Tuesday 30 April 2013

Team identifies the sounds made by drought-stressed trees.




A tree stands alone in the drought-stricken Salmon-Challis National Forest, Idaho, in an undated picture.


 

When drought hits, trees can suffer—a process that makes sounds. Now, scientists may have found the key to understanding these cries for help.

In the lab, a team of French scientists has captured the ultrasonic noise made by bubbles forming inside water-stressed trees. Because trees also make noises that aren't related to drought impacts, scientists hadn't before been able to discern which sounds are most worrisome. (Watch a video: Drought 101.)

"With this experiment we start to understand the origin of acoustic events in trees," said Alexandre Ponomarenko, a physicist at Grenoble University in France, whose team conducted the research.

This discovery could help scientists figure out when trees are parched and need emergency watering, added Ponomarenko, who presented his team's results last month at an American Physical Society meeting in Baltimore, Maryland.

Listening to Trees

To figure out how to listen to trees, the French scientists drew on their knowledge of how trees take in water—essentially by drinking from a really long "straw."

Inside tree trunks are bundles of specialized tubes called xylem, which rely on the attractive forces between water molecules as well as those between water and plant cells to lift liquid to the highest leaves and branches. (See National Geographic's tree pictures.)

Because trees are so tall, the liquid in the xylem can be under intense pressure—many times that of the atmosphere around us—but the attractive forces between neighboring water molecules keep the water column intact.

Imagine using a straw to slurp the last few drops from the bottom of your glass: You have to increase the pressure even more. In drought-stricken trees, this increased pressure can cause the water column to break, allowing dissolved air to form bubbles that block water flow.

These events are called cavitations, and while trees can withstand some, too many can be deadly.

Since cavitations can kill trees, scientists and forest managers want to know when they are increasing. (Also see "Pictures: Saving and Studying Tasmania's Giant Trees.")

Scientists have known for decades that microphones can pick up the noises that cavitations make. But because they couldn't see inside the tree, they weren't certain of the origins of these sounds, which could have resulted from wood creaking or breaking or xylem cells collapsing.

To answer the question, the team put a thin slice of pine wood into a liquid-filled gel capsule to mimic conditions inside a living tree.

The scientists then evaporated water from the gel, simulating a drought. As the wood began cavitating, the scientists filmed bubbles forming while recording with a microphone.

The scientists found that around half the sounds they picked up were associated with cavitations. The rest were from other processes, such as bubbles invading neighboring cells. Most important, the sound waves from each type of event made a distinct pattern. All of them are above the range of human hearing.

The researchers think they can compare sounds from living trees with these patterns, and determine which processes are creating the sounds.

Helping Thirsty Trees

According to Ponomarenko, the findings could lead to the design of a handheld device that allows people to diagnose stressed trees using only microphones.

Such a device may be particularly important if droughts become more common and more severe, as many global warming models predict they will. (Read "The New Dust Bowl" in National Geographic magazine.)

In fact, a study published in Nature last fall suggested that trees in many places—from tropical rain forests in South America to arid woodlands in the U.S. West—already "live on the edge," meaning their cavitation rate is almost as high as they can sustain.

Ponomarenko's method could provide an early warning that cavitations are increasing.

For instance, he envisions a device that would attach to a tree and constantly listen for sounds of thirst. If needed, the device could then trigger an emergency-watering system.

Ponomarenko's research is promising, added Cornell University's Abe Stroock, whose lab designed the gel capsule the French team used. He said the result "opens a new mode of observation" into cavitation. (See pictures of the 2012 drought that parched much of the United States.)

But he also noted that the wood samples used in the team's study had to be "excised and abused," so they don't necessarily behave exactly like wood in a living tree.

"Translating [these findings] to a living plant and into different species is a lot of work, potentially," he said.
World's Deadliest: Superfast Flyer Makes a Kill


When the peregrine falcon dives for prey, birds in mid-flight don't stand a chance
World's Deadliest: Rattlesnake vs. Hawk


This desert showdown pits brains against brawn. Using its wings as a distraction, can a hawk bring down a venomous rattler?
World's Deadliest: "Sudden Death" Cuttlefish:










Crustaceans beware: That piece of coral might be a camouflaged cuttlefish looking for a quick bite.


