Travis Edwards, The Follow Through Fixer: A selftaught inventor navigates the patent process on his own as a Pro Se applicant. Patent ductus arteriosus (PDA) is a condition in which the ductus arteriosus does not close.The word "patent" means open. The purpose of this guide is to provide you with basic information about filing a utility patent application with the USPTO. Pulse pressure is the difference between systolic and diastolic blood pressure. It is measured in millimeters of mercury (mmHg). This tutorial will focus on patents and the process for securing a patent in the U.S. First, let's consider why we have a patent system?