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Focal length
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Focal length Relates the distance between an image source and a lens and the distance of the lens to the image by the lenses focal length.
RELATED TERMS--------------------------------------
Lens
The lens of the eye is like an adjustable lens of a camera and focuses light rays on to the retina for sharp images. A condition called presbyopia occurs when the lens is no longer able to adjust for objects at different distances.
Focal
Limited to one specific area.
SIMILAR TERMS--------------------------------------
Focal
Limited to one specific area.
Focal dystonia due to blepharospasm
The involuntary forcible closure of the eyelid due to spasms. The first symptoms may be uncontrollable blinking. Only one eye may be affected initially, but eventually both eyes are usually involved. The spasms may leave the eyelids completely closed causing functional blindness even though the eyes beneath the lids and vision are normal. Following torticollis (spasm of the neck muscles), blepharospasm is the next most common form of focal dystonia. For more information about dystonias, see: Dystonia.
Focal dystonia due to torticollis
Spasm of the muscles in the neck that control the position of the head, causing the head to twist and turn to one side. In addition, the head may be pulled forward or backward. Torticollis is the most common form of focal dystonia.
Focal gigantism
1. The excessive growth of a specific body part such as a hand or foot, as with increased blood supply to that part. 2. The excessive growth of a combination of particular body parts, as is characteristic of a congenital malformation syndrome called the Wiedemann-Beckwith syndrome. Focal gigantism may occur before or after the bones fuse. If it occurs afterwards, it causes disfigurement, as in acromegaly. Surgery for mass reduction may sometimes improve function.
Focal motor seizure
A simple partial seizure with localized motor activity. There may be spasm or clonus (jerking) of one muscle or a muscle group and this may remain localized or it may subsequently spread to adjacent muscles as a Jacksonian seizure.
Focal vision
The role of vision involved in the examination and identification of objects associated with the fovea and exploratory eye movements.
Focalin
Integral part of total treatment program to stabilize ADHD/ADD.
Focalin xr
Focalin xr is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): dexmethylphenidate hydrochloride.
PREVIOUS AND NEXT TERMS--------------------------------------
First-Order motion mechanisms
Captures motion information from moving objects or features that differ from the background in luminance.
Fixation
Alignment of the eyes so that the image of the fixated target falls on the area centralis. For animals with immobile eyes the alignment of the head towards the fixated target.
Flicker
Alternating levels of brightness.
Flicker photometry experiment
Stimuli consisting of a pair of different color test lights alternate. When the lights alternate slowly the pattern appears to change between the colors of the two lights. When the lights alternate rapidly observers fail to see the color modulation and instead perceive a dark-light modulation. Demonstrates that the temporal resolution for distinguishing blue-yellow is less than red-green which in turn is less than light-dark.
Floater
A blurry spot that appears to float around in the eye but does not block vision. The blur is the result of debris from the vitreous humour casting a shadow on the retina.
Focal length
Focal vision
The role of vision involved in the examination and identification of objects associated with the fovea and exploratory eye movements.
Foveola
The center of the fovea.
Full-Wave rectification
A signal which shows a positive response to both the positive and negative parts of a sinusiod (i.e. frequency doubling). Many complex cells show this to contrast reversing patterns.
Fibrin
A filamentous protein formed from the precursor fibrinogen by the enzyme thrombin.
Flocculent
Having downy or flaky shreds.
RELATED TERMS--------------------------------------
Lens
The lens of the eye is like an adjustable lens of a camera and focuses light rays on to the retina for sharp images. A condition called presbyopia occurs when the lens is no longer able to adjust for objects at different distances.
Focal
Limited to one specific area.
SIMILAR TERMS--------------------------------------
Focal
Limited to one specific area.
Focal dystonia due to blepharospasm
The involuntary forcible closure of the eyelid due to spasms. The first symptoms may be uncontrollable blinking. Only one eye may be affected initially, but eventually both eyes are usually involved. The spasms may leave the eyelids completely closed causing functional blindness even though the eyes beneath the lids and vision are normal. Following torticollis (spasm of the neck muscles), blepharospasm is the next most common form of focal dystonia. For more information about dystonias, see: Dystonia.
Focal dystonia due to torticollis
Spasm of the muscles in the neck that control the position of the head, causing the head to twist and turn to one side. In addition, the head may be pulled forward or backward. Torticollis is the most common form of focal dystonia.
Focal gigantism
1. The excessive growth of a specific body part such as a hand or foot, as with increased blood supply to that part. 2. The excessive growth of a combination of particular body parts, as is characteristic of a congenital malformation syndrome called the Wiedemann-Beckwith syndrome. Focal gigantism may occur before or after the bones fuse. If it occurs afterwards, it causes disfigurement, as in acromegaly. Surgery for mass reduction may sometimes improve function.
Focal motor seizure
A simple partial seizure with localized motor activity. There may be spasm or clonus (jerking) of one muscle or a muscle group and this may remain localized or it may subsequently spread to adjacent muscles as a Jacksonian seizure.
Focal vision
The role of vision involved in the examination and identification of objects associated with the fovea and exploratory eye movements.
Focalin
Integral part of total treatment program to stabilize ADHD/ADD.
Focalin xr
Focalin xr is a prescription or over-the-counter drug which is (or once was) approved in the United States and possibly in other countries. Active ingredient(s): dexmethylphenidate hydrochloride.
PREVIOUS AND NEXT TERMS--------------------------------------
First-Order motion mechanisms
Captures motion information from moving objects or features that differ from the background in luminance.
Fixation
Alignment of the eyes so that the image of the fixated target falls on the area centralis. For animals with immobile eyes the alignment of the head towards the fixated target.
Flicker
Alternating levels of brightness.
Flicker photometry experiment
Stimuli consisting of a pair of different color test lights alternate. When the lights alternate slowly the pattern appears to change between the colors of the two lights. When the lights alternate rapidly observers fail to see the color modulation and instead perceive a dark-light modulation. Demonstrates that the temporal resolution for distinguishing blue-yellow is less than red-green which in turn is less than light-dark.
Floater
A blurry spot that appears to float around in the eye but does not block vision. The blur is the result of debris from the vitreous humour casting a shadow on the retina.
Focal length
Focal vision
The role of vision involved in the examination and identification of objects associated with the fovea and exploratory eye movements.
Foveola
The center of the fovea.
Full-Wave rectification
A signal which shows a positive response to both the positive and negative parts of a sinusiod (i.e. frequency doubling). Many complex cells show this to contrast reversing patterns.
Fibrin
A filamentous protein formed from the precursor fibrinogen by the enzyme thrombin.
Flocculent
Having downy or flaky shreds.
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This dictionary contains 19186 terms.
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