(n.) The act of extinguishing or making extinct; a putting an end to; the act of putting out or destroying light, fire, life, activity, influence, etc.
(n.) State of being extinguished or of ceasing to be; destruction; suppression; as, the extinction of life, of a family, of a quarrel, of claim.
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(8) When reinforcement for competing behavior was withdrawn, however, rats resumed their original behavior and there were no overall savings in total responses to extinction.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.
Pleistocene
Definition:
(a.) Of or pertaining to the epoch, or the deposits, following the Tertiary, and immediately preceding man.
(n.) The Pleistocene epoch, or deposits.
Example Sentences:
(1) Amino acid analyses have been made of the insoluble protein, soluble peptide, and free amino acid fractions isolated from a series of fossil pecten shells of ages from the Pleistocene through the Jurassic.
(2) Genetic data on present human population relationships and data from the Pleistocene fossil hominid record are used to compare two contrasting models for the origin of modern humans.
(3) The present study on 47 naturally fractured enamel surfaces of premolar and molar teeth of Plio-Pleistocene East African hominids measured enamel thickness, slope of incremental lines (striae of Retzius), and the morphology of Hunter Schreger bands (HSBs).
(4) The subocclusal morphology of 168 permanent mandibular premolars (N = 77) and molars (N = 91) of Plio-Pleistocene hominids has been investigated.
(5) The morphological comparison shows strong affinities to comparative material from the Upper Pleistocene like Cro-Magnon.
(6) The cultural associations in the earlier late Pleistocene are with the Middle Stone Age.
(7) The latest fossil is the only intact skull ever found of a human ancestor that lived in the early Pleistocene, when our predecessors first walked out of Africa.
(8) The diets of these Plio-Pleistocene hominids appear to have been qualitatively dissimilar.
(9) The concentration of climate-warming carbon dioxide is now higher than at any time since the dawn of humans 2.6m years ago, an event itself marked by a new geological epoch called the Pleistocene.
(10) The morphology of the nasal bones and their articulations with the adjoining frontal and maxillary bones have recently been reported in Nature and elsewhere to be diagnostic of hominoid taxa, and cladistic analysis based on these features has been used to assign two immature Plio-Pleistocene hominoids (AL 333-105 and Taung) to different lineages (Paranthropus and Homo, respectively).
(11) Pilbeam and Gould have discussed African Plio-Pleistocene hominid evolution in the context of allometry (size-dependent morphological change).
(12) The antiquity of the lesion is demonstrated by its appearance among late Pleistocene human remains.
(13) glabrata (Say, 1818) from upper Pleistocene (or Holocene) based on paleontologic and stratigraphic data and in agreement with shell morphology.
(14) The dwarfing of large mammals on islands occurred repeatedly in the Pleistocene.
(15) The coefficient of variation of ECV that characterizes a group composed of all Plio-Pleistocene gracile hominids does not support a single polytypic species interpretation of this assemblage.
(16) Extinctions occurred throughout the European Pleistocene, but until the late Pleistocene most losses were replaced by the evolution or immigration of new species, and most of those lost without replacement were small mammals.
(17) Fragmented mandibles of two Pleistocene lions (Panthera leo atrox) recovered from Yukon Territory possessed acquired pathological changes and congenital abnormalities, judging from the anatomy of contemporary and modern lions.
(18) Associated fore- and hindlimb parts of five individuals are known from the hominid Plio-Pleistocene fossil collections in Africa.
(19) The ancient Pleistocene call of the moon, of salt in the blood, and genetic encoding buried deep in the chromosomes back there beneath the layers of culture – and counterculture – are making successful businesswomen, professionals and even the mothers of grown children stop and reconsider.” The metaphor of the biological clock sounded less florid than the metaphors that followed, but it evinced the same determinism.
(20) The former model infers multiple regional archaic-modern connections and the ancient establishment of regional characteristics, whereas the latter model implies only an African archaic-all modern relationship, with recent (late Pleistocene) development of regionality.