Category: Science

Condition 1 weather at the Scott Base in Antarctica means that no one is allowed outside.

Condition 3

Must meet all of the following criteria:

• Visibility is either greater than ¹⁄₄ mile (400 m), or it falls to ¹⁄₄ mile or less for less than one minute at a time
• Windspeed is either below 48 knots (89 km/h; 55 mph), or it reaches 48 knots or above for less than one minute at a time
• Air temperature and wind chill are either above −75 °F (−59 °C), or falls to −75 °F or below for less than one minute at a time

Condition 2

Must meet all of the following criteria:

• Visibility is either greater than or equal to 100 feet (30 m), or it falls below 100 feet for less than one minute at a time
• Windspeed is either less than or equal to 55 knots (102 km/h; 63 mph), or it exceeds 55 knots for less than one minute at a time
• Air temperature and wind chill are either −100 °F (−73 °C) or above, or falls below −100 °F for less than one minute at a time

And also must meet one or more of the following criteria:

• Visibility is less than or equal to ¹⁄₄ mile (400 m), sustained for one minute or longer
• Windspeed greater than 48 knots (89 km/h; 55 mph), sustained for one minute or longer
• Air temperature and/or wind chill of −75 °F (−59 °C) or below, sustained for one minute or longer

Condition 1

Must meet one or more of the following criteria:

• Visibility less than 100 feet (30 m), sustained for one minute or longer
• Windspeed over 55 knots (102 km/h; 63 mph), sustained for one minute or longer
• Air temperature and/or wind chill below −100 °F (−73 °C), sustained for one minute or longer

The ability of electric eels to shock their prey with a 600-volt blast is well known, but exactly how the fish orchestrate their attacks has remained a question as murky as the waters they hunt in.

Now it looks as if eels use a high-frequency barrage of shocks to disable fish by mimicking their prey’s nerve signals and making their muscles contract. In essence, they hijack the muscles and remote controlling the prey to near-certain death (see video above).

And if a fish is hiding behind a rock or algae, the eel has another shock pattern that makes the fish muscles twitch involuntarily, giving away their hiding place to the formidable predator.

The experiments that untangled these mechanisms were devised and run byKenneth Catania at Vanderbilt University in Nashville, Tennessee. In a natural environment, Catania watched an eel hunting and measured its electric discharges. As the eel was poised to strike, it emitted a barrage of high-voltage electric pulses. This stopped the fish in its tracks, allowing the eel to catch it easily.

To work out what was happening, Catania anaesthetised fish, removed their brains, and dangled them behind an electrically permeable agar barrier in an eel tank. Worms were then put into the tank for the eels to feed on, and the electric zaps sent out to catch the worms also reached the fish.

After about 3 milliseconds, the fish’s muscles completely contracted.

A chemical injected into another brainless fish to stop its motor neurons working, and another fish with its spine removed helped to complete the picture: the electric shock makes the motor neurons fire and contract the muscles, and it happens without the need for the central nervous system.

Catania also discovered that a different, high-voltage, two-pulse signal fired out by the eel makes a fish within range twitch uncontrollably, giving away its position and allowing the eel to go after it with its conventional attack of series of high-voltage pulses.

This two-pulse signal seems to tell the eel whether possible prey is living when information is limited, such as in murky or rocky environments, where the prey is hidden, the researchers say.

How and why the eel evolved this ability is still unknown, says Catania.

“It is possible that lower voltages had a similar effect in the course of evolution,” he says. “Smaller ‘blips’ induced in prey neurons by the ancestral eel discharge added together over a short time,” he suggests.

“This is an immensely interesting and important finding for electric fish biology,” says Jason Gallant at Michigan State University in East Lansing. “The discharge patterns have been described previously, but the mechanism by which the discharges act on their poor prey was only supposed.”

That eels evolved to not only disable prey, but to also flush them out is a surprise, Gallant says, and he wonders if this behaviour is eel-specific or is seen in other fish, even those that can’t produce such a forceful zap.

