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.
References in periodicals archive ?
Some pictures were based on photographs taken by Simon himself, including a series called Out of Season comprising marker pen images of wrapped caravans, 50cms by 70cms, pounds 500 apiece.
Visitors will get seasonal crime-busting advice as well as security devices like ultraviolet marker pens.
Headteachers at St Joseph's and Hebburn Comprehensive schools have told pupils there is no need for students to use permanent marker pens and have banned them from school premises.
Passengers were given marker pens to fill in the appropriate station - and then they have to rely on the Christmas spirit of others to ensure that they get a nudge at the right time.
Teachers are banning permanent marker pens from schools in a bid to tackle graffiti.
Community partnership officer Elaine Hale, from Little Park Street police station, has 1,000 UV marker pens to give away to people who call into the police box in Smithford Way on Sunday.
PC Tony Gilroy, crime prevention officer, has a number of free marker pens for residents and businesses in Newcastle East.
She said: "Mr Maxwell has much to say about the subject of paedophelia but unfortunately he uses marker pens to express this on other people's property.
He said that security-marked property would also act as a deterrent to would-be thieves - and he suggested marker pens might figure on people's Christmas shopping list.
The packs include security marker pens, a crime prevention booklet, a burglary risk assessment guide and some Crimestoppers information.
Police are appealing to all garages and car dealerships in Nuneaton and Bedworth to contact them so they can be given free ultra-violet marker pens to give to customers.
He said: ``We will be introducing people to their local beat officers, offering crime prevention advice and giving out marker pens so people can mark their own property.