2,375 research outputs found
DS-K3DOM: 3-D Dynamic Occupancy Mapping with Kernel Inference and Dempster-Shafer Evidential Theory
Occupancy mapping has been widely utilized to represent the surroundings for
autonomous robots to perform tasks such as navigation and manipulation. While
occupancy mapping in 2-D environments has been well-studied, there have been
few approaches suitable for 3-D dynamic occupancy mapping which is essential
for aerial robots. This paper presents a novel 3-D dynamic occupancy mapping
algorithm called DSK3DOM. We first establish a Bayesian method to sequentially
update occupancy maps for a stream of measurements based on the random finite
set theory. Then, we approximate it with particles in the Dempster-Shafer
domain to enable real time computation. Moreover, the algorithm applies kernel
based inference with Dirichlet basic belief assignment to enable dense mapping
from sparse measurements. The efficacy of the proposed algorithm is
demonstrated through simulations and real experiments.Comment: 7 pages, 2 figures, submitted to ICRA 202
Two distinct red giant branch populations in the globular cluster NGC 2419 as tracers of a merger event in the Milky Way
Recent spectroscopic observations of the outer halo globular cluster (GC) NGC
2419 show that it is unique among GCs, in terms of chemical abundance patterns,
and some suggest that it was originated in the nucleus of a dwarf galaxy. Here
we show, from the Subaru narrow-band photometry employing a calcium filter,
that the red giant-branch (RGB) of this GC is split into two distinct
subpopulations. Comparison with spectroscopy has confirmed that the redder RGB
stars in the [=(Ca] index are enhanced in [Ca/H] by 0.2
dex compared to the bluer RGB stars. Our population model further indicates
that the calcium-rich second generation stars are also enhanced in helium
abundance by a large amount (Y = 0.19). Our photometry, together with
the results for other massive GCs (e.g., Cen, M22, and NGC 1851),
suggests that the discrete distribution of RGB stars in the index might be
a universal characteristic of this growing group of peculiar GCs. The planned
narrow-band calcium photometry for the Local Group dwarf galaxies would help to
establish an empirical connection between these GCs and the primordial building
blocks in the hierarchical merging paradigm of galaxy formation.Comment: 4 pages, 4 figures, 1 table, accepted for the publication in ApJ
Input of terrestrial organic matter linked to deglaciation increased mercury transport to the Svalbard fjords
Deglaciation has accelerated the transport of minerals as well as modern and ancient organic matter from land to fjord sediments in Spitsbergen, Svalbard, in the European Arctic Ocean. Consequently, such sediments may contain significant levels of total mercury (THg) bound to terrestrial organic matter. The present study compared THg contents in surface sediments from three fjord settings in Spitsbergen: Hornsund in the southern Spitsbergen, which has high annual volume of loss glacier and receives sediment from multiple tidewater glaciers, Dicksonfjorden in the central Spitsbergen, which receives sediment from glacifluvial rivers, and Wijdefjorden in the northern Spitsbergen, which receive sediments from a mixture of tidewater glaciers and glacifluvial rivers. Our results showed that the THg (52 +/- 15 ng g(-1)) bound to organic matter (OM) was the highest in the Hornsund surface sediments, where the glacier loss (0.44 km(3) yr(-1)) and organic carbon accumulation rates (9.3 similar to 49.4 g m(-2) yr(-1)) were elevated compared to other fjords. Furthermore, the delta C-13 (-27 similar to -24 parts per thousand) and delta S-34 values (-10 similar to 15 parts per thousand) of OM indicated that most of OM were originated from terrestrial sources. Thus, the temperature-driven glacial melting could release more OM originating from the meltwater or terrestrial materials, which are available for THg binding in the European Arctic fjord ecosystems.11Ysciescopu
Focal Bone Marrow Lesions: A Complication of Ultrasound Diathermy
Ultrasound diathermy is widely used for the treatment of musculoskeletal disorders and other soft tissue injuries. Its use as a therapeutic modality is believed to be safe, with very few reported complications. Here, we report two patients who developed focal bone marrow abnormalities after receiving ultrasound diathermy. Both patientsā magnetic resonance (MR) evaluations revealed linear subchondral bone lesions of the superolateral humeral head similar to those in osteonecrosis. The patientsā symptoms subsequently improved, and available follow-up MR evaluation revealed near complete resolution of bone lesions. These findings suggest that ultrasound diathermy, and its interaction with bone tissue through thermal mechanisms, can cause focal bone marrow abnormalities. Furthermore, the bone marrow abnormalities seem to be transient, resolving upon cessation of ultrasound diathermy, therefore osteonecrosis should be differentiated from this temporal lesion
Environmental Health Studies in the Korean National Industrial Complexes (EHSNIC): Focus-Group Interviews
This study investigated the social outcomes of the Environmental Health Studies of National Industrial Complex (EHSNIC), which have been conducted by the National Institute of Environmental Research (NIER) in eight National Industrial Complex Areas (NICAs) since 2003. Eighteen sessions of focus-group interviews with 85 people were conducted from October 2016 to January 2017. Interviewees were stakeholders from eight NICAs and included resident representatives, environmental nongovernment organizations, local government officials, and environmental health and safety officers from companies. Interview results were divided into six categories: EHSNIC awareness, EHSNIC outcomes, EHSNIC limitations, EHSNIC continuation, EHSNIC improvement directions, and EHSNIC results use. They were then further indexed into 23 divisions. EHSNIC awareness varied across stakeholders. A major EHSNIC outcome is that a continued result database was established, which was used as a reference for environmental improvements. EHSNIC limitations included no proper healthcare actions taken during the EHSNIC study period, a lack of EHSNIC results disclosure, a failure to reflect local specificity, and a lack of validity in the results. Regarding EHSNIC continuation, all stakeholders said EHSNIC should be conducted continuously. EHSNIC improvement directions included conducting studies tailored to each NICA, identifying correlations between pollutant exposure and disease, increasing the sample size, and performing repeated studies. Regarding EHSNIC results use, respondents wanted to use the results as a reference to relocate residents, ensure distance between NICAs and residential areas, provide healthcare support, develop local government policies, and implement firmsā environmental controls. Since EHSNIC aims to identify the health effects of NICAs on residents and take appropriate actions, it should be continued in the future. Even during the study period, it is important to take steps to preventively protect residentsā health. EHSNIC also needs to reflect each NICAās characteristics and conduct reliable research based on stakeholder participation and communication
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