phenomenon


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phenomenon

 [fĕ-nom´ĕ-non] (pl. phenom´-�ena)
any sign or objective symptom; any observable occurrence or fact. For names of specific phenomena, see under the name.

phe·nom·e·non

, pl.

phe·nom·e·na

(fĕ-nom'ĕ-non, -nă), Avoid using phenomenon as a plural noun or phenomena as a singular noun.
1. A symptom; an occurrence of any sort, whether ordinary or extraordinary, in relation to a disease.
2. Any unusual fact or occurrence.
[G. phainomenon, fr. phainō, to cause to appear]

phenomenon

/phe·nom·e·non/ (fĕ-nom´ĕ-non) pl. phenom´ena   any sign or objective symptom; an observable occurrence or fact.
booster phenomenon  on a tuberculin test, an initial false-negative result due to a diminished amnestic response, becoming positive on subsequent testing.
dawn phenomenon  the early morning increase in plasma glucose concentration and thus insulin requirement in patients with type 1 diabetes mellitus.
Koebner's phenomenon  a cutaneous response seen in certain dermatoses, manifested by the appearance on uninvolved skin of lesions typical of the skin disease at the site of trauma, on scars, or at points where articles of clothing produce pressure.
Marcus Gunn's pupillary phenomenon  with unilateral optic nerve or retinal disease, a difference between the pupillary reflexes of the two eyes; on the affected side there is abnormally slight contraction or even dilatation of the pupil when a light is shone in the eye.
no-reflow phenomenon  when cerebral blood flow is restored following prolonged global cerebral ischemia, there is initial hyperemia followed by a gradual decline in perfusion until there is almost no blood flow.
Somogyi phenomenon  a rebound phenomenon occurring in diabetes: overtreatment with insulin induces hypoglycemia, thus initiating hormone release; this stimulates lipolysis, gluconeogenesis, and glycogenolysis, which in turn cause rebound hyperglycemia and ketosis.

phenomenon

[finom′ənən] pl. phenomena
Etymology: Gk, phainomenon, something seen
a sign that is often associated with a specific illness or condition and is therefore diagnostically important.

phenomenon

Vox populi An observable fact or event that can be described scientifically. Related terms are Aging phenomenon, Aha! phenomenon, 'Alice in Wonderland,' Alien limb phenomenon, Anesthesia cutoff phenomenon, Anniversary phenomenon, Blowback phenomenon, Booster phenomenon, Clasp-knife phenomenon, Cogwheel phenomenon, Dawn phenomenon, Dragged disc phenomenon, Engel's phenomenon, Flare phenomenon, Fleck phenomenon, Fortification phenomenon, Glass ceiling phenomenon, Harvest moon phenomenon, Hennebert's phenomenon, Herald wave phenomenon, Hunting phenomenon, J curve phenomenon, Jet phenomenon, July phenomenon, Koebner's phenomenon, Mask phenomenon, Mismatch phenomenon, No reflow phenomenon, Nutcracker phenomenon, On-off phenomenon, Pass through phenomenon, R-on-T phenomenon, Ratchet phenomenon, Raynaud's phenomenon, Re-entry phenomenon, Satellite phenomenon, Second disease phenomenon, Second-wind phenomenon, Sticky floor phenomenon, T-on-P phenomenon, Tulio's phenomenon, U curve phenomenon, Uninvolved bystander phenomenon, Vacuum phenomenon, Vanishing cancer phenomenon, Variation phenomenon, Walk-through phenomenon, Waterfall phenomenon, Wavefront phenomenon, West-to-east phenomenon, Will Rogers phenomenon, Zoning phenomenon

phe·nom·e·non

, pl. phenomena (fĕ-nom'ĕ-non, -ă)
1. An occurrence or object as perceived by the senses, whether ordinary or extraordinary, in relation to a disease.
2. Any unusual fact or occurrence.
3. An object of perception; that noticed by mind or senses.
[G. phainomenon, fr. phainō, to cause to appear]

