107 research outputs found
rac-tert-Butyl 2-{5-[(4-{2-[methyl(pyriÂdin-2-yl)amino]ethoxy}phenyl)methyl]-2,4-dioxo-1,3-thiazolidin-3-yl}acetate
The title compound, C24H29N3O5S, is a chiral molÂecule which crystallizes in a centrosymmetric space group as a racemate. The thiaÂzolidine ring forms the dihedral angles of 29.22 (12) and 67.79 (10)° with the benzene and pyridine rings, respectively. The benzene and pyridine rings are tilted by dihedral angle of 67.18 (9)°. In the crystal, interÂmolecular C—H⋯O hydrogen bonds link the molÂecules into a two-dimensional network
Novel Design and Adaptive Fuzzy Control of a Lower-Limb Elderly Rehabilitation
Design and control of a lower-limb exoskeleton rehabilitation of the elderly are the main challenge for health care in the past decades. In order to satisfy the requirements of the elderly or disabled users, this paper presents a novel design and adaptive fuzzy control of lower-limb empowered rehabilitation, namely MOVING UP. Different from other rehabilitation devices, this article considers active rehabilitation training devices. Firstly, a novel product design method based on user experience is proposed for the lower-limb elderly exoskeleton rehabilitation. At the same time, in order to achieve a stable operation control for the assistant rehabilitation system, an adaptive fuzzy control scheme is discussed. Finally, the feasibility of the design and control method is validated with a detailed simulation study and the human-interaction test. With the booming demand in the global market for the assistive lower-limb exoskeleton, the methodology developed in this paper will bring more research and manufacturing interests
Rethinking Missing Data: Aleatoric Uncertainty-Aware Recommendation
Historical interactions are the default choice for recommender model
training, which typically exhibit high sparsity, i.e., most user-item pairs are
unobserved missing data. A standard choice is treating the missing data as
negative training samples and estimating interaction likelihood between
user-item pairs along with the observed interactions. In this way, some
potential interactions are inevitably mislabeled during training, which will
hurt the model fidelity, hindering the model to recall the mislabeled items,
especially the long-tail ones. In this work, we investigate the mislabeling
issue from a new perspective of aleatoric uncertainty, which describes the
inherent randomness of missing data. The randomness pushes us to go beyond
merely the interaction likelihood and embrace aleatoric uncertainty modeling.
Towards this end, we propose a new Aleatoric Uncertainty-aware Recommendation
(AUR) framework that consists of a new uncertainty estimator along with a
normal recommender model. According to the theory of aleatoric uncertainty, we
derive a new recommendation objective to learn the estimator. As the chance of
mislabeling reflects the potential of a pair, AUR makes recommendations
according to the uncertainty, which is demonstrated to improve the
recommendation performance of less popular items without sacrificing the
overall performance. We instantiate AUR on three representative recommender
models: Matrix Factorization (MF), LightGCN, and VAE from mainstream model
architectures. Extensive results on two real-world datasets validate the
effectiveness of AUR w.r.t. better recommendation results, especially on
long-tail items
Mining Unfollow Behavior in Large-Scale Online Social Networks via Spatial-Temporal Interaction
Online Social Networks (OSNs) evolve through two pervasive behaviors: follow
and unfollow, which respectively signify relationship creation and relationship
dissolution. Researches on social network evolution mainly focus on the follow
behavior, while the unfollow behavior has largely been ignored. Mining unfollow
behavior is challenging because user's decision on unfollow is not only
affected by the simple combination of user's attributes like informativeness
and reciprocity, but also affected by the complex interaction among them.
