2,219 research outputs found
Contrastive Brain Network Learning via Hierarchical Signed Graph Pooling Model
Recently brain networks have been widely adopted to study brain dynamics,
brain development and brain diseases. Graph representation learning techniques
on brain functional networks can facilitate the discovery of novel biomarkers
for clinical phenotypes and neurodegenerative diseases. However, current graph
learning techniques have several issues on brain network mining. Firstly, most
current graph learning models are designed for unsigned graph, which hinders
the analysis of many signed network data (e.g., brain functional networks).
Meanwhile, the insufficiency of brain network data limits the model performance
on clinical phenotypes predictions. Moreover, few of current graph learning
model is interpretable, which may not be capable to provide biological insights
for model outcomes. Here, we propose an interpretable hierarchical signed graph
representation learning model to extract graph-level representations from brain
functional networks, which can be used for different prediction tasks. In order
to further improve the model performance, we also propose a new strategy to
augment functional brain network data for contrastive learning. We evaluate
this framework on different classification and regression tasks using the data
from HCP and OASIS. Our results from extensive experiments demonstrate the
superiority of the proposed model compared to several state-of-the-art
techniques. Additionally, we use graph saliency maps, derived from these
prediction tasks, to demonstrate detection and interpretation of phenotypic
biomarkers
New Supernova Candidates from SDSS-DR7 of Spectral Survey
The letter presents 25 discovered supernova candidates from SDSS-DR7 with our
dedicated method, called Sample Decrease, and 10 of them were confirmed by
other research groups, and listed in this letter. Another 15 are first
discovered including 14 type Ia and one type II based on Supernova
Identification (SNID) analysis. The results proved that our method is reliable,
and the description of the method and some detailed spectra analysis procedures
were also presented in this letter.Comment: 6 pages, 3 figure
3D bi-directional transformer U-Net for medical image segmentation
As one of the popular deep learning methods, deep convolutional neural networks (DCNNs) have been widely adopted in segmentation tasks and have received positive feedback. However, in segmentation tasks, DCNN-based frameworks are known for their incompetence in dealing with global relations within imaging features. Although several techniques have been proposed to enhance the global reasoning of DCNN, these models are either not able to gain satisfying performances compared with traditional fully-convolutional structures or not capable of utilizing the basic advantages of CNN-based networks (namely the ability of local reasoning). In this study, compared with current attempts to combine FCNs and global reasoning methods, we fully extracted the ability of self-attention by designing a novel attention mechanism for 3D computation and proposed a new segmentation framework (named 3DTU) for three-dimensional medical image segmentation tasks. This new framework processes images in an end-to-end manner and executes 3D computation on both the encoder side (which contains a 3D transformer) and the decoder side (which is based on a 3D DCNN). We tested our framework on two independent datasets that consist of 3D MRI and CT images. Experimental results clearly demonstrate that our method outperforms several state-of-the-art segmentation methods in various metrics
Bioactive compounds from Rumex plants
Two new naphthalene acylglucosides, rumexneposides A (1) and B (2), together with 12 known
compounds (3-14), were isolated from the roots of Rumex nepalensis. Their structures were established
by chemical and spectroscopic methods. The biological activities of compounds 1-14 as well as an
additional 11 compounds previously isolated from R. nepalensis and Rumex hastatus (15–25) were
evaluated against Mycobacterium tuberculosis, para-aminobenzoic acid (pAba) pathway, and a panel of
human cancer cell lines. The results showed that compound 15 was the most active against M.
