72 research outputs found
Deep Learning for Person Reidentification Using Support Vector Machines
© 2017 Mengyu Xu et al. Due to the variations of viewpoint, pose, and illumination, a given individual may appear considerably different across different camera views. Tracking individuals across camera networks with no overlapping fields is still a challenging problem. Previous works mainly focus on feature representation and metric learning individually which tend to have a suboptimal solution. To address this issue, in this work, we propose a novel framework to do the feature representation learning and metric learning jointly. Different from previous works, we represent the pairs of pedestrian images as new resized input and use linear Support Vector Machine to replace softmax activation function for similarity learning. Particularly, dropout and data augmentation techniques are also employed in this model to prevent the network from overfitting. Extensive experiments on two publically available datasets VIPeR and CUHK01 demonstrate the effectiveness of our proposed approach
SegRefiner: Towards Model-Agnostic Segmentation Refinement with Discrete Diffusion Process
In this paper, we explore a principal way to enhance the quality of object
masks produced by different segmentation models. We propose a model-agnostic
solution called SegRefiner, which offers a novel perspective on this problem by
interpreting segmentation refinement as a data generation process. As a result,
the refinement process can be smoothly implemented through a series of
denoising diffusion steps. Specifically, SegRefiner takes coarse masks as
inputs and refines them using a discrete diffusion process. By predicting the
label and corresponding states-transition probabilities for each pixel,
SegRefiner progressively refines the noisy masks in a conditional denoising
manner. To assess the effectiveness of SegRefiner, we conduct comprehensive
experiments on various segmentation tasks, including semantic segmentation,
instance segmentation, and dichotomous image segmentation. The results
demonstrate the superiority of our SegRefiner from multiple aspects. Firstly,
it consistently improves both the segmentation metrics and boundary metrics
across different types of coarse masks. Secondly, it outperforms previous
model-agnostic refinement methods by a significant margin. Lastly, it exhibits
a strong capability to capture extremely fine details when refining
high-resolution images. The source code and trained models are available at
https://github.com/MengyuWang826/SegRefiner.Comment: NeurIPS 2023, Code: https://github.com/MengyuWang826/SegRefine
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Viruses mobilize plant immunity to deter nonvector insect herbivores.
A parasite-infected host may promote performance of associated insect vectors; but possible parasite effects on nonvector insects have been largely unexplored. Here, we show that Begomovirus, the largest genus of plant viruses and transmitted exclusively by whitefly, reprogram plant immunity to promote the fitness of the vector and suppress performance of nonvector insects (i.e., cotton bollworm and aphid). Infected plants accumulated begomoviral βC1 proteins in the phloem where they were bound to the plant transcription factor WRKY20. This viral hijacking of WRKY20 spatiotemporally redeployed plant chemical immunity within the leaf and had the asymmetrical benefiting effects on the begomoviruses and its whitefly vectors while negatively affecting two nonvector competitors. This type of interaction between a parasite and two types of herbivores, i.e., vectors and nonvectors, occurs widely in various natural and agricultural ecosystems; thus, our results have broad implications for the ecological significance of parasite-vector-host tripartite interactions
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Mg3(Bi,Sb)2 single crystals towards high thermoelectric performance
The rapid growth of the thermoelectric cooler market makes the development of novel room temperature thermoelectric materials of great importance. Ternary n-type Mg3(Bi,Sb)2 alloys are promising alternatives to the state-of-the-art Bi2(Te,Se)3 alloys but grain boundary resistance is the most important limitation. n-type Mg3(Bi,Sb)2 single crystals with negligible grain boundaries are expected to have particularly high zT but have rarely been realized due to the demanding Mg-rich growth conditions required. Here, we report, for the first time, the thermoelectric properties of n-type Mg3(Bi,Sb)2 alloyed single crystals grown by a one-step Mg-flux method using sealed tantalum tubes. High weighted mobility ∼140 cm2 V−1 s−1 and a high zT of 0.82 at 315 K are achieved in Y-doped Mg3Bi1.25Sb0.75 single crystals. Through both experimental angle-resolved photoemission spectroscopy and theoretical calculations, we denote the origin of the high thermoelectric performance from a point of view of band widening effect and electronegativity, as well as the necessity to form high Bi/Sb ratio ternary Mg3(Bi,Sb)2 alloys. The present work paves the way for further development of Mg3(Bi,Sb)2 for near room temperature thermoelectric applications
