Saturday, April 29, 2017

April 2017 Solar Flares - UNIVERSE

The sun emitted a trio of mid-level solar flares on April 2-3, 2017. NASA’s Solar Dynamics Observatory, which watches the sun constantly, captured images of the three events.

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The Holographic Principle - PHYSICS

Is this picture worth a thousand words? According to the Holographic Principle, the most information you can get from this image is about 3 x 1065 bits for a normal sized computer monitor. The Holographic Principle, yet unproven, states that there is a maximum amount of information content held by regions adjacent to any surface. Therefore, counter-intuitively, the information content inside a room depends not on the volume of the room but on the area of the bounding walls.

The principle derives from the idea that the Planck length, the length scale where quantum mechanics begins to dominate classical gravity, is one side of an area that can hold only about one bit of information. The limit was first postulated by physicist Gerard 't Hooft in 1993. It can arise from generalizations from seemingly distant speculation that the information held by a black hole is determined not by its enclosed volume but by the surface area of its event horizon. The term "holographic" arises from a hologram analogy where three-dimension images are created by projecting light though a flat screen. Beware, other people looking at the featured image may not claim to see 3 x 1065 bits -- they might claim to see a teapot.

Image & info via APOD
Image Credit: Caltech

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Friday, April 28, 2017

Hercules Beetle pupa - BIODIVERSITY

Hercules beetles are a form of rhinoceros beetle that can reach more than 17cm long. They transform larvae to a pupa stage.

Once hatched from its egg, the larva spends up to two years tunneling/eating rotting wood; the larva looks like a large white caterpillar.

Once they have stored enough energy they will turn into a hard shell and morph into the beetle, when the beetle is ready to come out they will moult (shed) their shell and emerge an adult.


The footage was shared online by Ziya Tong, the host of a TV nature program in Canada called Daily Planet.

Two Million Stars on the Move - UNIVERSE

If you could watch the night sky for one million years -- how would it change? Besides local effects caused by the Earth's spin and the reorientation of the Earth's spin axis, the stars themselves will move. Combining positional data of unprecedented accuracy for two-million stars taken over years by ESA's Earth-orbiting Hipparcos (now defunct) and Gaia satellites, a future extrapolation of star movements was made over millions years.

Many stars make only small angular adjustments, but some stars -- typically those nearby -- will zip across the sky. Once familiar constellations and asterisms will become unrecognizable as the bright stars that formed them move around. Not shown  are many local nebulas that will surely dissipate while new ones will likely form in different places. Perhaps reassuringly, future Earth inhabitants will still be able to recognize the central band of our Milky Way Galaxy.

Image & info via APOD
Video Credit: ESA, Gaia, DPAC

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Thursday, April 27, 2017

Alien: Covenant | Prologue: The Crossing | 20th Century FOX

The bubble-like shape of the heliosphere observed by Voyager and Cassini - UNIVERSE

New data from NASA’s Cassini mission, combined with measurements from the two Voyager spacecraft and NASA’s Interstellar Boundary Explorer, or IBEX, suggests that our sun and planets are surrounded by a giant, rounded system of magnetic field from the sun — calling into question the alternate view of the solar magnetic fields trailing behind the sun in the shape of a long comet tail.

The sun releases a constant outflow of magnetic solar material — called the solar wind — that fills the inner solar system, reaching far past the orbit of Neptune. This solar wind creates a bubble, some 23 billion miles across, called the heliosphere. Our entire solar system, including the heliosphere, moves through interstellar space.

The prevalent picture of the heliosphere was one of comet-shaped structure, with a rounded head and an extended tail. But new data covering an entire 11-year solar activity cycle show that may not be the case: the heliosphere may be rounded on both ends, making its shape almost spherical.
A paper on these results was published in Nature Astronomy on April 24, 2017.

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The image on the left shows a compact model of the heliosphere, supported by this latest data, while the image on the right shows an alternate model with an extended tail. The main difference is the new model’s lack of a trailing, comet-like tail on one side of the heliosphere. This tail is shown in the old model in light blue.
Credits: Dialynas, et al. (left); NASA (right)

Here’s Why You Don’t Feel Jet-Lagged When You Run a Fever - NEUROSCIENCE

A clump of just a few thousand brain cells, no bigger than a mustard seed, controls the daily ebb and flow of most bodily processes in mammals — sleep/wake cycles, most notably. Johns Hopkins scientists report direct evidence in mice for how those cell clusters control sleep and relay light cues about night and day throughout the body.

“Light has a strong, negative and direct effect on sleep in humans. We experience this every evening when we turn out the lights before we go to bed and every morning when we open the curtains to let light in. However, very little was known about how this happens. Learning that the SCN (suprachiasmatic nucleus) is indeed required for light to directly regulate sleep is an important piece of the circadian rhythm puzzle,” says Seth Blackshaw, Ph.D., professor of neuroscience at the Johns Hopkins University School of Medicine. “Our chances of finding treatments for people with sleep disorders, or just jet lag, improve the more we understand the details about how sleep is controlled.”

Blackshaw says scientists have known for a while that the SCN functions as a master clock to synchronize sleep and other so-called circadian rhythms in humans and other mammals. But its importance in the more immediate regulation of sleep, like when a bright light wakes someone up, remained debatable because the experiments needed to show its role in a living animal were essentially impossible. “If you surgically removed the SCN in mice, their sleeping and waking were no longer immediately influenced by light, but you can’t remove the SCN without also severing the optic nerve that brings light information to it from the retina. So no one knew if this resistance to light was due to the missing SCN or the missing optic nerve,” says Blackshaw.

In experiments first reported several years ago, Blackshaw’s team found a way to disrupt the normal function of the SCN without physically removing it and damaging the optic nerve. The researchers were trying to identify genes involved in the development of the mouse hypothalamus, the area of the brain that includes the SCN. They identified one such gene, dubbed LHX1, that seemed to be the earliest to “turn on” in the development of the fetal SCN.

For the new round of experiments, the scientists used a customized genetic tool to delete LHX1 just from cells that make up the SCN. They found that the mice experienced severely disrupted circadian rhythms, although they could still be weakly synchronized to light cycles. And the cells of the SCN no longer produced six small signaling proteins known to coordinate and reinforce their efforts, a biochemical process known as coupling.

Whether the mice were kept in constant light, constant darkness or normal cycles of both, their sleep times and duration became random. Cumulatively, they slept for the same amount of time, about 12 hours each 24-hour period, like normal mice, but there was no pattern to the cycle.

“This experiment showed that the SCN is critical to light’s immediate effect on sleep,” says Blackshaw.

The scientists also noticed that in the SCN-impaired mice, core body temperatures didn’t cycle normally. The average body temperature for humans is 37 degrees Celsius, but it fluctuates throughout the day by about 1 degree Celsius, being highest in the afternoon and lowest just before dawn. A similar pattern occurs in mice. These small temperature fluctuations can have a big influence on processes that occur outside the brain that are also under circadian control, such as glucose usage and fat storage, and it has been speculated that they may be the main way by which the SCN controls these bodily rhythms.

In contrast, one of the hallmarks of the body’s circadian processes, including cycles in core body temperature, is that they aren’t generally disturbed by large temperature changes. “Otherwise, you would feel jet-lagged every time you got a fever,” says Blackshaw.

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The area of the brain known as the suprachiasmatic nucleus (SCN) is the body’s master clock. It uses light to synchronize the body’s rhythms with night and day. It directly controls sleep/wake cycles and indirectly controls other processes, like hunger and thirst, by controlling the body’s thermostat, the preoptic area of the brain.
Credit: Johns Hopkins Medicine

Corian Marinescu

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