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Saturday, 3 August 2013

5 EXTREME LIFE-FORMS THAT LIVE ON THE EDGE


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5 Extreme Life-Forms That Live on the Edge
By Liz Langley,
National Geographic, 2 August 2013.

We humans think we’re pretty hot stuff - but that depends on what you’re measuring. When it comes to enduring harsh conditions, for example, there are creatures in this world that make us look like a bunch of cupcakes.

Meet the extremophiles, so-called because they can withstand environments so intensely hot, cold, salty, acidic, alkaline, pressurized, dry, radioactive, or barren they’d put us out like a match in a hurricane. So impressive are their superpowers that NASA made them trading cards, just like Superman.

Extremophiles not only do exceptional things, they’ve opened our minds about what life is and what kind of environments can support it, widening our view of the potential for life on other planets, scientists say.

“People who work with extremophiles have pretty much the same needs as people who are going to Mars except they can usually be there to operate the instruments themselves; they don’t have to have a robot do it. But it terms of technology and techniques it’s really the same,” said Jay Nadeau, associate professor of biomedical engineering at McGill University who studies extremophilic bacteria in the Canadian Arctic.

Her team was the first to describe the microbe genus Thiomicrospira, which has slight modifications to its cell structure that allow it thrive in its icy home.

Extremophiles could also help us with more earthly concerns, from pharmaceuticals to producing energy, but, Nadeau said, “A lot of this work is really done just for the interest in finding out what there is on planet Earth that we don’t know about…and there’s a lot of that.”

Bonus: Some of them are just plum adorable. Here are five of the coolest extremophiles.

1. Tardigrades and Tiaras

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It may look like a bear, but it’s actually a millimetre long.

No question - if there were a cute extremophile contest, the tardigrade (above) would win. They even have a cute a nickname - “water bear” - and look like manatees dressed in spacesuits for Halloween.

Measuring about a millimetre long, the tardigrade is a polyextremophile, which means its capable of surviving numerous harsh conditions. Sarah Bordenstein of the Marine Biological Laboratory at Woods Hole writes that they can withstand temperatures from -328 °F (200 °C) up to 304 °F (151 °C), lack of water and oxygen, “boiling alcohol,” (who thought of that?) and a thousand times the radiation we can take.

One way they survive is by going into cryptobiosis, a state of suspended animation, in which body functions like metabolism temporarily shut down. They’ll stay in this shrunken state - in which they’re called a “tun” - until conditions improve. They have been known to do this for decades.


No, we don’t have a number for their agent.

2. Brine Shrimp: Salty Survivors

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A brine shrimp up close.

Those of us who could eat popcorn, chips, and salty snacks until we pop can easily identify with the halophile, a creature that thrives in very salty environments. The Great Salt Lake brine shrimp are halophiles that are at home in places like the Great Salt Lake of Utah, parts of which are ten times saltier than the ocean.

Brine shrimp are such super salty survivors because, according to the Great Salt Lake Ecosystem Program,  their outer body is impermeable to water so the salt water only enters through the mouth. Two pumps, the shrimp’s gills and a special neck gland, filter the salt out and help keep a salt balance in the body.

They also have three types of haemoglobin, a protein that binds oxygen in the blood. Haemoglobin levels increase in the shrimp when the water’s salinity increases.

3. Methane Ice Worm

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No, it’s not an alien - it’s a methane ice worm.

They may look alien, but the hideous creature pictured above is a methane ice worm, discovered here on Earth in 1997, living on the sea floor of the Gulf of Mexico. These extremophilic flat, pinkish, up-to-two-inch-long worms were found burrowing into mounds of methane and likely living on the bacteria that grow on the methane.

In fairness if you looked like that you’d burrow, too.

Considerably less ghastly are glacial ice worms, squiggly black creatures a few centimetres long. Daniel Shain, biology department chair at Rutgers-Camden, has sought out ice worms in far flung places places from Tibet to Alaska - partly funded by National Geographic. (Watch a video of the ice worms in Alaska.)

