protein complexes that are linked to the light chains of the motors. Modeling the light chain by a linear elastic spring, and using the two-state model for one- and two-headed molecular motors, we study the influence of thermal fluctuations of the cargo on the motion of the motor-cargo complex. We solve numerically the Fokker-Planck equations of motor motion, and find that the mean velocity of the motor-cargo complex decreases monotonously as the spring becomes softer. This effect is due to the random force of thermal fluctuations of the cargo disrupting the operation of the motor. Increasing the size (thus, the friction coefficient) of the cargo also decreases the velocity. Surprisingly, we find that for a given size of the cargo, the velocity has a maximum for a certain friction of the motor. We explain this effect by the interplay between the characteristic length of thermal fluctuations of the cargo on a spring, the motor diffusion length, and the filament period. Our results may be relevant for the interpretation of single-molecule experiments with molecular motors (bead assays), where the motor motion is observed by tracking of a bead attached to the motor.     

Thermomechanical coupling in a cylindrical hybrid-aligned nematic liquid crystal

A solution to the system of equations describing a cylindrical hybrid-aligned nematic liquid crystal is obtained. The rotational flow driven by vertical temperature gradient in such a cell is investigated theoretically. The cell is suggested as a new experimental setup for determining an additional relation required to measure the twelve thermomechanical coefficients. It is shown that the terms in the expressions for thermomechanical stress and heat flux obtained in [8] are equivalent to those originally proposed in [7].     

Paradoxes of unstable electron

The hypothesis that an electron is unstable — when we try to make it consistent with the vanishing mass of the photon-leads to a number of paradoxical statements. The lifetime of the electron is determined by emission of a huge number of longitudinal photons and depends exponentially on the amount of emitted energy. This suggests to discuss searches for charge nonconservation in experiments with high energy particles.