2,244 research outputs found

    Surface Edge Explorer (SEE): Planning Next Best Views Directly from 3D Observations

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    Surveying 3D scenes is a common task in robotics. Systems can do so autonomously by iteratively obtaining measurements. This process of planning observations to improve the model of a scene is called Next Best View (NBV) planning. NBV planning approaches often use either volumetric (e.g., voxel grids) or surface (e.g., triangulated meshes) representations. Volumetric approaches generalise well between scenes as they do not depend on surface geometry but do not scale to high-resolution models of large scenes. Surface representations can obtain high-resolution models at any scale but often require tuning of unintuitive parameters or multiple survey stages. This paper presents a scene-model-free NBV planning approach with a density representation. The Surface Edge Explorer (SEE) uses the density of current measurements to detect and explore observed surface boundaries. This approach is shown experimentally to provide better surface coverage in lower computation time than the evaluated state-of-the-art volumetric approaches while moving equivalent distances

    Multimotion Visual Odometry (MVO): Simultaneous Estimation of Camera and Third-Party Motions

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    Estimating motion from images is a well-studied problem in computer vision and robotics. Previous work has developed techniques to estimate the motion of a moving camera in a largely static environment (e.g., visual odometry) and to segment or track motions in a dynamic scene using known camera motions (e.g., multiple object tracking). It is more challenging to estimate the unknown motion of the camera and the dynamic scene simultaneously. Most previous work requires a priori object models (e.g., tracking-by-detection), motion constraints (e.g., planar motion), or fails to estimate the full SE(3) motions of the scene (e.g., scene flow). While these approaches work well in specific application domains, they are not generalizable to unconstrained motions. This paper extends the traditional visual odometry (VO) pipeline to estimate the full SE(3) motion of both a stereo/RGB-D camera and the dynamic scene. This multimotion visual odometry (MVO) pipeline requires no a priori knowledge of the environment or the dynamic objects. Its performance is evaluated on a real-world dynamic dataset with ground truth for all motions from a motion capture system.Comment: This updated manuscript corrects the experimental results published in the proceedings of the 2018 IEEE/RSJ International Conference on Intelligent Robots and Systems (IROS).. 8 Pages. 7 Figures. Video available at https://www.youtube.com/watch?v=84tXCJOlj0

    Relation of Patients Living Without a Partner or Spouse to Being Physically Active After Acute Coronary Syndromes (from the PULSE Accelerometry Substudy)

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    Living alone is associated with adverse outcomes after acute coronary syndromes (ACS). One potential mediator of the relation between partner status and outcomes after ACS is physical activity. To evaluate the association of partner status with physical activity after ACS, data from 107 participants enrolled in the Prescription Use, Lifestyle, and Stress Evaluation (PULSE) study, a prospective observational study of post-ACS patients, were analyzed. Accelerometers were used to measure physical activity after hospital discharge. The primary outcome measure was a maximum 10 hours of daytime activity 1 month after discharge. One month after discharge from ACS hospitalizations, participants without a partner or spouse exhibited 24.4% lower daytime activity than those with a partner or spouse (p = 0.003). After controlling for age, gender, body mass index, Charlson co-morbidity index, and traditional psychosocial and clinical cardiovascular correlates of post-ACS physical activity, partner status remained an independent predictor of post-ACS physical activity (20.5% lower daytime activity among those without a partner or spouse, p = 0.008). In conclusion, in this study of accelerometer-measured physical activity after an ACS hospitalization, those without a partner or spouse exhibit significantly less physical activity than those with a partner or spouse 1 month after discharge from the hospital. Low physical activity may be an important mediator of the prognosis associated with partner status after ACS

    A Study on Developer Perception of Transformation Languages for Refactoring

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    Although there is much research advancing state-of-art of program transformation tools, their application in industry source code change problems has not yet been gauged. In this context, the purpose of this paper is to better understand developer familiarity and comfort with these languages by conducting a survey. It poses, and answers, four research questions to understand how frequently source code transformation languages are applied to refactoring tasks, how well-known these languages are in industry, what developers think are obstacles to adoption, and what developer refactoring habits tell us about their current use, or underuse, of transformation languages. The results show that while source code transformation languages can fill a needed niche in refactoring, research must motivate their application. We provide explanations and insights based on data, aimed at the program transformation and refactoring communities, with a goal to motivate future research and ultimately improve industry adoption of transformation languages for refactoring tasks

    Post-Traumatic Stress Disorder (PTSD) Symptoms Predict Delay to Hospital in Patients with Acute Coronary Syndrome

