Why Icicles Are Long And Thin

Mathematical Physics Explains

How Icicles Grow

When droplets of melted snow drip down an icicle, they release small amounts of heat as they freeze. Heated air travels upwards and helps slow down the growth of the icicle’s top, while the tip is growing rapidly. Knowledge of the mathematical equations that govern icicle growth — the same that apply to stalactites — could help in the prevention of icicle formation on power lines.


Icicles can be dangerous and deadly, yet they can create some of the most amazing winter scenes. And for scientists, those winter scenes are playgrounds for discovery.

It’s on those playgrounds that experts in physics and mathematics are building their theories on what it takes to create an icicle.

We all know icicles form when melting snow begins dripping down a surface. But what scientists didn’t know is how their shape is formed. What makes each icicle different?

University of Arizona Physicist Martin Short turned to mathematics to find out.

“Icicles have a certain mathematical shape, and this mathematical shape is universal among icicles,” Short tells DBIS.

So what is the math behind an icicle?

“Here I’ve drawn the profile of an icicle. Here is the height, and here’s the radius … Here’s the profile here, and I’ve written the formula here. The height is proportional to the radius to the four-thirds,” he says.

What does the formula have to do with an icicle’s shape? “It kind of looks like a carrot,” says Short. “It starts out flat and then sort of up as you go.”

As water drips onto an icicle and freezes, it releases heat. The warm air rises up the sides of the icicle. Short says that warm air layer acts like a blanket that’s an insulator, and so the blanket is very thin near the tip and thick at the top. That allows the top to grow very slowly and the tip to grow rapidly — creating a long, thin icicle.

It’s the same equation scientists use to study stalactites in caves, but instead of water, stalactites are formed by the buildup of calcium left after the water evaporates.

“If we know the mechanisms by which stalactites form, well, we could better preserve our natural caves that we have here, and try to stop them from eroding,” Short says.

And now that scientists know how icicles are made, it could lead to breakthroughs to prevent them from forming on power lines and trees.

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BACKGROUND: Researchers at the University of Arizona have found that the same mathematical formula used to describe the shape of stalactites that form in caves also describes the shape of icicles. This is surprising because the physical processes that form icicles are very different from those that form stalactites. Both have a unique underlying shape, resembling a kind of elongated carrot. This sheds light into the physics of how drips of icy water can swell into long, skinny spikes (icicles).

HOW THEY FORM: Stalactites are formations that hang from the ceilings of caves, formed when water erodes limestone and taking the calcium carbonate. As the water drips inside the cave and evaporates, it leaves behind the calcium, which forms a stalactite. The continued diffusion of carbon dioxide gas fuels the growth of a stalactite. In contrast, heat diffusion and a rising air column are keys to an icicle’s growth. Icicles form when melting snow begins dripping down from a surface such as the edge of a roof. There must be a constant layer of water flowing over the icicle in order for it to grow. The growth is caused by the diffusion of heat away fro the icicle by a thin fluid layer of water, and the resulting updraft of air traveling over the surface. That updraft occurs because the icicle is generally warmer than its surrounding environment, and thus convective heating causes the surrounding air to rise. As the rising air removes heat from the liquid layer, some of the water freezes, and the icicle grows thicker and elongates.

PUT TO THE TEST: To compare the predicted shape to real icicles, the researchers compared pictures of actual icicles with their predicted shape. They found that it doesn’t matter how big or small the actual icicles were, they could all fit the shape generated by the mathematical equation. The next step is to solve the problem of how ripples are formed on the surfaces of both stalactites and icicles.

ICE, ICE, BABY: Ice is the frozen form of liquid water. The same substance will behave differently at various temperatures and pressures. Water (H2O) is the most familiar example. It can be a solid (ice), a liquid (water), or a gas (steam), but it is still made up of molecules of H2O, so its chemical composition remains unchanged. At sea level, water freezes at 32 degrees Fahrenheit (0 degrees Celsius) and boils at 212 degrees Fahrenheit (100 degrees Celsius), but this behavior changes at different altitudes because the atmospheric pressure changes. In fact, get the pressure low enough and water will boil at room temperature. The critical temperature/pressure point at which H2O changes from one form to another is called a phase transition.

