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.
After surveying the parents of 350 children aged six months to 4 years old during October and November of last year, researchers learned that 75 percent of 4-year-olds have smartphones. About 97 percent of kids under age four have used a mobile device and 50 percent of children the same age had their own television. Nearly 100 percent of kids started using smartphones before their first birthday. Shockingly, nearly all (97 percent) children used mobile devices before their first birthday.