450 research outputs found
Deep Item-based Collaborative Filtering for Top-N Recommendation
Item-based Collaborative Filtering(short for ICF) has been widely adopted in
recommender systems in industry, owing to its strength in user interest
modeling and ease in online personalization. By constructing a user's profile
with the items that the user has consumed, ICF recommends items that are
similar to the user's profile. With the prevalence of machine learning in
recent years, significant processes have been made for ICF by learning item
similarity (or representation) from data. Nevertheless, we argue that most
existing works have only considered linear and shallow relationship between
items, which are insufficient to capture the complicated decision-making
process of users.
In this work, we propose a more expressive ICF solution by accounting for the
nonlinear and higher-order relationship among items. Going beyond modeling only
the second-order interaction (e.g. similarity) between two items, we
additionally consider the interaction among all interacted item pairs by using
nonlinear neural networks. Through this way, we can effectively model the
higher-order relationship among items, capturing more complicated effects in
user decision-making. For example, it can differentiate which historical
itemsets in a user's profile are more important in affecting the user to make a
purchase decision on an item. We treat this solution as a deep variant of ICF,
thus term it as DeepICF. To justify our proposal, we perform empirical studies
on two public datasets from MovieLens and Pinterest. Extensive experiments
verify the highly positive effect of higher-order item interaction modeling
with nonlinear neural networks. Moreover, we demonstrate that by more
fine-grained second-order interaction modeling with attention network, the
performance of our DeepICF method can be further improved.Comment: 25 pages, submitted to TOI
Multi-region boundary element analysis and multi-layered Green's functions
This thesis aims to improve some aspects of the boundary element techniques in elastostatics and in particular its treatment of layered media. These include two areas of work: 1. The development of the partially discontinuous element method, that is, elements which are continuous on smooth boundaries but discontinuous at edges and comers, in order to address the well-known comer problem. This approach is relatively simple to implement whilst avoiding the computational disadvantages of discontinuous elements. We examine the effect of the offset distance between the free nodes and the element edges on accuracy and stability. This approach is implemented with automatic edge detection software, which incorporates partially discontinuous elements into BEM program without intervention by the user. This greatly reduces data preparation effort and makes the BEM an attractive option in practice. 2. In order to preserve the boundary-only discretization advantages of BEM, three-dimensional Green's functions in multi-layered systems are explored. These are computed using the cylindrical system of vector functions and the propagator matrix method. Numerical integration of these functions is problematic but a singularity extraction method is used to them accurately in the vicinity of the singularity. In this process, the Green's functions for the bi-material full space, are adopted instead of those for the homogeneous full space. The analytic work, which was necessary' to derive the necessary transformed functions in cylindrical vector space, is described in some detail. Numerical trials show that the current method is accurate and efficient, and superior to the previous approaches
A Systematic Evaluation of Federated Learning on Biomedical Natural Language Processing
Language models (LMs) like BERT and GPT have revolutionized natural language
processing (NLP). However, privacy-sensitive domains, particularly the medical
field, face challenges to train LMs due to limited data access and privacy
constraints imposed by regulations like the Health Insurance Portability and
Accountability Act (HIPPA) and the General Data Protection Regulation (GDPR).
Federated learning (FL) offers a decentralized solution that enables
collaborative learning while ensuring the preservation of data privacy. In this
study, we systematically evaluate FL in medicine across biomedical NLP
tasks using LMs encompassing corpora. Our results showed that: 1) FL
models consistently outperform LMs trained on individual client's data and
sometimes match the model trained with polled data; 2) With the fixed number of
total data, LMs trained using FL with more clients exhibit inferior
performance, but pre-trained transformer-based models exhibited greater
resilience. 3) LMs trained using FL perform nearly on par with the model
trained with pooled data when clients' data are IID distributed while
exhibiting visible gaps with non-IID data. Our code is available at:
https://github.com/PL97/FedNLPComment: Accepted by KDD 2023 Workshop FL4Data-Minin
Nitrogen, Cobalt Co-doped Fluorescent Magnetic Carbon Dots as Ratiometric Fluorescent Probes for Cholesterol and Uric Acid in Human Blood Serum
Detection of cholesterol and uric acid biomarkers is of great importance for clinical diagnosis of several serious diseases correlated with their variations in human blood serum. In this study, a new kind of well selective and highly sensitive ratiometric fluorescent probe for cholesterol and uric acid determination in human blood serum was innovatively developed on the basis of the inner filter effect (IFE) process of nitrogen, cobalt co-doped carbon dots (N,Co-CDs) with 2,3-diaminophenazine (DAP). DAP was the oxidative product during the oxidation reaction between ophenylenediamine and H2O2. Fluorescent magnetic N,Co-CDs possessing blue emission and magnetic property were prepared through a facile one-pot hydrothermal strategy by using citric acid, diethylenetriamine, and cobalt(II) chloride hexahydrate as precursors. N,Co-CDs exhibited good ferromagnetic property and excellent optical properties even in extremely harsh environmental conditions, implying the huge potential applications of such N,Co-CDs in biological areas. On the basis of the IFE process between N,Co-CDs and DAP, N,Co-CDs were applied to establish ratiometric fluorescent probes for the indirect detection of cholesterol and uric acid that participated in enzyme-catalyzed H2O2-generation reactions. The established IFEbased fluorescent probes exhibited relatively low detection limits of 3.6 nM for cholesterol and 3.4 nM for uric acid, respectively. The fluorescent probe was successfully utilized for the determination of cholesterol and uric acid in human blood serum with satisfying results, which provided an informed perspective on the applications of such doped CDs to explore the specific and sensitive nanoprobe in disease diagnoses and clinical therapy
Direct Determination of Electron-Phonon Coupling Matrix Element in a Correlated System
High-resolution electron energy loss spectroscopy measurements have been
carried out on an optimally doped cuprate Bi2Sr2CaCu2O8+{\delta}. The
momentum-dependent linewidth and the dispersion of an A1 optical phonon are
obtained. Based on these data as well as the detailed knowledge of the
electronic structure from angle-resolved photoemission spectroscopy, we develop
a scheme to determine the full structure of electron-phonon coupling for a
specific phonon mode, thus providing a general method for directly resolving
the EPC matrix element in systems with anisotropic electronic structures
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