Reporting on a hike lead by Shain, Doug O’Harr of the Anchorage Daily News reported seeing so many worms that one glacier appeared to have “sprouted sparse hair.”

Glacial ice worms are “the largest animal known to complete its life cycle on glacier ice, which is quite a feat,” Dan wrote in an email.

They survive on algae and are similar to earth worms but their body functions - reproduction, metabolism, growth - all occur at the freezing mark, at about 32° Fahrenheit (0° Celsius). If temperatures go up a few degrees, though, to about 40° Fahrenheit (4° Celsius), the worms can’t take it - they eventually melt and die.

Which shows that our idea of “extreme” is relative.

4. “Rushing Fireball” Microbe

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Pyrococcus furiosus (image source)

In some images,  Pyrococcus furiosus looks like an abstract drawing of a Fantasia goldfish, in others like butterscotch candy left in the dish a little too long. In real life this tough little anaerobe, whose name means “rushing fireball,” prefers water temperatures at the boiling point: 212° Fahrenheit (1000° Celsius), which makes it a hyperthermophile. Thermophiles like it hot; hyperthermophiles would pick hell for vacation.

Karl Stetter discovered P. furiosus in the geothermally heated marine sediments in Italy’s Vulcano Islands in the 1980s. (See more pictures of marine microbes.)

Russell McLendon of Mother Earth News reported this spring that scientists at the University of Georgia have been diddling around in the fireball’s genes, creating a version of the microbe that prefers cooler climates and has a taste for carbon dioxide rather than its usual carbs. The hope is to create a variant of the fireball that breathes in carbon dioxide and turns it into fuel.

When that’s done we’d like a cat that breathes in anger and turns it into donuts. Science? Anyone?

5. Radiation-Resistant Bacteria

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Deinococcus radiodurans (image source)

Beautiful, resilient, mysterious…all the qualities of a film noir heroine locked are wrapped in this bacteria Dienococcus radiodurans, which looks - at least in this image - like a changing mood ring.

The Genome News Network says it was discovered “nearly fifty years ago in a can of ground meat that spoiled despite having been sterilized by radiation,” and that resistance to radiation is the prize-winning talent of this polyextremophile. When its genome is broken down by radiation, D. radiodurans just stitches it back together perfectly - and pretty quickly - and keeps going.

The Lazurus microbe, as it’s been called, holds the Guinness World Records title for “Most Radiation Resistant Life-Form“ - it can withstand about 3,000 times as much radiation as we can. And it’s a one-celled organism.

This makes it of great interest to scientists: Figuring out how the microbes resist radiation may give insight into protecting people from various types of radiation exposure, from chemotherapy to sun damage.

So…what did you do today?

Top image: Tardigrade (source)

[Source: National Geographic. Edited. Some images added.]



Friday, 2 August 2013

10 UNSOLVED RANSOM KIDNAPPINGS


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10 Unsolved Ransom Kidnappings
By Robin Warder,
Listverse, 2 August 2013.

One of the most infamous crimes of all time took place in 1932 when Charles Augustus Lindbergh Jr., the 20-month-old son of the renowned aviator, was kidnapped for ransom. Even after a ransom was paid, the infant wasn’t returned, and his body was found near the Lindbergh home two months later. Even though a suspect was captured and executed, the case remains surrounded in controversy to this day.

Unfortunately, other notorious ransom kidnappings didn’t have happy endings either. In some cases, the victim was murdered or never found. In others, a likely perpetrator was caught and punished for the crime, but they refused to reveal what happened to the victim.

10. Charley Ross

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One of the first known victims to receive widespread publicity after being kidnapped was a four-year-old boy named Charley Ross. On July 1, 1874, Charley was playing with his older brother in the front yard when two men pulled up in a horse-drawn carriage and offered the boys candy and fireworks if they would take a ride with them. The boys were taken into town and after Walter was given money to go inside a store and buy fireworks, the two men left with Charley.