Predicting Meteorite Impacts:




February 15, 2013—Astrobiologist and National Geographic Emerging Explorer Kevin Hand explains how Asteroid DA-14 could be only the beginning of what we can expect from space. With more than a million such objects out there, what can be done to prevent a meteor strike like the one that crashed into Russia this morning?





  Penguins: No Fail at Mealtime:



January 29, 2013—Japanese researchers, using cameras strapped to the backs of Adelie penguins in Antarctica, showed a perfect success rate at catching prey underwater.

Coelacanth Genes Mapped, "Living Fossil" Evolved Slowly:

 A coelacanth poses for its portrait in South Africa's Sodwana Bay.

In the deep sea, slow and steady wins the race—and that proverb is reflected in the genes of the coelacanth (Latimeria chalumnae), a new study says.

When the study authors sequenced the ancient fish's genome, they found that its genes have been evolving more slowly than the genes of the other fish or terrestrial vertebrates they looked at, including sharks, chickens, and lungfish. (Also see "Coelacanths Can Live Past 100, Don't Show Age?")

In the paper, published April 18 in the journal Nature, the researchers speculate that the coelacanth's relatively unchanged deep-sea habitat, and an apparent lack of predation over thousands to millions of years, means this ancient fish didn't need to change much to survive. (See more pictures of deep-sea creatures.)

"Living Fossil" Fish Revealed


Coelacanths live as deep as 2,300 feet (700 meters) below the sea surface, and can reach 6.5 feet (2 meters) in length.

Often referred to as a "living fossil," the coelacanth looks remarkably similar to its fossil relatives from 300 million years ago. (See more pictures of this ancient-looking fish.)

Scientists had thought the coelacanth (pronounced SEE-la-kanth) had gone extinct about 65 to 70 million years ago until a researcher stumbled on a freshly caught specimen off the coast of South Africa in 1938.

And since its discovery, about 300 individuals have been recorded in two areas in the world—near the Comoros Islands (map) off the eastern coast of Africa and in the waters near Sulawesi, Indonesia (map).

A second living species of coelacanth, Latimeria menadoensis, was also discovered in 1997 off the coast of Indonesia. (Related: "New Species: 'Rebel' Coelacanth Stalked Ancient Seas.")




Northern Hemisphere observers can watch event via live feed.

 A partial lunar eclipse is seen from Loudwater, England, in 2011.

The full moon will get a tiny bite taken out of today as it undergoes one of the shallowest and shortest partial eclipses of this century. (See lunar eclipse pictures.)

Though the celestial phenomenon will be visible only in the Eastern Hemisphere, armchair astronomers can watch a live feed of the eclipse thanks to SLOOH. The Internet-based space-tracking service is broadcasting the eclipse with its robotic telescopes on the Canary Islands (map) starting at 3 p.m. ET on April 25.





What is a lunar eclipse?
A lunar eclipse occurs when the sun, Earth, and moon align. During total lunar eclipses, the entire moon is engulfed in Earth's darkest shadow. But during partial eclipses, the moon never completely goes dark or turns red—only a portion of its disk appears to go dim. (Read about a total lunar eclipse in 2011.)

"In this case, the moon only just clips the edge of the deepest part of the shadow, called the umbra," said Mark Hammergren, an astronomer at Adler Planetarium in Chicago, Illinois.

"The entire northern half of the moon will be slightly darkened by the penumbra, a broader, less intense area of the Earth's shadow."

Who will see it?


While North America will be left out of the sky show, much of the Eastern Hemisphere can see Earth's shadow brush across the outer half of the moon's surface over the course of the four-hour event. (Take a moon myths and mysteries quiz.)

All the stages of the eclipse will be visible across the Indian Ocean, central Asia, western Australia, Africa, and Europe.

Because only a tiny fraction of the moon's disk will dip into the darkest shadow cone, the entire partial eclipse phase will be a challenge to observe, lasting less than a half hour for viewers, Hammergren said.

