How does down syndrome occur and why does it only happen on chromosome 21, why would it be an issue of say chromosome 1

All phased array transducer systems direct ultrasound pulses in the same direction to create a 2-dimensional image.

 The overall gain improves the signal to noise ratio.

 Images that display many shades of gray are also called low contrast.

 How many bits are needed to represent 32 shades of gray?

Which component of the transducer reduces the amount of ringing, making it possible to produce an image?

 What determines the frequency of a sound beam from a pulsed transducer?

A rare genetic disease occurs in 1 of 200,000 people. You live in a city with a population of 800,000. What is the probability that 2 or less people with the disease live in your city?

A scintillator counts radioactive events in an experiment to track radioactively labeled DNA. For a given concentration of the labelled DNA, we expect to observe 3 events per second on average. What is the probability to observe 2 events in a given second?

You have an experiment that allows you to measure a value xx with a standard deviation of ±5.0\pm 5.0 caused by statistical noise. How many times do you need to repeat the experiment to be able to report x±1.0x \pm 1.0 with a 95% confidence interval?