X-Ray Microanalysis of Dentin: A Review

The aim of this review was to present a condensed summary of the literature on X-ray microanalysis of dentin, including both energy-dispersive (EDS) and wavelength-dispersive (WDS) analysis. Estimations of concentrations by XMA of dentin should be regarded as semiquantitative values. The Ca level in rat odontoblasts was elevated in the secreting end of the cell body. In predentin Ca accumulated at a concentration of 2% that of mineralized dentin. In coronal dentin the peritubular areas were hypermineralized (Ca, P, Mg). Primary caries lesions showed a decrease of Ca, P, Mg and Cl, and usually an increase of S and Zn. The mineralized surface often present contained especially high concentrations of F and K. Considerable uptake of various ions in cavity walls exposed to filling materials was assessed: from silver amalgam, Zn and Sn, from silicate cement and glassionomer cement F, Al and Zn, and from zinc oxide-eugenol cement, Zn. The highest F concentrations following topical application were found with solutions of TiF4 and with the varnishes Duraphat® and FluorProtector®. Dentin wall lesions adjacent to amalgam fillings exhibited considerably reduced Ca and P values, but concomitantly considerable amounts of Zn and Sn, that explained the increased radiopacity seen in some microradiographs

Thyroxine and triiodothyronine degradation in lines of pigs selected for rate of gain and thickness of backfat

International audienc

Hurricanes, fertility, and family structure:a study of early 20th century Jamaica

This study investigates the impact of hurricanes on fertility and the role of family structure in early 20th century Jamaica. Importantly, this was a time period in which there were no storm warnings or other formal disaster mitigation policies in place, allowing one to arguably identify the causal effect of storms on births without any policy interference. To this end, historical hurricane tracks and an exhaustive register of births are used to create a parish level monthly data set on births and hurricane destruction for the period 1901 to 1929. The regression analysis reveals that hurricanes impact excess births for close to 2 years after the event, with the average damaging storm causing a reduction in births of around 13%. Most of the negative effect is due to lower post-storm fertility rather than a fall in births by women affected while pregnant. There is no evidence that the fall in births was driven by fertile females dying as a result of the hurricane. Similarly, there was no discernible differential impact between single mother and two parent registered births, where the impact on the latter appears to be driven by non-marital conjugal unions

Nursing and midwifery students\u27 experiences and perception of their clinical learning environment in Malawi: A mixed-method study

© 2020 The Author(s). Background: The clinical learning environment is an important part of the nursing and midwifery training as it helps students to integrate theory into clinical practice. However, not all clinical learning environments foster positive learning. This study aimed to assess the student nurses and midwives\u27 experiences and perception of the clinical learning environment in Malawi. Methods: A concurrent triangulation mixed methods research design was used to collect data from nursing and midwifery students. Quantitative data were collected using a Clinical Learning Environment Inventory, while qualitative data were collected using focus group discussions. The Clinical Learning Environment Inventory has six subscales of satisfaction, involvement, individualisation, innovation, task orientation and personalisation. The focus group interview guide had questions about clinical learning, supervision, assessment, communication and resources. Quantitative data were analysed by independent t-test and multivariate linear regression and qualitative data were thematically analysed. Results: A total of 126 participants completed the questionnaire and 30 students participated in three focus group discussions. Satisfaction subscale had the highest mean score (M = 26.93, SD = 4.82) while individualisation had the lowest mean score (M = 18.01, SD =3.50). Multiple linear regression analysis showed a statistically significant association between satisfaction with clinical learning environment and personalization (β = 0.50, p = \u3c 0.001), and task orientation (β =0.16 p = \u3c 0.05). Teaching and learning resources, hostile environment, poor relationship with a qualified staff, absence of clinical supervisors, and lack of resources were some of the challenges faced by students in their clinical learning environment. Conclusion: Although satisfaction with clinical learning environment subscale had the highest mean score, nursing and midwifery students encountered multifaceted challenges such as lack of resources, poor relationship with staff and a lack of support from clinical teachers that negatively impacted on their clinical learning experiences. Training institutions and hospitals need to work together to find means of addressing the challenges by among others providing resources to students during clinical placement