Background Self-efficacy has been shown to be positively related to undergraduate engi-

Locomotion imposes some of the highest loads upon the skeleton, and diverse bone designs have evolved to withstand these demands. Excessive loads can fatally injure organisms; however, bones have a margin of extra protection, called a 'safety factor' (SF), to accommodate loads that are higher than normal. The extent to which SFs might vary amongst an animal's limb bones is unclear. If the limbs are likened to a chain composed of bones as 'links', then similar SFs might be expected for all limb bones because failure of the system would be determined by the weakest link, and extra protection in other links could waste energetic resources. However, Alexander proposed that a 'mixed-chain' of SFs might be found amongst bones if: (1) their energetic costs differ, (2) some elements face variable demands, or (3) SFs are generally high. To test whether such conditions contribute to diversity in limb bone SFs, we compared the biomechanical properties and locomotor loading of the humerus and femur in the tiger salamander (Ambystoma tigrinum). Despite high SFs in salamanders and similar sizes of the humerus and femur that would suggest similar energetic costs, the humerus had lower bone stresses, higher mechanical hardness and larger SFs. SFs were greatest in the anatomical regions where yield stresses were highest in the humerus and lowest in the femur. Such intraspecific variation between and within bones may relate to their different biomechanical functions, providing insight into the emergence of novel locomotor capabilities during the invasion of land by tetrapods.

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To increase the number of science, technology, engineering, and mathematics (STEM) graduates, educators need to identify ways to increase student persistence from entry until graduation. The objectives of this study are to determine (1) if motivation affects learning outcomes in engineering service courses and (2) whether students' level of motivation tracks with specific engineering disciplines. Students enrolled in a sophomorelevel engineering service course were surveyed to examine their motivation in engineering service courses and to assess the relationship between their motivation and their achievement and desire to persist in the engineering discipline. The survey measures for self-efficacy, task value, and achievement goals in engineering were created and evaluated during an initial pilot study. Initial results showed internal consistency among the items in each measure.