Consecutive Slides on Axial View Is More Effective Than Transversal Diameter to Differentiate Mechanisms of Single Subcortical Infarctions in the Lenticulostriate Artery Territory
Objective: Lipohyalinosis or atherosclerosis might be responsible for single subcortical infarctions (SSIs); however, ways of differentiating between the two clinically remain uncertain. We aimed to investigate whether consecutive slides on axial view or transversal diameter is more effective to differentiate mechanisms by comparing their relationships with white matter hyperintensities (WMHs).Methods: All the participants from the Standard Medical Management in Secondary Prevention of Ischemic stroke in China (SMART) cohort who had SSIs in the lenticulostriate artery territory were included and categorized according to consecutive slides on axial view (≥4 consecutive slices or not) and transversal diameter (≥15 mm or not). The associations between the severity of WMHs and the different categories were analyzed.Results: Among the 3,821 patients of the SMART study, 281 had diffusion-weighted image-proven SSIs in the lenticulostriate artery territory. When classified by consecutive slides on axial view, SSIs on ≥4 slices were significantly associated with the severity of the WMHs, both in deep WMH (DWMH) (odds ratio [OR], 0.32; 95% confidence interval [CI], 0.11–0.97; p = 0.04) and periventricular hyperintensity (PVH) (OR, 0.37; 95% CI, 0.17–0.78; p = 0.01). No such association was found on the basis of the transversal diameter (p > 0.1).Conclusion: Consecutive slides on axial view (≥4 consecutive slices) might be more effective than transversal diameter to identify the atherosclerotic mechanisms of SSIs in the lenticulostriate artery territory.Clinical Trial Registration:http://www.clinicaltrials.gov. Unique identifier: NCT0066484
Anomalous quasiparticles in the zone center electron pocket of the kagom\'e ferromagnet Fe3Sn2
One material containing kagome bilayers and featuring both exceptional
magnetism and electron transport is the ferromagnetic metal Fe3Sn2.
Notwithstanding the widespread interest in Fe3Sn2, crystal twinning,
difficulties in distinguishing surface from bulk states, and a large unit cell
have until now prevented the synchrotron-based spectroscopic observation of
sharply resolved quasiparticles near the Fermi surface which could be
responsible for the anomalous properties appearing at low temperatures for the
material. Here we report microfocused laser-based angle-resolved photoemission
spectroscopy (micro-ARPES), which offers the first look at such quasiparticles.
The high spatial resolution allows individual crystal twin domains to be
examined in isolation, resulting in the discovery of three-fold symmetric
electron pockets at the Brillouin zone (BZ) center, not predicted by early
tight-binding descriptions but in agreement with density functional theory
(DFT) calculations, which also feature Weyl nodes. The quasiparticles in these
pockets have remarkably long mean free paths, and their Fermi surface area is
consistent with reported quantum oscillations. At the same time, though, the
best-defined Fermi surface is reduced at low temperature, and the
quasiparticles generally are marginal in the sense that their wavelength
uncertainty is of order the deviation of the quasiparticle wavelength from the
Fermi vector. We attribute these manifestations of strong electron-electron
interactions to a flat band predicted by our DFT to lie just above the
dispersive bands seen in this experiment. Thus, beyond demonstrating the impact
of twin averaging for ARPES measurements of band structures, our experiments
reveal many-body physics unaccounted for by current theories of metallic kagome
ferromagnets
Three-dimensional quasi-quantized Hall insulator phase in SrSi2
In insulators, the longitudinal resistivity becomes infinitely large at zero
temperature. For classic insulators, the Hall conductivity becomes zero at the
same time. However, there are special systems, such as two-dimensional quantum
Hall isolators, in which a more complex scenario is observed at high magnetic
fields. Here, we report experimental evidence for a quasi-quantized Hall
insulator in the quantum limit of the three-dimensional semimetal SrSi2. Our
measurements reveal a magnetic field-range, in which the longitudinal
resistivity diverges with decreasing temperature, while the Hall conductivity
approaches a quasi-quantized value that is given only by the conductance
quantum and the Fermi wave vector in the field-direction. The quasi-quantized
Hall insulator appears in a magnetic-field induced insulating ground state of
three-dimensional materials and is deeply rooted in quantum Hall physics.Comment: 29 pages including SI, 3 main figures and 6 SI figure
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