Metallic atoms and ions in comets: Comet Halley 1986 3

The origin of metallic atoms and ions in the cometary comae is investigated theoretically. Two effects are revealed in the comas of bright comets: (1) the Na anomalous type effect is possible within the gas-dust jets of comet P/Halley 1986 3 due to cooling cometary dust by cryogenic gas flow from the nucleus; and (2) the production of ions of refractory elements (Fe(+), Si(+), etc.) at large heliocentric distances is possible in the comas of the Halley type dusty comets due to high-velocity impacts between cometary and zodiacal dust particles. Spectral observations of comets with high sensitivity and spatial resolution are important for studying both comets and interplanetary dust

Interstellar dust as generator of x ray radiation

The x ray generation due to arising of hot dense plasma balls at high-velocity (greater than or equal to 70 km/s) collisions of dust grains in the interstellar medium is considered. Analytical expressions for efficiency of conversions of colliding dust particle kinetic energy into x ray radiation are presented. The observed intensity distribution of the diffuse component of soft cosmic x rays (0.1 to 1 keV) may be partly caused by collisions between the dusty components of high velocity clouds and of the disk of the Galaxy

New problems of cometary observations from space

The possibility of treating the comets as natural probes of the solar system presents one of the attractive sides of cometary astronomy. In connection with the plans to study comets from space, new aspects for comets as interplanetary probes are of interst. Possible meteor formation in cometary heads and the implication for space research are considered

Gravitating Sphaleron-Antisphaleron Systems

We present new classical solutions of Einstein-Yang-Mills-Higgs theory, representing gravitating sphaleron-antisphaleron pair, chain and vortex ring solutions. In these static axially symmetric solutions, the Higgs field vanishes on isolated points on the symmetry axis, or on rings centered around the symmetry axis. We compare these solutions to gravitating monopole-antimonopole systems, associating monopole-antimonopole pairs with sphalerons.Comment: 7 pages, 3 figure

On Necessary Conditions Of Basicity Of A System Of Eigen-Functions Of Second Order Discontinuous Operators

In the paper the basicity properties of a system of eigen-functions of the differential operator Lu = u 00+q (x) u are investigated, where q (x) is a complexvalued potential from the space L1 (0, 1). Following V.A.Ilin we proceed from the generalized treatment of eigen-functions and they can have discontinuity of the first order. The necessary conditions of basicity of a system of eigen-functions in the space Lp (1 < p < ∞) in terms of eigen-values are obtained

Determination of the Risk Factors Impact on the Construction Projects Implementation Using Fuzzy Sets Theory

The complexity of construction projects increases the likelihood of hazards affecting their successful implementation. There are many risk factors that lead to the failure of the project. These factors should be identified and ordered both because of their degree of importance (significance) and level (volume) of a given factors. This is very important in order to determine their effect on the construction project. Typically, the threats for the construction project include the extension of the project duration, the increase of the project cost and/or the reduce of the quality of the works. This article aims (1) to identify risk factors that may affect the construction project in Poland in the above-mentioned aspects and (2) to prioritize the significance of those risk factors. Due to the uniqueness of individual construction projects, the potential hazards and their effects are usually characterized by different levels of uncertainty. Unfortunately, it is often a non-statistical uncertainty. For this reason, the degree of significance of risk factors is described and modelled using linguistic variables and elements of the theory of fuzzy sets. This method allows to evaluate the risk of construction projects prior to their implementation