Science Fare

A "C" whistle

2008-08-23T12:16:00.004-05:00

The pitch of a whistle is determined by its length, and the speed of sound (340 m/s).

To determine how long to make a whistle, you need to know the frequency of the desired pitch:

Based on A 440 (A5), you can determine the frequency of C5 (three half steps higher than A5) by multiplying it by 2^(3/12). 3/12 is 0.25, and 2^0.25 is 1.189. 1.189 * 440 = 523. Higher octaves are multiples of 2: 1046, 2092, 4084. ( units: Hz, which is also 1/s)

The length of the whistle is simply the speed of sound divided by the frequency:

C5 : 0.65
C6 : 0.33
C7 : 0.16
C8 : 0.08

It's this last one that interests me -- because an oboe reed is approximately that length, and it sounds "C" when blown by itself.

But curiously, an oboe reed isn't 8 cm long -- they're usually 6.9-7.1 cm. What would account for this difference?

It turns out that the value for the speed of sound I used was for dry air at sea level at 60 degrees (F).

However, an oboe reed is blown, so the air moving through it is 98 degrees, and 100% humid. Calculating the correct speed of sound requires knowing the density of the air, and its adiabatic constant. Fortunately, someone has already calculated this. They give these values:

30°C 351.51
40°C 359.17

Linear interpolation for 37° gives us close approximation for the speed of sound through human breath: 357 m/s

Using this revised value, we find that our ideal oboe reed would be 8.5 cm. This is ever further from the actual length of an oboe reed!

So where does the additional 1.6 cm come from? If the pitch of the instrument was determined entirely by the length of the reed, then it would be impossible to influence the pitch of the instrument by how you play (e.g. your embouchure). I assure you, the pitch of the oboe is very easy to influence! Therefore it is clear that the musician is part of the instrument -- Thus the extra 1.6 cm are coming from the resonance of the players mouth.

Kudos for Lr2

2008-08-07T21:18:00.001-05:00

I upgraded to Lightroom 2 last week... so far, every single change that I’ve noticed has been for the better. It’s a remarkable improvement over what was already one of my favorite pieces of software ever.

From Daring Fireball

Adobe Photoshop Lightroom 2

2008-07-29T12:08:00.002-05:00

Download the free 30-day trial now! Existing users can upgrade at a discounted rate!

Eric put up a snap of the about box. Can you find my name?

Discharge for N F Flathead river

2008-07-26T18:54:00.003-05:00

You can see how well we're staying afloat next week by checking that live data report from the USGS:

http://waterdata.usgs.gov/nwis/uv?site_no=12355500

Dad is hoping for around 2000 CFS. Based on the data for the last 8 days, I think it should reach that just when we put in on the 31st. It depends on whether it rains in the next week, and how warm it is (which will influence how quickly the glaciers and snowpack melt). If it is a lot higher than 2000 CFS, it can make negotiating the log jams more treacherous. But also more exciting...

Speaking of melting glaciers, it looks like the mean water temperature is 15 degrees C. Which seems down right balmy for melted snow. But keep in mind the gage station is in Columbia Falls, and we're going to be upstream of there. Closer to the source, and therefore likely to be colder water. I think Mike is bringing a wetsuit for the guy in the kayak...

gotta get me one of these

2008-07-20T23:44:00.000-05:00

Cap'n Tight Pants Returns... sortof

2008-07-16T08:57:00.000-05:00

One Minute Documentary : Wool

2008-07-02T19:42:00.001-05:00

Recent panorama of the 35-W Bridge

2008-07-02T17:09:00.001-05:00

A "Zoomify" panorama is here.

Yay Acipenseriformes!

2008-07-01T12:04:00.003-05:00

(Image courtesy of the University of Minnesota.)

As a paddlefish fan, I take heart when I hear of exciting news about any of the Chondrostian fishes. According to KELO news, the Gavins Point Fish Hatchery in Yankton, SD, has successfully bred the endangered Pallid Sturgeon entirely in captivity. Previously, they would harvest gametes from wild adults for the hatchery program.