Charley’s seemingly wealthy father, Christian Ross, received notes demanding a US$20,000 ransom for his son. However, a stock market crash had left Christian in debt, and he could not afford to pay, so he went to the authorities for help. Even though the kidnappers provided instructions for where to deliver the ransom, they never showed up. Months later, two criminals named Bill Mosher and Joe Douglas were shot while attempting to burglarize a house. Mosher was killed instantly, but before dying, Douglas confessed that the two of them were responsible for the Charley Ross abduction. Charley’s brother positively identified them as the men from the carriage. Unfortunately, they took the secret of what actually happened to Charley to their graves.

9. Dorothy Ann Distelhurst

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The afternoon of September 19, 1934, five-year-old Dorothy Ann Distelhurst left her school to walk home, but never arrived. After the authorities were notified, they spent the next several days searching for her, but could find no trace. However, once the national media began focusing on the case, the Distelhurst family started to receive ransom letters. Authorities were unsure if any of them were genuine or if they were inspired by the publicity.

The most vivid ransom demand stated that Dorothy Ann would have her eyes burned out with acid if her family did not pay US$175,000. On November 13, two employees of the Davidson County Tuberculosis Hospital were digging flower beds in a remote corner and wound up uncovering Dorothy Ann’s body. Her skull had been crushed, and her personal items and clothing were discovered some distance away. Most disturbingly, her face had been burned away with acid. In spite of an intensive investigation, the murderer was never found, and the case remains unsolved.

8. Douglas Mueller

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At approximately 9:30 PM on March 16, 1977, 19-year-old Douglas Mueller finished his shift at a gas station in Scottsdale, Arizona and left to drive home. He never arrived, and his parents soon notified police. The next day, Douglas’s parents received an anonymous phone call ordering them to go to a specific payphone for instructions. Douglas’s father went to this payphone and found his son’s driver’s license, along with a ransom note that appeared to be in Douglas’s handwriting.

The note demanded that the Muellers pay US$57,000 for Douglas’s safe return and provided instructions for a drop-off. The Muellers followed these instructions and dropped the money at the specified location, but no one ever showed up. Throughout the next two months, the Muellers received three more calls and went through three more drops, but the ransom was never claimed. Douglas’s abandoned car was later discovered at an airport, but his family would not receive any answers until 2011. After a hiker came across a male femur bone in a remote desert area, DNA testing would confirm that it belonged to Douglas. However, the rest of his remains have yet to be found, and the identity of his murderer is still unknown.

7. Annie Laurie Hearin

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On July 26, 1988, 73-year-old Annie Laurie Hearin vanished from her residence in Jackson, Mississippi. Annie’s husband, Robert Hearin, was a prominent and successful businessman, and the family’s estate was worth from US$100–200 million. When Robert came home, he discovered blood smears and a ransom note. The note instructed him to pay money to franchises owned by School Pictures, a company Robert had taken over a few years earlier. In exchange for the return of his wife, Robert would disburse the ransom money to 12 School Pictures locations throughout America.

When Robert held a press conference begging for Annie’s return, he received another note, which was signed by her and stated she would be sealed in a cellar if he did not comply with the demands. Robert mailed the money to the franchises listed, and one of these recipients was an attorney named Newton Alfred Winn. Winn had once been in a lawsuit with Robert over unpaid money, so authorities believed he was responsible for the kidnapping. In 1990, Winn was arrested and sentenced to 19 years in prison for conspiracy to kidnap, extortion, and perjury. He always maintained his innocence and was released in 2006. Unfortunately, Annie was never found.

6. Clark Toshiro Handa

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During the evening of August 23, 1984, a three-year-old boy named Clark Toshiro Handa was abducted from his bedroom in Fairfield, California. The family had nine children, and Toshiro shared the bedroom with five other siblings, but none of them could recall anyone entering the room during the night. The next morning, Toshiro’s mother found a note on his bunk bed and noticed that the adjacent window was open. The note demanded that the Handas pay a ransom in exchange for Toshiro’s return.

