1,158 research outputs found
DramaQA: Character-Centered Video Story Understanding with Hierarchical QA
Despite recent progress on computer vision and natural language processing,
developing video understanding intelligence is still hard to achieve due to the
intrinsic difficulty of story in video. Moreover, there is not a theoretical
metric for evaluating the degree of video understanding. In this paper, we
propose a novel video question answering (Video QA) task, DramaQA, for a
comprehensive understanding of the video story. The DramaQA focused on two
perspectives: 1) hierarchical QAs as an evaluation metric based on the
cognitive developmental stages of human intelligence. 2) character-centered
video annotations to model local coherence of the story. Our dataset is built
upon the TV drama "Another Miss Oh" and it contains 16,191 QA pairs from 23,928
various length video clips, with each QA pair belonging to one of four
difficulty levels. We provide 217,308 annotated images with rich
character-centered annotations, including visual bounding boxes, behaviors, and
emotions of main characters, and coreference resolved scripts. Additionally, we
provide analyses of the dataset as well as Dual Matching Multistream model
which effectively learns character-centered representations of video to answer
questions about the video. We are planning to release our dataset and model
publicly for research purposes and expect that our work will provide a new
perspective on video story understanding research.Comment: 21 pages, 10 figures, submitted to ECCV 202
Mitochondrial function contributes to oxysterol-induced osteogenic differentiation in mouse embryonic stem cells
AbstractOxysterols, oxidized derivatives of cholesterol, are biologically active molecules. Specific oxysterols have potent osteogenic properties that act on osteoprogenitor cells. However, the molecular mechanisms underlying these osteoinductive effects on embryonic stem cells (ESCs) are unknown. This study investigated the effect of an oxysterol combination of 22(S)-hydroxycholesterol and 20(S)-hydroxycholesterol (SS) on osteogenic differentiation of ESCs and the alterations to mitochondrial activity during differentiation. Osteogenic differentiation was assessed by alkaline phosphatase (ALP) activity, matrix mineralization, mRNA expression of osteogenic factors, runt-related transcription factor 2, osterix, and osteocalcin, and protein levels of collagen type IA (COLIA) and osteopontin (OPN). Treatment of cells with SS increased osteoinductive activity compared to the control group. Intracellular reactive oxygen species production, intracellular ATP content, mitochondrial membrane potential, mitochondrial mass, mitochondrial DNA copy number, and mRNA expression of peroxisome proliferator-activated receptor-γ coactivators 1α and β, transcription factors involved in mitochondrial biogenesis, were significantly increased during osteogenesis, indicating upregulation of mitochondrial activity. Oxysterol combinations also increased protein levels of mitochondrial respiratory complexes I–V. We also found that SS treatment increased hedgehog signaling target genes, Smo and Gli1 expression. Inhibition of Hh signaling by cyclopamine suppressed mitochondrial biogenesis and ESC osteogenesis. Subsequently, oxysterol-induced Wnt/β-catenin pathways were inhibited by repression of Hh signaling and mitochondrial biogenesis. Transfection of β-catenin specific siRNA decreased the protein levels of COLIA and OPN, as well as ALP activity. Collectively, these data suggest that lipid-based oxysterols enhance differentiation of ESCs toward the osteogenic lineage by regulating mitochondrial activity, canonical Hh/Gli, and Wnt/β-catenin signaling
Cut-Based Graph Learning Networks to Discover Compositional Structure of Sequential Video Data
Conventional sequential learning methods such as Recurrent Neural Networks
(RNNs) focus on interactions between consecutive inputs, i.e. first-order
Markovian dependency. However, most of sequential data, as seen with videos,
have complex dependency structures that imply variable-length semantic flows
and their compositions, and those are hard to be captured by conventional
methods. Here, we propose Cut-Based Graph Learning Networks (CB-GLNs) for
learning video data by discovering these complex structures of the video. The
CB-GLNs represent video data as a graph, with nodes and edges corresponding to
frames of the video and their dependencies respectively. The CB-GLNs find
compositional dependencies of the data in multilevel graph forms via a
parameterized kernel with graph-cut and a message passing framework. We
evaluate the proposed method on the two different tasks for video
understanding: Video theme classification (Youtube-8M dataset) and Video
Question and Answering (TVQA dataset). The experimental results show that our
model efficiently learns the semantic compositional structure of video data.
Furthermore, our model achieves the highest performance in comparison to other
baseline methods.Comment: 8 pages, 3 figures, Association for the Advancement of Artificial
Intelligence (AAAI2020). arXiv admin note: substantial text overlap with
arXiv:1907.0170
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