Neutrophils are the most common type of white blood cell, comprising about 50-70% of all white blood cells. They are phagocytic, meaning that they can ingest other cells, though they do not survive the act. Neutrophils are the first immune cells to arrive at a site of infection, through a process known as chemotaxis.
One of the basic theories stipulates that increasing interest rates raise consumers' and manufacturers' costs, which, in turn, reduces the amount of time and money people spend driving. Less people on the road translates to less demand for oil, which can cause oil prices to drop.
Prices for heating oil tend to be lower in the summer, as demand is a lot lower. So buying ahead will save you money. This also means you will avoid potential delivery problems in bad weather. However, be aware that because of the heating oil price drop in 2014, this year may be different and prices may rise again.