1,044 research outputs found
Protection of Overwintering Aphid Parasitoid, Lysiphlebia japonica [Hym.: Aphidiidae]
Tonghua County is located in the Changbaishan mountain area where there are about 130 days yearly with average temperature below 0ºC and the lowest temperature can reach - 35ºC. To understand the natural survival of overwintering Lysiphlebia japonica, we observed the survival of overwintering parasitoids and carried out overwintering protection experiments.Originating text in Chinese.Citation: Gao, Junfeng, Yu, Kai. (1991). Protection of Overwintering Aphid Parasitoid, Lysiphlebia japonica [Hym.: Aphidiidae]. Chinese Journal of Biological Control, 7(4), 188-189
SemanticLoop: loop closure with 3D semantic graph matching
Loop closure can effectively correct the accumulated error in robot
localization, which plays a critical role in the long-term navigation of the
robot. Traditional appearance-based methods rely on local features and are
prone to failure in ambiguous environments. On the other hand, object
recognition can infer objects' category, pose, and extent. These objects can
serve as stable semantic landmarks for viewpoint-independent and non-ambiguous
loop closure. However, there is a critical object-level data association
problem due to the lack of efficient and robust algorithms.
We introduce a novel object-level data association algorithm, which
incorporates IoU, instance-level embedding, and detection uncertainty,
formulated as a linear assignment problem. Then, we model the objects as TSDF
volumes and represent the environment as a 3D graph with semantics and
topology. Next, we propose a graph matching-based loop detection based on the
reconstructed 3D semantic graphs and correct the accumulated error by aligning
the matched objects. Finally, we refine the object poses and camera trajectory
in an object-level pose graph optimization.
Experimental results show that the proposed object-level data association
method significantly outperforms the commonly used nearest-neighbor method in
accuracy. Our graph matching-based loop closure is more robust to environmental
appearance changes than existing appearance-based methods
Self-protected nanoscale thermometry based on spin defects in silicon carbide
Quantum sensors with solid state electron spins have attracted considerable
interest due to their nanoscale spatial resolution.A critical requirement is to
suppress the environment noise of the solid state spin sensor.Here we
demonstrate a nanoscale thermometer based on silicon carbide (SiC) electron
spins.We experimentally demonstrate that the performance of the spin sensor is
robust against dephasing due to a self protected machenism. The SiC thermometry
may provide a promising platform for sensing in a noisy environment ,e.g.
biological system sensing
An X-ray View of Two Infrared Dark Clouds G034.43+00.24 and G035.39-00.33
We present a high spatial resolution Chandra X-ray study of two Infrared Dark
Clouds (IRDCs), G034.43+00.24 and G035.39-00.33, which are expected to be in
the early phases of star cluster formation. We detect 112 and 209 valid X-ray
point sources towards G034.43+00.24 and G035.39-00.33, respectively. We
cross-match the X-ray point sources with 2MASS, GLIMPSE and WISE catalogs and
find 53% and 59% of the X-ray sources in G034.43+00.24 and in G035.39-00.33
have corresponding infrared counterparts, respectively. These sources are
probable members of young massive clusters in formation, and using stellar
isochrones we estimate that a population of 1--2 Myr old, intermediate to high
mass young stellar objects (YSOs) exist in both IRDCs. Two and ten Class II
counterparts to X-ray sources were identified in G034.43+00.24 and in
G035.39-00.33, respectively, which are located in or near dark filaments. The
X-ray Luminosity Function (XLF) of G035.39-00.33 implies that the total mass
consists of up to of stars, using the XLF of the
well-studied Orion Nebula Cluster as calibrator. This corresponds to a star
formation efficiency of at most 5%, indicating the system is still very much
gas dominated and in an early stage of the star formation process. The
population of G034.43+00.24 is less well determined due to the lower
sensitivity of its observations.Comment: Accepted for publication in ApJ. 18 pages, 5 figures, 8 tables. Full
tables will be available online as machine readable table
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