Saturday, April 05, 2003
Creature feature #1: bird breath
At lab meeting yesterday, I learned some cool facts about the avian respiratory system (among other things). It seems that birds have evolved a more efficient method than mammals to extract oxygen from the air and remove carbon dioxide from their bloodstream, perhaps due to increased demands for oxygen during flight and decreased availability of oxygen at higher altitudes. This increased efficiency of respiration results from the presence of air sacs both upstream and downsteam of the actual lung that create a unidirectional flow of air. In effect, all the parts of the bird lung are exposed to "fresh" air from the outside. By contrast, when we breathe, the air coming in mixes with the air going out, which decreases the overall level of oxygen. See this page for a nice description of the anatomy of the avain respiratory system. Also, see here for a cool shockwave plugin that demonstrates how the airsacs act as "bellows" to keep the air flowing in one direction.
The question was then asked whether our relatively inefficent respiratory system puts a damper on our physical activity. That is, if we could breathe like birds, would we be super athletes? The answer is a resounding "no". The average person uses only 60%- 85% of their ventilatory capacity, even while doing maximal exercise. A trained athlete uses around 90%, but ventilation capacity is almost never a cap on performance. Fitness training seems to improve the ability of the cardiovasculatory system to deliver oxygen to the tissues, but does not increase lung capacity. However, it was mentioned that a few elite athletes have become so fit that they have reached their pulmonary limit, but I can't find examples of these on the web. Since I am in no danger of even nearing my pulmonary limit, I guess I have no excuse not to go to the gym.
Bodies of evidence
News is emerging that British forces have found an Iraqi morgue on a military base on the outskirts of Al Zubayr (near Basra) that contains the remains of an unconfirmed number of people (hundreds?), many of whom had been shot in the head. The remains did not appear to be recent, and it is speculated that the bodies may be those of people who were executed by the Ba'ath regime. Given the sensationalism and then subsequent backtracking by the media lately, this is all to be taken with a grain of salt. If it is true, however, it will be a piece of evidence that somewhat eases my anxiety about the purported motivations for this war. Its one thing to hear an accusation, and another to see the evidence that supports it.
Personally, I'm still waiting to see pictures of the underground warehouse of chemical weapons and anthrax stocks being revealed to U.N. inspectors and skeptical Iraqi witnesses. At that point I will breath a very conflicted sigh of relief.
Thursday, April 03, 2003
So that's what they were doing....
While reading an article in TCS about the historical relationship between medical advances and war, I finally figured out what was going on in HBO's Band of Brothers when the medics would sprinkle powder into someone's wound. I assumed that the powder was some sort of antiseptic, and was skeptical about the effectiveness of putting this onto a severed leg, especially during the heat of battle. Turns out, it was probably crystals of zeolite, an absorbent mineral that mixes with blood to quickly promote clotting. Isn't that interesting? And yet, I hope I never need that information.
Wednesday, April 02, 2003
Why "positive and dense"?
This is a phrase from one of my favorite poems by Walt Whitman. I like this poem because it emphasizes an empirical, rather than a metaphysical, approach to understanding the world.
I AM THE POET
I am the poet of reality
I say the earth is not an echo
Nor man an apparition;
But that all the things seen are real.
The witness and the albic dawn of things equally real
I have split the earth and the hard coal and the rocks and the solid bed of the sea
And went down to reconnoitre there a long time,
And I bring back a report,
And I understand that those are positive and dense every one
And that what they seem to the child they are
[And that the world is not a joke
Nor any part of it a sham].
Sunday, March 30, 2003