phenomenon 

1. A remarkable event or appearance. 2. A fact or an occurrence that can be described or explained. Plural: phenomena.
Abney's phenomenon A slight change in hue resulting from a change in saturation. This is especially noticeable when white light is added to a monochromatic blue or green light.
Aubert's phenomenon If, in the dark the head is tilted slowly to one side while looking at a bright vertical line, this line will appear to tilt in the opposite direction. This phenomenon is due to the absence of compensatory postural changes. Syn. Aubert's effect.
Aubert-Förster phenomenon When targets (e.g. letters) of different sizes are placed peripheral to the foveal region and at different distances from the observer, visual acuity is better for the smaller targets nearer the observer than for the larger targets farther than the observer, although they subtend the same visual angle. Syn. Aubert-Förster law.
Bell's phenomenon An outward and upward rolling of the eyes when closing, or attempting to close the eyelids. See Bell's sign.
Bezold-Brücke phenomenon A change in perceived hue of some spectral colours with a change in intensity. However, some wavelengths, such as 478, 503 and 578 nm, remain a constant hue with varying intensity. These are called invariant wavelengths or unique hues. Syn. Bezold-Brücke effect.
Bielschowsky's phenomenon In alternating hypertropia, occluding one eye leads to its rotation upward, and then placing a neutral density filter in front of the other eye gives rise to a downward movement of the occluded eye. See Bielschowsky's phenomenon test.
Broca-Sulzer phenomenon See Broca- Sulzer effect.
Brücke-Bartley phenomenon See Brücke- Bartley effect.
crowding phenomenon A difficulty or inability to discriminate small visual acuity tests when they are presented next to each other in a row, thus inducing contour interaction, whereas the same sized acuity symbols presented singly against a uniform background are resolved. Although this phenomenon may be experienced by normal patients, it is most often characteristic of amblyopic eyes and of people with reading difficulties. Syn. crowding effect. See morphoscopic visual acuity; amblyopia.
doll's head phenomenon Reflex movement of the eyes in a direction opposite to the direction of a rapid head turn, followed by a return towards the original position. These vestibular-elicited eye movements are aimed at maintaining fixation. The phenomenon can be used to assess the integrity of the vestibulo-ocular response system (doll's head test). If the eye movements do not accord with the above, it may indicate a brainstem defect. Syn. doll's eye sign.
entoptic phenomenon See entoptic image.
extinction phenomenon A condition in which individual stimuli placed in the visual field are seen, but when the nasal field of one eye and the temporal field of the other eye are stimulated simultaneously the subject fails to see one of the stimuli. This condition is common following a stroke. Syn. pseudo-hemianopia. See visual neglect.
Fick's phenomenon See Sattler's veil.
jack-in-the-box phenomenon When wearing very high positive lenses (e.g. in aphakia) there exists an area in the periphery situated between the outer extent of the field seen through the lens and the field beyond the edge of the lens, which is not seen (ring scotoma). This phenomenon refers to the disappearance and sudden reappearance of an object when the eye moves from the periphery to the centre passing over the ring scotoma. This phenomenon can be avoided by turning the head rather than the eye for peripheral viewing or by correcting with contact lenses. Modern aspheric lenses minimize this phenomenon as they have reduced peripheral power. See real field of view; ring scotoma.
jaw-winking phenomenon An abnormal condition associated with congenital ptosis, characterized by the elevation of the ptotic eyelid when the mouth is opened or the jaw is moved laterally to the side opposite to the ptosis. The eyelid droops again if the jaw maintains its new position or is closed. The condition often diminishes with time, otherwise surgery is the main treatment. Syn. Marcus Gunn phenomenon; Marcus Gunn jaw-winking syndrome.
Marcus Gunn phenomenon See jaw-winking phenomenon.
Mizuo's phenomenon The appearance of a golden brown colour of the retina as it adapts to light, in Oguchi's disease. When adapted to darkness the fundus has the normal red appearance. Syn. Mizuo's sign.
phi phenomenon See phi movement.
Pulfrich phenomenon See Pulfrich stereophenomenon.
Purkinje's phenomenon See Purkinje shift.
Riddoch phenomenon Ability to perceive the motion of an object while being unable to detect any other features of that object, such as its colour or its form. This may occur in a scotomatous area of the visual field caused by a lesion somewhere in the visual pathway from the lateral geniculate body to the occipital and temporal cortex.
Troxler's phenomenon An image in the periphery of the retina tends to fade or disappear during steady fixation of another object. This phenomenon is rarely noticed due to the involuntary eye movements. When these are neutralized optically, as in stabilized retinal imagery, the phenomenon occurs readily even in central vision. See fixation movements; stabilized retinal image.
Uhthoff's phenomenon See Uhthoff's symptom.