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    Background: Increased delay to hospital presentation with acute coronary syndrome (ACS) is associated with poor outcomes. While demographic factors associated with this delay have been well described, scarce data are available on the role of modifiable factors, such as psychosocial disorders, on pre-hospital delay. Patients with symptoms of post-traumatic stress disorder (PTSD) often avoid stressful situations and may delay presenting for care when they experience cardiac symptoms. It is unknown, however, whether PTSD symptoms negatively impact the time to presentation during an ACS. Methods: We assessed the relationship between PTSD symptoms and pre-hospital delay in 241 adults with an ACS in the ongoing Prescription Use, Lifestyle, Stress Evaluation (PULSE) study. Results: Overall, 66 % of patients were male; 40 % were Hispanic or Latino. The mean age was 61.9611.6 years old. PTSD symptoms were present in 17.8 % of patients. Pre-hospital delay was longer for patients with PTSD symptoms compared to those without [geometric mean: 25.8 hours (95 % CI 13.8 – 44.8) vs. 10.7 hours (95 % CI 8.3 – 13.8)]; P = 0.005. After multivariable adjustment for age, sex, ethnicity, depression, left ventricular ejection fraction and history of myocardial infarction, the mean pre-hospital delay was 173 % (95 % CI: 36 % –450%) longer for patients with versus without PTSD symptoms. Conclusion: Among patients presenting with an ACS, PTSD symptoms were independently associated with longer prehospita

    Thermal Tolerances of the Spotted-Wing Drosophila Drosophila suzukii (Diptera: Drosophilidae)

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    The spotted-wing drosophila (Drosophila suzukii Matsumura) is an invasive species of Asian origin that is now widely distributed in North America and Europe. Because of the female’s serrated ovipositor, eggs are laid in preharvest fruit, causing large economic losses in cultivated berries and stone fruit. Modeling D. suzukii population dynamics and potential distribution will require information on its thermal tolerance. Large summer populations have been found in regions with severe winter conditions, though little is known about responses to prolonged low-temperature exposure. We used controlled chambers to examine D. suzukii fecundity, development rate, and mortality across a range of temperatures encompassing the upper and lower thresholds (5–35°C). Optimal temperatures ( Topt ) were found to be 28.2°C for the development of the egg-to-adult stage, and 22.9°C for reproductive output. No adult eclosion occurred below 8.1°C ( Tlower ) or above 30.9°C ( Tupper ). We also investigated survival outcomes following prolonged (42-d) low-temperature exposure to a simulated cold winter (−5, −3, −1, 1, 3, and 5°C). Adult survival was dependent on temperature, with a mean LT50 of 4.9°C. There were no effects of sex, mating status, geographic strain, and photoperiod preexposure on overwintering survival. Thirty-eight percent of females that were mated prior, but not after, prolonged low-temperature exposure produced viable offspring, suggesting that this species may undergo sperm storage. This study provides data on the thermal tolerances of D. suzukii , which can be used for models of D. suzukii population dynamics, degree-day, and distribution models

    Observed Hostility and the Risk of Incident Ischemic Heart Disease: A Prospective Population Study From the 1995 Canadian Nova Scotia Health Survey

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    Objectives The aim of this study was to examine the relation between hostility and incident ischemic heart disease (IHD) and to determine whether observed hostility is superior to patient-reported hostility for the prediction of IHD in a large, prospective observational study. Background Some studies have found that hostile patients have an increased risk of incident IHD. However, no studies have compared methods of hostility assessment or considered important psychosocial and cardiovascular risk factors as confounders. Furthermore, it is unknown whether all expressions of hostility carry equal risk or whether certain manifestations are more cardiotoxic. Methods We assessed the independent relationship between baseline observed hostility and 10-year incident IHD in 1,749 adults of the population-based Canadian Nova Scotia Health Survey. Results There were 149 (8.5%) incident IHD events (140 nonfatal, 9 fatal) during the 15,295 person-years of observation (9.74 events/1,000 person-years). Participants with any observed hostility had a greater risk of incident IHD than those without (p = 0.02); no such relation was found for patient-reported hostility. Those with any observed hostility had a significantly greater risk of incident IHD (hazard ratio: 2.06, 95% confidence interval: 1.04 to 4.08, p = 0.04), after adjusting for cardiovascular (age, sex, Framingham Risk Score) and psychosocial (depression, positive affect, patient-reported hostility, and anger) risk factors. Conclusions The presence of any observed hostility at baseline was associated with a 2-fold increased risk of incident IHD over 10 years of follow-up. Compared with patient-reported measures, observed hostility is a superior predictor of IHD
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