The hypnotising patterns in these swirling soap films aren’t spontaneous: they’re being controlled by the invisible hand of electricity.

By applying an electric field to the suspended liquid, it starts to rotate. Changing the direction of the electric field can alter the direction of flow, and the field’s strength affects the speed of rotation.

“The rotating film is like a motor,” says Reza Shirsavar from the University of Zanjan in Iran and his colleagues, who created the set-up.

Their soap film was made from water, glycerine and detergent, a common recipe used in bubble-blowing mixtures. The rainbow of colours arises from the varying thickness of the soap film on the water.

But beyond stirring up your bubble bath, the technique could be applied to other types of films containing polar molecules. Liquid crystal films, for example, or compounds used to manufacture industrial chemicals, could be controlled in the same way.

Shirsavar’s team says the system could be used as a micro pump, perhaps even controlling the ebb and flow of fluids inside living systems.

The video was presented last week at the annual meeting of the American Physical Society Division of Fluid Dynamics in San Francisco, California.

White blood cells are an important part of your body’s immune system. They are vital for protecting you from invading bacteria or parasites. Your body is host to five different kinds of white blood cells, all of which are made in the bone marrow.

Each white blood cell lives for three to four days, then is replaced. How many white blood cells and what type you have in your body can give doctors a better understanding of your health. Elevated levels of white blood cells in your blood are a good indicator that you are suffering from an illness. This is because it means your body is sending more and more white blood cells to fight off infections.

An eosinophil count is a type of blood test that measures the quantity of eosinophils (a type of white blood cell) in your body. An eosinophil count is typically used to confirm a diagnosis rather than make a diagnosis. According to the American Association of Clinical Chemistry, eosinophils are particularly involved in immune responses to infections caused by parasites and allergic reactions (AACC, 2012).

Eosinophils have two distinct functions in your immune system. First, they destroy invading germs like viruses, bacteria, or parasites such as Giardia and pinworm. Eosinophils also create an inflammatory response.

Inflammation is both good and bad. It helps isolate and control the immune response at the site of an infection, but it also damages the tissue around it. Allergies are immune responses that often involve chronic inflammation. Eosinophils play a significant role in the inflammation related to allergies and asthma.

 

The U.S. Air Force considered trying to detonate a nuclear bomb on the moon during the late 1950s. A physicist who worked on the project said a single explosion would have been “microscopic,” with little impact. But what if the plans had been bigger—do we have enough nuclear weapons to push the moon out of orbit?

Not even close. Depending on where the detonation happened, sending the moon careening away from Earth would take somewhere between 10 billion and 10 trillion megatons of TNT. The most powerful nuclear device ever detonated, the Soviet Union’s “Tsar Bomba,” yielded the energy equivalent of 50 megatons of TNT. The current nuclear arsenal of the world could produce less than 7,000 megatons.

The moon is constantly edging away from us, though, without any human intervention. The moon’s pull drags a portion of the Earth’s water out of its natural position, creating bulges at each end of the planet. As Earth rotates, these bulges exert force on the moon, adding to its kinetic energy and making its orbit grow larger. On average, the moon floats 3 or 4 centimeters further away every year.

Life without the moon would be strange in the near term and disastrous in the long term. If the stabilizing influence of the moon disappeared, the Earth would begin to teeter dramatically on its axis, and seasons would no longer be constant. Over the long term, it’s possible the Earth could topple over, as apparently happened to Uranus, which orbits the sun on its side.

Cats tend to be simple, elegant drinkers. Dogs are not.

At a recent summit on fluid dynamics, researchers from Virginia Tech and Purdue tried to explain why, with charming video footage to help.

Cats and dogs both lap up liquids with their tongues, but new research describes in detail why dogs are inherently sloppier drinkers.

The findings also help to explain why large, hefty dogs produce more backsplash mess than tinier ones. This and more related info was discussed today during the presentation “How dogs drink water,” made at the American Physical Society’s Division of Fluid Dynamics Meeting held in San Francisco.

