87 research outputs found
Does Synthetic Data Generation of LLMs Help Clinical Text Mining?
Recent advancements in large language models (LLMs) have led to the
development of highly potent models like OpenAI's ChatGPT. These models have
exhibited exceptional performance in a variety of tasks, such as question
answering, essay composition, and code generation. However, their effectiveness
in the healthcare sector remains uncertain. In this study, we seek to
investigate the potential of ChatGPT to aid in clinical text mining by
examining its ability to extract structured information from unstructured
healthcare texts, with a focus on biological named entity recognition and
relation extraction. However, our preliminary results indicate that employing
ChatGPT directly for these tasks resulted in poor performance and raised
privacy concerns associated with uploading patients' information to the ChatGPT
API. To overcome these limitations, we propose a new training paradigm that
involves generating a vast quantity of high-quality synthetic data with labels
utilizing ChatGPT and fine-tuning a local model for the downstream task. Our
method has resulted in significant improvements in the performance of
downstream tasks, improving the F1-score from 23.37% to 63.99% for the named
entity recognition task and from 75.86% to 83.59% for the relation extraction
task. Furthermore, generating data using ChatGPT can significantly reduce the
time and effort required for data collection and labeling, as well as mitigate
data privacy concerns. In summary, the proposed framework presents a promising
solution to enhance the applicability of LLM models to clinical text mining.Comment: 10 pages, 8 tables, 4 figure
MLPInit: Embarrassingly Simple GNN Training Acceleration with MLP Initialization
Training graph neural networks (GNNs) on large graphs is complex and
extremely time consuming. This is attributed to overheads caused by sparse
matrix multiplication, which are sidestepped when training multi-layer
perceptrons (MLPs) with only node features. MLPs, by ignoring graph context,
are simple and faster for graph data, however they usually sacrifice prediction
accuracy, limiting their applications for graph data. We observe that for most
message passing-based GNNs, we can trivially derive an analog MLP (we call this
a PeerMLP) with an equivalent weight space, by setting the trainable parameters
with the same shapes, making us curious about \textbf{\emph{how do GNNs using
weights from a fully trained PeerMLP perform?}} Surprisingly, we find that GNNs
initialized with such weights significantly outperform their PeerMLPs,
motivating us to use PeerMLP training as a precursor, initialization step to
GNN training. To this end, we propose an embarrassingly simple, yet hugely
effective initialization method for GNN training acceleration, called MLPInit.
Our extensive experiments on multiple large-scale graph datasets with diverse
GNN architectures validate that MLPInit can accelerate the training of GNNs (up
to 33X speedup on OGB-Products) and often improve prediction performance (e.g.,
up to improvement for GraphSAGE across datasets for node
classification, and up to improvement across datasets for link
prediction on metric Hits@10). The code is available at
\href{https://github.com/snap-research/MLPInit-for-GNNs}.Comment: Accepted by ICLR202
Chasing Fairness Under Distribution Shift: A Model Weight Perturbation Approach
Fairness in machine learning has attracted increasing attention in recent
years. The fairness methods improving algorithmic fairness for in-distribution
data may not perform well under distribution shifts. In this paper, we first
theoretically demonstrate the inherent connection between distribution shift,
data perturbation, and model weight perturbation. Subsequently, we analyze the
sufficient conditions to guarantee fairness (i.e., low demographic parity) for
the target dataset, including fairness for the source dataset, and low
prediction difference between the source and target datasets for each sensitive
attribute group. Motivated by these sufficient conditions, we propose robust
fairness regularization (RFR) by considering the worst case within the model
weight perturbation ball for each sensitive attribute group. We evaluate the
effectiveness of our proposed RFR algorithm on synthetic and real distribution
shifts across various datasets. Experimental results demonstrate that RFR
achieves better fairness-accuracy trade-off performance compared with several
baselines. The source code is available at
\url{https://github.com/zhimengj0326/RFR_NeurIPS23}.Comment: NeurIPS 202
Retiring DP: New Distribution-Level Metrics for Demographic Parity
Demographic parity is the most widely recognized measure of group fairness in
machine learning, which ensures equal treatment of different demographic
groups. Numerous works aim to achieve demographic parity by pursuing the
commonly used metric . Unfortunately, in this paper, we reveal that
the fairness metric can not precisely measure the violation of
demographic parity, because it inherently has the following drawbacks: i)
zero-value does not guarantee zero violation of demographic parity,
ii) values can vary with different classification thresholds. To
this end, we propose two new fairness metrics, Area Between Probability density
function Curves (ABPC) and Area Between Cumulative density function Curves
(ABCC), to precisely measure the violation of demographic parity at the
distribution level. The new fairness metrics directly measure the difference
between the distributions of the prediction probability for different
demographic groups. Thus our proposed new metrics enjoy: i) zero-value
ABCC/ABPC guarantees zero violation of demographic parity; ii) ABCC/ABPC
guarantees demographic parity while the classification thresholds are adjusted.
