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Focal neurological deficits may be caused by a variety of medical conditions such as head trauma, [1] tumors or stroke; or by various diseases such as meningitis or encephalitis or as a side effect of certain medications such as those used in anesthesia. [2] Neurological soft signs are a group of non-focal neurologic signs. [3]
Focal and diffuse brain injury are ways to classify brain injury: focal injury occurs in a specific location, while diffuse injury occurs over a more widespread area.It is common for both focal and diffuse damage to occur as a result of the same event; many traumatic brain injuries have aspects of both focal and diffuse injury. [1]
In optics, an afocal system (a system without focus) is an optical system that produces no net convergence or divergence of the beam, i.e., has an infinite effective focal length. [1] This type of system can be created with a pair of optical elements where the physical distance d between the elements is equal to the sum of each element's focal ...
A principal focus or focal point is a special focus: For a lens , or a spherical or parabolic mirror , it is a point onto which collimated light parallel to the axis is focused. Since light can pass through a lens in either direction, a lens has two focal points – one on each side.
Cerebral atrophy is a common feature of many of the diseases that affect the brain. [1] Atrophy of any tissue means a decrement in the size of the cell, which can be due to progressive loss of cytoplasmic proteins.
The amoeboid mechanism of invasion has a number of distinctive features. It is characterized by a weak interaction between cells and the surrounding matrix, as well as a lack of or weak focal contacts. The possibility to retain the rapid and non-focal assembly of receptors at the sites of cell contacts with the extracellular substrate exists.
A more typical consumer zoom will have a variable maximum relative aperture since it is harder and more expensive to keep the maximum relative aperture proportional to the focal length at long focal lengths; f /3.5 to f /5.6 is an example of a common variable aperture range in a consumer zoom lens.
Non scarring hair loss, also known as noncicatricial alopecia is the loss of hair without any scarring being present. [1] There is typically little inflammation and irritation, but hair loss is significant. This is in contrast to scarring hair loss during which hair follicles are replaced with scar tissue as a result of inflammation.