Tuesday, September 23, 2008

Head Butting Goats and FEM: Teaser

Finally! The first paper from my dissertation has made it into press:

Farke, A. A. 2008. Frontal sinuses and head butting in goats: a finite element analysis. Journal of Experimental Biology 211: 3085-3094. doi: 10.1242/jeb.019042

Abstract: Frontal sinuses in goats and other mammals have been hypothesized to function as shock absorbers, protecting the brain from blows during intraspecific combat. Furthermore, sinuses are thought to form through removal of `structurally unnecessary' bone. These hypotheses were tested using finite element modeling. Three-dimensional models of domesticated goat (Capra hircus) skulls were constructed, with variable frontal bone and frontal sinus morphology, and loaded to simulate various head-butting behaviors. In general, models with sinuses experienced higher strain energy values (a proxy for shock absorption) than did models with unvaulted frontal bones, and the latter often had higher magnitudes than models with solid vaulted frontal bones. Furthermore, vaulted frontal bones did not reduce magnitudes of principal strain on the surface of the endocranial cavity relative to models with unvaulted frontal bones under most loading conditions. Thus, these results were only partially consistent with sinuses, or the bone that walls the sinuses, acting as shock absorbers. It is hypothesized that the keratinous horn sheaths and cranial sutures are probably more important for absorbing blows to the head. Models with sinuses did exhibit a more `efficient' distribution of stresses, as visualized by histograms in which models with solid frontal bones had numerous unloaded elements. This is consistent with the hypothesis that sinuses result at least in part from the removal of mechanically unnecessary bone.


To get a PDF of this paper, try this link first. If you don't have institutional access via the link, email me at andyfarke [at] hotmail [dot] com, and I'll send you a (legal) link for a free download (more on this below).

Within the next few days, I'll have a post summarizing this research. For now, I'll just talk a little about. . .

JEB and Open Access
Journal of Experimental Biology is not an open access journal - although it does allow that option for a healthy (unaffordable, in my case) fee. But, they present an admirable compromise - all papers become freely available 6 months after initial publication. Although a full open access model would be ideal, I think the publishers have found a good middle ground. The publishers get their due priority, and folks who are willing to wait a few months will get full access to all papers (or can email the authors for a reprint). If only more upper tier journals were to follow this route!

Authors get a link that allows up to 50 free downloads of the PDF (for use before the PDF goes free in six months). As mentioned above, anyone who would like this link should email me at andyfarke [at] hotmail [dot] com. Out of respect for JEB (because I think they're one of the few commercial journals that might have researchers' interests at heart), I won't be posting the PDF outright at this time. But, don't be afraid to email me if you want a copy!