Questions

The process which wherein an Ecosystem may renew itself is known as Ecological Succession.

The time scale may be decades or a million of years after a mass extinction. 

It may be achieve over a period of time.

The first identification of Nipah virus as a cause of an outbreak of encephalitis was reported in 2001 in Meherpur district of Bangladesh. Since, then Outbreaks of the deadly Nipah virus has been recorded almost every year in selected districts of Bangladesh.

Drinking raw date palm sap and contact with a case were identified as the major risk factors for acquiring the disease.

Veins are blood vessels that carry blood toward the heart. Most veins carry deoxygenated blood from the tissues back to the heart; exceptions are the pulmonary and umbilical veins, both of which carry oxygenated blood to the heart. In contrast to veins, arteries carry blood away from the heart.

Veins are less muscular than arteries and are often closer to the skin. There are valves in most veins to prevent backflow.