This happens about 2-3% of the time in people with celiac disease and can lead to false-negative test results. Common tests for celiac disease include: 1  Anti-tissue transglutaminase antibody (anti-tTG), IgA: detects antibodies to tissue transglutaminase, an enzyme that causes the crosslinking of certain proteins. 2  Anti-tTG, IgA is the most sensitive and specific blood test for celiac disease.
A contour line is a line drawn on a topographic map to indicate ground elevation or depression. A contour interval is the vertical distance or difference in elevation between contour lines. Index contours are bold or thicker lines that appear at every fifth contour line.
The contour interval of a topographic map is the difference in elevation between successive contour lines. Contour or isarithmic maps can be used to show a variety of phenomena such as precipitation, temperature, atmospheric pressure, or solar radiation. Data used in isarithmic maps are not confined to predefined political or geographic boundaries. Rather, the data's parameters are as varied as its environment. More generally, a contour line for a function of two variables is a curve connecting points where the function has a same particular value.