* Positron Emission: Positron emission is a type of radioactive decay where a proton within the nucleus transforms into a neutron, releasing a positron (a positively charged anti-electron) and a neutrino.

* Nuclear Change: This process effectively reduces the number of protons by one and increases the number of neutrons by one.

* Ratio Shift: Since the number of protons decreases and the number of neutrons increases, the neutron to proton ratio (N/Z) becomes higher.

Example:

Consider a nucleus with 6 protons and 8 neutrons (N/Z = 8/6). When it undergoes positron emission, it becomes a nucleus with 5 protons and 9 neutrons (N/Z = 9/5). The neutron to proton ratio has increased.

In Summary:

Positron emission leads to a decrease in the neutron to proton ratio in a nucleus because it converts a proton into a neutron.