How Honey Bees Navigate

Rebecca Reilly
Period G
5/18/17

How Honeybees Navigate 

Scientists believe that bess can become the model organism for studying magnetoreception.

Navigation

According to a team of physicists and biologists in Canada, honey bees sense magnetic fields using a magnetic structure in their abdomens. By carrying out a series of physics and behavioral experiments on insects, it showed that the sensory ability that the bees have can be disrupted using a strong magnet. The underlying mechanisms of magnetoreception is what make this navigation possible. Magnetoreception is s a sense which allows an organism to detect a magnetic field to perceive direction, altitude or location. Bees contain magentite from a ferromagnetic oxide of iron that is also found in some types of rock. Honey bees respond to local magnetic fields in a way that is consistent with magnetite-based magnetoreception. This proves that a ferromagnetic material containing magnetite exists in the abdomen of honey bees. This material can be magnetized by using a strong permanent magnet that magnetizing the abdomen of a live honey bee disrupts its ability to navigate using local magnetic fields.

Evidence

The researchers first dissected a number of honey bees. They separated the bodies into different parts representing the anatomy of the bee: the abdomen, the thorax, and the head before crushing the body parts into pellets. Then they used a Superconducting Quantum Interference Device (SQUID) to measure the magnetization of each pellet after it was exposed to a magnetic field. The data showed that there was no evidence of ferromagnetism in pellets made from the thoraces and heads, but there was clear evidence of ferromagnetism for the abdomen sample. After, a strong permanent magnet was used to expose live honey bees to a magnetic field of 2.2 kOe, which is several thousand times stronger than the Earth's magnetic field, for about 5 seconds. Further results with the SQUID revealed that pellets made from the abdomen of these bees were more strongly magnetized than pellets made from bees that had not been exposed to a magnetic field.

 

Magnetization affects the ability of bees when they navigate a food source. In order to prove this, scientists trained a group of bees to locate sugar in an environment where electrical coils create a magnetic field. Half of the trained bess were magnetized and the other half of the train bees were not. The two different groups of bees were then compared to each other. Scientists found out that the magnetized bees were unable to find the sugar. This means that their magnetoreceptors had been disrupted by the magnetization process. Even though the study does not provide direct information about the biological mechanisms involved in magnetoreception, one of the scientist, Hayden, says: "The fact that we were able to disrupt the magnetic sense may well help to open doors or provide traction for future lines of inquiry.” Hayden also adds that him and the rest of the scientists hope to eventually answer questions “such as the potential impact of industrial electromagnetic noise on the bees' magnetoreceptor and their overall well-being". Hayden believes that future experiments could investigate the microstructue  of the magnetoreceptor. 

Three-Dimensional Direction-Dependent Force Measurement on the Subatomic Scale

Atomic force microscopy (AFM) is an extremely sensitive technique that allows us to image materials and/or characterize their physical properties on the atomic scale by sensing the force above material surfaces using a precisely controlled tip. However, conventional AFM only provides the surface normal component of the force (the Z direction) and ignores the components parallel to the surface (the X and Y directions).

To fully characterize materials used in nanoscale devices, it is necessary to obtain information about parameters with directionality, such as electronic, magnetic, and elastic properties, in more than just the Z direction. That is, it is desirable to measure these parameters in the X and Y directions parallel to the surface of a material as well. Measuring the distribution of such material parameters on the atomic scale will increase our understanding of chemical composition and reactions, surface morphology, molecular manipulation, and nano-machine operation.

A research group at Osaka University has recently developed an AFM-based approach called "bimodal AFM" to obtain information about material surfaces in the X, Y, and Z directions (that is, in three dimensions) on the subatomic scale. The researchers measured the total force between an AFM tip and material surface in the X, Y, and Z directions using a germanium (Ge) surface as a substrate. Their collaborative partner, the Institute of Physics of the Slovak Academy of Sciences, contributed computer simulations of the tip-surface interactions. The bimodal AFM approach was recently reported in Nature Physics.