If the topic seems familiar, it’s because the research team has been analyzing pet drinking habits for a while.

“Three years ago, we studied how cats drink,” Sunny Jung, an assistant professor at Virginia Tech, said in a press release. “I was curious about how dogs drink, because cats and dogs are everywhere.”

Both cats and dogs cannot suck in liquids as humans can because their cheeks facilitate the lifestyle of a four-legged predator. Dogs are omnivores, but their wolf ancestors predominately prey on hoofed animals such as deer, moose, elk and caribou.

The prior research found that felines drink via a two-part process consisting of an elegant plunge and pull, in which a cat gently places its tongue on the water’s surface and then rapidly withdraws it, creating a column of water underneath the cat’s retracting tongue.

“When we started this project, we thought that dogs drink similarly to cats,” Jung said. “But it turns out that it’s different, because dogs smash their tongues on the water surface—they make lots of splashing — but a cat never does that.”

Jung and colleagues determined that when dogs withdraw their tongue from water, they create a significant amount of acceleration — roughly five times that of gravity — that creates the water columns, which feed up into their mouths.

To model this, Jung placed cameras under the surface of a water trough to map the total surface area of the dogs’ tongues that splashed down when drinking.

The researchers found that heavier dogs drink water with the larger wetted area of the tongue. This indicates that a proportional relationship exists between water contact area of the dog’s tongue and body weight, thus the volume of water a dog’s tongue can move increases exponentially relative to the dog’s body size.

The ladle-like canine tongue tip, when full of water, also requires that the dog must open its mouth more to take in the liquid. This further contributes to the splish-splashing.

Jung and his team could only go so far watching dogs drink to determine the underlying physiology. They had to have the ability to alter the parameters and see how they affected this ability. Since they could not actually alter a dog in any way, they turned to models of the dog’s tongue and mouth.

“We needed to make some kind of physical system,” Jung explained.

For their model, Jung and his colleagues used glass tubes to simulate a dog’s tongue. This allowed them to mimic the acceleration and column formation during the exit process. They then measured the volume of water withdrawn. They found that the column of water pinches off and detaches from the bowl of water, primarily due to gravity.

A dog will close its mouth just before the water column collapses back to the bowl.

Jung and his colleagues are now investigating the diving dynamics of plunging seabirds, the skittering motion of frogs and what happens to leaves when they respond to high-speed raindrops. Such findings are leading to a better understanding of fundamental properties of fluid dynamics that can be applied to technological advancements in everything from medical equipment to manufacturing machinery.

The plot thickens, or should it be the ice? The most detailed and comprehensive 3D map so far of Antarctica’s winter sea ice shows that big parts of it are much thicker and more smashed-up than we thought, in fact, three times as thick. Data from this map will help us fill in some of the biggest gaps in our global climate models.

The growth of Antarctic sea ice, which reached an all-time record extent this year, is one of the biggest geophysical changes that happen on Earth each year.

“It expands from about four to 19 or 20 million square kilometres each year. That’s more than twice the area of Australia,” says Rob Massom from the Australian Antarctic Division in Hobart. “And of course this has an immense effect on the ocean surface: it caps the interaction between the atmosphere and the ocean, and it creates a white ocean surface, so affects the energy balance.”

Exactly how that winter ice forms – how thick it gets and by what mechanisms – has remained a mystery, leaving a big uncertainty in our current climate models.

Maps revealing more winter Antarctic sea ice in recent years are based on 2D images taken from satellites. But the trouble with such data, says Guy Williams from the University of Tasmania also in Hobart, is that “we don’t get thickness and so therefore we don’t get total change in sea ice volume”.

Instead, Williams and colleagues used a robot submarine made by scientists at Woods Hole Oceanographic Research Institution in the US to produce detailed 3D maps of huge swathes of Antarctic sea ice. Using sonar, the submarine mapped three areas from different sides of the continent, which together make up an area equivalent to twice that of the UK (see video).

