944 resultados para Segmentation of threedimensional images
Resumo:
The aim of this study was to assess qualitatively, by means of SEM images, the cleaning of the dentin walls of root canals after chemical-surgical preparation using Endo-PTC cream with 0.5% and 1% sodium hypochlorite and different final irrigating solutions. Seventy-two single-rooted human teeth were divided into eight groups and prepared using Endo-PTC cream with sodium hypochlorite (NaOCl) at different concentrations, and irrigated with NaOCl at different concentrations. Final irrigation was performed with either EDTA-T or EDTA-C. The best results were obtained with Group 1, followed by Groups 5, 2, 7, 8, 3, 6 and 4. We can conclude that the use of 0.5% NaOCl during instrumentation and final flush of the root canals was more efficient in cleaning than was 1% sodium hypochlorite. EDTA-T was more efficient in removing smear layer than EDTA-C, and the cervical third presented better cleaning of the root canal walls than did the middle third, which showed cleaner dentin walls than the apical third.
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Question: How can the coexistence of savanna and forest in Amazonian areas with relatively uniform climates be explained? Location: Eastern Marajo Island, northeast Amazonia, Brazil. Methods: The study integrated floristic analysis, terrain morphology, sedimentology and delta(13)C of soil organic matter. Floristic analysis involved rapid ecological assessment of 33 sites, determination of occurrence, specific richness, hierarchical distribution and matrix of floristic similarity between paired vegetation types. Terrain characterization was based on analysis of Landsat images using 4(R), 5(G) and 7(B) composition and digital elevation model (DEM). Sedimentology involved field descriptions of surface and core sediments. Finally, radiocarbon dating and analysis of delta(13)C of soil profile organic matter and natural ecotone forest-savanna was undertaken. Results: Slight tectonic subsidence in eastern Marajo Island favours seasonal flooding, making it unsuitable for forest growth. However, this area displays slightly convex-up, sinuous morphologies related to paleochannels, covered by forest. Terra-firme lowland forests are expanding from west to east, preferentially occupying paleochannels and replacing savanna. Slack, running water during channel abandonment leads to disappearance of varzea/gallery forest at channel margins. Long-abandoned channels sustain continuous terra-firme forests, because of longer times for more species to establish. Recently abandoned channels have had less time to become sites for widespread tree development, and are either not vegetated or covered by savanna. Conclusion: Landforms in eastern Marajo Island reflect changes in the physical environment due to reactivation of tectonic faults during the latest Quaternary. This promoted a dynamic history of channel abandonment, which controlled a set of interrelated parameters (soil type, topography, hydrology) that determined species location. Inclusion of a geological perspective for paleoenvironmental reconstruction can increase understanding of plant distribution in Amazonia.
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This study aimed to describe the benefits of memory training for older adults with low education. Twenty-nine healthy older adults with zero to two years of formal education participated. Sixteen participants received training based on categorization (categorization group = CATG) and 13 received training based on mental images (imagery group = IMG). One group served as control for the other because they trained with different strategies. Training was offered in eight sessions of 90 minutes. The participants were evaluated pre- and posttraining. IMG improved performance in episodic memory tests and had reduced depressive symptoms. CATG increased the use of categorization but did not increase performance in episodic memory tests. Results suggest that the strategy based on the creation of mental images was more effective for older adults with low formal education.
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The increasing adoption of information systems in healthcare has led to a scenario where patient information security is more and more being regarded as a critical issue. Allowing patient information to be in jeopardy may lead to irreparable damage, physically, morally, and socially to the patient, potentially shaking the credibility of the healthcare institution. Medical images play a crucial role in such context, given their importance in diagnosis, treatment, and research. Therefore, it is vital to take measures in order to prevent tampering and determine their provenance. This demands adoption of security mechanisms to assure information integrity and authenticity. There are a number of works done in this field, based on two major approaches: use of metadata and use of watermarking. However, there still are limitations for both approaches that must be properly addressed. This paper presents a new method using cryptographic means to improve trustworthiness of medical images, providing a stronger link between the image and the information on its integrity and authenticity, without compromising image quality to the end user. Use of Digital Imaging and Communications in Medicine structures is also an advantage for ease of development and deployment.