Meanwhile, prior datasets seldom contain sufficient records for inferring such
complex interaction. To address these issues, we first construct a large-scale
real-world Weibo dataset, which records detailed post content and relationship
dynamics of 1.8 million Chinese users. Next, we define user's attributes as two
categories: spatial attributes (e.g., social role of user) and temporal
attributes (e.g., post content of user). Leveraging the constructed dataset, we
systematically study how the interaction effects between user's spatial and
temporal attributes contribute to the unfollow behavior. Afterwards, we propose
a novel unified model with heterogeneous information (UMHI) for unfollow
prediction. Specifically, our UMHI model: 1) captures user's spatial attributes
through social network structure; 2) infers user's temporal attributes through
user-posted content and unfollow history; and 3) models the interaction between
spatial and temporal attributes by the nonlinear MLP layers. Comprehensive
evaluations on the constructed dataset demonstrate that the proposed UMHI model
outperforms baseline methods by 16.44% on average in terms of precision. In
addition, factor analyses verify that both spatial attributes and temporal
attributes are essential for mining unfollow behavior.Comment: 8 pages, 7 figures, Accepted by AAAI 202
TransRec: Learning Transferable Recommendation from Mixture-of-Modality Feedback
Learning large-scale pre-trained models on broad-ranging data and then
transfer to a wide range of target tasks has become the de facto paradigm in
many machine learning (ML) communities. Such big models are not only strong
performers in practice but also offer a promising way to break out of the
task-specific modeling restrictions, thereby enabling task-agnostic and unified
ML systems. However, such a popular paradigm is mainly unexplored by the
recommender systems (RS) community. A critical issue is that standard
recommendation models are primarily built on categorical identity features.
That is, the users and the interacted items are represented by their unique
IDs, which are generally not shareable across different systems or platforms.
To pursue the transferable recommendations, we propose studying pre-trained RS
models in a novel scenario where a user's interaction feedback involves a
mixture-of-modality (MoM) items, e.g., text and images. We then present
TransRec, a very simple modification made on the popular ID-based RS framework.
TransRec learns directly from the raw features of the MoM items in an
end-to-end training manner and thus enables effective transfer learning under
various scenarios without relying on overlapped users or items. We empirically
study the transferring ability of TransRec across four different real-world
recommendation settings. Besides, we look at its effects by scaling source and
target data size. Our results suggest that learning neural recommendation
models from MoM feedback provides a promising way to realize universal RS
Gene Expression Analysis Reveals Novel Gene Signatures Between Young and Old Adults in Human Prefrontal Cortex
Human neurons function over an entire lifetime, yet the molecular mechanisms which perform their functions and protecting against neurodegenerative disease during aging are still elusive. Here, we conducted a systematic study on the human brain aging by using the weighted gene correlation network analysis (WGCNA) method to identify meaningful modules or representative biomarkers for human brain aging. Significantly, 19 distinct gene modules were detected based on the dataset GSE53890; among them, six modules related to the feature of brain aging were highly preserved in diverse independent datasets. Interestingly, network feature analysis confirmed that the blue modules demonstrated a remarkably correlation with human brain aging progress. Besides, the top hub genes including PPP3CB, CAMSAP1, ACTR3B, and GNG3 were identified and characterized by high connectivity, module membership, or gene significance in the blue module. Furthermore, these genes were validated in mice of different ages. Mechanically, the potential regulators of blue module were investigated. These findings highlight an important role of the blue module and its affiliated genes in the control of normal brain aging, which may lead to potential therapeutic interventions for brain aging by targeting the hub genes
An efficient synthesis of Vildagliptin intermediates
Efficient and high yielding methods for the preparation of vildagliptin 1 intermediate of (S)-1-(2-chloroacetyl) pyrrolidine-2-carbonitrile 2 and 3-amino-1-adamantane alcohol 3 respectively have been described. (S)-1-(2-Chloroacetyl) pyrrolidine-2-carbonitrile 2 has been synthesized from l-proline 2a via chloroacetyl chloride, performed with acetonitrile in the presence of sulfuric acid via one-pot reactions. 3-Amino-1-adamantane alcohol 3 has been prepared from amantadine hydrochloride via oxidation by sulfuric acid/nitric acid and boric acid as catalyst, and has been subjected to ethanol extraction. The overall yield is about 95%.
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