Dear Ms. Scientist,
Why do bridges ice before sidewalks?
—Rachel T.
Be aware as you cross the bridge between Humanities and Bascom Hill to your second-semester classes. Ice forms on bridges before sidewalks because of two reasons. One is that bridges have cold air flowing both over and under the walkway, unlike sidewalks that have an insulating ground beneath them. The second reason is bridges are made of materials that are good heat conductors, like steel. Any heat bridges contain easily moves to the surface and is swept away by the cold wind. Another factor may be that the bridge is crossing over something that is considerably colder than the ground, such as a river.
Dear Ms. Scientist,
Why is it some vaccines you only need to take once with only the occasional booster shot while you need to get the flu vaccine every year? I thought vaccines were supposed to give you long-lasting immunity?
—Ross G.
You’re right. The flu virus, whether received through a vaccine or an unfortunate infection, will give you long-lasting immunity—but only for that specific strain of the virus. Over the season the virus mutates leading to minute changes in its appearance and the production of new strains. The changes are just enough to escape your immune system’s first lines of defense, including antibodies. This process, called antigenic drift, occurs faster for the flu than many other viruses. The annual flu vaccine is also comprised of the strains predicted to be the most prevalent that season. New strains or other strains may predominate from year to year, demanding for new vaccines to be developed.
Ask Ms. Scientist is written by Corinne Thornton. If you have a burning science question you want her to answer, tweet @DC_Science or email it to science@dailycardinal.com.
