Monday, July 24, 2006

Sub Atomic non-Atomic Particles

The world of particle physics is filled with studies utilizing giant equipment to hurl atoms at each other, scientists with big egos (this stuff is filled with Einsteinian theory), and at least a few people with a sense of humor (one adjective used to describe an aspect of certain sub-atomic particles is "flavor"). Muons are one of the many particles physicists know about which are smaller than the smalles atom. The particles most commonly known are protons, neutrons, and electrons. If you ever have any doubts about their charges, just remember that neu-trons are neu-tral, and this clean joke: An atom walks into a bar and says to the bartender, "Hey Joe, I think I lost an electron." The bartender says, "Are you sure?" The atom replies, "I'm positive." i.e. electrons are negative and protons are postive. Electrons are the smalles of the three, but there are other particles which may be smaller.

Muons are smaller than protons or neutrons and are larger than electrons, even though they have the same charge. They are not usually found in atoms, but are rather a particle in a state of decay between other sub-atomic particles. When a muon is in the atom, the atom is much smaller than a normal atom, because its large mass pulls the atomic particles closer together, or they reside in a lower energy state. Muons, with their negative charge also have a counterpart with a positive charge, the antimuon.

Muons enter the Earth's atmosphere and come crashing to the ground at tremendous speed. Cosmic rays, not just a facet of science fiction, produce these and other sub-atomic particles. Muons decay from large pions, created in the upper atmosphere by these rays.

Because these particles are in a constant state of decay, i.e. are losing energy to their environment, any machine that detects them, will detect them at different rates depending on where in the atmosphere the machine is located. This is simply demonstrated by the two muon counters in Switerland. One, at Jungfraujoch, high in the Swiss Alps (often called "The Top of Europe), and another, down in Bern, are counting muons as you read this. Because of its much higher altitude, the Jungfraujoch counter intercepts more atmospheric muons than the Bern counter, by the time the muons have gotten down to Bern, more have decayed, and are no longer muons. This simple demonstration, complete with online counter and webcams is available at It's Einstein theory simplified.

Thursday, July 13, 2006

AM versus FM Radio

It occured to me while making a long trip up to the Canadian border last weekend and listening to a lot of radio, that the difference between AM radio and FM radio must have something to do with the stations I was receiving on my car's radio. I remembered something from a teacher in highschool about those fundamental differences, but my memory of the matter was like swiss cheese.

In simplest terms AM radio is radio which uses amplitude modulation to disseminate information. FM radio uses frequency modulation. This means that both methods use radio waves, comparatively long, slow wavelengths in the electromagnetic spectrum. These are at the opposite end from gamma and x-rays, if you consider that wavelengths in the visual spectrum fall somewhere in the middle.

Amplitude modulation refers to the height of the wave. If you were to draw a wave from an AM tranmission, it would look like the cross-section of an ocean wave, with peaks and valleys, except that some of the peaks would be higher than others. The change in amplitude, peak and valley height and depth, is what translates, with an AM receiver, into a radio broadcast. Its the equivalent of the bumps on a record. Tiny bumps in the vinyl grooves of a record are interpreted by the needle and arm on your record player to produce different pitches. An infinite combination of pitches is possible, and so long as we can hear them, any pitch in the audible range can be heard. Voila, a radio broadcast.

Frequency modulation alters the radio wave in the opposite way to produce a radio broadcast. Frequency refers to the number of peaks and valleys in the wave occur within a given period of time. FM radio uses a carrier frequency, which is actually a range of frequencies, and this range and the allocation of frequencies to different stations varries by country. The carrier frequency is overlayed with signal, i.e. what you want to hear, and the signal changes the frequency of the carrier to make larger or smaller gaps between peaks and valleys in the wave. These gaps correspond to the bumps in the grove of the record, same idea as AM radio, just the opposite implementation.

Interestingly, AM radio is generally of lower sound quality, as smaller changes in the amplitude tend to be lost as noise, and therefore AM radio is usually only used for talk radio broadcasts. The range of AM radio is different during the day and the night, and this is where it gets really interesting. during the day, AM radio signals reverberate across the surface of the Earth, and follow its contours, this is why AM radio reception may be so poor during the day if you are a long way from the source. Distortions in the Earth's surface, i.e. a mountain range, will impede the progress of the radio signal to your device. At night however, changes in the atmostphere which occur when the sun's rays are absent, allow AM radio to travel higher in the air, effectively carrying the AM signal farther from its source, over obstructions. This phenomenon applies to the more commonly used medium and short wave AM signals.

