Biomedical subjects

K H James

Publications and source records attributed to K H James.

4 recordsLinked to original sources

PubMed2002

"Active" and "passive" learning of three-dimensional object structure within an immersive virtual reality environment.

We used a fully immersive virtual reality environment to study whether actively interacting with objects would effect subsequent recognition, when compared with passively observing the same objects. We found that when participants learned object structure by actively rotating the objects, the objects were recognized faster during a subsequent recognition task than when object structure was learned through passive observation. We also found that participants focused their study time during active exploration on a limited number of object views, while ignoring other views. Overall, our results suggest that allowing active exploration of an object during initial learning can facilitate recognition of that object, perhaps owing to the control that the participant has over the object views upon which they can focus. The virtual reality environment is ideal for studying such processes, allowing realistic interaction with objects while maintaining experimenter control.

Adult↗

PubMed2001

Manipulating and recognizing virtual objects: where the action is.

In an earlier report (Harman, Humphrey, & Goodale, 1999), we demonstrated that observers who actively rotated three-dimensional novel objects on a computer screen later showed faster visual recognition of these objects than did observers who had passively viewed exactly the same sequence of images of these virtual objects. In Experiment 1 of the present study we showed that compared to passive viewing, active exploration of three-dimensional object structure led to faster performance on a "mental rotation" task involving the studied objects. In addition, we examined how much time observers concentrated on particular views during active exploration. As we found in the previous report, they spent most of their time looking at the "side" and "front" views ("plan" views) of the objects, rather than the three-quarter or intermediate views. This strong preference for the plan views of an object led us to examine the possibility in Experiment 2 that restricting the studied views in active exploration to either the plan views or the intermediate views would result in differential learning. We found that recognition of objects was faster after active exploration limited to plan views than after active exploration of intermediate views. Taken together, these experiments demonstrate (1) that active exploration facilitates learning of the three-dimensional structure of objects, and (2) that the superior performance following active exploration may be a direct result of the opportunity to spend more time on plan views of the object.

Adolescent↗

PubMed1992

Biocompatibility of particulate polymethylmethacrylate bone cements: a comparative study in vitro and in vivo.

The biocompatibility of particles of four different commercial polymethylmethacrylate (PMMA) bone cements was evaluated by exposing human synovial fibroblasts and mouse peritoneal macrophages to particles of cement. Cell integrity and inflammatory potential were assessed using enzyme release and microscopical examination. Results suggested the occurrence of cell damage in both cell types and macrophage studies indicated inflammatory potential. The response in vivo was investigated by intra-articular injection of the particles into mouse knee joints. Clinical and histological evaluation was performed over 2-52 wk. Particles of all four cements were well tolerated in the joints.

Acetylglucosaminidase↗

PubMed1991

Biocompatibility of particles of GORE-TEX cruciate ligament prosthesis: an investigation both in vitro and in vivo.

This research was to determine the biocompatibility of simulated wear particles from a GORE-TEX cruciate ligament prosthesis using in vitro and in vivo techniques. Exposure of normal human synovial fibroblasts and primary mouse peritoneal macrophages to the particles revealed no cytotoxicity, as determined by lactate dehydrogenase release, but beta-N-acetyl-D-glucosaminidase was released from macrophages at high concentrations, showing inflammatory potential. This was not seen when the particles were injected into mouse knees, where no adverse reactions were observed. These simulated wear particles were shown to be biocompatible using these in vitro and in vivo systems.

Acetylglucosaminidase↗