The American Meteorological Society and the American Geophysical Union contributed to the information contained in the video portion of this report.

Sourced and published by Henry Sapiecha 12th June 2010



VORTEX2 Tornado Scientists Hit the Road Again

VORTEX2 Tornado Scientists Hit the Road Again

VORTEX2 researchers trailed this Wyoming twister during last spring’s expedition. Credit: Josh Wurman, CSWR

(PhysOrg.com) — In the largest and most ambitious effort ever made to understand tornadoes, more than 100 scientists and 40 support vehicles will hit the road again this spring.

The project, VORTEX2–Verification of the Origins of Rotation in Tornadoes–is in its final season: May 1st through June 15th, 2010.

VORTEX2 is supported by the National Science Foundation (NSF) and the National Oceanic and Atmospheric Administration (NOAA).

Scientists from more than a dozen universities and government and private organizations will take part. International participants are from Italy, Netherlands, United Kingdom, Germany, Canada and Australia.

The questions driving VORTEX2 are simple to ask but hard to answer, says lead scientist Josh Wurman of the Center for Research (CSWR) in Boulder, Colo.

• How, when, and why do tornadoes form?
• Why are some violent and long-lasting while others are weak and short-lived?
• What is the structure of tornadoes?
• How strong are the winds near the ground?
• How exactly do they do damage?
• How can we learn to forecast tornadoes better?

“Current warnings have only a 13-minute average lead time, and a 70 percent false alarm rate,” says Brad Smull, program director in NSF’s Division of Atmospheric and Geospace Sciences. “Can we issue reliable warnings as much as 30, 45 or even 60 minutes ahead of tornado touchdown?”

VORTEX2 scientists hope to find the answers.

They will use a fleet of instruments to literally surround and the supercell thunderstorms that form them.

An armada will be deployed, including:

• Ten mobile radars such as the Doppler-on-Wheels (DOW) from CSWR;
• SMART-Radars from the University of Oklahoma;
• the NOXP radar from the National Severe Storms Laboratory (NSSL);
• radars from the University of Massachusetts, the Office of Naval Research and Texas Tech University (TTU);
• 12 mobile mesonet instrumented vehicles from NSSL and CSWR;
• 38 deployable instruments including Sticknets (TTU);
• Tornado-Pods (CSWR);
• 4 disdrometers (University of Colorado (CU);
• weather balloon launching vans (NSSL, NCAR and SUNY-Oswego);
• unmanned aircraft (CU);
• damage survey teams (CSWR, Lyndon State College, NCAR); and
• photogrammetry teams (Lyndon State Univesity, CSWR and NCAR).

“VORTEX2 is fully nomadic with no home base,” says Wurman. Scientists will roam from state to state in the U.S. Plains following severe weather outbreaks.

“When we get wind of a tornado,” says Wurman, “we spring into action.”

More information: VORTEX2 Project: http://www.vortex2.org

Provided by National Science Foundation (news : web)

Sourced and published by Henry Sapiecha 7th June 2010

China’s Coming Age Of Invention

Rebecca Fannin, 06.07.10, 06:00 AM EDT

Now, everything is made in China–

but little is invented there.

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When will the familiar label “Made in China” switch to something more challenging: “Invented in China”? Not for another decade at least, according to investors and technology entrepreneurs who gathered recently at an event in Beijing to discuss the topic. (For video of the event, click here.)

Sure, some things are already being invented in China. Internet whizzes have pushed advances in mobile gaming and instant messaging. But many obstacles prevent a full-scale leap into widespread inventing.