Toshiro’s family complied with the instructions and brought money to a specified rendezvous point, but no one showed up (we’re noticing a trend here). The Handas never heard from Toshiro’s kidnapper again. Unfortunately, it was nearly a week before missing posters were circulated, and the abduction received some media coverage, so there were never any strong leads about who was responsible. The ransom demand was particularly bizarre - Toshiro’s family was not known for having a lot of money, so the reason he was targeted is unknown.

5. June Robles

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Six-year-old June Robles was the daughter of Fernando Robles, owner of the Robles Electric Company. Her family was one of the wealthiest in Tucson, Arizona. On April 25, 1934, June was leaving Roskruge School when she was abducted. Two hours later, Fernando Robles was handed a note by a boy who had been paid 25 cents to deliver it. The note was signed by someone identifying themselves as “Z” and demanded that Fernando pay a US$15,000 ransom for the return of his daughter.

After police were notified, June’s grandfather received a second note from the kidnapper, who agreed to lower the ransom to US$10,000. Fernando was given specific instructions about where to deliver the money, but when he attempted to do so, no one showed up (surprise). On May 14, the governor received an anonymous postcard that revealed June’s location. She was found inside a metal box - buried in the desert outside Tucson. Even though June had been chained in the box for 19 days, the kidnappers provided constant food and water, so she was still alive. There were a lot of potential suspects, but not enough evidence to convict anyone. A federal grand jury reviewed the case, referring to it as an “alleged kidnapping” and implying that the Robles family might have staged the whole thing as a hoax.

4. Robert Wiles

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Robert Wiles was the 26-year-old son of Tom Wiles, the millionaire owner of the aircraft service company, National Flight Services. Robert was employed with the company and worked at Lakeland-Linder Regional Airport in Florida. On April 1, 2008, Robert disappeared from work. Two days later, his parents were e-mailed a ransom note from “Group X,” demanding US$750,000 for Robert’s safe return. Tom followed the instructions and left the money, but no one collected it, and he never heard from “Group X” again.

Suspiciously, Tom had previously purchased kidnapping insurance from his company for the exact amount of US$750,000. This led to speculation that an employee of National Flight Services might have been responsible. The investigation eventually turned to the operations manager at Lakeland, who was reportedly the last person to see Robert alive. It was discovered that on the evening of Robert’s disappearance, Holt had purchased plastic sheeting and two rolls of duct tape. Holt’s alibi did not hold up, and he also allegedly used Robert’s cell phone to send the ransom e-mail. In January 2012, Holt was convicted of manslaughter and sentenced to 30 years in prison.

3. Georgia Jean Weckler

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On May 1, 1947, eight-year-old Georgia Jean Weckler was driven home from school by a neighbour and dropped off at the end of the driveway at her rural home. Georgia never arrived home and was not seen again. Around the time of Georgia’s disappearance, a Ford sedan was seen in the same area, and witnesses in Fort Atkinson would later see a girl matching Georgia’s description, struggling with a man inside the vehicle.

Since Georgia’s father was a fairly wealthy public official, it was speculated that she may have been kidnapped for ransom, but no demands were ever made. Months later, a recently convicted rapist and murderer named Buford Sennett confessed that he and an unidentified accomplice had kidnapped Georgia for ransom. They gave her sleeping pills, but it was accidentally too much and she died, so they tossed her into the Blue River. A witness actually reported seeing Sennett burn Georgia’s body, and some ashes were later found on his property, but forensic testing on them proved inconclusive. Sennett later recanted his confession, but whether or not his kidnapping story was true, Georgia Jean Weckler is still missing.

