(a.) Extinguished; put out; quenched; as, a fire, a light, or a lamp, is extinct; an extinct volcano.
(a.) Without a survivor; without force; dead; as, a family becomes extinct; an extinct feud or law.
(v. t.) To cause to be extinct.
Example Sentences:
(1) The stages of mourning involve cognitive learning of the reality of the loss; behaviours associated with mourning, such as searching, embody unlearning by extinction; finally, physiological concomitants of grief may influence unlearning by direct effects on neurotransmitters or neurohormones, such as cortisol, ACTH, or norepinephrine.
(2) The effect upon ethanol responding was found not to resemble a pattern of extinction, but rather was best described as a general overall reduction in responding.
(3) In a recent study, Orr and Lanzetta (1984) showed that the excitatory properties of fear facial expressions previously described (Lanzetta & Orr, 1981; Orr & Lanzetta, 1980) do not depend on associative mechanisms; even in the absence of reinforcement, fear faces intensify the emotional reaction to a previously conditioned stimulus and disrupt extinction of an acquired fear response.
(4) We conclude that the procedure used in this study is a non-intrusive intervention that is an extension of the current literature pertaining to sensory extinction.
(5) After 40 programmed minutes of acquisition and 12 min of maintenance, without notice, both schedules changed to extinction for 28 min.
(6) This differential absorbance is linear with increasing concentrations of Na2MoO4 and was used to calculate the molar extinction coefficient of molybdochelin at 425 nm (epsilon similar to 6,200).
(7) However, during massed testing, all subjects trained with response contingent CS termination showed an overall extinction influence, which was most pronounced in the medial subgroup, although the laterals showed frequency control as well.
(8) When reinforcement for competing behavior was withdrawn, however, rats resumed their original behavior and there were no overall savings in total responses to extinction.
(9) The relative amount of the crystals was measured in both amoeba strains on the basis of the integral extinction value.
(10) Chronic extinction of chain closed conditioned reflex in intact rabbits took five to six days.
(11) The amounts of phosphatidylcholine and sphingomyelin could be determined by high-performance liquid chromatography and ultraviolet absorption if the apparent extinction coefficient of the material analyzed was established.
(12) In a number of neurones the extinction of reflexes either does not change the reaction to acetylcholine, or enhances it.
(13) In Experiment 3, following an unsignaled reinforcement delay, groups receiving either no event or signaled food in the context responded faster in extinction than groups receiving no context exposure or unsignaled food.
(14) The optical extinction decreases as the red cell agglutinates grow, giving a parametric estimate of the haemagglutination rate.
(15) By calculating for DNA standard solutions the value of the ratio between the extinction at 665 nm after 15 min to the extinction of 600 nm after 2 min of the orcinol reaction it is possible to increase specifiaty of the orcinol method for determination of the RNA content.
(16) To lose the Sundarbans would be to move a step closer to the extinction of these majestic animals," said ZSL tiger expert Sarah Christie.
(17) Values obtained for thebuoyant density, isoelectric point, and extinction coefficient differed minimally; major differences were observed in the molecular weight and the characterisitc width of cylinders formed by in vitro-assembled T-layer of the wild-type and variant.
(18) The CS+ preference persisted for several weeks during extinction tests when both the CS+ and CS- were paired with IG water or with no infusions.
(19) The extinction coefficient at 550 nm for the oxidized enzyme is about 5300 (M subunit)-1 X cm-1.
(20) On this planet, extinction is the norm – of the 4 billion species ever thought to have evolved, 99% have become extinct.
Ratite
Definition:
(a.) Of or pertaining to the Ratitae.
(n.) One of the Ratitae.
Example Sentences:
(1) In ducks and ratite birds, lymph heart myocytes more slowly but progressively differentiate a cytomorphology that does not conform in all characteristics to cardiac or skeletal muscle and even resembles in some aspects, smooth muscle.
(2) Although the phylogeny of Ratites is disputed, in particular their possible common origin with Carinates, which include most of the living birds, species of the first sub-class seem to have the same neurohypophysial hormones as those of the second.
(3) We have enzymatically amplified and sequenced approximately 400 base pairs of the mitochondrial 12S rRNA gene from bones and soft tissue remains of four species of moas as well as eight other species of ratite birds and a tinamou.
(4) Two groups of flightless ratite birds existed in New Zealand during the Pleistocene: the kiwis and the moas.
(5) These data support the theory that the ancestors of penguins were flying oceanic birds and that flightlessness in penguins has evolved independently from flightlessness in ratites.
(6) In juvenile ducks and ratites some myocytes differentiate to conductile cells, much as the conductile myocytes and myofibers of the blood heart.
(7) Osteocalcin (the 6,000 dalton Mr gamma-carboxyglutamate-containing protein of bone) has been detected in acid extracts of bones of the extinct class of New Zealand ratite birds, the moas, using a radioimmunoassay for sheep osteocalcin.
(8) This is similar to the pattern shown by ratite birds, where the decline period may be variable and facilitates hatching synchrony.
(9) Ultrastructural investigations of avian cardiac muscle, including ratite hearts, have provided great insights into the mechanisms as to how excitation leads to contraction in the heart.
(10) Alignment of the N-terminal sequence of osteocalcin from the extinct moa against the osteocalcins of the extant ostrich, rhea and emu reveals the homology amongst the ratite species is greater than the homology with the chicken osteocalcin.
(11) Ratites or paleognathid birds may have a different brain-to-metabolism association.
(12) To explain the current geographic distribution of ratites and the magnitude of the transferrin distances, it is supposed that the ancestors of these flightless birds walked across land bridges between the southern continents during Cretaceous times.
(13) These predictions seem to hold well for published data on the development of eggs of fish and ratite, precocial and altricial birds.
(14) Metallic proventricular foreign bodies are a potential source of heavy metal poisoning in ratites.
(15) A biochemical approach was used to study the evolution of ratite birds, i.e., the ostriches, rheas, cassowaries, emus, and kiwis.
(16) Quantitative immunological comparison of transferrin from ratites, tinamous, and other flying birds indicates that all the ratites and tinamous are allied phylogenetically and that they are of monophyletic origin relative to other birds.
(17) Osteocalcin the major gamma carboxyglutamic acid containing protein of vertebrate bone has been purified from the bones of a specimen of Pachyornis elephantopus, a species of the extinct class of New Zealand ratite birds, the moas.
(18) The study of the ratite conduction fibers bears out the idea of an inverse relationship between the size of the gap junctions and the input resistance of cardiac cells.
(19) The geometry of the conduction fibers of ratite hearts confirms earlier observations on birds showing that the geometry of the conduction system and its component cells is adapted to hearts of different sizes and rates of contraction so as to maintain a differential in conduction velocities between the conduction system and the working fibers.
(20) Thus, New Zealand probably was colonized twice by ancestors of ratite birds.