2,203 research outputs found

    Fast eigenspace decomposition of correlated images

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    Includes bibliographical references.We present a computationally efficient algorithm for the eigenspace decomposition of correlated images. Our approach is motivated by the fact that for a planar rotation of a two-dimensional (2-D) image, analytical expressions can be given for the eigendecomposition, based on the theory of circulant matrices. These analytical expressions turn out to be good first approximations of the eigendecomposition, even for three-dimensional (3-D) objects rotated about a single axis. In addition, the theory of circulant matrices yields good approximations to the eigendecomposition for images that result when objects are translated and scaled. We use these observations to automatically determine the dimension of the subspace required to represent an image with a guaranteed user-specified accuracy, as well as to quickly compute a basis for the subspace. Examples show that the algorithm performs very well on a number of test cases ranging from images of 3-D objects rotated about a single axis to arbitrary video sequences.This work was supported by the Sze Tsao Chang Memorial Engineering Fund, the National Imagery and Mapping Agency under Contract NMA201-00-1-1003, and by the Office of Naval Research under Contract N00014-97-1-0640

    Visual Object Recognition and Tracking of Tools

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    A method has been created to automatically build an algorithm off-line, using computer-aided design (CAD) models, and to apply this at runtime. The object type is discriminated, and the position and orientation are identified. This system can work with a single image and can provide improved performance using multiple images provided from videos. The spatial processing unit uses three stages: (1) segmentation; (2) initial type, pose, and geometry (ITPG) estimation; and (3) refined type, pose, and geometry (RTPG) calculation. The image segmentation module files all the tools in an image and isolates them from the background. For this, the system uses edge-detection and thresholding to find the pixels that are part of a tool. After the pixels are identified, nearby pixels are grouped into blobs. These blobs represent the potential tools in the image and are the product of the segmentation algorithm. The second module uses matched filtering (or template matching). This approach is used for condensing synthetic images using an image subspace that captures key information. Three degrees of orientation, three degrees of position, and any number of degrees of freedom in geometry change are included. To do this, a template-matching framework is applied. This framework uses an off-line system for calculating template images, measurement images, and the measurements of the template images. These results are used online to match segmented tools against the templates. The final module is the RTPG processor. Its role is to find the exact states of the tools given initial conditions provided by the ITPG module. The requirement that the initial conditions exist allows this module to make use of a local search (whereas the ITPG module had global scope). To perform the local search, 3D model matching is used, where a synthetic image of the object is created and compared to the sensed data. The availability of low-cost PC graphics hardware allows rapid creation of synthetic images. In this approach, a function of orientation, distance, and articulation is defined as a metric on the difference between the captured image and a synthetic image with an object in the given orientation, distance, and articulation. The synthetic image is created using a model that is looked up in an object-model database. A composable software architecture is used for implementation. Video is first preprocessed to remove sensor anomalies (like dead pixels), and then is processed sequentially by a prioritized list of tracker-identifiers

    Visual object recognition and tracking

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    This invention describes a method for identifying and tracking an object from two-dimensional data pictorially representing said object by an object-tracking system through processing said two-dimensional data using at least one tracker-identifier belonging to the object-tracking system for providing an output signal containing: a) a type of the object, and/or b) a position or an orientation of the object in three-dimensions, and/or c) an articulation or a shape change of said object in said three dimensions

    Quadtree-based eigendecomposition for pose estimation in the presence of occlusion and background clutter

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    Includes bibliographical references (pages 29-30).Eigendecomposition-based techniques are popular for a number of computer vision problems, e.g., object and pose estimation, because they are purely appearance based and they require few on-line computations. Unfortunately, they also typically require an unobstructed view of the object whose pose is being detected. The presence of occlusion and background clutter precludes the use of the normalizations that are typically applied and significantly alters the appearance of the object under detection. This work presents an algorithm that is based on applying eigendecomposition to a quadtree representation of the image dataset used to describe the appearance of an object. This allows decisions concerning the pose of an object to be based on only those portions of the image in which the algorithm has determined that the object is not occluded. The accuracy and computational efficiency of the proposed approach is evaluated on 16 different objects with up to 50% of the object being occluded and on images of ships in a dockyard

