On the formulation of environmental fugacity models and their numerical solutions.

Multimedia models based on chemical fugacity, solved numerically, play an important role in investigating and quantifying the environmental fate of chemicals such as persistent organic pollutants. These models have been used extensively in studying the local and global distribution of chemicals in the environment. The present study describes potential sources of error that may arise from the formulation and numerical solution of environmental fugacity models. The authors derive a general fugacity equation for the rate of change of mass in an arbitrary volume (e.g., an environmental phase). Deriving this general equation makes clear several assumptions that are often not articulated but can be important for successfully applying multimedia fugacity models. It shows that the homogeneity of fugacity and fugacity capacity in a volume (the homogeneity assumption) is fundamental to formulating discretized fugacity models. It also shows that when using the fugacity rather than mass as the state-variable, correction terms may be necessary to accommodate environmental factors such as varying phase temperatures and volume. Neglecting these can lead to conservation errors. The authors illustrate the manifestation of these errors using heuristic multimedia fugacity models. The authors also show that there are easily avoided errors that can arise in mass state-variable models if variables are not updated appropriately in the numerical integration scheme. Environ Toxicol Chem 2016;35:2182-2191. © 2016 SETAC.

Dental rounds: an evolving process of curriculum integration at the LSU School of Dentistry.

With the support for curriculum change expressed by the American Dental Education Association's Commission on Change and Innovation in Dental Education (ADEA CCI), the Louisiana State University Health Sciences Center School of Dentistry (LSUSD) initiated a course that vertically integrates the basic sciences and clinical sciences and promotes critical thinking. The resulting Dental Rounds course includes presentations by D3 and D4 students on interesting clinical cases, which the entire student body is required to attend. Following the third year of the program, a formal evaluation was conducted, in which surveys were disseminated to students, recent graduates, and faculty members to collect feedback on the efficacy of the course, its perceived value, and its success as an educational tool. Of the 242 students and graduates who were sent surveys, 181 responded, a 74 percent response rate. Of the eighty full-time faculty members, sixty-one responded, a 76 percent response rate. Most respondents reported that the objectives of the course were being achieved, but they identified case-related discussion as an area for strengthening critical thinking skills. As a result, modifications were planned to include formal participation of D1 and D2 students in the presentations, less frequent sessions to accommodate more complete cases, more emphasis on basic science, more structured mentoring, and a modified question format. Dental Rounds was a necessary integration step in dental education for LSUSD, and it is anticipated that the planned modifications will lead to strengthening of critical thinking skills in both students and faculty.

Anthropogenic changes to seawater buffer capacity combined with natural reef metabolism induce extreme future coral reef CO2 conditions.

Ocean acidification, via an anthropogenic increase in seawater carbon dioxide (CO2 ), is potentially a major threat to coral reefs and other marine ecosystems. However, our understanding of how natural short-term diurnal CO2 variability in coral reefs influences longer term anthropogenic ocean acidification remains unclear. Here, we combine observed natural carbonate chemistry variability with future carbonate chemistry predictions for a coral reef flat in the Great Barrier Reef based on the RCP8.5 CO2 emissions scenario. Rather than observing a linear increase in reef flat partial pressure of CO2 (pCO2 ) in concert with rising atmospheric concentrations, the inclusion of in situ diurnal variability results in a highly nonlinear threefold amplification of the pCO2 signal by the end of the century. This significant nonlinear amplification of diurnal pCO2 variability occurs as a result of combining natural diurnal biological CO2 metabolism with long-term decreases in seawater buffer capacity, which occurs via increasing anthropogenic CO2 absorption by the ocean. Under the same benthic community composition, the amplification in the variability in pCO2 is likely to lead to exposure to mean maximum daily pCO2 levels of ca. 2100 µatm, with corrosive conditions with respect to aragonite by end-century at our study site. Minimum pCO2 levels will become lower relative to the mean offshore value (ca. threefold increase in the difference between offshore and minimum reef flat pCO2 ) by end-century, leading to a further increase in the pCO2 range that organisms are exposed to. The biological consequences of short-term exposure to these extreme CO2 conditions, coupled with elevated long-term mean CO2 conditions are currently unknown and future laboratory experiments will need to incorporate natural variability to test this. The amplification of pCO2 that we describe here is not unique to our study location, but will occur in all shallow coastal environments where high biological productivity drives large natural variability in carbonate chemistry.

