Laser Hair Removal Really Turns Up The Heat

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Laser Hair Removal Really Turns Up The Heat

Since its arrival in the 1990s, laser hair removal has become one of the most popular cosmetic procedures in the world. It targets specific areas of a person's body with laser pulses, the energy of which is absorbed by the melanin molecules in hairs. This essentially overheats and damages the cells in the hair's follicle, preventing it from regrowing. The laser light has to be of an optimal wavelength to prevent its absorption by other molecules in the surrounding skin, which could cause burns.

08:22

from Veritasium

Key Facts to Know

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    Lasers used for hair removal deliver precise pulses in a matter of milliseconds. 1:18

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    Laser hair removal relies on the dark melanin in hairs to absorb laser light. 3:15

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    During a laser hair removal session, laser energy damages the cells inside hair follicles to prevent future hair growth. 4:49

Cats And Dogs Drink Very Differently

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Cats And Dogs Drink Very Differently

The most popular pets in the world might both drink from water bowls, but the ways in which they drink are quite different. In a general sense, dogs tend to be messier: they plunge their tongues past the surface of the water and curve them backwards into a scoop-shape, creating five times the acceleration of gravity as they pull them back into their mouths. This process creates a column of water that the dog catches and swallows. Cats, on the other hand, are a bit daintier. They don't go past the surface of the water with their tongues, preferring to lap without causing a splash. They pull up a smaller column of water, then close their mouths over it.

06:00

Key Facts to Know

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    Cats have spikes of keratin on their tongues called filiform papillae. 0:16

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    Watch a cat drink in slow motion: 0:46

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    Watch a dog drink in slow motion: 2:17

The Camera That Can Slow Down Light

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The Camera That Can Slow Down Light

Created by MIT Media Lab's Camera Culture group, this imaging system performs "Femto Photography." With an exposure time of about two trillionths of a second, it can indirectly depict how light travels in a single nanosecond, stretching the progress into a "movie" that is several seconds long. The movie is an indirect way of capturing the light because it actually consists of millions of separate recordings, each of which shows the light in a position that's slightly farther along than the last.

05:09

from NOVA PBS

Key Facts to Know

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    Researchers at MIT have created a camera with an exposure time of two trillionths of a second. 0:44

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    Watch a pulse of light move through a bottle with help from MIT's super high-speed camera: 1:29

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    Learn how an MIT camera can "see" around a corner: 3:41

How Do Cats Land On Their Feet?

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How Do Cats Land On Their Feet?

Cats begin to exhibit their righting reflexes when they're as young as three weeks old. Their flexible backbones enable them to twist in the air and land feet-first, all while conserving momentum. Counterintuitively, a cat falling from a high height-five stories or more-is more likely to survive than one falling from a lower height, as it has more time to adjust its position and brace for impact.

06:26

Key Facts to Know

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    When falling, cats first try to determine which way is up with their eyes or ears. 1:24

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    Cats with bobbed tails also land on their feet with the cat righting reflex. 2:49

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    Watch a labelled, slow-motion demonstration of the cat righting reflex: 4:31

Greyhound Vs Cheetah: Running In Slow-Motion

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Greyhound Vs Cheetah: Running In Slow-Motion

The cheetah is the fastest land animal on Earth, but the greyhound would leave it in the dust in a long-distance race. Cheetahs run for short sprints to catch prey, and are better than greyhounds at increasing the frequency of their stride to reach high speeds. Both animals run in similar styles, however, employing what's called a double-suspension gallop. This gait means that there are two points per stride during which all four feet are off the ground.

05:23

Key Facts to Know

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    Cheetahs are the fastest land animals on Earth. 0:22

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    See slow-motion footage of a running greyhound: 1:45

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    Cheetahs are better than greyhounds at increasing the frequency of their strides. 3:54