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In what part of the eye are the rods and cones located？
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Why roses are red and violets are blue？
Did you ever wonder why you see the colors you do or if other animals see the same colors that you see？ We see light that bounces off of things around us. When the light enters our eyes, special cells tell our brains about the light. These cells are called photoreceptors. Light is made of little bits called photons. When the sun shines, trillions and trillions of these little bits of light fall on the earth. The photons bounce off of almost everything and some of them enter our eyes. Those bits that enter our eyes allow us to sec. So, where does the color come from？
Starting in the 1600s with Sir Isaac Newton, scientists have believed that there are different kinds of photons. Different types give rise to our sense of colors. The different photons are said to have different wavelengths. Sunlight contains all the different wavelengths of photons. The visible wavelength colors can be seen when you look at a rainbow. Raindrops acting as natural prisms produce the colors.
How do our photoreceptors work？
We have two main types of photoreceptors called rods and cones. They are called rods and cones because of their shapes. These cells are located in a layer at the back of the eye called the retina. Rods are used to see in very dim light and only show the world to us in black and white. This is why you see only black and white when you are outside in the evening or in a dimly lit room. The other type of photoreceptors, the cones, allow us to see colors. They arc not as sensitive as the rods so they only work in bright light. There are three types of cones, one for each of the three main colors we see, red, green and blue.
Some people have a genetic defect that makes one or more of the cones fail. This condition is known as color deficiency. You may have heard it called color blindness. Color blindness is fairly common, affecting about nine percent of all humans. It is much more common in men than in women. To test for color blindness a special picture called an Ishihara test is used.
What about other animals？ What kind of colors do they see？ Most animals see fewer colors than we do, but some see more! We know this by looking at how many kinds of cone photoreceptors they have. Another good indication of what an animal can see is by looking at their own colors. The colors of their prey are also an indication of an animals ability to see color.
What three primary colors do we see？
For centuries, the death penalty was used in North America for murder, alleged witchcraft, and a few other crimes. Little thought was given to its justification; capital punishment was assumed to be morally and religiously justified. The first critical challenge to this practice came in 1821 when a study of the Louisiana criminal code recommended repeal of the death penalty. This suggestion was not adopted in Louisiana, but, ironically, it led to abolition of capital punishment in several South American countries.
In 1834, Pennsylvania became the first American state to end its use of executions. Although certain states followed Pennsylvania's lead, the history of the death penalty in the United States over the last 100 years has been rather uneven. As some states abolish capital punishment, others reinstate it. Currently, 37 states, the military, and federal statutes provide for execution for selected crimes.
The debate over the death penalty has traditionally focused on its appropriateness as a form. of punishment and its value in deterring criminals. Viewed from the functionalist perspective of Emile Durkheim, sanctioning of deviant acts helps to reinforce the standards of proper behavior. within a society. In this light, supporters of capital punishment insist that fear of execution will prevent at least some criminals from committing serious offenses. Moreover, in their view, the death penalty is justified even if it does not serve as a deterrent, because such criminals deserve to die for their crimes.
By contrast, opponents of capital punishment have long attacked it as "legalized murder". For example, in the last weeks of his term as governor of New Mexico in 1986, Toney Anaya commuted the death sentences of all five men awaiting execution in the state. Anaya called the death penalty "inhumane, immoral, and anti-God" and added that "my personal beliefs do not allow me to permit the execution of an individual in the name of the state."
Opponents of the death penalty point out that a 1985 report identified 343 Americans wrongly convicted of offenses punishable by death since 1900, 25 of whom were actually executed. For example, in 1979 a black man was sentenced to death for the murder of a 4-year-old white girl. He received a stay only days before his scheduled execution when the victim's mother implicated another person; the man's conviction was subsequently overturned. Critics argue that the possibility of error in the criminal justice system in itself makes capital punishment morally offensive. They also insist that the death penalty violates the Eighth Amendment's prohibition against "cruel and unusual punishment." Thus far, they have failed to persuade the Supreme Court that their constitutional argument is valid.
In 1976, in the case of Gregg vs. Georgia, the Court held that executions can be appropriate so long as they do not involve needless pain or suffering and are not grossly out of proportion to the severity of the crime. This ruling and others were especially significant, since no executions had taken place since 1967. In part, this reflected a lull in the criminal justice system as officials waited to see how the Supreme Court would assess the constitutionality of the death penalty. In the aftermath of the Court's decisions, one execution took place amidst national publicity in 1977 and another in 1979. Executions became more common in the early 1980s; in 1987, there were 25. Moreover, there were
The bizarre antics of sleepwalkers have puzzled police, perplexed scientists, and fascinated writers for centuries. There is an endless supply of stories about sleepwalkers. Persons have been said to climb on steep roofs, solve mathematical problems, compose music, walk through plate-glass windows, and commit murder in their sleep.
How many of these stories have a basis in fact, and how many are pure fakery？ No one knows, but if some of the most sensational stories should be taken with a barrel of salt, others are a matter of record.
In Revere, Massachusetts, a hundred policemen combed a waterfront neighborhood for a lost boy who left his home in his sleep and woke up five hours later on a strange sofa in a strange living room, with no idea how he had got there.
There is an early medical record of a somnambulist who wrote a novel in his sleep. And the great French writer Voltaire knew a sleepwalker who once got out of bed, dressed himself, made a polite bow, danced a minuet, and then undressed and went back to bed.
