1 / 13

PROBLEMS OF SIZE AND SCALE

PROBLEMS OF SIZE AND SCALE. Why Size is So Important. We know that a whale. requires more energy (food, calories) per day than a mouse. Metabolic Rate vs. Body Size Scaling. But how much more?. written by Jonathan Swift in 1726. Gulliver in Lilliput - Lilliputian King is faced

xena-gross
Download Presentation

PROBLEMS OF SIZE AND SCALE

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. PROBLEMS OF SIZE AND SCALE Why Size is So Important

  2. We know that a whale requires more energy (food, calories) per day than a mouse. Metabolic Rate vs. Body Size Scaling But how much more?

  3. written by Jonathan Swift in 1726 Gulliver in Lilliput - Lilliputian King is faced with a physiological problem - How much to feed Gulliver? King calculated 1728 Lilliputian portions.

  4. The story begins with early research on LSD using cats. If we’re not careful, we can run afoul of assumptions - to wit LSD and the Elephant It was discovered that a dose of 0.1 mg of LSD in a 2.6 kg cat caused aggressive behavior. It was subsequently decided that this might be a good model for studying musth in bull elephants.

  5. Musth is a condition of violent and uncontrollable rage. The elephant weighed 7722 kg. The “investigators” scaled up the dose by weight: (7722 kg /2.6 kg) = 2970 2970 X 0.1 mg = 297 mg (approximately 1500 X the human dose for a “trip”)

  6. Following injection, the elephant: • began trumpeting & running around • stopped • swayed • collapsed • convulsed • defecated, and • died The scientists concluded that elephants are particularly sensitive to LSD. Not so! Assumptions were incorrect!

  7. • • VO2 (or Em) = aMb • log VO2 = log(aMb) log VO2 = log(a) + b log(M) which has the form y = a + bx, where b is the slope of the line • There is an exponentialrelation between metabolic rate and mass: on a log-log plot this equation becomes a straight line:

  8. • Em (kcal • d-1) • log VO2 = log(a) + b log(M) 10000 1000 100 10 slope = b ~0.75 0.1 1.0 10 100 1000 Body Mass (kg)

  9. • VO2 / M (l O2 • h-1) / (kg) aM b VO2/M = = a M b-1 = aM -0.25 M • What about the weight-specific metabolic rate?

  10. mouse elephant • • Em (kcal • d-1) Em’ (kcal•kg-1•d-1) slope = -0.25 10000 1000 100 10 slope = 0.75 0.1 1.0 10 100 1000 Body Mass (kg)

More Related