I did much of the research for my master's degree program at Gavins Point Hatchery. They have a nice facility for raising paddlefish, sturgeon, and also walleye.

One Minute Documentary : Thread

2008-07-01T10:19:00.001-05:00

Click To Play

I'm a bio-med expert

2008-06-30T22:04:00.002-05:00

And I know two times as much about RNA-binding proteins as I do about pyrimidines. DNA and RNA are composed of two classes of nucleic acids: pyrimidines and purines. But don't ask me about purines, I know nothing about those.

Funny, it doesn't mention Lua, Lightroom, web design...

Heron Island

2008-06-16T22:20:00.003-05:00

One Day At A Time and I went for a four-hour bike ride on Sunday. We headed north to view an island on the river which was reported to have a few great blue heron nests on it. Wowie Zowie! The island was nearly flooded out of existence by the high water -- but the trees were still standing. Which was all the herons cared about. We stopped and gawked for a good long time, capturing a few decent pictures. The coolest part was watching the parents feed the young. The youngsters looks nearly old enough to fly.

We then came back via the stone arch bridge, pausing to admire the rush of water over St Anthony Falls, and to have an ice cream at the Stone Arch Art Festival, which happened to be going on.

Bleeding Heart Anatomy

2008-06-07T19:25:00.003-05:00

I noticed a cool feature of the bleeding heart flower. As it matures, each blossom undergoes a two-stage opening of its interestingly shaped petals.

The young blossom, shown upper left, doesn't have any openings to either its pistil (the pollen-receiving structure) nor the anther (the pollen-producing structure).

Upper right shows a middle-aged blossom which has unfurled the first set of petals. This provides an opening that an insect could enter the flower to gain access to the pistils (containd inside the "heart" of the flower).

As the flower ages futher, another set of petals open, revealing the anthers (lower left). At lower right is another shot of the same blossom, taken from the side to illustrate the exposed anthers.

I theorize that this approach gives the bleeding heart plant an evolutionary reproductive advantage. By exposing each part of the flower in series, it encourages cross-plant pollination. An insect visiting a young blossom may carry pollen from another plant, but can't pick up pollen from the self-same blossom. This grants an advantage to the offspring, which will have a more genetic variation, and will therefore be more likely to weather future selective pressures. Should this plant be out of range of any other individuals, self pollination is still possible (either from one older blossom to a younger one) or via one older blossom to itself.

Given this morphology I'd further hypothesize that the blossom might have two sources of nectar (one in each compartment) to encourage pollinators to visit both the anthers and the pistils.

----

Update: I was feeling guilty, as I hadn't actually dissected a flower when I wrote the above text. I wasn't really sure where the pistil was. Well, I think that it is right next to the anthers (in the "drop"), not inside the "heart" of the flower as I'd speculated -- at least in a mature flower. So my hypothesis may be invalid, or only partially correct (if, for example, the pistil elongates as the flower matures. It is rather a puzzle... why would the flower partially open, but keep the anther and pistil under wraps? I may have to do more investigation.)

Fun Feynman Story

2008-05-28T23:20:00.002-05:00

if you have a few minutes, this is a great story about Richard Feynman -- one of my heros.

spring is sprung

2008-05-21T22:17:00.002-05:00

snapd outside before work

Thank You!

2008-05-17T15:37:00.003-05:00

Cooking some potato salad, listening to the latest Rahn Ramblings mix cd.... of which I"m the only recipient (because I haven't sent them out yet... oops).

Up comes Tami's song -- "so you had a bad day" is one of the lyrics.

I did not have a bad day. Had one of the best days of my life yesterday.

I had a good day at work.

Walked the dog.

And then... I played the Bach concerto for oboe and violin with Jim. I didn't think I could do it (but I never admitted that). Jim is also our music director, and he new I could do it. Thank you, Jim!

The orchestra sounded great! Thank you! Thank you everyone who said I did well!

My friends John and Jen and Jen's date Zachary came. Thank you!

