357 research outputs found
Diffusion Model as Representation Learner
Diffusion Probabilistic Models (DPMs) have recently demonstrated impressive
results on various generative tasks.Despite its promises, the learned
representations of pre-trained DPMs, however, have not been fully understood.
In this paper, we conduct an in-depth investigation of the representation power
of DPMs, and propose a novel knowledge transfer method that leverages the
knowledge acquired by generative DPMs for recognition tasks. Our study begins
by examining the feature space of DPMs, revealing that DPMs are inherently
denoising autoencoders that balance the representation learning with
regularizing model capacity. To this end, we introduce a novel knowledge
transfer paradigm named RepFusion. Our paradigm extracts representations at
different time steps from off-the-shelf DPMs and dynamically employs them as
supervision for student networks, in which the optimal time is determined
through reinforcement learning. We evaluate our approach on several image
classification, semantic segmentation, and landmark detection benchmarks, and
demonstrate that it outperforms state-of-the-art methods. Our results uncover
the potential of DPMs as a powerful tool for representation learning and
provide insights into the usefulness of generative models beyond sample
generation. The code is available at
\url{https://github.com/Adamdad/Repfusion}.Comment: Accepted by ICCV 202
Patterns of selective constraints in noncoding DNA of rice
<p>Abstract</p> <p>Background</p> <p>Several studies have investigated the relationships between selective constraints in introns and their length, GC content and location within genes. To date, however, no such investigation has been done in plants. Studies of selective constraints in noncoding DNA have generally involved interspecific comparisons, under the assumption of the same selective pressures acting in each lineage. Such comparisons are limited to cases in which the noncoding sequences are not too strongly diverged so that reliable sequence alignments can be obtained. Here, we investigate selective constraints in a recent segmental duplication that includes 605 paralogous intron pairs that occurred about 7 million years ago in rice (<it>O. sativa</it>).</p> <p>Results</p> <p>Our principal findings are: (1) intronic divergence is negatively correlated with intron length, a pattern that has previously been described in <it>Drosophila </it>and mammals; (2) there is a signature of strong purifying selection at splice control sites; (3) first introns are significantly longer and have a higher GC content than other introns; (4) the divergences of first and non-first introns are not significantly different from one another, a pattern that differs from <it>Drosophila </it>and mammals; and (5) short introns are more diverged than four-fold degenerate sites suggesting that selection reduces divergence at four-fold sites.</p> <p>Conclusion</p> <p>Our observation of stronger selective constraints in long introns suggests that functional elements subject to purifying selection may be concentrated within long introns. Our results are consistent with the presence of strong purifying selection at splicing control sites. Selective constraints are not significantly stronger in first introns of rice, as they are in other species.</p
Similarity-Aware Multimodal Prompt Learning for Fake News Detection
The standard paradigm for fake news detection mainly utilizes text
information to model the truthfulness of news. However, the discourse of online
fake news is typically subtle and it requires expert knowledge to use textual
information to debunk fake news. Recently, studies focusing on multimodal fake
news detection have outperformed text-only methods. Recent approaches utilizing
the pre-trained model to extract unimodal features, or fine-tuning the
pre-trained model directly, have become a new paradigm for detecting fake news.
Again, this paradigm either requires a large number of training instances, or
updates the entire set of pre-trained model parameters, making real-world fake
news detection impractical. Furthermore, traditional multimodal methods fuse
the cross-modal features directly without considering that the uncorrelated
semantic representation might inject noise into the multimodal features. This
paper proposes a Similarity-Aware Multimodal Prompt Learning (SAMPLE)
framework. First, we incorporate prompt learning into multimodal fake news
detection. Prompt learning, which only tunes prompts with a frozen language
model, can reduce memory usage significantly and achieve comparable
performances, compared with fine-tuning. We analyse three prompt templates with
a soft verbalizer to detect fake news. In addition, we introduce the
similarity-aware fusing method to adaptively fuse the intensity of multimodal
representation and mitigate the noise injection via uncorrelated cross-modal
features. For evaluation, SAMPLE surpasses the F1 and the accuracies of
previous works on two benchmark multimodal datasets, demonstrating the
effectiveness of the proposed method in detecting fake news. In addition,
SAMPLE also is superior to other approaches regardless of few-shot and
data-rich settings
A Note on the Generative Power of Axon P Systems
Axon P systems are a class of spiking neural P systems. In this paper, the axon P systems are used as number generators and language generators. As a language generator, the relationships of the families of languages generated by axon P systems with finite and context-free languages are considered. As a number generator, a characterization of the family of finite sets can be obtained by axon P systems with only one node. The relationships of sets of numbers generated by axon P systems with semilinear sets of numbers are also investigated. This paper partially answers some open problems formulated by H. Chen, T.-O. Ishdorj and Gh. Păun
SymmNeRF: Learning to Explore Symmetry Prior for Single-View View Synthesis
We study the problem of novel view synthesis of objects from a single image.
