The Doppler effect is observed whenever the source of waves is moving with respect to an observer. The Doppler effect can be described as the effect produced by a moving source of waves in which there is an apparent upward shift in frequency for observers towards whom the source is approaching and an apparent downward shift in frequency for observers from whom the source is receding. It is important to note that the effect does not result because of an actual change in the frequency of the source. Using the example above, the bug is still producing disturbances at a rate of 2 disturbances per second; it just appears to the observer whom the bug is approaching that the disturbances are being produced at a frequency greater than 2 disturbances/second. The effect is only observed because the distance between observer B and the bug is decreasing and the distance between observer A and the bug is increasing.
The Dopplereffect can be observed for any type of wave - water wave, sound wave, light wave, etc. We are most familiar with the Dopplereffect because of our experiences with sound waves. Perhaps you recall an instance in which a police car or emergency vehicle was traveling towards you on the highway. As the car approached with its siren blasting, the pitch of the siren sound (a measure of the siren’s frequency) was high; and then suddenly after the car passed by, the pitch of the siren sound was low. That was the Dopplereffect - an apparent shift in frequency for a sound wave produced by a moving source.
“The unsolved mysteries of the rainforest are formless and seductive. They are like unnamed islands hidden in the blank spaces of old maps, like dark shapes glimpsed descending the far wall of a reef into an abyss. They draw us forward and stir strange apprehensions. The unknown and prodigious are drugs to the scientific imagination, stirring insatiable hunger with a single taste. In our heart, we hope we will never discover everything. We pray that there will always be a world like this one at whose edge I sat in darkness. The rainforest and its richness is one of the last repositories on Earth of that timeless dream.”
— E.O. Wilson (via sciencesoup)
The world’s most powerful artificial tornado is part of the Mercedes-Benz Museum in Stuttgart, Germany. Though popular enough with visitors that the staff will bring out smoke generators to make it visible, the tornado was not built as an attraction - It’s actually part of the building’s fire protection system. The modern open design of the museum meant that conventional smoke removal systems were inadequate. Instead vorticity is generated in the central lobby with 144 wall-mounted jets. The angular velocity created by the jets is strongest at the middle, in the vortex core, due to conservation of angular momentum - exactly the way a spinning ice skater speeds up by pulling his arms in. The core of the vortex is a low pressure area, which draws outside air toward it - this is how the tornado pulls in smoke when there is a fire. The fan on the ceiling provides the pressure draw necessary for the smoke to be pulled up and out of the building at a supposed rate of 4 tons per minute. See the tornado in action here. (Photo credit: Mercedes-Benz Passion; submitted by Ivan)
Microneedle vaccineThis scanning electron micrograph (SEM) shows an array of ‘microneedles’ made from a biodegradable polymer. Researchers have shown these materials can be used to deliver vaccines and therapeutics to the outer layers of the skin in a safe and painless way. Because the microneedles avoid contact with blood vessels and nerve endings in the deeper skin layers, microneedle application prevents pain and the transmission of blood-borne pathogens. In addition, because the skin is so accessible, microneedle application can be performed quickly, requires minimal training for healthcare providers and makes self-application by patients possible. Each microneedle is approximately 700 microns high and 250 microns wide at the base.
Credit: Peter DeMuth / Wellcome Images
Golden Tortoise Beetle
Though it looks exceedingly pretty and jewel-like, this little beetle is actually incredibly metal. At just 5 to 8 millimetres long, the Golden Tortoise Beetle (Charidotella sexpunctata) is native to North America, found on plants such as sweet potato and morning glory. But upset one of these little guys and things change very quickly—they are the first known insect species to have the ability to rapidly change colour, not only when agitated but also during copulation (which, according to the very dedicated Edward M. Barrows of Georgetown University, can last anywhere from 15 to 583 minutes). The beetle has been observed to turn a variety of shades, from liquid gold to purplish to greenish gold to brownish to bright red. These colours are produced by an optical illusion: the beetle’s outer cuticle is transparent and it reflects light through a layer of liquid, and the beetles can alter the reflectivity of this liquid by using microscopic valves controlling moisture levels under their shell. Such reversible colour change is extremely rare, especially since the change is controlled: it’s elicited in response to specific events in their environment, whether it’s finding a mate or being annoyed by curious humans. Researchers speculate that it serves some interesting purposes, from defence (perhaps by mimicking ladybugs, which aren’t as tasty to their predators) to sexual signalling to mates. Be warned, though: if you catch one of these beetles, it will quickly turn a dark, dull brown, losing all the brilliant gold it had in life. To finish on an incredibly hardcore note: as larvae, the beetle has a fork-like structure hinged to its rear end, and will stick old skin and their own faeces to it, creating a shield for defence—otherwise known as a faecal parasol. Told you these little guys were metal.
i-dont-think-i-wanna-be-saved:
fucking amazing
Metal is clearly more of a family than anyone realizes
How can anyone not reblog this?
One of my favourite pictures on tumblr.
Omg
people think this genre of music is so mean and satanic but i think it is one of the more accepting kinds of music.
(Source: cineraria)
Bonding with my mother!
I’ve watched Doctor Who for a month or so. And I’m gettin’ my mother hooked on it!!
I mean, fair enough she doesn’t know Doctor Who since it doesn’t air in my country…. But god freaking yes, my mamma’s watching Doctor Who!
VICTORY DANCE!!
… He is making some very good points.
I’m going to start calling cow’s four legged boobs.
(Source: insertfandomreference)
When a solid object impacts on a liquid a cavity typically forms, entraining air into the pool. But this behavior varies widely according to the surface of the solid as well as the fluid’s properties. This video shows a sphere impacting a highly viscous liquid. The sphere stops shortly after impact while the cavity continues expanding in its wake. With a fluid like water, a long and thin cavity will typically pinch off before the object is decelerated, causing bubbles to form. No such behavior here. Instead the wide cavity pinches off at the surface of the motionless sphere and begins its rebound upwards. It even appears to pull the sphere partially back towards the surface! (Video credit: A. Le Goff et al.)
