" In order to compute this quantity, physicists have to set up a lattice model and try out various masses for the quarks until the model comes up with a close fit with experimental data. Since the masses of the first generation quarks are significantly below the QCD scale, the uncertainties here are pretty large . In fact, current QCD lattice models seem to suggest a significantly lower mass of these quarks from that of this table. The fermions can be arranged in three generations, the first one consisting of the electron, the up and down quarks, and the electron neutrino. All ordinary matter is made from first generation particles; the higher generation particles decay quickly into the first generation ones and can only be generated for a short time in high-energy experiments. The reason for arranging them in generations is that the four fermions in each generation behave almost exactly like their counterparts in the other generations; the only difference is in their masses. For example, the electron and the muon both have half-integer spin and unit electric charge, but the muon is about 200 times more massive. Great Lake Ship Model The electron and the electron-neutrino, and their counterparts in the other generations, are called "leptons", "weakly interacting particles". Unlike the quarks, they do not possess a quality called "color", and their interactions are only weak and electromagnetic, and fall off with distance. "

", view produces a screen listing the shopping cart contents). The view gets its own data from the model (or direct from the data access layer - sometimes there is no domain logic to do). The model should have no direct knowledge of the view. However, the observer pattern can be used to provide some indirection between model and view, allowing the model to notify interested parties of a change. A view object can register itself with the model and listen for changes but the model itself remains view-agnostic. The controller does not pass domain objects (the model) to the view although it might issue a command telling the view to update itself. The user interface waits for further user interactions, which begins the cycle anew. Battle Ship Model Benefits and liabilities Although widely used, MVC has both advantages and disadvantages compared to other design options, and individual circumstances should be used to choose the most appropriate design. We discuss some of those here. "