40 research outputs found
Scribble Hides Class: Promoting Scribble-Based Weakly-Supervised Semantic Segmentation with Its Class Label
Scribble-based weakly-supervised semantic segmentation using sparse scribble
supervision is gaining traction as it reduces annotation costs when compared to
fully annotated alternatives. Existing methods primarily generate pseudo-labels
by diffusing labeled pixels to unlabeled ones with local cues for supervision.
However, this diffusion process fails to exploit global semantics and
class-specific cues, which are important for semantic segmentation. In this
study, we propose a class-driven scribble promotion network, which utilizes
both scribble annotations and pseudo-labels informed by image-level classes and
global semantics for supervision. Directly adopting pseudo-labels might
misguide the segmentation model, thus we design a localization rectification
module to correct foreground representations in the feature space. To further
combine the advantages of both supervisions, we also introduce a distance
entropy loss for uncertainty reduction, which adapts per-pixel confidence
weights according to the reliable region determined by the scribble and
pseudo-label's boundary. Experiments on the ScribbleSup dataset with different
qualities of scribble annotations outperform all the previous methods,
demonstrating the superiority and robustness of our method.The code is
available at
https://github.com/Zxl19990529/Class-driven-Scribble-Promotion-Network
Real-time counting of single electron tunneling through a T-shaped double quantum dot system
Real-time detection of single electron tunneling through a T-shaped double
quantum dot is simulated, based on a Monte Carlo scheme. The double dot is
embedded in a dissipative environment and the presence of electrons on the
double dot is detected with a nearby quantum point contact. We demonstrate
directly the bunching behavior in electron transport, which leads eventually to
a super-Poissonian noise. Particularly, in the context of full counting
statistics, we investigate the essential difference between the dephasing
mechanisms induced by the quantum point contact detection and the coupling to
the external phonon bath. A number of intriguing noise features associated with
various transport mechanisms are revealed.Comment: 8 pages, 5 figure
Overview of the MOSAiC expedition: Physical oceanography
Arctic Ocean properties and processes are highly relevant to the regional and global coupled climate system,
yet still scarcely observed, especially in winter. Team OCEAN conducted a full year of physical oceanography
observations as part of the Multidisciplinary drifting Observatory for the Study of the Arctic Climate
(MOSAiC), a drift with the Arctic sea ice from October 2019 to September 2020. An international team
designed and implemented the program to characterize the Arctic Ocean system in unprecedented detail, from
the seafloor to the air-sea ice-ocean interface, from sub-mesoscales to pan-Arctic. The oceanographic
measurements were coordinated with the other teams to explore the ocean physics and linkages to the
climate and ecosystem. This paper introduces the major components of the physical oceanography program
and complements the other team overviews of the MOSAiC observational program. Team OCEAN’s sampling
strategy was designed around hydrographic ship-, ice- and autonomous platform-based measurements to
improve the understanding of regional circulation and mixing processes. Measurements were carried out
both routinely, with a regular schedule, and in response to storms or opening leads. Here we present alongdrift time series of hydrographic properties, allowing insights into the seasonal and regional evolution of the
water column from winter in the Laptev Sea to early summer in Fram Strait: freshening of the surface,
deepening of the mixed layer, increase in temperature and salinity of the Atlantic Water. We also highlight
the presence of Canada Basin deep water intrusions and a surface meltwater layer in leads. MOSAiC most
likely was the most comprehensive program ever conducted over the ice-covered Arctic Ocean. While data
analysis and interpretation are ongoing, the acquired datasets will support a wide range of physical
oceanography and multi-disciplinary research. They will provide a significant foundation for assessing and
advancing modeling capabilities in the Arctic Ocean
LEFT-LATERALIZED N170 RESPONSE TO UNPRONOUNCEABLE PSEUDO BUT NOT FALSE CHINESE CHARACTERS-THE KEY ROLE OF ORTHOGRAPHY
A negative event-related potential (ERP) component, known as N170, can be readily recorded over the posterior left brain region when skilled readers are presented with visual words. This left-lateralized word-related N170 has been attributed either to linguistic processes, particularly phonological processing, or to the role of orthographic regularity, emphasizing a perceptual origin. This debate, however, is difficult to resolve in the context of alphabetic scripts because of the tight relations between orthography and phonology. In contrast, Chinese characters have arbitrary mappings between orthographic and sound forms, making it possible to tease apart these two properties of visual words. We therefore addressed this issue by examining ERP responses to Chinese characters and three types of structurally matched but unpronounceable stimuli: pseudo-characters, false-characters, and stroke combinations. A content-irrelevant color matching task was adopted to minimize potentially different top-down modulations across stimulus types. Results show that, relative to false-characters and stroke combinations, real- and pseudo-characters evoked greater N170 in the left posterior brain region. Critically, despite being unpronounceable, pseudo-characters produced the same amplitude and left-lateralized N170, just as real-characters. These results provide strong evidence that orthography rather than phonology serves as the main driver for the enhanced and left-lateralized N170 to visual words. (C) 2011 IBRO. Published by Elsevier Ltd. All rights reserved
