People entering the U.S. first need to get a visa. A visa allows the visa holder to travel to a port of entry in the United States and request the immigration officials permission to enter the country. The visa could be a non-immigrant visa if the person intends to stay in the U.S. temporarily.
Tobacco mosaic virus (TMV) is a positive-sense single stranded RNA virus that infects a wide range of plants, especially tobacco and other members of the family Solanaceae.The infection causes characteristic patterns, such as  mosaic -like mottling and discoloration on the leaves (hence the name).TMV was the first virus ever to be discovered.Although it was known from the late 19th century that an infectious disease was damaging tobacco crops, it was not until 1930 that the infectious agent was determined to be a virus.lthough it was known from the late 19th century that an infectious disease was damaging tobacco crops, it was not until 1930 that the infectious agent was determined to be a virus.
Web. 12 Sept. 2014. This article is about the different types of influenza viruses including H1N1. H1N1 is a type a virus and first appeared in April 2010 and it quickly became a global pandemic. It also says that in August of 2010 it was declared that H1N1 was no longer a global pandemic.This article was created on October 30, 2013.his article is about H1N1 and how it was first detected in the U.S. in April 2009 and also how the virus got its nickname, âswine fluâ. H1N1 got the nickname because tested showed that many of the genes in H1N1 was similar to the genes in viruses normally found in pigs.