Psychological Stability of Orphans in Crisis Situations

AbstractThe article presents the results of the study of psychological stability of orphans who survived abuse and violence in the parental home (N = 120). The structure of psychological stability of children and adolescents in difficult situations (cognitive, emotional, behavioral, presentational) has been specified. According to the results of the study some groups of orphans have been identified by levels of psychological stability (psychologically stable, with an average degree of psychological stability, with a low degree of psychological stability, psychologically instable, with situational stability/ instability). There has been defined the relationship between personal characteristics and protective coping strategies used by orphans. The article shows the dependence of the psychological stability of orphans on the level of personal anxiety, inner tension, the level of sociability and self-presentation in the society. The features of the self-concept of orphans who survived abuse and violence in the parental home have been analyzed

Self consistent kinetic simulations of SPT and HEMP thrusters including the near-field plume region

The Particle-in-Cell (PIC) method was used to study two different ion thruster concepts - Stationary Plasma Thrusters (SPT) and High Efficiency Multistage Plasma Thrusters (HEMP-T), in particular the plasma properties in the discharge chamber due to the different magnetic field configurations. Special attention was paid to the simulation of plasma particle fluxes on the thrusters channel surfaces. In both cases, PIC proved itself as a powerful tool, delivering important insight into the basic physics of the different thruster concepts. The simulations demonstrated that the new HEMP thruster concept allows for a high thermal efficiency due to both minimal energy dissipation and high acceleration efficiency. In the HEMP thruster the plasma contact to the wall is limited only to very small areas of the magnetic field cusps, which results in much smaller ion energy flux to the thruster channel surface as compared to SPT. The erosion yields for dielectric discharge channel walls of SPT and HEMP thrusters were calculated with the binary collision code SDTrimSP. For SPT, an erosion rate on the level of 1 mm of sputtered material per hour was observed. For HEMP, thruster simulations have shown that there is no erosion inside the dielectric discharge channel.Comment: 14 pages, 11 figures This work was presented at 21st International Conference on Numerical Simulation of Plasmas (ICNSP'09

New features of surface plasmon resonance detected by modulation of electromagnetic radiation polarization

Using a technique based on modulation of electromagnetic radiation polarization, we studied the features of surface plasmon resonance in gold nanofilms deposited onto the surface of a totally reflecting prism (fused quartz). The angular characteristics of the polarization difference of squares of the reflectance coefficient modules for s- and p-polarized radiation, ∆ρ =|Rs|² − |Rp|² , were measured (at a wavelength λ = 0.63 µm) for metal films whose thickness varied from 0 up to 120 nm. Contrary to the results given by the traditional techniques, the characteristics of ∆ρ peak under the resonance condition. As a result, two nonresonance components were found in these characteristics. The values and shapes of their angular dependences are determined by the coefficients of internal reflection from the metal and insulator that depend on the film thickness. Application of a model with exponential dependence of the refraction and extinction coefficients on the metal film thickness led to agreement between the results of calculation from the Fresnel formulas and those obtained experimentally. It was found that characteristic parameter of the exponential corresponds to the metal film thickness value of 11±0.5 nm

Swelling and mechanical properties of alginate hydrogels with respect to promotion of neural growth

Soft alginate hydrogels support robust neurite outgrowth, but their rapid disintegration in solutions of high ionic strength restricts them from long-term in vivo applications. Aiming to enhance the mechanical stability of soft alginate hydrogels, we investigated how changes in pH and ionic strength during gelation influence the swelling, stiffness, and disintegration of a three-dimensional (3D) alginate matrix and its ability to support neurite outgrowth. Hydrogels were generated from dry alginate layers through ionic crosslinks with Ca(2+) (<=10 mM) in solutions of low or high ionic strength and at pH 5.5 or 7.4. High- and low-viscosity alginates with different molecular compositions demonstrated pH and ionic strength-independent increases in hydrogel volume with decreases in Ca(2+) concentrations from 10 to 2 mM. Only soft hydrogels that were synthesized in the presence of 150 mM of NaCl (Ca-alginateNaCl) displayed long-term volume stability in buffered physiological saline, whereas analogous hydrogels generated in NaCl-free conditions (Ca-alginate) collapsed. The stiffnesses of Ca-alginateNaCl hydrogels elevated from 0.01 to 19 kPa as the Ca(2+)-concentration was raised from 2 to 10 mM; however, only Ca-alginateNaCl hydrogels with an elastic modulus <=1.5 kPa that were generated with <=4 mM of Ca(2+) supported robust neurite outgrowth in primary neuronal cultures. In conclusion, soft Ca-alginateNaCl hydrogels combine mechanical stability in solutions of high ionic strength with the ability to support neural growth and could be useful as 3D implants for neural regeneration in vivo

The features of surface plasmon resonance in gold cluster films

The internal reflection of nanosized gold cluster films was studied using the technique of polarization modulation of electromagnetic radiation in the Kretschmann geometry. We measured the reflection coefficients Rs and Rp of s- and p-polarized radiation, respectively, as well as their polarization difference ∆R = Rs − Rp, as function of the light incidence angle in the 0.4÷1.6 µm wavelength range. A topological size effect was found; it consists in dependence of the value and sign of curvature of the polarization difference characteristics on the film surface properties. It is shown that the sign of curvature of ∆R characteristics depends on the radiation wavelength λ and indicates resonance interaction with a metal film of either p-polarized radiation only or that of both polarizations. The spectral characteristic of the topological size effect in the resonance interaction is obtained from the condition of isotropic reflection, ∆R = Rs − Rp = 0, and its dependence on the radiation wavelength