2. Daniel Goldman

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In 1966, Daniel Goldman was the 17-year-old son of Aaron Goldman, a wealthy and prominent contractor. In the early morning of March 28, an unidentified man entered the Goldman home and demanded that Aaron and his wife pay him US$10,000 in cash. The Goldmans said they didn’t have that much money in the house, so the assailant tied them up. He threatened to kill their son if they didn’t pay him a US$25,000 ransom and said he would call them to provide instructions. He then abducted Daniel and fled the scene in Daniel’s car, which was found hours later. The abductor never contacted the Goldmans again.

One theory was that the kidnapping was orchestrated by career criminal Joe “Chicken” Cacciatore, who resembled the family’s description of the kidnapper. It was rumoured that the Goldmans stashed US$10,000 in their home so they could help Daniel leave the country and avoid the draft when he turned 18. Cacciatore reportedly heard this rumour and Daniel was one day shy of his 18th birthday when he was kidnapped. In 1986, a woman claiming to be Daniel’s former girlfriend told a bartender that Daniel was killed after recognizing one of his kidnappers, but she disappeared after police were contacted.

1. Virginia Piper

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On July 27, 1972, wealthy investment banker Harry C. Piper Jr. returned to his home to discover his housekeeper taped to a chair. She told him that his wife, Virginia, had been abducted by two masked men who left behind a ransom note. In exchange for Virginia’s safe return, they demanded US$1 million, which was the largest ransom in United States history. Harry’s instructions were to drop the US$1 million behind a Minneapolis bar, and he complied. The next day, an anonymous tip revealed that Virginia was chained to a tree in Jay Cooke State Park, and she was soon found alive.

Over the years, only US$4,000 of the ransom was recovered. In 1977, Kenneth Carnahan and Donald Larson were charged with the kidnapping. After they were convicted, the two men were granted a retrial. It was ruled that the judge had inappropriately barred the testimony of a defense witness, who claimed she had overheard some other suspects plot the kidnapping. During the retrial, an expert witness testified that the evidence had been tampered with by the FBI, so Carnahan and Larson were acquitted.

[Source: Listverse. Edited.]


10 BIGGEST DESERTS ON EARTH


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The 10 Biggest Deserts On Earth
By Elizabeth Howell,
Live Science,1 August 2013.

Big deserts

Earth is a planet covered with habitable areas, but some of those locations are a little more hostile to life than others. In deserts, which generally are defined as areas that receive less than 10 inches (254 millimetres) of rain or snow annually, the plants and animals must subsist on this meagre precipitation.

The world's 10 biggest deserts are found on just about every continent, many of them forming in the shadow of immense mountain ranges that block moisture from nearby oceans or bodies of water. They're often the site of unusual rock formations and, in some cases, amazing archaeological finds.

10. Chihuahuan Desert

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175,000 square miles (282,000 square km)

Straddling the U.S.-Mexico border, the Chihuahuan Desert is bigger than the state of California, according to New Mexico State University. Parts of it are in the states of Texas, New Mexico and Arizona. Less than 9 inches (228 mm) of rainfall falls on average every year, according to the Chihuahuan Desert Education Coalition.

As with many other deserts worldwide, the Chihuahuan Desert formed in the rain shadow of both the Sierre Madre Occidental (on the west) and the Sierra Madre Oriental (on the east), which both stop water from the Pacific Ocean and the Gulf of Mexico from getting inland.

Underneath the desert and New Mexico's Guadalupe Mountains lies more than 300 caves. Those in at least one of those regions, Carlsbad Caverns National Park, were created after sulphuric acid penetrated the surrounding limestone.

9. Great Basin Desert

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190,000 square miles (492,000 square km)

Unlike every other desert in the United States, the Great Basin is a "cold" desert - one where most of the precipitation falls as snow. Its geographic extent includes most of Nevada, part of Utah and parts of many surrounding states. Rainfall in the region ranges between 6 and 12 inches (150 and 300 mm) annually.

The desert came to be because it was in the rain shadow of the Sierra Nevada Mountains of eastern California, according to the National Park Service. The desert, in turn, also affects surrounding areas. Strong winds known as the Santa Ana often blow into Southern California after forming in areas of high pressure in the Great Basin.

