Arbovirus is a shortened name given to viruses that are transmitted by arthropods, or arthropod-borne viruses .
Some Arboviruses are able to cause emergent disease. Arthropods are able to transmit the virus upon biting allowing the virus to enter the bloodstream which can cause viraemia.
The majority of the Arboviruses are spherical in shape although a few are rod shaped. They are 17-150 nm in diameter and most have an RNA genome (the single exception is African Swine Fever virus, which has a DNA genome). These viruses do not normally infect humans but if they do, they usually cause a mild infection such as a fever or a rash. Others however are epidemic and can cause serious infections such as meningitis and encephalitis that can be fatal.
There are ways of preventing these infections from occurring such as using mosquito repellents and getting rid of the breeding grounds that mosquitoes use. Insecticides can also be used. People can also reduce the risk of getting bitten by the mosquito by wearing protective clothing.
The immune system plays a role in defense against the infections. Arboviruses usually stimulate interferon. Antibodies are made and these can prevent viraemia from occurring. The cell mediated immunity is also important.
Arbovirus infections can be diagnosed by carrying out ELISA and PCR techniques. Complement fixation can also be used.
Tuesday, March 31, 2009
Visual pollution
Visual pollution is the term given to unattractive or unnatural (human-made) visual elements of a vista, a landscape, or any other thing that a person might not want to look at. Visual pollution is an aesthetic issue, referring to the impacts of pollution that impair one's ability to enjoy a vista or view. The term is used broadly to cover visibility, limits on the ability to view distant objects, as well as the more subjective issue of visual clutter, structures that intrude upon otherwise "pretty" scenes. Commonly cited examples are advertisements, billboards, landfills, houses, automobiles, traffic signs, roadsigns, highways, roadways, litter, graffiti, overhead powerlines, utility poles, contrails, skywriting, buildings and weeds.
Quicksand
Quicksand is a colloid hydrogel consisting of fine granular matter (such as sand or silt), clay, and salt water. In the name, as in that of quicksilver (mercury), "quick" does not mean "fast," but "living" (cf. the expression the quick and the dead).
Water circulation underground can focus in an area with just the right mixture of fine sands and other materials such as clay. The water moves up and then down slowly in a convection-like manner throughout a column of sand under optimal conditions, and the sand remains a generally solid mass. This lubricates the sand particles and renders them unable to support any significant weight, since they move around with very little friction, behaving more like a liquid when exposed to stress. Since the water does not usually go all the way up through the sand, the sand above does not appear to move at all, and can support leaves and other small debris, making quicksand difficult to distinguish from the surrounding environment.
Properties
Quicksand is a non-Newtonian fluid: when undisturbed it often appears to be solid ("gel" form), but a minor (less than 1%) change in the stress on the quicksand will cause a sudden decrease in its viscosity ("sol" form). After an initial disturbance—such as a person attempting to walk on it—the water and sand in the quicksand separate and dense regions of sand sediment form; it is because of the formation of these high volume fraction regions that the viscosity of the quicksand seems to increase suddenly. Someone stepping in it will start to sink. In order to move within the quicksand, a person or object must apply sufficient pressure on the compacted sand to re-introduce enough water to liquefy it. The forces required to do this are quite large: to remove a foot from quicksand at a speed of one centimeter per second would require the same amount of force as "that needed to lift a medium-sized car."
Recent research findings
It was commonly believed that the behavior of quicksand was due solely to saturated or supersaturated suspensions of granules in water. Pressure from underground sources of water would separate and suspend the granular particles, reducing the friction between them. As of September 2005, it has been shown that it is the presence of salt that is largely responsible The stability of the colloidal quicksand is compromised by the presence of salt, increasing the likelihood of sand flocculation and the formation of the high viscosity regions of sediment responsible for quicksand's "trapping" power.
Prevalence
Quicksand may be found inland (on riverbanks, near lakes, or in marshes), or near the coast.
One region notorious for its quicksands is Morecambe Bay, England. As the bay is very broad and shallow, a person trapped by the quicksand would be exposed to the danger of the returning tide, which can come in rapidly.
Water circulation underground can focus in an area with just the right mixture of fine sands and other materials such as clay. The water moves up and then down slowly in a convection-like manner throughout a column of sand under optimal conditions, and the sand remains a generally solid mass. This lubricates the sand particles and renders them unable to support any significant weight, since they move around with very little friction, behaving more like a liquid when exposed to stress. Since the water does not usually go all the way up through the sand, the sand above does not appear to move at all, and can support leaves and other small debris, making quicksand difficult to distinguish from the surrounding environment.
