Tag Archives: science explained

Antigen Shift in Influenza Viruses

Antigenic shift is the process by which at least two different strains of a virus, (or different viruses), especially influenza, combine to form a new subtype having a mixture of the surface antigens of the two original strains.

Pigs can be infected with human, avian and swine influenza viruses. Because pigs are susceptible to all three they can be a breeding ground for antigenic shift (as in the recent case of H1N1 Flu – Swine Flu) allowing viruses to mix and create a new virus.

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Lenz’s Law in Action: Eddy Current Tubes

Eddy Current Tubes — Drop the Magnets down the tube. An eddy current is set up in a conductor in response to a changing magnetic field. Lenz’s law predicts that the current moves in such a way as to create a magnetic field opposing the change; to do this in a conductor, electrons swirl in a plane perpendicular to the changing magnetic field.

Because the magnetic fields of the eddy currents oppose the magnetic field of the falling magnet; there is attraction between the two fields. Energy is converted into heat. This principle is used in damping the oscillation of the lever arm of mechanical balances.

Home Experiment: Deriving the Gravitational Constant

Deriving the Gravitational Constant by Joe Marshall

In the summer of 1985 I was at home convalescing and being bored. It occurred to me one day that if Cavendish could determine the gravitational constant back in 1798, I ought to be able to do something similar
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Cavendish cast a pair of 1.61 pound lead weights. I found a couple of 2-pound lead cylinders my dad had lying around. I used duct tape to attach them to a 3-foot wooden dowel. Cavendish used a wire to suspend the balance, I used nylon monofilament. To determine the torsion of the fiber, you wait until the balance stops moving (a day or two) and then you slightly perturb it. The balance will slowly oscillate back and forth. The restoring force is calculated from the period of oscillation. Cavendish had a 7-minute period. My balance had a 40 minute period (nylon is nowhere near as stiff as wire).

Cavendish used a pair of 350 pound lead balls to attract the ends of the balance from about 9 inches away. I put a couple of 8 pound jugs of water about an inch away. The next trick was to measure the rotation of the balance. Cavendish had a small telescope to read the Vernier scale on the balance. I used some modern technology. I borrowed a laser from Tom Knight (Thanks again!), and bounced it off a mirror that I mounted on the middle of the balance. This made a small red dot on the wall about 20 feet away. (I was hoping this would be enough to measure the displacement, but I was considering an interferometer if necessary.)

To my surprise, it all worked. After carefully putting the jugs of water in place, the dot on the wall started to visibly move. Within a few minutes, it had moved an inch or two. I carefully removed the jugs of water and sure enough, the dot on the wall drifted back to its starting position.

Very cool example of a home physics experiment.

The Amazing Rusting Aluminum

when aluminum rusts, it forms aluminum oxide, an entirely different animal. In crystal form, aluminum oxide is called corundum, sapphire or ruby (depending on the color), and it is among the hardest substances known. If you wanted to design a strong, scratchproof coating to put on a metal, few things other than diamond would be better than aluminum oxide.

By rusting, aluminum is forming a protective coating that’s chemically identical to sapphire—transparent, impervious to air and many chemicals, and able to protect the surface from further rusting: As soon as a microscopically thin layer has formed, the rusting stops. (“Anodized” aluminum has been treated with acid and electricity to force it to grow an extra-thick layer of rust, because the more you have on the surface, the stronger and more scratch-resistant it is.)

This invisible barrier forms so quickly that aluminum seems, even in molten form, to be an inert metal. But this illusion can be shattered with aluminum’s archenemy, mercury. Applied to aluminum’s surface, mercury will infiltrate the metal and disrupt its protective coating, allowing it to “rust” (in the more destructive sense) continuously by preventing a new layer of oxide from forming.

