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

Distributions of Human Exposure to Ozone During Commuting Hours in Connecticut using the Cellular Device Network

Epidemiologic studies have established associations between various air pollutants and adverse health outcomes for adults and children. Due to high costs of monitoring air pollutant concentrations for subjects enrolled in a study, statisticians predict exposure concentrations from spatial models that are developed using concentrations monitored at a few sites. In the absence of detailed information on when and where subjects move during the study window, researchers typically assume that the subjects spend their entire day at home, school or work. This assumption can potentially lead to large exposure assignment bias. In this study, we aim to determine the distribution of the exposure assignment bias for an air pollutant (ozone) when subjects are assumed to be static as compared to accounting for individual mobility. To achieve this goal, we use cell-phone mobility data on approximately 400,000 users in the state of Connecticut during a week in July, 2016, in conjunction with an ozone pollution model, and compare individual ozone exposure assuming static versus mobile scenarios. Our results show that exposure models not taking mobility into account often provide poor estimates of individuals commuting into and out of urban areas: the average 8-hour maximum difference between these estimates can exceed 80 parts per billion (ppb). However, for most of the population, the difference in exposure assignment between the two models is small, thereby validating many current epidemiologic studies focusing on exposure to ozone

Risk Assessment as a Tool for Mobile Plant Operators for Sustainable Development: Lessons from the Western Australian Mining Industry

Mobile plant is used extensively not only in the Western Australian (WA) Mining Industry but internationally as well. The use of mobile plant has inherently high risk and every year is associated with a significant number of workplace fatalities and injuries. Prior to this research being conducted there was no specific data published related to mobile plants incidents and fatalities for the Western Australian mining industries. The aim of this research was to improve the safety performance of mobile plant operators in the Western Australia (WA) mining industry by identifying the causes of mobile plant incidents reported to Resources Safety between 1/1/2007 and 31/3/2020

Social innovation in Rural Development : a study about Uppsala and Tierp municipalities’ strategies

Målet med denna uppsats i landsbygdsutveckling är att undersöka hur två kommuner i Uppsala län, Uppsala och Tierps kommuner, uppfattar och arbetar med social innovation, samt vilken roll landsbygden spelar i arbetet. Uppsatsen är baserad på kvalitativa forskningsintervjuer med sex personer i de två kommunerna och analyseras utifrån teorier om social innovation i forskningslitteraturen, samt ur ett government och governance perspektiv. Studien visar att det finns en otydlighet kring begreppet social innovation som leder till att det ofta talas om i termer av sociala företag och sociala entreprenörer. Vidare analyseras hur kommunerna arbetar med sociala innovationer inom den privata, offentliga och idéburna sektorn. Genom t.ex. Idéburet Offentligt partnerskap (IOP) samt arbetar de tillsammans med organisationer som Mikrofonden och Coompanion i Uppsala Län. Studien avslutas med förslag för vidare forskning inom fältet för social innovation.In this thesis in Rural development the aim is to examine how two municipalities in Uppsala county, Uppsala and Tierp municipalities understand and work with social innovation, and to what extent the countryside is part of this work. The thesis is based on qualitative interviews with six employees in the two municipalities and is analyzed through theories on social innovation in the research literature, and from a ‘government & governance’ perspective. The study shows that there is complexity around the term social innovation and it is often spoken about in terms of social enterprises or social actors. The latter part describes how these two municipalities work with social innovation in the private, public and the civic sector. Through for instance Civic-public partnership (IOP) agreements and in collaborations with organizations such as Microfund and Coompanion in Uppsala county. The paper ends with recommendations for further research in the field of social innovation

Capacitive Micromachined Ultrasound Transducers for Non-Destructive Testing Applications

The need for using ultrasound non-destructive testing (NDT) to characterize, test and detect flaws within metals, led us to utilize Capacitive Micromachined Ultrasound Transducers (CMUTs) in the ultrasound NDT field. This is due to CMUT's large bandwidths and high receive sensitivity, to be a suitable substitute for piezoelectric (PZT) transducers in NDT applications. The basic operational test of CMUTs, conducted in this research, was carried out based on a pulse-echo technique by propagating acoustic pulses into an object and analyzing the reflected signals. Thus, characterizing the tested material, measuring its dimension, and detecting flaws within it can be achieved. Throughout the course of this research, the fundamental parameters of CMUT including pull-in voltage and resonance frequency were initially calculated analytically and using Finite Element Analysis (FEA). Afterward, the CMUT was fabricated out of two mechanically bonded wafers. The device's movable membrane (top electrode) and stationary electrode (bottom electrode) were made out of Boron-doped Silicon. The two electrodes were electrically isolated by an insulation layer containing a sealed gap. The CMUT was then tested and characterized to analyze its performance for NDT applications. In-immersion characterization revealed that the 2.22 MHz CMUT obtained a -6 dB fractional bandwidth of 189%, and a receive sensitivity of 31.15 mV/kPa, compared to 45% and 4.83 mV/kPa of the PZT probe. A pulse-echo test, performed to examine an aluminum block with and without flaws, showed success in distinguishing the surfaces and the flaws of the tested sample

The Most Alluring Future Destination For Foreign Direct Investments: A Case Study Of India.

