Dynamic collimator and dose rate control: enabling technology for enhanced dynamic wedge.

The key features that make dynamic dose delivery possible in the Enhanced Dynamic Wedge application are computerized position and control of the independent collimating jaws and computerized dynamic control of the linear accelerator dose rate. These features will be described and related to the current implementation of Enhanced Dynamic Wedge.

Amino acid periodicities and their structural implications for the evolutionarily conservative central domain of some silkmoth chorion proteins.

The central domain is an evolutionarily conservative region that is invariant in length in the A and Hc-A families of silkmoth chorion proteins. This domain shows strong sixfold periodicities for various amino acid residues, such as glycine and large non-polar residues. The periodicities and their phase relationships, together with the documented prevalence of beta-sheets and beta-turns in the chorion, strongly support a secondary structure model in which short (4-residue) beta-sheet strands alternate with beta-turns, forming a compact antiparallel, probably twisted beta-sheet. This structure should be important for the establishment of higher order structure in the chorion.