Category: N

Any device or electrode that improves function by substituting for an injured or diseased part of the nervous system.  

A prism made by splitting a prism of Icelandic spar and rejoining the cut surfaces. This causes the light passing through to be split. Ordinary light rays are reflected by the joined surfaces, and polarized light is transmitted.  

Any pressure less than that of the atmosphere, or less than that pressure to which the initial pressure is being compared. The suction force or the lack of pressure.  

Pain and stiffness in the muscles of the axial skeleton, especially of the neck and back; mild fever; increased proteins and leukocytes in the cerebrospinal fluid. Diagnosis depends on the isolation of the virus and serological reactions.  

Injury sustained from contact with nitric acid. Symptoms include pain, burning, vomiting, thirst, and shock.  

Poisoning caused by narcotic or sleep-producing drugs such as opium and its derivatives.  

Either of a pair of points situated on the axis of an optical system so that any incident ray sent through one will produce a parallel emergent ray sent through the other.  

Pneumonia occurring after 48 hours of confinement in a hospital, intensive care unit, or nursing home. It is often the result of infection with gram-negative pathogens or multiply drug-resistant bacteria.  

Lung infection occurring in the first few days of life due to uterine exposure to infectious microorganisms or to infection during or immediately after birth. Common causes include viruses (e.g., herpes simplex) and bacteria (e.g., group B streptococcus, Chlamydia, Escherichia coli, Listeria).  

Pooled plasma from a number of human donors. The plasma is selected from screened donors and sterilized.