Items tagged “definition”
93 results found
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Off-ended
The term off-ended is used by some orthopedic surgeons and radiologists to describe a long bone fracture that is displaced by more than the width of the bone. An off-ended fracture is often shortened due to muscle contraction.
Article
Amputation (generic)
The term amputation refers to the disconnection of all or part of a limb from the body. Specifically, amputation is defined as the removal of the structure through a bone. This is in contrast to disarticulation, which is the removal of the structure through a joint.
When due to trauma, traumati...
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Efface
Efface is a term frequently used by radiologists, most often in the context of CSF-containing spaces in the brain (sulci and ventricles). Unfortunately, it is often used incorrectly.
The word efface, in general English usage, means to cause something to fade or disappear 1,2.
In the context o...
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Retropulsed fragment
A retropulsed fragment is any vertebral fracture fragment that is displaced into the spinal canal, thereby potentially causing spinal cord injury.
They usually arise from the vertebral body with or without a portion of the pedicle, and are displaced posteriorly, hence the prefix 'retro'.
Article
Butterfly fragment (fracture)
Butterfly fragments are large, triangular fracture fragments seen commonly in comminuted long bone fractures. The term is commonly used in orthopedic surgery, and results from two oblique fracture lines meeting to create a large triangular or wedge-shaped fragment located between the proximal an...
Article
Batch size (machine learning)
Batch size is a term used in machine learning and refers to the number of training examples utilized in one iteration. The batch size can be one of three options:
batch mode: where the batch size is equal to the total dataset thus making the iteration and epoch values equivalent
mini-batch mod...
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Epoch (machine learning)
An epoch is a term used in machine learning and indicates the number of passes of the entire training dataset the machine learning algorithm has completed. Datasets are usually grouped into batches (especially when the amount of data is very large). Some people use the term iteration loosely and...
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Iteration (machine learning)
An iteration is a term used in machine learning and indicates the number of times the algorithm's parameters are updated. Exactly what this means will be context dependent. A typical example of a single iteration of training of a neural network would include the following steps:
processing the ...
Article
Cost function (machine learning)
A cost function is a mechanism utilized in supervised machine learning, the cost function returns the error between predicted outcomes compared with the actual outcomes. The aim of supervised machine learning is to minimize the overall cost, thus optimizing the correlation of the model to the sy...
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Backpropagation (machine learning)
Backpropagation in supervised machine learning is the process used to calculate the gradient of the error function associated with each parameter weighting within a convoluted neural network (CNN). Essentially, the gradient estimates how the system parameters should change in order to optimize t...
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Otorrhagia
Otorrhagia denotes hemorrhage from the external acoustic meatus and is commonly seen in the setting of petrous temporal bone fractures or soft tissue injuries to the external or middle ear. Rarely an internal carotid artery aneurysm with dehiscence into the middle ear can present with spontaneou...
Article
Lagophthalmos
Lagophthalmos refers to the inability of an individual to completely close the eyelids and can result in drying of the eyes and irritation, and even permanent damage.
Pathology
Etiology
most common in facial nerve palsies (e.g. Bell palsy)
Ramsay Hunt syndrome 4
trauma/surgery: scarring of...
Article
Skiagraphy
Skiagraphy (rarely sciagraphy) is an archaic term for taking a radiograph and this usage (see below) appears to have first been proposed by Sydney Rowland in 1896 1. Skiagrapher was the term used for a radiographer until the end of the First World War. In the early days, a skiagram, (or skiagrap...
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Pyrexia of unknown origin
A pyrexia of unknown origin, commonly shortened to PUO, and also known as a fever of unknown origin (FUO), was originally defined in 1961 as the condition in which the core body temperature is >38.3oC for a period of three weeks or more, with no diagnosis reached after one week of inpatient inve...
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Spondyloptosis
Spondyloptosis is a term to denote grade V spondylolisthesis - a vertebra having slipped so far with respect to the vertebra below that the two endplates are no longer congruent. It is usually anterolisthesis of L5 on S1 but can be seen elsewhere rarely 1,2.
Article
Anlage
An anlage in biology refers to the primordial precursor of a tissue or organ, which is still recognisable as a collection of cells that will form that specific tissue.
The term is commonly used in medicine to refer to organs, such as the pancreas, when one is describing anatomical variants and ...
Article
Cerebellar tonsillar ectopia
Cerebellar tonsillar ectopia denotes an inferior location of the cerebellar tonsils below the margins of the foramen magnum. It, therefore, encompasses both minor asymptomatic tonsilar ectopia and Chiari I malformations.
Terminology
Use of the term cerebellar tonsillar ectopia is not uniform....
Article
Acquired tonsillar ectopia
Acquired tonsillar ectopia is usually thought of as a subgroup of cerebellar tonsillar ectopia in which downward displacement of the cerebellar tonsils is secondary to another well defined and distinct pathological process. This is to distinguish it from Chiari I malformations and low-lying tons...
Article
Low-lying tonsils
Low-lying tonsils, sometimes also called benign tonsillar ectopia, is a subtype of cerebellar tonsillar ectopia denoting asymptomatic and only slight downward descent of the cerebellar tonsils through the foramen magnum and is distinct from Chiari I malformations. Typically a descent of less tha...
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Sphenoidal ridge
The sphenoidal ridge, or sphenoid ridge, is the sharp curving bony edge at the posterior aspect of the lesser wing of the sphenoid bone. It separates the horizontal floor of the anterior cranial fossa in front from the vertical anterior wall of the middle cranial fossa behind 1.
Related patholo...
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