Risk which is common to an entire class of assets or liabilities. The value of investments may decline over a given time period simply because of economic changes or other events that impact large portions of the market.
Properties of the alpha-helix. 1  The structure repeats itself every 5.4 Angstroms along the helix axis, ie we say that the alpha-helix has a pitch of 5.4 Angstroms. Alpha-helices have 3.6 amino acid residues per turn, ie a helix 36 amino acids long would form 10 turns.
A helix is a twisted, spiral shape, like a corkscrew. In math, a helix is defined as a curve in three-dimensional space. If you have ever seen a spiral staircase, you can envision the shape of a helix. To picture the shape of a helix, imagine the coil of a spring inside a sofa, or the shape the threads of a screw make, curling in a spiral.