Of course Becka was there! Thank you! Afterwards JZB & I went to Jasmine 26. It's a Thai restaurant that rocks -- might be as good as Chez Thuy. Of course we had Jasmine tea.

And then today we slept late (and sneezed a lot -- spring allergies are here), got fresh mango for breakfast, then walked the dog to the neighborhood Indian deli and got two fresh curries for lunch.

What a great start to a weekend!

(speaking of allergies -- they didn't bother me yesterday due to my theory that "you don't sneeze while being chased by a bear". Where "being chased by a bear" is anything that makes you excited. The stress hormones--cortizol, epinephrine and norepinephrine--suppress the immune system. Of course the next day, when the bear isn't chasing you any more... well, you start sneezing again. That's what sudephed is for!)

Natural Selection in Sticklebacks

2008-05-17T12:41:00.002-05:00

Catherine Peichel at the Fred Hutchinson cancer research center made an interesting discovery while studying the stickleback fish in Lake Washington. Over the last 40 years, the fish changed from a freshwater morphology, to a more marine one. This change is linked to a particular gene. She hypothesizes that pollution in the lake has selected for the marine allele, which causes the fish to have more bony armor and may help protect the fish from chemicals in the water.

Link: PDF and also a nice write up by the discovery channel.

I'm smarter than you -- I studied biology

2008-04-25T13:34:00.001-05:00

2008-04-14T20:01:00.002-05:00

Ok, I like this blog called Pharyngula. The guy is totally outspoken, but I often agree with him.

Just doin' my part by linking to a site about an awesome movie called Expelled Exposed. It is a counter film to the movie Expelled.

OK I suppose I should go watch what I'm linking too....

Upcoming Concert

2008-03-04T22:42:00.001-06:00

Friday, March 7, 2008, 7 p.m.
Grace University Lutheran Church
324 Harvard Street SE

James Riccardo, conductor and director
Romeo & Juliet Overture Peter Tschaikowsky
Katherine on my Chest/ with you at your Grave Stanley Woolner
Symphony #1 in C minor, Op 68 Johannes Brahms

Reduced Parking available for event at Fairview-University Patient/Visitor Parking Ramp at Harvard and Delaware Street,SE

Cavity Filled

2008-01-29T21:34:00.000-06:00

My Mom really wanted to see the filling -- so here it is!

Who gives a grammar?

2008-01-24T22:48:00.000-06:00

I noticed that my previous post used the word "Its" where I should have used "It's". Sigh. It is hard enough to keep up with all the one-off communications in life. Email messages. Instant messages. Who has time to craft grammatically correct sentences?

Well, I don't try to be intentionally horrible about it, but blogging is one of those "conversational" formats that lends itself well to breaking the rules. Sentence fragments. Misspeelings. poor capitalization. Embrace chaos.

Cavity

2008-01-23T21:26:00.000-06:00

I used my handy USB microscope to check out my new cavity. It gets a filling on Monday, so I should be able to do a nifty before&after comparison.

Its in that crevice. The dentist said it probably wasn't my fault, since a toothbrush bristle can't reach into that space.

Eskit's Giulianin Piece

2008-01-04T09:14:00.001-06:00

OMG. This is hilarious.

Look for the jammin' EH & bass in the musical interludes at 1/2 and 15/16ths.

Evolution book from National Academy

2008-01-03T22:25:00.000-06:00

Are you a creationist? You're not alone. But there is help: The National Academy of Sciences has updated its free booklet, "Science, Evolution, and Creationism". Check it out, please; the modern world of science misses you.

Others have argued that science teachers should teach the “controversies” surrounding evolution. But there is no controversy in the scientific community about whether evolution has occurred. On the contrary, the evidence supporting descent with modification, as Charles Darwin termed it, is both overwhelming and compelling. In the century and a half since Darwin, scientists have uncovered exquisite details about many of the mechanisms that underlie biological variation, inheritance, and natural selection, and they have shown how these mechanisms lead to biological change over time. Because of this immense body of evidence, scientists treat the occurrence of evolution as one of the most securely established of scientific facts. Biologists also are confident in their understanding of how evolution occurs.