A head clamp for neurosurgery is described that includes a member for at least partially encircling the head of a subject. The inventive method combines the structure of a single-loop feedback control system and optimization search engine mechanisms. Register spill instructions that can be associated may be rewritten as parallel spill instructions, and the corresponding register spills may be configured for storage into memory in a manner permitting them to be loaded back to the registers in parallel. When the door is in a closed position, the free lateral walls of the seal rest against and are deflected outward on the door or on the muffle flange wall such that air is ousted from the sealing chambers, thus, causing the sealing chambers to function in a manner similar to that of a suction cup. The recombinant viruses are useful for evoking an immune response against the antigen.