Electronic textbooks as a professional resource after dental school.

In two previous studies of dental students' attitudes about the VitalSource Bookshelf, a digital library of dental textbooks, students expressed negative opinions about owning and reading electronic textbooks. With the assumption that dentists would find the digital textbooks useful for patient care, the authors surveyed recent graduates to determine if their attitude toward the VitalSource Bookshelf had changed. A brief survey was sent to 119 alumni from the classes of 2009 and 2010 of one U.S. dental school. Forty-seven (39.5 percent) completed the questionnaire. Eighteen respondents (48.3 percent) reported using the e-textbooks often or sometimes. The twenty-nine dentists who said they have not used the collection since graduation reported preferring print books or other online sources or having technical problems when downloading the books to a new computer. Only five respondents selected the VitalSource Bookshelf as a preferred source of professional information. Most of the respondents reported preferring to consult colleagues (37.8 percent), the Internet (20 percent), or hardcopy books (17.8 percent) for information. When asked in an open-ended question to state their opinion of the Bookshelf, nineteen (42.2 percent) responded positively, but almost one-third of these only liked the search feature. Six respondents reported that they never use the program. Twenty-two said they have had technical problems with the Bookshelf, including fifteen who have not been able to install it on a new computer. Many of them said they have not followed up with either the dental school or VitalSource support services to overcome this problem. Our study suggests that dentists, similar to dental students, dislike reading electronic textbooks, even with the advantage of searching a topic across more than sixty dental titles.

Incoming dental students' expectations and acceptance of an electronic textbook program.

Since 2005, the Louisiana State University Health Sciences Center School of Dentistry has required the VitalSource Technologies, Inc. Bookshelf as the textbook program for all dental students. In a 2008 survey, four classes of dental students expressed dissatisfaction with most features of the bookshelf. With the expectation that incoming students would be more accustomed and amenable to digital textbooks and to further determine student attitudes toward electronic textbooks, we developed two surveys for first-year dental students in the class of 2013. The sixty-five first-year students received a survey (S1) one week before they were introduced to the e-textbook program. Questions centered on their undergraduate experience with e-books and their expectations of studying with an electronic textbook collection. In the second survey (S2), sent nine months later, the questions focused on students' opinion of the VitalSource Bookshelf. Forty-five students (69.2 percent) completed the S1 survey. Of those, thirty-six (80 percent) responded that they never used e-textbooks in college. Of the nine students who responded that they used e-books, only two liked them without reservations. The response rate to S2 increased to fifty students (77 percent). After using VitalSource for nine months, thirty-three students (66 percent) indicated a preference for reading print textbooks, compared to forty-seven students (57.3 percent) of the four classes surveyed in 2008. Although we expected incoming dental students to have had previous experience with e-textbooks, only nine students had used e-books in college courses. Few students indicated preference for e-textbooks, and over half of the group was undecided. After experience with VitalSource for first-year courses, students indicated that they like VitalSource for the ability to search for specific topics across the entire collection of dental books, but not for reading large amounts of text.

Dental students' attitudes towards digital textbooks.

Dental students at the Louisiana State University School of Dentistry (LSUSD) have participated in the VitalSource Bookshelf digital textbook program for the last four years. The Bookshelf, a collection of downloadable textbooks, includes the Contemporary Dental Library (CDL), a basic package of sixty books, plus additional titles selected by course directors. A survey was sent to students in the four LSUSD classes to assess satisfaction with the program. Eighty-two (34.2 percent) students completed the survey. In addition, exit interviews of graduating seniors contained a question on the Bookshelf. In both the survey and the exit interview, LSUSD students overwhelmingly expressed dissatisfaction with reading extensive amounts of text online and indicated a preference for printed books. Some students also resented paying for books in the CDL that were not required by instructors and felt that, considering how infrequently they used the Bookshelf, the cost was too high.