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TWiM 14 Letters

Michael writes:
(in response to question on TWiM #9 - specimens for undergrad lab)

I am a student that is just starting the 2 year professional phase of my Medical Laboratory Science (MLS) degree. And from all I know, when possible, many of the samples that the program uses are actually from 2 major local hospitals. However this is not just any undergrad course, some of the lectures can be taken by students in the Molecular & Microbiology major, but the labs are restricted to only MLS majors.

By the way, I love TWiM! I started listening to TWiV in early 2010, I enjoy it even more that I can listen to you at 2x speed, and therefore I get 2x the info!

One suggestion for a future topic: it would be great for you all to discuss how the advances in technology will be able to change the time and types of medical testing. (such as PCR, flow cytometry, and maybe even microarrays, to name a few)

Thank you again!
~Michael

John writes:

Dear TWIMers,

I loved the pick of the week of the Life at Low Reynolds Numbers.  I originally read this a few years back, and it was recommended alongside a couple other papers that I thought would make good listener picks of the week.  Both papers are about scaling in biology, and why (for example) ants can't grow to be as big as a dog.

First, "On Being the Right Size" by Haldane:  http://irl.cs.ucla.edu/papers/right-size.html

Second, "The Biology of B Movie Monsters," by Michael LaBarbera: http://fathom.lib.uchicago.edu/2/21701757/

Thanks again for your wonderful podcasts!

--John

Rufus writes:

The aside regarding what it would be like to swim in corn syrup is actually a rather old question (Huygens).  Drag certainly goes up with viscosity, but viscous drag may not be the speed limiting factor for human swimmers  in water and propulsion efficiency may go up with viscosity over some range (say ethanol to water to pudding).

A chemical engineer decided to test it for humans in a liquid with double the viscosity of water using one of those small old four lane swimming pools:.  With double the viscosity, swimmers could maintain the same times!   http://blog.everydayscientist.com/?p=129.  http://it.umn.edu/news/inventing/2004_Winter/goingforthegoo.html.  Note in another secondary reference to the paper, though they could maintain the same speed,  athletes reported more fatigue from the viscous swims.

REFERENCE: "Will Humans Swim Faster or Slower in Syrup?" American Institute of Chemical Engineers Journal, Brian Gettelfinger and E. L. Cussler, vol. 50, no. 11, October 2004, pp. 2646-7.

I suppose our intuitions are even more suspect when looking at navigation and propulsion at the micro and nano scales.

Rufus
SW Engineer

Portland, OR

Dave writes:

I found the discussion of the two papers in TWiM #11 fascinating because you addressed the incredible complexity of biological systems and the immense difficulty of testing hypotheses of a simple cause and effect nature.  As a person with 50 years of experience in mathematical modeling and statistics, I have a great appreciation of just how difficult it must be to design valid experiments and models to test almost any biological hypothesis.

However, your discussion of entropy in response to a letter from one of your listeners seemed to wander off in strange directions.  I think the problem started with the letter writer misstating a key component of the second (not third as stated in the letter) law of thermodynamics.  Entropy or disorder increases "in a closed system", not in "any system" as the letter writer stated.  The biological examples he named that appear to counter this law were open systems.  These biological entities are obviously exchanging energy and matter with the greater universe.  This is what drives self-assembly and other apparent violations of the second law of thermodynamics.  I'm sure that any closed biological system that one could create would obviously "run downhill" from an entropy standpoint.

Thanks to you and your other panel members for the great podcasts.  Listening to TWiM, TWiV and TWiP is a highpoint of my week.

Dave
 

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