Among the challenges within the big data era, analyses of high multidimensional data are still an open research area. As a result, several multidimensional projections techniques have been developed ...to reduce data dimensionality, becoming a powerful visualization and visual analytics tool. In order to ensure the projection quality, it is necessary to assess the lower-dimensional embedding by using different datasets configurations as input and analyzing evaluation metrics. However, it is not always clear to the user how the number of dimensions, instances or clusters, called factors, can affect the projection mapping and its quality regarding different projection techniques and assessment metrics. This work aims to address how much the factors affect each response variable through performance evaluation planning. We present an evaluation approach that carries out a more in-depth multidimensional projection analysis supported by the factorial design. Through the comparison of two multidimensional projections, it allows a better understanding of how distinct dataset properties can influence on quality metrics results.
This study aimed to evaluate the cause-effect relationship between canal preparation with ProTaper Universal (PTU) system and dentinal defects formation using micro-computed tomography (micro-CT) ...analysis. Forty mesial canals of mandibular molars with a type II Vertucci's canal configuration were scanned at an isotropic resolution of 14.16 µm. The sample was assigned to an experimental (n = 30) and a control (n = 10) groups, and the mesial canals were prepared with PTU system up to F2 instrument. The specimens from the experimental group were scanned and the cross-section images of the mesial roots, before and after preparation, were screened to identify the presence of dentinal defects. In the control group, the specimens were sectioned perpendicularly to the long axis of the root into 1-mm-thick slices (n = 80) and examined under optical microscope. Once a dentinal defect was detected, the slice was scanned through micro-CT. In the experimental group, dentinal micro-cracks were observed in 4,828 slices (24.04%). In all cross-section images, dentinal defects identified in the postoperative images were already present in the corresponding preoperative image. In the control group, 13 out of 80 slices (16.25%) had at least one dentinal defect visualized under stereomicroscopy, which was identified after a further micro-CT scanning. Micro-CT showed reliability as similar as optical microscopy in detecting dentinal defects, adding the possibility of tracking the dentinal tissue, before and after canal preparation, and providing a clear visualization of micro-cracks. Root canal preparation with PTU system did not induce the formation of new dentinal defects.
The aim of this study was to compare the percentage of non-instrumented area of root canals prepared with different enlargements using single-file reciprocating systems (Reciproc and WaveOne) and a ...conventional multi-file rotary (BioRaCe) system by micro-computed tomographic analysis. Thirty mesial roots of mandibular molars with moderate curvature (10° to 20°) presenting a type II Vertucci canal configuration and similar internal volume were chosen and scanned at an isotropic resolution of 14.16 µm. The sample was assigned to 3 groups (n=10) according to the system used for root canal preparation: Reciproc, WaveOne, and BioRaCe groups. Second and third scans were taken after the canals were prepared with instruments sizes 25 and 40, respectively. The recorded images of the surface area voxels of the canals, before and after preparation were examined from the furcation level to the apex to quantify the non-instrumented surface. Statistical data were compared using GLM for repeated-measures with a significance level set at 5%. Instrumentation systems did not influence the percentage of untouched root canal surfaces (p=0.690) whilst a significant reduction in the percentage of static voxels was observed after the enlargement of the root canal (p=0.010) in all groups (p=0.507). None of the systems was able to prepare the entire surface area of the mesial root canal of mandibular molars. The increased final apical size resulted in a significant positive effect on the shaping ability of the tested systems.
The constant need of sharing data in information systems leads to the development of more complex and creative solutions to the physical or cost limitations of the nowadays technology. The main ...problems of a distributed system include: the huge information volume by time interval carried over the network infrastructure, and the confidentiality of the ongoing data. Going into the media transmission sub area, there are even more restrictions to be considered. Error or delay, for example, can drastically impact the user experience in real-time transmission. In this context, this paper proposes a tool for performing efficient and secure distribution and encryption of video streams. This tool was implemented and applied in several contexts. In order to validate the tool in a set of possible situations, tests of the video reflector were made using several sets of parameters evolving variations of video codecs and presence or absence of cryptography.
