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04.08.2016
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Navigation lights: All aircraft are equipped with a steady light near the leading edge of each wingtip. Anti-Collision Beacon lights: Two beacon lights are fitted to aircraft near the center of the fuselage. Strobe lights: High-intensity strobe lights that flash a white-colored light are located on each wingtip. Taxi lights: A bright white lamp is located on the nose landing gear strut of most planes. Wheel Well lights: Some planes are equipped with additional lights in the nose and main gear wheel wells.
At low light levels, however, you could see to function easily, because the rods receptors use a chemical photopigments that function best in low light. Thus, to help an achromat see better in the light, we must turn the light level into the night so the rods can function.
Any dark filter will reduce the light reaching the retina and may help the achromats begin to see better. The low energy of red light has been used in darkrooms for decades to work with film without over exposing it. In a similar way, the achromat's red lenses block the higher energy blue  end of the spectrum, allowing primarily red light to pass through to the retina. Bright white light would quickly bleach out the rods receptors owing to the high energy of the shorter wavelength.
Magenta filters may be helpful in blue cone monochromatism and in some incomplete rod monochromats. To avoid that loss of the remaining blue channel, we must select a filter that allows some blue light to pass through to the retina.
Estimates say that light pollution is rising as much as 20 percent per year in some locations, with an average of 6 percent. Even the laptops and tablets that we use to read in the evening probably reduce melatonin secretions, since their displays are rich in blue light. One major aspect of night lighting that has changed with the surge in electric lighting is the role of clouds.
Left: clouds over Glacier National Park form dark patches against the brilliant starlit sky. Light at night is one of the great blessings of the electric age, making cities safer and nights more rewarding, enjoyable and profitable, and loosening the link between sundown and bedtime. Melatonin also can fight breast and prostate cancers, says Richard Stevens of the University of Connecticut. Night-shift work is notoriously hard on the body; largely because it de-programs the body clock. Although light inhibits the release of melatonin, the possible linkage was not taken seriously for years. Although light is a key to setting or upsetting the circadian rhythm, other factors, such as sleep and eating patterns, also play a role in our chronobiology. A 2005 study showed that blood taken from women exposed to light at night supported human breast tumors growing in mice.
Satellite photo before the Northeast blackout of 2003 United States plunged millions into darkness. A recently-recognized light-detecting cell in the retina alerts the brain to a wavelength of blue light that’s most intense in the morning. Research by Eve Van Cauter of the University of Chicago links circadian disruption and obesity.
Laptops and other digital thingies bring the world to your fingertips — but how do they affect organisms that evolved in a never-ending cycle of day and night?
Broadly speaking, the wide biological implications of light and time of day are more evidence that we have evolved in a world dominated, and calibrated, by the sun.
That list includes cyanobacteria, the single-celled organisms that oxygenated the planet and originated as much as three billion years ago. These devices, after all, are rich in the blue light that is so destabilizing to the body clock.


When wildlife scientists worry about the glare of light at night, they mostly think about street lights and sky glow — the gauzy cloud of brightness that envelops our cities.
Last week’s meeting of the Ecological Society of America provided more evidence for the ecological implications of light pollution.
Scientists in Israel exposed two mouse species, one nocturnal and one diurnal, to three hours of artificial light, starting at dusk.
The opossum, the only marsupial in North America, climbs trees and scavenges for food at night.
A European study showed that males in four of five bird species started singing earlier in the morning near street lights, and copulated twice as much with non-mates. Insects are major ecological players, and a 2006 study from Zurich, Switzerland, measured the impact of building lights on insects at an office building near a stream. In 2011, experimenters in the Netherlands erected 120 all-night lights at the edge of forests. This outdoor experiment shines white, green or this eerie red light, which is deficient in the short wavelengths that affect circadian rhythms. Filters on a commercial light-measurement device are conducive to widespread monitoring of light at night, filling in essential details about which wavelengths are present, and at what levels. Kyba says the last transformation of city light, following the adoption of mercury and sodium-vapor lights about 40 years ago, went undocumented. Because LEDs can be tuned to intensity, wavelength and direction, better data on effects can help cities and citizens choose lighting that meets legitimate needs without overwhelming animal and human retinas, Kyba says. LEDs can be positioned to illuminate streets and sidewalks without shining into bedroom windows or up to the sky.
As the ecological impacts of light pollution become clearer, the details will allow for improvements. BibliographyKyba CCM et al, (2011) Cloud Coverage Acts as an Amplifier for Ecological Light Pollution in Urban Ecosystems. It is amazingly brilliant, simple to operate, does what it says, makes no mistakes, and it serves a higher purpose. This is one of Motorola's latest Android smartphones and it has an interesting modular design that allows for custom back covers, snap on speakers and snap on projector. Rod monochromats may have complete colorblindness or be incomplete with traces of residual color vision, which may affect the color selection. Blue cone monochromats often use a magenta filter to allow some blue through to the retina.
Night scenes in the movies are often filmed in the daytime with dark filters used to darken the scene.
And, red filters in contacts or eyewear are most effective in preventing bleaching of the rod vision. Whether seen from ground or space, lights glare from the cities and suburbs, brightening the places we live, and spilling over into the places we sleep, and where the animals live. Now, ecologists and medical experts are wondering how this extra light affects our world and our health. For example, studies have linked light at night to human cancer and obesity, while other researchers have measured significant changes in animal behavior.
Christopher Kyba of the Free University of Berlin says they once made dark nights even darker, but now they reflect city light back to the surface.
With so many obvious benefits, the question of drawbacks was slow to arise, even as the number and intensity of light sources exploded. Body temperature, sleep, alertness, coordination and blood pressure are all part of the circadian cycle. Disturbances to the body clock cause jet-lag, and are implicated in night-time accidents and a number of diseases.
Stevens, who proposed in 1987 that light at night might play a role in the breast cancer pandemic2, says, “We thought it was related to diet. Thus evening light could affect not only sleep, but body temperature, blood pressure and glucose metabolism. When the sleep of volunteers was disrupted for a week, their blood had lower levels of the hormone leptin in the morning.
If red or green is less harmful than white, street lights could be “tuned” to benefit wildlife, though the bizarro color scheme might take some getting used to!