tuberculosis with an MIC value of 2.85 mM similar to that of isoniazid. Compound 5 could inhibit pAba
synthetic pathway with an MIC value of 12.6 mM, comparable to that of positive control abyssomicin C,
representing a new example of the rare pAba pathway inhibitors
WISDOM Project -- XV. Giant Molecular Clouds in the Central Region of the Barred Spiral Galaxy NGC 5806
We present high spatial resolution ( pc) Atacama Large
Millimeter/sub-millimeter Array CO(2-1) observations of the central
region of the nearby barred spiral galaxy NGC 5806. NGC 5806 has a highly
structured molecular gas distribution with a clear nucleus, a nuclear ring and
offset dust lanes. We identify spatially- and spectrally-resolved giant
molecular clouds (GMCs). These clouds have comparable sizes ()
and larger gas masses, observed linewidths () and
gas mass surface densities than those of clouds in the Milky Way disc. The size
-- linewidth relation of the clouds is one of the steepest reported so far
(), the clouds are on
average only marginally bound (with a mean virial parameter
), and high velocity dispersions
are observed in the nuclear ring. These behaviours are likely due to bar-driven
gas shocks and inflows along the offset dust lanes, and we infer an inflow
velocity of kms and a total molecular gas mass inflow rate
of M yr into the nuclear ring. The observed internal
velocity gradients of the clouds are consistent with internal turbulence. The
number of clouds in the nuclear ring decreases with azimuthal angle downstream
from the dust lanes without clear variation of cloud properties. This is likely
due to the estimated short lifetime of the clouds ( Myr), which
appears to be mainly regulated by cloud-cloud collision and/or shear processes.
Overall, it thus seems that the presence of the large-scale bar and gas inflows
to the centre of NGC 5806 affect cloud properties.Comment: Accepted for publication in MNRAS, 20 pages, 16 figure
Estimating dust attenuation from galactic spectra : II. stellar and gas attenuation in star-forming and diffuse ionized gas regions in MaNGA
We investigate the dust attenuation in both stellar populations and ionized gas in kiloparsec-scale regions in nearby galaxies using integral field spectroscopy data from MaNGA MPL-9. We identify star-forming (H II) and diffuse ionized gas (DIG) regions from MaNGA data cubes. From the stacked spectrum of each region, we measure the stellar attenuation, E( ) B V - star, using the technique developed by Li et al., as well as the gas attenuation, E( ) B V - gas, from the Balmer decrement. We then examine the correlation of E( ) B V - star, E( ) B V - gas, E() () B V EB V - -- gas star, and E( )( ) B V EB V - - star gas with 16 regional/global properties, and for regions with different Hα surface brightnesses (ΣHα). We find a stronger correlation between E( ) B V - star and E( ) B V - gas in regions of higher ΣHα. The luminosity-weighted age (tL) is found to be the property that is the most strongly correlated with E( ) B V - star, and consequently, with E() () B V EB V - -- gas star and E( )( ) B V EB V - - star gas. At fixed ΣHα, log10tL is linearly and negatively correlated with E( ) B V - star E( ) B V - gas at all ages. Gas-phase metallicity and ionization level are important for the attenuation in the gas. Our results indicate that the ionizing source for DIG regions is likely distributed in the outskirts of galaxies, while for H II regions, our results can be well explained by the two-component dust model of Charlot & Fall
Lasting DNA Damage and Aberrant DNA Repair Gene Expression Profile Are Associated with Post-Chronic Cadmium Exposure in Human Bronchial Epithelial Cells
Cadmium (Cd) is a widespread environmental pollutant and carcinogen. Although the exact mechanisms of Cd-induced carcinogenesis remain unclear, previous acute/chronic Cd exposure studies have shown that Cd exerts its cytotoxic and carcinogenic effects through multiple mechanisms, including interference with the DNA repair system. However, the effects of post-chronic Cd exposure remain unknown. Here, we establish a unique post-chronic Cd-exposed human lung cell model (the CR0 cells) and investigate the effects of post-chronic Cd exposure on the DNA repair system. We found that the CR0 cells retained Cd-resistant property even though it was grown in Cd-free culture medium for over a year. The CR0 cells had lasting DNA damage due to reduced DNA repair capacity and an aberrant DNA repair gene expression profile. A total of 12 DNA repair genes associated with post-chronic Cd exposure were identified, and they could be potential biomarkers for identifying post-chronic Cd exposure. Clinical database analysis suggests that some of the DNA repair genes play a role in lung cancer patients with different smoking histories. Generally, CR0 cells were more sensitive to chemotherapeutic (cisplatin, gemcitabine, and vinorelbine tartrate) and DNA damaging (H2O2) agents, which may represent a double-edged sword for cancer prevention and treatment. Overall, we demonstrated for the first time that the effects of post-chronic Cd exposure on human lung cells are long-lasting and different from that of acute and chronic exposures. Findings from our study unveiled a new perspective on Cd-induced carcinogenesis-the post-chronic exposure of Cd. This study encourages the field of post-exposure research which is crucial but has long been ignored
- …