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Biomedical subjects

R R Walker

Publications and source records attributed to R R Walker.

6 recordsLinked to original sources
PubMed2000

Unilateral mandible fracture with bilateral TMJ dislocation.

Temporomandibular joint (TMJ) dislocation occurs when the condylar head slips forward causing the posterior articulating surface of the condyle to advance ahead of the articular eminence, possibly becoming entrapped. Following dislocation, the ligaments around the joint often stretch, causing severe muscle spasms and joint pain. There is no standard evaluation and treatment method for acute TMJ dislocation, but the most effective course is immediate reduction. This paper presents a 42-year-old woman who sustained a unilateral mandible fracture with bilateral TMJ dislocation in an automobile crash. Although the fracture was apparent on plane film and panorex, the dislocation was not found until six weeks later, when the jaw was unwired. At that time, the dislocation was suspected because of decreased range of motion, but was not verified until an MRI was performed. The result was long-term therapy, eventual bilateral TMJ surgery, and chronic TMJ pain for the patient.

Accidents, Traffic↗
PubMed1995

Choice of soft pulse shapes for signal excitation in chemical shift selective imaging.

The choice of soft pulse shapes for chemical shift selective excitation in chemical shift imaging is discussed. In the presence of inhomogeneities in the static magnetic field resulting from susceptibility anomalies, it is important to optimise pulse bandshape and frequency offset as well as bandwidth, in order to minimize artefacts arising from excitation of unwanted resonances. A comparison of the use of Gaussian and sinc shaped excitation pulses in the chemical shift micro-imaging of grapes serves to illustrate some of the effects that may be observed.

Magnetic Resonance Spectroscopy↗
PubMed1992

Artifacts in chemical shift selective imaging.

The role of susceptibility effects in the production of artifacts in chemical shift images generated by the selective excitation technique is discussed. The effects are demonstrated in images of phantom samples of agarose gels containing small air bubbles. The artifacts can lead to erroneous interpretations, in which the resonances to be resolved exhibit a relatively small chemical shift separation, such as that between water and soluble carbohydrates (sugars).

Artifacts↗
PubMed1991

The Multidimensional Scale of Perceived Social Support: a confirmation study.

This study examined the psychometric properties of the Multidimensional Scale of Perceived Social Support (MSPSS; Zimet, Dahlem, Zimet, & Farley, 1988) with a diverse group of 154 students at an urban college. The following areas were investigated: internal reliability, factorial validity, social desirability bias, and the moderating effect of social support between stressful life events and depression (i.e., the buffering hypothesis). The MSPSS had good internal reliability, and the factor analysis confirmed the subscale structure of the measure: family, friends, and significant other. There was no indication that social desirability bias influenced subjects' responses. Finally, social support was related to depression only for those subjects who were experiencing high levels of life stress, which lends support for the buffering hypothesis.

Attitude↗