1,721,024 research outputs found
Fitting of monolithic (full-contour) versus layered lithium disilicate all-ceramic crowns
No full textOBJECTIVES. Monolithic all-ceramic fixed partial dentures are reported to be cost-effective and more resistant than layered counterparts. Monolithic crowns are more resistant to a type of failure called chipping and also aesthetically acceptable.Lithium disilicate blocks can be milled to obtain aesthetic, stronger and cheaper prosthetic manufacturing: without layering, lead times and costs are highly reduced.Although monolithic crowns seem to be more advantageous, during the layering process, crowns are submitted to the same thermic cycle as the monolithic, but this may yield different results as to marginal gaps. The aim of this study is to compare the fitting of monolithic and layered lithium disilicate all-ceramic crowns using the replica technique.MATERIALS AND METHODS. An upper incisor and a canine were prepared to receive ceramic restoration. For each tooth, 6 monolithic and 6 layered crowns were replicated using CAD/CAM technology and IPS e. max (R) CAD lithium disilicate blocks (Ivoclar-Vivadent, Shaan, Liechtenstein), thus obtaining 24 crowns divided into 4 groups: Group A, layered incisors; Group B, layered canines; Group C, monolithic incisors; Group D, monolithic canines. In order to determine the marginal gap, materials of two different colours were used for the replica technique. When the replica was obtained, it was cut into four pieces and observed through the microscope and the four marginal points could be measured thanks to the two different material colours.RESULTS. All crowns showed a marginal gap of over 100 mu m with different valuves in each group; such differences, however, are not statistically significant and are neither correlated with the fabrication technique, nor with the type of tooth.CONCLUSIONS. There is no statistical significance in the difference between monolithic and layered crowns marginal gaps. Although both types of crowns were obtained with the same CAD/CAM technology, the layering process is not involved in the precision level of marginal gaps
Exploring virtual prototypes using time-critical rendering techniques
Full text linkScientists at CRS4, the Center for Advanced Studies, Research and Development in Cagliari, Sardinia, Italy, have developed a time-critical rendering algorithm that relies upon a scene description in which objects are represented as multiresolution meshes. In collaboration with other European partners, this technique has been applied to the visual and collaborative exploration of large digital mock-ups.Pubblicat
Three-dimensional graphics
Full text linkThree-dimensional graphics is the area of computer graphics that deals with producing two-dimensional representations, or images, of three-dimensional synthetic scenes, as seen from a given viewing configuration. The level of sophistication of these images may vary from simple wire-frame representations, where objects are depicted as a set of segment lines, with no data on surfaces and volumes, to photorealistic rendering, where illumination effects are computed using the physical laws of light propagation. All the different approaches are based on the metaphor of a virtual camera positioned in 3D space and looking at the scene. Hence, independently from the rendering algorithm used, producing an image of the scene always requires the resolution of the following problems: 1. Modeling geometric relationships among scene objects, and in particular efficiently representing the situation in 3D space of objects and virtual cameras; 2. Culling and clipping, i.e. efficiently determining which objects are visible from the virtual camera; 3. Projecting visible objects on the film plane of the virtual camera in order to render them. This chapter provides an introduction to the field by presenting the standard approaches for solving the aforementioned problems.168-17
Deep panoramic depth prediction and completion for indoor scenes
Full text linkWe introduce a novel end-to-end deep-learning solution for rapidly estimating a dense spherical depth map of an indoor environment. Our input is a single equirectangular image registered with a sparse depth map, as provided by a variety of common capture setups. Depth is inferred by an efficient and lightweight single-branch network, which employs a dynamic gating system to process together dense visual data and sparse geometric data. We exploit the characteristics of typical man-made environments to efficiently compress multi-resolution features and find short- and long-range relations among scene parts. Furthermore, we introduce a new augmentation strategy to make the model robust to different types of sparsity, including those generated by various structured light sensors and LiDAR setups. The experimental results demonstrate that our method provides interactive performance and outperforms state-of-the-art solutions in computational efficiency, adaptivity to variable depth sparsity patterns, and prediction accuracy for challenging indoor data, even when trained solely on synthetic data without any fine tuning. (Figure presented.
Going Beyond Counting First Authors in Author Co-citation Analysis
Full text linkThe present study examines one of the fundamental aspects of author co-citation analysis (ACA) - the way co-citation
counts are defined. Co-citation counting provides the data on which all subsequent statistical analyses and mappings
are based, and we compare ACA results based on two different types of co-citation counting - the traditional type that
only counts the first one among a cited work's authors on the one hand and a non-traditional type that takes into
account the first 5 authors of a cited work on the other hand. Results indicate that the picture produced through this non-traditional author co-citation counting contains more coherent author groups and is therefore considerably clearer. However, this picture represents fewer specialties in the research field being studied than that produced through the traditional first-author co-citation counting when the same number of top-ranked authors is selected and analyzed. Reasons for these effects are discussed
Two examples of GPGPU acceleration of memory-intensive algorithm
No full textThe advent of GPGPU technologies has allowed for sensible speed-ups in many high-dimension, memory-intensive computational problems. In this paper we demonstrate the effectiveness of such techniques by describing two applications of GPGPU computing to two different subfields of computer graphics, namely computer vision and mesh processing. In the first case, CUDA technology is employed to accelerate the computation of approximation of motion between two images, known also as optical flow. As for mesh processing, we exploit the massively parallel architecture of CUDA devices to accelerate the face clustering procedure that is employed in many recent mesh segmentation algorithms. In both cases, the results obtained so far are presented and thoroughly discussed, along with the expected future development of the work
Variations on the Author
Full text link“Variations on the Author” discusses two of Eduardo Coutinho’s recent films (Um Dia na Vida, from 2010, and Últimas Conversas, posthumously released in 2015) and their contribution to the general question of documentary authorship. The director’s filmography is characterized by a consistent yet self-effacing form of authorial self-inscription: Coutinho often features as an interviewer that rather than express opinions propels discourses; an interviewer that is good at listening. This mode of self-inscription characterizes him as an author who is not expressive but who is nonetheless markedly present on the screen. In Um Dia na Vida, however, Coutinho is completely absent form the image, while Últimas Conversas, on the contrary, includes a confessional prologue that moves the director from the margins to the center of his films. This article examines the ways in which these works stand out in the filmography of a director who offers new insights into the notion of cinematic authorship
Appropriate Similarity Measures for Author Cocitation Analysis
Full text linkWe provide a number of new insights into the methodological discussion about author cocitation analysis. We first argue that the use of the Pearson correlation for measuring the similarity between authors’ cocitation profiles is not very satisfactory. We then discuss what kind of similarity measures may be used as an alternative to the Pearson correlation. We consider three similarity measures in particular. One is the well-known cosine. The other two similarity measures have not been used before in the bibliometric literature. Finally, we show by means of an example that our findings have a high practical relevance.information science;Pearson correlation;cosine;similarity measure;author cocitation analysis
- …
