Friday, October 28, 2011
Butterfly background Images
Artistic depictions of butterflies have been used in many cultures including Egyptian hieroglyphs 3500 years ago.
Host plants often have toxic substances in them and caterpillars are able to sequester these substances and retain them into the adult stage. This helps making them unpalatable to birds and other predators. Such unpalatibility is advertised using bright red, orange, black or white warning colours. The toxic chemicals in plants are often evolved specifically to prevent them from being eaten by insects. Insects in turn develop countermeasures or make use of these toxins for their own survival. This "arms race" has led to the coevolution of insects and their host plants.
Many of the tropical butterflies have distinctive seasonal forms. This phenomenon is termed seasonal polyphenism and the seasonal forms of the butterflies are called the dry-season and wet-season forms. How the season affects the genetic expression of patterns is still a subject of research. Experimental modification by ecdysone hormone treatment has demonstrated that it is possible to control the continuum of expression of variation between the wet and dry-season forms. The dry-season forms are usually more cryptic and it has been suggested that the protection offered may be an adaptation. Some also show greater dark colours in the wet-season form which may have thermoregulatory advantages by increasing ability to absorb solar radiation.
The idiom "butterflies in the stomach" is used to describe a state of nervousness.
Butterflies are characterized by their scale-covered wings. The coloration of butterfly wings is created by minute scales. These scales are pigmented with melanins that give them blacks and browns, but blues, greens, reds and iridescence are usually created not by pigments but the microstructure of the scales. This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales. The scales cling somewhat loosely to the wing and come off easily without harming the butterfly.
Host plants often have toxic substances in them and caterpillars are able to sequester these substances and retain them into the adult stage. This helps making them unpalatable to birds and other predators. Such unpalatibility is advertised using bright red, orange, black or white warning colours. The toxic chemicals in plants are often evolved specifically to prevent them from being eaten by insects. Insects in turn develop countermeasures or make use of these toxins for their own survival. This "arms race" has led to the coevolution of insects and their host plants.
Many of the tropical butterflies have distinctive seasonal forms. This phenomenon is termed seasonal polyphenism and the seasonal forms of the butterflies are called the dry-season and wet-season forms. How the season affects the genetic expression of patterns is still a subject of research. Experimental modification by ecdysone hormone treatment has demonstrated that it is possible to control the continuum of expression of variation between the wet and dry-season forms. The dry-season forms are usually more cryptic and it has been suggested that the protection offered may be an adaptation. Some also show greater dark colours in the wet-season form which may have thermoregulatory advantages by increasing ability to absorb solar radiation.
The idiom "butterflies in the stomach" is used to describe a state of nervousness.
Butterflies are characterized by their scale-covered wings. The coloration of butterfly wings is created by minute scales. These scales are pigmented with melanins that give them blacks and browns, but blues, greens, reds and iridescence are usually created not by pigments but the microstructure of the scales. This structural coloration is the result of coherent scattering of light by the photonic crystal nature of the scales. The scales cling somewhat loosely to the wing and come off easily without harming the butterfly.
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Seriation · Stratification · Fluorine absorption dating
Chronicle · New Chronology · Periodization · Synchronoptic view · Timeline · Year zero · Circa · Floruit · ASPRO chronology
There are only 14 different calendars when Easter Sunday is not involved. Each calendar is determined by the day of the week January 1 falls on and whether or not the year is a leap year. However, when Easter Sunday is included, there are 70 different calendars (two for each date of Easter).
Fiscal calendars are also used by businesses. This is where the fiscal year is just any set of 12 months. This set of 12 months can start and end at any point on the Gregorian calendar. This is the most common usage of fiscal calendars.
Seriation · Stratification · Fluorine absorption dating
Chronicle · New Chronology · Periodization · Synchronoptic view · Timeline · Year zero · Circa · Floruit · ASPRO chronology
There are only 14 different calendars when Easter Sunday is not involved. Each calendar is determined by the day of the week January 1 falls on and whether or not the year is a leap year. However, when Easter Sunday is included, there are 70 different calendars (two for each date of Easter).
Fiscal calendars are also used by businesses. This is where the fiscal year is just any set of 12 months. This set of 12 months can start and end at any point on the Gregorian calendar. This is the most common usage of fiscal calendars.
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The Airports Authority's actions ignited a public preservation effort that culminated in 1992 with legislation that the Virginia General Assembly enacted and that Governor L. Douglas Wilder approved. The legislation required the Airports Authority to "take all steps necessary to insure the preservation in place, the study, and the interpretation to the public" of the Abingdon ruins during a one year period that followed the law's enactment. During that period, James Wilding, the general manager of the Airports Authority, reported to the Authority's planning committee that multiple options had been identified that would provide adequate parking without having to excavate the Abingdon site.
In 1864, the Federal government of the United States confiscated Abingdon and the nearby "Arlington Plantation" after the owners of each property failed to pay their taxes in person. (A tenant had offered to pay Abingdon's taxes on behalf of the property owner (Bushrod Hunter). However, the government's tax collector refused to accept the payment.) The government then sold the Abingdon property to Lucius E. Chittenden, Register of the Treasury in the Abraham Lincoln administration. Chittenden then leased the property to Henry M. Bennett.
Two years later, in 1989, the Airports Authority revealed that it was planning to replace the Abingdon ruins with a new parking garage. To comply with the provisions of Section 106 of the National Historic Preservation Act of 1966, the Authority commissioned a series of studies that described the history of Abingdon and the archaeological features of the Abingdon site and its surroundings. The final report of the series, issued in 1991, summarized the studies and examined several alternative treatments of the site. The report stated:
According to one account, John Parke Custis served on George Washington's staff during the Siege of Boston in 1775-1776 and became an emissary to the British forces there. He befriended a young British officer on the staff of General William Howe, 5th Viscount Howe. While in Cambridge, Massachusetts, the officer gave Custis a weeping willow (Salix babylonica) twig that the officer had taken from a famous tree that Alexander Pope had planted at Twickenham and that was first of its kind in England. The officer had intended to plant his willow sprig wrapped in oiled silk along a stream on land he would seize from the Americans. However, following his army's defeat, he decided to give the sprig to Custis. Custis then planted the twig at Abingdon. The resulting tree reportedly became the parent of all of the weeping willows in the United States at the time of the account (1881).
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