4,848 research outputs found
Dynamical mean-field theory of Hubbard-Holstein model at half-filling: Zero temperature metal-insulator and insulator-insulator transitions
We study the Hubbard-Holstein model, which includes both the
electron-electron and electron-phonon interactions characterized by and
, respectively, employing the dynamical mean-field theory combined with
Wilson's numerical renormalization group technique. A zero temperature phase
diagram of metal-insulator and insulator-insulator transitions at half-filling
is mapped out which exhibits the interplay between and . As () is
increased, a metal to Mott-Hubbard insulator (bipolaron insulator) transition
occurs, and the two insulating states are distinct and can not be adiabatically
connected. The nature of and transitions between the three states are
discussed.Comment: 5 pages, 4 figures. Submitted to Physical Review Letter
Influences of small-scale oscillations on growth inhibition and ultrastructural changes of Microcystis cells
We investigated the effects of small-scale oscillation (SSO) on toxic Microcystis cells. The oscillating device was made of silicon with two axes that had a diameter of similar to 40 mm, and a frequency of 2.5 Hz was observed at 150 rpm. The SSO was effective in inhibiting Microcystis growth. Microcystin release was not observed, whereas cell density barely increased in the oscillating group. Cell size and morphology of the oscillating group were no different from the control group. However, cell quotas of chl.a and microcystin in the oscillating group were half the level of the control group. Crucially, a number of large-sized holes were observed and layered long linear thylakoids were rarely observed in the oscillating group. Therefore, SSO was found to be very effective in Microcystis growth inhibition, and it caused ultrastructural changes without damage to the cell membrane and subsequent microcystin release.ArticleJournal of Environmental Science and Health, Part A.53(13):1161-1166(2018)journal articl
Theory of magnetic field-induced metaelectric critical end point in BiMnO
A recent experiment on the multiferroic BiMnO compound under a strong
applied magnetic field revealed a rich phase diagram driven by the coupling of
magnetic and charge (dipolar) degrees of freedom. Based on the
exchange-striction mechanism, we propose here a theoretical model with the
intent to capture the interplay of the spin and dipolar moments in the presence
of a magnetic field in BiMnO. Experimentally observed behavior of the
dielectric constants, magnetic susceptibility, and the polarization is, for the
most part, reproduced by our model. The critical behavior observed near the
polarization reversal point in the phase diagram is interpreted as
arising from the proximity to the critical end point.Comment: Theory; relevant experiment uploaded as arXiv:0810.190
High-fidelity 3D Human Digitization from Single 2K Resolution Images
High-quality 3D human body reconstruction requires high-fidelity and
large-scale training data and appropriate network design that effectively
exploits the high-resolution input images. To tackle these problems, we propose
a simple yet effective 3D human digitization method called 2K2K, which
constructs a large-scale 2K human dataset and infers 3D human models from 2K
resolution images. The proposed method separately recovers the global shape of
a human and its details. The low-resolution depth network predicts the global
structure from a low-resolution image, and the part-wise image-to-normal
network predicts the details of the 3D human body structure. The
high-resolution depth network merges the global 3D shape and the detailed
structures to infer the high-resolution front and back side depth maps.
