Tag Archives: experiment

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).

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.

Moth Jams Bat Sonar

Superloud moth jams bat sonar

A gray moth with orange highlights called Bertholdia trigona “goes berserk,” making lots of noise above the range of human hearing when a hunting bat approaches, says William Conner of Wake Forest University in Winston-Salem, N.C. Bats rely on their natural sonar to locate flying moths in the dark, but in a lab setup, the bats rarely managed to nab a loud moth.

When researchers disabled the moth’s noisemaking organs, though, bats caught the moths in midair with ease, Conner reported at the annual meeting of the Society for Integrative and Comparative Biology.

Conner says the work is “the first example of any prey item that jams biological sonar.” Conference attendee David Yager of the University of Maryland in College Park says Conner’s experimental paradigm is “very strong, and I do think he has documented jamming by a species of moth.”

Insect-hunting bats and their moth prey have become a classic in the study of evolutionary arms races, Conner says. “This is warfare … The first counter-adaptation is that the insects developed ears.”
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Jamming isn’t the only possible explanation for moth noises, he said. An explosive clicking sound coming back out of the night might startle a bat just a split-second long enough for the moth to get away.

Rat Brain Cells, in a Dish, Flying a Plane

Adaptive Flight Control With Living Neuronal Networks on Microelectrode Arrays (open access paper) by Thomas B. DeMarse and Karl P. Dockendorf Department of Biomedical Engineering, University of Florida

investigating the ability of living neurons to act as a set of neuronal weights which were used to control the flight of a simulated aircraft. These weights were manipulated via high frequency stimulation inputs to produce a system in which a living neuronal network would “learn” to control an aircraft for straight and level flight.

A system was created in which a network of living rat cortical neurons were slowly adapted to control an aircraft’s flight trajectory. This was accomplished by using high frequency stimulation pulses delivered to two independent channels, one for pitch, and one for roll. This relatively simple system was able to control the pitch and roll of a simulated aircraft.

When Dr. Thomas DeMarse first puts the neurons in the dish, they look like little more than grains of sand sprinkled in water. However, individual neurons soon begin to extend microscopic lines toward each other, making connections that represent neural processes. “You see one extend a process, pull it back, extend it out — and it may do that a couple of times, just sampling who’s next to it, until over time the connectivity starts to establish itself,” he said. “(The brain is) getting its network to the point where it’s a live computation device.”

To control the simulated aircraft, the neurons first receive information from the computer about flight conditions: whether the plane is flying straight and level or is tilted to the left or to the right. The neurons then analyze the data and respond by sending signals to the plane’s controls. Those signals alter the flight path and new information is sent to the neurons, creating a feedback system.

“Initially when we hook up this brain to a flight simulator, it doesn’t know how to control the aircraft,” DeMarse said. “So you hook it up and the aircraft simply drifts randomly. And as the data come in, it slowly modifies the (neural) network so over time, the network gradually learns to fly the aircraft.”

Although the brain currently is able to control the pitch and roll of the simulated aircraft in weather conditions ranging from blue skies to stormy, hurricane-force winds, the underlying goal is a more fundamental understanding of how neurons interact as a network, DeMarse said.

Broken Window Theory Bolstered with Experiments

The broken window theory is that as the visible deterioration of an area (broken windows, graffiti, lettering…) takes place, crime will increase. And that this starts a cycle of decline for the area feeds upon itself (a negatively reinforcing loop in system thinking parlance). The theory was put forth in an article in The Atlantic in 1982 by George L. Kelling and James Q. Wilson.

Criminology Can the can, The Economist

Kees Keizer and his colleagues at the University of Groningen deliberately created such settings as a part of a series of experiments designed to discover if signs of vandalism, litter and low-level lawbreaking could change the way people behave.
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The most dramatic result, though, was the one that showed a doubling in the number of people who were prepared to steal in a condition of disorder. In this case an envelope with a â‚¬5 ($6) note inside (and the note clearly visible through the address window) was left sticking out of a post box. In a condition of order, 13% of those passing took the envelope (instead of leaving it or pushing it into the box). But if the post box was covered in graffiti, 27% did. Even if the post box had no graffiti on it, but the area around it was littered with paper, orange peel, cigarette butts and empty cans, 25% still took the envelope.

The researchers’ conclusion is that one example of disorder, like graffiti or littering, can indeed encourage another, like stealing. Dr Kelling was right. The message for policymakers and police officers is that clearing up graffiti or littering promptly could help fight the spread of crime.

Qubits Construction Toy

Buy Qubits – The Construction Toy via Amazon). Post suggestion provided through our suggest a post link. Children are naturally curious. We need to provide opportunities for them to do what they would do naturally. This is one nice way to let kids explore the physical world.

QubitsÂ® for Kids by Mark Burginger, architect / inventor

Many of us recognize the name, Frank Lloyd Wright. He was America’s most famous architect. However, did you know that he was closely connected with the construction toy industry? It just happens that his son, John Lloyd Wright invented Lincoln LogsÂ®. John traveled to Japan with his father Frank Lloyd Wright and while he was there John looked at the wooden log foundation his father designed for the Imperial Hotel, Tokyo. It caused him to think of a simple system of notched logs that could be used as a toy. After returning to the United States he created the toy sensation – Lincoln LogsÂ®.

