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    Are you reading this page on a computer plugged into an electrical socket? If you are, that electricity is probably coming from burning coal or natural gas. Once upon a time, that would have been the end of the story. Today, electricity generation is buffeted by numerous factors: access to fossil fuels, peak oil, nuclear security and proliferation, pollution, and climate change. So depending on where you live, nuclear fission and high-pressure dammed-up water might be contributing to your local energy mix as well. Solar and wind power still play a comparatively small role, but because they’re basically inexhaustible and release no carbon pollution, intensive research is aiming to harvest them more efficiently and inexpensively. An even better long term solution might be to construct some mini-Suns right here on Earth—that’s effectively the goal of nuclear fusion research, though practical implementation is still a ways off. Maybe you’re reading on a ...
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Why is the color of the clear sky is blue? The molecules of air and other fine particles in the atmosphere have smaller size than the wavelength of visible light. These are more effective in scattering light of shorter wavelengths at the blue end than light of longer wavelengths at the red end. The red light has a wavelength about 1.8 times greater than blue light. Thus, when sunlight passes through the atmosphere, the fine particles in air scatter the blue color (shorter wavelengths) more strongly than red. The scattered blue light enters our eyes.That is why the color of the clear sky looks as blue.            
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Nearsightedness: Myopia causes, symptoms and correction By All About Vision Myopia (also called nearsightedness) is the most common cause of impaired vision in people under age 40. In recent years, its prevalence is growing at an alarming rate. Globally, research suggests that in the year 2000, roughly 25 percent of the world's population was nearsighted but by the year 2050, it's expected that roughly half the people on the planet will be myopic. Myopia symptoms If you are nearsighted, you will have difficulty reading road signs and seeing distant objects clearly, but will be able to see well for close-up tasks such as reading and computer use. Other signs and symptoms of myopia include squinting, eye strain and headaches   . Feeling fatigued when driving or playing sports also can be a symptom of uncorrected nearsightedness. If you experience these signs or symptoms while wearing your glasses or contact lenses,  schedule an eye exam  to see if yo...
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