Electrolyzed Water Replacing Toxic Cleaning Substances

Simple elixir called a ‘miracle liquid’

The stuff is a simple mixture of table salt and tap water whose ions have been scrambled with an electric current. Researchers have dubbed it electrolyzed water
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Used as a sanitizer for decades in Russia and Japan, it’s slowly winning acceptance in the United States. A New York poultry processor uses it to kill salmonella on chicken carcasses. Minnesota grocery clerks spray sticky conveyors in the checkout lanes. Michigan jailers mop with electrolyzed water to keep potentially lethal cleaners out of the hands of inmates.

In Santa Monica, the once-skeptical Sheraton housekeeping staff has ditched skin-chapping bleach and pungent ammonia for spray bottles filled with electrolyzed water to clean toilets and sinks. “I didn’t believe in it at first because it didn’t have foam or any scent,” said housekeeper Flor Corona. “But I can tell you it works. My rooms are clean.”
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It turns out that zapping salt water with low-voltage electricity creates a couple of powerful yet nontoxic cleaning agents. Sodium ions are converted into sodium hydroxide, an alkaline liquid that cleans and degreases like detergent, but without the scrubbing bubbles. Chloride ions become hypochlorous acid, a potent disinfectant known as acid water.

“It’s 10 times more effective than bleach in killing bacteria,” said Yen-Con Hung, a professor of food science at the University of Georgia-Griffin, who has been researching electrolyzed water for more than a decade. “And it’s safe.”

There are drawbacks. Electrolyzed water loses its potency fairly quickly, so it can’t be stored long. Machines are pricey and geared mainly for industrial use. The process also needs to be monitored frequently for the right strength.

Very cool use of science: providing a green cleaning agent that is effective.

Open Science: Explaining Spontaneous Knotting

Shedding light on why long strands tend to become knotted

Anyone who has ever put up Christmas lights knows the problem: Holiday strands so carefully packed away last year are now more knotty than nice. In fact, they have become an inextricable, inexplicable, seemingly inevitable mess. It happens every year, like some sort of universal law of physics.

Which, it turns out, it basically is. In October, two UCSD researchers published the first physical explanation of why knots seem to form magically, not just in strands of Christmas lights, but in pretty much anything stringy, from garden hoses to iPod earbud cords to DNA.
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“We’re not mathematicians,” Smith said. “We’re physicists. Physicists do experiments.”

UCSD researchers constructed a knot probability machine that involved placing a single length of string in a plastic box, sealing it, then rotating the box at a set speed for a brief period of time.
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The experiment involved placing a single length of floppy string into a plastic box, sealing it, then rotating the box at a set speed for a brief time. The researchers did this 3,415 times, sometimes changing variables such as box size and string length.

Open access research paper: Spontaneous knotting of an agitated string by Dorian M. Raymer and Douglas E. Smith.

Above a critical string length, the probability P of knotting at first increased sharply with length but then saturated below 100%. This behavior differs from that of mathematical self-avoiding random walks, where P has been proven to approach 100%. Finite agitation time and jamming of the string due to its stiffness result in lower probability, but P approaches 100% with long, flexible strings.
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As L [length] was increased from 0.46 to 1.5 m, P increased sharply. However, as L was increased from 1.5 to 6 m, P saturated at 50%.
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Tripling the agitation time caused a substantial increase in P, indicating that the knotting is kinetically limited. Decreasing the rotation rate by 3-fold while keeping the same number of rotations caused little change in P.
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We also did measurements with a stiffer string and observed a probability of finding a knot would approach 100% with an substantial drop in P.

Yet another interesting case of scientists explaining the world around us (and the value of open science).

Why Does Hair Turn Grey as We Age?

A team of European scientists have learned why our hair turns gray as we age. Despite the notion that gray hair is a sign of wisdom, these researchers show that going gray is caused by a massive build up of hydrogen peroxide due to wear and tear of our hair follicles. The peroxide winds up blocking the normal synthesis of melanin, our hair’s natural pigment.

“Not only blondes change their hair color with hydrogen peroxide,” said Gerald Weissmann, MD, Editor-in-Chief of The FASEB Journal. “All of our hair cells make a tiny bit of hydrogen peroxide, but as we get older, this little bit becomes a lot. We bleach our hair pigment from within, and our hair turns gray and then white. This research, however, is an important first step to get at the root of the problem, so to speak.”

