Visual-LiDAR Odometry and Mapping with Monocular Scale Correction and Motion Compensation

This paper presents a novel visual-LiDAR odometry and mapping method with low-drift characteristics. The proposed method is based on two popular approaches, ORB-SLAM and A-LOAM, with monocular scale correction and visual-assisted LiDAR motion compensation modifications. The scale corrector calculates the proportion between the depth of image keypoints recovered by triangulation and that provided by LiDAR, using an outlier rejection process for accuracy improvement. Concerning LiDAR motion compensation, the visual odometry approach gives the initial guesses of LiDAR motions for better performance. This methodology is not only applicable to high-resolution LiDAR but can also adapt to low-resolution LiDAR. To evaluate the proposed SLAM system's robustness and accuracy, we conducted experiments on the KITTI Odometry and S3E datasets. Experimental results illustrate that our method significantly outperforms standalone ORB-SLAM2 and A-LOAM. Furthermore, regarding the accuracy of visual odometry with scale correction, our method performs similarly to the stereo-mode ORB-SLAM2.Comment: 7 pages, 7 figures, 31 reference

Evaluation of the Oregon bicycle helmet use law on bicycle helmet usage and bicycle-related head injuries

The objectives of this study were to 1) assess the effectiveness of the law in increasing helmet use and compare methods of measuring helmet use, and 2) determine the impact of the law on bicycle-related head injury and fatalities. To measure changes in helmet use by children under 16 years of age, we conducted three statewide pre- and post-law surveys: direct observations, telephone surveys of parents, and classroom surveys of students. We identified bicycle-related head injury cases during July 1989 -, June 1995 through the Oregon Trauma Registry and Vital Statistical Department. Time series analysis was employed to determine if the secular trend and intervention were actual effects rather than random noise. Observed helmet use increased from 24.5% pre-law to 49.3% post-law (P<0.01). Classroom survey self-reported "always" use of helmets increased from 14.7% to 39.4% afterwards (P₍₂₎<0.01). Younger girls were more likely to comply the law. Helmet ownership increased from 5 1.5% pre-law to 75.5% afterwards on the student surveys (P₍₂₎<0.01) and from 67.4% to 83.9% on the parent surveys (P₍₂₎<0.01). The increase in helmet ownership was greater among children with low household-income. The results obtained from classroom surveys and direct observations were correlated (r=0.76, P<0.0l). The majority of students (87.8%) and parents (95.4%) knew about the Oregon bicycle helmet law, but only half of the students thought the law was a "good idea." One year after the law was effective, the incidence rate of statewide bicycle-related head injury decreased from 3.9 per 100,000 person-years pre-law to 2.9 per 100,000 person-years (P₍₂₎<0.001). The decrease was most profound in children under 16 years of age. For children under 16 years of age, the decreasing trend of bicycle-related head injuries appeared to mirror the increasing trend of helmet usage. We conclude that 1) the law increased helmet use; 2) the law helped reduce the bicycle-related severe head injuries; and 3) although use estimates differ, all helmet surveys showed similar degrees of pre- and post-law change. Our results suggest that the laws may be an effective approach to increase helmet use and reduce head injury in other states

Monolayer Excitonic Laser

Recently, two-dimensional (2D) materials have opened a new paradigm for fundamental physics explorations and device applications. Unlike gapless graphene, monolayer transition metal dichalcogenide (TMDC) has new optical functionalities for next generation ultra-compact electronic and opto-electronic devices. When TMDC crystals are thinned down to monolayers, they undergo an indirect to direct bandgap transition, making it an outstanding 2D semiconductor. Unique electron valley degree of freedom, strong light matter interactions and excitonic effects were observed. Enhancement of spontaneous emission has been reported on TMDC monolayers integrated with photonic crystal and distributed Bragg reflector microcavities. However, the coherent light emission from 2D monolayer TMDC has not been demonstrated, mainly due to that an atomic membrane has limited material gain volume and is lack of optical mode confinement. Here, we report the first realization of 2D excitonic laser by embedding monolayer tungsten disulfide (WS2) in a microdisk resonator. Using a whispering gallery mode (WGM) resonator with a high quality factor and optical confinement, we observed bright excitonic lasing in visible wavelength. The Si3N4/WS2/HSQ sandwich configuration provides a strong feedback and mode overlap with monolayer gain. This demonstration of 2D excitonic laser marks a major step towards 2D on-chip optoelectronics for high performance optical communication and computing applications.Comment: 15 pages, 4 figure

Immigrant assimilation and BMI and waist size: A longitudinal examination among hispanic and chinese participants in the multi‐ethnic study of atherosclerosis

Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/99611/1/oby20104.pd

Identification of Heart Failure Events in Medicare Claims: The Atherosclerosis Risk in Communities (ARIC) Study

We examined the accuracy of CMS Medicare HF diagnostic codes in the identification of acute decompensated and chronic stable HF (ADHF and CSHF)

MMP2 genetic variation is associated with measures of fibrous cap thickness: The Atherosclerosis Risk in Communities Carotid MRI Study

