The Transatlantic Tunnel is proposed to use a submerged floating tunnel which uses the same techniques as that of a submarine. The same idea is also being proposed for cars to use in crossing the fjords in Norway. The tunnel would be held in place by using 100,000 large tethering cables. The tunnel would be built using 54,000 prefabricated sections. The sections would consist of a layer of steel surrounding a layer of foam surrounding another layer of steel. If ever built it would be the largest and most expensive construction project in history.
Compiled By: Edward Apurba Singha
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Edward Apurba Singha
Alarm over bird flu
The sun is setting on the horizon ,a flock of birds is on the way to there nest. It is a consoling reminder of the eternal rhythms of nature. But we are afraid! Are they carrying the influenza virus which might kill hundreds of people?
The tiny foe: Influenza viruses are negative stranded RNA virus belonging to the family Orthomyxoviridae. Influenza A and B viruses are thought to comprise a single genus while C virus will probably be placed in a separate genus. Influenza virus can be either filamentous or roughly spherical .These viruses contain an envelop that is derived from the host cell and modified by the insertion of virus-coded protein. All influenza virus-envelops contain virus coded Hemagglutinin(HA). Influenza A and B also posses Neuraminidase(NA) activity. Hemagglutinin is important in host specification and entry. Neuraminidase functions at the end of the viral life cycle. It facilitates the release of virus particles from the infected cell surface and prevent self aggregation. The influenza genome is divided into 8 separate segment as seen in the ENTREZ genome report for the influenza virus. Each segments encodes one or more viral protein allowing the HA and NA to be encoded on separate segments. Antigenic variation is a frequent event with influenza A ,less frequently with B and almost none with C.
The killer under different masks: Influenza virus can cause highly contagious respiratory diseases that hospitalized over 200,000 and kills an average of 30,000 people in USA each year. Epidemics with a regional scope occur 1 to 4 years and add 10000 to 15000 deaths to the yearly toll. Global pandemic occurs on the average of once a decade and can affect between 20% and 40% of the world's population in a single year. The pandemic of 1918-19 for example, affected 200 million people ,killing over 20 million world wide. Notable pandemic also occurred in 1957 and 1968. The type species of the genus A that causes influenza and other diseases in human and animals are most notorious. Antigenic variation occurs frequently between strains , allowing classification into subtypes and variants, depending on HA and NA. The most frequently mentioned influenza A subtypes are: H1N1,H2N2,H3N2,H3N8,H5N1,H5N2,H7N7 and H9N2. The subtype H5N1 is the current source of much attention and that is generating speculation of a possible pandemic.
Flu scare: Bird flu was thought only to infect birds until the first human casualties were seen in Hong Kong in 1997.Birds excrete the virus in their feces, which dry and become pulverized (grind to powder) and are then inhaled. Experts believe that incase of co-infection (human and bird virus) could exchange genes between each other. The most frightening thing is that migratory wild water birds are natural carrier of this virus .Bangladesh is on their major migratory route. Our farmers rear large number of domestic ducks. They may get infected by those migratory birds.
Notorious in nature: Humans have little immunity to H5N1.Infecting sign and symptoms include high fever, chest pain, cough, bloody noses & gums, diarrhea and some organ failure(heart & kidney dysfunction). Several patients suffered brain swelling and inflammation. Air sacs in the lungs may fill with fluid, preventing oxygen from entering the blood stream. Scientists are now worried because studying a case in Vietnam they found that the virus can affect all parts of the body not just the lung , brain, heart or kidney.
Ducks being the Trojan horse of bird flu: Wild waterfowl including ducks are natural host of influenza A virus. The most interesting thing is that, these viruses really caused disease in ducks until 2002, when some H5N1 strains become highly pathogenic to them. But now a days these H5N1 viruses are reverting to nonpathogenic in ducks. They just shed viruses for an extended time than ever before indicating that the ducks have become natural reservoir for these viruses.
Some do's and don'ts: Don't need to be panicked, as currently there is no pandemic . Safe distance should be kept from live animal markets and poultry farms. Hands should be washed frequently with soap or alcohol- based gel. Undercooked eggs and poultry should not be taken. Close contact with the people should be avoided who have symptoms of the infection. Protective mask can be used if necessary.
Departments of Microbiology ,Dhaka University
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