    Sarcoma of the Larynx: Treatment Results and Literature Review

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    BackgroundSarcomas of the larynx are rare neoplasms that constitute less than 1% of laryngeal malignancies. A Medline search found no large series focusing on laryngeal sarcomas. We reviewed the cases of laryngeal sarcomas treated in our cancer center and compared our experiences and treatment results with those from other centers.MethodsA retrospective review of 10 patients with laryngeal sarcoma treated in our institute between 1980 and 2000 was done to identify tumor characteristics, therapeutic modalities, and treatment outcomes.ResultsThe patients showed a male predominance (9/10) and presented 8 types of pathology. Nine patients underwent surgery, including 2 total laryngectomy, 4 partial laryngectomy, and 3 endoscopic laser cordectomy. During a median follow-up of 92 months, the 5-year overall survival and disease-specific survival were 76% and 90%, respectively. Two patients developed recurrence, including 1 local recurrence and 1 distant metastasis.ConclusionSurgical intervention was the first choice in the treatment of laryngeal sarcomas. The prognosis is relatively good when compared with sarcoma originating from other anatomic sites

    Otocephaly

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    Otocephaly is a rare lethal syndrome of microstomia, aglossia, agnathia, and synotia. This male infant was born to a 19-year-old, gravida 1, para 0, woman who received routine prenatal check-up. Polyhydramnios, low-lying ears, and proboscis were noted by sonography at 29 weeks of gestation. Amniocentesis showed a normal karyotype of 46, XY. Premature rupture of membranes and preterm labor were noted at 32 weeks of gestation. A male infant was delivered preterm and died shortly after birth. The infant showed midline proboscis and absence of mandible. The simple, soft ears were extremely low-set and were near the midline of the neck. Otocephaly is regarded as the most severe form of first arch anomalies. Prenatal diagnosis should be dependent on ultrasound analysis. In the face of polyhydramnios, otocephaly is one of the possible fetal anomalies

    The SGLT2 Inhibitor Empagliflozin Might Be a New Approach for the Prevention of Acute Kidney Injury

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    Three randomized control trials (Canagliflozin Cardiovascular Assessment Study, Empagliflozin Cardiovascular Outcome Event Trial in Type 2 Diabetes Mellitus Patients [EMPA-REG OUTCOME], and Dapagliflozin Effect on Cardiovascular Events-Thrombolysis in Myocardial Infarction 58 [DECLARE-TIMI 58]) showed that the sodium-glucose co-transporter 2 (SGLT2) inhibitors, originally developed as glucose-lowering drugs, are associated with a lower rate of adverse renal outcomes, such as need for renal replacement therapy, doubling of serum creatinine, and loss of glomerular filtration rate (GFR) compared to those in placebo groups. Besides, canagliflozin and empagliflozin also showed a lower risk of progression to macroalbuminuria. The EMPA-REG OUTCOME trial and DECLARE-TIMI 58 trial also indicated that these SGLT2 inhibitors might have beneficial effects on the prevention of acute kidney injury. The United States Food and Drug Administration (FDA) warned of the risk of acute kidney injury for canagliflozin and dapagliflozin. We compared canagliflozin, empagliflozin, and dapagliflozin with respect to chemical structure and pharmacological properties, to explain the observed differences in preventing acute kidney injury, and put forward the hypotheses of the potential mechanisms of different effects of SGLT2 inhibitors on acute kidney injury. Given the raising clinical use of SGLT2 inhibitors, our review should stimulate further basic science and clinical studies in order to definitively understand the role of SGLT2 inhibitors in acute kidney injury. A weakness of the clinical data obtained so far is the fact that the statements concerning acute kidney injury are just based on safety data – mainly creatine measurements. However, given the mode of action of SGLT2 blockers, initiation of a therapy with a SGLT2 blocker will cause an increase of creatine because of its effects on the tubuloglomerular feedback mechanisms/glomerular hemodynamics like RAAS blocking agents do. To really understand the potential effects of SGLT2 inhibitors, we need preclinical and clinical SGLT2 inhibitor studies focusing on all aspects of acute kidney injury – not just changes in GFR biomarkers

    Systems and Methods of Coordination Control for Robot Manipulation

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    Disclosed herein are systems and methods for controlling robotic apparatus having several movable elements or segments coupled by joints. At least one of the movable elements can include one or more mobile bases, while the others can form one or more manipulators. One of the movable elements can be treated as an end effector for which a certain motion is desired. The end effector may include a tool, for example, or represent a robotic hand (or a point thereon), or one or more of the one or more mobile bases. In accordance with the systems and methods disclosed herein, movement of the manipulator and the mobile base can be controlled and coordinated to effect a desired motion for the end effector. In many cases, the motion can include simultaneously moving the manipulator and the mobile base
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