Tooth Enamel Structure in the Koala, Phascolarctos cinereus: - Some Functional Interpretations

The purpose of this study is to determine whether the structural organization of Pattern 2 marsupial enamel in the Koala is disposed to resist wear on the sectorial crests of the molar teeth. The orientation of wear on the crests is uniformly delineated by parallel scratches on their polished surfaces. Twin blades, a leading and a trailing edge of enamel are formed on each crest by wear into dentine on which the differential wear at enamel to dentine interfaces indicates that the direction of wear is labial to lingual. 96 leading and trailing edges from 12 koala molars were examined by light and scanning electron microscopy as ground sections, polished and etched surfaces or polished and etched whole mount preparations sputter coated with gold. The results showed that the leading and trailing enamel edges are different in their thicknesses, and in the course of their rods. The rods in the thinner leading edge are angled at 25° to the long axis of the tooth and cross the worn surface al 60-70°. Trailing rods run at 5° to the long axis to cross the worn surface at 90°. The inter-rod sheets run parallel to the wear striations and thus hold the rods in palisades angled in the leading edge particularly to resist the vector of the occlusal forces in the direction of wear. Crystals in the rods emerge roughly perpendicular onto the worn surface which makes them more resistant to abrasion than those in the inter-rod substance which lie parallel to the worn surface and are more readily removed. Koala enamel on the sectorial crests is thus a simple Pattern 2 rod packing pattern but the angles of the rods and the alignment of the inter-rod substance appear to be adapted to resist occlusal forces and abrasion

Does the mind map learning strategy facilitate information retrieval and critical thinking in medical students?

<p>Abstract</p> <p>Background</p> <p>A learning strategy underutilized in medical education is mind mapping. Mind maps are multi-sensory tools that may help medical students organize, integrate, and retain information. Recent work suggests that using mind mapping as a note-taking strategy facilitates critical thinking. The purpose of this study was to investigate whether a relationship existed between mind mapping and critical thinking, as measured by the Health Sciences Reasoning Test (HSRT), and whether a relationship existed between mind mapping and recall of domain-based information.</p> <p>Methods</p> <p>In this quasi-experimental study, 131 first-year medical students were randomly assigned to a standard note-taking (SNT) group or mind map (MM) group during orientation. Subjects were given a demographic survey and pre-HSRT. They were then given an unfamiliar text passage, a pre-quiz based upon the passage, and a 30-minute break, during which time subjects in the MM group were given a presentation on mind mapping. After the break, subjects were given the same passage and wrote notes based on their group (SNT or MM) assignment. A post-quiz based upon the passage was administered, followed by a post-HSRT. Differences in mean pre- and post-quiz scores between groups were analyzed using independent samples <it>t</it>-tests, whereas differences in mean pre- and post-HSRT total scores and subscores between groups were analyzed using ANOVA. Mind map depth was assessed using the Mind Map Assessment Rubric (MMAR).</p> <p>Results</p> <p>There were no significant differences in mean scores on both the pre- and post-quizzes between note-taking groups. And, no significant differences were found between pre- and post-HSRT mean total scores and subscores.</p> <p>Conclusions</p> <p>Although mind mapping was not found to increase short-term recall of domain-based information or critical thinking compared to SNT, a brief introduction to mind mapping allowed novice MM subjects to perform similarly to SNT subjects. This demonstrates that medical students using mind maps can successfully retrieve information in the short term, and does not put them at a disadvantage compared to SNT students. Future studies should explore longitudinal effects of mind-map proficiency training on both short- and long-term information retrieval and critical thinking.</p