Biomedical subjects

D Winningham

Publications and source records attributed to D Winningham.

3 recordsLinked to original sources

PubMed2006

Plasma acceleration above martian magnetic anomalies.

Auroras are caused by accelerated charged particles precipitating along magnetic field lines into a planetary atmosphere, the auroral brightness being roughly proportional to the precipitating particle energy flux. The Analyzer of Space Plasma and Energetic Atoms experiment on the Mars Express spacecraft has made a detailed study of acceleration processes on the nightside of Mars. We observed accelerated electrons and ions in the deep nightside high-altitude region of Mars that map geographically to interface/cleft regions associated with martian crustal magnetization regions. By integrating electron and ion acceleration energy down to the upper atmosphere, we saw energy fluxes in the range of 1 to 50 milliwatts per square meter per second. These conditions are similar to those producing bright discrete auroras above Earth. Discrete auroras at Mars are therefore expected to be associated with plasma acceleration in diverging magnetic flux tubes above crustal magnetization regions, the auroras being distributed geographically in a complex pattern by the many multipole magnetic field lines extending into space.

Journal Article↗

PubMed2004

Solar wind-induced atmospheric erosion at Mars: first results from ASPERA-3 on Mars Express.

The Analyzer of Space Plasma and Energetic Atoms (ASPERA) on board the Mars Express spacecraft found that solar wind plasma and accelerated ionospheric ions may be observed all the way down to the Mars Express pericenter of 270 kilometers above the dayside planetary surface. This is very deep in the ionosphere, implying direct exposure of the martian topside atmosphere to solar wind plasma forcing. The low-altitude penetration of solar wind plasma and the energization of ionospheric plasma may be due to solar wind irregularities or perturbations, to magnetic anomalies at Mars, or both.

Journal Article↗

PubMed1987

Interface pressures in above-knee sockets.

The interface pressures in above-knee sockets of amputee patients were measured during the stance phase of the gait cycle. The pressures were monitored with a pneumatic sensor array that covered the inside of the socket. A pressure map of the socket surface was developed. This map has been related to the fit of the prosthetic socket. The pressures generated by the quadrilateral socket and the Normal Shape Normal Alignment (NSNA) socket were compared. Significant variations were noted in pressure distribution between the two sockets, but the magnitudes of the pressures in well-fitting sockets of both types were similar. Thus, magnitude of pressure in an above-knee socket may provide a more useful guide than distribution for predicting the fit of an appliance.

Artificial Limbs↗