annulus

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annulus

[′an·yə·ləs]
(anatomy)
Any ringlike anatomical part.
(botany)
An elastic ring of cells between the operculum and the mouth of the capsule in mosses.
A line of cells, partly or entirely surrounding the sporangium in ferns, which constricts, thus causing rupture of the sporangium to release spores.
A whorl resembling a calyx at the base of the strobilus in certain horsetails.
(mathematics)
The ringlike figure that lies between two concentric circles.
(mycology)
A ring of tissue representing the remnant of the veil around the stipe of some agarics.
References in periodicals archive ?
After sending the lower front tooth to Wildlife Analytical Laboratory, the cementum annuli reading was 4 1/4 years old.
Ketchen (1975) developed an algorithm to estimate the number of missing annuli in the worn portion of the fin spine using the relationship between the enamel base diameter and the number of annuli counted on unworn worn fin spines.
Past studies have reported that Atlantic surfclams Spisula solidissima form one annulus per year in the fall, and thus annuli can be counted to determine the year class of the surfclam and final age can be assigned precisely relative to when the last annulus was formed (Almeida & Sheehan 1997).
Annuli were considered to consist of alternating pairs of opaque and translucent growth zones.
Because L annuli are considered, the energy accumulated in the battery of the harvester node [N.
In particular, an analysis of cementum annuli may be used to estimate age, or to develop population estimates through mark-recapture using a biomarker such as tetracycline (Matson and Kerr 1998).
clarkii, in Figure 3B-D, showing sample annuli from (B) the region near the origin of the aesthetasc array, (C) a region close to the center of the array, and (D) a region just proximal to the tip of the flagellum, the distal termination of the array.
Seven of 15 in group B and nine of 15 in group C annuli fibrosi showed in-growth of blood capillaries with unusual pairing of cells which is significant.
Each can provide advantages for a given species based on ease of collection, simplicity of processing, accuracy and precision of estimates of age, and difficulty of discerning annuli, especially at youngest and oldest ages (Chilton and Beamish, 1982; Beamish and McFarlane, 1983; Casselman, 1987).
This assumption has been proved to work reasonably well for flows through concentric annuli [13] for certain range of tubular diameter ratio.
5, p = 1, q = 1, r = 1, we observed an interesting scenario of the chaos development in the system: From the stationary state after doubling period bifurcation, the periodic regime with an attractor consisting of two points occurs, from which, in its turn, a quasiperiodic regime and an attractor of two annuli come up (see Figure 3.
Non-Newtonian flow in annuli is encountered in many situations of importance in a variety of industries and particularly in oil-well drilling.