"This eclipse is distinguished, or undistinguished, by being the second shortest partial eclipse of the moon in the 21st century, lasting only about 27 minutes," he said.

When is best to watch?

The most readily visible part of the eclipse will begin at 3:54 p.m. ET, just as the moon is straight overhead for observers in the Indian Ocean.

The deepest and most interesting part of the eclipse—during which Earth's shadow will fall on less than 2 percent of the tiny sliver of the moon's disk—occurs at 4:07 p.m. ET and leaves the umbra at 4:21 p.m.

What if I miss this one?

Generally, between two and four lunar eclipses occur each year, but ones as slight as tomorrow's are rare. (Read about a 2012 lunar eclipse that occurred during a supermoon.)

The last time such a small partial lunar eclipse occurred was in 1958, and another one like it won't occur until 2034.

But don't fret: Later this year, two more partial lunar eclipses will be visible on May 25 and October 18.
Space Pictures This Week: Nebulae, Rockets, and a New Earth

 

This Hubble Space Telescope shot of the Horsehead Nebula, released April 19, was taken in celebration of the telescope's 23rd anniversary. Pictured in infrared wavelengths for the first time, the Horsehead is part of the larger constellation Orion.

The nebula is relatively close—just 1,500 light-years from Earth—which makes it a favorite for space photography focused on the formation of new stars. NASA scientists anticipate that despite Hubble's crystal-clear view, the new James Webb Space Telescope that will launch in 2018 will provide even more detailed views.





 

Top 10 Amazing Earth Facts:


As well known and well traveled as our planet is, there are still new things being discovered every day. In fact, most of our oceans haven’t even been explored yet which is why when new depths are located; they often come with hundreds of new species. Rain forests offer up new animals and plants as often as we can explore them. The Earth is constantly changing, shifting, and exposing new secrets for humans to marvel at. It took many years and many great minds to solve the problem of getting through Earth’s atmosphere into the wide expanse of space beyond. Here are ten amazing facts about our home that you may not be aware of.

 10. The Atmosphere:

Many layers of atmosphere coat our planet including the mesosphere, ionosphere, exosphere, and the thermosphere, but it’s the troposphere, closest to the planet itself, that supports our lives and is, in fact, the thinnest at only about 10 miles high.

9. Deserts:

Believe it or not, most of the Earth’s deserts are not composed entirely of sand. Much, about 85% of them, are rocks and gravel. The largest, the Sahara, fills about 1/3 of Africa (and it is growing constantly) which would nearly fill the continental United States.

8. The Big Blue Marble:

The Earth is, in fact, not really round. It is called an oblate spheroid meaning it’s slightly flattened on the top and bottom poles.

7. Salty Oceans:

If you could evaporate all the water out of all the oceans and spread the resulting salt over all the land on Earth, you would have a five hundred-foot layer coating everything.


6. Lakes and Seas:

The largest inland sea (or, sometimes called a lake) is the Caspian Sea which is on the border of Iran and Russia.


5. Mountains:


 The Andes Mountain range in South America is 4,525 miles long and ranks, as the world’s longest. Second Longest: The Rockies; Third: Himalayas; Fourth: The Great Dividing Range in Australia; Fifth: Trans-Antarctic Mountains. For every 980 feet you climb up a mountain, the temperature drops 3-1/2 degrees.

4. Deep Water:
The deepest lake in the world is in the former USSR and it is Lake Baikal. It has a length of 400 miles, a width of roughly 30, but its depth is just over a mile: 5,371 feet down. It is deep enough, so is speculated, that all five of the next largest lakes: The Great Lakes could be emptied into it.

3. Shaky Ground:

Earthquakes can be catastrophically destructive and many a year are deadly. However, the Earth releases about 1 million a year, almost all are never even registered.

2. Hot, Hot, Hot:
Most people believe that Death Valley, California, U.S.A. is the hottest place on Earth. Well, occasionally it is, but the hottest recorded temperature was from Azizia in Libya recording a temperature of 136 degrees Fahrenheit (57.8 Celsius) on Sept. 13, 1922. In Death Valley, it got up to 134 Fahrenheit on July 10, 1913.