Finally, an off-the-shelf mesh generator reconstructs the full 3D human model,
which are available at https://github.com/SangHunHan92/2K2K. In addition, we
also provide 2,050 3D human models, including texture maps, 3D joints, and SMPL
parameters for research purposes. In experiments, we demonstrate competitive
performance over the recent works on various datasets.Comment: code page : https://github.com/SangHunHan92/2K2K, Accepted to CVPR
2023 (Highlight
KHAN: Knowledge-Aware Hierarchical Attention Networks for Accurate Political Stance Prediction
The political stance prediction for news articles has been widely studied to
mitigate the echo chamber effect -- people fall into their thoughts and
reinforce their pre-existing beliefs. The previous works for the political
stance problem focus on (1) identifying political factors that could reflect
the political stance of a news article and (2) capturing those factors
effectively. Despite their empirical successes, they are not sufficiently
justified in terms of how effective their identified factors are in the
political stance prediction. Motivated by this, in this work, we conduct a user
study to investigate important factors in political stance prediction, and
observe that the context and tone of a news article (implicit) and external
knowledge for real-world entities appearing in the article (explicit) are
important in determining its political stance. Based on this observation, we
propose a novel knowledge-aware approach to political stance prediction (KHAN),
employing (1) hierarchical attention networks (HAN) to learn the relationships
among words and sentences in three different levels and (2) knowledge encoding
(KE) to incorporate external knowledge for real-world entities into the process
of political stance prediction. Also, to take into account the subtle and
important difference between opposite political stances, we build two
independent political knowledge graphs (KG) (i.e., KG-lib and KG-con) by
ourselves and learn to fuse the different political knowledge. Through
extensive evaluations on three real-world datasets, we demonstrate the
superiority of DASH in terms of (1) accuracy, (2) efficiency, and (3)
effectiveness.Comment: 12 pages, 5 figures, 10 tables, the Web Conference 2023 (WWW
Genotypic Characterization of Vibrio vulnificus Clinical Isolates in Korea
AbstractObjectivesVibrio vunificus is known to cause septicemia and severe wound infections in patients with chronic liver diseases or an immuno-compromised condition. We carried out the molecular characterization of V. vulnificus isolates from human Vibrio septicemia cases based on pulsed-field gel electrophoresis (PFGE) using NotI and SfiI.Methods and ResultsPFGE was used to characterize a total of 78 strains from clinical cases after NotI or SfiI digestion. The geographical distribution of PFGE patterns for the strains from the southern part of Korea, a high-risk region for Vibrio septicemia, indicated that the isolates from southeastern Korea showed a comparatively higher degree of homology than those from southwestern Korea.ConclusionsWe report the genetic distribution of V. vulnficus isolated from Vibrio septicemia cases during 2000–2004 in Korea. This method has potential use as a subspecies-typing tool for V. vulnificus strains isolated from distant geographic regions
Elimination of Chrysanthemum stunt viroid (CSVd) from Meristem Tip Culture Combined with Prolonged Cold Treatment
Chrysanthemum production in Korea has recently been greatly affected by the spread of Chrysanthemum stunt viroid (CSVd) infection, necessitating the use of CSVd-free stocks to ensure successful chrysanthemum cultivation. We investigated the effects of low temperature (4°C), antiviral chemicals (ribavirin and amantadine) and a combination of these treatments on CSVd elimination by meristem tip cultures using plantlets that originated from CSVd-infected chrysanthemum ‘Ency’. Neither antiviral agents led to CSVd elimination, despite the suppression of meristem tip growth in a concentration dependent manner. However, the CSVd elimination rate increased up to 42.8% when meristem tips were excised after storage at 4°C for two months. The most effective results were obtained from a combination of low temperature for three months at 4°C followed by meristem tip culture on media containing 50 and 100 mgL-1 ribavirin. These results suggest that antiviral agents can also be useful for CSVd elimination if their treatment is combined with prolonged periods of low temperature. This is the first report of eradication of viroids from spray type chrysanthemum bred in Korea
Image-to-Image Retrieval by Learning Similarity between Scene Graphs
As a scene graph compactly summarizes the high-level content of an image in a
structured and symbolic manner, the similarity between scene graphs of two
images reflects the relevance of their contents. Based on this idea, we propose
a novel approach for image-to-image retrieval using scene graph similarity
measured by graph neural networks. In our approach, graph neural networks are
trained to predict the proxy image relevance measure, computed from
human-annotated captions using a pre-trained sentence similarity model. We
collect and publish the dataset for image relevance measured by human
annotators to evaluate retrieval algorithms. The collected dataset shows that
our method agrees well with the human perception of image similarity than other
competitive baselines.Comment: Accepted to AAAI 202
Rapid Dye Regeneration Mechanism of Dye-Sensitized Solar Cells
During the light-harvesting process of dye-sensitized solar cells (DSSCs), the hole localized on the dye after the charge separation yields an oxidized dye, D^+. The fast regeneration of D^+ using the redox pair (typically the I^–/I_(3)^– couple) is critical for the efficient DSSCs. However, the kinetic processes of dye regeneration remain uncertain, still promoting vigorous debates. Here, we use molecular dynamics simulations to determine that the inner-sphere electron-transfer pathway provides a rapid dye regeneration route of ∼4 ps, where penetration of I^− next to D^+ enables an immediate electron transfer, forming a kinetic barrier. This explains the recently reported ultrafast dye regeneration rate of a few picoseconds determined experimentally. We expect that our MD based comprehensive understanding of the dye regeneration mechanism will provide a helpful guideline in designing TiO_2−dye−electrolyte interfacial systems for better performing DSSCs
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