Instantaneous portraits can now be taken on collodion by a very ingenious French invention. The person whose portrait is to be taken is placed at some distance off, in front of the lens ...

When a relationship between two variables is defined by a curve it means that the gradient, or rate of change is always varying. An average speed for a journey can be found from a distance-time ...

The following is a summary of "Accuracy of Instantaneous Wave-free Ratio and Fractional Flow Reserve Derived From Single ...

A streamline is a line that is tangential to the instantaneous velocity direction (velocity is a vector, and it has a magnitude and a direction). To visualize this in a flow, we could imagine the ...