Marker


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marker

[′märk·ər]
(immunology)
Any antigen that serves to distinguish cell types.
(ordnance)
A sign or signal for marking a location on land or water; frequently contains pyrotechnics.

Marker

 

a device for guiding a sower or planter to form interrows of a planned width. A marker consists of an extendable bar connected by a hinge to a sower or hitch. On the outer end of the bar is a disk, which is mounted at an angle and rotates freely; as it moves over the field, it leaves a furrow in the un-seeded area. On the next pass of the unit the furrow is used to guide the right front wheel or the inside edge of the right track of a tractor. Sowers and planters usually operate with right and left markers. The overlap (M) of the marker is determined according to the following formulas:

where a is the distance between the front wheels or the inside edges of the tracks, B is the distance between the extreme colters of the sower, and C is the size of the interrow.


Marker

 

an attachment to a single- or double-row sower that ensures parallel rows of seeds in subsequent passes. A marker consists of a beam with a weight on the end; the beam is secured to the front of the tractor. The tractor is steered so that the weight of the marker is above the track left by the planter wheel or marker disk on the preceding pass. Markers are often made reversible so that they can be used on both sides of the tractor.

marker

A sign, plaque, or monument that designates a building, site of historic importance, or boundary.

marker

markerclick for a larger image
Distance to go markers on the sides of runway.
An object displayed above ground level in order to indicate an obstacle or delineate a boundary (ICAO). Markers should be frangible, and those located near a runway or taxiway should be sufficiently low to ensure clearance for propellers and the engine pods of jet aircraft. The various types of markers are the distance-to-go markers, unpaved runway-edge markers, stop-way-edge markers, taxiway-edge markers, taxiway centerline markers, boundary markers, and unpaved taxiway-edge markers.
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I have had reporters and friends ask me why I continue to be prominently involved in this battle, now that I have indication that I'll receive the proper marker," Stewart said.
The posts for post-mounted markers should be made from 24-gauge steel, aluminum or fiberglass.
In response to the skepticism of the medical establishment, Kobayashi submitted to a double-blind test of his marker system by the National Cancer Institute in the USA.
Marker and others devised a plan to keep the cats from livestock, and angry farmers.