The researchers made this discovery by examining cell cultures of human hair follicles. They found that the build up of hydrogen peroxide was caused by a reduction of an enzyme that breaks up hydrogen peroxide into water and oxygen (catalase). They also discovered that hair follicles could not repair the damage caused by the hydrogen peroxide because of low levels of enzymes that normally serve this function (MSR A and B). Further complicating matters, the high levels of hydrogen peroxide and low levels of MSR A and B, disrupt the formation of an enzyme (tyrosinase) that leads to the production of melanin in hair follicles. Melanin is the pigment responsible for hair color, skin color, and eye color. The researchers speculate that a similar breakdown in the skin could be the root cause of vitiligo.

Weissmann added. “This study is a prime example of how basic research in biology can benefit us in ways never imagined.”

See full press release

Magenta is a Color

Electromagnetic spectrum chart from the Wikimedia Commons

Yes, Virgina, there is a magenta by Chris Foresman

There is a nasty rumor making its way around the interconnected series of tubes we call the Internet.
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As visible light enters the eye and strikes the cone cells, the cells send electrical signals along the optic nerve to the brain. This is how our body “senses” light. Our brain interprets those three separate sensations to produce the perception that we call “color.”
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The truth is, no color actually exists outside of our brain’s perception of it. Everything we call a color—and there are a lot more than what comes in your box of Crayolas—only exists in our heads. We define color in terms of how our brains process the stimuli produced by a mix of wavelengths in the range of 400–700nm hitting specialized cells in our eyes—”one, or any mixture, of the constituents into which light can be separated in a spectrum or rainbow,” says the OED. Elliot’s article might be better titled, “Magenta is not a single wavelength of electromagnetic radiation in the ‘visible’ spectrum, but our brain perceives it anyway.”

This is a great article that uses science to explain interesting details about our brains and how we perceive the external world.

Scientists Study Saskatchewan Meteorite

Scientists unravelling mysteries of Saskatchewan meteorite

Video surveillance cameras at motels and gas stations captured the flashes of brilliant light and the shadows they cast. A week later, Milley was part of the team led by U of C geologist and geophysicist Alan Hildebrand at Buzzard Coulee. It was she who spotted the first meteorite fragment in a frozen pond.

Later, she studied the flashes and shadows from the various surveillance and amateur videos. She used the information to plot the fireball’s path as it fell to Earth and then tried to figure out its orbit. Milley’s tentative conclusion, which she discussed in Saskatoon Monday, was that it didn’t look like the space rock came from beyond the orbit of Mars.

“It looks like it’s a very kind of tight inner solar system orbit,” she said. “It’s not something that’s extended into the asteroid belt.” If she’s correct, it would be the first time researchers have found debris from a meteorite so close to Earth, Milley said.

In terms of the composition, Milley and her colleagues have determined it’s a relatively common type of meteorite with a high iron content. However, there is still much more to learn about it, they say. More than 100 fragments have already been recovered, but this spring, researchers will be resuming their search for more.

Fast Fitness Forecast is False, it Takes Time

Fitness Isn’t an Overnight Sensation

“To make a change in how you look, you are talking about a significant period of training,” Dr. Kraemer said. “In our studies it takes six months to a year.” And, he added, that is with regular strength-training workouts, using the appropriate weights and with a carefully designed individualized program. “That is what the reality is,” he said.

And genetic differences among individuals mean some people respond much better to exercise than others
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Now, said Mr. Antane, who runs with a group in Princeton on Thursday nights, “everything changed — my outlook on life, who I hung out with, how I felt about myself.”

Our bodies evolved under conditions with much more exercise than we currently get if we sit in an office all day. And we had less food. It is no surprise with more food and less exercise that we gain weight. And given that the benefit of fat was to help us survive when we had little food out bodies don’t change overnight. If they did then our ancestors would have had much more difficulty surviving – the whole point was to provide a resource to tap in bad times. If that resource dissipated quickly it would not have helped much.