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W J Heiser

Publications and source records attributed to W J Heiser.

11 recordsLinked to original sources
PubMed2000

Triadic distance models for the analysis of asymmetric three-way proximity data.

Triadic distance models can be used to analyse proximity data defined on triples of objects. Three-way symmetry is a common assumption for triadic distance models. In the present study three-way symmetry is not assumed. Triadic distance models are presented for the analysis of asymmetric three-way proximity data that result in a simultaneous representation of symmetry and asymmetry in a low-dimensional configuration. An iterative majorization algorithm is developed for obtaining the coordinates and the representation of the asymmetry. The models are illustrated by an example using longitudinal categorical data.

Algorithms↗
PubMed1980

Common calcaneal avulsion fracture.

An avulsion fracture on the dorsolateral aspect of the calcaneus at the origin of the extensor digitorum brevis muscle was identified after inversion injuries of the ankle. The avulsion occurred in 10% of emergency room patients with clinically suspected ankle fractures. The routine dorsoplantar view of the foot and/or the routine anteroposterior view of the ankle demonstrated the fracture. The fracture is most often confused with the os peroneum, or with the fracture of the anterior process of the calcaneus. Treatment is conservative with elevation, supportive bandage, and early activity.

Adolescent↗
PubMed1978

Right subhepatic abscesses detected by technetium liver scans.

A focal defect at the inferior margin of the right lobe of the liver was found in two patients with subhepatic abscesses. This defect must be differentiated from the porta hepatis and the gallbladder fossa. When technetium liver scans are obtained in patients with usspect abdominal abscesses, the inferior margin of the right lobe of the liver should be carefully scrutinized so that right subhepatic abscesses will not be overlooked.

Abdomen↗
PubMed1978

Schistosomiasis of the spinal cord.

Schistosomiasis of the spinal cord is a rare presentation of a disease involving over 200 million people. A patient from an endemic area presenting as a transverse myelitis or a spinal cord tumor, and with eosinophilia, should alert the physician to the possibility of schistosomiasis of the spinal cord. Diagnosis is based on finding the characteristic eggs in the stool or urine, or if necessary, by rectal, bladder or liver biopsies. Myelography is performed to determine if decompressive laminectomy is necessary.

Adult↗
PubMedDate not supplied

Brain iron in patients with Parkinson disease: MR visualization using gradient modification.

In patients with Parkinson disease, improved visualization of brain iron on a mid-field-strength magnet can be obtained with T2-weighted images and elimination of phase-encoding artifacts. A long echo delay time accentuates the loss of signal from brain iron. However, the long pulse sequence creates phase-encoding artifacts from CSF pulsations at the level of the basal ganglia. These artifacts are eliminated and resolving power increased with additional pulsing in the slice-selective and read gradients. Elimination of motion artifacts enhances visualization of brain iron in three ways: (1) extrapyramidal nuclei containing iron have better definition, (2) abnormalities are better identified, and (3) pseudolesions disappear. Our findings suggest there is significant improvement in the resolving power of brain iron on MR scans made with a mid-field-strength scanner when gradient modification is used.

Adult↗