RESUMO
Energy circulation in geospace lies at the heart of space weather research. In the inner magnetosphere, the steep plasmapause boundary separates the cold dense plasmasphere, which corotates with the planet, from the hot ring current/plasma sheet outside. Theoretical studies suggested that plasmapause surface waves related to the sharp inhomogeneity exist and act as a source of geomagnetic pulsations, but direct evidence of the waves and their role in magnetospheric dynamics have not yet been detected. Here, we show direct observations of a plasmapause surface wave and its impacts during a geomagnetic storm using multi-satellite and ground-based measurements. The wave oscillates the plasmapause in the afternoon-dusk sector, triggers sawtooth auroral displays, and drives outward-propagating ultra-low frequency waves. We also show that the surface-wave-driven sawtooth auroras occurred in more than 90% of geomagnetic storms during 2014-2018, indicating that they are a systematic and crucial process in driving space energy dissipation.
RESUMO
AIM: To study the effect of recombinant hirudin (rH) on tPA-induced fibrinolysis and the possible mechanism of its action. METHODS: The effect of rH on thrombin-fibrin complex (Th-Fn) was detected by 99mTc labeled rH. In the in vitro clot lysis, tPA as plasminogen activator, and recalcified plasma as plasminogen resource were used to study the influence of rH on fibrinolysis by detecting TAFIa, D-Dimer and FXIII. RESULTS: In a canine model of femoral artery thrombosis, a clear radioactivity strip was imaged in 30 - 60 min on a part image, and the femoral vein thrombosis developed at 30 min. rH efficiently inhibited clot regeneration. Addition of TM could inhibit clot lysis obviously, and CPI could shorten the delay of clot lysis which due to TAFIa. There was a dose-dependent relationship with TM concentration and TAFI activation. FXIII activation was inhibited by low concentration of rH ( < or = 0.2 u x mL(-1)), and the level of fibrinolysis product, D-Dimer, increased. CONCLUSION: rH could inhibit the thrombin binding to fibrin. rH inhibited the activation of TAFI and FXIII by combining with thrombin which resulted in enhancement of thrombolysis.