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Remarkable Resilience Of Teeth (How Are Teeth So Brittle Yet So Resilient), Paul J. Constantino May 2012

Remarkable Resilience Of Teeth (How Are Teeth So Brittle Yet So Resilient), Paul J. Constantino

Biological Sciences Faculty Research

Tooth enamel is inherently weak, with fracture toughness comparable with glass, yet it is remarkably resilient, surviving millions of functional contacts over a lifetime. We propose a microstructural mechanism of damage resistance, based on observations from ex situ loading of human and sea otter molars (teeth with strikingly similar structural features). Section views of the enamel implicate tufts, hypomineralized crack-like defects at the enamel–dentin junction, as primary fracture sources. We report a stabilization in the evolution of these defects, by ‘‘stress shielding’’ from neighbors, by inhibition of ensuing crack extension from prism interweaving (decussation), and by self-healing. These factors, coupled …


Toward The History Of Study Of Symbiogenesis: On The English Translation Of B. M. Kozo-Polyansky’S A New Principle Of Biology (1924), Victor Fet Jan 2012

Toward The History Of Study Of Symbiogenesis: On The English Translation Of B. M. Kozo-Polyansky’S A New Principle Of Biology (1924), Victor Fet

Biological Sciences Faculty Research

We reproduce the text by Victor Fet, which was read on 6 October 2011 at the Moscow Society of Naturalists during the presentation of new book translation (B.M. Kozo- Polyansky. Symbiogenesis: A New Principle of Evolution / transl. by Victor Fet; ed. by Victor Fet & Lynn Margulis. Cambridge, Mass.: Harvard University Press, 2010. 138 p.) This half- forgotten book by Boris M. Kozo-Polyansky was known only by name to Western biologists. Victor Fet gives a brief history of this new translation, enthusiastically initiated and supported by Lynn Margulis (1938–2011), a famous naturalist who was always eager to gave credit …