Vector Fields in Maple. A vector field is described by a function that takes each point of the plane to a vector. > with(linalg): > F := (x,y) -> [-y,x]; We can evaluate this function at a point by plugging in values for x and y , just like we do with functions whose values are scalars.
The survey of U.S. parents finds that out of children participating in Fall and Winter sports, just 60 percent are wearing mouth guards. Taking a closer look at mouth guard usage for some higher-impact sports, the survey shows that for football, just 32 percent of parents report their child wears a mouth guard, for field hockey, just 14 percent. Lacrosse and ice hockey both fall at 11 percent, alongside volleyball. The complete list can be found here.
Now a new study from the Pew Internet & American Life Project found that 97 percent of kids played video games regularly. The survey group was composed of 1,102 young people between 12 and 17, and also polled their parents on topics. Boys do hold a slim lead in video game play percentage. While 94 percent of girls now play video games, 99 percent of boys do. Video games may be the great uniter, as race, ethnicity, income, and, for the most part, gender showed little variation. In fact, 7 percent of kids said they didn't even have a computer in their house, but they owned a game console.