14 research outputs found
Goal-oriented Dialogue Policy Learning from Failures
Reinforcement learning methods have been used for learning dialogue policies.
However, learning an effective dialogue policy frequently requires
prohibitively many conversations. This is partly because of the sparse rewards
in dialogues, and the very few successful dialogues in early learning phase.
Hindsight experience replay (HER) enables learning from failures, but the
vanilla HER is inapplicable to dialogue learning due to the implicit goals. In
this work, we develop two complex HER methods providing different trade-offs
between complexity and performance, and, for the first time, enabled HER-based
dialogue policy learning. Experiments using a realistic user simulator show
that our HER methods perform better than existing experience replay methods (as
applied to deep Q-networks) in learning rate
SourceP: Smart Ponzi Schemes Detection on Ethereum Using Pre-training Model with Data Flow
As blockchain technology becomes more and more popular, a typical financial
scam, the Ponzi scheme, has also emerged in the blockchain platform Ethereum.
This Ponzi scheme deployed through smart contracts, also known as the smart
Ponzi scheme, has caused a lot of economic losses and negative impacts.
Existing methods for detecting smart Ponzi schemes on Ethereum mainly rely on
bytecode features, opcode features, account features, and transaction behavior
features of smart contracts, and such methods lack interpretability and
sustainability. In this paper, we propose SourceP, a method to detect smart
Ponzi schemes on the Ethereum platform using pre-training models and data flow,
which only requires using the source code of smart contracts as features to
explore the possibility of detecting smart Ponzi schemes from another
direction. SourceP reduces the difficulty of data acquisition and feature
extraction of existing detection methods while increasing the interpretability
of the model. Specifically, we first convert the source code of a smart
contract into a data flow graph and then introduce a pre-training model based
on learning code representations to build a classification model to identify
Ponzi schemes in smart contracts. The experimental results show that SourceP
achieves 87.2\% recall and 90.7\% F-score for detecting smart Ponzi schemes
within Ethereum's smart contract dataset, outperforming state-of-the-art
methods in terms of performance and sustainability. We also demonstrate through
additional experiments that pre-training models and data flow play an important
contribution to SourceP, as well as proving that SourceP has a good
generalization ability.Comment: 12 page
Learning and Reasoning for Robot Dialog and Navigation Tasks
You are viewing an article from the Proceedings of the 21st Annual Meeting of the Special Interest Group on Discourse and Dialogue that was in the Good Systems Network Digest in 2020.Office of the VP for Researc
Efficient Dialog Policy Learning by Reasoning with Contextual Knowledge
Goal-oriented dialog policy learning algorithms aim to learn a dialog policy for selecting language actions based on the current dialog state. Deep reinforcement learning methods have been used for dialog policy learning. This work is motivated by the observation that, although dialog is a domain with rich contextual knowledge, reinforcement learning methods are ill-equipped to incorporate such knowledge into the dialog policy learning process. In this paper, we develop a deep reinforcement learning framework for goal-oriented dialog policy learning that learns user preferences from user goal data, while leveraging commonsense knowledge from people. The developed framework has been evaluated using a realistic dialog simulation platform. Compared with baselines from the literature and the ablations of our approach, we see significant improvements in learning efficiency and the quality of the computed action policies
CcpA Regulates <i>Staphylococcus aureus</i> Biofilm Formation through Direct Repression of Staphylokinase Expression
Staphylococcus aureus represents a notorious opportunistic pathogen causing various infections in biofilm nature, imposing remarkable therapeutic challenges worldwide. The catabolite control protein A (CcpA), a major regulator of carbon catabolite repression (CCR), has been recognized to modulate S. aureus biofilm formation, while the underlying mechanism remains to be fully elucidated. In this study, the reduced biofilm was firstly determined in the ccpA deletion mutant of S. aureus clinical isolate XN108 using both crystal violet staining and confocal laser scanning microscopy. RNA-seq analysis suggested that sak-encoding staphylokinase (Sak) was significantly upregulated in the mutant ∆ccpA, which was further confirmed by RT-qPCR. Consistently, the induced Sak production correlated the elevated promoter activity of sak and increased secretion in the supernatants, as demonstrated by Psak-lacZ reporter fusion expression and chromogenic detection, respectively. Notably, electrophoretic mobility shift assays showed that purified recombinant protein CcpA binds directly to the promoter region of sak, suggesting the direct negative control of sak expression by CcpA. Double isogenic deletion of ccpA and sak restored biofilm formation for mutant ∆ccpA, which could be diminished by trans-complemented sak. Furthermore, the exogenous addition of recombinant Sak inhibited biofilm formation for XN108 in a dose-dependent manner. Together, this study delineates a novel model of CcpA-controlled S. aureus biofilm through direct inhibition of sak expression, highlighting the multifaceted roles and multiple networks regulated by CcpA
Bioinspired Coordination Micelles Integrating High Stability, Triggered Cargo Release, and Magnetic Resonance Imaging
Catechol-Fe<sup>3+</sup> coordinated micelles show the potential for achieving on-demand
drug delivery and magnetic resonance imaging in a single nanoplatform.
Herein, we developed bioinspired coordination-cross-linked amphiphilic
polymeric micelles loaded with a model anticancer agent, doxorubicin
(Dox). The nanoscale micelles could tolerate substantial dilution
to a condition below the critical micelle concentration (9.4 ±
0.3 μg/mL) without sacrificing the nanocarrier integrity due
to the catechol-Fe<sup>3+</sup> coordinated core cross-linking. Under
acidic conditions (pH 5.0), the release rate of Dox was significantly
faster compared to that at pH 7.4 as a consequence of coordination
collapse and particle de-cross-linking. The cell viability study in
4T1 cells showed no toxicity regarding placebo cross-linked micelles.
The micelles with improved stability showed a dramatically increased
Dox accumulation in tumors and hence the enhanced suppression of tumor
growth in a 4T1 tumor-bearing mouse model. The presence of Fe<sup>3+</sup> endowed the micelles <i>T</i><sub>1</sub>-weighted
MRI capability both in vitro and in vivo without the incorporation
of traditional toxic paramagnetic contrast agents. The current work
presented a simple “three birds with one stone” approach
to engineer the robust theranostic nanomedicine platform