Library

Notes: Abstract. The analysis of 1988–1994 statistical data indicates that the population of Israel simultaneously moves in two opposite directions: while the initial distribution of new immigrants is primarily focused on the areas where jobs are available, the existing population of these areas tends to move outward, to the less populated districts where housing is more available and affordable. The paper thus argues that the heterogeneity of the population is indeed a crucial consideration for the proper modeling of migration behavior. It is also argued that a) the effect of housing construction on the patterns of in-country migration appears to be attenuated, and b) the low attractiveness of peripheral districts of the country to the new immigrants is mainly caused by a lack of jobs rather than by low rates of housing construction or the harsh climatic conditions of these areas.

Notes: Abstract The classical concept of the architecture of microbial murein assumes cross-linked glycan chains to be arranged in horizontal layers outside of the plasma membrane. It necessitates elaborate hypotheses to explain processes such as the biosynthesis, growth and division of the bacterial cell wall and provides no explanation for transenvelope macromolecular transport. Moreover, this model is difficult to reconcile with a number of basic chemical and electron microscopical data. According to a fundamentally distinct concept which is presented here, glycan strands in the microbial wall run perpendicular to the plasma membrane, each strand being cross-linked by peptide bridges with four other strands. This arrangement allows the formation of a structured matrix pierced with ordered ionophoric channels potentially harboring either lipoprotein or teichoic (lipoteichoic) acid molecules in Gram-negative and Gram-positive bacteria, respectively. New wall structures are synthesized in toto emerging from the cytoplasmic membrane as a condensed gel-like network below the old wall without being covalently attached to it, expanding due to inherent elasticity as the old wall is lyzed. This model reflects published genetic and biochemical data and offers a simple explanation for peptidoglycan biogenesis. As the biosynthesis is terminated by enzymic cleavage of all glycan strands, murein is irreversibly released from the membrane. The murein detachment prepares the membrane for de novo assembly of both the new wall synthesis machinery and the multicomponent factory for protein, DNA and phospholipid transfer. Being assembled in parallel, both new murein and the traffic complexes grow from the membrane together. This concept eliminates the necessity for the traffic complexes to penetrate intact murein. In the process of simultaneous assembly, the expanding murein functions as a lifting platform driven by the force of turgor pressure, transporting macromolecules through the perisplasmic space.

Notes: Summary Retinoids are known to modulate sebaceous gland activity in humans and animals. The nonpolar arotinoid Ro 15-0778 [(E)-1,2,3,4-tetrahydro-1,1,4,4-tetramethyl-6-(1-methyl-2-phenylethenyl) naphthalene] does not contain a polar end group and is devoid of the classical retinoid side effects of hypervitaminosis A. The favorable toxicological profile stimulated the evaluation of this arotinoid in animal models of sebum production. In castrated, testosterone-stimulated male rats, Ro 15-0778 is 50 times more potent than 13-cis-retinoic acid in inhibiting the production and subsequent secretion of sebum. The oral ED50 value of Ro 15-0778 is 30μg/kg, while an oral dose of 0.5 mg/kg inhibited sebum secretion nearly 1005. In testosterone-stimulated female rats, Ro 15-0778 inhibits sebum secretion significantly with an oral ED50 of 140 μg/kg and an s.c. ED50 of 75μg/kg. Ro 15-0778 was also evaluated for its ability to prevent testosterone induction of the immature hamster flank organ. The topical ED50 is 0.53 mg/kg and the oral ED50 is 38 mg/kg. This arotinoid is similarly active in mature male hamsters without testosterone treatment. In addition, the retinoid is active topically and orally in reducing the size of the gerbil abdominal sebaceous gland. The compound exhibits no antiandrogenic activity when tested in ventral prostrate and seminal vesicle assays in rats. Additionally, the compound does not have estrogenic activity when tested in the rat uterine weight assay. High doses of Ro 15-0778 in humans did not demonstrate significant sebumsuppressing activity. This study indicates that extra-polation of retinoid data from rodent animal models to activity in human sebaceous glands can not be made with a high degree of certainty. There is a need to develop new, more predictive models for retinoid activity.

Notes: Abstract It is shown that two canonical maps arising in the Poisson bracket formulations of elasticity and superfluids are particular instances of general canonical maps between duals of semidirect product Lie algebras.

Notes: This paper considers a rigorous thermodynamic approach that can be used for calculatinga variety of glass properties and the content of various structural units in glasses. Since both theproperties and the structure are calculated on a unified basis, this approach enables the structurepropertyrelationship in glasses to be established quantitatively, and the structural units thatcharacterise changes in glass properties to be determined

Notes: Electron beam technology (EB-PVD) and equipment for one-stage deposition of advancedgraded protective coatings using a composite ceramic ingot for evaporation are described. Thistechnology allows replacing the flat interface between coating layers by a graded transition zones andachieve of a high degree of reproducibility of the composition, structure and lifetime of thefunctionally graded coating in compare with traditional multi-stages technologies of protectivecoating deposition.A design of the composite ceramic ingot is considered, as well as the ability toregulate in a broad range the composition, structure and properties of all levels of the gradedprotective coating including transition zones and coating layers. Examples and variants of advancedgraded protective coatings with their structures and properties are given (thermal barrier, harderosion-resistant and damping coatings) for aerospace and gas-turbine industry application depositedby one-stage EB-PVD process. Total cost of one-stage EB-PVD deposition process at least 2 timesless in compare with traditional technological processes of protective coating deposition due to usingonly one EB-PVD unit and elimination of multistage nature of process cycle.Laboratory andproductive electron-beam units designed and manufactured at ICEBT are considered.Development of modern protective coatings, technologies and equipment for their application isfocused, primarily, on improvement of the durability and main service properties of thecoating/protected item system, ensuring a reliable reproducibility of the coating structure andproperties, shortening the cost and time of the entire technological cycle of their deposition. Theexisting traditional technologies of deposition of multilayer protective coatings, for instance, thermalbarrier coatings (TBC), containing a oxidation-resistant metal bond coat and outer lowthermal-conducting ceramic layer, are multi-stage, with combination of such processes as diffusionsaturation, galvanic coating, plasma spraying and electron beam deposition [1-3]. Use of diverseexpensive equipment, availability of intermediate mechanical and thermal treatments, as well as theoperations of surface cleaning, apply considerable limitations both on widening of the sphere of suchcoating application, and their further development in terms of improvement of the structure andproperties.The one-stage electron beam technology developed at ICEBT for deposition of advancedprotective coatings based on evaporation of a composite ingot and allowing deposition of functionallygraded coatings in one process cycle, meets the above goals to a considerable extent [4,5]. Thetechnology is based on the use of the known phenomenon of fractionating at evaporation ofmulticomponent systems, containing elements with different melting temperature and vapourpressure, and their subsequent condensation under vacuum, allowing the flat interface, for instancebetween the metal and ceramic layers, to be replaced by a transition zone of the graded compositionand structure.Fig.1 gives the schematic and appearance of a composite ingot used for one-stage deposition ofadvanced graded protective coatings in vacuum by its electron beam evaporation from one crucible.The ingot base material determines the purpose of the graded coating. For instance, Al2O3, TiC,TiB2, B4C, MgO, etc. can be used as the base of the ingot for deposition of hard wear-resistant,erosion-resistant and damping coatings. For the case of TBC, this is zirconium dioxide with additives