Due Wednesday, September 8
Read the syllabus and review the schedule.
What was the hypothetical example of a measurement, or set of measurements, that you
may need to make in your future discussed by your group in class?
Group number _NA__
Detection of the anthrax-causing bacteria Bacillus anthracis.
For that example, answer the following questions.
What is the purpose of the measurement?
What will be done with the information
that is obtained?
The purpose of the measurement is to determine, using a hand-held instrument and in real time,
if there is anthrax in a sample.
One possible scenario of what will be done with the information follows.
If it is determined that,
for example, the powder in a letter is anthrax, then the building will remain closed and
decontamination procedures initiated, health officials notified, testing and treatments begun, etc.
Additional samples will be tested by swabbing such places as the mail rooms that handled the
The samples will be retained as part of a legal chain of evidence for a court case.
sample(s) will go on to another lab for identification of the strain, to try to determine its origin,
and thus the perpetrator.
On the other hand, if the sample does not contain a health-affecting
level of anthrax, then the employees can return to work.
How accurate does your answer need to be?
We need to determine whether there is a concentration above background.
varies across the country, with anthrax being endemic in some states, including California.
those places, it exists in the environment at levels too low to cause significant harm to humans.
(According to http://www.textbookofbacteriology.net/Anthrax_3.html, there are only 1-2 cases
per year of naturally acquired anthrax.)
Using our rule of thumb of 2x signal to noise to be sure that we have a signal, we could say that
the accuracy must be 0.5 to 1x the noise (background) level, or a certain number of spores per
This number was not readily available online, but can be obtained through research.
One could alternatively consider using as the minimum level that must be detected some fraction