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Friday, February 29, 2008
Naval warships might look like all-powerful vessels but they are also highly vulnerable to being spotted by the enemy. That fear of being detected has led the military to develop new stealth technologies that allow ships to be virtually invisible to the human eye, to dodge roaming radars, put heat-seeking missiles off the scent, disguise their own sound vibrations and even reduce the way they distort the Earth’s magnetic field, as senior lecture in remote sensing and sensors technology at Britannia Royal Navy College, Chris Lavers, explains in March’s Physics World.
Wars throughout the twentieth century prompted advances in stealth technologies. Some of the earliest but most significant strides towards invisibility involved covering ships with flamboyant cubist patterns – a technique known as “dazzle painting”. During the Second World War, the US military even worked out a way of using lights to make the brightness of a ship match that of the background sea.
When British physicist Robert Watson Watt was charged with designing a ‘death ray’ to destroy entire towns and cities during the Second World War, he calculated it impossible. He did conclude however that radio waves could be used to detect ships and aircrafts too far way to be seen by the naked eye.
Radar was born. For ships to dodge radar, both a ship’s geometry and a ship’s coating have to be considered. Radars are particularly receptive to right angles, which is why modern battleships are often peculiarly shaped. Special paint and foam-coating have also been used to cover ships, which convert radio-waves into heat and stop radio waves being reflected, rendering the signals useless.
The “stealthiest” ship that currently exists is Sweden’s Visby Corvette. Apart from being painted in grey dazzle camouflage and made of low-radar reflectivity materials, it also does not use propellers, which are the noisiest part of a ship. The vessel also has the lowest “magnetic signature” of any current warship.
But the next generation of warships could be truly invisible by exploiting “metamaterials” – artificially engineered structures first dreamt up by physicist John Pendry at Imperial College, London. Metamaterials are tailored to have specific electromagnetic properties not found in nature. In particular, they can bend light around an object, making it appear to an observer as though the waves have passed through empty space.
About the research, Chris Lavers writes, “If optical and radar metamaterials could be developed, they might provide a way to make a ship invisible to both human observers and radar systems, although the challenges of building a cloak big enough to hide an entire ship are huge.”
On the net: http://physicsworld.com
Source: Institute of Physics
Vecna Technologies
The Bear is highly manoeuvrable
The US military is developing a robot with a teddy bear-style head to help carry injured soldiers away from the battlefield.
The Battlefield Extraction Assist Robot (BEAR) can scoop up even the heaviest of casualties and transport them over long distances over rough terrain.
New Scientist magazine reports that the "friendly appearance" of the robot is designed to put the wounded at ease.
It is expected to be ready for testing within five years.
While it is important to get medical attention for injured soldiers as soon as possible, it is often difficult and dangerous for their comrades to reach them and carry them back.
The 6ft tall Bear can cross bumpy ground without toppling thanks to a combination of gyroscopes and computer controlled motors to maintain balance.
BEAR FACTS
Robot carries dummy - annotated with details
1. Teddy bear face designed to be reassuring
2. Hydraulic upper body carries up to 227kgs (500lbs)
3. When kneeling tracked "legs" travel over rubble. Switches to wheels on smooth surfaces
4. Dynamic Balance Behaviour (DBB) technology allows the robot to stand and carry loads upright on its ankles, knees or hips for nearly an hour
It is also narrow enough to squeeze through doorways, but can lift 135kg with its hydraulic arms in a single smooth movement, to avoid causing pain to wounded soldiers.
While the existing prototype slides its arms under its burden like a forklift, future versions will be fitted with manoeuvrable hands to gently scoop up casualties.
The Bear is controlled remotely and has cameras and microphones through which an operator sees and hears.
It can even tackle stairs while carrying a human-sized dummy.
Daniel Theobald, the president of Vecna Technologies, which is developing the robot for the US Army, said: "We saw a need for a robot that can essentially go where a human can. The robot will be an integral part of a military team."
Gary Gilbert, from the US Army's Telemedicine and Advanced Technology Research Centre in Frederick, Maryland, said that the teddy bear appearance was deliberate.
"A really important thing when you're dealing with casualties is trying to maintain that human touch."
Vecna is working on other potential applications for the robot technology - including helping move heavy patients in hospital.
A controversial theory, that strange red rains in India six years ago might have contained microbes from outer space, hasn’t died.
In fact, things might be getting even weirder.
A new study suggests the claimed connection between scarlet rain and tiny celestial visitors may be consistent with historical accounts linking colored rain to meteor passings. These would seem to echo the India case, in which organisms are proposed to have fallen out of a breaking meteor.
Yet the historical analysis, he concluded, shows the question is “much more complex than one might have expected” and “should be investigated with every scientific resource” available.
The study, by doctoral student Patrick McCafferty of Queen’s University Belfast, is published in the advance online edition of the International Journal of Astrobiology.