1. Dust in the Wind:
Experts from the USGS claim that roughly 1,000 tons of space debris rains down on Earth every year.














 

Saturday 27 April 2013

 Red-winged Blackbird:

The Red-winged Blackbird (Agelaius phoeniceus) is a passerine bird of the family Icteridae found in most of North and much of Central America. It breeds from Alaska and Newfoundland south to Florida, the Gulf of Mexico, Mexico, and Guatemala, with isolated populations in western El Salvador, northwestern Honduras, and northwestern Costa Rica.

It may winter as far north as Pennsylvania and British Columbia, but northern populations are generally migratory, moving south to Mexico and the southern United States.
Claims have been made that it is the most abundant and best studied living bird in North America.

The Red-winged Blackbird is sexually dimorphic; the male is all black with a red shoulder and yellow wing bar, while the female is a nondescript dark brown. Seeds and insects make up the bulk of the Red-winged Blackbird's diet.
Cool Slow Motion Male Anna's Hummingbird:

Anna's Hummingbird (Calypte anna) is a medium-sized hummingbird native to the west coast of North America. This bird was named after Anna Masséna, Duchess of Rivoli.


Anna's Hummingbird is 3.9 to 4.3 inches (10 to 11 centimeters) long. It has a bronze-green back, a pale grey chest and belly, and green flanks. Its bill is long, straight and slender.

The adult male has an iridescent crimson-red crown and throat, and a dark, slightly forked tail. Anna's is the only North American hummingbird species with a red crown. Females and juveniles have a green crown, a grey throat with some red markings, a grey chest and belly, and a dark, rounded tail with white tips on the outer feathers.

These birds feed on nectar from flowers using a long extendable tongue. They also consume small insects caught in flight. A PBS documentary that first aired January 10, 2010, shows how Anna's Hummingbirds eat flying insects (at 16:45). They aim for the flying insect, then open their beaks very wide. That technique has a greater success rate than trying to aim the end of a long beak at the insect.

While collecting nectar, they also assist in plant pollination. This species sometimes consumes tree sap
 This Bird Can Copy The Sound OF Everybody:

A Lyrebird is either of two species of ground-dwelling Australian birds, that form the genus, Menura, and the family Menuridae. They are most notable for their superb ability to mimic natural and artificial sounds from their environment. Lyrebirds have unique plumes of neutral coloured tailfeathers.

Lyrebirds are among Australia's best-known native birds. As well as their extraordinary mimicking ability, lyrebirds are notable because of the striking beauty of the male bird's huge tail when it is fanned out in display; and also because of their courtship display.
Why Do Dolphins Love Pregnant Women?

Because they know they are pregnant through use of their sonar abilities and are excited by the discovery.


For Other Uses, See Dolphin:


Dolphins are marine mammals closely related to whales and porpoises. There are almost forty species of dolphin in 17 genera.

They vary in size from 1.2 m (4 ft) and 40 kg (90 lb) (Maui's dolphin), up to 9.5 m (30 ft) and 10 tonnes (9.8 long tons; 11 short tons) (the orca or killer whale).

They are found worldwide, mostly in the shallower seas of the continental shelves, and are carnivores, eating mostly fish and squid.

The family Delphinidae is the largest in the Cetacean order, and evolved relatively recently, about ten million years ago, during the Miocene.

Dolphins are among the most intelligent animals, and their often friendly appearance, an artifact of the "smile" of their mouthline, and seemingly playful attitude have made them very popular in human culture.


See list of sources below: 

 Both of these animals are powerful and fierce carnivores. But scientists say that in a fight between a Bengal tiger and an African lion, there is a 90% chance that the Tiger will win.

It is a well-known fact that tigers are the biggest cats in the world. Not only this, but tigers are noticeably more muscular, and better fighters. It is actually a myth that lions are better fighters than tigers, because tigers compete with each other for territory just as much as lions fight for a pride.