The Great Basin is also home to some unusual rocks, such as some found in central Nevada in 2009 that were described as dripping like honey. The deformation is taking place due to changes in the Earth's mantle, which alters due to intense pressure and heat within Earth's surface. Heavier material in the lithosphere, as it warms up, sinks through the lighter mantle, trailing material after it.

8. Syrian Desert

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200,000 square miles (518,000 square km)

The Syrian Desert is described as an "arid wasteland" by Merriam-Webster. Covering much of Iraq, Jordan, Saudi Arabia and Syria, the region is marked by lava flows and was an "impenetrable barrier" to humans until recent decades. Now, highways and oil pipelines cross the region, which receives less than 5 inches (125 mm) of rain annually, on average.

Humans were able to reach parts of it in ancient times, though. One area, now dubbed "Syria's Stonehenge," was discovered in 2009. It includes stone circles and possibly, tombs, according to a 2012 Discovery News report.

The Es Safa volcano field near Damascus is Arabia's largest volcanic field. The vents found in that area were active about 12,000 years ago, during the Holocene Epoch. More recently, a boiling lava lake was spotted in the region around 1850.

7. Great Victoria Desert

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250,000 square miles (647,000 square km)

The Great Victoria Desert covers a great deal of Australia and is mostly made up of parallel dunes as well as some salt lakes, according to an atlas from the Government of South Australia. The dunes are mostly red sand that came from the Western Australian Shield, changing to white as one moves south due to sands coming from the coast.

The Australian government describes the region as one with "variable and unpredictable rainfall." Averaging out data between 1890 and 2005, rainfall is about 6.4 inches (162 mm) annually. Due to the harsh environment, most of the desert is split between Aboriginal lands, conservation areas and crown land, with no major cities.

One of the Outback's greatest ecological threats comes from camels, whose ancestors were imported from India, Afghanistan and Arabia during the 19th century for work in the desert. A 2013 BBC report said the approximately 750,000 feral camels drink an ordinate amount of water and also damage infrastructure. "Camels are almost uniquely brilliant at surviving the conditions in the Outback," said explorer Simon Reeve in the report. "Introducing them was short-term genius and long-term disaster."

6. Patagonian Desert

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260,000 square miles (673,000 square km)

The Patagonian Desert is a large desert lying across much of Argentina. The desert and semi-desert area stretches from the Atlantic Ocean to the Andes, with mostly treeless plains, according to the Encyclopaedia Britannica.

Like California's Death Valley, the Patagonian Desert lies in the "rain shadow" of a high mountain range - in Patagonia's case, the Andes. Some regions of the desert receive as little as 6 to 8 inches (160 to 200 mm) of rainfall a year, according to Dryland Climatology, a 2011 book by Florida State University meteorologist Sharon E. Nicholson.

"When air masses are forced over mountains and downslope, they warm and their capacity for holding water vapour increases," wrote Susan Woodward, an emeritus geography professor at Virginia's Radford University, on a website about deserts. On the leeward side of a mountain, she added, evaporation happens faster than rainfall, creating an arid environment.

5. Kalahari Desert

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360,000 square miles (930,000 square km)

The Kalahari Desert covers large tracts of South Africa, Botswana and Namibia. It averages less than 20 inches (500 mm) of rain a year in, but some locations receive less than 8 inches (200 mm) annually, according to the 1991 book The Kalahari Environment by David G. Thomas and Paul A. Shaw.

Described as "featureless" by the Encyclopaedia Britannica, the Kalahari is mostly covered by sand sheets that were formed sometime between 2.6 million and 11,700 years ago, probably due to the action of wind and rain. The sheets have been virtually unchanged since then.

The Kalahari was also a site of human activity thousands of years ago. In one excavated area, South Africa's Wonderwerk Cave, archaeologists found evidence of fires lit about one million years ago. A separate discovery of artefacts in Botswana's Tsodilo Hills implied humans performed rituals 70,000 years ago.

