322 research outputs found

    Interactive Flag Identification

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    We propose an interactive system for identifying flags in photos taken from natural scenes. The system is interactive in two respects. First, because segmentation can be a difficult problem, users are asked to crop the flag portion from a photo. Second, the user makes the final decision by selecting one of the top choices obtained from the machine classification system. The proposed system utilizes a color-based image retrieval technique. For experimental purposes a large number of flag images are synthetically generated from a small number of original ones in order to increase the reference image database. A nearest neighbor classifier produces a sorted list of candidate choices. Recognition accuracy of these choices varies from 82% to 93% depending on whether the correct flag is among the first 8 or 18 top choices, respectively, from a set of 186 flags

    Analyzing Shape Context Using the Hamiltonian Cycle

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    Shape matching plays important roles in many fields such as object recognition, image retrieval,etc. Belongie, et.al.recently proposed a novel shape matching algorithm utilizing the shape context as a shape descriptor and the magnitude of the aligning two shape contexts as a distance measure. It was claimed to be an information rich descriptor that is invariant to translation, scale and rotation. We examine the limitation of the algorithm using graph theory and present several geometrically different shapes that are considered identical by the shape context algorithm. Theoretical contributions pertain to linking shape context and the Hamiltonian cycle.

    Developing a keystroke biometric system for continual authentication of computer users,”

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    Abstract-Data windows of keyboard input are analyzed to continually authenticate computer users and verify that they are the authorized ones. Because the focus is on fast intruder detection, the authentication process operates on short bursts of roughly a minute of keystroke input, while the training process can be extensive and use hours of input. The biometric system consists of components for data capture, feature extraction, authentication classification, and receiveroperating-characteristic curve generation. Using keystroke data from 120 users, system performance was obtained as a function of two independent variables: the user population size and the number of keystrokes per sample. For each population size, the performance increased (and the equal error rate decreased) roughly logarithmically as the number of keystrokes per sample was increased. The best closed-system performance results of 99 percent on 14 participants and 96 percent on 30 participants indicate the potential of this approach

    Elastic pneumatic tourniquet cuff can reduce postoperative thigh pain after total knee arthroplasty: a prospective randomized trial

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    Abstract Background Tourniquet use is associated with complications such as thigh pain, skin problems, and deep vein thrombosis (DVT). This prospective study aimed to evaluate the efficacy and safety of the pneumatic tourniquet system using an elastic cuff and limb occlusion pressure (LOP) in total knee arthroplasty (TKA). The hypothesis of this study was that an elastic cuff tourniquet would result in less postoperative thigh pain after TKA. Methods This prospective randomized controlled trial involved a total of 98 patients who underwent primary TKA. They were randomized into two groups: tourniquet system using an elastic cuff and LOP group (Group E) and tourniquet system using a conventional-cuff and LOP group (Group C). Outcomes including postoperative thigh pain assessed using a visual analog scale (VAS), serum muscle enzymes, recommended tourniquet pressure (RTP), bloodlessness of surgical field, surgical time, incidence of DVT, and the frequency of rescue analgesic use after surgery, were compared between groups. Results Patients in Group E experienced significantly less thigh pain compared to those in Group C on postoperative day 4 (P = 0.01) and day 7 (P = 0.04). The difference between RTP and systolic blood pressure was significantly lower in Group E (P = 0.045). One case of thigh DVT was found in Group E, while no such cases were found in Group C. One and two cases of poor bloodless surgical fields were observed in Group E and Group C, respectively. There was no significant difference in surgical time, levels of serum muscle enzymes, and the frequency of rescue analgesic use between the two groups. Conclusions The pneumatic tourniquet system using an elastic cuff and LOP reduced early postoperative thigh pain more effectively than did the tourniquet system using a conventional cuff and LOP. Trial registration # KCT0003149 . Registered August 17, 2018 - Retrospectively registered

    Electronic structures of hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films

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    We investigated the electronic structure of multiferroic hexagonal RMnO3 (R = Gd, Tb, Dy, and Ho) thin films using both optical spectroscopy and first-principles calculations. Using artificially stabilized hexagonal RMnO3, we extended the optical spectroscopic studies on the hexagonal multiferroic manganite system. We observed two optical transitions located near 1.7 eV and 2.3 eV, in addition to the predominant absorption above 5 eV. With the help of first-principles calculations, we attribute the low-lying optical absorption peaks to inter-site transitions from the oxygen states hybridized strongly with different Mn orbital symmetries to the Mn 3d3z2-r2 state. As the ionic radius of the rare earth ion increased, the lowest peak showed a systematic increase in its peak position. We explained this systematic change in terms of a flattening of the MnO5 triangular bipyramid

    Interactive Visual System

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    Mobile computing devices are being endowed with ever-increasing functionality. To demonstrate the augmentation of human cognition in an interactive visual recognition task, we reengineered a PC-based system called CAVIAR (Computer Assisted Visual Interactive System) for a handheld computer with camera system. The resulting Interactive Visual System exploits the pattern recognition capabilities of humans and the computational power of a computer to identify flowers based on features that are interactively extracted from an image and submitted for comparison to a species database. While IVS has similar functionality to that of CAVIAR, because it runs on a handheld computer, it offers complete portability for use in the field. We find that the handheld IVS and PC-based CAVIAR systems outperform humans alone both on speed and accuracy and machines alone on accuracy

    Automatic segmentation of multiple cardiovascular structures from cardiac computed tomography angiography images using deep learning.

