Debbie Chachra

BackgroundUnderstanding more about student decisions to leave engineering may lead to higher retention. This study builds on the literature and focuses on the experiences of a cohort of students who aimed to complete their undergraduate work in 2007.Purpose (Hypothesis)This paper presents the outcomes of the longitudinal administration of the Persistence in Engineering survey. The goal was to identify correlates of persistence in undergraduate engineering education and professional engineering practice.Design/MethodThe survey was administered seven times over four years to a cohort of students who had expressed interest in studying engineering. At the end of the study, the participants were categorized as persisters or non‐persisters. Repeated measures analysis of variance was used, in conjunction with other approaches, to test for differences between the groups.ResultsPersisters and non‐persisters did not differ significantly according to the majority of the constructs. Nevertheless, parental and high school mentor influences as a motivation to study engineering, as well as confidence in math and science skills, were identified as correlates of persistence. Intention to complete an engineering major was also a correlate of persistence; it appears to decline sharply at least two semesters prior to students leaving engineering. The findings also suggest that there might be differences among non‐persisters when they are further grouped by when they leave engineering.ConclusionsFacilitating higher levels of mentor involvement before college might increase student motivation to study engineering, and also constitute a mechanism for fostering confidence in math and science skills. Since the intention to complete an engineering degree decreases well before students act, there may be opportunities for institutions to develop targeted interventions for students, and help them make informed decisions.

Records from the Multiple‐Institution Database for Investigating Engineering Longitudinal Development indicate that engineering students are typical of students in other majors with respect to: persistence in major; persistence by gender and ethnicity; racial/ethnic distribution; and grade distribution. Data from the National Survey of Student Engagement show that this similarity extends to engagement outcomes including course challenge, faculty interaction, satisfaction with institution, and overall satisfaction. Engineering differs from other majors most notably by a dearth of female students and a low rate of migration into the major. Noting the similarity of students of engineering and other majors with respect to persistence and engagement, we propose that engagement is a precursor to persistence. We explore this hypothesis using data from the Academic Pathways Study of the Center for the Advancement of Engineering Education. Further exploration reveals that although persistence and engagement do not vary as much as expected by discipline, there is significant institutional variation, and we assert a need to address persistence and engagement at the institutional level and throughout higher education. Finally, our findings highlight the potential of making the study of engineering more attractive to qualified students. Our findings suggest that a two‐pronged approach holds the greatest potential for increasing the number of students graduating with engineering degrees: identify programming that retains the students who come to college committed to an engineering major, and develop programming and policies that allow other students to migrate in. There is already considerable discourse on persistence, so our findings suggest that more research focus is needed on the pathways into engineering, including pathways from other majors.

This review focuses on the interaction of fluoride with the material properties of bone and teeth, which is of clinical, scientific, and public health interest. These tissues are composed primarily of collagen (protein) and hydroxyapatite (mineral), and their mechanical function depends on the properties of the constituents, their proportions, the interface, and the three-dimensional structure. Changing any of these may have clinical consequences. Fluoride interacts with mineralized tissues in a number of ways. At low doses, the fluoride may be passively incorporated into the mineral, stabilizing it against dissolution; this is one of the mechanisms by which municipally fluoridated water reduces the incidence of dental caries. At higher doses, such as those used for treatment of osteoporosis, the fluoride may alter the amount and structure of tissue present, including altering the interface between the collagen and mineral. At very high doses, skeletal and dental fluorosis occurs, characterized by debilitating changes in the skeleton and by marked mottling and discoloration of teeth, which may be accompanied by increased wear of the enamel. These effects have been observed in communities where the local drinking water has naturally high fluoride levels. Understanding the influence of fluoride on mineralized tissues is, therefore, of considerable significance.