Objective- Genetic variation in matrix metalloproteinase (MMP) promoter regions alters the transcriptional activity of MMPs and has been consistently associated with CHD, presumably through plaque degradation and remodeling. We examined the association of MMP promoter variation with multiple plaque characteristics measured by gadolinium-enhanced MRI among 1,700 participants in the Atherosclerosis Risk in Communities (ARIC) Carotid MRI Study. Methods—For the analyses presented here, 1,700 participants of the biracial ARIC Carotid MRI Study (~1,000 participants with thick carotid artery walls and ~700 randomly sampled participants) were evaluated for associations of MMP genetic variation with multiple plaque characteristics, including carotid artery wall thickness, lipid core and fibrous cap measures. MRI studies were performed on a 1.5T scanner equipped with a bilateral 4-element phased array carotid coil. Results—Fifty-one percent of the participants were female, 77% white, 23% African American, and the mean age was 70 years. MMP2 C-1306T variant genotypes (CT+TT) were significantly associated with higher cap thickness measures, but not with wall thickness or lipid core measures. Individuals with the CC genotype had approximately 0.1 mm thinner cap thickness compared to those carrying a T allele (p=0.02). Conclusion—Genetic variation within the MMP2 promoter region was associated with cap thickness and therefore may influence the role of MMP2 in plaque vulnerability

Socioeconomic position, race/ethnicity and inflammation in the Multi-Ethnic Study of Atherosclerosis

Background— Low socioeconomic position is known to be associated with cardiovascular events and atherosclerosis. Reasons for these associations remain a topic of research. Inflammation could be an important mediating mechanism linking socioeconomic position to cardiovascular risk. Methods and Results— This cross-sectional study used data from the baseline examination of the Multi-Ethnic Study of Atherosclerosis (MESA), a study of 6814 men and women 45 to 84 years of age. Race- and ethnicity-stratified regression analyses were used to estimate associations of household income and education with C-reactive protein and interleukin-6 before and after adjustment for infection and medication use, psychosocial factors, behaviors, adiposity, and diabetes mellitus. Low income was associated with higher concentrations of interleukin-6 in all race/ethnic groups. Percent differences associated with 1-SD–lower income were 9% (95% confidence interval [CI], 7 to 11), 6% (95% CI, 1 to 10), 8% (95% CI, 4 to 11), and 8% (95% CI, 3 to 13) for whites, Chinese, blacks, and Hispanics. Low levels of education were associated with higher levels of interleukin-6 only among whites and blacks (percent difference in interleukin-6 associated with 1-SD–lower education: 9% [95% CI, 6 to 12] among Whites, and 7% [95% CI, 3 to 10] among blacks). Similar patterns were observed for C-reactive protein. Adiposity was the single most important factor explaining socioeconomic position associations, especially among blacks and whites. A smaller effect was seen for psychosocial factors and behaviors in all race groups. Conclusions— Both household income and education are associated with inflammation, but associations vary across race/ethnic groups. Associations likely result from socioeconomic position patterning of adiposity and other factorshttp://deepblue.lib.umich.edu/bitstream/2027.42/57887/1/Socioeconomic position Race Ethnicity and Inflammation in the Multi-Ethnic Study of Atherosclerosis.pd

Trajectories of neighborhood poverty and associations with subclinical atherosclerosis and associated risk factors: the multi-ethnic study of atherosclerosis

The authors used data from the Multi-Ethnic Study of Atherosclerosis and latent trajectory class modeling to determine patterns of neighborhood poverty over 20 years (1980-2000 residential history questionnaires were geocoded and linked to US Census data). Using these patterns, the authors examined 1) whether trajectories of neighborhood poverty were associated with differences in the amount of subclinical atherosclerosis (common carotid intimal-media thickness) and 2) associated risk factors (body mass index, hypertension, diabetes, current smoking) at baseline (January 2000-August 2002). The authors found evidence of 5 stable trajectory groups with differing levels of neighborhood poverty ( approximately 6%, 12%, 20%, 30%, and 45%) and 1 group with 29% poverty in 1980 and approximately 11% in 2000. Mostly for women, higher cumulative neighborhood poverty was generally significantly associated with worse cardiovascular outcomes. Trends generally persisted after adjustment for adulthood socioeconomic position and race/ethnicity, although they were no longer statistically significant. Among women who had moved during the 20 years, the long-term measure had stronger associations with outcomes (except smoking) than a single, contemporaneous measure. Results indicate that cumulative 20-year exposure to neighborhood poverty is associated with greater cardiovascular risk for women. In residentially mobile populations, single-point-in-time measures underestimate long-term effects.http://deepblue.lib.umich.edu/bitstream/2027.42/78374/1/MurrayDiezRoux2010_AJE.pd

Trends from 1987 to 2004 in sudden death due to coronary heart disease: The Atherosclerosis Risk in Communities (ARIC) study

Few data are available on the secular changes in sudden coronary heart disease (CHD) death in U.S. communities