"A clean Ge(001) surface has alternately aligned anisotropic dimers, which are rotated by 90° across the step, meaning they show a two-domain structure," explains first author Yoshitaka Naitoh. "We probed the force fields from each domain in the vertical direction by oscillating the AFM tip at the flexural resonance frequency and in the parallel direction by oscillating it at the torsional one."

The team first expressed the force components as vectors, providing the vector distribution above the surface at the subatomic scale. The computer simulation supported the experimental results and shed light on the nature of chemical tip termination and morphology and, in particular, helped to clarify the outstanding questions regarding the tip-surface distances in the experiment.

"We measured the magnitude and direction of the force between the AFM tip and Ge surface on a subatomic scale in three dimensions," says Naitoh. "Such measurements will aid understanding of the structure and chemical reactions of functionalized surfaces."

The developed bimodal AFM approach will allow researchers to investigate the physical properties of materials in greater detail on the nanoscale, which should facilitate development of devices, nanotechnology, and friction/lubrication systems.

The Physics of the Acoustic Guitar

The Physics of the Acoustic Guitar

• The guitar is the most common stringed instrument, and shares many characteristics with other stringed instruments.
• For example, the overtones potentially available on any stringed instrument are the same.
• The guitar sound so much different from a violin because of the overtones that are emphasized in a particular instrument, due to the shape and materials in the resonator (body), strings, how it's played, and other factors.
• The overtones, or harmonics of a string fixed at both ends play a role.

Waves on a String

• A guitar string is a common example of a string fixed at both ends which is elastic and can vibrate. The vibrations of such a string are called standing waves, and they satisfy the relationship between wavelength and frequency that comes from the definition of waves
• The equation for this is v = f,
• V is the speed of the wave, f is the frequency and is the wavelength.
• The speed v of waves on a string depends on the string tension T and linear mass density µ, measured in kg/m.
• Waves travel faster on a tighter string and the frequency is therefore higher for a given wavelength.
• Waves travel slower on a more massive string and the frequency is therefore lower for a given wavelength.
• The relationship between speed, tension and mass density is v = T/µ.
• Since the fundamental wavelength of a standing wave on a guitar string is twice the distance between the bridge and the fret, all six strings use the same range of wavelengths.
• To have different pitches (frequencies) of the strings, then, one must have different wave speeds.
• There are two ways to do this: by having different tension T or by having different mass density µ.
• If one varied pitch only by varying tension, the high strings would be very tight and the low strings would be very loose and it would be very difficult to play.
• It is much easier to play a guitar if the strings all have roughly the same tension and for this reason, the lower strings have higher mass density, by making them thicker and, for the 3 low strings, wrapping them with wire.
• From what you have learned so far, and the fact that the strings are a perfect fourth apart in pitch, you can calculate how much µ increases between strings for T to be constant.

String Harmonics (Overtones) If a guitar string had only a single frequency vibration on it, it would sound a bit boring. What makes a guitar or any stringed instrument interesting is the rich variety of harmonics that are present. Any wave that satisfies the condition that it has nodes at the ends of the string can exist on a string. The fundamental, the main pitch you hear, is the lowest tone, and it comes from the string vibrating with one big arc from bottom to top: fundamental (l = /2) The fundamental satisfies the condition l = /2, where l is the length of the freely vibrating portion of the string. The first harmonic or overtone comes from vibration with a node in the center: 1st overtone (l = 2/2) The 1st overtone satisfies the condition l = . Each higher overtone fits an additional half wavelength on the string: 2nd overtone (l = 3/2) 3rd overtone (l = 4/2) 4th overtone (l = 5/2) Guitar Overtones The thing that makes a guitar note "guitar" is the overtone content and how the note rises and decays in time. This varies with how you play it, such as with a pick or. a finger, or near the bridge vs. in the middle. Summary A guitar string sound consists of standing waves: the fundamental and overtones. The fundamental wavelength is twice the length of the vibrating part of the string. The Western musical scale is based on the overtone series for a string: all the overtones up to the 9th are close to notes of the equal-tempered scale. The timber of a stringed instrument depends on the overtone content of the sound: a "twangy" sound has both odd and even multiples of the fundamental, while a "smooth" sound tends to have only odd multiples. Jared Blatt Period G

Physics of Drums

Dating back to the slave trade the drum has been used all over the world as a means of communication and self-expression. Its broad variety of users includes the early African tribes and the Native Alaskan tribes, both using them for ceremonial purposes. The Africans brought drums with them to the Americas and helped to develop their popularity among American musicians. In the mid-1900’s drum sets were brought about.