One hurdle is culture. Entrepreneurs in China are still afraid of failure, noted Feng Deng of Northern Light Venture Capital. A failed startup in Silicon Valley is practically a badge of honor. In addition, entrepreneurs in China may be good at coding software, but they make for lousy managers. That often keeps their businesses from scaling.

Innovation in China comes largely by accident, not by design, said DCM investor Hurst Lin, one of the first generation of China’s returnee entrepreneurs from the West and co-founder of Chinese Internet portal Sina. Facebook and Google ( GOOG news people ) were accidents of imagination that was allowed to roam and think differently. Such breakthrough ideas could not have been the result of an upbringing in China, said Lin, where education needs to move toward critical thinking and away from sheer memorization.

Even so, Lin and others (including myself) hold out hope–and the expectation–that China will climb the innovation ladder quickly. Why? Necessity is the mother of invention. Many of the country’s 1.3 billion people are yearning for middle-class living standards and the cars and consumer goods that go with it. The market for homegrown innovation is there.

Major and rapid developments are coming in clean tech–an area that Northern Light’s Deng is focusing on with bets in energy-efficient lights, wind power and energy storage. Let’s hope some of these ideas can clean up China’s polluted cities.
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// Before China’s tech hubs join the same league as Silicon Valley, however, the country needs more collaboration among university labs and venture capital firms to work on breakthrough ideas. This method has worked well in Silicon Valley and in Boston. In Shanghai and Beijing I’m told that professors and scientists prefer not to share their intellectual capital with financiers.

Still, corporations worldwide are pouring more investment into Chinese R&D operations every day, a point made by Egidio Zarrella of KPMG.

One example is corporate America’s interest in Chinese biomedical research and development–an area of investment that is rapidly becoming as hot as clean tech. Pfizer ( PFE news people ) recently established a joint venture with Crown Bioscience to work on finding a cure for cancers common in Asia–predominantly lung cancer. While in Beijing, I got a tour of Crown Bioscience, which is located in an immense life sciences park close to the Great Wall.

Sourced and published by Henry Sapiecha 7th June 2010

ROBOTS AND THE FUTURE
May 27, 2010 7:41 AM PDT

Eric Berger, left, and Keenan Wyrobek of robotics specialist Willow Garage hosted an open house Wednesday evening to introduce the first round of PR2 robots being made available to researcher and developers.

With a mission to accelerate the advancement of open-source robotics software and development, Scott Hassan founded Willow Garage in late 2006. The Menlo Park, Calif., company has now awarded 11 institutions a chance to see what they can do with the PR2 robots.

Photo by James Martin/CNET

Sourced and published by Henry Sapiecha 7th June 2010

STAR POWER USING LASERS FOR ENERGY DRIVE

A view inside the National Ignition Facility’s target chamber, a space easily big enough for technicians to stand inside. It is hoped the NIF will eventually be a major source of carbon-free energy.

(Credit: Lawrence Livermore National Lab)

LIVERMORE, Calif.–Think clean energy is a fantasy? What if the power of a star was applied to the problem?

That’s the approach being explored at the National Ignition Facility, a huge-scale experiment in laser fusion based at the Lawrence Livermore National Laboratory here. Scientists are looking at NIF as a potential key to producing large amounts of carbon-free power.

It’s not known if the system will ever bear the kind of fruit the scientists and administrators who run NIF would like. Still, the facility is a scientific wonder that can transform a single laser beam no wider than a human hair into 192 beams–each of which is 18 inches wide. Together, the beams are designed to produce 4 million joules, the amount of power that would produce 4 million watts of power in a single second.

Using star power for a clean-energy future (photos)


The NIF was completed in early 2009 and eventually will be used by the U.S. Department of Energy, as well as technicians from national laboratories, fusion energy researchers, academics, and others. It is “the world’s largest and highest-energy laser, [and] has the goal of achieving nuclear fusion and energy gain in the laboratory for the first time,” according to the Lawrence Livermore National Lab, “in essence, creating a miniature star on Earth.”

