Formation of composite polymeric coatings on pure iron

We have demonstrated possibility of electrochemical preparation of metal-polymer nanocomposites on pure iron and steel electrodes in the course of electrochemically initiated polymerization of 1-vinyl-1,2,4-triazole accompanied with cathode formation of metals. Silver nanoparticles have been uniformly distributed in the formed polymer matrix. The prepared composites possess excellent thermal stability.     

From Dinuclear Systems to Close Binary Stars and Galaxies

The evolution of close binary cosmic objects in the mass-asymmetry coordinate is considered. Conditions for the formation of stable symmetric binary stars and galaxies are analyzed. The role of symmetrization of an asymmetric binary system in the transformation of the potential energy into the internal energy and in the release of a large amount of energy is explained.     

Longitudinal waves propagation in plates in the presence of transversal magnetic field

The problem on longitudinal wave propagation in a plate in the presence of a constant transversal magnetic field is studied. The asymptotic behavior of tangential displacement of the points of the plate median surface is found. It is established that the wave of a given initial shape finally turns into a quasiharmonic one. Published in Matematychni Metody ta Fizyko-Mekhanichni Polya, Vol. 51, No. 1, pp. 194–196, January–March, 2008.     

High-contrast atomic dark resonances formed in a ladder system of rubidium atoms in submicron structures

It is shown that high-contrast resonance of electromagnetically induced transparency (EIT) in a ladder Ξ-system of 5S _1/2-5P _3/2-5D _5/2 levels can be formed in optical cells containing a column of rubidium vapor with thickness L in an interval of 100 nm ≤ L ≤ 780 nm. Using bichromatic laser radiation with certain parameters, an 83% contrast of the EIT resonance (or dark resonance, DR) has been achieved for a vapor column thickness of L = 780 nm. An important condition for the formation of high-contrast DR is that the frequency of the coupling laser radiation must be resonant with the frequency of the corresponding 5P _3/2-5D _5/2 transition (for the probe radiation frequency scanned over the 5S _1/2-5P _3/2 transition). It is also shown that a DR can be formed at a record small vapor column thickness of L ≈ 100 nm. Expressions that can be used to estimate the expected DR width at small L values are presented.     

Quantum non-Markovian Langevin equations and transport coefficients for an inverted oscillator

Based on the non-Markovian quantum Langevin equations, we obtain time-dependent transport coefficients for an inverted oscillator coupled linearly in the coordinate to a thermostat. We comparatively analyze the diffusion coefficients for harmonic and inverted oscillators and study the role of quantum statistical effects in the passage through a parabolic barrier. __________ Translated from Teoreticheskaya i Matematicheskaya Fizika, Vol. 156, No. 3, pp. 425–443, September, 2008.     

On HOD-supercompactness

During his Fall 2005 set theory seminar, Woodin asked whether V-supercompactness implies HOD-supercompactness. We show, as he predicted, that that the answer is no.     

High contrast <Emphasis Type="Italic">D</Emphasis><Subscript>1</Subscript> line electromagnetically induced transparency in nanometric-thin rubidium vapor cell

The electromagnetically induced transparency (EIT) on the atomic D ₁ line of rubidium is studied using a nanometric-thin cell with atomic vapor column length in the range of L=400–800 nm. It is shown that the reduction of the cell thickness by four orders as compared with an ordinary cm-size cell still allows to form an EIT resonance for L=λ=794 nm with the contrast of up to 40%. Further reduction of thickness to L=λ/2 leads to significant reduction of EIT contrast, verifying that the key parameter for EIT in wavelength-scale-thickness cells is not the value of L itself but L/λ ratio. Remarkable distinctions of EIT formation in nanometric-thin and ordinary cells are demonstrated. Well-resolved splitting of the EIT resonance in a magnetic field for L=λ can be used for magnetometry with nanometric spatial resolution. The presented theoretical model well describes the observed results.     

Bridgman growth and site occupation in LuAG:Ce scintillator crystals

LuAG:Ce single crystals with various activator concentrations were grown by the vertical Bridgman technique. Characterization of crystals was done in terms of actual doping level, macroscopic defects and degree of non-equivalent substitutions by Lu for Al in octahedral lattice sites. Scintillation measurements were performed using 2×2×8 mm³ shaped samples with Ce concentration in the range 0.05–0.55 at%. Essential improvement of performance was demonstrated in samples containing ≥0.2 at% of Ce; the light yield measured in LuAG:Ce (0.55 at%) was about 26000 ph/MeV, or close to that of LSO.     

On the Statistical Calibration of Physical Models

We introduce a novel statistical calibration framework for physical models, relying on probabilistic embedding of model discrepancy error within the model. For clarity of illustration, we take the measurement errors out of consideration, calibrating a chemical model of interest with respect to a more detailed model, considered as “truth” for the present purpose. We employ Bayesian statistical methods for such model‐to‐model calibration and demonstrate their capabilities on simple synthetic models, leading to a well‐defined parameter estimation problem that employs approximate Bayesian computation. The method is then demonstrated on two case studies for calibration of kinetic rate parameters for methane air chemistry, where ignition time information from a detailed elementary‐step kinetic model is used to estimate rate coefficients of a simple chemical mechanism. We show that the calibrated model predictions fit the data and that uncertainty in these predictions is consistent in a mean‐square sense with the discrepancy from the detailed model data.