These revolutionary collaborations of percussive pieces started off with a pair of hi-hats, a bass and snare drum, and a couple of tom-toms. Later as the music progressed, so did the drum kits, completely eliminating the need for an entire drum section. With the coming of the rock and roll movement the drum kits were changing, they needed to accommodate the new music styles. They became sonically diverse and even electronic drums were brought about; making them infinitely adjustable both ergonomically and musically.

The sound waves for open-ended and string instruments is fairly straight forward. However, for a closed-end instrument, such as a drum, the sound waves are different. A lot of the energy is dissipated through the shell of the drum, which is the reason for the variance in drum construction these days. Many different kinds of wood are used to generate different sounds or a different amount of energy absorption. For a warmer, deeper sound maple construction is used while birch is used to get a high, resonant tone full of vibration. The heaviest wood that dissipates the most amount of energy is oak, creating a lower, flat sound.

When the wooden shell construction isn’t enough for drummers to achieve the right amount of sound wave dampening, different drum heads are used. The thicker the drumhead the lower the sound and the higher the volume, likewise in contrast the thinner the drumhead the more the drum can resonate and vibrate freely. Another factor determining the sound of a drum is the tension at which the drumhead is tightened. With a higher tension comes a higher pitch, while a lower tension generates a lower pitch sound.

Physics and Billiards

Physics can be found anytime, anywhere. Billiards is one game where the more you know about physics the better a player you will be. Some of the main physics principles which can be found in Billards are Newton's Laws, conservation of momentum, inertia, and various laws of friction.

Newton's Laws are made up of three statements, all of which are found when it comes to billiards: the first law, an object in motion tends to stay in motion while an object at rest will stay at rest, unless acted upon by an outside force; the second, force is proportional to mass times the acceleration; and the third, for every action, there is an equal and opposite reaction.

The Conservation of Momentum takes place in an isolated system, a system with no outside force acting upon it. Here, the total momentum will remain constant.

Inertia, the tendency an object has to follow the same path all the time and not change its motion, is found when a ball is hit.

Various forms of friction can also be found. Sliding friction, for example, is the friction on an object while it is moving. There is also static friction which is the friction that acts on an object that is stationary.

There are a few different techniques to striking the cue ball and each will give different results. When you hit the center ball, the cue ball slides for a ways, and then rolls.

A draw is achieved by hitting the cue ball below center. First, the ball rotates backward. This rotation slows as the ball slides, and then the ball rolls forward as it does on other shots. The harder you shoot, the farther the ball will travel with this backward spin. And the lower you cue the ball, the farther the ball will travel with this backward spin.

The opposite of a draw is a follow. This is achieved by hitting the cue ball above center. The cue ball then rotates forward. If the cue ball then hits another ball, it will roll forward after the collision.

A stop shot is when the cue ball is very close to the object ball and can be accomplished with center ball. The cue ball slides to the object ball and stops dead as the object ball shoots ahead because of the collision.

There are two different types of collisions, elastic and inelastic. In the game of Billiards, the most common type of collision is the elastic collision.

With an elastic collision each ball will move in different directions, the trick is to get them to move in the direction you want them to move in.

Why are my shoelaces always untied?

Gabriella Pedro
Mr. Gray
Physics .1 - Period G
5/2/17

"Hey, your shoe is untied!"

Have you ever wonder why your shoelaces are always untied? Well scientist are curious and after extensive research they now know why. With the combination of foot stomping and leg swinging it causes our laces to slip apart!