FM radio is clearer over longer distances from its source because its signal is transmitted using only changes in frequency. What this means is that the height of the FM waves is always the same, and only their spacing changes. If you get an FM signal during the day, it will be the same signal you get at night.

The energy of radio signals is conserved along the lines of the law of conservation of energy though, and no radio signal is infinite, as the power it is given at its source will dissipate the farther you are from that source. Increasing the power of a signal though is simply a matter of turning up the juice and pumping more electricity in. This is why stations with a larger budget have better reception, they can afford a higher energy bill.

Radio may also be transmitted in stereo, that means that two different parts of the broadcast may come out of two different speakers, adding a spatial demention to the sound you hear. This is an even more complicated topic however, and one who's explanation belongs to another time.

Thursday, July 06, 2006

What About Sourdough?

In my recent explorations of my new home, which was not entirely devoid of remnants from the former tenants, I came across a bread maker in one of the top shelves of the kitchen. As I have been determined to become a do-it-yourself bread maker for some time now, the bread maker was the perfect excuse to get a start on that, at least half-assedly.

One bread type that has always fascinated me for its flavor and origin is sourdough (yogurt does as well, for similar reasons, but that is the stuff for another post). Is the sour flavor from yeast or bacteria alive in the food? How does our body deal with the organisms which cause this inviting tangy flavor? The bread maker also turns out to be a perfect excuse to look to the web and research this topic further, here is what I found:

Sourdough is an old European method for collecting, keeping, and baking with yeast. Yeast occurs in many forms and species all over the place, including, apparently, the air around us. It is also found in the skins of wild grapes, and I imagine organic ones as well, and it is harmless. Yeast can be collected from the air using nothing more than a one-to-one mixture of flour and water in a jar with a cloth over it. If you set this out on your counter, yeast will collect in the mixture and grow and divide. Yeast divides rapidly, and while "budding" the process of dividing is a method of reproduction found in yeast, it is not the only one. In the process of growing and dividing, yeast gives off carbon dioxide and alcohol, hence the bubbles you will see in your yeast collector. Yeast is unique in that it is a single-celled organism that can break down complex carbohydrates, starches, and turn them into sugars for its own metabolism. The breaking down of these sugars is the cause of the CO2 and alcohol.

So what about the sour flavor? Sourdough starter is basically what results from this yeast collector. This mixture must be maintained every two or three days or so after it has started to cultivate the yeast, and this is done by removing a measure of the mixture and replacing it with fresh water/flour mixture for the yeast to consume, grow, and divide in. The mixture will also have a form of bacteria in it, lactobacilli, and this is for two reasons. The first is that bacteria is everywhere, and given the tools, it will grow. The second is that this particular form of bacteria can perform anaerobic respiration, creating energy for its use without oxygen, and the byproduct of this process is lactic acid. Why don't other forms of bacteria grow in this mixture and create a huge unsanitary mess? It turns out that this mixture is a very inhospitable environment for most everything except yeast and this bacteria, provided you provide fresh flour/water to feed it. This inhospitably is due to the alcohol, CO2 and lactic acid given off by the yeast and bacteria. So, not only can you collect yeast for baking bread straight out of the air, but a yeast collector is a terribly convenient arrangement for growing and storing it, without harm to you. Fancy huh?

Sourdough flavor then is the product of alcohol given off by yeast and lactic acid given off by lactobacilli. When used to make bread rise, sourdough starter gives its flavor over to the loaf. Do you taste a hint of sourdough in that ryebread you're eating? That might be because rye flour is often used for the sourdough starter mixture, and then to make rye bread. Whole wheat flour works as well.

Saturday, July 01, 2006

Lepidoptera in the News

As an advance notice for all you junkies of the newspaper science section, this coming Tuesday in a major national newspaper there will be a story about lepidoptera, that's butterflies and moths, and the people who collect them. This is an opportunity to plug the research I do and share some information about the growing world of "your own backyard."

