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Biomedical subjects

R A Carver

Publications and source records attributed to R A Carver.

12 recordsLinked to original sources
PubMed1997

Effects of amount of attention allocated to the location of visual stimulus pairs on perception of simultaneity.

This study was examined whether a change in the amount of attention equally allocated to two locations affects judgments of the simultaneity or successiveness of stimuli presented at those locations. Observers were cued to expect two brief flashes either to the left and right of fixation or above and below fixation. Stimulus onset asynchrony was randomly varied. On a small proportion of trials, the stimuli appeared at the unexpected locations. Observers were more likely to report the stimuli as simultaneous when they appeared in the unexpected locations. A model proposed to account for the data assumes that a brief stimulus event is represented by a probability distribution reflecting the uncertainty in determining the time of the event's occurrence, and two events are judged to be simultaneous if they are perceived to fall within some critical temporal interval, c, which is a function of the amount of attention allocated to the task.

Adult↗
PubMed1988

What happens to the pylorus after pyloromyotomy?

The rate of return to normal of the pylorus muscle in infantile hypertrophic pyloric stenosis was measured by ultrasound, using a simple pyloric volume calculation and a pyloric muscle index. The muscle hypertrophy took from two to 12 weeks to resolve.

Follow-Up Studies↗
PubMed1987

Infantile hypertrophic pyloric stenosis--diagnosis from the pyloric muscle index.

Measurements of pyloric length, diameter and muscle thickness were made from ultrasound images of 39 babies, 21 of whom were subsequently found at operation to have infantile hypertrophic pyloric stenosis. From these measurements, the volume of pyloric muscle in cm3 was estimated for each case and divided by the body weight in kilograms. The resulting pyloric muscle index proved to be a much more reliable guide to the diagnosis of pyloric stenosis than any of the individual measurements or the volume estimation alone.

Humans↗
PubMed1985

Soft-tissue changes accompanying recent scaphoid injuries.

In 200 consecutive cases of suspected scaphoid fracture, 27 such fractures were demonstrated. Radiologically, when a fracture was present, the soft tissues on the dorsum of the wrist were definitely abnormal in 24 cases and equivocal in only three cases, whereas the scaphoid fat pad was normal in two cases and equivocal in 13 cases. In addition, in 88 cases when the soft tissues on the dorsum of the wrist were definitely normal, no fracture was ever demonstrated.

Adipose Tissue↗
PubMed1978

Gas-liquid chromatographic determination of kepone residues in finfish, shellfish, and crustaceans.

Finfish, shellfish, and crustacean samples are extracted with isopropanol and benzene; the extract is filtered and then concentrated. The extract, dissolved in hexane, is treated with oleum and extracted with aqueous alkali. The aqueous phase is acidified and extracted with petroleum ether-ethyl ether (1 + 1). The Kepone residue is determined by electron capture gas-liquid chromatography (GLC). Recoveries obtained by 8 laboratories from 15 species of finfish fortified at 0.02-0.23 ppm ranged from 37 to 107% with a mean +/- relative standard deviation of 79.4 +/- 14.5%. For oysters fortified at 0.01-0.10 ppm, recoveries range from 63 to 129% with a mean of 78.8 +/- 20.8%. For crustaceans fortified at 0.05-0.26 ppm, recoveries ranged from 52 to 110% with a mean of 78 +/- 16.4%. The approximate limits of quantitation for finfish and for shellfish and crustaceans are 0.02 and 0.05 ppm, respectively, under the GLC conditions used in this study.

Animals↗
PubMedDate not supplied

Measurement of tibial torsion by ultrasound.

A method of measuring tibial torsion with ultrasound, using reference lines on the tibia, was developed and tested on dry adult tibiae. This technique was used for evaluation of a group of children with apparently normal tibiae and another group of children with spina bifida, cerebral palsy, or clubfoot. The study showed that it is possible to measure true tibial torsion (rather than tibiofibular torsion) with ultrasound. The technique was found to be reliable and accurate enough for routine clinical use and had advantages over clinical methods and other radiographic imaging techniques. Values obtained by this technique are higher than those obtained by methods using the bimalleolar axis as the distal reference line.

Adult↗