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

Toward an Affective Problematics: A Deleuze-Guattarian Reading of Morality and Friendship in Toni Morrison’s Sula

It might sound rather convincing to assume that we owe the pleasure of reading the novel form to our elemental repository of physical perception, to our feelings. This would be true only if mere feelings could add up to something more than just emotions, to some deep understanding of the human. After all, a moment of epiphany, where we begin to realize things that dramatically disturb our normal state of mind, is not just emotional, nor indeed a simple moment. Despite its root in the corporeal, a mo(ve)ment of affective realization reaches beyond the realm of the human and opens up the plane of virtual potentials. In this work, we intend to map out the points and relations of affective singularity that pervade the narrative of Toni Morrison’s Sula (1973). Also, we will discuss how these mo(ve)ments of sensation give form to Sula’s and Nel’s experiences and contribute to an affective transformation in morality and friendship

Fiscal Scenario of South Asian Countries: Implications for Economic Growth and Poverty Alleviation

Sustainable economic growth and Poverty alleviation is a principal objective of the developing countries. The present study aims to historically review of fiscal policy and its consequences for the economic development of the four South Asian economies i.e. Pakistan, India, Sri Lanka and Bangladesh. Confined revenues and savings coupled with rising expenditures have caused situation of persistent fiscal deficit over the years. Coupled with that countries are also facing current account deficit. Resultantly, ‘Twin Deficit problem’ emerged, and it is filled by public deb. Consequently countries have to spend considerable portion of their GDP on interest payments of the loans. The need to service debt obligation is undermining economic performance and resulting in collapse of development planning. Because debt obligations and expenditure on debt servicing become a resource drain for already limited revenues and is halting economic growth and poverty reduction efforts.Fiscal Policy, Poverty, Economic growth

Shortest closed billiard orbits on convex tables

Given a planar compact convex billiard table $T$, we give an algorithm to find the shortest generalised closed billiard orbits on $T$. (Generalised billiard orbits are usual billiard orbits if $T$ has smooth boundary.) This algorithm is finite if $T$ is a polygon and provides an approximation scheme in general. As an illustration, we show that the shortest generalised closed billiard orbit in a regular $n$-gon $R_n$ is 2-bounce for $n \ge 4$, with length twice the width of $R_n$. As an application we obtain an algorithm computing the Ekeland-Hofer-Zehnder capacity of the four-dimensional domain $T \times B^2$ in the standard symplectic vector space $\mathbb{R}^4$. Our method is based on the work of Bezdek-Bezdek and on the uniqueness of the Fagnano triangle in acute triangles. It works, more generally, for planar Minkowski billiards.Comment: 16 pages, 11 figure

Short run and long run dynamics of impact of health status on economic growth Evidence from Pakistan

The paper investigates the impacts of different health indicators on Economic growth in Pakistan. The Cointegration and Error Correction techniques were applied on the time series data of Pakistan for the period of 1972-2006. We find that Per capita GDP is positively influenced by health indicators in the long run and health indicators are having significant impact on per capita GDP. However, in the short run the health indicators fails to put significant impact on per capita GDP. It reveals that health indicators have a long run impact on economic growth. . It suggests that impact of health is only a long run phenomenon and in the short run there is no significant relationship exists between health variables and economic growth. The major policy implication of the study is that if we desire a high levels of per capita income, we can achieve it by increasing and improving the stock of health human capital, especially if current stocks are at lower end. Moreover, study also points out a rather diminutive role of public health expenditure in determining the per capita GDP.Health human capital; Economic growth; Per capita GDP; Cointegration; Error Correction

Common security issues and challenges in wireless sensor networks and IEEE 802.11 wireless mesh networks

Both Wireless Mesh Network (WMN) and Wireless Sensor Network (WSN) are multi-hop wireless networks. WMN is an emerging community based integrated broadband wireless network which ensures high bandwidth ubiquitous internet provision to users, while, WSN is application specific and ensures large scale real-time data processing in complex environment. Both these wireless networks have some common vulnerable features which may increase the chances of different sorts of security attacks. Wireless sensor nodes have computation, memory and power limitations, which do not allow for implementation of complex security mechanism. In this paper, we discuss the common limitations and vulnerable features of WMN and WSN, along with the associated security threats and possible countermeasures. We also propose security mechanisms keeping in view the architecture and limitations of both. This article will serve as a baseline guide for the new researchers who are concern with the security aspects of WMN and WSN

Absolute neutrino masses

We discuss the possibility of using experiments timing the propagation of neutrino beams over large distances to help determine the absolute masses of the three neutrinos.Comment: 3 pages, 2 figure