Clustering is an important task in mining evolving data streams. Beside the limited memory and one-pass constraints, the nature of evolving data streams implies the following requirements for stream clustering: no assumption on the number of clusters, discovery of clusters with arbitrary shape and ability to handle outliers. While a lot of clustering algorithms for data streams have been proposed, they offer no solution to the combination of these requirements. In this paper, we present DenStream, a new approach for discovering clusters in an evolving data stream. The "dense" micro-cluster (named core-micro-cluster) is introduced to summarize the clusters with arbitrary shape, while the potential core-micro-cluster and outlier micro-cluster structures are proposed to maintain and distinguish the potential clusters and outliers. A novel pruning strategy is designed based on these concepts, which guarantees the precision of the weights of the micro-clusters with limited memory. Our performance study over a number of real and synthetic data sets demonstrates the effectiveness and efficiency of our method.

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With more than 1,800,000 cases and 110,000 deaths globally, COVID-19 is one of worst infectious disease outbreaks in history. This paper provides a critical review of the available evidence regarding the lessons learned from the Chinese experience with COVID-19 prevention and management. The steps that have led to a near disappearance of new cases in China included rapid sequencing of the virus to establish testing kits, which allowed tracking of infected persons in and out of Wuhan. In addition, aggressive quarantine measures included the R ESUM EAvec plus de 1 800 000 cas et 110 000 d ecès dans le monde, la COVID-19 est l'une des pires eclosions de maladies infectieuses de l'histoire. Ce document pr esente un examen critique des constats disponibles concernant les leçons tir ees de l'exp erience chinoise en matière de pr evention et de gestion de la COVID-19. Les mesures qui ont conduit à la quasi-disparition des nouveaux cas en Chine comprenaient le s equençage rapide du virus pour etablir des trousses de tests, ce qui a permis de suivre les personnes infect ees à l'int erieur et à Since mid-December 2019, there has been a worldwide outbreak of coronavirus disease (COVID)e19, caused by SARS-CoV-2 (formerly 2019-nCoV or HCoV-19) and first detected in Wuhan, China. The incubation period is 1-14 days (mean 5-6 days) in most cases, but can be as long as 24 days. 1 The most commonly seen characteristics of COVID-19 are fever, cough, and abnormal chest computed tomography. 2,3 At present, the Chinese chrysanthemum bat is thought to be the origin of SARS-CoV-2, based on sequence homology of 96% between SARS-CoV-2 and Bat-CoV-RaTG13. 4,5 The pangolin has been proposed as an intermediate host, but this has not been confirmed. 6,7 Human-to-human transmission of SARS-CoV-2 occurs mainly via respiratory droplets, 1 direct contact, 1 asymptomatic transmission, 8,9 and intrafamilial transmission. 3 SARS-CoV-2 can affect any demographic, including senior citizens, children, and pregnant women. 3,10 According to the World Health Organisation (WHO),

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