Tigers also have experience fighting with many animals; Bengal Tigers can easily kill large crocodiles and black bears, and Siberian tigers have been known to attack and kill huge adult brown bears. Tigers have been noticed as better fighters because they are more swift, agile, fierce, and have better eye-coordination. They have a stronger jaw force and paw-swipe. However, it is not true that tigers have longer fangs than lions. The skulls of these two cats have been compared, and usually their canines are about the same.


 The term "King" comes from the fact that a lion's mane looks like a crown, and the fact that they rule a pride. A lion's mane can offer it protection from bites to the neck. This is especially helpful when facing hyenas, which have a very deadly bite. However, a tiger will not always go for the lion's neck, but instead will usually attack it's limbs, eyes, head, and face. And the difference between the two cats' lifestyles adds on to which is more intelligent: Living a solitary life results in the tiger being more cunning.

The tiger also hunts larger prey than the lion. The largest prey that lions hunt is the African buffalow, a species of African cattle. Tigers, however, are excellent at hunting guar, which is the largest type of cattle in the world. There are also differences in the way the two animals fight. Lions tend to stand on three legs, and use one paw to fight. Tigers normally balance on their hind legs and use both front paws to fight, giving them a huge advantage.

Tigers also use "trickery", keep their heads back, and use well thought-out moves when fighting, while lions are known for blindly charging. Another important feature in how well the animals fight is the way their bodies are built. Lions are built more stiffly than tigers, and their bodies are more compact. Lions sometimes appear more muscular in the forelimbs, but tigers simply have more fur covering their muscles, so they are harder to see. Tigers also have more flexible muscles then lions.

The lion DOES have an advantage though: courage. Lions are braver, and less likely to back down from a fight. There have been reports of tigers submitting to lions when they meet in reserves, so they can avoid injury. But if the lion refuses to leave the tiger alone, than the tiger is probably going to end up victorious. Within the Bengal Tiger scientists found a most disturbing ferocity. When it comes to the decision to fight, this cat attacks violently, most often winning in any fight against a lion.

In the end, the tiger's agility and accuracy comes out on top. 80% of experts agree that the tiger is the dominate cat. But not only National Geographic reporters say so.

The larger tiger is more powerful than the lion.

Friday 26 April 2013



This Nudibranch Displays A Stunning Set Of Colors


The body is purple, the cerata are orange and the rhinophores are scarlet. 
The neon orange appendages on the back of Flabellina iodinea are the cerata which extract oxygen from the sea water they live in.
The cerata are also extensions of the digestive system, and are used to store the stinging cells of the anemones and fan-like hydroids they eat. 
The red rhinophores are sensory structures used for detecting the presence of possible mates and prey. The purple, red, and orange colors are derived from a single carotenoid pigment, astaxanthin.
The pigment appears in three modified states, leading to the three distinct colors.
Scientists guess the reason why the Spanish Shawl's gills are orange is so they can camouflage with their prey while they are eating.
The orange gills on their backs are also a warning to potential predators. The color tells their predators that they are either poisonous or distasteful.

Cats: World's Deadliest: Lion Pack vs. Buffalo 

A Cape buffalo can outweigh a single lion five to one. Can some reinforcements tip the scale in the lions' favor?

 

Thursday 25 April 2013

Rare Video of Endangered Shorebird:

March 5, 2013—Researchers with the Cornell Lab of Ornithology capture video of newborn Spoon Billed Sandpiper chicks. This critically endangered Asian shorebird could go extinct within ten years.











World's Largest Spider:

The goliath birdeater tarantula of South America is arguably the biggest spider in the world. Watch as one hapless mouse wanders into a spider's deadly trap, and see the unusual adaptations that make the goliath one of nature's deadliest ambushers.

 SPIDER BITE:

A spider bite is an injury resulting from the bites of spiders or other closely related arachnids.

Spiders are active hunters and rely heavily on their bites to paralyze and kill their prey before consuming it. They also bite in self-defense. While many spiders will never attack animals larger than themselves, some—e.g., Atrax robustus—exhibit a rather aggressive behavior and will stand their ground when approached by larger animals. Most spider bites occur when humans unintentionally press up against spiders and receive a defensive bite. On rare occasions, spiders may make prey mistakes and bite a human finger or other body part as though it were a caterpillar or other such insect.

