Joseph Carlin

Joseph Carlin - B.S. 2009

Joseph Carlin - B.S. 2009

My project focused on the luminescence of silver-bearing hydrothermal calcite veins from Batopilas, Mexico, which is in southwestern Chihuahua. Luminescence is when an external energy source excites electrons in a mineral to a higher energy state, and then as they return to ground state they emit the extra energy as visible light. I used photoluminescence (stimulus from a UV light) and cathodoluminescence (stimulus from an electron beam). There were a variety of photoluminescent colors in the calcites ranging from red-violet to pink to orange. The red-violet and pink photoluminescent samples also contained metallic minerals such as galena, sphalerite, and native silver whereas the orange samples were barren. This makes photoluminescent color a useful indicator in the field for finding metallic mineral-bearing veins.

Digital endocast of left petrosal of Noctilio albiventris in posterior view. A. Unmodified petrosal, B. Bone rendered transparent, C. Isolated digital endocast. The different colors represent the cavities that contain the different organs within the petrosal.

Digital endocast of left petrosal of Noctilio albiventris in posterior view. A. Unmodified petrosal, B. Bone rendered transparent, C. Isolated digital endocast. The different colors represent the cavities that contain the different organs within the petrosal.

The vestibular apparatus in bats occupies a significantly lower percentage of the petrosal cavity compared to terrestrial mammals (the mean percentage for bats is 29.9% compared to a mean percentage of 43.7% for terrestrial mammals). This finding is analogous to a reduction of the vestibular apparatus which has been well documented in whales and supports the hypothesis that moving in a three-dimensional fluid media introduces selective pressure favoring smaller vestibular structures. The difference was found to be statistically significant.

Honors Advisor:

Dr. Chris Bell