Best content in SciByte | Diigo

Tall, Devilish Storm Skids Across Mars' Surface - Science News - 0 views

www.sciencenews.org/...s_across_Mars%E2%80%99_surface

AprMedia mars tornado

shared by Mars Base on 10 Apr 12 - No Cached

Stretching 20 kilometers up from the planet’s surface
...

Cancel
dust devil recently caught in action on Mars
...

Cancel
What’s interesting about this dust devil is it’s very, very tall
...

Cancel
...3 more annotations...
To see one this size is very rare
...

Cancel
Mars Reconnaissance Orbiter took the lucky photograph using a high-resolution camera called HiRISE
...

Cancel
March 14, the camera spotted the dust devil leaving a trail across land in Mars’ northern hemisphere, where spring brings temperatures of up to -25° Celsius in some places
...

Cancel

Land Bridge Caused Wild Temperature Swings - ScienceNOW - 0 views

news.sciencemag.org/...e-caused-wild-temperature.html

scibyte42 BeringStrait

shared by Mars Base on 11 Apr 12 - No Cached

When the Bering Strait (box, lower left) was closed at the height of the last ice age, any sudden influx of fresh water to the North Atlantic couldn't flow through the Arctic Ocean to the North Pacific, making episodes of abrupt climate change much more likely.
...

Cancel
Much of the last ice age was characterized by violent climate swings
...

Cancel
beginning about 80,000 years ago, average temperatures in and around the North Atlantic rose or fell by 10°C or more in the course of a decade or two—a pattern that lasted for 70,000 years
...

Cancel
...24 more annotations...
a new study also points to a more earthbound culprit: the presence of a land bridge connecting Asia to North America.
...

Cancel
debated whether the climate swings were driven by sharp variations in solar activity or simply by unstable climatic processes
...

Cancel
Earth's climate has been relatively stable since the end of the last ice age
...

Cancel
temperatures were fairly stable, too, after the ice age began in earnest about 100,000 years ago
...

Cancel
20,000 years later, things became unhinged
...

Cancel
global sea level dropped to about 50 meters lower than it is today
...

Cancel
As the ice sheets that covered North America and northern Eurasia snatched up more and more of Earth's water
...

Cancel
exposed a broad strip of land that connected what is today Alaska and Siberia
...

Cancel
Ancient animals used the land bridge, which measured as much as 1500 kilometers wide in spots, to roam back and forth between Asia and North America
...

Cancel
also huge consequences for Earth's climate
...

Cancel
two sets of climate simulations
...

Cancel
one in which the Bering Strait was open
...

Cancel
one in which it was blocked
...

Cancel
each set of simulations, the researchers gradually added large amounts of fresh water to the North Atlantic between the latitudes of 20° and 50
...

Cancel
researchers propose, this swath, which spans the latitudes from southern Cuba to southern England, would have received large amounts of meltwater from Northern Hemisphere ice sheets during warm spells that occasionally punctuated the ice age
...

Cancel
Today, the surface waters in this swath affect the temperature and salinity of water even farther north in the Atlantic
...

Cancel
a region where surface waters cool, sink to the seafloor, and then flow southward—a critical link of the worldwide conveyor belt of ocean circulatio
...

Cancel
Gulf Stream, which brings climate-warming waters from the equator to the North Atlantic, comes to a halt.
...

Cancel
If waters of the far North Atlantic don't sink, says Hu, much of the large-scale ocean circulation worldwide temporarily collapses
...

Cancel
surface waters became so fresh that they never got denser than the underlying salty water, and therefore never sank
...

Cancel
shutting down ocean circulation and plunging areas around the North Atlantic, including Greenland, into a cold spell
...

Cancel
researchers noted a critical difference between the sets of simulations: When the Bering Strait was closed, it took as many as 1400 years for ocean circulation to recover; when the strait was open, the circulation rarely took more than 400 years to recuperate
...

Cancel
sign that ocean circulation is stable when the strait is open
...

Cancel
Whenever the ocean circulation shut down in the simulations, temperatures in Greenland suddenly dropped by 12°C—a decrease similar in magnitude to many abrupt cold snaps chronicled in the Greenland ice core records
...

Cancel

Eggs of enigmatic dinosaur discovered - 0 views

phys.org/...4-eggs-enigmatic-dinosaur.html

scibyte42 dinosaur

shared by Mars Base on 11 Apr 12 - No Cached

reported a 70 million years old pocket of fossilized bones and unique eggs of an enigmatic birdlike dinosaur in Patagonia.
...

