34 research outputs found
Transferring CLIP's Knowledge into Zero-Shot Point Cloud Semantic Segmentation
Traditional 3D segmentation methods can only recognize a fixed range of
classes that appear in the training set, which limits their application in
real-world scenarios due to the lack of generalization ability. Large-scale
visual-language pre-trained models, such as CLIP, have shown their
generalization ability in the zero-shot 2D vision tasks, but are still unable
to be applied to 3D semantic segmentation directly. In this work, we focus on
zero-shot point cloud semantic segmentation and propose a simple yet effective
baseline to transfer the visual-linguistic knowledge implied in CLIP to point
cloud encoder at both feature and output levels. Both feature-level and
output-level alignments are conducted between 2D and 3D encoders for effective
knowledge transfer. Concretely, a Multi-granularity Cross-modal Feature
Alignment (MCFA) module is proposed to align 2D and 3D features from global
semantic and local position perspectives for feature-level alignment. For the
output level, per-pixel pseudo labels of unseen classes are extracted using the
pre-trained CLIP model as supervision for the 3D segmentation model to mimic
the behavior of the CLIP image encoder. Extensive experiments are conducted on
two popular benchmarks of point cloud segmentation. Our method outperforms
significantly previous state-of-the-art methods under zero-shot setting (+29.2%
mIoU on SemanticKITTI and 31.8% mIoU on nuScenes), and further achieves
promising results in the annotation-free point cloud semantic segmentation
setting, showing its great potential for label-efficient learning
Nanotube spin defects for omnidirectional magnetic field sensing
Optically addressable spin defects in three-dimensional (3D) crystals and
two-dimensional (2D) van der Waals (vdW) materials are revolutionizing
nanoscale quantum sensing. Spin defects in one-dimensional (1D) vdW nanotubes
will provide unique opportunities due to their small sizes in two dimensions
and absence of dangling bonds on side walls. However, optically detected
magnetic resonance of localized spin defects in a nanotube has not been
observed. Here, we report the observation of single spin color centers in boron
nitride nanotubes (BNNTs) at room temperature. Our findings suggest that these
BNNT spin defects possess a spin ground state without an intrinsic
quantization axis, leading to orientation-independent magnetic field sensing.
We harness this unique feature to observe anisotropic magnetization of a 2D
magnet in magnetic fields along orthogonal directions, a challenge for
conventional spin defects such as diamond nitrogen-vacancy centers.
Additionally, we develop a method to deterministically transfer a BNNT onto a
cantilever and use it to demonstrate scanning probe magnetometry. Further
refinement of our approach will enable atomic scale quantum sensing of magnetic
fields in any direction.Comment: 9 pages, 5 figure
Pseudo Label-Guided Data Fusion and Output Consistency for Semi-Supervised Medical Image Segmentation
Supervised learning algorithms based on Convolutional Neural Networks have
become the benchmark for medical image segmentation tasks, but their
effectiveness heavily relies on a large amount of labeled data. However,
annotating medical image datasets is a laborious and time-consuming process.
Inspired by semi-supervised algorithms that use both labeled and unlabeled data
for training, we propose the PLGDF framework, which builds upon the mean
teacher network for segmenting medical images with less annotation. We propose
a novel pseudo-label utilization scheme, which combines labeled and unlabeled
data to augment the dataset effectively. Additionally, we enforce the
consistency between different scales in the decoder module of the segmentation
network and propose a loss function suitable for evaluating the consistency.
Moreover, we incorporate a sharpening operation on the predicted results,
further enhancing the accuracy of the segmentation.
