945 research outputs found
Auditor-Client Disagreements, Auditor Resignations, And Audit Fees Charged By Successor Auditors
This paper investigates the effects of auditor-client disagreement disclosure on auditor resignations and audit fee charged by successor auditors. Using a matched sample of auditor changes over the period 2003-2016, we find that auditor resignations are more often accompanied by auditor-client disagreements. We also find that Big 4 auditors are more likely to resign from their engagements when they disagree with their clients. Further, we document that successor auditors charge higher audit fees for firms that have disagreements with their predecessor auditors. Relative to non-Big 4 auditors, Big 4 successor auditors charge even higher audit fee for disagreement firms
Improved critical current densities in MgB2 tapes with ZrB2 doping
MgB2/Fe tapes with 2.5-15 at.% ZrB2 additions were prepared through the in
situ powder-in-tube method. Compared to the pure tape, a significant
improvement in the in-field critical current density Jc was observed, most
notably for 10 at.% doping, while the critical temperature decreased slightly.
At 4.2 K, the transport Jc for the 10 at.% doped sample increased by more than
an order of magnitude than the undoped one in magnetic fields above 9 T.
Nanoscale segregates or defects caused by the ZrB2 additions which act as
effective flux pinning centers are proposed to be the main reason for the
improved Jc field performance.Comment: 14 pages, 6 figure
RESEARCH ON THE FLUID-INDUCED EXCITATION CHARACTERISTICS OF THE CENTRIFUGAL PUMP CONSIDERING THE COMPOUND WHIRL EFFECT
In order to study the correlation mechanism between the flow characteristics and the fluid-induced force under the compound whirl motion in the centrifugal pump, the RNG k-ε model is selected in this paper to simulate a low specific speed centrifugal pump with impeller eccentricity based on the N-S equation. The changes of fluid-induced force with impeller eccentricity and the unsteady flow characteristics of the internal flow field of centrifugal pump under different flow conditions and rotation speeds are investigated, and the relationship between the fluid-induced force of the impeller and the internal flow field characteristics is discussed. The results show that the trend of fluid-induced force and the pressure coefficient is similar. When the rotation speed changes and when the flow is similar, the pressure coefficient under different rotation speeds almost coincides. With the increase of impeller speed and impeller eccentricity, the dynamic and static interferences between the impeller and the volute tongue are more significant, the uneven distribution of the pressure around the impeller makes the internal flow of centrifugal pump more disordered and increases the fluid-induced force near the volute tongue. The research results can provide important reference value for accurately grasping the internal flow excitation principle of the centrifugal pump
Indoor simultaneous localization and mapping based on fringe projection profilometry
Simultaneous Localization and Mapping (SLAM) plays an important role in
outdoor and indoor applications ranging from autonomous driving to indoor
robotics. Outdoor SLAM has been widely used with the assistance of LiDAR or
GPS. For indoor applications, the LiDAR technique does not satisfy the accuracy
requirement and the GPS signals will be lost. An accurate and efficient scene
sensing technique is required for indoor SLAM. As the most promising 3D sensing
technique, the opportunities for indoor SLAM with fringe projection
profilometry (FPP) systems are obvious, but methods to date have not fully
leveraged the accuracy and speed of sensing that such systems offer. In this
paper, we propose a novel FPP-based indoor SLAM method based on the coordinate
transformation relationship of FPP, where the 2D-to-3D descriptor-assisted is
used for mapping and localization. The correspondences generated by matching
descriptors are used for fast and accurate mapping, and the transform
estimation between the 2D and 3D descriptors is used to localize the sensor.
The provided experimental results demonstrate that the proposed indoor SLAM can
achieve the localization and mapping accuracy around one millimeter
Trustworthy Representation Learning Across Domains
As AI systems have obtained significant performance to be deployed widely in
our daily live and human society, people both enjoy the benefits brought by
these technologies and suffer many social issues induced by these systems. To
make AI systems good enough and trustworthy, plenty of researches have been
done to build guidelines for trustworthy AI systems. Machine learning is one of
the most important parts for AI systems and representation learning is the
fundamental technology in machine learning. How to make the representation
learning trustworthy in real-world application, e.g., cross domain scenarios,
is very valuable and necessary for both machine learning and AI system fields.
Inspired by the concepts in trustworthy AI, we proposed the first trustworthy
representation learning across domains framework which includes four concepts,
i.e, robustness, privacy, fairness, and explainability, to give a comprehensive
literature review on this research direction. Specifically, we first introduce
the details of the proposed trustworthy framework for representation learning
across domains. Second, we provide basic notions and comprehensively summarize
existing methods for the trustworthy framework from four concepts. Finally, we
conclude this survey with insights and discussions on future research
directions.Comment: 38 pages, 15 figure
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Structural basis for DNMT3A-mediated de novo DNA methylation.
DNA methylation by de novo DNA methyltransferases 3A (DNMT3A) and 3B (DNMT3B) at cytosines is essential for genome regulation and development. Dysregulation of this process is implicated in various diseases, notably cancer. However, the mechanisms underlying DNMT3 substrate recognition and enzymatic specificity remain elusive. Here we report a 2.65-ångström crystal structure of the DNMT3A-DNMT3L-DNA complex in which two DNMT3A monomers simultaneously attack two cytosine-phosphate-guanine (CpG) dinucleotides, with the target sites separated by 14 base pairs within the same DNA duplex. The DNMT3A-DNA interaction involves a target recognition domain, a catalytic loop, and DNMT3A homodimeric interface. Arg836 of the target recognition domain makes crucial contacts with CpG, ensuring DNMT3A enzymatic preference towards CpG sites in cells. Haematological cancer-associated somatic mutations of the substrate-binding residues decrease DNMT3A activity, induce CpG hypomethylation, and promote transformation of haematopoietic cells. Together, our study reveals the mechanistic basis for DNMT3A-mediated DNA methylation and establishes its aetiological link to human disease
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