You may be thinking to yourself "seriously I could of guessed that," but there are important reasons why scientists have given knots a closer look behind the obvious.

What is so special about a shoelace? Why do scientists care about my shoelaces? These questions are all valid but I can assure you that there is indeed a reason for this research. The reality is that knots are everywhere, from strands of DNA to stitches used in surgery to steel cables used in construction. Taking a closer look on why knots come undone could help scientist better understand not only shoelaces but also other object that consist of knots. 

The University of California at Berkeley came together with a group of mechanical engineers to become better intrigued with knot strength after coming across a TED talk that explained the two different ways to tie a shoelace. There are two ways to tie the classic bow tie knot, one of which is stronger than the other. The weaker version is the “granny knot”: take a rope, cross both ends left over right, bring the left end under and out, and repeat. The stronger version is the square knot: instead of repeating the first step, finish the knot by crossing the right end over the left.

“I wear dress shoes, and my shoelaces seem to come untied all the time,” says study lead author Christopher Daily-Diamond. “But when we looked into it, while people knew one of these knots was stronger than the other, the mechanics of why that was remained a mystery.”

In order for researcher to completely study shoelaces that must add sensors to the laces. The candidates wearing the sensors also repeatedly swung a pendulum arm with a shoelace knot tied on it to better analyze forces knots experience. This test provided great results that helped solve the puzzle. 

Study Showed:  
"Slow-motion videos of Gregg running on a treadmill showed the granny knot held together for many strides, but when it only slightly loosened, the knot typically failed catastrophically within as few as two strides. Intriguingly, the weak knot did not untie itself when Gregg’s leg was just swung back and forth, nor when the foot was only stomped repeatedly on the ground. This suggested that knot failure is based on some interplay between the swing and stomp."

Results shoes that the repeated impact of shoes on the floor during running loosens the knots. The sensors revealed that during running, feet strike the ground with seven times the force of gravity, causing knots to deform. While walking or running the whipping motions of the free ends of the laces caused by swinging legs then led the laces to slip, eventually leading to knots coming undone. 
                 

          

Researchers say: 

"In line with this theory, adding weights to the free ends of the laces, which increased the pulling those ends experienced as they swung, led knots to fail more often. Daily-Diamond, Gregg and senior author Oliver O’Reilly detailed their findings online April 12 in the journal Proceedings of the Royal Society A. "

So why study knots?
Daily-Diamond has noted that researchers today are trying to build microscopic structures of DNA and other molecules and to have success scientists must first fully understand knots and how they work. “These can be incredibly complicated knotted structures that are subject to a variety of forces, so if you want to start building these structures, you’ll want to know how they can become untied,” Daily-Diamond said.

Bending Sheet Glass with Lazers and Gravity

A brand new Fraunhofer technique is allowing for the bending and complex shaping of sheet glass. A laser is used to accomplish this difficult task, and the end result is new designs and shapes that we may have never seen before. This is a huge step forward for architects, as they can now use sheet glass as a viable building piece and shape it any way they want. 

So how is this accomplished? Scientists begin by heating the extremely thin piece of glass, about 4 mm, to just below the point where the glass would melt. After this, they begin to set up the laser. A path and series of movements is programmed into a computer which controls the laser. The laser moves on a path, stops, and changes direction many times to accomplish this. Now gravity does its job. At the points where the laser has heated the glass enough to melt, the glass begins to drip down at those spots, similarly to honey. This leads to many shapes and designs being created. This technique works so well with sheet glass, because unlike metal, which has a definitive melting point, glass can be heated up to a point where it is not melted, but rather malleable, making it much easier to shape.

So why is this such a big deal? Well, now architects and designers have a brand new material to work with, one much more efficient in creating intricate designs than other materials previously used. Tobias Rist, one of the researchers on this project, said "Thanks to our technique, manufacturers have a cost-effective way of producing extremely customized glass objects in small batches or even as one-offs," So, it is much more cost-effective and useful.

Peyton Phillips