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Knowledge Graphs (KGs) such as Resource Description Framework (RDF) data represent relationships between various entities through the structure of triples ( $ < subject$ , $predicate$ , $object>$ ). Knowledge graph embedding (KGE) is crucial in machine learning applications, specifically in node classification and link prediction tasks. KGE remains a vital research topic within the semantic web community. RDF-star introduces the concept of a quoted triple (QT), a specific form of triple employed either as the subject or object within another triple. Moreover, RDF-star permits a QT to act as compositional entities within another QT, thereby enabling the representation of recursive, hyper-relational KGs with nested structures. However, existing KGE models fail to adequately learn the semantics of QTs and entities, primarily because they do not account for RDF-star graphs containing multi-leveled nested QTs and QT–QT relationships. This study introduces RDF-star2Vec, a novel KGE model specifically designed for RDF-star graphs. RDF-star2Vec introduces graph walk techniques that enable probabilistic transitions between a QT and its compositional entities. Feature vectors for QTs, entities, and relations are derived from generated sequences through the structured skip-gram model. Additionally, we provide a dataset and a benchmarking framework for data mining tasks focused on complex RDF-star graphs. Evaluative experiments demonstrated that RDF-star2Vec yielded superior performance compared to recent extensions of RDF2Vec in various tasks including classification, clustering, entity relatedness, and QT similarity.

Objective The association between the severity of COVID-19 and gastrointestinal (GI) bleeding is unknown. This study aimed to determine whether the severity of COVID-19 is a risk factor for GI bleeding.Design A multicentre, retrospective cohort study was conducted on hospitalised patients with COVID-19 between January 2020 and December 2021. The severity of COVID-19 was classified according to the National Institute of Health severity classification. The primary outcome was the occurrence of GI bleeding during hospitalisation. The main analysis compared the relationship between the severity of COVID-19 and the occurrence of GI bleeding. Multivariable logistic regression analysis was performed to evaluate the association between the severity of COVID-19 and the occurrence of GI bleeding.Results 12 044 patients were included. 4165 (34.6%) and 1257 (10.4%) patients had severe and critical COVID-19, respectively, and 55 (0.5%) experienced GI bleeding. Multivariable analysis showed that patients with severe COVID-19 had a significantly higher risk of GI bleeding than patients with non-severe COVID-19 (OR: 3.013, 95% CI: 1.222 to 7.427). Patients with critical COVID-19 also had a significantly higher risk of GI bleeding (OR: 15.632, 95% CI: 6.581 to 37.130). Patients with severe COVID-19 had a significantly increased risk of lower GI bleeding (OR: 10.349, 95% CI: 1.253 to 85.463), but the risk of upper GI bleeding was unchanged (OR: 1.875, 95% CI: 0.658 to 5.342).Conclusion The severity of COVID-19 is associated with GI bleeding, and especially lower GI bleeding was associated with the severity of COVID-19. Patients with severe or critical COVID-19 should be treated with caution as they are at higher risk for GI bleeding.

The three-dimensional ordering of the gallium (Ga) adlayers on GaN(0001) and (000 $\bar{1}$ ) surfaces was probed using in situ X-ray scattering under MBE conditions. An ordered bilayer of Ga forms on GaN(0001) but the ordering decreases at substrate temperatures of

Crohn's disease is a rare cause of appendicitis. In this report, we describe a case of Crohn's disease that was diagnosed 4 months after surgery for acute appendicitis in a 15-year-old boy. He was followed carefully after surgery, because the pathological findings showed the presence of a granuloma, which may imply Crohn's disease. At four months after surgery, he visited our hospital with a chief complaint of diarrhea. Lower gastrointestinal endoscopy revealed longitudinal ulcerative lesions in the entire colon. Taken together with the pathological findings of the appendix, the patient was diagnosed with Crohn's disease. The patient is currently on a continuous infliximab regimen.In the present case, although there were no symptoms at the time of surgery, we informed the patient and his parents of the pathology results in advance, and told them to return to our clinic as soon as symptoms appeared. The pathological diagnosis led to an early diagnosis of CD. Although rare, Crohn's disease should be kept in mind as a cause of appendicitis.