Biomedical subjects

Xiaodong Song

Publications and source records attributed to Xiaodong Song.

3 recordsLinked to original sources

PubMed2006

Evidence for a chemical-thermal structure at base of mantle from sharp lateral P-wave variations beneath Central America.

Compressional waves that sample the lowermost mantle west of Central America show a rapid change in travel times of up to 4 s over a sampling distance of 300 km and a change in waveforms. The differential travel times of the PKP waves (which traverse Earth's core) correlate remarkably well with predictions for S-wave tomography. Our modeling suggests a sharp transition in the lowermost mantle from a broad slow region to a broad fast region with a narrow zone of slowest anomaly next to the boundary beneath the Cocos Plate and the Caribbean Plate. The structure may be the result of ponding of ancient subducted Farallon slabs situated near the edge of a thermal and chemical upwelling.

Journal Article↗

PubMed2005

Inner core differential motion confirmed by earthquake waveform doublets.

We analyzed 18 high-quality waveform doublets with time separations of up to 35 years in the South Sandwich Islands region, for which the seismic signals have traversed the inner core as PKP(DF). The doublets show a consistent temporal change of travel times at up to 58 stations in and near Alaska, and they show a dissimilarity of PKP(DF) coda. Using waveform doublets avoids artifacts of earthquake mislocations and contamination from small-scale heterogeneities. Our results confirm that Earth's inner core is rotating faster than the mantle and crust at about 0.3 degrees to 0.5 degrees per year.

Journal Article↗

PubMed2005

PDGF-D contributes to neointimal hyperplasia in rat model of vessel injury.

In this study, we determined the role of PDGF-D, a new member of the PDGF family, in a rat model of balloon injured artery made with a 2F catheter in Sprague-Dawley male rats. PDGF-D expression was studied in the injured and control segments of abdominal aorta. The function of PDGF-D was evaluated in rat vascular smooth muscle cells stably transfected with PDGF-D gene. We found that in normal abdominal aorta, PDGF-D was highly expressed in adventia, moderate in endothelia, and unidentified in media. Stable transfection of PDGF-D gene into vascular smooth muscle cells increased the cell migration by 2.2-fold, and the proliferation by 2.3-fold, respectively, and MMP-2 production and activity as well. These results support the fact that PDGF-D is involved in the formation of neointimal hyperplasia induced by balloon catheter injury and may serve as a target in preventing vascular restenosis after coronary angioplasty.

Animals↗