We further re-evaluate the existing fair models with our proposed fairness
metrics and observe different fairness behaviors of those models under the new
metrics. The code is available at
https://github.com/ahxt/new_metric_for_demographic_parityComment: Accepted by TMLR. Code available at
https://github.com/ahxt/new_metric_for_demographic_parit
Towards Assumption-free Bias Mitigation
Despite the impressive prediction ability, machine learning models show
discrimination towards certain demographics and suffer from unfair prediction
behaviors. To alleviate the discrimination, extensive studies focus on
eliminating the unequal distribution of sensitive attributes via multiple
approaches. However, due to privacy concerns, sensitive attributes are often
either unavailable or missing in real-world scenarios. Therefore, several
existing works alleviate the bias without sensitive attributes. Those studies
face challenges, either in inaccurate predictions of sensitive attributes or
the need to mitigate unequal distribution of manually defined non-sensitive
attributes related to bias. The latter requires strong assumptions about the
correlation between sensitive and non-sensitive attributes. As data
distribution and task goals vary, the strong assumption on non-sensitive
attributes may not be valid and require domain expertise. In this work, we
propose an assumption-free framework to detect the related attributes
automatically by modeling feature interaction for bias mitigation. The proposed
framework aims to mitigate the unfair impact of identified biased feature
interactions. Experimental results on four real-world datasets demonstrate that
our proposed framework can significantly alleviate unfair prediction behaviors
by considering biased feature interactions
3D carbon allotropes: Topological quantum materials with obstructed atomic insulating phases, multiple bulk-boundary correspondences, and real topology
The study of topological phases with unconventional bulk-boundary
correspondences and nontrivial real Chern number has garnered significant
attention in the topological states of matter. Using the first-principle
calculations and theoretical analysis, we perform a high-throughput material
screening of the 3D obstructed atomic insulators (OAIs) and 3D real Chern
insulators (RCIs) based on the Samara Carbon Allotrope Database (SACADA).
Results show that 422 out of 703 3D carbon allotropes are 3D OAIs with multiple
bulk-boundary correspondences, including 2D obstructed surface states (OSSs)
and 1D hinge states, which are in one dimension and two dimensions lower than
the 3D bulk, respectively. The 2D OSSs in these OAIs can be modified when
subjected to appropriate boundaries, which benefits the investigation of
surface engineering and the development of efficient topological catalysts.
These 422 OAIs, which have 2D and 1D boundary states, are excellent platforms
for multi-dimensional topological boundaries research. Remarkably, 138 of 422
OAIs are also 3D RCIs, which show a nontrivial real topology in the protection
of spacetime inversion symmetry. Our work not only provides a comprehensive
list of 3D carbon-based OAIs and RCIs, but also guides their application in
various aspects based on multiple bulk-boundary correspondences and real
topological phases
pH-Responsive Cross-Linked Low Molecular Weight Polyethylenimine as an Efficient Gene Vector for Delivery of Plasmid DNA Encoding Anti-VEGF-shRNA for Tumor Treatment
RNA interference (RNAi) is a biological process through which gene expression can be inhibited by RNA molecules with high selectivity and specificity, providing a promising tool for tumor treatment. Two types of molecules are often applied to inactivate target gene expression: synthetic double stranded small interfering RNA (siRNA) and plasmid DNA encoding short hairpin RNA (shRNA). Vectors with high transfection efficiency and low toxicity are essential for the delivery of siRNA and shRNA. In this study, TDAPEI, the synthetic derivative of low-molecular-weight polyethylenimine (PEI), was cross-linked with imine bonds by the conjugation of branched PEI (1.8 kDa) and 2,5-thiophenedicarboxaldehyde (TDA). This biodegradable cationic polymer was utilized as the vector for the delivery of plasmid DNA expressing anti-VEGF-shRNA. Compared to PEI (25 kDa), TDAPEI had a better performance since experimental results suggest its higher transfection efficiency as well as lower toxicity both in cell and animal studies. TDAPEI did not stimulate innate immune response, which is a significant factor that should be considered in vector design for gene delivery. All the results suggested that TDAPEI delivering anti-VEGF-shRNA may provide a promising method for tumor treatment
A C-X-C Chemokine Receptor Type 2–Dominated Cross-talk between Tumor Cells and Macrophages Drives Gastric Cancer Metastasis
Purpose: C-X-C chemokine receptor type 2 (CXCR2) is a key regulator that drives immune suppression and inflammation in tumor microenvironment. CXCR2-targeted therapy has shown promising results in several solid tumors. However, the underlying mechanism of CXCR2-mediated cross-talk between gastric cancer cells and macrophages still remains unclear.
