28 July 2006

Archeology Part II

A few months ago I attended the Titanic exhibit at the San Francisco Metreon. (Highly recommended!) It included the "Big Piece", a 20' by 25' piece of the Titanic's hull. The piece was preserved by Conservation Solutions; their Titanic case file describes how the piece of hull was protected as it was brought to the surface.

The steel piece was desalinized by soaking in a pool of solution with aluminum/magnesium blocks. I tried to figure out why this works by comparing aluminum, magnesium, and iron (the main component of steel) in a reactivity series and confirmed that magnesium and aluminum are both more reactive than iron. These metals displaced the iron in reactions with sodium chlorides. Gradually the salts moved out of the hull piece to the alloy blocks. This process took almost two years. Then the piece was cleaned and coated with wax to protect it from new contaminants.

The Titanic exhibit explained that items that have been in salt water for so long are fragile when brought to the surface because molecules of the original item have been replaced by microorganisms and salts, and when a piece is cleaned and dried out, particles are removed which are now instrumental in the structural integrity of the item. The restored pieces are injected with wax to stabilize them.

Another fascinating thing about the Titanic exhibit: each visitor is given a boarding pass with information about a passenger on the ship. The exhibit includes a passenger list so you can see whether your passenger made it or not. My ticket was for a French model traveling as the companion (presumably the mistress) of San Francisco filmmaker. She didn't survive the sinking. The body of her travel companion was recovered with her purse clutched in his hand.

Archeological Finds

Just in the last few days, nifty things have been found in the ground.

In Jamestowne, Virginia, excavation of a well has yielded artifacts believed to be among the oldest items of European origin found in North America. Settlers arrived in 1607; a halberd was found bearing the insignia of Lord Delaware, who arrived in Jamestowne in 1610.

Associated Press Story
More about the Jamestown finds

And in Dublin, Ireland, a backhoe operator working in a bog discovered a Book of Psalms believed to be about 1200 years old, dating back to times of Viking raids in Ireland. Vikings!

More info and good photo

Preservation of these artifacts, especially the book, is crucial once the items are removed from the environment which has preserved them for hundreds of years. An article about shoes found in Salem, Massachusetts describes the proper preservation of leather items:

Current conservation practice entails soaking the leather items in water until they are chemically neutral and then immersing them in ethanol (alcohol) until the water is displaced and all bacteria is removed.

More about artifact preservation in Part II!

Popeye Soup

I've had major blogging paralysis lately, but while I am pulling ideas together into something coherant, here's a pointer towards this wonderful recipe I've been obsessed with lately:
Yummy yummy spinach soup

(It is a fabulous shade of green!)

18 July 2006

Etymology Part III: Drinking from the firehose

J came home with this expression one day, and I immediately adopted it. Drinking from the firehose means you are overwhelmed in some way, involved in something intense in which it is hard to stay caught up.

I was surprised that I could find examples of this phrase in use, but no explanation of where it came from. Even the Urban Dictionary, which usually provides me with something amusing if not downright useful, came up blank.

I have been told that "drinking from the firehose" refers specifically to being inundated with information from the Internet. Indeed, some of the links I found using this expression are related to the explosion of data created by the proliferation of the web each year.

Another possible source of the term is its usage at MIT, where the expression is used to describe the experience of being a student there. Since MIT is, in fact, steeped in the developement of technology, it would not be difficult to imagine the phrase crossing over (from describing education to describing the Internet) at this point.

I also found evidence that the phrase is being used more generally. My rather perfunctory Google search turned up examples of the phrase used to describe an Italian language immersion program and a flight training program at United Airlines.

I submitted the phrase to the Urban Dictionary, and it was published today.

More About the Penny

Hey look, my interest in the one-cent piece is timely: apparently there is a bill being introduced that would make the penny obsolete. I read it in today's headlines.

I hadn't really thought about the fact that a nickel is actually mostly copper, and that particular states would benefit from eliminating the penny because of copper mining.

US five-cent nickel

composition: 75% copper, 25% nickel
mass: 5.000 grams
volume: .5609 cc
value of metal: $0.06669

So, as with the copper penny of pre-1982, the metal in a nickel appears to be worth more than the nickel itself. Does this mean it would be better for the economy to use five (post-1982) pennies instead of a nickel? Or does the production cost of making five pennies (as opposed to a single nickel) make this equally expensive?

The CNN article states that the total cost of producing a penny is $0.014. Using my calculation that a modern-day penny contains $0.00884 of metal, we can conclude that the cost of minting a coin is about $0.0052. Five pennies would cost 5 x $0.014 = $0.070. If we assume that minting a penny and minting a nickel cost the same, a nickel's total cost to the US Mint would be $0.06669 + $0.0052 = $0.072. Five cents in coin costs the US Mint about seven cents if you're using pennies, but it costs slightly more if you're using a nickel.

(If you're interested in this penny debate, check this out.)

16 July 2006

The Value of a Penny

My big project this month is studying chemistry; because all the entry-level chem classes at City College are already closed, and I don't get to register until August, my best bet for getting into a chemistry class this fall is to learn enough material to pass a placement test into a middle-level course. This means learning AP Chemistry in a month. (I could have saved myself a lot of work if I had embraced my inner geek in 10th grade rather than trying to write angst-ridden poetry.)