phe·nom·e·non

, pl. phenomena (fĕ-nom'ĕ-non, -ă)
A symptom; an occurrence of any sort, whether ordinary or extraordinary, in relation to a disease.
[G. phainomenon, fr. phainō, to cause to appear]

phenomenon

pl. phenomena [Gr.] any observable occurrence or fact of which the cause is not immediately evident. In veterinary science usually relates to laboratory findings but can relate to clinical signs. Typical examples are berry-dedrick phenomenon, camp phenomenon, koch phenomenon, rickettsial interference phenomenon, satellitism, swarming (1).

first-set reaction, phenomenon

rejection of a first allograft is slow, taking about 10 days, in contrast to a second-set reaction. See also rejection.

second-set reaction, phenomenon

References in classic literature ?
The same phenomenon is said to occur occasionally in the adjacent province of Guayra, where stones of the bigness of a man's hand are exploded, with a loud noise, from the bosom of the earth, and scatter about glittering and beautiful fragments that look like precious gems, but are of no value.
In whatever way this singular phenomenon may be accounted for, the existence of it appears to be well established.
But the mind of man not only refuses to believe this explanation, but plainly says that this method of explanation is fallacious, because in it a weaker phenomenon is taken as the cause of a stronger.
But she had been kept up late every night, and put upon an unlimited allowance of gin-and-water from infancy, to prevent her growing tall, and perhaps this system of training had produced in the infant phenomenon these additional phenomena.
Making himself very amiable to the infant phenomenon, was an inebriated elderly gentleman in the last depths of shabbiness, who played the calm and virtuous old men; and paying especial court to Mrs Crummles was another elderly gentleman, a shade more respectable, who played the irascible old men--those funny fellows who have nephews in the army and perpetually run about with thick sticks to compel them to marry heiresses.
As to the phenomenon known as the "ashy light," it is explained naturally by the effect of the transmission of the solar rays from the earth to the moon, which give the appearance of completeness to the lunar disc, while it presents itself under the crescent form during its first and last phases.
Just so," continued Barbicane; "and when it has passed the point of equal attraction, its base, being the heavier, will draw it perpendicularly to the moon; but, in order that this phenomenon should take place, we must have passed the neutral line.
Yes, the moon, on whose surface objects weigh six times less than on the earth, a phenomenon easy to prove.
This phenomenon is more exhilarating to me than the luxuriance and fertility of vineyards.
Yes, during that famous night when the strange phenomenon occurred.
Every psychical phenomenon is characterized by what the scholastics of the Middle Ages called the intentional (also the mental) inexistence of an object, and what we, although with not quite unambiguous expressions, would call relation to a content, direction towards an object (which is not here to be understood as a reality), or immanent objectivity.
When electricity was discovered," Levin interrupted hurriedly, "it was only the phenomenon that was discovered, and it was unknown from what it proceeded and what were its effects, and ages passed before its applications were conceived.