Dust extinction and absorption: the challenge of porous grains

In many models of dusty objects in space the grains are assumed to be composite or fluffy. However, the computation of the optical properties of such particles is still a very difficult problem. We analyze how the increase of grain porosity influences basic features of cosmic dust -- interstellar extinction, dust temperature, infrared bands and millimeter opacity. Porous grains can reproduce the flat extinction across the 3 - 8 \mkm wavelength range measured for several lines of sight by {\it ISO} and {\it Spitzer}. Porous grains are generally cooler than compact grains. At the same time, the temperature of very porous grains becomes slightly larger in the case of the EMT-Mie calculations in comparison with the results found from the layered-sphere model. The layered-sphere model predicts a broadening of infrared bands and a shift of the peak position to larger wavelengths as porosity grows. In the case of the EMT-Mie model variations of the feature profile are less significant. It is also shown that the millimeter mass absorption coefficients grow as porosity increases with a faster growth occurring for particles with Rayleigh/non-Rayleigh inclusions. As a result, for very porous particles the coefficients given by two models can differ by a factor of about 3. It is found that an increase of porosity leads to an increase of extinction cross sections at some wavelengths and a decrease at others depending on the grain model. However, this behaviour is sufficient to reproduce the extinction curve in the direction of the star $\sigma$ Sco using current solar abundances. In the case of the star $\zeta$ Oph our model requires larger amounts of carbon and iron in the dust-phase than is available.Comment: Astronomy and Astrophysics (accepted; 11 pages, 11 figures

The application of simultaneous recording of electrical conductivity and DTA in the study of binary and ternary salt systems

The advantages of the simultaneous recording of electrical conductivity curve and DTA curves in the investigation of salt mixtures is demonstrated on a number of examples. With sufficiently slow recording, at a heating rate of 5-10°/min, all the changes occurring in the mixture investigated, and connected with the differing electrical conductivities of the different phases which appear and disappear in the process of heating or cooling, are well reflected on the electrical conductivity curve. © 1972 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest

Influence of Geometric Parameters of an Acoustic Piston Supercharger on its Operating Efficiency

© 2017 Springer Science+Business Media New YorkThe influence of the geometric parameters of an acoustic piston gas supercharger on its operating efficiency is considered. An estimate of the capacity of the supercharger in a resonance operating regime is presented

Caused by Kozyavkin© method changes in hand function parameters in children with spastic form of cerebral palsy and their EEGs, HRVs and GDVs accompaniments

Background. Earlier we reported that in children with spastic forms of cerebral palsy (SFCP) after two-week course of rehabilitation by Kozyavkin© method the hand function tests changed ambiguously and such a variety of changes is due to differently directed changes in the background activity of the nerve centers. Aime: to identify the peculiarities of changes in the parameters of EEG, HRV and GDV in children with favorable and unfavorable changes in the parameters of the functions of the hands. Material and research methods. The object of observations were 14 children (6 girls and 8 boys) aged 8÷15 years with SFCP. State motor development at GMFCS was on II÷IV level. Functional status of the hand with MACS was at II÷III level. The estimation of hand function carried out by Dynamometry (D), Box and Block Test (BB) and Nine Hole Peg Test (NHP). We registered also components of muscular tone by device “NeuroFlexor” (Aggero MedTech AB, Sweden), HRV and EEG parameters simultaneosly by hardware-software complex “Cardiolab+VSR” and “NeuroCom Standard” respectively (KhAI Medica, Kharkiv, Ukraine) as well as GDV parameters by “GDV Chamber” (“Biotechprogress”, St-Pb, RF). Results. The method of cluster analysis retrospectively highlighted two distinct groups-clusters. In 9 children, rehabilitation led to favorable changes in the parameters of the function of the hands, while in 3 children they turned out to be unfavorable. The method of discriminant analysis revealed that unfavorable changes are accompanied by a decrease in the asymmetry of the θ- and δ-rhythms, the spectral power density (SPD) of β-rhythm in loci F8 and Fp1, instead, it increases in loci O1 and T3, leading to left-sided lateralization of the β-rhythm. At the same time, the SPD of the α-rhythm in locus O1 and the θ-rhythm in locus F4 rises as well as its Deviation. These changes in the EEG are accompanied by a reduction in vagalis and an increase in sympathetic tones. Among the GDVs parameters, an increase in the area of the GD Image in the frontal projection, coupled with a decrease in its Entropy in the frontal and left projections, was found. Instead, favorable changes in the parameters of the hand function are accompanied by opposite changes in the listed EEGs, HRVs and GDVs parameters or their absence. Conclusion. Among 14 observed children with spastic forms of cerebral palsy caused by Kozyavkin© method changes in functional tests of hand are favorable in 11. Adverse changes in 3 children are accompanied by characteristic changes in a number of EEGs, HRVs and GDVs parameters, which in the long run will be corrected by electrostimulation of the corresponding nervous structures

The application of simultaneous recording of electrical conductivity and DTA in the study of binary and ternary salt systems

The advantages of the simultaneous recording of electrical conductivity curve and DTA curves in the investigation of salt mixtures is demonstrated on a number of examples. With sufficiently slow recording, at a heating rate of 5-10°/min, all the changes occurring in the mixture investigated, and connected with the differing electrical conductivities of the different phases which appear and disappear in the process of heating or cooling, are well reflected on the electrical conductivity curve. © 1972 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest

The application of simultaneous recording of electrical conductivity and DTA in the study of binary and ternary salt systems

The advantages of the simultaneous recording of electrical conductivity curve and DTA curves in the investigation of salt mixtures is demonstrated on a number of examples. With sufficiently slow recording, at a heating rate of 5-10°/min, all the changes occurring in the mixture investigated, and connected with the differing electrical conductivities of the different phases which appear and disappear in the process of heating or cooling, are well reflected on the electrical conductivity curve. © 1972 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest

The application of simultaneous recording of electrical conductivity and DTA in the study of binary and ternary salt systems

The advantages of the simultaneous recording of electrical conductivity curve and DTA curves in the investigation of salt mixtures is demonstrated on a number of examples. With sufficiently slow recording, at a heating rate of 5-10°/min, all the changes occurring in the mixture investigated, and connected with the differing electrical conductivities of the different phases which appear and disappear in the process of heating or cooling, are well reflected on the electrical conductivity curve. © 1972 Wiley Heyden Ltd., Chichester and Akadémiai Kiadó, Budapest

Influence of Geometric Parameters of an Acoustic Piston Supercharger on its Operating Efficiency

© 2017 Springer Science+Business Media New YorkThe influence of the geometric parameters of an acoustic piston gas supercharger on its operating efficiency is considered. An estimate of the capacity of the supercharger in a resonance operating regime is presented

Influence of Geometric Parameters of an Acoustic Piston Supercharger on its Operating Efficiency

© 2017 Springer Science+Business Media New YorkThe influence of the geometric parameters of an acoustic piston gas supercharger on its operating efficiency is considered. An estimate of the capacity of the supercharger in a resonance operating regime is presented