You don’t need to be an architect of any stature approaching Frank Lloyd Wright to feel this sense of influence. The inspiration for me came from the same Lincoln Logs that John Lloyd Wright invented. I used to play with them for hours and hours on end as a child. Now as a parent and an architect I feel I should do my part to provide a unique construction toy for children to play with and draw inspiration. The toy that I have spent the last five years developing is coined with the name, QubitsÂ®. This dynamic new entry into the toy industry is gaining popularity with teachers, professors and of course – children all over Central Oregon. A simple plastic toy that can be built-up using a unique patented modular geometry. It quickly captures the imagination of children who might have visions of becoming architects, engineers, scientist or even nanotech designers.
Continue reading →

Incident in LHC Sector 34

Incident in LHC sector 34

During commissioning (without beam) of the final LHC sector (sector 34) at high current for operation at 5 TeV, an incident occurred at mid-day on Friday 19 September resulting in a large helium leak into the tunnel. Preliminary investigations indicate that the most likely cause of the problem was a faulty electrical connection between two magnets, which probably melted at high current leading to mechanical failure. CERN ’s strict safety regulations ensured that at no time was there any risk to people.

A full investigation is underway, but it is already clear that the sector will have to be warmed up for repairs to take place. This implies a minimum of two months down time for LHC operation. For the same fault, not uncommon in a normally conducting machine, the repair time would be a matter of days.

10 Most Beautiful Physics Experiments

Science’s 10 Most Beautiful Experiments by George Johnson

Galileo’s experiment on falling objects

In the late 1500’s, everyone knew that heavy objects fall faster than lighter ones. After all, Aristotle had said so. That an ancient Greek scholar still held such sway was a sign of how far science had declined during the dark ages.

Galileo Galilei, who held a chair in mathematics at the University of Pisa, was impudent enough to question the common knowledge. The story has become part of the folklore of science: he is reputed to have dropped two different weights from the town’s Leaning Tower showing that they landed at the same time. His challenges to Aristotle may have cost Galileo his job, but he had demonstrated the importance of taking nature, not human authority, as the final arbiter in matters of science.
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Young’s double-slit experiment applied to the interference of single electrons

Though it is not simply made of particles, neither can it be described purely as a wave. In the first five years of the 20th century, Max Planck and then Albert Einstein showed, respectively, that light is emitted and absorbed in packets — called photons. But other experiments continued to verify that light is also wavelike.

It took quantum theory, developed over the next few decades, to reconcile how both ideas could be true: photons and other subatomic particles — electrons, protons, and so forth — exhibit two complementary qualities; they are, as one physicist put it, ”wavicles.”

Eratosthenes’ measurement of the Earth’s circumference -the librarian at Alexandria in the third century B.C. estimated the circumference of the planet

Assuming the earth is spherical, its circumference spans 360 degrees. So if the two cities are seven degrees apart, that would constitute seven-360ths of the full circle — about one-fiftieth. Estimating from travel time that the towns were 5,000 ”stadia” apart, Eratosthenes concluded that the earth must be 50 times that size — 250,000 stadia in girth.

Related: Book, The Ten Most Beautiful Experiments by George Johnson (not the same experiments) – Home Experiments: Quantum Erasing – Particles and Waves – theory of knowledge – scientific experiments

MythBuster: 3 Ways to Fix USA Science Education

MythBuster Adam Savage: 3 Ways to Fix U.S. Science Education

Let students get their hands dirty.
It’s really difficult to absorb things just by being told about them—I know I don’t learn well that way. If students could get their hands dirty in science class they’d be more likely to internalize information. You can lecture about the surface tension of water, but it’s not as effective as conducting an experiment with a needle and a single beam balance. Jamie and I are in touch with a lot of teachers from industrial engineering programs, and one of them told us he thinks our show has helped shift the emphasis from the strictly theoretical to a more hands-on approach.

2. Yes, spend more money on science.
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3. Celebrate mistakes.
A good scientist will tell you that being wrong can be just as interesting as being right. The same holds for our show. We love hearing from fans who challenge our conclusions—especially kids.

Great Speech by Marissa Mayer on Innovation at Google

Marissa Mayer speech at Stanford on innovation at Google (23 minute speech, 26 minutes of question and answers). She leads the product management efforts on Google’s search products- web search, images, groups, news, Froogle, the Google Toolbar, Google Desktop, Google Labs, and more. She joined Google in 1999 as Google’s first female engineer. Excellent speech. Highly recommended. Google top 9 ideas:

(inside these are Marissa’s thoughts) [inside these are my comments]

Ideas come from anywhere (engineers, customers, managers, executives, external companies – that Google acquires)
Share everything you can (very open culture)
Your Brilliant We’re Hiring [Google Hiring]
A license to pursue dreams (Google 20% time)
Innovation not instant perfection (iteration – experiment quickly and often)
Data is apolitical [Data Based Decision Making – common errors in interpreting data – read the related links too]
Creativity loves Constraints [process improvement and innovation]
Users not money (Google focuses on providing users what they want and believe it will work out)
Don’t kill projects morph them

So far every time I hear one of Google’s leaders speak I am happier that I own a bit of stock – this is another instance of that.