This type of subsistence farming is also called shifting cultivation. The traditional tribes of the Amazon rainforest use system of shifting cultivation. They chop down a clearing in the trees and use it for a few years before moving on and allowing the soil and vegetation to recover.ubsistence farmers only produce enough to feed themselves and their family, without having any more to sell for profit.This is the most common form of farming in LEDC's. Some of them are nomadic, meaning that they move around the country using a piece of land for a while and then moving on.
As a result, not enough blood flows through the valve. Some valves can have both stenosis and backflow problems. Atresia occurs if a heart valve lacks an opening for blood to pass through. Some people are born with heart valve disease, while others acquire it later in life.
Slow blood flow can occur if there is a narrowing of the blood vessel. This can obstruct the flow. One common cause is atherosclerosis. There are deposition of cholesterol or lipids in the wall of the arteries which can narrow it. Other causes can be an inflammation. In the veins there can be slow flow where there is difficulty in pumping blood from legs towards the heart. If you feel any symptom, you should get an examination you need to get it checked by doctor. Any query, please feel free to ask.