Unitedâs iPhone App â How to Change Your Flight for Free. All airlines need to model their mobile app after Unitedâs iPhone App and offer to change your flight for free1. When you need a United Airlines flight change, there is no better way than to use Unitedâs Mobile App. It is one of the most useful travel tools I haveâ¦when I am flying on United that is.
English-born physicist John Wild (1914â2009) first used ultrasound to assess the thickness of bowel tissue as early as 1949; he has been described as the father of medical ultrasound. Subsequent advances in the field took place concurrently in several countries.
Ultrasound may also be used to assess blood flow to abdominal organs. Ultrasound uses a transducer that sends out ultrasound waves at a frequency too high to be heard. The ultrasound transducer is placed on the skin, and the ultrasound waves move through the body to the organs and structures within. The sound waves bounce off the organs like an echo and return to the transducer.