At the University of Iowa, a student was reported to have the habit of getting up in the middle of the night and walking three-quarters of a mile to the Iowa River. He would take a swim and then go back to his room to bed.
The world's champion sleepwalker was supposed to have been an Indian, Pandit Ramrakha, who walked sixteen miles along a dangerous road without realizing that he had left his bed. Second in line for the title is probably either a Vienna housewife or a British farmer. The woman did all her shopping on busy streets in her sleep. The farmer, in his sleep, visited a veterinarian miles away.
The leading expert on sleep in America claims that he has never seen a sleepwalker. He is Dr. Nathaniel Kleitman, a physiologist at the University of Chicago. He is said to know more about sleep than any other living man, and during the last thirty-five years has lost a lot of sleep watching people sleep. Says he, "Of course, I know that there are sleepwalkers because I have read about them in the newspapers. But none of my sleepers ever walked, and if I were to advertise for sleepwalkers for an experiment, I doubt that I'd get many takers."
Sleepwalking, nevertheless, is a scientific reality. Like hypnosis, it is one of those dramatic, eerie, awe-inspiring phenomena that sometimes border on the fantastic. It lends itself to controversy and misconceptions. What is certain about sleepwalking is that it is a symptom of emotional disturbance, and that the only way to cure it is to remove the worries and anxieties that cause it. Doctors say that somnambulism is much more common than is generally supposed. Some have estimated that there are four million somnambulists in the United States. Others set the figure even higher. Many sleepwalkers do not seek help and so are never put on record, which means that an accurate count can never be made.
The simplest explanation of sleepwalking is that it is the acting out of a vivid dream. The dream usually comes from guilt, worry, nervousness, or some other emotional conflict. The classic sleepwalker is Shakespeare's Lady Macbeth. Her nightly wanderings were caused by her guilty conscience at having committed murder. Shakespeare said of her, "The eyes are open but their sense is shut. "
The age-old question is: ls the sleepwalker actually awake or asleep？ Scientists have decided that he is about half-and-half. Like Lady Macbeth, he has weighty problems on his mind. Dr. Zeida Teplitz, who made a ten-year study of the subject, says, "Some people stay awake all night worrying about their problems. The sleepwalker thrashes them out in his sleep. He is awake in the muscular area, partially asleep in the sensory area." In other words, a person can walk in his sleep, move around, and do other things, but he does not think about what he is doing.
There are many myths
Web Du Bois was born a free man in his small village of Great Barington, Massachusetts, three years after the Civil War. For generations, the Du Bois family had been an accepted part of the community since before his great-grandfather had fought in the American Revolution.
Early on, Du Bois was given an awareness of his African-heritage, through the ancient songs his grandmother taught him. This awareness set him apart from his New England community, with an ancestry shrouded in mystery, in sharp contrast to the precisely accounted history of the Western world. This difference would be the foundation for his desire to change the way African-Americans co-existed in America.
As a student, Du Bois was considered something of a prodigy who excelled beyond the capabilities of his white peers. He found work as a correspondent for New York newspapers, and slowly began to realize the inhibitions of social boundaries he was expected to observe every step of the way. When racism tried to take his pride and dignity, he became more determined to make sure society recognized his achievements.
Clearly, Du Bois showed great promise, and although he dreamt of attending Harvard, some influential members of his community arranged for his education at Fisk University in Nashville. His experiences at Fisk changed his life; and he discovered his fate as a leader of the black struggle to free his people from oppression. At Fisk, Du Bois became acquainted with many sons and daughters of former slaves, who felt the pain of oppression and shared his sense of cultural and spiritual tradition. In the South, he saw his people being driven to a status of little difference from slavery, and saw them terrorized at the polls. He taught school during the summers in the eastern portion of Tennessee, and saw the suffering firsthand. He then resolved to dedicate his life to fighting the terrible racial oppression that held the black people down, both economically and politically.
Du Bois's determination was rewarded with a scholarship to Harvard, where he began the first scientific sociological studies in the United States. He felt that through science, he could dispel the irrational prejudices and ignorance that prevented racial equality. He went on to create great advancements in the study of race relations, but oppression continued with segregation laws, lynching, and terror tactics on the rise. Du Bois then formed the Niagara Movement, and in 1909, was a vital part in establishing the National Association for the Advancement of Colored People. He was also the editor of the NAACP magazine The Crisis from 1910 to 1934. In this stage of his life, he encouraged direct assaults on the legal, political, and economic system, which he felt blossomed out of the exploitation of the poor and powerless black community.
He became the most important black protest leader of the first half of the 20th century. His views clashed with Booker T. Washington, who felt that the black people of America had to simply accept discrimination, and hope to eventually earn respect and equality through hard work and success. Du Bois wrote The Souls of Black Folk in 1903, criticizing Booker, claiming that his ideas would lead to a perpetuation of oppression instead of freeing the black people from it. Du Bois's criticism lead to a branching out of the black civil rights movement, Booker's conservative followers, and a radical following of his critics.
Du Bois had established the Black Nationalism that was the inspiration for all black empowerment throughout the civil rights movement, but had begun during the progressive era. Although the movement that germinated from his ideas may have taken on a more violent form, Web Du Bois felt strongly that every human being could shape their own destinies with determination and hard work. Fie inspired hope by declaring that progress would come with the success of the small struggles for a be
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