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 shape formed by a smooth curve. To visualize this shape, one can imagine a ribbon wound around a stick, or the spiral cord between a telephone handset and its base. A spiral staircase is another practical example.