Math Insight

Quiz 7

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Total points: 8
  1. A species of birds is living on two nearby islands. If the islands were isolated, the population on the first island would shrink by 10% each year and the population on the second island would grow by 6% each year. However, each year, after the populations grow (or shrink), 9% of the population on the first island migrates to the second island and 9% of the population on the second island migrates to the first island.

    Is the total population of birds on the islands growing or shrinking?
    . Each year, the total population is multiplied by what factor?

  2. Bird flu (Avian influenza) is affecting chicken farms in Minnesota and you've been called in to help model the outbreak.

    Suppose you decide to use a metapopulation to model the fraction of chicken farms that currently have a bird flu infection as $\frac{dp}{dt} = C - E$ where $p$ is the proportion of farms that are infected, $C$ is the rate at which new infections occur and $E$ is the rate as which farms are able to eradicate influenza. Time $t$ is measured in months.

    From some preliminary assessments it appears that new infections occur when chickens are being imported from outside Minnesota (rather than new infections arising from chickens being transported from an infected Minnesota farm to an uninfected farm). Infected chickens are imported from outside farms at a rate of $0.1$ per month.

    What form should the infection rate $C$ take?
    $C=$

    Your plan to control bird flu is to eradicate the disease from infected farms at a monthly rate $x$, meaning $x$ is the fraction of infected farms from which the flu is eradicated per month. What form should the extinction rate $E$ take?
    $E =$

    Find all the equilibria:
    $p = $
    (If multiple answers, separate by commas.)

    Is it possible to completely eradicate the disease from Minnesota chicken farms?

    If so, how fast must you be eradicating the disease from individual infected farms to be able to completely eradicate the disease from Minnesota? (Your expression should be an inequality involving $x$.) If it is not possible, enter 'impossible'.