Towards the Theory of Non--Abelian Tensor Fields I

We present a triangulation--independent area--ordering prescription which naturally generalizes the well known path ordering one. For such a prescription it is natural that the two--form ``connection'' should carry three ``color'' indices rather than two as it is in the case of the ordinary one--form gauge connection. To define the prescription in question we have to define how to {\it exponentiate} a matrix with three indices. The definition uses the fusion rule structure constants.Comment: 22 pages, 18 figure

String theory and classical integrable systems

We discuss different formulations and approaches to string theory and $2d$ quantum gravity. The generic idea to get a unique description of {\it many} different string vacua altogether is demonstrated on the examples in $2d$ conformal, topological and matrix formulations. The last one naturally brings us to the appearance of classical integrable systems in string theory. Physical meaning of the appearing structures is discussed and some attempts to find directions of possible generalizations to ``higher-dimensional" models are made. We also speculate on the possible appearence of quantum integrable structures in string theory.Comment: lecture given at III Baltic Rim student seminar, Helsinki, September 1993} 33pp, late

Quantum matter wave dynamics with moving mirrors

When a stationary reflecting wall acting as a perfect mirror for an atomic beam with well defined incident velocity is suddenly removed, the density profile develops during the time evolution an oscillatory pattern known as diffraction in time. The interference fringes are suppressed or their visibility is diminished by several effects such as averaging over a distribution of incident velocities, apodization of the aperture function, atom-atom interactions, imperfect reflection or environmental noise. However, when the mirror moves with finite velocity along the direction of propagation of the beam, the visibility of the fringes is enhanced. For mirror velocities below beam velocity, as used for slowing down the beam, the matter wave splits into three regions separated by space-time points with classical analogues. For mirror velocities above beam velocity a visibility enhancement occurs without a classical counterpart. When the velocity of the beam approaches that of the mirror the density oscillations rise by a factor 1.8 over the stationary value.Comment: 5.2 pages, 6 figure

Prediction of the Material Composition of the VVER-type Reactor Burned Pellet with Use of Neutron-Physical Codes

The purpose of neutron-physical calculations is typically isotopic composition of the fuel elements. However, in solving materials science problems related to nuclear fuel, researchers are usually interested in elemental composition of the fuel pellets, because the chemical and thermal physic properties are the same for differentisotopes of one chemical element. Nevertheless, for modeling of the elemental composition one should perform calculation of the isotopic composition and carry out the summation over all isotopes of a given chemical element. The development of computational tools allows the use of improved methods and codes, which held the consequent solution of tasks of heat conduction, neutron transport, and kinetics ofnuclides transformation. Thus the calculations take into account the dependence of the thermal conductivity from the changing isotopic composition and fuel burnup. This allows to perform neutron-physical and thermal-physical calculations of the reactor with detailed temperature distribution, taking into account temperature dependence of thermal conductivity and other characteristics. This approach was applied to calculations of the fuel pellet of the VVER type reactor and calculation of its elemental composition. Keywords: materials science, elemental composition, fuel pellet

Proton structure corrections to electronic and muonic hydrogen hyperfine splitting

We present a precise determination of the polarizability and other proton structure dependent contributions to the hydrogen hyperfine splitting, based heavily on the most recent published data on proton spin dependent structure functions from the EG1 experiment at the Jefferson Laboratory. As a result, the total calculated hyperfine splitting now has a standard deviation slightly under 1 part-per-million, and is about 1 standard deviation away from the measured value. We also present results for muonic hydrogen hyperfine splitting, taking care to ensure the compatibility of the recoil and polarizability terms.Comment: 9 pages, 1 figur

Comparative analysis of the content of metals and ecotoxicants in the hair of 7-year-old girls, living in different environmental conditions

The investigation and the comparative analysis of the content of metals (ecotoxicants) in the hair of 7-year-old girls, attending the first grade of a comprehensive school, living in different environmental conditions, were carried out. In a modern industrial city with a developed petrochemical infrastructure, there are chemical substances in the air, which often exceed the maximum permissible concentration, and the prolonged exposure of toxic substances causes a change in the functional state of the developing organism. In the conditions of technogenic pollution of the environment, it is especially important to study the impact of metals and ecotoxicants, having a toxic effect on the human body. The scale of growth of modern production is so large, that the amount of substances, emitted per unit of time, is much greater than the amount, which can be neutralized by the environment. Based on the numerous observations, it can be stated, that children are particularly sensitive to the impact of unfavorable environmental factors. Growing organism is characterized by the lowest threshold of perception to the influence of pollutants, high reactivity to external influences, and the degree of its adaptive capacity depends on the age, gender and a number of other individual characteristics. Such experimental direction has an applied significance and is of great scientific and practical interest, since it reflects the general state of the organism and the morphofunctional status of children of the age under study, living in different environmental conditions. On this basis, the study of the content of metals and ecotoxicants in the hair of seven-year-old girls, attending the first grade of a comprehensive school, living in different environmental conditions, was carried out. The following methods were used in the study: biochemical, statistical and the method of directed selection of the contingent. In the process of the study it has been found, that environmental pollution is one of the causative factors of reducing the adaptive capacity of the body, and the peculiarities of hair chemical composition, in regards to the studied substances, are determined by the ecological conditions of living

The Boundary State Formalism and Conformal Invariance in Off-shell String Theory

We present a generalization of the boundary state formalism for the bosonic string that allows us to calculate the overlap of the boundary state with arbitrary closed string states. We show that this generalization exactly reproduces world-sheet sigma model calculations, thus giving the correct overlap with both on- and off-shell string states, and that this new boundary state automatically satisfies the requirement for integrated vertex operators in the case of non-conformally invariant boundary interactions.Comment: 19 pages, 0 figure