This is serious high technology. The NIF employs a series of amplifiers and mirrors known as switchyards to route and split the original hair’s-width laser beam over a total distance of 1,500 meters. After being separated by pre-amplifiers into 48 beams, each beam is then split into four beams, and then all are injected into the 192 main laser amplifier beamlines, according to the NIF.

The hope is that NIF will be online as a power plant within 15 to 20 years. For now, the facility is a proof-of-concept system, albeit one comprising two 10-story buildings and more than $3 billion of investment. Eventually, the 192 laser beams reunite to focus on a target fuel pellet that is just millimeters in size, yet placed inside a target chamber that towers over the technicians who sometimes work inside.

And 192 laser beams of this magnitude create some serious heat. The theoretical maximum, according to LLNL retiree and docent Nick Williams, is 100 million degrees Celsius.

For now, because of the amount of power necessary to produce the beams, and the heat created, scientists are only able to fire the laser system once every two or three hours. Eventually, the idea would be to fire it many times a second.

And by 2030, it is hoped, the NIF will be helping produce commercial power and helping scientists and researchers better understand the nature of the universe. That, it would seem, would be a main benefit of producing what amounts to a small star, right here in the middle of Northern California.

On June 24, Geek Gestalt will kick off Road Trip 2010. After driving more than 18,000 miles in the Rocky Mountains, the Pacific Northwest, the Southwest and the Southeast over the last four years, I’ll be looking for the best in technology, science, military, nature, aviation and more throughout the American northeast. If you have a suggestion for someplace to visit, drop me a line. In the meantime, you can follow my preparations for the project on Twitter @GreeterDan and @RoadTrip.

Sourced and published by Henry Sapiecha 7th June 2010

Sharks Can Really Sniff out Their Prey,

and This Is How They Do It

Science (June 10, 2010) — It’s no secret that sharks have a keen sense of smell and a remarkable ability to follow their noses through the ocean, right to their next meal. Now, researchers reporting online on June 10th in Current Biology, have figured out how the sharks manage to keep themselves on course.


It turns out that sharks can detect small delays, no more than half a second long, in the time that odors reach one nostril versus the other, the researchers report. When the animals experience such a lag, they will turn toward whichever side picked up the scent first.

“The narrow sub-second time window in which this bilateral detection causes the turn response corresponds well with the swimming speed and odor patch dispersal physics of our shark species,” known as Mustelus canis or the smooth dogfish, said Jayne Gardiner of the University of South Florida. All in all, it means that sharks pick up on a combination of directional cues, based on both odor and flow, to keep themselves oriented and ultimately find what they are looking for.

If a shark experiences no delay in scent detection or a delay that lasts too long — a full second or more — they are just as likely to make a left-hand turn as they are to make a right.

These results refute the popular notion that sharks and other animals follow scent trails based on differences in the concentration of odor molecules hitting one nostril versus the other. It seems that theory doesn’t hold water when one considers the physics of the problem.

“There is a very pervasive idea that animals use concentration to orient to odors,” Gardiner said. “Most creatures come equipped with two odor sensors — nostrils or antennae, for example — and it has long been believed that they compare the concentration at each sensor and then turn towards the side receiving the strongest signal. But when odors are dispersed by flowing air or water, this dispersal is incredibly chaotic.”

Indeed, Gardiner explained, recent studies have shown that concentrations of scent molecules could easily mislead. Using dyes that light up under laser light, scientists found that there can be sudden peaks in the concentrations of molecules even at a distance from their source.

Gardiner’s team suggests that the findings in the small shark species they studied may help to explain the evolution of the wide and flat heads that make hammerhead sharks so recognizable. One idea has held that the characteristic hammerhead may lend the animals a better sense of smell. But studies hadn’t shown their noses to be all that remarkable, really. For instance, they don’t respond to odors at concentrations lower than other sharks. The new findings suggest that the distance between their nostrils could be the key.

