CPLD控制的便携式电疗仪的刺激器设计

介绍了一种便携式电疗仪的刺激器的设计方法。利用CPLD芯片实现刺激器的主要硬件电路的设计,通过对CPLD芯片编程实现刺激波形的产生、刺激频率、脉宽和幅度的数字式可调。该方法简化了电路,提高了系统的实时处理能力和可扩展性。经仿真和电路测试证明,刺激器输出波形准确可靠,能很好满足各项性能要求。     

PCR jumping in clones of 30-million-year-old DNA fragments from amber preserved termites (Mastotermes electrodominicus)

DNA from 30-million-year-old amber preserved termites (Mastotermes electrodominicus) was PCR amplified with nuclear ribosomal RNA small subunit primers and cloned into the TA vector (INVITROGEN). We obtained several classes of recombinant clones as a result. AuthenticMastotermes electrodominicus clones were identified. The source of other classes of clones was identified as contaminants of the ancient DNA template. Several of the clones appeared to be chimeric in structure with half of the clone identical to the termite sequence and the other half identical to contaminant sequences. The phenomenon of PCR jumping was identified as a possible source for the chimeric clones.