Sperm's lifespan. It takes around 10 weeks for the sperm to reach maturity. Once the sperm is inside the woman's body it can live up to 5 days or even longer under favorable conditions. However, when it is outside the body, it can only survive from few minutes to several hours.
The UX developer role is a discipline under the overall user experience umbrella. This means that to become a UX developer you need to have at least a general understanding of the core UX principles, philosophies, and methodologies.
A fundamental reality of application development is that the user interface is the system to the users. What users want is for developers to build applications that meet their needs and that are easy to use.