Today while I was reading my chem textbook I was distracted by a sidebar note about a 1982 change in metal composition of the penny. I did some more research, and here's what I found:

Until 1982, pennies, were, for the most part, 95% copper and 5% zinc or zinc/tin alloy. In 1982, rising prices of copper caused the US Mint to change the composition of the cent coin to 97.5% zinc and 2.5% copper. Curious, I decided to calculate the actual value of the metal in each type of coin. I also used density values of each metal to determine the volume of each coin (which should remain roughly the same, otherwise we'd notice the coin being a different size).

Pre-1982 US 1-cent coin:

mass: 3.11 grams
composition: 95% copper, 5% zinc
volume: 0.354 cc
value of metal: $0.0246

1982-present US 1-cent coin:
mass: 2.50 grams
composition: 97.5% zinc, 2.5% copper
volume: 0.353 cc
value of metal: $0.00884

Canadian 1-cent coin:
mass: 2.35 grams
composition: 94% steel, 1.5% nickel, 4.5% copper
volume: 0.291 cc
value of metal: $0.00328

(These calculations are based on the data I was able to cull from the web: copper is worth $0.00814/g, zinc is $0.003542/g, nickel is $0.02893/g, and steel is$0.000631/g.)

So, the metal in a US penny issued before 1982 is actually worth about 2.5 cents. A penny hoarder with a smelter could turn a profit by melting pennies down and selling the metal as scrap!

There has been public debate about whether the US one-cent coin is obsolete and should be removed from circulation. As we see above, the metal in the coin itself is worth almost $0.01 already, which means that the cost of making the coin probably means a loss for the US Mint. Pennies are popular, however, which is one reason why they are kept in circulation.

Time Perception

J and I typically have trouble finding parking in North Beach: if it weren't for the fact that two of our best friends live there, I doubt I'd ever go. Tonight, J was doing the driving, and hence, the search for a parking spot. After about ten minutes of circling, looking at spots that were just barely too small for my Mini Cooper, and getting beaten to spots by other parking predators, I looked up at the clock and noticed that actually, only two minutes had passed. Not ten.

I remembered reading a long time ago that feverish people have distorted perceptions of time, and I wondered whether this phenomenon applied to people who were anxious too. It seemed logical to me that stimulation of bodily systems might mess up our ability to judge the passage of time.

One of the original studies about fever and time perception was conducted by a psychologist named Hudson Hoagland. In 1933, his wife had a fever and sent him to the drugstore for medicine. When he returned twenty minutes later, she complained that he had taken over an hour to run the errand. Inspired by her insistence, he asked her to count to sixty at what she guessed were one-second intervals, and, sure enough, her perception of a minute ranged from 34 seconds to 52 seconds. The higher her temperature, the more distorted her perception of time.

Apparently, the cause of this has to do with fever speeding up metabolism, heart rate, reactions of enzymes, and other bodily functions that impact our perception of time. Stimulation of the sympathetic nervous system (the "fight or flight" response) will also have this effect.

I found an article by Hancock and Weaver about time distortion under stress. They discuss a set of interviews conducted with pilots who ejected from aircraft during combat. Many of these survivors confirmed the sensation of a slowing of time when recalling their stressful incidents. Hancock and Weaver also cited a sadistic study in which arachnophobes were exposed to a spider for 45 seconds. Afterwards, they estimated the time of exposure to be (average) 60 seconds. People with no fear of spiders were used as controls in the same task, and they estimated the time interval more accurately (average = 41 seconds).

So, there you have it - predatory parking in San Francisco stimulates my fight-or-flight response, which probably increases my heart rate and blood pressure, and causes me to perceive that time is running faster than it really is. Maybe I will take up yoga, after all.

Scholarly reference (no link, sadly):

Hoagland, H., The physiological control of judgements of duration: evidence for a chemical clock. J. General Psychology, 9:267-287, 1933.

01 July 2006

Perfect Pitch

Musicians, especially singers and string players, are trained to recognize and correct pitch in order to play within the Western 12-tone scale (when playing Western music, obviously). There are different types of pitch-training skills.

Relative pitch is what most of musicians are working with: given a reference note (tuning fork, pitch pipe, other parts of a composition), we can identify pitches relative to that reference note. We can tell when we are singing flat or sharp even when the rest of the a cappella group is singing different notes than we are. We can hear when the piano is out of tune because of how the tones relate to each other.

Absolute pitch, also called "perfect" pitch, is the ability to identify a note by name without any reference pitch being given. Some research suggests that this ability is universally inborn, but disappears in childhood without musical training. Other sources demonstrate that absolute pitch tends to run in familes and among siblings. Studies state that the incidence of absolute pitch in adults is anywhere from 1 in 35 to 1 in 10,000.

What I learned today, which I found utterly fascinating, is that native speakers of certain languages (Vietnamese and Mandarin, among others) have a higher incidence of absolute pitch. It is believed that this is because tonal languages, in which changing the pitch of a spoken word changes its meaning, develops the same ear for perfect pitch as musical training. In one study, native tonal language speakers (without musical training, for the most part) were asked to read a list of Vietnamese or Mandarin words. The subjects of the study all spoke these words at virtually the same pitch. Another study (uncited, unfortunately - from an article in August 2006 Psychology Today) finds that absolute pitch is much more prevalent (32% vs. 7%) in conservatory students who are native speakers of tonal languages.

More details here.
And links associated with the University of California Genetics of Absolute Pitch Study.