Linear non-threshold: separating facts from fiction.

The Linear Non-Threshold (LNT) process is used by virtually all governmental agencies to compute incidence of cancer as a consequence of exposure to a carcinogen. This comment applies the concept of Best Available Science (BAS) Metrics for Evaluation of Scientific Claims (MESC) derived from BAS to issues related to reliability of LNT hypothesis. This paper identifies the level of maturity of the LNT hypothesis and the associated uncertainties.

Improvements of the CARTE thermochemical code dedicated to the computation of properties of explosives.

In the field of detonation science or shock physics, predicting the thermo- dynamic properties and chemical compositions of detonation products of CHON systems (outcome of the decomposition of explosives) over a wide range of temperature and pressure with a very small computational cost is of great importance. Thermochemical codes such as the CARTE code use several methods published in the literature to compute the properties of these CHON systems. In this work, we evaluate the accuracy of the recently improved KLRR perturbation method and we propose a new mixing rule to reduce the fluid mixture to an effective pure fluid. Then, the results obtained with these two contributions are presented.

Student learning preferences and teaching implications.

One of the most serious challenges that dental educators face today is improving the level of student satisfaction with the curriculum and learning environment. To determine whether a particular teaching method might enhance student satisfaction with the learning process, a learning preference survey linked to sensory modalities was given to students in the four classes of the Temple University School of Dentistry. New Zealand educator Neil Fleming developed the survey called VARK (an acronym for Visual, Aural, Read/Write, and Kinesthetic) in 1998. The purpose of this study was to measure the distribution of learning preference mean scores of the dental students and note any significant differences among classes, gender, and a sample population determined using 31,243 participants on the VARK website. Results clearly demonstrate that the dominant preference distributions for the two populations (dental student and sample population) are different. In particular, the proportions of learners who selected visual or kinesthetic are significantly different for the two populations, while the proportions of learners who selected aural or read/write are not significantly different. Dental students prefer visual learning at a higher percentage and kinesthetic learning at a lower percentage than the sample population measured in the VARK website. Inter-class differences varied, and gender differences were not significant. The distribution of dental student scores shows a preference for instructors who use strong visual presentations and facilitate note-taking during lectures. Dental educators should be aware of these differences in order to explore opportunities for making the educational experience more productive and enjoyable.

The role of scientific consensus organizations in the development of standards.

Scientific research, discovery, and application have had, and continue to have, a significant impact on society. The description of how various scientific disciplines have impacted society would be a daunting task. The evolution of scientific organizations and their roles in development of occupational and environmental standards are described. Following the enactment of various laws in the U.S., the authors suggest that the role of scientific organizations is to ensure that the best available scientific information is provided to regulatory agencies, who in turn use that information in the development of standards. The authors also describe the role of stakeholders in the development of standards.

Are traditional cognitive tests useful in predicting clinical success?

The purpose of this research was to determine the predictive value of the Dental Admission Test (DAT) for clinical success using Ackerman's theory of ability determinants of skilled performance. The Ackerman theory is a valid, reliable schema in the applied psychology literature used to predict complex skill acquisition. Inconsistent stimulus-response skill acquisition depends primarily on determinants of cognitive ability. Consistent information-processing tasks have been described as "automatic," in which stimuli and responses are mapped in a manner that allows for complete certainty once the relationships have been learned. It is theorized that the skills necessary for success in the clinical component of dental schools involve a significant amount of automatic processing demands and, as such, student performance in the clinics should begin to converge as task practice is realized and tasks become more consistent. Subtest scores of the DAT of four classes were correlated with final grades in nine clinical courses. Results showed that the DAT subtest scores played virtually no role with regard to the final clinical grades. Based on this information, the DAT scores were determined to be of no predictive value in clinical achievement.

Electroglottographic evaluation of the swallow.

The feasibility of using the electroglottograph (EGG) to record and measure aspects of the swallow was tested in six nonimpaired, two parkinsonian, and two dysphagic subjects. Low-frequency changes in tissue impedance across the neck were recorded with an EGG during deglutition. On six nonimpaired subjects, EGG waveforms were consistently monophasic and appeared to be well timed with laryngeal height changes. The waveforms of the two dysphagic subjects differed markedly from those of the nonimpaired subjects, and their timing and shapes were consistent with videofluoroscopic descriptions of those of the dysphagic subjects. The two parkinsonian patients also showed aberrant waveform patterns. These observations suggest that use of the EGG has strong potential as a quantitative technique for swallowing evaluation, therapy, and research.