Only spiders of fairly large species possess chelicera long enough to penetrate human skin, and most of those are females. The effect of a bite on humans is dependent on both the toxicity of the venom and the amount of venom. About 98% of the bites inflicted by species that are large enough that their bites are noticed will have no serious medical consequences. Of those bites that humans notice, venoms can include necrotic agents, neurotoxins, and agents such as serotonin. Only some two hundred species in twenty genera (out of over 40,000 known species) are known to have serious, potentially lethal bites.

In most cases of bites, the chief concern is the spider's venom, although in some cases medically non-significant spiders can transmit infectious diseases. Spiders regarded as dangerous possess venom that is sufficiently toxic to humans that a single bite can deliver a medically significant dose. Only two spider families, Uloboridae and Holarchaeidae, are known to be non-venomous, i.e., lacking venom glands; however, their fangs can inflict infections spread through the skin, which in theory could represent more danger than from bites of non-lethal venomous spiders.

Spider bites may be misdiagnosed by both the general public and medical practitioners. Many other conditions, both infectious and non-infectious can be confused with spider bites. Many of these conditions are far more common and more likely to be the source of necrotic wounds.

SIGNS AND SYMPTOMS:

Pain from non-venomous spider bites typically lasts for 5 to 60 minutes while pain from venomous spider bites frequently lasts for longer than 24 hours. The rate of a bacterial infection due to a spider bite is low (0.9%).







Wednesday 24 April 2013

The first images and video of a giant squid swimming in the ocean depths has been captured by a Japanese-led group of scientists, with support from the Japanese national broadcaster NHK and the Discovery Channel.


The squid was on the small side – only about 3 meters (10 feet) long. The largest ever found measured about 18 meters. The giant mollusk’s eyes are the size of a human head and it can weigh up to a ton.

Little is known about the giant squid, also believed to be the mythical Kraken in folk-lore stories. Researchers have searched for the real creature for years in hopes of learning more about the species.

Giant squid have been found washed ashore but never fully observed in the ocean. No one has caught the beast on film in its natural habitat like this.

This cephalopod was found near the Ogasawara Islands, south of Tokyo.

Giant squid are very elusive, solitary and shy animals.

The crew spent hours in a small submersible that used lights invisible to both human and squid eyes.

At 630 meters, they lured giant squid using small squid as bait. After about 100 dives, the giant squid appeared. The sub followed it down to 900 meters (3,000 feet).

The footage will be aired for the first time in the Discovery Channel’s “Monster Squid: The Giant is Real.” The program premieres on Discovery at 8 p.m. ET Jan. 27th.

Friday 19 April 2013

Environmental history is the study of human interaction with the natural world over time.  In contrast to other historical disciplines, it emphasizes the active role nature plays in influencing human affairs. Environmental historians study how humans both shape their environment and are shaped by it.

Environmental history emerged in the United States out of the environmental movement of the 1960s and 1970s, and much of its impetus still stems from present-day global environmental concerns.

The field was founded on conservation issues but has broadened in scope to include more general social and scientific history and may deal with cities, population or sustainable development. As all history occurs in the natural world, environmental history tends to focus on particular time-scales, geographic regions, or key themes.

It is also a strongly multidisciplinary subject that draws widely on both the humanities and natural science.The subject matter of environmental history can be divided into three main components.

The first, nature itself and its change over time, includes the physical impact of humans on the Earth's land, water, atmosphere and biosphere. The second category, how humans use nature, includes the environmental consequences of increasing population, more effective technology and changing patterns of production and consumption.

Other key themes are the transition from nomadic hunter-gatherer communities to settled agriculture in the neolithic revolution, the effects of colonial expansion and settlements, and the environmental and human consequences of the industrial and technological revolutions.

Finally, environmental historians study how people think about nature - the way attitudes, beliefs and values influence interaction with nature, especially in the form of myths, religion and science.