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The vast majority of devices containing LEDs are "safe under all conditions of normal use", and so are classified as "Class 1 LED product"/"LED Klasse 1". At present, only a few LEDs—extremely bright LEDs that also have a tightly focused viewing angle of 8° or less—could, in theory, cause temporary blindness, and so are classified as "Class 2". The opinion of the French Agency for Food, Environmental and Occupational Health & Safety (ANSES) of 2010, on the health issues concerning LEDs, suggested banning public use of lamps which were in the moderate Risk Group 2, especially those with a high blue component in places frequented by children. In general, laser safety regulations—and the "Class 1", "Class 2", etc. system—also apply to LEDs.

What type of LED can possibly cause blindness?
Answer: extremely bright LEDs
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To allow for greater movement while dancing and singing, Madonna was one of the earliest adopters of hands-free radio-frequency headset microphones, with the headset fastened over the ears or the top of the head, and the microphone capsule on a boom arm that extended to the mouth. Because of her prominent usage, the microphone design came to be known as the "Madonna mic". Metz noted that Madonna represents a paradox as she is often perceived as living her whole life as a performance. While her big-screen performances are panned, her live performances are critical successes. Madonna was the first artist to have her concert tours as reenactment of her music videos. Author Elin Diamond explained that reciprocally, the fact that images from Madonna's videos can be recreated in a live setting enhances the realism of the original videos. Thus her live performances have become the means by which mediatized representations are naturalized. Taraborrelli said that encompassing multimedia, latest technology and sound systems, Madonna's concerts and live performances are deemed as "extravagant show piece, a walking art show."

Who is first to have reenactment of her music videos in concerts?
Answer: Madonna
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The first scientific and literary journals were established during the Enlightenment. The first journal, the Parisian Journal des Sçavans, appeared in 1665. However, it was not until 1682 that periodicals began to be more widely produced. French and Latin were the dominant languages of publication, but there was also a steady demand for material in German and Dutch. There was generally low demand for English publications on the Continent, which was echoed by England's similar lack of desire for French works. Languages commanding less of an international market – such as Danish, Spanish and Portuguese – found journal success more difficult, and more often than not, a more international language was used instead. French slowly took over Latin's status as the lingua franca of learned circles. This in turn gave precedence to the publishing industry in Holland, where the vast majority of these French language periodicals were produced.

During which movement were the first scientific and literary journals established?
Answer:
the Enlightenment