Barriers to routine dental care for children with special health care needs.

PURPOSE: The aim of this mixed method study was to identify barriers for children with special health care needs (SHCN) to receiving routine preventive dental care following restorative dental care with general anesthesia (GA). METHODS: Electronic health records were reviewed for inclusion criteria and demographic data. Caregivers of children with SHCN were contacted to participate in qualitative interviews. Interview topics explored child, family, and community level influences to accessing routine dental care. Qualitative analysis identified key themes of barriers and enablers to care. RESULTS: A total of 1708 children received dental care with GA during the 2-year study period, of which 498 (29.16%) had a diagnosis of a SHCN. The most common type of SHCN was neurodevelopmental disorders (28.51%). The mean age at time of GA was 8.6 years. Fifty caregivers completed interviews. Identified barriers to obtaining routine dental care included child stress/anxiety, finding an accepting provider, dismissive providers, and proximity of provider/transportation to dental care. Enablers to obtaining care included effective behavior management, continuity of provider/care, positive provider attitude, and referral to an accepting provider. CONCLUSION: Adequately trained and local providers with an accepting attitude are essential to enabling children with SHCN to obtain equitable access to routine dental care.

A novel approach using nonlinear surfaces for dynamic aperture optimization in MBA synchrotron light sources.

MBA cell-based synchrotron light sources have enabled an unprecedented increase in beam coherence and brightness, greatly benefiting the scientific disciplines that rely on X-ray techniques. However, controlling the electron dynamics is a theoretical and technological challenge, due to the large number of parameters to adjust and constraints to satisfy when designing modern synchrotrons. Having versatile tools for the description and manipulation of electron dynamics could favor the design of these accelerators and lead to progress on several fronts in the understanding of matter. In this paper, a formalism based on the use of nonlinear geometric surfaces represented by polynomial quasi-invariants, to analyze and optimize the dynamic aperture of electrons in MBA storage rings, is introduced. The formalism considers on- and off-momentum particle dynamics. Within the optimization scheme, different objective functions defined in terms of the nonlinear surfaces, which are minimized using genetic algorithm methods, are proposed. A remarkable horizontal dynamic aperture exceeding 19 mm is obtained for the design particle of a synchrotron model with 86 pm [Formula: see text] rad emittance along with a dynamic aperture above 5 mm for momentum deviations of ± 3[Formula: see text]. According to the results presented, this formalism could be greatly useful for manipulating the dynamical properties of electrons in synchrotrons light sources close to the diffraction limit.

Increasing beam stability zone in synchrotron light sources using polynomial quasi-invariants.

The objective of this article is to propose a scheme to increase the stability zone of a charged particles beam in synchrotrons using a suitable objective function that, when optimized, inhibits the resonances onset in phase space and the dynamic aperture of electrons in storage rings can be improved. The proposed technique is implemented by constructing a quasi-invariant in a neighborhood of the origin of the phase space, then, by using symbolic computation software, sets of coupled differential equations for functions involved in nonlinear dynamics are obtained and solved numerically with periodic boundary conditions. The objective function is constructed by proposing that the innermost momentum solution branch of the polynomial quasi-invariant approaches to the corresponding ellipse of the linear dynamics. The objective function is optimized using a genetic algorithm, allowing the dynamic aperture to be increased. The quality of results obtained with this scheme are compared with particle tracking simulations performed with available software in the field, showing good agreement. The scheme is applied to a synchrotron light source model that can be classified as third generation due to its emittance.