Officials said the Texas herd now being tested might have been mistakenly given feed meant for other animals.
But to prevent the spread of prion-associated maladies, Mr. Matheson said, cows would not be given feed made from cows, genetically engineered or not.
On Tuesday, the F.D.A. cleared for market 56,000 pigs given feed that included scraps of pet food contaminated with melamine.
Still, this is the first time federal officials have learned that cows in the United States were given feed made through unsafe practices.
Live animals are captured and fitted with collars that give their location every 15 minutes, and they are given feed containing a tiny transmitter that remains in the body and monitors heart rate and temperature.
Two modes of operation are considered: (I) given feed rate and (II) optimized throughput.
It is shown that, for given feed composition and column size, there is an optimum of the amount of fresh feed injected per cycle; alternately, for given feed composition and amount treated per cycle, there is an optimal column length.
Uniqueness of a limit point for given feed conditions guarantees its accessibility in the singular control operation.
Moreover multiple solutions are observed in the autocatalytic reaction for a given feed ratio, Damköhler (DaI) and Péclet (Pe) numbers.
Three modes of operation are considered: (I) given feed rate, (IIa) maximum throughput, and (IIb) "optimized" throughput.
Osmotic membrane separation processes are based on using semi-permeable membranes to remove solutes from a given feed solution.