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One of the challenges in scientific visualization is to generate software libraries suitable for the large-scale data emerging from tera-scale simulations and instruments. We describe the efforts currently under way at SDSC and NPACI to address these challenges. The scope of the SDSC project spans data handling, graphics, visualization, and scientific application domains. Components of the research focus on the following areas: intelligent data storage, layout and handling, using an associated “Floor-Plan” (meta data); performance optimization on parallel architectures; extension of SDSC’s scalable, parallel, direct volume renderer to allow perspective viewing; and interactive rendering of fractional images (“imagelets”), which facilitates the examination of large datasets. These concepts are coordinated within a data-visualization pipeline, which operates on component data blocks sized to fit within the available computing resources. A key feature of the scheme is that the meta data, which tag the data blocks, can be propagated and applied consistently. This is possible at the disk level, in distributing the computations across parallel processors; in “imagelet” composition; and in feature tagging. The work reflects the emerging challenges and opportunities presented by the ongoing progress in high-performance computing (HPC) and the deployment of the data, computational, and visualization Grids.
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This paper reviews the potential use of three types of spatial technology to land managers, namely satellite imagery, satellite positioning systems and supporting computer software. Developments in remote sensing and the relative advantages of multispectral and hyperspectral images are discussed. The main challenge to the wider use of remote sensing as a land management tool is seen as uncertainty whether apparent relationships between biophysical variables and spectral reflectance are direct and causal, or artefacts of particular images. Developments in satellite positioning systems are presented in the context of land managers’ need for position estimates in situations where absolute precision may or may not be required. The role of computer software in supporting developments in spatial technology is described. Spatial technologies are seen as having matured beyond empirical applications to the stage where they are useful and reliable land management tools. In addition, computer software has become more user-friendly and this has facilitated data collection and manipulation by semi-expert as well as specialist staff.
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Background: Concerns exist regarding the effect of radiation dose from paediatric pelvic CT scans and the potential later risk of radiation-induced neoplasm and teratogenic outcomes in these patients. Objective: To assess the diagnostic quality of CT images of the paediatric pelvis using either reduced mAs or increased pitch compared with standard settings. Materials and methods: A prospective study of pelvic CT scans of 105 paediatric patients was performed using one of three protocols: (1) 31 at a standard protocol of 200 mA with rotation time of 0.75 s at 120 kVp and a pitch factor approximating 1.4; (2) 31 at increased pitch factor approaching 2 and 200 mA; and (3) 43 at a reduced setting of 100 mA and a pitch factor of 1.4. All other settings remained the same in all three groups. Image quality was assessed by radiologists blinded to the protocol used in each scan. Results: No significant difference was found between the quality of images acquired at standard settings and those acquired at half the standard mAs. The use of increased pitch factor resulted in a higher proportion of poor images. Conclusions: Images acquired at 120 kVp using 75 mAs are equivalent in diagnostic quality to those acquired at 150 mAs. Reduced settings can provide useful imaging of the paediatric pelvis and should be considered as a standard protocol in these situations.
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It has been claimed that the symptoms of post-traumatic stress disorder (PTSD) can be ameliorated by eye-movement desensitization-reprocessing therapy (EMD-R), a procedure that involves the individual making saccadic eye-movements while imagining the traumatic event. We hypothesized that these eye-movements reduce the vividness of distressing images by disrupting the function of the visuospatial sketchpad (VSSP) of working memory, and that by doing so they reduce the intensity of the emotion associated with the image. This hypothesis was tested by asking non-PTSD participants to form images of neutral and negative pictures under dual task conditions. Their images were less vivid with concurrent eye-movements and with a concurrent spatial tapping task that did not involve eye-movements. In the first three experiments, these secondary tasks did not consistently affect participants' emotional responses to the images. However, Expt 4 used personal recollections as stimuli for the imagery task, and demonstrated a significant reduction in emotional response under the same dual task conditions. These results suggest that, if EMD-R works, it does so by reducing the vividness and emotiveness of traumatic images via the VSSP of working memory. Other visuospatial tasks may also be of therapeutic value.
