Theory of elasticity and electric polarization effects in the group-III nitrides

In this work, the properties of strained tetrahedrally bonded materials are explored theoretically, with special focus on group-III nitrides. In order to do so, a multiscale approach is taken: accurate quantitative calculations of material properties are carried out in a quantum first-principles frame, for small systems. These properties are then extrapolated and empirical methods are employed to make predictions for larger systems, such as alloys or nanostructures. We focus our attention on elasticity and electric polarization in semiconductors. These quantities serve as input for the calculation of the optoelectronic properties of these systems. Regarding the methods employed, our first-principles calculations use highly- accurate density functional theory (DFT) within both standard Kohn-Sham and generalized (hybrid functional) Kohn-Sham approaches. We have developed our own empirical methods, including valence force field (VFF) and a point-dipole model for the calculation of local polarization and local polarization potential. Our local polarization model gives insight for the first time to local fluctuations of the electric polarization at an atomistic level. At the continuum level, we have studied composition-engineering optimization of nitride nanostructures for built-in electrostatic field reduction, and have developed a highly efficient hybrid analytical-numerical staggered-grid computational implementation of continuum elasticity theory, that is used to treat larger systems, such as quantum dots.

Irish dental practitioners perceived barriers to the care of patients with special healthcare needs and the effect of postgraduate training

Inequalities in oral healthcare service provision to people with special health needs have been reported in the Republic of Ireland. These include higher unmet dental treatment needs and longer waiting period to access routine dental treatment than the general population. Aim: The aims of this study were to determine the groups of patients with special needs which pose a challenge to manage in the dental surgery and to examine perceived barriers to the care of these patients. We aimed to determine whether postgraduate training in the management of these patients increases the practitioners’ frequency of treatment and their desire for further training in this area. Methods: A questionnaire was used to survey 326 randomly selected dentists from the Dental Council’s register of dentists. Questionnaire and information sheets explaining the purpose of the survey, confidentiality and anonymity of the responses were posted to the dentists. Results: The results showed that children with intellectual disability posed the biggest challenge for dentists to manage in the dental surgery. Behaviour management issues and the degree of disability were perceived by many dentists as factors that would have high effects on their willingness to treat patients with special needs. Dentists who have postgraduate training in the management of patients with special needs were significantly more willing to treat these patients and to seek additional training in the future. Conclusion: There are links between the training and the willingness of practitioners to undertake dental treatment or patients with special healthcare needs.