Extensive experiments on three publicly available datasets demonstrate that
the PLGDF framework can largely improve performance by incorporating the
unlabeled data. Meanwhile, our framework yields superior performance compared
to six state-of-the-art semi-supervised learning methods. The codes of this
study are available at https://github.com/ortonwang/PLGDF
Detection of groundwater storage variability based on GRACE and CABLE model in the Murray-Darling Basin
Monitoring groundwater storage is in great importance for economic and social development. In this paper, the monthly GRACE data from 2003 to 2015 is combined with the Community Atmosphere Biosphere Land Exchange (CABLE) model to estimate the variations of groundwater storage (GWS) in the Murray-Darling Basin (MDB). The results show that (1) the simulations of TWS from CABLE are more accurate than GLDAS over the MDB, and there is a higher correlation coefficient of 0.94 and a lower RMSE of 15.74 between CABLE and GRACE. (3) The spatial pattern of GWS trends shows decline trends in the southwest, east and south, and increasing trends in the north and south central (3) For the whole MDB, the average GWS has strong seasonality and shows an increasing trend with a rate of 1.19 0.41 mmyyear between 2003 and 2015
Adaptation of Abies fargesii var. faxoniana (Rehder et E.H. Wilson) Tang S Liu seedlings to high altitude in a subalpine forest in southwestern China with special reference to phloem and xylem traits
International audienceContext: Maintenance of xylem and phloem transport is particularly important for the survival and growth of trees at the treeline. How plants modify the allocation to leaf, xylem, and phloem structures to adapt to the treeline environment is an important issue.Aims: The purpose of this study was to estimate how xylem and phloem anatomy and volume as well as leaf functional traits of A. fargesii seedlings vary with elevation.MethodsWe examined elevation-related differences in a variety of phloem and xylem functional areas and hydraulic conduit diameters of A. fargesii seedlings growing at elevations between 2600 and 3200Â m in the subalpine conifer forest of southwest China.Results: Xylem area, last xylem ring area, and leaf:sapwood area significantly decreased, while xylem:leaf area, phloem:leaf area, and non-collapsed phloem:xylem area significantly increased with elevation. Principal components analysis showed that xylem area, non-collapsed phloem area, and xylem:phloem area were positively correlated with growth rates.Conclusion: Our results showed that A. fargesii tree seedlings at the treeline tend to facilitate growth and maintain functional water and sugar balance between stem and leaves by the enhancement in xylem:leaf area, phloem:leaf area, and phloem:xylem area, but not through differences in vessel lumen diameter
Quantum control and Berry phase of electron spins in rotating levitated diamonds in high vacuum
Abstract Levitated diamond particles in high vacuum with internal spin qubits have been proposed for exploring macroscopic quantum mechanics, quantum gravity, and precision measurements. The coupling between spins and particle rotation can be utilized to study quantum geometric phase, create gyroscopes and rotational matter-wave interferometers. However, previous efforts in levitated diamonds struggled with vacuum level or spin state readouts. To address these gaps, we fabricate an integrated surface ion trap with multiple stabilization electrodes. This facilitates on-chip levitation and, for the first time, optically detected magnetic resonance measurements of a nanodiamond levitated in high vacuum. The internal temperature of our levitated nanodiamond remains moderate at pressures below 10−5 Torr. We have driven a nanodiamond to rotate up to 20 MHz (1.2 × 109 rpm), surpassing typical nitrogen-vacancy (NV) center electron spin dephasing rates. Using these NV spins, we observe the effect of the Berry phase arising from particle rotation. In addition, we demonstrate quantum control of spins in a rotating nanodiamond. These results mark an important development in interfacing mechanical rotation with spin qubits, expanding our capacity to study quantum phenomena
The effects of Co-Ti co-doping on the magnetic, electrical, and magnetodielectric behaviors of M-type barium hexaferrites
Magnetic, electrical and magnetodielectric properties have been studied in Co-Ti co-doped M-type hexaferrite BaCoxTixFe12-2xO19 (x = 0 ∼ 4). With the incorporation of Co-Ti, both their ferromagnetic magnetization and coercivity have been greatly changed. The temperature dependent magnetization curve shows a apparent hump at around 420 K, likely in association with more complicated cycloidal spin ordering, which is closely related to ferroelectric polarization. Interestingly, a significantly enhancement in resistivity (∼3 orders in magnitude) can be obtained in co-doped samples (x > 2), which is beneficial for magnetoelectric properties. The magnetoelectric effect were examined by dielectric tunibility under external magnetic field, which shows apparent tunability up to ∼−3% for sample with x = 2 at 1T magnetic field, further supporting it is a room temperature single phase mutliferroic material