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During the COVID-19 pandemic, Glotzbach announced he was opening Quizlet's premium service, Quizlet Teacher, for free to all users who have an account registered as a teacher. [ 19 ] Quizlet made its first acquisition in March 2021, with the purchase of Slader, which offered detailed explanations of textbook concepts and practice problems, and ...
Cas9 (or "CRISPR-associated protein 9") is an enzyme that uses CRISPR sequences as a guide to recognize and open up specific strands of DNA that are complementary to the CRISPR sequence. Cas9 enzymes together with CRISPR sequences form the basis of a technology known as CRISPR-Cas9 that can be used to edit genes within living organisms.
The timeline of the COVID-19 pandemic lists the articles containing the chronology and epidemiology of SARS-CoV-2, [1] the virus that causes the coronavirus disease 2019 and is responsible for the COVID-19 pandemic. The first human cases of COVID-19 occurred in Wuhan, People's Republic of China, on or about 17 November 2019. [2]
The history of coronaviruses is an account of the discovery of the diseases caused by coronaviruses and the diseases they cause. It starts with the first report of a new type of upper-respiratory tract disease among chickens in North Dakota, U.S., in 1931.
[21] [22] According to the World Health Organization, approximately 10 million new TB infections occur every year, and 1.5 million people die from it each year – making it the world's top infectious killer (before COVID-19 pandemic). [21] However, there is a lack of sources which describe major TB epidemics with definite time spans and death ...
COVID-19 is the deadliest pandemic in US history; [360] it was the third-leading cause of death in the US in 2020, behind heart disease and cancer. [361] From 2019 to 2020, US life expectancy dropped by 3 years for Hispanic Americans, 2.9 years for African Americans, and 1.2 years for white Americans. [362]
The name "coronavirus" is derived from Latin corona, meaning "crown" or "wreath", itself a borrowing from Greek κορώνη korṓnē, "garland, wreath". [8] [9] The name was coined by June Almeida and David Tyrrell who first observed and studied human coronaviruses. [10]
Coronavirus diseases are caused by viruses in the coronavirus subfamily, a group of related RNA viruses that cause diseases in mammals and birds. In humans and birds, the group of viruses cause respiratory tract infections that can range from mild to lethal.