Vocal group signatures in the goitred gazelle Gazella subgutturosa

Abstract The potential for vocal modification in mammals has recently been of great interest. This study focuses on the potential for vocal matching in juvenile and adolescent goitred gazelles Gazella subgutturosa that were group housed as part of an animal management programme. Two groups of animals (16 and 19 unrelated individuals, respectively) were recorded at two different ages, juvenile and adolescent, regarding 20-25 calls per individual per age; each group was evaluated in a separate year. Vocal similarity of group members compared to nonmembers was prominent in both ages, but higher in juveniles. Individual identity was prominent in both ages and higher in adolescents. The more prominent vocal indicators of group membership in juveniles could be related to their higher social dependence compared to adolescents. The more individualized calls of adolescents could be a mechanistic consequence of more stable growth at older age. Our results suggest vocal plasticity of goitred gazelles under social influences. These data add to recent evidence about domestic goat kids Capra hircus, suggesting that vocalizations of species that are not capable of imitation are more flexible than previously thought

Study of the effect of synthesis temperature and thermal aging on structural, dielectric properties and phase composition in NiO/NiAl2O4 composite ceramics

In modern materials science, a considerable amount of research is focused on obtaining new ceramic materials to create efficient functional elements. Acquiring highly efficient and stable ceramic catalysts for alternative energy is an important task that demands an urgent solution. Solving this problem as fast as possible is essential, as it will facilitate the development of new technologies that can prevent future energy crises. Nickel oxide (NiO) and spinel with the composition NiAl _2 O _4 are excellent candidates as high temperature catalysts used in alternative energy applications. This paper studies the synthesis of NiO/NiAl _2 O _4 composite ceramics and the effect of high-temperature aging on their phase composition, crystalline properties, and dielectric characteristics. The study found that the phase composition and microstructure of the ceramics remain unchanged after several thermal aging cycles at 700 °C. However, the crystalline parameters and low-frequency dielectric characteristics may fluctuate significantly depending on the duration of aging. The observed variations were predominantly influenced by the microstructural features of the composite ceramics. As the average grain size increased and the phase transformations were completed, the crystalline parameters and low-frequency dielectric characteristics reached a stable state without further alteration. For NiO/NiAl _2 O _4 ceramics with a sintering temperature of 1500 °C, the highest shrinkage, low dielectric loss values and acceptable hardness were observed, indicating that the fabricated ceramics are suitable for mechanical processing. In general, the obtained composite ceramics show high temperature stability and are well-suited for use as functional elements in hydrogen energy applications