A complete minimal system of covariants for the binary form of degree 7

A minimal system of 147 homogeneous generators of the algebra of covariants for the binary form of degree 7 is calculated.     

Powder Metallurgy Wear-Resistant Materials Based on Iron. Part 2. Materials Hot-Pressed from Porous Compacts

We continue our review of the data in the literature on the development of compositions and a technology for the manufacture of iron-based wear-resistant sintered materials. Analysis of the data shows that methods based on hot working of sintered porous compacts by pressure (hot forging, extrusion, etc.) are suitable for producing high-quality wear-resistant materials with superior strength and operating characteristics when working under high loads.     

Thickness effects of water overlayer on its explosive evaporation at heated metal surfaces

Molecular dynamics (MD) simulations have been employed to investigate the effect of the thickness of a water overlayer on the character of its ejection from a heated Au surface. The simulations are performed for five systems differing in the thickness of the water overlayer which was adsorbed on a metal substrate heated to 1000 K. For each system, an explosive evaporation occurs in the part of the water film adjacent to the metal surface and the upper part of the film is pushed off by the generated force. The average maximum temperature of the water film decreases as the film thickness increases. In contrast, the temperature achieved by the fast cooling due to the explosive evaporation shows an inverse trend. The significance of these model calculations to matrix-assisted laser desorption and ionization (MALDI) mass spectrometry is discussed.     

Psychological research of computer-mediated communication in Russia

The article is devoted to the earliest Russian research carried out in the computer-mediated communication field. The most important modern directions of psychological research in the computer mediated-communication field in Russia also are described. The first research direction deals with the educational effects of children and adults participation in the computer-mediated communication. The newest direction of psychological and sociological research is concentrated on analysing the dynamics of the networks' users population growth and change. This project is also devoted to the psychological results of computer-mediated communication. The structure of human activity, its orientation basis, emotional and motivational regulation were investigated. A special series of investigations is devoted to the gender differences in computer networking in Russia. The trends of future research in the computer-mediated communication field are also described.     

Towards a Dynamic Linkage of Example-based and Rule-based Machine Translation

This paper reports on a series of experiments which aim at integratingExample-based Machine Translation and Translation Memories with Rule-based Machine Translation. We start by examining the potentials of each MT paradigm in terms of system-internal and system-external parameters. Whereas the system-external parameters include the expected translation quality and translation coverage, system-internal parameters relate to adaptability and recall of translation units. We prefer a dynamic linkage of different MT paradigms where the sharing of labor amongst the modules involved, such as segmentation andsegment translation, is decided dynamically during runtime. We motivatethe communication of linguistically rich data structures between thedifferent components in a hybrid system and show that this linkage leadsto better translation results and improves the customization possibilitiesof the system.     

Origin of crystallization-induced refractive index changes in photo-thermo-refractive glass

Photo-thermo-refractive (PTR) glass is a multi-component silicate that undergoes localized refractive index decrease after UV-exposure and thermal treatment for partial crystallization. Based on this refractive index change, high efficiency volume Bragg gratings have been developed in PTR glass and have been successfully used for laser beam control. However, despite the fact that this type of glass has been widely studied and used over the last 20 years, the origin of the refractive index change upon crystallization is poorly understood. In this paper, we introduce three possible mechanisms (the precipitation of nano-sized NaF crystals and the associated local chemical changes of the glass matrix, the volumetric changes due to relaxation, and the local residual stresses) for the refractive index decrement in PTR glass and estimate the partial refractive index change due to each mechanism. Refractive index measurements are compared with high temperature XRD experiments and a general approach for the simulation of the refractive index change in PTR glass is proposed. We show that among the studied variables the residual stresses surrounding the crystals are the main responsible for the local refractive index decrement in this glass.     

Statistics of Capillary Waves on the Surface of Liquid Hydrogen in a Turbulent Regime

Excitation of the surface of liquid hydrogen by a harmonic force at low frequencies leads to the formation of turbulent cascade in the system of capillary waves. We have found that the probability density function for a high-frequency surface deviation from equilibrium state in the regime of developed turbulence is well approximated by the Gaussian distribution.      

Regulation of Ribosomal Protein Synthesis in Mycobacteria: The Autogenous Control of rpsO

The autogenous regulation of ribosomal protein (r-protein) synthesis plays a key role in maintaining the stoichiometry of ribosomal components in bacteria. In this work, taking the rpsO gene as a classic example, we addressed for the first time the in vivo regulation of r-protein synthesis in the mycobacteria M. smegmatis (Msm) and M. tuberculosis (Mtb). We used a strategy based on chromosomally integrated reporters under the control of the rpsO regulatory regions and the ectopic expression of Msm S15 to measure its impact on the reporter expression. Because the use of E. coli as a host appeared inefficient, a fluorescent reporter system was developed by inserting Msm or Mtb rpsO-egfp fusions into the Msm chromosome and expressing Msm S15 or E. coli S15 in trans from a novel replicative shuttle vector, pAMYC. The results of the eGFP expression measurements in Msm cells provided evidence that the rpsO gene in Msm and Mtb was feedback-regulated at the translation level. The mutagenic analysis showed that the folding of Msm rpsO 5′UTR in a pseudoknot appeared crucial for repression by both Msm S15 and E. coli S15, thus indicating a striking resemblance of the rpsO feedback control in mycobacteria and in E. coli.     

Loop heat pipe for cooling of high-power electronic components

In this paper, we present a new development of loop heat pipe (LHP) technology in its applications to cooling systems for high-power IGBT elements. An advanced method of LHP evaporator wick manufacturing has been proposed. Following this approach, a 16 mm outer diameter and 280 mm-length LHP evaporator was designed and manufactured. Nickel and titanium particles were used as raw material in LHP evaporator wick fabrication. LHP with a nominal capacity as high as 900 W for steady-state condition and more than 900 W for a periodic mode of operation at a temperature level below 100 °C and a heat transfer distance of 1.5 m was designed through the cooling of a high-power electronic module. An experimental program was developed to execute LHP performance tests and monitor its operability over a span of time. An investigation of the effects of LHP performance of parameters such as evaporator and condenser temperatures and LHP orientation in a gravity field was brought about. As regards the results of this initial series of tests, it was found that LHP spatial orientation within the nominal range of heat loads has no drastic effect on overall LHP functioning, whereas condenser temperature does play an important role, especially in the range of heat load close to critical. A 2D nodal model of the evaporator was developed and provides us with confirmation of the suggestion that when high-power dissipation levels are available, low wick conductivity is well adapted for LHP applications.