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Adjustments during postural control have been recognized in the process of the integration of movement and cognition. The objective of the present work was to describe postural changes and to verify if there is a correlation between postural adjustment and attention span in 7-month-old infants during 1 min of viewing an animated puppet. Method: Twenty-nine healthy infants (14 males) born from 31 to 39 weeks (median 36) were placed in a prone position and filmed watching a puppet during I min. The analysis of the images allowed us to catalogue the changes in position, the frequency of these changes, and the attention span. The following items were quantified: total number of infant positions, positions with weight transfer, changes in support, axis, decubitus, trunk and cervical movements, timing and pauses in visual attention. Results: Twenty-one infants stayed in the prone position during most of the recording, and eight chose sitting position before starting the session. Two groups were studied according to the main position throughout the filming, one in prone and the other in sitting positions, although they could rolling or crawling. For prone group the attention span was positively correlated with the number of positions with weight transfer (r = 0.53, p = 0.04), negatively correlated with trunk movements (r = -0.63, p = 0.01), and not correlated with birth or current weight. This work suggests that changes in the trunk movements and weight transfer are different traits related to the attention in 7-month-old infants. (C) 2008 Elsevier B.V.. All rights reserved.
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Objective: Clinical evaluation of the stomatognathic system is indispensable for the diagnosis of orofacial myofunctional disorders. In order to obtain a more precise diagnosis, the protocol of orofacial myofunctional evaluation with scores (OMES protocol) (Int. J. Pediatr. Otorhinolaryngol. 72 (2008) 367-375) was expanded in terms of number of items and scale amplitude. The proposal of this study is to describe the expanded OMES protocol (OMES-E) for the evaluation of children. Validity of the protocol, reliability of the examiners and agreement between them were analyzed, as also were the sensitivity, specificity and predictive values of the instrument. Methods: The sample consisted of videorecorded images of 50 children, 25 boys (mean age = 8.4 years, SD = 1.8) and 25 girls (mean age = 8.2 years, SD = 1.7) selected at random from 200 samples. Three speech therapists prepared for orofacial myofunctional evaluation participated as examiners (E). The OMES and OMES-E protocols were used for evaluation on different days. E1 evaluated all images, E2 analyzed children with recordings from 1 to 25 and E3 analyzed children with recordings from 26 to 50. The validity of OMES-E was analyzed by comparing the instrument to the OMES protocol using the Pearson correlation test complemented with the split-half reliability test (p < 0.05). The linear weighted Kappa coefficient of agreement (Kw`), the sensitivity, specificity and predictive values and the prevalence of OMD were calculated. Results: There was a statistically significant correlation between the OMES and OMES-E protocols (0.79 > r < 0.94, p < 0.01) and a significant test-retest correlation with the OMES-E (0.75 > r < 0.86, p < 0.01), with a reliability range of 0.86-0.93. The correlation and reliability coefficients between examiners were: E1 x E2 (r = 0.74, 0.84), E1 x E3 (r = 0.70, 0.83) (p < 0.01). Kw` coefficients with moderate and good strength predominated. The OMES-E protocol presented mean sensitivity = 0.91, specificity = 0.77, positive predictive value = 0.87 and negative predictive value = 0.85. The mean prevalence of OMD was 0.58. Conclusion: The OMES-E protocol is valid and reliable for orofacial myofunctional evaluation. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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Chorea-acanthocytosis (ChAc) is an uncommon autosomal recessive disorder due to mutations of the VPS13A gene, which encodes for the membrane protein chorein. ChAc presents with progressive limb and orobuccal chorea, but there is often a marked dysexecutive syndrome. ChAc may first present with neuropsychiatric disturbance such as obsessive-compulsive disorder (OCD), suggesting a particular role for disruption to striatal structures involved in non-motor frontostriatal loops, such as the head of the caudate nucleus. Two previous studies have suggested a marked reduction in volume in the caudate nucleus and putamen, but did not examine morphometric change. We investigated morphometric change in 13 patients with genetically or biochemically confirmed ChAc and 26 age- and gender-matched controls. Subjects underwent magnetic resonance imaging and manual segmentation of the caudate nucleus and putamen, and shape analysis using a non-parametric spherical harmonic technique. Both structures showed significant and marked reductions in volume compared with controls, with reduction greatest in the caudate nucleus. Both structures showed significant shape differences, particularly in the head of the caudate nucleus. No significant correlation was shown between duration of illness and striatal volume or shape, suggesting that much structural change may have already taken place at the time of symptom onset. Our results suggest that striatal neuron loss may occur early in the disease process, and follows a dorsal-ventral gradient that may correlate with early neuropsychiatric and cognitive presentations of the disease. (C) 2010 Elsevier Ireland Ltd. All rights reserved.