“We were surprised by what we saw,” says Williams. They saw ice that was much thicker than they expected, though the survey was not comprehensive enough yet to make strong conclusions about all the winter sea ice in Antarctica.

Previous estimates based on a number of very limited – and probably biased – methods like ship inspection and drilling suggested that only 20 per cent of the winter sea ice was thicker than 1 metre. This study found that 90 per cent of it is more than 1 metre thick, and indeed, 40 per cent is thicker than 3 metres.

The data also hints at how the ice might form, which will be crucial for building future models.

If ice were left to form on still water, it would grow to about 1 metre, says Williams. Once it gets that thick, the water underneath is insulated from the air and doesn’t easily freeze.

But the Antarctic sea ice is being buffeted by strong winds, which are being made even stronger by global warming. So it’s getting broken up and pushed up on top of itself, making room for more ice to form.

“We found that 50 per cent of the area was deformed and that was contributing to over three-quarters of the volume,” says Williams.

The ever-growing winter sea ice isn’t entirely surprising. But working out which factors are driving this growth will help scientists figure out what will happen in the future.

Williams says that one hypothesis was that ice formation could be driven largely by rising coastal winds breaking up the ice, allowing more to form in the gaps. People are starting to wonder if the deformation processes are changing” he says.

“It’s extraordinarily significant work,” says Massom. “These autonomous underwater vehicles, they’re giving an unprecedented view. It’s almost like looking at the dark side of the moon in terms of sea ice.”

Journal reference: Nature Geoscience, doi.org/xcg

There are key differences between white and dark meats, but nutritionally, they’re more similar than not. The video above details the biological mechanisms behind different cuts of turkey…

In a turkey the active muscles such as the legs store a lot of oxygen and become dark, while less active muscles like the breast remain white.

Turkeys can fly short distances — typically from ground to perch — but they are not known for their sustained flying abilities. They rely on their legs to get them around. The active muscles, such as the legs and thighs, are full of blood vessels. These blood vessels contain myoglobin (or muscle hemoglobin), which delivers oxygen to the muscles. The more myoglobin the muscles contain, the darker the muscle.

Scientists often refer to these active muscles as slow-twitch fibers. Slow-twitch fibers are built for endurance, which allows the muscles to work for long periods of time. Thus the turkey can run around all day without getting tired.

On the other hand, white meat is the result of well-rested muscles. The breast muscles, which are used for flying, are hardly used by turkeys. There is no need to have a rich supply of oxygen delivered to these muscles. Scientists refer to these types of muscles as fast-twitch fibers. Fast-twitch fibers are designed for quick bursts of energy, but they fatigue quickly. In addition, fast twitch muscles are fueled by glycogen (carbohydrate stored in body tissues) giving the muscles that immediate explosion of energy needed to move rapidly.

Deep-sea anglerfish are strange and elusive creatures that are very rarely observed in their natural habitat. Fewer than half a dozen have ever been captured on film or video by deep diving research vehicles. This little angler, about 9 cm long, is named Melanocetus. It is also known as the Black Seadevil and it lives in the deep dark waters of the Monterey Canyon. MBARI’s ROV Doc Ricketts observed this anglerfish for the first time at 600 m on a midwater research expedition in November 2014. We believe that this is the first video footage ever made of this species alive and at depth.
Watch a video about a different type of anglerfish observed by ROV Doc Ricketts for the first time: https://www.youtube.com/watch?v=Cl_Mb…

For more information:
http://www.mbari.org

Video producer: Susan vonThun
Script and narration: Bruce Robison

Demonstration of Schlieren Optics, a technique that allows us to see small changes in the index of refraction in air. A point source of light is reflected from a concave mirror and focused onto the edge of a razor blade, which is mounted in front of the camera. Light refracted near the mirror and intercepted by the blade gives the illusion of a shadow.
Seen here are the heated gases from a candle flame and a hair dryer, helium gas, and sulfur hexafluoride gas.

For more information on the setup please see
http://sciencedemonstrations.fas.harv…

Note that this version of the setup uses a white LED flashlight instead of an automotive light bulb.