4. Gobi Desert

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800,000 square miles (1.3 million square km)

Encompassing large regions of China and Mongolia, the Gobi Desert is arid in parts and more "monsoon-like" in others, meaning it sees wet and dry seasons, according to the Encyclopaedia Britannica. Rainfall varies from about 2 to 8 inches a year (50 mm to 200 mm), depending on the location. The eastern region in particular gets a lot of rainfall in the summer, similar to how monsoons operate in wetter regions.

In 2011, strange zigzag patterns in the Gobi emerged in Google's pictures, prompting a range of conspiracy theories that even included aliens. But the lines were most likely used to calibrate Chinese spy satellites to help the spacecraft orient themselves in orbit, said Jonathon Hill, a research technician and mission planner at the Mars Space Flight Facility at Arizona State University.

The Gobi is also a good spot for dinosaur-hunting. A rare Tyrannosaurus Rex skeleton uncovered in that region was auctioned off in 2012, fetching US$1 million amid a legal dispute.

3. Arabian Desert

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900,000 square miles (2.3 million square km)

The Arabian Desert encompasses Saudi Arabia and surrounding countries such as Oman and parts of Iraq. How dry and hot the desert is depends on where you're standing. The interior of the desert can get to a scorching, dry 129 F (54 C). Areas on the coast and in the highlands, however, have more humidity and can also have fog and dew during the cooler parts of the day, according to the Encyclopaedia Britannica.

On average, annual rainfall is less than 4 inches (100 mm), but depending on the region it can range anywhere from 0 to 20 inches (0 to 500 mm). But human activity has artificially irrigated and greened parts of the desert.

Crop circles exploded in abundance in Saudi Arabia during the past three decades, according to a series of Landsat images. These are possible because engineers drilled into a "fossil" water acquifer that is more than 20,000 years old, according to NASA. It has been estimated that at current rates of usage, the water will go dry in 50 years.

2. Sahara

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3.3 million square miles (8.6 million square km)

The Sahara is notable not only for its vast size, but parching lack of rainfall. Annual precipitation in the world's second-largest desert is less than 0.9 inches (25 mm) every year. On the east side of the desert, according to NASA, rainfall could be as low as 0.2 inches (5 mm) annually.

While water doesn't often fall to the ground, it's common for water droplets to hover above the desert as fog. There isn't much vegetation in the Sahara to hold on to heat after the sun goes down, so the temperatures can actually get quite cold at night. The sudden shift between day and night temperatures can bring about the fog.

The desert also features a high volcano, Emi Koussi, which is in Chad at the southeastern end of the Tibesti Range. Standing 11,204 feet (3,415 meters) above sea level, there are lava flows and other volcanic features that appear to be as young as two million years old. There is also an active thermal region on the volcano's south flank.

1. Antarctica

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5.5 million square miles (14.2 million square km)

Nestled around the South Pole, where the coldest temperature on Earth was recorded and which doesn't receive sunlight for months every year, it's sometimes hard to think of icy Antarctica as a desert. But it is the world's largest one because very little precipitation falls there - on average, it gets less than 2 inches (50 millimetres) a year, mostly as snow.

Despite the low snowfall, vast glaciers cover 99 percent of Antarctica's surface. That's because the average temperature (minus 54 degrees Fahrenheit, or minus 48 degrees Celsius) slows down evaporation to a crawl. Over long periods of time, the snowfall accumulates at a rate faster than Antarctica's ablation, according to "Discovering Antarctica," a project of the U.K.'s Royal Geographical Society.

Parts of Antarctica are showing strong signs of warming up along with global climate change, however. Temperatures in the Antarctic Peninsula have increased by 4.5 degrees Fahrenheit (2.5 degrees Celsius) over the past 50 years - five times the rate of the rest of the planet. And scientists think that warm ocean waters could be melting Antarctica's glaciers as they flow under the floating tongues of ice.

[Source: Live Science. Edited.]