Earlier this week a reporter came to my university with Dave Wagner of the University of Connecticut to do a piece about collecting caterpillars, moths, and butterflies. Dave Wagner is an entomologist and has made a career out of collecting, documenting, and protecting hundreds of insect species. His specialty is lepidoptera, and when it comes to this area, he wrote the book, literally. It's called Caterpillars of Eastern North America by Princeton Field Guides, and you couldn't find a better guide to the species you'll come across in this region of the country. He was the ideal person to contact for this newspaper story. He's in touch with my PI (that's primary investigator, or my boss) and invited the reporter and some amateur lepidopterists to come out collecting with my lab group. The main event was a nighttime "black-lighting" where lights, especially black lights or mercury vapor lights, are hung up in the woods and grasslands next to sheets which moths are drawn to in droves. No one is quite sure why this happens, though there are many explanations, but it's the most efficient way to collect the largest number of species in one go.

I don't want to give away any more of the story, I'll just say to look in unnamed newspaper's Tuesday science section on July 4th for more information. If the story doesn't make it in on that day, check back in a week. It's sure to be accompanied by some impressive pictures, or at least one of Dr. Wagner educating our motley crew.

To complement the piece, I've decided to present my own short list of interesting species you can find in your own back yard. Try by checking tree branches and shrubs for caterpillars, or by setting up a white sheet and blacklight somewhere in the wilderness at night for moths. Butterflies can be hunted during the daytime with an insect net and some determination, try fields with tall grasses and wildflowers first. As a reminder, most of the species out there are moths, and the exception to the rule are the butterflies. Many moths are brown or grey, but don't let that deter you, some are spectacular, either as caterpillars or as adult moths, and rival some of the flashier butterflies.

Here's my list:

For Best All Around, the award goes to the Eastern Tiger Swallowtail aka Papilio glaucus.

This is a familiar species to many as a butterfly, but it's got an equally impressive caterpillar or larva. The larva may be found on cherry, tulip tree, ash and other tree species. As a small larva it mimics a bird dropping and as an older larva it's a snake mimic. Those spots on the older green larva aren't it's eyes, but mimicking eye spots. The larva also has osmeteria which it can project out of a spot near its head to scare predators. The adult is magnificent.

For Flashiest Caterpillar, the award goes to the White-Marked Tussock Moth, or Orgyia leucostigma.

Complete with tufts of white or yellow hair, a red head, and a brightly collored body, this caterpillar is distinctive. It is found on just about every woody tree species in the Eastern United States and for much of the summer. The long hairs could cause an allergic reaction, though I haven't had that experience with this particular caterpillar.

For "Don't Touch Me" the award goes to the Saddleback Caterpillar, or Acharia stimulea.

This beauty can be found in many gardens, on apple trees or blueberry bushes, and a host of other plants. The spines at either end are stinging. If I were giving an award for the caterpillar for which you can't tell one end from the other, this guy would get it.

The award for uggliest caterpillar goes to a caterpillar in the same family as the Saddleback, the Monkey Slug or Hag Moth, aka Phobetron pithecium.

At first glance this caterpillar looks like a demonic spider, but on further inspection may actually appear cute and fuzzy. The moth isn't so bad looking either with a black and white pattern. Found on many tree species in the Northeast, Dr. Wagner says that there may be credence to the idea that the caterpillar mimics a shed tarantula skin, if the caterpillar is considered primarily a tropical species (tarantulas are found in the tropics and their coexistence with this caterpillar would be required for a true case of mimicry to occur).

Finally, the award for most stunning moth goes to the Luna Moth, or Actias luna.

This elusive and beautiful species will warm the heart of just about anyone lucky enough to lay eyes upon her. The caterpillar is a nice creature too, but the moth takes the top prize. A newly emerged moth will be a slow flyer and may be found at night with a blacklight. The cocoon of this moth is spun from silk, unlike many other caterpillars which make pupae that are hard and smooth. You should consider yourself lucky to see one of these moths, which may get up to the size of your hand with fingers extended, during your lifetime.

This is of course the shortest of lists, and you should see for yourself all the amazing species of caterpillars, moths, and butterflies out there right near where you live. Find one or find hundreds, you're sure to be entertained and amazed no matter which species you come upon. And, don't forget to check out that article this coming Tuesday.
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