Properties
Quicksand is a non-Newtonian fluid: when undisturbed it often appears to be solid ("gel" form), but a minor (less than 1%) change in the stress on the quicksand will cause a sudden decrease in its viscosity ("sol" form). After an initial disturbance—such as a person attempting to walk on it—the water and sand in the quicksand separate and dense regions of sand sediment form; it is because of the formation of these high volume fraction regions that the viscosity of the quicksand seems to increase suddenly. Someone stepping in it will start to sink. In order to move within the quicksand, a person or object must apply sufficient pressure on the compacted sand to re-introduce enough water to liquefy it. The forces required to do this are quite large: to remove a foot from quicksand at a speed of one centimeter per second would require the same amount of force as "that needed to lift a medium-sized car."
Recent research findings
It was commonly believed that the behavior of quicksand was due solely to saturated or supersaturated suspensions of granules in water. Pressure from underground sources of water would separate and suspend the granular particles, reducing the friction between them. As of September 2005, it has been shown that it is the presence of salt that is largely responsible The stability of the colloidal quicksand is compromised by the presence of salt, increasing the likelihood of sand flocculation and the formation of the high viscosity regions of sediment responsible for quicksand's "trapping" power.
Prevalence
Quicksand may be found inland (on riverbanks, near lakes, or in marshes), or near the coast.
One region notorious for its quicksands is Morecambe Bay, England. As the bay is very broad and shallow, a person trapped by the quicksand would be exposed to the danger of the returning tide, which can come in rapidly.
Wednesday, February 25, 2009
Environmental adult education
Environmental Adult Education is recognized as a “hybrid outgrowth of the environmental movement and adult education, combining an ecological orientation with a learning paradigm to provide a vigorous educational approach to environmental concerns” (Sumner, 2003).
In laymen’s terms, environmental adult education refers to efforts in teaching environmental issues and how individuals and businesses can manage or change their lifestyles and ecosystems to live sustainably. The overarching goal of this field of study is to educate our global societies to live more sustainably.
From the classroom to the forests, fields, streams and prairies, environmental adult education takes place in both formal and nonformal learning environments and programs.
History
Environmental adult education is a relatively new and unique field of study and practice. It is a community-based method in which educators listen and respect the input of learners, and all participants are considered essential (Haugen, 2006).
During the last thirty years, environmental adult education has evolved. For more than a century, environmental and conservation organizations taught adults environmental education with very little structure.
The United States was one of the first countries to officially recognize environmental education. During a joint House-Senate session in 1968, Congress acknowledged the importance of environmental education, and in 1970 passed the Environmental Education Act, which established the Office of Environmental Education (American Geological Institute 2000).
Timeline of the Ideology of Environmental Adult Education (EAE):
* Mid-1970s: EAE recognized as distinct field of study
* Late 1980s: EAE focus on learner experience
* Late 1990s, Early 2000: Focus shifted to how to teach EAE
* 1997: United Nations Educational, Scientific, and Cultural Organization (UNESCO) hosted conference on adult education with EAE being one of the 33 workshops presented
In laymen’s terms, environmental adult education refers to efforts in teaching environmental issues and how individuals and businesses can manage or change their lifestyles and ecosystems to live sustainably. The overarching goal of this field of study is to educate our global societies to live more sustainably.
From the classroom to the forests, fields, streams and prairies, environmental adult education takes place in both formal and nonformal learning environments and programs.
History
Environmental adult education is a relatively new and unique field of study and practice. It is a community-based method in which educators listen and respect the input of learners, and all participants are considered essential (Haugen, 2006).
During the last thirty years, environmental adult education has evolved. For more than a century, environmental and conservation organizations taught adults environmental education with very little structure.
The United States was one of the first countries to officially recognize environmental education. During a joint House-Senate session in 1968, Congress acknowledged the importance of environmental education, and in 1970 passed the Environmental Education Act, which established the Office of Environmental Education (American Geological Institute 2000).
Timeline of the Ideology of Environmental Adult Education (EAE):
* Mid-1970s: EAE recognized as distinct field of study
* Late 1980s: EAE focus on learner experience
* Late 1990s, Early 2000: Focus shifted to how to teach EAE
* 1997: United Nations Educational, Scientific, and Cultural Organization (UNESCO) hosted conference on adult education with EAE being one of the 33 workshops presented
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