Experimental Design: The expression of CXCR2 and its ligands in 155 human gastric cancer tissues was analyzed via immunohistochemistry, and the correlations with clinical characteristics were evaluated. A coculture system was established, and functional assays, including ELISA, transwell, cell viability assay, and qPCR, were performed to determine the role of the CXCR2 signaling axis in promoting gastric cancer growth and metastasis. A xenograft gastric cancer model and a lymph node metastasis model were established to study the function of CXCR2 in vivo.
Results: CXCR2 expression is associated with the prognosis of patients with gastric cancer (P = 0.002). Of all the CXCR2 ligands, CXCL1 and CXCL5 can significantly promote migration of gastric cancer cells. Macrophages are the major sources of CXCL1 and CXCL5 in the gastric cancer microenvironment, and promote migration of gastric cancer cells through activating a CXCR2/STAT3 feed-forward loop. Gastric cancer cells secrete TNF-α to induce release of CXCL1 and CXCL5 from macrophages. Inhibiting CXCR2 pathway of gastric cancer cells can suppress migration and metastasis of gastric cancer in vitro and in vivo.
Conclusions: Our study suggested a previously uncharacterized mechanism through which gastric cancer cells interact with macrophages to promote tumor growth and metastasis, suggesting that CXCR2 may serve as a promising therapeutic target to treat gastric cancer
Comprehensively Surveying Structure and Function of RING Domains from Drosophila melanogaster
Using a complete set of RING domains from Drosophila melanogaster, all the solved RING domains and cocrystal structures of RING-containing ubiquitin-ligases (RING-E3) and ubiquitin-conjugating enzyme (E2) pairs, we analyzed RING domains structures from their primary to quarternary structures. The results showed that: i) putative orthologs of RING domains between Drosophila melanogaster and the human largely occur (118/139, 84.9%); ii) of the 118 orthologous pairs from Drosophila melanogaster and the human, 117 pairs (117/118, 99.2%) were found to retain entirely uniform domain architectures, only Iap2/Diap2 experienced evolutionary expansion of domain architecture; iii) 4 evolutionary structurally conserved regions (SCRs) are responsible for homologous folding of RING domains at the superfamily level; iv) besides the conserved Cys/His chelating zinc ions, 6 equivalent residues (4 hydrophobic and 2 polar residues) in the SCRs possess good-consensus and conservation- these 4 SCRs function in the structural positioning of 6 equivalent residues as determinants for RING-E3 catalysis; v) members of these RING proteins located nucleus, multiple subcellular compartments, membrane protein and mitochondrion are respectively 42 (42/139, 30.2%), 71 (71/139, 51.1%), 22 (22/139, 15.8%) and 4 (4/139, 2.9%); vi) CG15104 (Topors) and CG1134 (Mul1) in C3HC4, and CG3929 (Deltex) in C3H2C3 seem to display broader E2s binding profiles than other RING-E3s; vii) analyzing intermolecular interfaces of E2/RING-E3 complexes indicate that residues directly interacting with E2s are all from the SCRs in RING domains. Of the 6 residues, 2 hydrophobic ones contribute to constructing the conserved hydrophobic core, while the 2 hydrophobic and 2 polar residues directly participate in E2/RING-E3 interactions. Based on sequence and structural data, SCRs, conserved equivalent residues and features of intermolecular interfaces were extracted, highlighting the presence of a nucleus for RING domain fold and formation of catalytic core in which related residues and regions exhibit preferential evolutionary conservation
HIGH-PRECISION DEM PRODUCTION FOR SPACEBORNE STEREO SAR IMAGES BASED ON SIFT MATCHING AND REGION-BASED LEAST SQUARES MATCHING
Generally, there are two ways to generate Digital Elevation Model (DEM) using synthetic aperture radar (SAR) data, which are Interferometer Synthetic Aperture Radar(InSAR) and radargrammetry. Considering the disadvantages of InSAR data, such as the limit of terrain and the influence of water content, the application field of InSAR is relatively limited, while radargrammetry is more widely applied since it does not have such limits. However, for high-precision stereo SAR imagery, since the terrain distortion caused by shooting angle cannot be eliminated and the speckle noises are obvious, the classical matching algorithms for optical stereo images do not have the same effect on SAR data.
Based on the experience of optical stereo image matching, this paper proposes a new algorithm which combines the feature of SIFT image matching, region-based least squares matching and TIN . First, SIFT matching is used as the initial matching to obtain the sparse DEM, then by using TIN the matching points are forecast, finally the region-based least squares matching is adopted to get accurate matching points. In this paper, COSMO-SkyMed and TSX stereo images of Lanzhou area are used to validate the proposed method. Experiment results show that the algorithm can be effectively used in stereo SAR matching and high-precision DEM production
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