DDR4 SDRAM computer buses have migrated towards replacing parallel buses with serial buses, for example by the evolution of Serial ATA replacing Parallel ATA, PCI Express replacing PCI, and serial ports replacing parallel ports. In general, serial buses are easier to scale up and have fewer wires/traces, making circuit boards using them easier to design. In the longer term, experts speculate that non-volatile RAM types like PCM (phase-change memory), RRAM (resistive random-access memory), or MRAM (magnetoresistive random-access memory) could replace DDR4 SDRAM and its successors. GDDR5 SGRAM is a graphics type of DDR3 synchronous graphics RAM, which was introduced before DDR4, and
Serial passage found. Notice that relatively few passages are necessary to produce a noticeable change in a virus; for instance, a virus can typically adapt to a new host within ten or so passages. In fact, exactly because serial passage allows for rapid evolution of a virus to its host, it can be used to study the evolution of antibiotic resistance; specifically, for determining what mutations could lead to the development of antibiotic resistance. The technique of serial passage has been around since the 1800s. In particular, Louis Pasteur’s work with the rabies vaccine in the late 1800s exemplifies this method. Pasteur