McCafferty analyzed, as he wrote, “80 accounts of red rain, another 20 references to lakes and rivers turning blood-red, and 68 examples of other phenomena such as colored rain, black rain, milk, bricks, or honey falling from the sky.”
Sixty of these events, or 36 percent, “were linked to meteoritic or cometary activity,” he went on. But not always strongly. Sometimes, “the fall of red rain seems to have occurred after an airburst,” as from a meteor exploding in air; other times the odd rainfall “is merely recorded in the same year as a stone-fall or the appearance of a comet.”
The phenomena were recorded in times and places as varied as Classical Rome, medieval Ireland, Norman Britain and 19th century California, noted McCafferty, who has a master’s degree in archaeology and studies Irish myth and astronomy. McCafferty added that tales suggestive of red rain-meteor links also crop up in myth.
With witnesses to past events all long dead, McCafferty wrote that probably no historical analysis will ever settle the debate over the 2001 rainfalls in India.
Research claiming to connect these rains to extraterrestrial life provoked disbelief when they were first reported widely, in World Science. “I really, really don’t think they are from a meteor!” wrote Harvard University biologist Jack Szostak, referring to cell-like particles that had been reported to permeate the collected rainwater.
The curious events began on July 25, 2001, when residents of Kerala, a region in southwestern India, started seeing scarlet rain in some areas. It persisted on-and-off for some weeks, even two months. Scientists couldn’t identify the cell-like specks that gave the water its scarlet hue. Speculation of possible extraterrestrial origins began.
Two Indian scientists later published a chemical and biological analysis suggesting, they said, that the specks might indeed be little aliens. They “have much similarity with biological cells” but without DNA, wrote the researchers, Godfrey Louis and A. Santhosh Kumar of India’s Mahatma Gandhi University. “Are these cell-like particles a kind of alternate life from space?”
They cited newspaper reports that a meteor broke up in the atmosphere hours before the red rain. Louis and Kumar’s research paper appeared in the April 4, 2006 online edition of the research journal Astrophysics and Space Science. In previous, unpublished papers, the pair also claimed the particles could reproduce in extreme heat.
Some researchers, including Chandra Wickramasinghe, director of the Center for Astrobiology at Cardiff University, U.K., have said that Louis and Kumar’s idea may well be correct. He and other supporters pointed to the consistency of the alien-cell hypothesis with the popular “panspermia” theory, which holds that meteors and comets might have seeded life throughout many planets.
But other scientists have cited problems with the theory, including a lack of clear evidence for any meteor, and the knotty question of how micro-aliens might have stayed aloft for months after bursting out of a meteor.
“Without conclusive evidence such as meteoritic dust mixed with red rain, it is difficult to say anything specific about Kerala’s red rain,” McCafferty wrote. But in history, he added, “there appears to be a strong link between some reported events [like it] and meteoritic activity. The reported airburst just before the fall of red rain in Kerala fits a familiar pattern, and cannot be dismissed so easily as an unrelated coincidence.”
The sky is not an ethereal, sterile realm. It's teeming with bacteria, and scientists say that the microbes play a powerful role in producing rain and snow.
While the idea that bacteria could prompt precipitation was previously known, a paper published this week in Science shows that they're more important than anyone expected.
Researchers led by Louisiana State University microbiologist Brent Christner analyzed snow samples from around the world, categorizing the content of their "nucleators" -- tiny particles that help water vapor coalesce and freeze.
All snow and most rain begins as ice. Though water is widely thought to have a freezing point of zero degrees Celsius, it's not so simple in the clouds, where pristine vapors only bind to form ice crystals at exceedingly cold temperatures. Nucleators let crystallization happen in the less extreme conditions that prevail in much of Earth's troposphere.
Christner found bacteria, technically known as "biological ice nucleators," in an atmospheric context. High levels of bacteria were present in nearly every sample.
"Atmospheric scientists haven't previously recognized that these particles are so widely distributed," he said.
The findings raise the question of how climate change and human activities will affect bacterial balances in the sky. More immediately, they're a starting point for research on bacterial contributions to cloud formation and precipitation.
In its latest report, the International Panel on Climate Change said that the impact of feedback loops involving clouds on global weather patterns are the "largest source of uncertainty" in current predictions of climate change.
Christner's findings won't overturn the IPCC's fundamental conclusions -- a high probability of dramatically rising global temperatures -- but they should spur research that will help scientists predict the changes in greater detail, said Princeton University climate scientist Leo Donner, who was not involved in the study.
Donner agreed that climate scientists had not appreciated the ubiquity of precipitation-causing bacteria in the atmosphere.
"One of the real uncertainties in the climate system is how cloud particles are nucleated," he said. "Climate models need information on nucleators. This is especially relevant for understanding how clouds change as atmospheric composition changes."
