H1N1 virus

Influenza A (H1N1) virus is a subtype of influenzavirus A and the most common cause of influenza (flu) in humans. Some strains of H1N1 are endemic in humans and cause a small fraction of all influenza-like illness and a large fraction of all seasonal influenza. H1N1 strains caused roughly half of all human flu infections in 2006.^[1] Other strains of H1N1 are endemic in pigs (swine influenza) and in birds (avian influenza).

In June 2009, World Health Organization declared that flu due to a new strain of swine-origin H1N1 was responsible for the 2009 flu pandemic. This strain is often called "swine flu" by the public media.

Influenza A virus strains are categorized according to two proteins found on the surface of the virus: hemagglutinin (H) and neuraminidase (N). All influenza A viruses contain hemagglutinin and neuraminidase, but the structures of these proteins differ from strain to strain, due to rapid genetic mutation in the viral genome.

Influenza A virus strains are assigned an H number and an N number based on which forms of these two proteins the strain contains. There are 16 H and 9 N subtypes known in birds, but only H 1, 2 and 3, and N 1 and 2 are commonly found in humans.^[3]

In the 2009 flu pandemic, the virus isolated from patients in the United States was found to be made up of genetic elements from four different flu viruses – North American swine influenza, North American avian influenza, human influenza, and swine influenza virus typically found in Asia and Europe – "an unusually mongrelised mix of genetic sequences."^[13] This new strain appears to be a result of reassortment of human influenza and swine influenza viruses, in all four different strains of subtype H1N1.

Preliminary genetic characterization found that the hemagglutinin (HA) gene was similar to that of swine flu viruses present in U.S. pigs since 1999, but the neuraminidase (NA) and matrix protein (M) genes resembled versions present in European swine flu isolates. The six genes from American swine flu are themselves mixtures of swine flu, bird flu, and human flu viruses.^[14] While viruses with this genetic makeup had not previously been found to be circulating in humans or pigs, there is no formal national surveillance system to determine what viruses are circulating in pigs in the U.S.^[15]

On June 11, 2009, the WHO declared an H1N1 pandemic, moving the alert level to phase 6, marking the first global pandemic since the 1968 Hong Kong flu.^[16]

LoVe

Love is any of a number of emotions and experiences related to a sense of strong affection^[1] and attachment. The word love can refer to a variety of different feelings, states, and attitudes, ranging from generic pleasure ("I loved that meal") to intense interpersonal attraction ("I love my boyfriend"). This diversity of uses and meanings, combined with the complexity of the feelings involved, makes love unusually difficult to consistently define, even compared to other emotional states.

As an abstract concept, love usually refers to a deep, ineffable feeling of tenderly caring for another person. Even this limited conception of love, however, encompasses a wealth of different feelings, from the passionate desire and intimacy of romantic love to the nonsexual emotional closeness of familial and platonic love^[2] to the profound oneness or devotion of religious love.^[3] Love in its various forms acts as a major facilitator of interpersonal relationships and, owing to its central psychological importance, is one of the most common themes in the creative arts.

The English word "love" can have a variety of related but distinct meanings in different contexts. Often, other languages use multiple words to express some of the different concepts that English relies mainly on "love" to encapsulate; one example is the plurality of Greek words for "love." Cultural differences in conceptualizing love thus make it doubly difficult to establish any universal definition.^[4]

Although the nature or essence of love is a subject of frequent debate, different aspects of the word can be clarified by determining what isn't love. As a general expression of positive sentiment (a stronger form of like), love is commonly contrasted with hate (or neutral apathy); as a less sexual and more emotionally intimate form of romantic attachment, love is commonly contrasted with lust; and as an interpersonal relationship with romantic overtones, love is commonly contrasted with friendship, although other definitions of the word love may be applied to close friendships in certain contexts.

There are two types of love,impersonal love.A person can be said to love a country, principle, or goal if they value it greatly and are deeply committed to it. Similarly, compassionate outreach and volunteer workers' "love" of their cause may sometimes be borne not of interpersonal love, but impersonal love coupled with altruism and strong political convictions. People can also "love" material objects, animals, or activities if they invest themselves in bonding or otherwise identifying with those things. If sexual passion is also involved, this condition is called paraphilia.^[7]

Interpersonal love refers to love between human beings. It is a more potent sentiment than a simple liking for another. Unrequited love refers to those feelings of love that are not reciprocated. Interpersonal love is most closely associated with interpersonal relationships. Such love might exist between family members, friends, and couples. There are also a number of psychological disorders related to love, such as erotomania.

Throughout history, philosophy and religion have done the most speculation on the phenomenon of love. In the last century, the science of psychology has written a great deal on the subject. In recent years, the sciences of evolutionary psychology, evolutionary biology, anthropology, neuroscience, and biology have added to the understanding of the nature and function of love.