The Power Flow Angle of Acoustic Waves in Thin Piezoelectric Plates

The curves of slowness and power flow angle (PFA) of quasi-antisymmetric (A0) and quasi-symmetric (S0) Lamb waves as well as quasi-shear-horizontal (SH0) acoustic waves in thin plates of lithium niobate and potassium niobate of X-,Y-, and Z-cuts for various propagation directions and the influence of electrical shorting of one plate surface on these curves and PFA have been theoretically investigated. It has been found that the group velocity of such waves does not coincide with the phase velocity for the most directions of propagation. It has been also shown that S0 and SH0 wave are characterized by record high values of PFA and its change due to electrical shorting of the plate surface in comparison with surface and bulk acoustic waves in the same material. The most interesting results have been verified by experiment. As a whole, the results obtained may be useful for development of various devices for signal processing, for example, electrically controlled acoustic switchers

The characteristics of fundamental shear-horizontal acoustic waves in structure “nanocomposite polymeric film-vacuum gap-piezoelectric plate”

AbstractRecently it has been shown that SH0 wave in structure “piezoelectric plate-nanocomposite polymeric film with Fe nanoparticles” is characterized by the low TCD (∼15 ppm/C) and high value of K2 (∼32%). However in the case of the acoustical contact of polymeric material with the plate such structure possesses significant attenuation of the acoustic wave (∼1dB/λ). In order to avoid this effect it was suggested to use the structure containing the gap between the polymeric film and plate. As the result of theoretical analysis the dependencies of SH0 wave velocity versus relative thickness of vacuum gap were obtained. It has been found that there exist such values of gap and dielectric permittivity of the nanocomposite material when the value of TCD of SH0 wave significantly decreases. At that the attenuation connected with the dissipation factor is practically absent

Unstable Hadrons in Hot Hadron Gas in Laboratory and in the Early Universe

We study kinetic master equations for chemical reactions involving the formation and the natural decay of unstable particles in a thermal bath. We consider the decay channel of one into two particles, and the inverse process, fusion of two thermal particles into one. We present the master equations the evolution of the density of the unstable particles in the early Universe. We obtain the thermal invariant reaction rate using as an input the free space (vacuum) decay time and show the medium quantum effects on $\pi+\pi \leftrightarrow \rho$ reaction relaxation time. As another laboratory example we describe the $K+K \leftrightarrow \phi$ process in thermal hadronic gas in heavy-ion collisions. A particularly interesting application of our formalism is the $\pi^{0}\leftrightarrow \gamma +\gamma$ process in the early Universe. We also explore the physics of $\pi^{\pm}$ and $\mu^{\pm}$ freeze-out in the Universe.Comment: 13 pages, 9 figures, published in Physical Review

Students’ development in different educational systems

El artículo revela las conclusiones del trabajo experimental que se ha realizado para comparar tres sistemas educativos rusos (sistema tradicional, sistema de Zankov y el sistema de Elkonin-Davidov) en sus potencialidades para desarrollar las capacidades intelectuales y los rasgos de personalidad de los jóvenes estudiantes. El complejo de índices (habilidades intelectuales y rasgos de personalidad) ha sido identificado para examinar los sistemas educativos. Son los índices de atención, memoria, pensamiento, imaginación y rasgos de personalidad (motivo de logro, motivos de aprendizaje y empatía). Como resultado del experimento realizado del desarrollo de los estudiantes en los diferentes sistemas educativos se ha identificado que cada uno de estos sistemas examinados desarrolla diferentes funciones mentales y operaciones.The article reveals the findings of the experimental work that has been done in order to compare three Russian educational systems (traditional system, Zankov’s system and the system of Elkonin-Davidov) in their potentials to develop the junior schoolchild intellectual abilities and personality traits. The complex of indices (intellectual abilities and personality traits) has been identified to examine the educational systems. They are the indices of attention, memory, thinking, imagination and personality traits (achievement motive, learning motives and empathy). As a result of conducted experiment of the students’ development in different educational systems it has been identified that each of examined systems are ‘developmental’ however each develops different mental functions and operations.peerReviewe

Peltier effect in normal metal-insulator-heavy fermion metal junctions

A theoretical study has been undertaken of the Peltier effect in normal metal - insulator - heavy fermion metal junctions. The results indicate that, at temperatures below the Kondo temperature, such junctions can be used as electronic microrefrigerators to cool the normal metal electrode and are several times more efficient in cooling than the normal metal - heavy fermion metal junctions.Comment: 3 pages in REVTeX, 2 figures, to be published in Appl. Phys. Lett., April 7, 200

Sensitivity to amplitude envelope rise time in infancy and vocabulary development at 3 years: A significant relationship.

Here we report, for the first time, a relationship between sensitivity to amplitude envelope rise time in infants and their later vocabulary development. Recent research in auditory neuroscience has revealed that amplitude envelope rise time plays a mechanistic role in speech encoding. Accordingly, individual differences in infant discrimination of amplitude envelope rise times could be expected to relate to individual differences in language acquisition. A group of 50 infants taking part in a longitudinal study contributed rise time discrimination thresholds when aged 7 and 10 months, and their vocabulary development was measured at 3 years. Experimental measures of phonological sensitivity were also administered at 3 years. Linear mixed effect models taking rise time sensitivity as the dependent variable, and controlling for non-verbal IQ, showed significant predictive effects for vocabulary at 3 years, but not for the phonological sensitivity measures. The significant longitudinal relationship between amplitude envelope rise time discrimination and vocabulary development suggests that early rise time discrimination abilities have an impact on speech processing by infants.Australian Research Counci

Financing of infrastructure in education : international experience of attracting private investments and opportunities for Russia to form a knowledge-driven economy

The article substantiates the role of education, proposes and confirms the hypothesis about the importance and necessity of social partnerships for financing and development of education in knowledge- driven economy. To confirm the advanced hypotheses we studied the evolution of concepts of social interaction and social responsibility to justify patterns of social partnerships in the knowledge-driven economy that allowed us, using the model of "triple helix", to show the necessity of the collaboration of government, universities and corporations to advance on the path of innovative development. We considered the industrial districts as territories, which act as a space of coordination of actors, to whom the solution of new production problems is impossible without direct interaction with universities. The lack of budget funds for the development of education requires a search for other sources of funding for infrastructure facilities in education. We revealed the mechanisms of attraction of private funding of educational institutions in Russia, arising challenges, and possible solutions. The article considers the application of concession as a form of public – private partnerships in preschool education, which recently has found application in Russia. Based on studying world best practices, the authors propose to use the investment funds, in particular, the mechanism of impact investment in education as a promising technology. Improvement of Russian legislation concerning investment funds will create the foundation for wide application of exchange-traded mutual funds for collective investments in social infrastructure. Formation of trust funds and grants to finance education becomes widespread in Russia.peer-reviewe

Pairing state in multicomponent superconductors

We use the microscopic weak coupling theory to predict the pairing state in superconductors of cubic, hexagonal, or tetragonal symmetry, where the order parameter is multicomponent, i.e., transforms according to either a 2-dimensional or a 3-dimensional representation of the crystal point group. We show that the superconducting phase usually breaks the time-reversal symmetry for singlet multicomponent superconductors. The superconducting order parameter for triplet superconductors in most cases turns out to be non-magnetic.Comment: 7 page