Composite structures are already in use in secondary parts of the Douglas MD-11 and are planned to be used in the new MD-12X. Plans also exist for their use in primary and secondary structures on the Boeing 777. Douglas’ proposed MD-XX may also incorporate composite materials into primary structures such as the wings and tail. Use of composites in these structures offers weight savings, corrosi...

background: rna molecules play many important regulatory, catalytic and structuralroles in the cell, and rna secondary structure prediction with pseudoknots is one themost important problems in biology. an rna pseudoknot is an element of the rna secondary structure in which bases of a single-stranded loop pair with complementary basesoutside the loop. modeling these nested structures (pseudokno...

Tethered cord syndrome is a clinical phenomenon resulting from anatomic restriction of the normal movement of the spinal cord or vascular compromise leading to hypoxia of its distal structures. Tethering can be acquired (secondary) or congenital (primary). This article presents the relevant embryology, primary and secondary causes of tethering, clinical presentations, the treatment of specific ...