“If you consider an animal encountering an odor patch at a given angle, an animal with more widely spaced nostrils will have a greater time lag between the odor hitting the left and right nostrils than an animal with more closely spaced nostrils,” Gardiner said. “Hammerheads may be able to orient to patches at a smaller angle of attack, potentially giving them better olfactory capabilities than pointy-nosed sharks.” That’s a theory that now deserves further testing.

In addition to giving insights into the evolution and behavior of sharks, the findings might also lead to underwater robots that are better equipped to find the source of chemical leaks, like the oil spill that is now plaguing the Gulf Coast, according to the researchers.

“This discovery can be applied to underwater steering algorithms,” Gardiner said. “Previous robots were programmed to track odors by comparing odor concentrations, and they failed to function as well or as quickly as live animals. With this new steering algorithm, we may be able to improve the design of these odor-guided robots. With the oil spill in the Gulf of Mexico, the main oil slick is easily visible and the primary sources were easy to find, but there could be other, smaller sources of leaks that have yet to be discovered. An odor-guided robot would be an asset for these types of situations.”

The researchers include Jayne M. Gardiner, University of South Florida, Tampa, FL, Center for Shark Research, Mote Marine Laboratory, Sarasota, FL; and Jelle Atema, Boston University Marine Program, Boston, MA, Marine Biological Laboratory, Woods Hole, MA, Woods Hole Oceanographic Institution, Woods Hole, MA.

Sourced and published by Henry Sapiecha 11th June 2010

Climate change killing lizards worldwide


SANTA CRUZ, Calif. (UPI) — Twenty percent of all lizard species could be extinct by 2080 because of rising temperatures involved in climate change, a California researcher said.

Lizards worldwide are far more susceptible to climate-warming extinction than previously thought because many species already live at the edge of their thermal limits, said Barry Sinervo of the Department of Ecology and Evolutionary Biology at the University of California, Santa Cruz.

Sinervo and colleagues from around the world said they reached their conclusions after comparing field studies of lizards in Mexico to lizard studies from other countries.

Rising temperatures already have driven an estimated 12 percent of Mexico’s Sceloporus lizard population to extinction, the scientists wrote in a recent issue of the journal Science.

“We are actually seeing lowland species moving upward in elevation, slowly driving upland species extinct, and if the upland species can’t evolve fast enough then they’re going to continue to go extinct,” Sinervo said in a release from the university Thursday.

Sourced and published by Henry Sapiecha 7th June 2010

Clam Cleanup

Biologists Clam Up Waterways

To Determine Sources Of Pollution

January 1, 2009 — Biologists are able to determine the sources of toxins in water by using clams as pollutant traps. Clams naturally clean water by feeding absorbing toxins in their tissues as they draw in water. By placing the clams downstream of industrial parks and highways, they can be analyzed for pollutants. Biologists open the clams after exposure to these waters and detach them from their shells– various lab tests reveal contaminants in the waterway.


See also:
Plants & Animals

Many of our streams and rivers are contaminated with pollutants like pesticides, lead, arsenic and PCBs. It’s a problem that’s costly to clean up. Scientists are using a new, inexpensive way to fix the problem.

Lurking in many rivers and streams are contaminants. Some you can see, and some you can’t. Hidden chemicals ruin waterways and everything in it. To clean things up, biologists are teaming up with local high school students to dredge up clams to use as tiny detectives. They help by finding the source of toxic leaks.

“We’re using them as pollutant traps,” said Harriette Phelps, Ph.D., a biologist at the University of the District of Columbia in Washington, D.C.

Students put the clams in streams that lead to rivers. Clams then suck in water swept down from industrial parks and highways.

“It’s been a great experience to actually come and see them and be the ones to pick them up out of the water,” student Caitlin Virta said.

