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

Impact of Applications of Electronic Environment on the Concepts of Urban Planning—Postmodernism Era

In this humble research, the researcher sought to explain the overlapping effect of the post-modern electronic shopping technology on urban relations and the components of the urban environment in the context of the impact of the concepts of space, time, and movement, sense of place and components of the environment as a product of this use. It also aims to refer to the role of the Urban Planner in considering these impacts when developing the urban plan in the future. The researcher relied on the reference to the effects of this technology on human being, activity and land uses and their relationship with the components of the spatial urban environment. A questionnaire was prepared for a sample of stakeholders - users of this technique - and analysis of the results according to each activity. The results showed an increase in the business and a tendency to neutralize the effectiveness of the spatial location while using the electronic shopping tools. New patterns of entrepreneurs/ business were appeared depending on the size of investment in communication and electronic shopping. The results also showed that the sense of place is still present while making classic shopping against the time and cost offered electronically. The impact on the option of making or cancellation of tripswere an important component in this survey. The technology of communication and exchange of information within their virtual environment and communication enabled the provision of remote services and changed the concepts of movement and communication, sense of place. But, despite the rapid spread of these easy communication applications, the researcher believes that it still does not compensate for The urban side that fills the space and the real location and distributes activities on the ground. The integration of building components, components and tools of technology and communications can be beneficial to both directions. It Increases the use of communications for the largest number of users while at the same time supportingthe urban presence of an enhanced electronic presence of ground-based services

Towards Competency Based Undergraduate Curriculum In Pakistan

Knowledge in the biomedical field has grown exponentially, and is likely to keep on growing exponentially. Not only has the quantum of knowledge in the traditional subjects grown, but completely new subjects have been added in biomedical science. Thus, it is impossible for any one person to know everything about a subject. Hence,the need towards specialization has emerged in narrower and narrower sub-specialitie

Recognition of activities of daily living from topic model

Research in ubiquitous and pervasive technologies have made it possible to recognise activities of daily living through non-intrusive sensors. The data captured from these sensors are required to be classified using various machine learning or knowledge driven techniques to infer and recognise activities. The process of discovering the activities and activity-object patterns from the sensors tagged to objects as they are used is critical to recognising the activities. In this paper, we propose a topic model process of discovering activities and activity-object patterns from the interactions of low level state-change sensors. We also develop a recognition and segmentation algorithm to recognise activities and recognise activity boundaries. Experimental results we present validates our framework and shows it is comparable to existing approaches

QoS and security-aware task assignment and scheduling in real-time systems

Security issues in mission-critical real-time systems (e.g., command and control systems) are becoming increasingly important as there are growing needs for satisfying information assurance in these systems. In such systems, it is important to guarantee real-time deadlines along with the security requirements (e.g., confidentiality, integrity, and availability) of the applications. Traditionally, resource management in real-time systems has focused on meeting deadlines along with satisfying fault-tolerance and/or resource constraints. Such an approach is inadequate to accommodate security requirements into resource management algorithms. Based on the imprecise computation paradigm, a task can have several Quality of Service (QoS) levels, higher QoS result incurs higher computational cost. Similarly, achieving a higher level of confidentially requires stronger encryption, which incurs higher computational cost. Therefore, there exists a tradeoff between schedulability of the tasks on the one hand, and the accuracy (QoS) and security of the results produced on the other hand. This tradeoff must be carefully accounted in the resource management algorithms. In this context, this dissertation makes the following contributions: (i) formulation of scheduling problems accounting both deadline and security requirements of workloads in real-time systems, (ii) development of novel task allocation and scheduling algorithms for such workloads, (iii) and evaluation of the results through simulation studies and a limited test evaluations in one case. In particular, the following are the three key contributions. Firstly, the problem of scheduling a set of non-preemptable real-time tasks with security and QoS requirements with the goal of maximizing integrated QoS and security of the system is addressed. This problem is formulated as MILP, and then its complexity is proved to be NP-hard. An online efficient heuristic algorithm is developed as the problem is NP-hard. Simulation studies for a wide range of workload scenarios showed that the proposed algorithm outperforms a set of baseline algorithms. Further, the proposed algorithm\u27s performance is close to the optimal solution in a specific special case of the problem. Secondly, a static assignment and scheduling of a set of dependent real-time tasks, modeled as Directed Acyclic Graph (DAG), with security and QoS requirements in heterogeneous real-time system with the objective of maximizing Total Quality Value (TQV) of the system is studied. This problem is formulated as MINLP. Since this problem is NP-hard, a heuristic algorithm to maximize TQV while satisfying the security constraint of the system is developed. The proposed algorithm was evaluated through extensive simulation studies and compared to a set of baseline algorithms for variations of synthetic workloads. The proposed algorithm outperforms the baseline algorithms in all the simulated conditions for fully-connected and shared bus network topologies. Finally, the problem of dynamic assignment and scheduling of a set of dependent tasks with QoS and security requirements in heterogeneous distributed system to maximize the system TQV is addressed. Two heuristic algorithms to maximize TQV of the system are proposed because the problem is NP-hard. The proposed algorithms were evaluated by extensive simulation studies and by a test experiment in InfoSpher platform. The proposed algorithms outperform the baseline algorithms in most of the simulated conditions for fully-connected and shared bus network topologies

Seamless Vertical Handover in WiFi and WiMAX Networks using RSS and Motion Detection: An Investigation

In this paper, we propose a decision making algorithm for seamless vertical handover between WiFi hotspots and an overlay WiMAX network. The inputs to the algorithm are the WiFi received signal strength (RSS) and estimated end-to-end TCP handover latency. Simulation of the algorithm using Matlab® reveals that the distance from the WiFi reception boundary at which handover must be initiated if it is to be seamless increases with both end-to-end TCP/IP handover latency and the speed of the mobile terminal towards or away from the WiFi access point. We conclude that RSS-based seamless handovers need to be augmented with network layer information if they are to be optimal

Inclusive education: pedagogical approach to online versus face-to-face teaching

In today’s educational landscape, active learning is often overlooked during lectures, seminars, and tutorials. The aim of this study was to investigate perceptions of online and face-to-face lecture formats and their impact on the learning experiences of undergraduate dental students in Years 3–5. This qualitative study was conducted to investigate the effectiveness of different lecture formats at the Institute of Dentistry for undergraduate dental students in Years 3–5. There were two specific questions asked to dental undergraduate students with additional free-text questions. In total, 120 of 221 undergraduate students participated in this study between October 2019 and February 2020, and only 42 participants included the free-text comments. Three core themes related to the blended learning approach were identified: (1) scheduled versus recorded lectures, (2) duration of academic lectures, and (3) neurodiversity and learning experiences. The results showed that the learners perceived the traditional didactic lectures as the least effective format. There is not a “one fits all” lecture format that would accommodate a neurodiversity-based approach that focuses on the strengths, abilities, and interests of students. Hybrid lecture formats in combination with online teaching coupled with small group tutorials could be suggested. There is a unique challenge in the post-COVID-19 era for both educators and learners due to the lack of clinical practice and heavy reliance on online methods of teaching in Dentistry. Therefore, the implication of these results on the planning and financing of programmes could be discussed in Higher Education