Nearly two decades of economic liberalization, coupled with robust domestic demand, an emerging middle class, a young population, a high return on investment , cost competitiveness and an epic pool of talent endures to transform India as one of the most preferred destinations for FDI. India’s domestic demand-driven growth model is playing a catalyst role in enticing FDIs in the country. India is now transitioning into the next phase of the growth cycle where manufacturing might play a leading role in determining its growth trajectory. During 2007-11, India’s Top Five FDI Destinations (i.e. Bangalore, New Delhi, Pune, Mumbai and Chennai) enticed 1826 FDI projects creating above 378,548 jobs. We have enough evidence to comprehend that India is the next most alluring destination for FDIs. Hence, it is evident that India is the future Destination for FDIs. Keywords: India, Foreign Direct Investment (FDI), Domestic Demand-Driven Growth, India’s Top Five FDI Destinations, Information Technology (IT), Case Study of India

Construction of nonuniform periodic wavelet frames on non-Archimedean fields

In real life applications not all signals are obtained by uniform shifts; so there is a natural question regarding analysis and decompositions of these types of signals by a stable mathematical tool. Gabardo and Nashed, and Gabardo and Yu filled this gap by the concept of nonuniform multiresolution analysis and nonuniform wavelets based on the theory of spectral pairs for which the associated translation set $\Lambda= \{0,r/N\}+2\mathbb{Z}$ is no longer a discrete subgroup of $\mathbb{R}$ but a spectrum associated with a certain one-dimensional spectral pair and the associated dilation is an even positive integer related to the given spectral pair. In this paper, we introduce a notion of nonuniform periodic wavelet frame on non-Archimedean field. Using the Fourier transform technique and the unitary extension principle, we propose an approach for the construction of nonuniform periodic wavelet frames on non-Archimedean fields

Arab Media during the Arab Spring in Egypt and Tunisia: Time for Change

“Change” and “Purification” are two key words you often hear nowadays among Egyptian and Tunisian journalists. For them, the revolution has not ended… it has just begun. Much as the Egyptian and the Tunisian people were eagerly waiting to overcome their fear of the police state, the journalists of both countries are now waiting for another seminal moment in the history of their profession. It is time to free the media from ex-regime allies. Tunisian media demonstrations succeeded in changing editorial teams on national television and newspapers while the ongoing Egyptian demonstrations are calling for the election of a new board for their association and to bring new blood to the stagnant national media. “It is a seminal moment in the history of our profession. Our media will only be purified and changed when ex-regime allies leave,” said Wael Abul Saoud of Akhbar Alyoum newspaper, during a demonstration opposite the Egyptian Cabinet’s headquarters in Cairo, calling for the firing of the editors-in-chief appointed by the former regime

Seamless Air Travel: Siproavi\u27s Technological Advancements

Siproavi\u27s Role in Revolutionizing Air Travel: In our pursuit of revolutionizing air travel, Siproavi introduces a comprehensive suite of services catering to seasoned travelers and newcomers alike: Ticket Booking: Our user-friendly platform empowers travelers to swiftly search, compare, and book flights that align seamlessly with their preferences and schedules. This service has substantially reduced booking time for travelers, often completing the process within 2 minutes. Baggage Handling: We have conquered the age-old woes of baggage handling. Siproavi\u27s cutting-edge services ensure the safety and security of your belongings from check-in to arrival, resulting in a 30% decrease in baggage-related complaints. Transportation: The stress of getting to and from the airport is eliminated with Siproavi\u27s efficient transportation solutions. These seamlessly integrate with your travel itinerary, reducing airport traffic congestion by 20% and ensuring a smooth transition from home to your final destination. AI bot CABi, our AI-powered virtual assistant, efficiently compares cab prices from various websites and providers. Passengers can effortlessly book the most cost-effective cab options, eliminating the need to visit multiple websites or apps. Adding CABi extends Siproavi\u27s service spectrum, further enhancing the passenger experience. It reflects Siproavi\u27s commitment to making air travel as stress-free and enjoyable as possible from the beginning of the journey. E-Passport Services: Siproavi\u27s innovative e-passport services significantly streamline immigration processes, saving passengers an average of 45 minutes per flight and enhancing the convenience of international travel. This contributes to a better understanding of passenger data, benefiting travelers and the industry