Three principal fields of research can yield useful data to understand these phenomena better: studies on explanted biomaterials, animal models and relevant in vitro techniques.
Thus far, systems engineering has been dealt with in relation to two principal fields of application.
The chapter shows the sound ranges and the principal fields of use of ultrasound.
Other principal fields in economics include economic history, health economics, cultural economics, economics of education, demographic economics, the study of nonprofit organizations, economic regulation, business management, comparative economic systems, environmental economics, urban and regional economics, and spatial economics.
This study proposes a method to generate filament-winding paths using the principal stress fields of the part to be manufactured.
The principal limitation of our study was the study design.
QHW was principal investigator of the study, participated in design of the study, field survey, and revised the manuscript.
Sandro Galea, chairman of the Columbia University Department of Epidemiology, was already steeped in this field when he became the principal investigator of the study.
WCR was Principal Investigator of the study, collaborated with others in designing the study, writing the protocol, supervising field work, interpretation of the data, and revising the manuscript.
All family physicians and internists in the study field had been invited to attend a lecture by the principal investigator of the study in the beginning, in which they were told about the study goals and protocol.
The participants were interviewed by the field workers before every participant met with the principal investigator of the study, who was a medical doctor, for consultation.
