Integrated Alerting: It is possible to create Alert Rule with negative duration time

User Impact:
Users can create Alert Rule with a negative duration value.

Steps to reproduce:
Navigate to IA>>>Alert Rules and press Add to create Alert Rule
Add params to create Alert Rule
Specify negative Duration for the rule
Press Add

Actual result:
The rule is created with a negative value for Duration.
Expected result:
The rule can not be created with a negative value for Duration.