For example, the Urban Wildlands Group is working on wildlife-friendly lighting guidelines for the National Park Service. Great cover letters are key to getting your job application to the top of the candidate pile. Resumes, cover letters and other professional correspondence are crucial aspects of your job or internship search. If we look at the spectrum of light from the sun as it splits apart into a rainbow we see that "white" light is actually made of many different (colors) wavelengths from red on the outside to purple  and blue on the inside.
Thus red filters block the higher energy light and lets only the lower energy red light pass to the retina.
This allows the submariner’s eyes to replenish the rod photopigments before surfacing. This reduces the glare and bleaching of the rods, but allows the blue cone monochromat to still see with the blue channel.
Blue wavelengths severely inhibit the release of melatonin, a hormone that controls the daily metabolic cycles called the circadian rhythm. It’s not involved in vision, but seems to be the missing link between light and the body clock. Leptin is a chemical signal sent by fat cells that tells the body to stop eating; a low leptin level is essentially a hunger signal. The shift could increase competition among the mice and open an ecological niche to exotic species.
Normally, males, especially older ones, sing early in the morning to signal reproductive fitness and defend territory, comments Travis Longcore of the Urban Wildlands Group. If we use a red filter on a complete rod monochromat, we lessen the bleaching of the rods and allow these individuals to maintain functioning rods to see with in bright light. This protects the rod photopigments allowing the achromat to function in bright light that would otherwise overwhelm them. If not, the rods would be bleached out from the normal inside white lights and the submariner would not be able to spot risks from ships or planes as they surface.
Other colors, however, may offer  improvements in cosmetics or may be need to prevent blocking residual color vision in incomplete color loss. Because they have only one color channel, these individuals may not see blue color as we do, but may better see blue colored objects.
Although bright nights help predators hunt, their prey don’t get around much anymore and therefore have less time to feed, cutting their ability to reproduce. But although the study focused on sleep disruption, it also exposed the subjects to light when they awoke at night, Stevens says.
But they can be installed crappily, with no thought to where the light is going” or what type of light is best for the situation. Your rod cells quickly bleach out or saturate in bright light, leaving you in bright light without functioning photoreceptors. BCM patients have both rods and blue cones functioning but lack the red and green cone function. During the four-year experiment, specialists will study breeding birds, bats, other mammals, moths and vegetation. Stevens, Mutation Research 682 (2009) 1–6 ↩ Kloog I, et al, 2008, Light at night co-distributes with incident breast but not lung cancer in the female population of Israel.
The brighter the light, the faster and more severely the rods would bleach out, and the more you would struggle to see. Using a solid red filter on these patients may block some of the blue light from reaching the retina and the patient will loose their residual blue color vision. The study’s rigorous controls improve on existing observations, says Longcore, co-editor of a pioneering book on the ecology of light12. 65 (2005) 11174–11184 ↩Exposure to Room Light before Bedtime Suppresses Melatonin Onset …, Joshua J.



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