RESUMO
The temperature control system is one of the most important subsystems of the strapdown airborne gravimeter. Because the quartz flexible accelerometer based on springy support technology is the core sensor in the strapdown airborne gravimeter and the magnet steel in the electromagnetic force equilibrium circuits of the quartz flexible accelerometer is greatly affected by temperature, in order to guarantee the temperature control precision and minimize the effect of temperature on the gravimeter, the SGA-WZ temperature control system adopts a three-level control method. Based on the design experience of the SGA-WZ-01, the SGA-WZ-02 temperature control system came out with a further optimized design. In 1st level temperature control, thermoelectric cooler is used to conquer temperature change caused by hot weather. The experiments show that the optimized stability of 1st level temperature control is about 0.1 °C and the max cool down capability is about 10 °C. The temperature field is analyzed in the 2nd and 3rd level temperature control using the finite element analysis software ANSYS. The 2nd and 3rd level temperature control optimization scheme is based on the foundation of heat analysis. The experimental results show that static accuracy of SGA-WZ-02 reaches 0.21 mGal/24 h, with internal accuracy being 0.743 mGal/4.8 km and external accuracy being 0.37 mGal/4.8 km compared with the result of the GT-2A, whose internal precision is superior to 1 mGal/4.8 km and all of them are better than those in SGA-WZ-01.
RESUMO
Neuronal ion channels of different types often do not function independently but will inhibit or potentiate the activity of other types of channels, a process called cross-talk. The N-methyl-D-aspartate receptor (NMDA receptor) and the γ-aminobutyric acid type A receptor (GABA(A) receptor) are important excitatory and inhibitory receptors in the central nervous system, respectively. Currently, cross-talk between the NMDA receptor and the GABA(A) receptor, particularly in the central auditory system, is not well understood. In the present study, we investigated functional interactions between the NMDA receptor and the GABA(A) receptor using whole-cell patch-clamp techniques in cultured neurons from the inferior colliculus, which is an important nucleus in the central auditory system. We found that the currents induced by aspartate at 100 µmol L(-1) were suppressed by the pre-perfusion of GABA at 100 µmol L(-1), indicating cross-inhibition of NMDA receptors by activation of GABA(A) receptors. Moreover, we found that the currents induced by GABA at 100 µmol L(-1) (I (GABA)) were not suppressed by the pre-perfusion of 100 µmol L(-1) aspartate, but those induced by GABA at 3 µmol L(-1) were suppressed, indicating concentration-dependent cross-inhibition of GABA(A) receptors by activation of NMDA receptors. In addition, inhibition of IGABA by aspartate was not affected by blockade of voltage-dependent Ca(2+) channels with CdCl(2) in a solution that contained Ca(2+), however, CdCl(2) effectively attenuated the inhibition of I (GABA) by aspartate when it was perfused in a solution that contained Ba(2+) instead of Ca(2+) or a solution that contained Ca(2+) and 10 mmol L(-1) BAPTA, a membrane-permeable Ca(2+) chelator, suggesting that this inhibition is mediated by Ca(2+) influx through NMDA receptors, rather than voltage-dependent Ca(2+) channels. Finally, KN-62, a potent inhibitor of Ca(2+)/calmodulin-dependent protein kinase II (CaMKII), reduced the inhibition of I (GABA) by aspartate, indicating the involvement of CaMKII in this cross-inhibition. Our study demonstrates a functional interaction between NMDA and GABA(A) receptors in the inferior colliculus of rats. The presence of cross-talk between these receptors suggests that the mechanisms underlying information processing in the central auditory system may be more complex than previously believed.