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    OBJECTIVES:To develop, demonstrate and evaluate an automated deep learning method for multiple cardiovascular structure segmentation. BACKGROUND:Segmentation of cardiovascular images is resource-intensive. We design an automated deep learning method for the segmentation of multiple structures from Coronary Computed Tomography Angiography (CCTA) images. METHODS:Images from a multicenter registry of patients that underwent clinically-indicated CCTA were used. The proximal ascending and descending aorta (PAA, DA), superior and inferior vena cavae (SVC, IVC), pulmonary artery (PA), coronary sinus (CS), right ventricular wall (RVW) and left atrial wall (LAW) were annotated as ground truth. The U-net-derived deep learning model was trained, validated and tested in a 70:20:10 split. RESULTS:The dataset comprised 206 patients, with 5.130 billion pixels. Mean age was 59.9 ± 9.4 yrs., and was 42.7% female. An overall median Dice score of 0.820 (0.782, 0.843) was achieved. Median Dice scores for PAA, DA, SVC, IVC, PA, CS, RVW and LAW were 0.969 (0.979, 0.988), 0.953 (0.955, 0.983), 0.937 (0.934, 0.965), 0.903 (0.897, 0.948), 0.775 (0.724, 0.925), 0.720 (0.642, 0.809), 0.685 (0.631, 0.761) and 0.625 (0.596, 0.749) respectively. Apart from the CS, there were no significant differences in performance between sexes or age groups. CONCLUSIONS:An automated deep learning model demonstrated segmentation of multiple cardiovascular structures from CCTA images with reasonable overall accuracy when evaluated on a pixel level

    Two-Dimensional Nature of Four-Layer Superconductors by Inequivalent Hole Distribution

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    The magnetization of the four-layer superconductor CuBa_{2}Ca_{3}Cu_4O_{12-\delta} with T_c\simeq117 K is presented. The high-field magnetization around T_c(H) follows the exact two-dimensional scaling function given by Te\v{s}anovi\'{c} and Andreev. This feature is contrary to the inference that the interlayer coupling becomes strong if the number of CuO_2 planes in a unit cell increases. Also, the fluctuation-induced susceptibility in the low-field region was analyzed by using the modified Lawrence-Doniach model. The effective number of independently fluctuating CuO_2 layers per unit cell, g_{\rm eff}, turned out to be \simeq 2 rather than 4, which indicated that two among the four CuO_2 layers were in states far from their optimal doping levels. This result could explain why CuBa_{2}Ca_{3}Cu_4O_{12-\delta} shows two-dimensional behavior.Comment: 5 pages and 4 figure

    Association between colony-stimulating factor 1 receptor gene polymorphisms and asthma risk

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    Colony-stimulating factor 1 receptor (CSF1R) is expressed in monocytes/macrophages and dendritic cells. These cells play important roles in the innate immune response, which is regarded as an important aspect of asthma development. Genetic alterations in the CSF1R gene may contribute to the development of asthma. We investigated whether CSF1R gene polymorphisms were associated with the risk of asthma. Through direct DNA sequencing of the CSF1R gene, we identified 28 single nucleotide polymorphisms (SNPs) and genotyped them in 303 normal controls and 498 asthmatic patients. Expression of CSF1R protein and mRNA were measured on CD14-positive monocytes and neutrophils in peripheral blood of asthmatic patients using flow cytometry and real-time PCR. Among the 28 polymorphisms, two intronic polymorphism (+20511C>T and +22693T>C) were associated with the risk of asthma by logistic regression analysis. The frequencies of the minor allele at CSF1R +20511C>T and +22693T>C were higher in asthmatic subjects than in normal controls (4.6 vs. 7.7%, p = 0.001 in co-dominant and dominant models; 16.4 vs. 25.8%, p = 0.0006 in a recessive model). CSF1R mRNA levels in neutrophils of the asthmatic patients having the +22693CC allele were higher than in those having the +22693TT allele (p = 0.026). Asthmatic patients with the +22693CC allele also showed significantly higher CSF1R expression on CD14-positive monocytes and neutrophils than did those with the +22693TT allele (p = 0.045 and p = 0.044). The +20511C>T SNP had no association with CSF1R mRNA or protein expression. In conclusion, the minor allele at CSF1R +22693T>C may have a susceptibility effect in the development of asthma, via increased CSF1R protein and mRNA expression in inflammatory cells
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