(n.) The order or arrangement of leaves on the stem; the science of the relative position of leaves.
Example Sentences:
(1) The symmetrical arrangements of monomers into such cylindrical structures as microfilaments of actin, flagella of bacteria, microtubules of many organisms, and the protein coats of viruses can be specified by citing the index numbers of two or three sets of contact parastichies, or helical ranks of monomers, as has been done in classical studies of phyllotaxis.
(2) In spiral phyllotaxis (3:2) a single angular discontinuity appears to be involved initially; the pertinent older leaves are three and five plastochrons older than the leaf being formed.
(3) This latter type of approach is put forward as being able to give a general framework in which to organize the concepts, results, and models in phyllotaxis in a way that produces a synergy of efforts.
(4) An algorithm, called the phi-model, based on the observation of the meaningful and symmetry-generating presence of the golden ratio phi in all types of spiral patterns, and consequently in all types of regular patterns in phyllotaxis, is proposed.
(5) The paper shows convergences between the results found in various models of phyllotaxis.
(6) The model is suggested by a property of the allometry-type model for pattern recognition in phyllotaxis.
(7) This pattern of expression has implications for how flo affects phyllotaxis, organ identity, and determinacy.
(8) The necessity of doing so is seen clearly when one considers that phyllotaxis-like patterns are encountered in other fields of research, so that the problem appears to transcend the strict botanical substratum.
(9) In whorled phyllotaxis two angular discontinuities appear to be involved with each new leaf; the pertinent older leaves are just one plastochron older than the leaf being initiated.
(10) It produces biophysically plausible schemes for the progressive development of various leaf structures and for the cyclical revision of apical structure seen in various types of phyllotaxis.
(11) The symmetry of alpha-helix subunit arrangement in the virion is related to the symmetry of leaf arrangement in plants (phyllotaxis) and is conserved in a molecular rearrangement model of the telescope.
(12) The phi-model is a link between the two entropy models in phyllotaxis and offers a nice correspondence with the minimal entropy model generated by a systemic and holistic approach.
(13) There are two major differences from previous theories of phyllotaxis.
(14) It shows that a synergic approach is needed to deal with the problems of phyllotaxis.
(15) However, in the literature it has not yet been honored as the basis for constructing the phyllotaxis in centric, planar models.
(16) Theory for leaf patterning, phyllotaxis, is usually expressed in terms of interactions in the surface of the apical dome of the shoot.
Stem
Definition:
(v. i.) Alt. of Steem
(n.) Alt. of Steem
(n.) The principal body of a tree, shrub, or plant, of any kind; the main stock; the part which supports the branches or the head or top.
(n.) A little branch which connects a fruit, flower, or leaf with a main branch; a peduncle, pedicel, or petiole; as, the stem of an apple or a cherry.
(n.) The stock of a family; a race or generation of progenitors.
(n.) A branch of a family.
(n.) A curved piece of timber to which the two sides of a ship are united at the fore end. The lower end of it is scarfed to the keel, and the bowsprit rests upon its upper end. Hence, the forward part of a vessel; the bow.
(n.) Fig.: An advanced or leading position; the lookout.
(n.) Anything resembling a stem or stalk; as, the stem of a tobacco pipe; the stem of a watch case, or that part to which the ring, by which it is suspended, is attached.
(n.) That part of a plant which bears leaves, or rudiments of leaves, whether rising above ground or wholly subterranean.
(n.) The entire central axis of a feather.
(n.) The basal portion of the body of one of the Pennatulacea, or of a gorgonian.
(n.) The short perpendicular line added to the body of a note; the tail of a crotchet, quaver, semiquaver, etc.
(n.) The part of an inflected word which remains unchanged (except by euphonic variations) throughout a given inflection; theme; base.
(v. t.) To remove the stem or stems from; as, to stem cherries; to remove the stem and its appendages (ribs and veins) from; as, to stem tobacco leaves.
(v. t.) To ram, as clay, into a blasting hole.
(v. t.) To oppose or cut with, or as with, the stem of a vessel; to resist, or make progress against; to stop or check the flow of, as a current.
(v. i.) To move forward against an obstacle, as a vessel against a current.
Example Sentences:
(1) However, CT will be insensitive in the detection of the more cephalic proximal lesions, especially those in the brain stem, basal cisterns, and skull base.
(2) Based on our results, we propose the following hypotheses for the neurochemical mechanisms of motion sickness: (1) the histaminergic neuron system is involved in the signs and symptoms of motion sickness, including vomiting; (2) the acetylcholinergic neuron system is involved in the processes of habituation to motion sickness, including neural store mechanisms; and (3) the catecholaminergic neuron system in the brain stem is not related to the development of motion sickness.
(3) The examination of the standard waves' amplitude and latency of the brain stem auditory evoked response (BAEP) was performed in 20 guinea pigs (males and females, weighing 250 to 300 g).
(4) A previous trial into the safety and feasibility of using bone marrow stem cells to treat MS, led by Neil Scolding, a clinical neuroscientist at Bristol University, was deemed a success last year.
(5) Proliferation of quiescent hematopoietic stem cells, purified by cell sorting and evaluated by spleen colony assay (CFU-S), was investigated by measuring the total cell number and CFU-S content and the DNA histogram at 20 and 48 hours of liquid culture.
(6) The last stems from trends such as declining birth rate, an increasingly mobile society, diminished importance of the nuclear family, and the diminishing attractiveness of professions involved with providing maintenance care.
(7) Following BHT administration, the alveolar stem cells (type II pneumocytes) proliferate and differentiate according to a biphasic pattern, with proliferative peaks at d 3 and 7.
(8) In testing the contribution of the long, curved stem to the torsional stability of uncemented prostheses by comparing it with other stems, the long, curved stem was the most stable, followed by a shorter straight stem, and a short, proximally curved stem.
(9) For example, stem pairing with a sequence other than wild-type resulted in normal protein binding in vitro but derepression of protein synthesis in vivo.
(10) These results indicate that this population (approximately 0.1% of bone marrow) may contain the pluripotent hematopoietic stem cell.
(11) Brain-stem CBF varied the most but did not correlate with clinical signs of brain-stem dysfunction.
(12) We infer from these results that endotoxin ameliorates the cyclical changes in blood cell counts by regulating hematopoietic proliferative activity at the stem cell level.
(13) The effects of inhibitors of aldehyde dehydrogenase activity on the sensitivity of murine pluripotent hematopoietic stem cells to oxazaphosphorine anticancer agents, e.g.
(14) Three strains of fluorescent pseudomonads (IS-1, IS-2, and IS-3) isolated from potato underground stems with roots showed in vitro antibiosis against 30 strains of the ring rot bacterium Clavibacter michiganensis subsp.
(15) This has stemmed from an inadequate understanding of the mechanisms involved in the formation and propagation of this condition.
(16) We therefore think that the detailed examination of CALLA(-) non-T non-B ALL cells using myeloid specific antibodies is helpful in clarifying the characteristics of myeloid precursors and the common bipotential stem cell of lymphoid and myeloid progenitors.
(17) Imaging studies had shown no change in his brain stem lesion, which at autopsy was found to be a focal collection of fibrillary astrocytes.
(18) These cells were hypothesized to be the stem cells for the corneal epithelium.
(19) Auditory brain stem potentials (ABP) were recorded in 27 patients with Bell's palsy during the early phase of the disease and 1-3 months later.
(20) The results indicate that stimulation of trigeminal subnucleus caudalis, a brain stem region that processes nociceptor afferent information, evokes a prompt increase in plasma ACTH.