29 research outputs found
Evaluating Feature Attribution Methods for Electrocardiogram
The performance of cardiac arrhythmia detection with electrocardiograms(ECGs)
has been considerably improved since the introduction of deep learning models.
In practice, the high performance alone is not sufficient and a proper
explanation is also required. Recently, researchers have started adopting
feature attribution methods to address this requirement, but it has been
unclear which of the methods are appropriate for ECG. In this work, we identify
and customize three evaluation metrics for feature attribution methods based on
the characteristics of ECG: localization score, pointing game, and degradation
score. Using the three evaluation metrics, we evaluate and analyze eleven
widely-used feature attribution methods. We find that some of the feature
attribution methods are much more adequate for explaining ECG, where Grad-CAM
outperforms the second-best method by a large margin.Comment: 5 pages, 3 figures. Code is available at
https://github.com/SNU-DRL/Attribution-EC
Isotropic Representation Can Improve Dense Retrieval
The recent advancement in language representation modeling has broadly
affected the design of dense retrieval models. In particular, many of the
high-performing dense retrieval models evaluate representations of query and
document using BERT, and subsequently apply a cosine-similarity based scoring
to determine the relevance. BERT representations, however, are known to follow
an anisotropic distribution of a narrow cone shape and such an anisotropic
distribution can be undesirable for the cosine-similarity based scoring. In
this work, we first show that BERT-based DR also follows an anisotropic
distribution. To cope with the problem, we introduce unsupervised
post-processing methods of Normalizing Flow and whitening, and develop
token-wise method in addition to the sequence-wise method for applying the
post-processing methods to the representations of dense retrieval models. We
show that the proposed methods can effectively enhance the representations to
be isotropic, then we perform experiments with ColBERT and RepBERT to show that
the performance (NDCG at 10) of document re-ranking can be improved by
5.17\%8.09\% for ColBERT and 6.88\%22.81\% for RepBERT. To examine
the potential of isotropic representation for improving the robustness of DR
models, we investigate out-of-distribution tasks where the test dataset differs
from the training dataset. The results show that isotropic representation can
achieve a generally improved performance. For instance, when training dataset
is MS-MARCO and test dataset is Robust04, isotropy post-processing can improve
the baseline performance by up to 24.98\%. Furthermore, we show that an
isotropic model trained with an out-of-distribution dataset can even outperform
a baseline model trained with the in-distribution dataset.Comment: 9 pages, 4 figure
In vivo and in vitro safety evaluation of fermented Citrus sunki peel extract: acute and 90-day repeated oral toxicity studies with genotoxicity assessment
Abstract
Background
Citrus sunki Hort. ex Tanaka peel has been traditionally used as an ingredient in folk medicine due to its therapeutic effects on promotion of splenic health and diuresis as well as relief of gastrointestinal symptoms. Although a growing interest in health-promoting natural products and the development of highly concentrated products have facilitated consumption of C. sunki peel, its safety assessment has not been explored, posing a potential health risk. In this study, we carried out a series of systemic and genetic toxicity tests on fermented C. sunki peel extract (FCPE) to provide the essential information required for safe use in human.
Methods
We conducted acute and 90-day repeated oral toxicity studies in Sprague-Dawley rats to evaluate systemic toxicity, and three genotoxicity assays to measure bacterial mutation reversion, cellular chromosome aberration and in vivo micronucleus formation.
Results
Single oral administration of FCPE did not cause any clinical signs and lethality in all animals, establishing LD50 to be over 2000 mg/kg BW. Repeated administration of up to 2000 mg/kg BW FCPE for 90 days revealed no test substance-related toxicity as demonstrated in analysis of body weight gain, food/water intake, blood, serum biochemistry, organweight and histopathology, collectively determining that the no-observable-adverse-effect-level of FCPE is over 2000 mg/kg BW. In addition, we detected no mutagenicity and clastogenicity in FCPE at 5000 μg/plate for the in vitro assays and 2000 mg/kg BW for the in vivo micronucleus test.
Conclusion
FCPE did not cause systemic and genetic toxicity in our model systems at the tested dose levels. These results suggest a guideline for safe consumption of C. sunki peel in human