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The anatomosurgical segmentation of the arteries of the spleen was studied in 31 deer of the species Mazama gouazoubira and Blastocerus dichotomus by means of vascular injection with latex and vinyl acetate and radiographic examination. The arteria lienalis penetrated through the hilus lienis in 87% of the cases, whereas an extrahilar artery was present in the other cases. An extraparenchymal division of the lineal artery into two, three or four segmental arteries was observed in 74% of the cases. Anastomoses between intraparenchymal arterial branches were rare and of a reduced calibre.
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Objectives. The diagnosis of root fractures by conventional radiographs is still difficult because of limitations of 2D images. Cone-beam volumetric tomography improves the diagnosis capacity in dentistry, such as increased radiation dose to the patient and presence of artifacts on the image. Study design. This study compared the images obtained on conventional periapical radiographs and 3D scans (Accuitomo 3DX) for the diagnosis of root fractures. Twenty patients with suspected root fractures were submitted to examination by periapical radiography and CBCT. Two professionals, unaware of the symptomatology, examined these radiographs and CBCT images according to pre-established scores, which were later checked against the signs and symptoms. Results. The results revealed statistical difference for cone-beam volumetric tomography compared with conventional radiographs in the diagnosis of root fractures. Conclusion. It could be concluded that cone-beam volumetric tomography was better than conventional radiography in the diagnosis of root fractures, thereby constituting an excellent alternative for diagnosis in general practice. (Oral Surg Oral Med Oral Pathol Oral Radiol Endod 2009; 108: 270-277)
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Objectives: To evaluate the influence of JPEG quality factors 100, 80 and 60 on the reproducibility of identification of cephalometric points on images of lateral cephalograms, compared with the Digital Imaging and Communications in Medicine (DICOM) format. Methods: The sample was composed of 30 images of digital lateral cephalograms obtained from 30 individuals (15 males and 15 females) on a phosphor plate system in DICOM format. The images were converted to JPEG with quality factors 100, 80 and 60 with the aid of software, adding up to 90 images. The 120 images (DICOM, JPEG 100, 80 and 60) were blinded and 12 cephalometric points were identified on each image by three calibrated orthodontists, using the x-y coordinate system, on a cephalometric software. Results: The results revealed that identification of cephalometric points was highly reproducible, except for the point Orbitale (Or) on the x-axis. The different file formats did not present a statistically significant difference. Conclusions: JPEG images of lateral cephalograms with quality factors 100, 80 and 60 did not present alterations in the reproducibility of identification of cephalometric points compared with the DICOM format. Good reproducibility was achieved for the 12 points, except for point Or on the x-axis. Dentomaxillofacial Radiology (2009) 38, 393-400. doi: 10.1259/dmfr/40996636
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Objectives. Intrusive memories of extreme trauma can disrupt a stepwise approach to imaginal exposure. Concurrent tasks that load the visuospatial sketchpad (VSSP) of working memory reduce the vividness of recalled images. This study tested whether relief of distress from competing VSSP tasks during imaginal exposure is at the cost of impaired desensitization. Design. This study examined repeated exposure to emotive memories using 18 unselected undergraduates and a within-subjects design with three exposure conditions (Eye Movement, Visual Noise, Exposure Alone) in random, counterbalanced order. Method. At baseline, participants recalled positive and negative experiences, and rated the vividness and emotiveness of each image. A different positive and negative recollection was then used for each condition. Vividness and emotiveness were rated after each of eight exposure trials. At a post-exposure session 1 week later, participants rated each image without any concurrent task. Results. Consistent with previous research, vividness and distress during imaging were lower during Eye Movements than in Exposure Alone, with passive visual interference giving intermediate results. A reduction in emotional responses from Baseline to Post was of similar size for the three conditions. Conclusion. Visuospatial tasks may offer a temporary response aid for imaginal exposure without affecting desensitization.