I'm puzzled as to why the word, vector can mean a direction and magnitude in mathematics, but in biology, it refers to a particular pathogen. The two meanings seem incongruous. Were the biological definition something like, "The pathway taken by a pathogen in spreading infection," it would seem reasonable, but that's not how I've seen it described. Kalleh, since you're in medicine, how do you use it?
Well, Asa, the way I see it is that they are both pathways. In a biological vector, an organism, such as a mosquito or tick, carries disease-causing microorganisms from one host to another, thus providing a pathway for the disease--or a direction for the disease. In mathematics, then, a vector is a quantity, such as velocity, completely specified by a magnitude and a direction; so in a sense, it too provides a pathway. Similarly, in genetics a vector is an agent that transfers genetic material from one cell to another, thus again a pathway. I am much more familiar with biological vectors than mathematical or genetic ones, so I welcome other comments.
No, CJ, I don't suppose that counts. Do you market your knives like some companies do by cutting a can, or other piece of metal, in half? I have always wondered who would cut metal with kitchen knives anyway!
Asa, a colleague gave me the following explanation that may be better than mine: A vector carries a transmissible disease, and a mathematical vector carries a value, both in a particular direction. Is that better? Mathematical experts, does that work for your vectors? It does for biological/genetic vectors.
In math, according to AHD, a "vector" is a quality, such as speed, that is fully defined by its magnitude and its direction. That is, you can fully define a speed by stating "How fast, and which way?"
It's not clear to me, though, how this parallels the medical definition. The medical meaning seems closer to the etymology.
Do you market your knives like some companies do by cutting a can, or other piece of metal, in half? I have always wondered who would cut metal with kitchen knives anyway! *********************************** You mean, there's ANOTHER way to open a can? Damn! I've been single too long! Well actualy, I do have a pneumatic chisel at work, but that's overkill on a can of beans.
Asa, your last post is a pun waiting to happen, I am sure. Unfortunately, my brain doesn't work that way. Perhaps a dose of your pneumatic chisel would help!
Back to vectors: Shufitz, while direction would definitely fit the vector definition in biology, I agree that magnitude doesn't. Interesting.
