A Comparison of Three-Dimensional Printing Technologies on the Precision, Trueness, and Accuracy of Printed Retainers

Purpose: The aim of this study was to evaluate the differences in the precision, trueness, and accuracy of 3D printed orthodontic clear retainers produced using printer systems with various printing technologies. Methods: Retainers (n=15) were printed using four different 3D printers: a stereolithography (SLA) printer, two different digital light processing (DLP and cDLP) printers, and a polyjet photopolymer (PPP) printer. The 3D printed retainers were transformed into a digital file through a cone-beam computed tomography scan that was compared to the original image using a 3D superimposition analysis software. At previously chosen landmarks (R6, L6, R3, L3, R1, L1) retainers were compared to the reference model. The intercanine and the intermolar width measurements were also analyzed for deviations between the samples and the original file. A discrepancy up to 0.25mm was considered clinically acceptable. Precision of printers was evaluated on 5 randomly chosen samples. Trueness was determined by comparing the measurements on printed retainers to those on the original image file. Root mean square (RMS) and percent of points within the tolerance level (inTOL) were also calculated with respect to precision and trueness for each retainer. Samples were analyzed for intra-printer reliability (precision), and inter-printer trueness. Statistical significance was set at P\u3c0.05. Results: Interrater correlation coefficient indicated good agreement and all measurements were within 0.10mm at least 95% of the time. Statistically significant differences were found between printer types among each of the 6 landmarks and the arch widths. When evaluating inTOL and RMS, statistically significant differences in both median precision and trueness among each printer type were found. SLA and PPP printing technologies exhibited both excellent precision and trueness. Conclusion: Retainers fabricated by SLA, DLP, cDLP, and PPP technologies were shown to be clinically acceptable and accurate compared to the standard reference file. SLA and PPP printers showed greater accuracy, and the DLP and cDLP printers exhibited greater precision. The PPP printer had the most accurate intra-arch measurements followed by the SLA printer, and therefore, based on their high trueness and precision values, were deemed to be the most accurate overall

Tungsten-Based Composites for Nuclear Fusion Applications

This chapter provides a comprehensive knowledge about the potential role of tungsten-based composites in fusion reactors and the research work which has been done in this very important area of nuclear materials. The characteristics of tungsten, which make it the most potential candidate for plasma-facing applications, have been presented along with the shortcomings in pure tungsten. The research work that has been done so far in the field of tungsten-based composites to overcome the problems with pure tungsten has been included. The fabrication, characterization, types of reinforcements and the classes of composites have been reviewed. The behavior of tungsten-based composites under various kinds of loads (i.e. mechanical and thermal) and environments (radiations and oxidizing etc.) has been summarized

Spatiotemporal Calibration of Atmospheric Nitrogen Dioxide Concentration Estimates From an Air Quality Model for Connecticut

A spatiotemporal calibration and resolution refinement model was fitted to calibrate nitrogen dioxide (NO$_2$) concentration estimates from the Community Multiscale Air Quality (CMAQ) model, using two sources of observed data on NO$_2$ that differed in their spatial and temporal resolutions. To refine the spatial resolution of the CMAQ model estimates, we leveraged information using additional local covariates including total traffic volume within 2 km, population density, elevation, and land use characteristics. Predictions from this model greatly improved the bias in the CMAQ estimates, as observed by the much lower mean squared error (MSE) at the NO$_2$ monitor sites. The final model was used to predict the daily concentration of ambient NO$_2$ over the entire state of Connecticut on a grid with pixels of size 300 x 300 m. A comparison of the prediction map with a similar map for the CMAQ estimates showed marked improvement in the spatial resolution. The effect of local covariates was evident in the finer spatial resolution map, where the contribution of traffic on major highways to ambient NO$_2$ concentration stands out. An animation was also provided to show the change in the concentration of ambient NO$_2$ over space and time for 1994 and 1995.Comment: 23 pages, 8 figures, supplementary materia

Coupling of Smoothened to inhibitory G proteins reduces voltage-gated K

SMO (Smoothened), the central transducer of Hedgehog signaling, is coupled to heterotrimeric Gi proteins in many cell types, including cardiomyocytes. In this study, we report that activation of SMO with SHH (Sonic Hedgehog) or a small agonist, purmorphamine, rapidly causes a prolongation of the action potential duration that is sensitive to a SMO inhibitor. In contrast, neither of the SMO agonists prolonged the action potential in cardiomyocytes from transgenic GiCT/TTA mice, in which Gi signaling is impaired, suggesting that the effect of SMO is mediated by Gi proteins. Investigation of the mechanism underlying the change in action potential kinetics revealed that activation of SMO selectively reduces outward voltage-gated K+ repolarizing (Kv) currents in isolated cardiomyocytes and that it induces a down-regulation of membrane levels of Kv4.3 in cardiomyocytes and intact hearts from WT but not from GiCT/TTA mice. Moreover, perfusion of intact hearts with Shh or purmorphamine increased the ventricular repolarization time (QT interval) and induced ventricular arrhythmias. Our data constitute the first report that acute, noncanonical Hh signaling mediated by Gi proteins regulates K+ currents density in cardiomyocytes and sensitizes the heart to the development of ventricular arrhythmias. © 2018 Cheng et al

A Socio-Legal Study on Vaccine Tourism in the Context of Covid-19 Travel Restrictions

The COVID-19 pandemic has affected the tourism industry harshly. The most effective way to steer clear of the virus is global vaccination. A novel concept of vaccine tourism arises from vaccine manufacturing corporations' limited stock and production capacity. The current paper aims to demystify the socio-legal and ethical underpinnings of vaccine tourism as well as analyze the restrictions on international travel imposed by major countries. The research critically examines key issues considering the literature's current arguments and integrates the current developments and challenges in the field of vaccine tourism. The paper addresses the fact that, in the current circumstances of travel restrictions, insufficiency of raw materials, ambiguous policies, vaccine passport authenticity, skewed distribution, and scarcity of vaccines around the world, the implementation of vaccine tourism is a big challenge. The study tries to understand the emerging concept of vaccine tourism and the major challenges to its growth. Vaccine tourism may be an instrument to revive the tourism sector post-COVID; therefore, understanding the current emerging issues around it would be significant for tourism literature. Doi: 10.28991/ESJ-2023-07-05-012 Full Text: PD

Social determinants of Health and Alcohol consumption in the UK

  Addressing the social determinants of health (SDH) and health inequities are essential for successfully combating alcohol-related harm. In U.K, excessive consumption of alcohol is a huge public health concern. An estimated 9 million adults drink at level that increase the risk of harm to their health; 1.6 million adults in England have some degree of alcohol dependence; and of these some 250,000 are believed to be moderately or severely dependent and may benefit from intensive specialist treatment. To be able to devise effective action, it is essential to comprehend these inequities in the healthcare system. Health inequities are not solely related to access to health care services; there are many other determinants related to living and working conditions, as well as the overall macro-policies prevailing in a country. The key intention of this review was to critically analyse the degree to which social determinants have impacted on excess alcohol consumption. A comprehensive approach to reduce inequities in alcohol-related harm requires action that includes mix of long- and short-term impacts, addressing the consequences and the root causes of inequities, and acting on both individuals and environments. Whereas, consequences of harmful alcohol use are more severe for those already experiencing social exclusion. We suggest that (1) the effective legislation, (2) modifying marketing strategies, (3) enhancing cooperation with regional organizations, (4) more effectively implementing existing regulation and (5) consulting expert will enhance SDH for this vulnerable population