Functional brain hubs and their test-retest reliability: A multiband resting-state functional MRI study
Resting-state functional MRI (R-fMRI) has emerged as a promising neuroimaging technique used to identify global hubs of the human brain functional connectome. However, most R-fMRI studies on functional hubs mainly utilize traditional R-fMRI data with relatively low sampling rates (e.g., repetition time [TR] = 2 s). R-fMRI data scanned with higher sampling rates are important for the characterization of reliable functional connectomes because they can provide temporally complementary information about functional integration among brain regions and simultaneously reduce the effects of high frequency physiological noise. Here, we employed a publicly available multiband R-fMRI dataset with a sub-second sampling rate (TR = 645 ms) to identify global hubs in the human voxel-wise functional networks, and further examined their test-retest (TRT) reliability over scanning time. We showed that the functional hubs of human brain networks were mainly located at the default-mode regions (e.g., medial prefrontal and parietal cortex as well as the lateral parietal and temporal cortex) and the sensorimotor and visual cortex. These hub regions were highly anatomically distance-dependent, where short-range and long-range hubs were primarily located at the primary cortex and the multimodal association cortex, respectively. We found that most functional hubs exhibited fair to good TRT reliability using intraclass correlation coefficients. Interestingly, our analysis suggested that a 6-minute scan duration was able to reliably detect these functional hubs. Further comparison analysis revealed that these results were approximately consistent with those obtained using traditional R-fMRI scans of the same subjects with TR = 2500 ms, but several regions (e.g., lateral frontal cortex, paracentral lobule and anterior temporal lobe) exhibited different TRT reliability. Finally, we showed that several regions (including the medial/lateral prefrontal cortex and lateral temporal cortex) were identified as brain hubs in a high frequency band (02-03 Hz), which is beyond the frequency scope of traditional R-fMRI scans. Our results demonstrated the validity of multiband R4MRI data to reliably detect functional hubs in the voxel-wise whole-brain networks, which motivated the acquisition of high temporal resolution R-fMRI data for the studies of human brain functional connectomes in healthy and diseased conditions. (C) 2013 Elsevier Inc. All rights reserved.</p
Structural and photoluminescent properties of ternary Zn1-xCdxO crystal films grown on Si(111) substrates
The ternary Zn1-xCdxO (0less than or equal toxless than or equal to0.6) alloying films with highly c-axis orientation have been deposited on Si(111) substrates by direct current reactive magnetron sputtering method. X-ray diffraction measurement indicates that the wurtzite-type structure of ZnO can be stabilized up to nominal Cd content x similar to 0.6 without cubic CdO phase separation. The lattice parameter c of Zn1-xCdxO increases almost linearly from 5.229 Angstrom (x = 0) to 5.247 Angstrom (x = 0.6), indicating that Cd substitution takes place on the Zn lattice sites. The photoluminescence spectra of the Zn1-xCdxO thin films measured at 12 K display a substantial red shift (similar to0.3 eV) in the near-band-edges (NBEs) emission of ZnO: from 3.39 eV of ZnO to 3.00 eV of Zn0.4Cd0.6O. The direct modulation of band gap caused by Zn/Cd substitution is responsible for the red shift effect in NBE emission of ZnO. (C) 2003 Elsevier Science B.V. All rights reserved
Assessing adsorption of polycyclic aromatic hydrocarbons on Rhizopus oryzae cell wall components with water-methanol cosolvent model
The contribution of different fungal cell wall components in adsorption of polycyclic aromatic hydrocarbons (PAHs) is still unclear. We isolated Rhizopus oryzae cell walls components with sequential extraction, characterized functional groups with NEXAFS spectra, and determined partition coefficients of PAHs on cell walls and cell wall components with cosolvent model. Spectra of NEXAFS indicated that isolated cell walls components were featured with peaks at similar to 532.7 and similar to 534.5 eV energy. The lipid cosolvent partition coefficients were approximately one order of magnitude higher than the corresponding carbohydrate cosolvent partition coefficients. The partition coefficients for four tested carbohydrates varied at approximate 0.5 logarithmic units. Partition coefficients between biosorbents and water calculated based cosolvent models ranged from 0.8 to 4.2. The present study proved the importance of fungal cell wall components in adsorption of PAHs, and consequently the role of fungi in PAHs bioremediation. (C) 2015 Elsevier Inc. All rights reserved