Guide Index Electronic Eyes Mind Over Machine A Heart of Titanium Building Hi-Tech Exoskeletons

SUPERHUMANS & BIONICS:
A Heart of Titanium

People whose hearts do not work properly have few options. There are not enough donor hearts for all the people who need them. At best, an artificial heart would be temporary. A radical alternative, originally considered an interim device to keep a person alive until a transplant could be found, may be the long-term answer for some heart patients. An experimental approach, as seen on Frontiers, supplements the left ventricle with a pump and leaves the heart intact. For Michael Dorsey, a heart made of titanium is the best hope he has of surviving.

Math Challenges

 BIOLOGY anatomy CHEMISTRY solutions HEALTH MATH PHYSICS fluids, velocity

While some heart-related problems cannot be prevented, many others can be. You can keep your heart healthy by exercising regularly, sticking to a low-fat diet and not smoking. The American Heart Association currently recommends a diet that is no more than 30% in fat. The typical American diet is closer to 37%, so many people are working to eat lighter. Even the White House chef is under orders to cut the fat in the Presidential cuisine. Easier said than done? Here are some math challenges that will show you how.

MATH CHALLENGES

You buy a multigrain fruit snack, only to be puzzled by the 5 grams of fat listed under product information. Is this as bad as a bag of potato chips?
The first challenge is to figure out what % of the calories is derived from fat. How do you do that? A gram of fat contains 9 calories of energy. To calculate the percentage of fat calories, use this formula:

% Fat calories = Number fat grams x 9 divided by calories in a food

To figure out the percentage of fat calories in your total diet, you would have to tally everything you eat within a given period. Try these:
1. 2 tablespoons of peanut butter: 180 calories, 16 grams of fat
% fat =

2. frozen yogurt bar: 230 calories, 12 grams fat
% fat =

3. 1 3/4 oz. bag of potato chips: 270 calories, 18 grams of fat
% fat =

4. fruit snack bar: 150 calories, 3 grams of fat
% fat =

Do some other calculations, using food products in your cupboard.

1. A box of taco shells weighs 5.25 ounces. How many grams is that?
(1 oz. = 28.3 grams)

2. Each box contains 14 shells. What is the mass of each shell?

3. Each shell has 3 grams of fat and 55 calories. What is the percentage of fat in each shell?

4. A 2-oz. packet of powdered hot chocolate (120 calories) contains 3 grams of fat. You are mixing it with a cup of whole milk (150 calories) that contains 8 grams of fat. You are going to cool off your cocoa with a scoop of vanilla ice cream measuring 4 ounces (349 calories). If one cup of ice cream contains 24 grams of fat, what is the total fat content of the beverage?

5. You and your friend go out to lunch. The person whose lunch derives the higher percentage from fat pays for the meal. Who pays? Which lunch has less fat?

Hamburger (fat in grams: 26; calories: 500)

Large fries (fat in grams: 22; calories: 400)

Low-fat chocolate shake (fat in grams: 1.7; calories: 320)

Chef salad (fat in grams: 9; calories: 265)

Ranch dressing (fat in grams: 20; calories: 220)

Bacon bits (fat in grams: 1; calories: 15)

Croutons (fat in grams: 2; calories: 50)

Orange juice (fat in grams: 0; calories: 80)

To the Instructor: These activities are intended to be exercises in math and not a recommendation for any particular diet. Americans consume large amounts of fat, and the National Institutes of Health and the American Heart Association recommend less fat in the diet.

1. 80%
2. 47%
3. 60%
4. 18%
5. 148.6
6. 10.6 g
7. 49%
8. 23g or 33%
9. you, 37%; your friend, 46%; your friend pays, but eats a healthier lunch.

Note that one other factor, the amount of saturated fat, has not been included in these computations. For the fittest heart, no more than 10% of the total fat consumed should be of the saturated variety. The hamburger lunch contains more saturated fat than the salad.

 Scientific American Frontiers Fall 1990 to Spring 2000 Sponsored by GTE Corporation, now a part of Verizon Communications Inc.