The fact that bacteria could cause snow and rain was discovered almost by accident in the 1970s by study co-author David Sands, a Montana State University plant pathologist, during his research on Pseudomonas syringae, a microbe that causes ice to form on leaves.
Unable to discover the source of repeatedly infected fields, Sands exasperatedly took to the skies. He did the scientific equivalent of dragging a cup through the clouds -- and lo and behold, there was P. syringae.
P. syringae is not the only biological ice nucleator, but it is the most common, and all varieties share a protein structure that provides a scaffold for free-floating water molecules. Once bound to the bacteria and to each other, the water vapors are able to freeze, and eventually fall back to Earth.
In a pure state, water vapors freeze at temperatures below -35 degrees Celsius. Nucleators allow this to happen in warmer conditions, and Christner's study found that bacteria are the most common warm-temperature nucleators of all.
Researchers never realized bacteria could be so widespread in the clouds, said Christner, because the technologies used to measure fine dust -- traditionally seen as the most important nucleator -- ignore microbe-sized particles.
"It's not that these atmospheric scientists are idiots -- they're not," he said. "But biological nucleators were not previously recognized as being that abundant or important. They're going to have to revise that."
Saturday, February 23, 2008
It has been so long since I last posted that I've almost forgotten how. Valentine's Day and its aftermath have kept me busy, then the indescribable sickness that comes from having fibromyalgia stole most of this last week away from me, keeping me bedridden and much of the time in a deep sleep ( asleep I don't hurt though!). I haven't managed really to get anything new posted on the site, much less make new jewelry (still working on custom orders, too).
The two bracelets here are composed primarily of amethysts, the February birthstone, and I've done something I don't usually do: I've used the same lampwork beads for both bracelets. These lampwork beads are very different from most borosilicate beads; they have different colours and a strange opal-like quality as well without really being opalescent. The colours led to the mixture that you can see in the bracelet above. Large faceted rondelles of pretty blue aquamarine mix well with the amethysts with the addition of the lampwork. And I do love box clasps with stones set in them.
The next amethyst bracelet uses the lampwork beads and dark and light amethysts in faceted nuggets and rounds for a more homogeneous look. Bali and Karen Hill Tribes sterling silver accent the two. They will both be on the Amethyst Bracelets page of the Cluny Grey Jewelry website.
I'm still rushing to catch up, so if you want some information about the amethyst gemstone, where it gets its name, etc. see last year's February post.
Meanwhile, everyone pray for Spring!
Thursday, February 7, 2008
I'm still working busily on Valentine's Day jewelry and am just taking a moment to post a few things in the last minutes. I have a Valentine's Jewelry page that I am trying to complete (yes, I'm just as last minute as many of those men who wait and wait to buy their gifts although you would be surprised at how many will get in touch with me a month ahead of time: I've been impressed!). 
The first picture is of a gold ankle bracelet made with rubies and goldfilled charms and beads. It's called "Turtle Days and Starfish Nights" after the little sea themed charms hanging from the tube beads. Next is a pair of earrings made with heart-shaped freshwater coin pearls (I call them "Baroque" because they have little extra tabs of nacre on them so while they are definitely a recognizable heart shape, they are a little "off", too). The earrings have Karen Hill Tribes butterfly beads and rest on a cabochon freshwater pearl that is bezel-set in sterling silver. They hang from sterling posts with a swirling design and another bezel-set pearl on the front. They would look great with the pearl and Swarovski crystal bracelet below created from the same freshwater pearl hearts and Azores (my favorite very pale blue) crystals. 
And of course, I have more red jewelry, a must for Valentine's Day jewelry since red symbolizes love and passion. The Swarovski crystal bracelet below features lampwork beads by Robin Weber, her fire opal beads that are a deep red laced with sterling silver for the ultimate in shine. I've mixed them with the darkest red Swarovski crystals, pretty Bali silver, and Karen Hill Tribes charms, including a garnet charm that hangs beside the heart-shaped Swarovski crystal in the middle of the bracelet. This bracelet can be found on the Swarovski Crystal Bracelets page as well as theValentine's Jewelry page. The bottom bracelet features red also, only a lighter tone this time. The sparkling silver-flecked lampwork beads are by Lynn Nurge of Laffinggull. These Swarovski beads are a lighter red tone to match with the lighter coloured lampwork beads, but they are still large (10mm) as are the ones in the bracelet before. This bracelet can also be found on the same pages. 
Back to work I go! And if you've been reading about all the terrible weather and the storms, yes, those were in my part of the country, the worst in Jackson, Tennessee were just across the Mississippi River from us (we're 3 miles away from the Missouri line to the north and to the east about 3 miles is the Mississippi River). The terrible storms were also just an hour south of us as well, but luckily we escaped harm although the winds here were strong enough to turn over our heavy metal patio chairs.
