84 research outputs found
GraLSP: Graph Neural Networks with Local Structural Patterns
It is not until recently that graph neural networks (GNNs) are adopted to
perform graph representation learning, among which, those based on the
aggregation of features within the neighborhood of a node achieved great
success. However, despite such achievements, GNNs illustrate defects in
identifying some common structural patterns which, unfortunately, play
significant roles in various network phenomena. In this paper, we propose
GraLSP, a GNN framework which explicitly incorporates local structural patterns
into the neighborhood aggregation through random anonymous walks. Specifically,
we capture local graph structures via random anonymous walks, powerful and
flexible tools that represent structural patterns. The walks are then fed into
the feature aggregation, where we design various mechanisms to address the
impact of structural features, including adaptive receptive radius, attention
and amplification. In addition, we design objectives that capture similarities
between structures and are optimized jointly with node proximity objectives.
With the adequate leverage of structural patterns, our model is able to
outperform competitive counterparts in various prediction tasks in multiple
datasets
The continuous-time pre-commitment KMM problem in incomplete markets
This paper studies the continuous-time pre-commitment KMM problem proposed by
Klibanoff, Marinacci and Mukerji (2005) in incomplete financial markets, which
concerns with the portfolio selection under smooth ambiguity. The decision
maker (DM) is uncertain about the dominated priors of the financial market,
which are characterized by a second-order distribution (SOD). The KMM model
separates risk attitudes and ambiguity attitudes apart and the aim of the DM is
to maximize the two-fold utility of terminal wealth, which does not belong to
the classical subjective utility maximization problem. By constructing the
efficient frontier, the original KMM problem is first simplified as an one-fold
expected utility problem on the second-order space. In order to solve the
equivalent simplified problem, this paper imposes an assumption and introduces
a new distorted Legendre transformation to establish the bipolar relation and
the distorted duality theorem. Then, under a further assumption that the
asymptotic elasticity of the ambiguous attitude is less than 1, the uniqueness
and existence of the solution to the KMM problem are shown and we obtain the
semi-explicit forms of the optimal terminal wealth and the optimal strategy.
Explicit forms of optimal strategies are presented for CRRA, CARA and HARA
utilities in the case of Gaussian SOD in a Black-Scholes financial market,
which show that DM with higher ambiguity aversion tends to be more concerned
about extreme market conditions with larger bias. In the end of this work,
numerical comparisons with the DMs ignoring ambiguity are revealed to
illustrate the effects of ambiguity on the optimal strategies and value
functions.Comment: 53 pages, 7 figure
Diffusion Policy: Visuomotor Policy Learning via Action Diffusion
This paper introduces Diffusion Policy, a new way of generating robot
behavior by representing a robot's visuomotor policy as a conditional denoising
diffusion process. We benchmark Diffusion Policy across 11 different tasks from
4 different robot manipulation benchmarks and find that it consistently
outperforms existing state-of-the-art robot learning methods with an average
improvement of 46.9%. Diffusion Policy learns the gradient of the
action-distribution score function and iteratively optimizes with respect to
this gradient field during inference via a series of stochastic Langevin
dynamics steps. We find that the diffusion formulation yields powerful
advantages when used for robot policies, including gracefully handling
multimodal action distributions, being suitable for high-dimensional action
spaces, and exhibiting impressive training stability. To fully unlock the
potential of diffusion models for visuomotor policy learning on physical
robots, this paper presents a set of key technical contributions including the
incorporation of receding horizon control, visual conditioning, and the
time-series diffusion transformer. We hope this work will help motivate a new
generation of policy learning techniques that are able to leverage the powerful
generative modeling capabilities of diffusion models. Code, data, and training
details will be publicly available
Dai-Huang-Fu-Zi-Tang Alleviates Intestinal Injury Associated with Severe Acute Pancreatitis by Regulating Mitochondrial Permeability Transition Pore of Intestinal Mucosa Epithelial Cells
Objective. The aim of the present study was to examine whether Dai-Huang-Fu-Zi-Tang (DHFZT) could regulate mitochondrial permeability transition pore (MPTP) of intestinal mucosa epithelial cells for alleviating intestinal injury associated with severe acute pancreatitis (SAP). Methods. A total of 72 Sprague-Dawley rats were randomly divided into 3 groups (sham group, SAP group, and DHFZT group, n=24 per group). The rats in each group were divided into 4 subgroups (n=6 per subgroup) accordingly at 1, 3, 6, and 12 h after the operation. The contents of serum amylase, D-lactic acid, diamine oxidase activity, and degree of MPTP were measured by dry chemical method and enzyme-linked immunosorbent assay. The change of mitochondria of intestinal epithelial cells was observed by transmission electron microscopy. Results. The present study showed that DHFZT inhibited the openness of MPTP at 3, 6, and 12 h after the operation. Meanwhile, it reduced the contents of serum D-lactic acid and activity of diamine oxidase activity and also drastically relieved histopathological manifestations and epithelial cells injury of intestine. Conclusion. DHFZT alleviates intestinal injury associated SAP via reducing the openness of MPTP. In addition, DHFZT could also decrease the content of serum diamine oxidase activity and D-lactic acid after SAP
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