Existing methods have demonstrated the potential in single-view view synthesis.
However, they still fail to recover the fine appearance details, especially in
self-occluded areas. This is because a single view only provides limited
information. We observe that manmade objects usually exhibit symmetric
appearances, which introduce additional prior knowledge. Motivated by this, we
investigate the potential performance gains of explicitly embedding symmetry
into the scene representation. In this paper, we propose SymmNeRF, a neural
radiance field (NeRF) based framework that combines local and global
conditioning under the introduction of symmetry priors. In particular, SymmNeRF
takes the pixel-aligned image features and the corresponding symmetric features
as extra inputs to the NeRF, whose parameters are generated by a hypernetwork.
As the parameters are conditioned on the image-encoded latent codes, SymmNeRF
is thus scene-independent and can generalize to new scenes. Experiments on
synthetic and real-world datasets show that SymmNeRF synthesizes novel views
with more details regardless of the pose transformation, and demonstrates good
generalization when applied to unseen objects. Code is available at:
https://github.com/xingyi-li/SymmNeRF.Comment: Accepted by ACCV 202
Selection and mutation on microRNA target sequences during rice evolution
<p>Abstract</p> <p>Background</p> <p>MicroRNAs (miRNAs) posttranscriptionally down-regulate gene expression by binding target mRNAs. Analysis of the evolution of miRNA binding sites is helpful in understanding the co-evolution between miRNAs and their targets. To understand this process in plants a comparative analysis of miRNA-targeted duplicated gene pairs derived from a well-documented whole genome duplication (WGD) event in combination with a population genetics study of six experimentally validated miRNA binding sites in rice (<it>O. sativa</it>) was carried out.</p> <p>Results</p> <p>Of the 1,331 pairs of duplicate genes from the WGD, 41 genes (29 pairs) were computationally predicted to be miRNA targets. Sequence substitution analysis indicated that the synonymous substitution rate was significantly lower in the miRNA binding sites than their 5' and 3' flanking regions. Of the 29 duplicated gene pairs, 17 have only one paralog been targeted by a miRNA. This could be due to either gain of a miRNA binding site after the WGD or because one of the duplicated genes has escaped from being a miRNA target after the WGD (loss of miRNA binding site). These possibilities were distinguished by separating miRNAs conserved in both dicots and monocot plants from rice-specific miRNAs and by phylogenetic analysis of miRNA target gene families. The gain/loss rate of miRNA binding sites was estimated to be 3.0 × 10<sup>-9 </sup>gain/loss per year. Most (70.6%) of the gains/losses were due to nucleotide mutation. By analysis of cultivated (<it>O. sativa</it>; <it>n </it>= 30) and wild (<it>O. rufipogon</it>; <it>n </it>= 15) rice populations, no segregating site was observed in six miRNA binding sites whereas 0.12–0.20 SNPs per 21-nt or 1.53–1.80 × 10<sup>-3 </sup>of the average pairwise nucleotide diversity (π) were found in their flanking regions.</p> <p>Conclusion</p> <p>Both molecular evolution and population genetics support the hypothesis that conservation of miRNA binding sites is maintained by purifying selection through elimination of deleterious alleles. Nucleotide mutations play a major role in the gain/loss of miRNA binding sites during evolution.</p
Towards Personalized Federated Learning via Heterogeneous Model Reassembly
This paper focuses on addressing the practical yet challenging problem of
model heterogeneity in federated learning, where clients possess models with
different network structures. To track this problem, we propose a novel
framework called pFedHR, which leverages heterogeneous model reassembly to
achieve personalized federated learning. In particular, we approach the problem
of heterogeneous model personalization as a model-matching optimization task on
the server side. Moreover, pFedHR automatically and dynamically generates
informative and diverse personalized candidates with minimal human
intervention. Furthermore, our proposed heterogeneous model reassembly
technique mitigates the adverse impact introduced by using public data with
different distributions from the client data to a certain extent. Experimental
results demonstrate that pFedHR outperforms baselines on three datasets under
both IID and Non-IID settings. Additionally, pFedHR effectively reduces the
adverse impact of using different public data and dynamically generates diverse
personalized models in an automated manner
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