Cancel
unique are the two eggs preserved near articulated bones of its hindlimb. This is the first time the eggs are found in a close proximity to skeletal remains of an alvarezsaurid dinosaur
...

Cancel
The dinosaur represents the latest survivor of its kind from Gondwana, the southern landmass in the Mesozoic Era
...

Cancel
...8 more annotations...
belongs to one of the most mysterious groups of dinosaurs, the Alvarezsauridae, and it is one of the largest members, 2.6 m, of the family
...

Cancel
The two eggs found together with the bones during the expedition might have been inside the oviducts of the Bonapartenykus female when the animal perished
...

Cancel
numerous eggshell fragments later found show considerable calcite resorption of the inner eggshell layer
...

Cancel
suggest that at least some of the eggs were incubated and contained embryos at an advanced stage of their development.
...

Cancel
analyzed the eggshells and found that it did not belong to any known category of the eggshell microstructure-based taxonomy
...

Cancel
a new egg-family, the Arraigadoolithidae
...

Cancel
using the electron scanning microscopy I observed unusual fossilized objects inside of the pneumatic canal of the eggshells
...

Cancel
the first evidence of fungal contamination of dinosaur eggs
...

Cancel

Bering Strait may be global temperature stabilizer - 0 views

phys.org/...al-temperature-stabilizer.html

scibyte42 BeringStrait

shared by Mars Base on 11 Apr 12 - No Cached

normally the AMOC causes cycling of warm water from the south to flow north, and cold water from the north to flow south
...

Cancel
engine for this system is cold salt laden water in the north sinking beneath incoming warm water
...

Cancel
If the cold water in the north is fresh, as it would be if it were coming from the melted glaciers, then it wouldn’t sink and the whole AMOC system would stop
...

Cancel
...2 more annotations...
if it stopped, air temperatures could change quickly.
...

Cancel
computer simulation actually showed the same temperature fluctuations over Greenland as researchers have found, via core ice samples, occurred the last time the Strait closed during the last Ice Age.
...

Cancel

Scientists find possible cause of movement defects in spinal muscular atrophy - 0 views

medicalxpress.com/...t-defects-spinal-muscular.html

scibyte42 medical SpinalMuscularAtrophy

shared by Mars Base on 11 Apr 12 - No Cached

abnormally low level of a protein in certain nerve cells is linked to movement problems that characterize the deadly childhood disorder spinal muscular atrophy, new research in animals suggests
...

Cancel
previous research has established the disease’s genetic link to SMN in motor neurons, scientists haven’t yet uncovered how this lack of SMN does so much damage
...

Cancel
showed in zebrafish that when SMN is missing – in cells throughout the body as well as in motor neurons specifically – levels of a protein called plastin 3 also decrease
...

Cancel
...15 more annotations...
When the researchers added plastin 3 back to motor neurons in zebrafish that were genetically altered so they couldn’t produce SMN, the zebrafish regained most of their swimming abilities movement that had been severely limited by their reduced SMN. These findings tied the presence of plastin 3 – alone, without SMN – to the recovery of lost movement
...

Cancel
without SMN in their cells still eventually died, so the addition of plastin 3 alone is not a therapeutic option
...

Cancel
using animal studies to pinpoint the role of plastin 3 in this disease
...

Cancel
In zebrafish genetically altered so they don’t produce SMN, plastin 3 levels remained low, as well.
...

Cancel
lowering plastin 3 first in the fish – SMN was unaffected. This showed that the plastin 3 decrease occurred only when SMN was lowered first
...

Cancel
SMN production was stimulated in zebrafish initially lacking the protein, plastin 3 levels were restored as well
...

Cancel
researchers determined that decreased SMN influences plastin 3 production at a late point in the process called translation, when amino acids are strung together to form the protein’s initial shape
...

Cancel
lack of SMN creates conditions in which too little plastin 3 is made to complete the protein’s normal functions – in these animals, the reduction was about four-fold
...

Cancel
maybe SMN is affecting translation of other proteins that could be contributing to spinal muscular atrophy
...

Cancel
That hasn’t been shown before
...

Cancel
examination of zebrafish motor neurons suggested that decreased plastin 3 affects these cells in at least two ways
...

Cancel
damaging axons, branch-like extensions that allow for communication among nerve cells
...

Cancel
destabilizing synapses, structures through which those signals pass
...

Cancel
result of the added plastin 3, the fish recovered their ability to turn and swim, movements they were previously unable to make.
...

Cancel
rescued axons, synaptic proteins and behavior all by putting plastin 3 back in motor neurons,” she said. “That’s very encouraging.”
...

Cancel