76 research outputs found
An Iterative Learning Algorithm for Deciphering Stegoscripts: a Grammatical Approach for Motif Discovery
Steganography, or information hiding, is to conceal the existence of messages so as to protect their confidentiality. We consider de-ciphering a stegoscript, a text with secret messages embedded within a covertext, and identifying the vocabularies used in the mes-sages, with no knowledge of the vocabularies and grammar in which the script was writ-ten. Our research was motivated by the prob-lem of identifying conserved non-coding func-tional elements (motifs) in regulatory regions of genome sequences, which we view as stego-scripts constructed by nature with a statis-tical model consisting of a dictionary and a grammar. We develop an iterative learning algorithm, WordSpy, to learn such a model from a stegoscript. The model then can be applied to identify the embedded secret mes-sages, i.e., the functional motifs. Our algo-rithm can successfully recover the most pos-sible text of the first ten chapters of a novel embedded in a stegoscript and identify the transcription factor binding motifs in the up-stream regions of ∼ 800 yeast genes
A steganalysis-based approach to comprehensive identification and characterization of functional regulatory elements
The comprehensive identification of cis-regulatory elements on a genome scale is a challenging problem. We develop a novel, steganalysis-based approach for genome-wide motif finding, called WordSpy, by viewing regulatory regions as a stegoscript with cis-elements embedded in 'background' sequences. We apply WordSpy to the promoters of cell-cycle-related genes of Saccharomyces cerevisiae and Arabidopsis thaliana, identifying all known cell-cycle motifs with high ranking. WordSpy can discover a complete set of cis-elements and facilitate the systematic study of regulatory networks
UV-B responsive microRNA genes in Arabidopsis thaliana
MicroRNAs (miRNAs) are small, non-coding RNAs that play critical roles in post-transcriptional gene regulation. In plants, mature miRNAs pair with complementary sites on mRNAs and subsequently lead to cleavage and degradation of the mRNAs. Many miRNAs target mRNAs that encode transcription factors; therefore, they regulate the expression of many downstream genes. In this study, we carry out a survey of Arabidopsis microRNA genes in response to UV-B radiation, an important adverse abiotic stress. We develop a novel computational approach to identify microRNA genes induced by UV-B radiation and characterize their functions in regulating gene expression. We report that in A. thaliana, 21 microRNA genes in 11 microRNA families are upregulated under UV-B stress condition. We also discuss putative transcriptional downregulation pathways triggered by the induction of these microRNA genes. Moreover, our approach can be directly applied to miRNAs responding to other abiotic and biotic stresses and extended to miRNAs in other plants and metazoans
WordSpy: identifying transcription factor binding motifs by building a dictionary and learning a grammar
Transcription factor (TF) binding sites or motifs (TFBMs) are functional cis-regulatory DNA sequences that play an essential role in gene transcriptional regulation. Although many experimental and computational methods have been developed, finding TFBMs remains a challenging problem. We propose and develop a novel dictionary based motif finding algorithm, which we call WordSpy. One significant feature of WordSpy is the combination of a word counting method and a statistical model which consists of a dictionary of motifs and a grammar specifying their usage. The algorithm is suitable for genome-wide motif finding; it is capable of discovering hundreds of motifs from a large set of promoters in a single run. We further enhance WordSpy by applying gene expression information to separate true TFBMs from spurious ones, and by incorporating negative sequences to identify discriminative motifs. In addition, we also use randomly selected promoters from the genome to evaluate the significance of the discovered motifs. The output from WordSpy consists of an ordered list of putative motifs and a set of regulatory sequences with motif binding sites highlighted. The web server of WordSpy is available at
Reinforced Path Reasoning for Counterfactual Explainable Recommendation
Counterfactual explanations interpret the recommendation mechanism via
exploring how minimal alterations on items or users affect the recommendation
decisions. Existing counterfactual explainable approaches face huge search
space and their explanations are either action-based (e.g., user click) or
aspect-based (i.e., item description). We believe item attribute-based
explanations are more intuitive and persuadable for users since they explain by
fine-grained item demographic features (e.g., brand). Moreover, counterfactual
explanation could enhance recommendations by filtering out negative items.
In this work, we propose a novel Counterfactual Explainable Recommendation
(CERec) to generate item attribute-based counterfactual explanations meanwhile
to boost recommendation performance. Our CERec optimizes an explanation policy
upon uniformly searching candidate counterfactuals within a reinforcement
learning environment. We reduce the huge search space with an adaptive path
sampler by using rich context information of a given knowledge graph. We also
deploy the explanation policy to a recommendation model to enhance the
recommendation. Extensive explainability and recommendation evaluations
demonstrate CERec's ability to provide explanations consistent with user
preferences and maintain improved recommendations. We release our code at
https://github.com/Chrystalii/CERec
BLOCKCHAIN-BASED SOLUTIONS FOR HUMANITARIAN SUPPLY CHAIN MANAGEMENT
The outbreak of the novel COVID-19 demonstrates how pandemics disturb supply chains (SC) all across the world. Policymakers and private-sector partners are increasingly acknowledging that we cannot tackle today\u27s issues without leveraging the promise of new technology. Blockchain technology is increasingly being adopted to help humanitarian efforts in various fields. This paper presents conceptual research designed to assess how Blockchain distributed ledger technology can be leveraged to enhance humanitarian supply chain management (HSCM). This paper fills the present research gap on the Blockchain\u27s potential implications for HSCM by proposing a framework built on the foundations of five prominent institutional economic theories: social exchange theory, principal-agent theory, transaction cost theory, resource-based view, and network theory. These theories could be utilized to generate research topics that are theory-based and industry-relevant. This conceptual framework assists institutions in making decisions about how to recover and rebuild their SC during disasters
Counterfactual Explanation for Fairness in Recommendation
Fairness-aware recommendation eliminates discrimination issues to build
trustworthy recommendation systems.Explaining the causes of unfair
recommendations is critical, as it promotes fairness diagnostics, and thus
secures users' trust in recommendation models. Existing fairness explanation
methods suffer high computation burdens due to the large-scale search space and
the greedy nature of the explanation search process. Besides, they perform
score-based optimizations with continuous values, which are not applicable to
discrete attributes such as gender and race. In this work, we adopt the novel
paradigm of counterfactual explanation from causal inference to explore how
minimal alterations in explanations change model fairness, to abandon the
greedy search for explanations. We use real-world attributes from Heterogeneous
Information Networks (HINs) to empower counterfactual reasoning on discrete
attributes. We propose a novel Counterfactual Explanation for Fairness
(CFairER) that generates attribute-level counterfactual explanations from HINs
for recommendation fairness. Our CFairER conducts off-policy reinforcement
learning to seek high-quality counterfactual explanations, with an attentive
action pruning reducing the search space of candidate counterfactuals. The
counterfactual explanations help to provide rational and proximate explanations
for model fairness, while the attentive action pruning narrows the search space
of attributes. Extensive experiments demonstrate our proposed model can
generate faithful explanations while maintaining favorable recommendation
performance
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