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Biomedical subjects

J G Sample

Publications and source records attributed to J G Sample.

4 recordsLinked to original sources
PubMed2001

Granular drag on a discrete object: shape effects on jamming.

We study the drag force on discrete objects with circular cross section moving slowly through a spherical granular medium. Variations in the geometry of the dragged object change the drag force only by a small fraction relative to shape effects in fluid drag. The drag force depends quadratically on the object's diameter as expected. We do observe, however, a deviation above the expected linear depth dependence, and the magnitude of the deviation is apparently controlled by geometrical factors.

Journal Article↗
PubMed2001

Stick-slip fluctuations in granular drag.

We study fluctuations in the drag force experienced by an object moving through a granular medium. The successive formation and collapse of jammed states give a stick-slip nature to the fluctuations which are periodic at small depths but become "stepped" at large depths, a transition that we interpret as a consequence of the long-range nature of the force chains and the finite size of our experiment. Another important finding is that the mean force and the fluctuations appear to be independent of the properties of the contact surface between the grains and the dragged object. These results imply that the drag force originates in the bulk properties of the granular sample.

Journal Article↗
PubMed1995

Preparatory information for myelogram.

This study identified preparatory information appropriate for patients undergoing myelogram. Twenty-eight patients (16 lumbar and 12 cervical) described the sensations they experienced as they were having a myelogram. Sensations reported by 40% or more of the participants having both kinds of myelograms included hard, cold examining table; wet and cold cleansing of site; stick with injection of local anesthetic; sharp stick with spinal needle insertion; and burning (cervical) or sharp, tingling (lumbar) with contrast medium injection. These sensations, linked with the temporal elements of the procedure, yield a preparatory information intervention appropriate for those scheduled for myelogram. When preparatory information is used for the same myelogram procedure as described in this study, patients should experience reduced anxiety before and during the procedure.

Adult↗