Drive level dependency in quartz resonators

AbstractCommon piezoelectric resonators such as quartz resonators have a very high Q and ultra stable resonant frequency. However, due to small material nonlinearities in the quartz crystal, the resonator is drive level dependent, that is, the resonator level of activity and its frequency are dependent on the driving, or excitation, voltage. The size of these resonators will be reduced to one fourth of their current sizes in the next few years, but the electrical power which is applied will not be reduced as much. Hence, the applied power to resonator size ratio will be larger, and the drive level dependency may play a role in the resonator designs.We study this phenomenon using the Lagrangian nonlinear stress equations of motion and Piola–Kirchhoff stress tensor of the second kind. Solutions are obtained using COMSOL for the AT-cut, BT-cut, SC-cut and other doubly rotated cut quartz resonators and the results compared well with experimental data. The phenomenon of the drive level dependence is discussed in terms of the voltage drive, electric field, power density and current density. It is found that the drive level dependency is best described in terms of the power density. Experimental results for the AT-, BT- and SC-cut resonators in comparison with our model results are presented. Results for new doubly rotated cuts are presented. The effects of spurious modes, quality factor and air damping on DLD are presented

Effect of Thermoplastic Binder on Flow Deformation Behavior of Wood

AbstractA processing technique was recently developed to realize plastic deformation in wood impregnated with a thermoset binder. This paper proposes a new flow forming technique where a thermoplastic binder is used instead of a thermoset binder with the expectation that the formability and recyclability of the products will be improved. To clarify the effect of the thermoplastic binder on the flow deformation behavior of wood, capillary fluidity tests were performed using impregnated wood with various contents of thermoplastic binder (polymer). The extrusion load of the impregnated wood through the capillary decreased with an increase of the polymer content in the wood. Results of the second fluidity test using the first extruded material reveals that the recycled impregnated wood can flow again. The extrusion load of the second extrusion was equal to or lower than the first. These results indicate that the recyclability of the wood impregnated with a thermoplastic binder is highly promising. The internal configuration of the impregnated wood during extrusion was also dependent on the polymer content

Influence of pulsive pressure waves on liquid penetration into wood in semi-opened container

The purpose of this paper was to confirm the influence of pulsive pressure waves on the liquid penetration into wood in the semi-opened container. Wood block sample was irradiated by the pulsive pressure waves in the semi-opened container filled with water used as a liquid. The irradiation was also performed in the closed container for the comparison. The water penetration into the sample was promoted by the pressure-wave irradiation. There was little difference in the degree of the penetration between the closed and the semi-opened containers. It was presumed from the measured hydraulic pressure that the pressure-wave energy irradiated on the sample in the closed container was higher than that in the semi-opened container. It was also presumed that the cavitation generation was promoted in the semi-opened container. This indicates that the cavitation as well as the pressure waves themselves affected the liquid penetration into wood. The compressive deformation of the sample irradiated in the semi-opened container was slightly smaller than that in the closed container. This indicates that the pulsive pressure-wave irradiation in the semi-opened container promoted the liquid penetration into wood with less compressive deformation

The integration of audio−tactile information is modulated by multimodal social interaction with physical contact in infancy

Interaction between caregivers and infants is multimodal in nature. To react interactively and smoothly to such multimodal signals, infants must integrate all these signals. However, few empirical infant studies have investigated how multimodal social interaction with physical contact facilitates multimodal integration, especially regarding audio − tactile (A-T) information. By using electroencephalogram (EEG) and event-related potentials (ERPs), the present study investigated how neural processing involved in A-T integration is modulated by tactile interaction. Seven- to 8-months-old infants heard one pseudoword both whilst being tickled (multimodal ‘A-T’ condition), and not being tickled (unimodal ‘A’ condition). Thereafter, their EEG was measured during the perception of the same words. Compared to the A condition, the A-T condition resulted in enhanced ERPs and higher beta-band activity within the left temporal regions, indicating neural processing of A-T integration. Additionally, theta-band activity within the middle frontal region was enhanced, which may reflect enhanced attention to social information. Furthermore, differential ERPs correlated with the degree of engagement in the tickling interaction. We provide neural evidence that the integration of A-T information in infants’ brains is facilitated through tactile interaction with others. Such plastic changes in neural processing may promote harmonious social interaction and effective learning in infancy

Role of fibroblast growth factor 8 (FGF8) in animal models of osteoarthritis

10.1186/ar2474Arthritis Research and Therapy104R9

Species diversity and abundance of seagrasses in southwestern Thailand under different influence of river discharge

Seagrass beds are among the most important components in coastal ecosystem, but are susceptible to human-induced changes in terrestrial ecosystem. As a first step to understand the effects of terrestrial input through river discharge on tropical seagrass ecosystems, we carried out quantitative mapping of seagrass beds at Pang-gna and Trang Provinces, southwestern Thailand to examine spatial variation in species composition, species diversity and biomass of seagrasses. Five seagrass beds were chosen as study sites that locate at different distances from the major river mouths, and thus subjected to different impacts of river discharge. These seagrass beds differed greatly in environmental conditions, seagrass diversity and abundance. Seagrass beds located near large river mouths showed higher silt-clay content in the sediments and light attenuation of water, possibly due to transportation of sediment from rivers and its resuspension. A total of nine seagrass species occurred. Enhalus acoroides and Halophila ovalis occurred in all the stations, whereas distribution of other species were mostly confined to seagrass beds with small or moderate degree of siltation and light attenuation. Seagrass species diversity measured by species richness and Simpson\u27s diversity index was lower in seagrass beds near the river mouth. These findings highlight negative impacts of terrestrial ecosystems through river discharge on seagrass biodiversity and its functioning along the coastal areas of southwestern Thailand

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Discussion enables us to respect each kindergarten child\u27s opinion, and it allows them to realize self-esteem. At the same time, communication among kindergarten children can be deepened through discussion. Consequently, discussion will develop into new and creative experiences for them. I will deal with a case study of a kindergarten, which historically, has placed much emphasis on discussion. Through this study, I will investigate the correlation between discussion and a course of study in kindergartens. In addition, I will study the background to help better foster the art of discussion