Power semiconductor manufacturers are offering IGBT modules with ever greater power densities. The limit is represented by the maximum power loss that can be dissipated; optimisation criteria are the packaging technology as well as the conduction and switching losses of the semiconductor chips. The high current density of the modules together with high switching speeds place increased demands o...

An active-clamping quad-flyback converter is proposed to achieve zero voltage switching (ZVS) for all power switches. The secondary sides of quad-flyback converter are connected in parallel to share the load current. Thus, the transformer copper losses and the conduction losses on the output diodes are reduced. Activeclamping part including one auxiliary switch and one clamp capacitor can relea...

OBJECTIVE To assess the effect of acute alterations in afterload by aortoiliac clamping, during peripheral vascular surgery, on left ventricular function. DESIGN Prospective examination of the left ventricular long axis and transmitral Doppler flow preoperatively and intraoperatively; before aortic clamping, during clamping and 5 min, 15 min, and 5 days after unclamping. SETTING A tertiary ...

The sliding beta clamp subunit of the DNA replication machinery in the bacterium Escherichia coli coordinates multiple functions in the cell beyond genome duplication. In this issue, Parks et al. (2009) find that the beta clamp interacts with the transposition protein TnsE to target the Tn7 transposon to discontinuously replicating DNA at the replication fork.