2. The Carlitz-Witt suite 5 2.1. The classical ghost-Witt equivalence theorem . . . . . . . . . . . . . 5 2.2. Classical Witt vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . 7 2.3. The Carlitz ghost-Witt equivalence theorem . . . . . . . . . . . . . . 9 2.4. Carlitz-Witt vectors . . . . . . . . . . . . . . . . . . . . . . . . . . . . 12 2.5. F -modules . . . . . . . . . . . . . . ...

Ghost artifacts in echoplanar imaging (EPI) arise from phase errors caused by differences in eddy currents and gradient ramping during left-to-right traversal of kx(forward echo) versus right-to-left traversal of kx (reverse echo). Reference scans do not always reduce the artifact and may make image quality worse. To eliminate the need for reference scans, a ghost artifact reduction technique b...

Biologists routinely compare inferences about the order of evolutionary branching (phylogeny) with the order in which groups appear in the fossil record (stratigraphy). Where they conflict, ghost ranges are inferred: intervals of geological time where a fossil lineage should exist, but for which there is no direct evidence. The presence of very numerous and/or extensive ghost ranges is often be...

Adsorption of phages T4, T5, and BF23 to previously starved Escherichia coli cells triggered the immediate release of respiratory control. A similar stimulation of respiration was induced after T4 ghost attachment, showing that this process was independent of the mechanism of DNA injection. Rather, this change in the respiratory rate was related to the transient depolarization of the cytoplasmi...