Association between oral conditions and functional limitations in childhood.

The aim of this study was to evaluate the impact of oral conditions on functional limitations among preschoolers. A preschool-based, cross-sectional study was carried out with 843 preschoolers in Campina Grande, Brazil. Parents/caregivers answered a questionnaire addressing socio-demographic characteristics and perceptions regarding the general/oral health of their children as well as the Brazilian version of the Early Childhood Oral Health Impact Scale. The nonparametric Kruskal-Wallis test followed by Mann-Whitney test (α = 5%) was used to compare mean children's quality-of-life scores for each independent variable. Poisson regression analysis was used to test associations between the independent and dependent variables (difficulties eating, drinking and speaking) (α = 5%). The multivariate regression model involved a hierarchical approach with four levels (distal to proximal determinants): (i) socio-demographic aspects; (ii) health perceptions; (iii) oral conditions; and (iv) pain conditions. The prevalence of negative impact on function was 24.7% for eating/drinking and 8.0% for speaking. Significant associations were found between toothache and negative impact on eating/drinking (PR = 5.38; 95%CI: 3.20-9.02) as well as between high severity dental caries and negative impact on speaking (PR = 14.91; 95%CI: 1.98-112.32). Dental caries, traumatic dental injury and malocclusion were not significantly associated with a negative impact on eating or drinking. However, toothache was an indicator of negative impact on eating/drinking and dental caries severity was an indicator of negative impact on speaking.

ISIS Penning source extraction studies reveal the 3-dimensional Child-Langmuir effect.

The standard 1X ISIS negative Penning surface plasma source has reliably produced an H- beam for ISIS operations for 35 years. In order to meet the 60 mA, 2 ms, and 50 Hz beam current and duty cycle required for the front end test stand (Letchford et al., in Proceedings of IPAC2015, Richmond, VA, USA, 2015), a 2X scaled source has been developed [Faircloth et al., AIP Conf. Proc. 2052, 050004 (2018)]. The 2X source has a plasma chamber twice the linear dimensions of the 1X source. This paper investigates the comparison between different emission areas (plasma electrode aperture dimensions) for both the 1X and 2X sources. Slit and circular extraction schemes are studied. A 3D Child-Langmuir relationship is observed where the space charge limited current density depends on the aspect ratio of the extraction aperture.

Recent H- diagnostics, plasma simulations, and 2X scaled Penning ion source developments at the Rutherford Appleton Laboratory.

A vessel for extraction and source plasma analyses is being used for Penning H- ion source development at the Rutherford Appleton Laboratory. A new set of optical elements including an einzel lens has been installed, which transports over 80 mA of H- beam successfully. Simultaneously, a 2X scaled Penning source has been developed to reduce cathode power density. The 2X source is now delivering a 65 mA H- ion beam at 10% duty factor, meeting its design criteria. The long-term viability of the einzel lens and 2X source is now being evaluated, so new diagnostic devices have been installed. A pair of electrostatic deflector plates is used to correct beam misalignment and perform fast chopping, with a voltage rise time of 24 ns. A suite of four quartz crystal microbalances has shown that the cesium flux in the vacuum vessel is only increased by a factor of two, despite the absence of a dedicated cold trap. Finally, an infrared camera has demonstrated good agreement with thermal simulations but has indicated unexpected heating due to beam loss on the downstream electrode. These types of diagnostics are suitable for monitoring all operational ion sources. In addition to experimental campaigns and new diagnostic tools, the high-performance VSim and COMSOL software packages are being used for plasma simulations of two novel ion thrusters for space propulsion applications. In parallel, a VSim framework has been established to include arbitrary temperature and cesium fields to allow the modeling of surface physics in H- ion sources.