Purpose of the present research project is to study a new in-vivo test for abnormal platelet function and to study the effect of certain drugs on clinical bleeding. This is a randomized clinical trial of a new in-vivo test of platelet function known as the bleeding volume test(BVT)which relies on an on-line measurement system. This trial will assess the sensitivity and specificity of the new BVT by studying the effects of aspirin which is known to affect platelet function in-vivo. This is not a clinical trial of drugs. This is a clinical trial of a novel in-vivo on-line laboratory test.