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Medical research on the effects of excessive light on the human body suggests that a variety of adverse health effects may be caused by light pollution or excessive light exposure, and some lighting design textbooks[34] use human health as an explicit criterion for proper interior lighting. Health effects of over-illumination or improper spectral composition of light may include: increased headache incidence, worker fatigue, medically defined stress, decrease in sexual function and increase in anxiety.[35][36][37][38] Likewise, animal models have been studied demonstrating unavoidable light to produce adverse effect on mood and anxiety.[39] For those who need to be awake at night, light at night also has an acute effect on alertness and mood.[40] Street light switched off for energy saving The light provided by a kerosene lamp is not very bright and is highly inefficient. Each kerosene lantern produces about 0.2% of the light that one would get for the same price in industrialized countries – about 2 to 4 lumens compared to 900 lumens produced by a 60 watt bulb. A common criticism of full cutoff lighting fixtures is that they are sometimes not as aesthetically pleasing to look at. This is most likely because historically there has not been a large market specifically for full cutoff fixtures, and because people typically like to see the source of illumination. Due to the specificity with their direction of light, full cutoff fixtures sometimes also require expertise to install for maximum effect. The Bluebird Library has been celebrating the lives of famous scientists. Each month, a new scientist is selected and displays are created to feature the discoveries and contribution of the scientist. April’s scientist of the month is Thomas Young; the library wishes to develop a Young’s experient display. The library has purchased a blue laser which emits light with a wavelength of 473 nm. They also have purchased a slide with a double slit; the slit spacing is 44 µm. The library’s current plans are to project the interference pattern onto a white board which is 3 feet wide and located 28 feet from the slits. What is the maximum number of bright spots which will appear on the board at these distances and what is the spacing distance between each bright spot? Assume that each bright spot is bright enough to see. (GIVEN: 1 m = 3.28 ft, 1 m = 106 mm, 1 m = 109 nm) Today I ended up checking everyones tail lights out in the parking lot. It all started when Kristin ask for help in repairing her inoperative brake likes. After fixing those we checked out all the lights on Kaias wagon and then my wife, Linda, drove in in her 1993 300D, so I decided to check those as well. Reducing light pollution implies many things, such as reducing sky glow, reducing glare, reducing light trespass, and reducing clutter. The method for best reducing light pollution, therefore, depends on exactly what the problem is in any given instance. Possible solutions include: If a street, traffic light or lit sign is dangerous or could cause physical damage, for example: Determine the frequency of … (GIVEN: 1 m = 109 nm) a. … red visible light (λ = 650 nm) b. … violet visible light (λ = 420 nm) The big bang model assumes that the universe is many billions of years old. While this timescale is sufficient for light to travel from distant galaxies to earth, it does not provide enough time for light to travel from one side of the visible universe to the other. At the time the light was emitted, supposedly 300,000 years after the big bang, space already had a uniform temperature over a range at least ten times larger than the distance that light could have travelled (called the ‘horizon’)11 So, how can these regions look the same, i.e. have the same temperature? How can one side of the visible universe ‘know’ about the other side if there has not been enough time for the information to be exchanged? This is called the ‘horizon problem’.12 Secular astronomers have proposed many possible solutions to it, but no satisfactory one has emerged to date (see Attempts to overcome the big bang’s ‘light-travel–time problem’). Some types of light sources are listed in order of energy efficiency in the table below (figures are approximate maintained values), and include relative visual skyglow impacts.[88][89] Use dim red lights for night lights. Red light has the least power to shift circadian rhythm and suppress melatonin. Light pollution has emerged as the widely accepted term for the negative or adverse effects of artificial nighttime illumination (Hölker et al., 2010 Hölker, F., Moss, T., Griefahn, B., Kloas, W., Voigt, C., Henckel, D., … Tockner, K. (2010). The dark side of light: A transdisciplinary research agenda for light pollution policy. Ecology and Society, 15(4), 13.10.5751/ES-03685-150413[Crossref], [Web of Science ®] [Google Scholar]). A central assumption of this paper is that the concept of light pollution—due to its increasing usage within professional, academic, and popular discourse—will substantially shape decisions about how to illuminate cities in the twenty-first century. In this role, it will actively inform the conditions for morally acceptable and desirable artificial nighttime illumination. Thus, to a large extent the concept of light pollution helps to provide a framing that addresses our new problem. This, however, necessitates an evaluation of the concept’s usefulness—its strengths and limitations. Its increasing usage must be coupled with critical reflection, if it is to offer an effective framing for ongoing policy efforts. In Policy Paradox, Stone (2002 Stone, D. (2002). Policy paradox: The art of political decision making. New York, NY: W. W. Norton & Company Inc. [Google Scholar]) discusses the complex issue of defining problems within political discourse. It is never an objective statement, but rather a strategic representation from one point of view that will promote a certain course of action. While problem definitions can act as a ‘… vehicle for expressing moral values … there is no universal technical language of problem definition that yields morally correct answers’ (p. 134). Nonetheless, focusing on how a problem is defined can help us see the situation from multiple perspectives and identify assumptions about facts and values embedded therein (Stone, 2002 Stone, D. (2002). Policy paradox: The art of political decision making. New York, NY: W. W. Norton & Company Inc. [Google Scholar]). This can, in turn, help to strengthen the problem definition. About 1.7 billion people or more than a fifth of the world’s population are without access to electricity and modern lighting. The problem is most severe in rural areas or on the fringes of cities. , however the extent to rural electrification varies widely from country to country.  For example, 90% of Africa is not served by grid electricity versus 20% of Mexico. In fact, some African countries, for example, Rwanda and Burundi have barely passed the 1% electrification threshold! You can report a non-urgent fault with a street light by using the ‘Report now’ button below or phoning the Fault Line on 0845 601 0939, Monday to Friday from 8am to 5pm.  Please enter any additional information that may help our technician locate the light for repair. Light pollution is a side-effect of industrial civilization. Its sources include building exterior and interior lighting, advertising, outdoor area lighting (e.g. car parks/parking lots), offices, factories, streetlights, and illuminated sporting venues. It is most severe in highly industrialized, densely populated areas of North America, Europe, and Japan and in major cities in the Middle East and North Africa like Tehran and Cairo, but even relatively small amounts of light can be noticed and create problems. Awareness of the deleterious effects of light pollution began early in the 20th Century (see e.g. Beston[8]), but efforts to address effects did not begin until the 1950s.[9] In the 1980s a global dark-sky movement emerged with the founding of the International Dark-Sky Association (IDA). There are now such educational and advocacy organizations in many countries worldwide. vigrx Maxman Penigen 500 Testogen BeMass el macho TestX Core Penigen 500 Maxman BeMass