Clams clean the water as they feed, absorbing toxins in their tissues. The clams are collected back from streams. Then, scientists pry open the clams and detach them from their shell. Later, lab tests reveals the clam’s secret — the kinds and quantities of pollutants in the water.

“We can trace them back to sources, and then hopefully we can go from there and get rid of the sources,” Dr. Phelps said.

The clams detected a banned pesticide in Maryland, believed buried years ago and now slowly leaking. “I thought it was really cool how you could tell the health of a stream from analyzing clam leftovers,” Virta said.

It’s a cool way to clean up the environment.


BIOACCUMULATION AND CLAMS: Clams are filter-feeders, meaning they draw water into their shells, remove the food they find, and then draw in more food-rich water to continue feeding. This means that lots of water works its way through their shells. The muscle of the clam gathers not only food, but other material suspended in water during this process, which can lead to the accumulation of toxins and pollutants. Bioaccumulation is the term for toxins and pollutants that collect in the tissue of an organism. Biomagnification is a related term, referring to the transfer of such substances from prey to predator. If a prey animal bioaccumulates toxins in its body, then its predator, after consuming many of the smaller animals will accumulate many, many times the amount of the toxin in any one of their prey.

SECONDARY STANDARDS: Even if your tap water meets the EPA’s basic requirement for safe drinking water, some people still object to the taste, smell or appearance of their water. These are aesthetic concerns, however, and therefore fall under the EPA’s voluntary secondary standards. Some tap water is drinkable, but may be temporarily clouded because of air bubbles, or have a chlorine taste. A bleach-like taste can be improved by letting the water stand exposed to the air for a while.

The American Geophysical Union contributed to the information

Sourced and published by Henry Sapiecha 7th June 2010


More cars vulnerable to computer hackers


SAN DIEGO (UPI) — Increasingly sophisticated cars need to be protected from hackers who could tamper with computerized systems, U.S. scientists said.

As more cars become connected to the Internet through wireless systems, hackers could remotely sabotage the vehicles, The New York Times reported Friday.

In tests, computer security experts at the University of Washington and the University of California, San Diego, said they were able to remotely control braking, stop the engine and activate dozens of other functions, almost all of them while a car was in motion.

The researchers tested two versions of a late-model car in laboratory and field settings. The researchers did not publicly identify the manufacturer or model, but said they believed the cars were representative of the computer network systems found in many late-model cars today.

“You should expect that various entry points in the automotive environment are no more secure in the automotive environment than they are in your PC,” said Stefan Savage, a computer scientist in San Diego.

Sourced and published by Henry Sapiecha 7th June 2010

Sterilizing, not killing, weeds suggested


WASHINGTON (UPI) — U.S. Agriculture Department scientists say using herbicides to sterilize instead of killing weedy grasses might be more economical and environmentally sound.

The USDA’s Agricultural Research Service said exotic annual grasses such as Japanese brome, cheatgrass and medusahead are harming millions of acres of grassland in the western United States. But herbicides used to control the invasive grasses also sometimes damage desirable perennial grasses.

In contrast, when used properly, scientists said growth regulators don’t greatly harm desirable perennial grasses and can control broadleaf weeds in wheat, other crop grasses and on rangelands.

ARS ecologist Matt Rinella and colleagues said they knew when dicamba and other growth regulator herbicides were applied to cereal crops late in their growth stage, just before seed formation, the plants produced far fewer seeds.

The scientists decided to see what occurred on the invasive weed Japanese brome. They found picloram (Tordon) reduced seed production nearly 100 percent when applied at the late growth stage of the weed. Dicamba (Banvel/Clarity) was slightly less effective but still nearly eliminated seed production, while 2,4-D was much less effective.

Rinella said since annual grass seeds only survive in soil a year or two, it should only take one to three years to greatly reduce the soil seed bank of annual weedy grasses without harming perennial grasses.

The research appeared in the journal Invasive Plant Science and Management.

Received and published by Henry Sapiecha 7th June 2010