12 HOTTEST GADGETS IN AUGUST 2013


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The Goods: August 2013's Hottest Gadgets
By Amber Williams,
Popular Science, 1 August 2013.

A spoiler-blocking web extension, Nerf's farthest-firing gun, and more.

1. Silencer

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The Chrome extension Silencer blocks spoilers from social networks by filtering out posts with words that could ruin a TV episode or sporting event. A user enters a keyword or chooses a list; for example, the Arrested Development list weeds out 38 trigger words. Price: Free.

2. Hospitality Umbrellas Rainshader

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The Rainshader is the toughest umbrella on the market. Because its 10 fiberglass ribs extend below a user’s shoulders, the helmet-shaped umbrella is less likely to invert. In wind-tunnel tests, it withstood gusts up to 38 mph without blowing inside out. Price: US$33.

3. Arduino Robot

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Meet Arduino’s first pre-assembled robot. The 7-by-4-inch wheeled robot has two microprocessors - one for the motor and one for the sensors - an LCD screen, a digital compass, and a handful of other inputs. Price: US$265.

4. Hasbro Nerf N-Strike Elite Centurion

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With a 100-foot range, the Centurion shoots farther than any other Nerf gun. To boost distance, engineers added a massive spring. They also designed a heftier dart with twice the circumference of a standard one so it gains more momentum and carries farther. Price: US$50.

5. Nvidia GeForce GTX 780

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The GeForce GTX 780 graphics-processing unit records gameplay constantly, so a player has instant proof of his epic moves. With this feature, called ShadowPlay, the GPU’s encoder auto records the last 20 minutes of action, at 1080p and 30 frames per second. Price: US$650.

6. Milwaukee Tool Fastback II

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The Fastback II one-handed utility knife opens three times faster than two-handed versions. After a user pushes a release button on the handle, the carbon-and-steel blade swings into place with a flip of the wrist. Price: US$17.

7. Devotec Industries Fuel Micro Charger

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The Fuel Micro Charger is the smallest backup cell phone battery yet. The lithium-ion battery connects via micro-USB to a phone, providing about 25 minutes of extra talk time. Engineers used flexible printed circuit boards to fit all the components in the 1.3-by-0.9-inch aluminium housing. Price: US$25.

8. Big Ass Fans Haiku LED

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The blades, motor, and lights are all integrated into the body of the Haiku LED ceiling fan, making it the thinnest one available, at just 2.6 inches thick. Air foils on the motor help direct heat away from the electronics, which control the 18 dimmable LEDs. Price: US$920.

9. Kreg Tool Automaxx Bench Klamp 3" Reach

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The Automaxx bench clamp automatically adjusts to the thickness of a piece of wood. Instead of turning a knob to hold down a two-by-four, a user just closes the clamp. When a bar within the handle slides down to the cam lock, the bar and lock engage, keeping everything steady. Price: US$31.

10. Vertus Audio Vertus

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With a pair of Vertus receivers, a user can stream music to two speakers in different rooms. The Bluetooth-enabled dongles plug into any speakers with a 3.5mm connector. Then they pair with an audio source as well as each other. They have a 30-foot range for makeshift stereo systems or indoor-outdoor parties. Price: US$89.

11. Brookstone Fogless Shower Mirror

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The Brookstone shower mirror won’t fog up no matter how steamy the bathroom gets. A user fills the cup above the 12-by-9-inch stainless-steel mirror with water. The water trickles down behind the metal, bringing it to the temperature of the shower and preventing condensation. Price: US$60.

12. Giro Air Attack

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The Air Attack helmet significantly reduces drag. After wind tunnel tests, Giro engineers found that the tapered tail on a helmet doesn’t aid aerodynamics in many situations. So they nixed it. For cooling, a suspension system holds the shell three millimetres above the head; as a result, air flows under the helmet at the forehead. Price: US$240.

Top image: Giro Air Attack. Screen captured from Giro/YouTube.

[Source: Popular Science. Edited. Top image added.]