CSPM: A Contrastive Spatiotemporal Preference Model for CTR Prediction in On-Demand Food Delivery Services

Click-through rate (CTR) prediction is a crucial task in the context of an online on-demand food delivery (OFD) platform for precisely estimating the probability of a user clicking on food items. Unlike universal e-commerce platforms such as Taobao and Amazon, user behaviors and interests on the OFD platform are more location and time-sensitive due to limited delivery ranges and regional commodity supplies. However, existing CTR prediction algorithms in OFD scenarios concentrate on capturing interest from historical behavior sequences, which fails to effectively model the complex spatiotemporal information within features, leading to poor performance. To address this challenge, this paper introduces the Contrastive Sres under different search states using three modules: contrastive spatiotemporal representation learning (CSRL), spatiotemporal preference extractor (StPE), and spatiotemporal information filter (StIF). CSRL utilizes a contrastive learning framework to generate a spatiotemporal activation representation (SAR) for the search action. StPE employs SAR to activate users' diverse preferences related to location and time from the historical behavior sequence field, using a multi-head attention mechanism. StIF incorporates SAR into a gating network to automatically capture important features with latent spatiotemporal effects. Extensive experiments conducted on two large-scale industrial datasets demonstrate the state-of-the-art performance of CSPM. Notably, CSPM has been successfully deployed in Alibaba's online OFD platform Ele.me, resulting in a significant 0.88% lift in CTR, which has substantial business implications

Automatic Construction of Semantic Dictionary for Question Categorization

An automatic method for building a semantic dictionary from existing questions in a pattern-based question answering system is proposed for question categorization. This dictionary consists of two main parts: Semantic Domain Terms (SDT), which is a domain specific term list, and Semantic Labeled Terms (SLT), which contain common terms tagged with semantic labels. The semantic dictionary is built using the proposed method on a set of 2509 questions with semantic patterns in our system. 3390 questions without semantic patterns are used as ground truth to test its performance. Experimental results show that the precision of question classification is improved by 7.5% in average after using the constructed semantic dictionary compared with the baseline method

Associations between Phase Angle Values Obtained by Bioelectrical Impedance Analysis and Nonalcoholic Fatty Liver Disease in an Overweight Population

Objective. There is a limited diagnosis of nonalcoholic fatty liver disease (NAFLD). Thus, the noninvasive assessments are worth exploring. We determined the associations of phase angles (PhAs) obtained from bioelectric impedance analysis (BIA) with the risk of NAFLD in an overweight population. Methods. A study involving 953 overweight participants was conducted in Wuhan city, China. The associations between PhAs (right arm, left arm, body trunk, right leg, left leg, and whole body) and the risk of NAFLD were conducted using multivariate logistic regression analyses. The associations of PhAs with the controlled attenuation parameter (CAP), a noninvasive assessment of liver steatosis and fibrosis, were also evaluated by both linear and logistic regression analyses. Results. The PhA values of the whole body, trunk, and legs were significantly lower (P<0.05) in the NAFLD group than the non-NAFLD group. After adjustment for BMI, gender, education, income/year, hyperlipidemia, hypertension, diabetes, smoking, passive smoking, and drinking, significant associations of PhA values of the right leg, left leg, and whole body with the risk of NAFLD were observed. In addition, the PhA of the right leg, left leg, and whole body were significantly related to the CAP values. Further stratified analyses indicated that these associations were significant in the participants with BMI <30, but not in the participants with BMI ≥30. Conclusions. PhAs might be effective indicators in the management of NAFLD among overweight people

β‑Furan-Fused bis(Difluoroboron)-1,2-bis((1H-pyrrol-2-yl)methylene)hydrazine Fluorescent Dyes in the Visible Deep-Red Region

Novel β-furan-fused bis­(difluoroboron)-1,2-bis­((1H-pyrrol-2-yl)­methylene)­hydrazine (BOPHY) fluorescent dyes (<b>F-BOPHY1</b>–<b>3</b>) were prepared through an efficient process, and their structures were confirmed by ¹H NMR spectroscopy, ¹³C NMR spectroscopy, MALDI-TOF HRMS, and element analysis. Their optical properties were then characterized by UV–vis absorption and photoluminescence (PL) spectroscopy. The UV–vis absorption and PL spectra of the dyes shifted to longer wavelengths relative to those of BOPHY because of the fusion of their furan rings, which extended π-conjugation of the molecules. All of the dyes exhibited large extinction coefficients (109700–12300 M^–1 cm^–1), deep-red fluorescence emission (646–667 nm), moderate fluorescence quantum yields (0.30–0.45), as well as high chemical stability and photostability in solution. These advantageous properties show that these compounds are important to the design of efficient long-wavelength fluorescent dyes and are suitable for various applications in biotechnology and materials science